CN109179357B

CN109179357B - Method and system configuration for recycling compound fertilizer from polishing and cleaning wastewater in aluminum industry

Info

Publication number: CN109179357B
Application number: CN201810843393.0A
Authority: CN
Inventors: 熊映明
Original assignee: FOSHAN SANSHUI XIONGYING INNOVATIVE CENTER FOR ALUMINUM SURFACE TECHNOLOGIES Co Ltd
Current assignee: Huzhou Chuangguan Technology Co ltd
Priority date: 2018-07-27
Filing date: 2018-07-27
Publication date: 2020-03-24
Anticipated expiration: 2038-07-27
Also published as: CN109179357A

Abstract

The invention discloses a method and system configuration for recycling compound fertilizer from polishing and cleaning wastewater in the aluminum industry. The storage tank for storing spray wastewater, the high-pressure atomization spray tank is connected with the second non-flow washing tank through the storage tank; the aluminum phosphate recovery system includes a reaction tank, a No. 5 pump, a liquid ammonia tank and a filter press, and the reaction tank is connected to the The No. 1 pump is connected, and the N‑P compound fertilizer recovery system includes a recovery tank, No. 7 pump and a filter that are connected in sequence. The invention also discloses a method for recycling compound fertilizer from polishing liquid. The polishing liquid is retained in a washing tank for centralized treatment, which avoids the trouble of mixing with other water and then treats these massive wastewaters, greatly reduces the environmental protection cost of treating phosphorus-containing and ammonia-nitrogen wastewater, and greatly reduces the discharge of nickel-containing solid hazardous waste. Adopt high-pressure atomization spray tank to reduce the amount of waste liquid recovery.

Description

Method and system configuration for recovering compound fertilizer from polishing and cleaning wastewater in aluminum industry

Technical Field

The invention relates to the technical field of aluminum product processing, in particular to a method and system configuration for recovering compound fertilizer from polishing and cleaning wastewater in aluminum industry.

Background

The aluminum alloy has the advantages of excellent processing performance, good corrosion resistance, beautiful surface, high recovery rate and the like, and is widely applied to the industries of buildings, transportation, machinery, electric power and the like. In recent years, the trend of replacing copper, wood and steel with aluminum and expanding the application range of aluminum is more obvious. The aluminum processing industry is not only a traditional industry, but also a sunrise industry full of bobby vitality. According to statistics, people in developed countries in Europe and America consume more than 32kg of aluminum alloy every year, while people in China only have about 13kg and only one third of developed countries, and the consumption of the aluminum alloy in China has huge growth space. However, the common problems of high energy consumption, large total pollution discharge amount and low resource recycling rate in the aluminum processing industry are obvious bottlenecks and obstacles restricting the industry development.

The production in the aluminum industry comprises the working procedures of electrolysis, casting, pressure processing, surface treatment and the like, and waste gas, waste water and waste residue with different degrees are generated in each working procedure during production. A large amount of aluminum ash is generated during electrolysis and casting, a die-cooking alkaline waste liquid is generated in the extrusion process, and various waste water and waste residues containing acid, alkali, treatment agents, chromium, nickel heavy metal ions and other complex components are generated in the surface treatment process.

The method adopts a mode of treating wastes with wastes, the waste liquid of the die-cooking, the waste water of the oxidation wire, the waste water of the spraying wire and the waste water of the polishing wire are all discharged to the center of the waste water for neutralization, the waste water collected at the center of the waste water contains cations such as Al3+, Na +, NH4+, Ni2+, Sn2+, Cr6+ and the like, anions such as SO42-, F-, NO3-, NO2-, S2-, Cl-, tartrate, gluconate, acetate and the like, and organic matters such as organic phenol, surfactant, acrylic resin and the like. The acidic waste water and the alkaline waste water are usually treated by mixing and neutralization, while the chromium-containing waste water and the nickel-containing waste water must be treated separately. In recent years, the proportion of the oxidation electrophoresis material is reduced, but most aluminum material factories still have more acidic wastewater than alkaline wastewater, acid and alkali water are all mixed together for treatment, the wastewater is acidic after being mixed, a large amount of caustic soda flakes, lime, PAC and PAM are required to be added, and a large amount of waste residues are generated. A large amount of useful resources such as metallic aluminum, acid, alkali and the like in the waste residue are not utilized, and huge resource waste is caused. The waste residue belongs to hazardous waste, contains various toxic and harmful substances such as aluminum hydroxide, fluoride, sulfide, nickel salt, phenol, nitrate, nitrite and the like, has great environmental hazard, can not be buried, and has great environmental hazard. After central treatment and solid-liquid separation of the wastewater, the reclaimed water contains sodium ions, ammonium ions, sulfate radicals, nitrate radicals, nitrite radicals, acetate radicals, tartrate radicals, thiosulfate radicals, chloride ions, sulfide ions, fluoride ions and the like, and can not be recycled. The current environment-friendly situation forces enterprises to change and develop towards the direction of energy conservation, emission reduction and resource recycling, but the enterprises are lack of mature and reliable technologies. Realizes the complete reuse of reclaimed water, zero output of waste residue and maximized resource utilization value, and has great environmental benefit, social benefit and economic benefit.

The latest version of the national records of dangerous wastes, which was applied from 8.1.2016, has recorded the records of acidic and alkaline waste water and waste residues in the records of HW34 and HW 35. Acid slag, alkaline slag, chromium slag and nickel slag are listed in the latest edition of national records of dangerous waste.

Aluminum alloy polishing is an important means for producing high-grade aluminum materials, and polishing aluminum materials are generally selected for shells of various electronic products, interior decoration of high-speed rails, bathroom equipment and the like. In addition to atmospheric pollution, the greater pollution of polishing is the pollution of triacid water. When one ton of polishing material is produced, 350Kg of triacid is consumed and then discharged into the center of wastewater along with the following cleaning tank. The extensive production mode has great harm, namely, triacid is lost, metal aluminum is wasted, and the consumption of the triacid reaches more than 300 kg/t; secondly, the waste acid treatment increases considerable cost; thirdly, a great amount of waste residue causes environmental harm.

The use of a non-flowing rinsing bath to retain polishing solution after polishing and to evaporate for reuse has been a widely used acid-saving means. However, the trapped triacid generates a large amount of smoke in the evaporation process, so that the environment is polluted and the treatment cost is huge; the energy consumption in the process of evaporating the triacid is huge, and the cost cannot be viewed; the evaporation container is corroded too fast and needs to be replaced every two years, and the investment is too much. In the practical operation of recovering the triacid, the defects of large pollution, high energy consumption, low efficiency, high cost and the like exist. In view of the poor use of triacid recovery, most aluminum processing enterprises have gradually discontinued triacid recovery, restoring the traditional method of direct discharge into wastewater centers.

The reduction and resource direction of the aluminum ash and the aluminum slag in the aluminum industry is as follows:

1. the principle followed is: the reduction control, the harmless treatment and the resource utilization can be actively developed only by combining three forces of government promotion, enterprise dominance and third party market allocation resources;

2. source control, namely classification interception, on-line conversion and resource utilization of each medicament tank, and reduction of the discharge amount of waste water and waste residue;

3. the surface treatment agent formula is improved, and the traditional Na-containing chemical component is replaced by a non-toxic, low-toxicity, easily-recycled and easily-cleaned chemical component⁺、NH₄ ⁺、Ni²⁺、Sn²⁺、Cr⁶⁺、NO₂ ^-、NO₃ ^-、Cl^-、F^-、CH₃COO^-The compounds such as gluconate, tartrate, S2O 32-and the like are taken from the source, so that the technical threshold of waste water recycling, solid waste harmless treatment and resource utilization is reduced;

4. and the production and research combination is strengthened, the thought and the field of comprehensive utilization of waste residues are expanded, and the maximum comprehensive utilization value is realized.

The aluminum alloy polishing waste acid liquor is very large in quantity in some regions, such as a Foshan region, approximately 20 million tons of polishing acid are consumed annually, 6 million tons of sulfuric acid, 13 million tons of phosphoric acid and 1 million tons of nitric acid account for half of the national dosage of 40 million tons. The waste polishing acid is treated to generate over 100 million tons of phosphorus-containing waste residues every year in China, and simultaneously, about 5000 million tons of water is consumed.

A conventional polishing line for waste water and acid is shown in figure 1. The No. 1, No. 5, No. 8, No. 11 and No. 14 tanks are working tanks, each working tank is provided with a set of flowing water washing tank, 16 tank positions are needed for polishing treatment, wherein the No. 1 tank is a polishing tank, the No. 2, No. 3 and No. 4 tanks are washed by water subsequently to clean polishing liquid containing sulfuric acid, phosphoric acid and nitric acid, and wastewater enters a wastewater treatment center and is mixed with nickel-containing wastewater of a coloring and hole sealing tank to generate waste residue containing Ni-P-Al. At present, waste water and waste acid are treated by lime to generate calcium sulfate and calcium phosphate. The treatment mode has high cost, large waste residue amount and ammonia nitrogen discharge.

Modern aluminum processing enterprises have polishing waste liquid which is in urgent need of treatment, while the traditional method for treating the mixed cleaning water is too simple, so that a large amount of waste residues containing phosphorus and nickel are generated, the waste residues are treated, the society pays expensive environmental protection cost, and a new technology is urgently developed to solve the environmental protection problem of the polishing waste acid.

Disclosure of Invention

The invention aims to provide a compound fertilizer recycling system configuration for polishing and cleaning wastewater in the aluminum industry, which has the characteristic that polishing wastewater can be treated independently.

The invention aims to provide a method for preparing and recovering a compound fertilizer by adopting a compound fertilizer recovery system from polishing and cleaning wastewater in the aluminum industry, which has the characteristic of saving cost.

In order to achieve the purpose, the invention adopts the following technical scheme:

the preparation of a compound fertilizer recovery system for polishing and cleaning wastewater in the aluminum industry comprises a polishing tank, a first no-flow rinsing tank, a second no-flow rinsing tank, a high-pressure atomization spraying tank, an aluminum phosphate recovery system and an N-P compound fertilizer recovery system which are sequentially arranged;

the high-pressure atomization spraying groove, the second no-flow rinsing groove and the first no-flow rinsing groove are communicated in sequence and used for intercepting polishing liquid from the polishing groove; the high-pressure atomization spraying groove is connected with a storage tank for storing spraying wastewater, and is communicated with the second non-flowing rinsing groove through the storage tank;

the aluminum phosphate recovery system comprises a reaction tank, a fifth pump, a liquid ammonia tank and a filter press, wherein the reaction tank is communicated with the first pump, the fifth pump is arranged at the outlet of the lower part of the reaction tank, the liquid ammonia tank is communicated with the lower part of the reaction tank through a pipeline, the filter press is communicated with the outlet of the fifth pump through a pipeline, the outlet of the fifth pump is communicated with the upper part of the reaction tank through a circulating pipeline, and the fifth pump is used for circulating the liquid in the reaction tank through the circulating pipeline and pumping materials in the reaction tank to the filter press;

the N-P compound fertilizer recovery system comprises a recovery tank, a seventh pump and a filter which are sequentially communicated, wherein the seventh pump is used for pumping materials in the recovery tank into the filter, a liquid outlet of the filter press is communicated with the recovery tank, the bottom of the recovery tank is provided with the sixth pump, and an outlet of the sixth pump is communicated with a circulating pipeline.

Further, still include cooling system, cooling system includes cooling tower, No. four pumps and cooling circulation pipeline, and cooling tower and No. four pumps are all established on cooling circulation pipeline, and cooling circulation pipeline's cooling zone is located the retort, and No. four pumps are used for making the coolant liquid circulation in the cooling circulation pipeline.

The polishing solution is intercepted by the rinsing bath for centralized treatment, so that the trouble of treating massive wastewater after mixing with other water is avoided, the environmental protection cost for treating wastewater containing phosphorus and ammonia nitrogen is greatly reduced, and the hazardous waste discharge of nickel-containing solid is greatly reduced. And a high-pressure atomization spraying groove is adopted, so that the waste liquid recovery amount is reduced.

Further, a second one-way valve is arranged at the communication position of the first no-flow rinsing bath and the second no-flow rinsing bath. The storage tank is communicated with the second stagnant water washing tank through a pipeline, and a second pump is arranged on the pipeline and is used for pumping the spraying waste liquid in the storage tank into the second stagnant water washing tank; the first no-flow rinsing bath is connected with a No. one pump through a pipeline, and the No. one pump is used for pumping out bath liquid in the first no-flow rinsing bath.

After the water level in the first no-flow rinsing bath is reduced, the bath solution in the second no-flow rinsing bath can enter the first no-flow rinsing bath through the second one-way valve, and the second one-way valve can prevent the high-concentration bath solution in the first no-flow rinsing bath from entering the second no-flow rinsing bath. When the concentration of the bath solution in the first non-flowing rinsing bath is higher, the first pump pumps the bath solution out, and the waste liquid is collected for centralized treatment.

The cooling pipeline is used for cooling the bath liquid in the first stagnant water washing tank and the second stagnant water washing tank. The arrangement of the cooling pipeline can ensure that the bath solution of the two non-flowing washing baths is at a lower temperature level, and the brightness loss of the polishing material is reduced.

Furthermore, the high-pressure atomization spray tank is connected with a third pump, the cooling pipeline is communicated with the inlet of the third pump after passing through the second non-flowing water washing tank, and the third pump is used for pumping water in the cooling pipeline into the high-pressure atomization spray tank to be used as spray water. The cooling pipeline supplies water for the high-pressure atomization spraying groove, so that the cooling capacity of the two non-flowing washing grooves is improved to the maximum extent, and the pipeline structure of the system is simplified.

The method for preparing and recovering the compound fertilizer by adopting the compound fertilizer recovery system from polishing and cleaning wastewater in the aluminum industry comprises the following steps:

intercepting polishing wastewater: the aluminum alloy sequentially passes through a polishing tank, a first no-flow rinsing tank, a second no-flow rinsing tank and a high-pressure atomization spraying tank, polishing liquid carried by the aluminum alloy is intercepted by the first no-flow rinsing tank, the second no-flow rinsing tank and the high-pressure atomization spraying tank, and when the water level in the second no-flow rinsing tank is lowered, the polishing liquid is replenished by spraying wastewater in a storage tank;

collecting polishing wastewater: detecting the density of the bath solution in the first non-flowing water washing bath until the density reaches 1.25-1.31g/cm³Collecting the bath solution of the first non-flowing rinsing bath and feeding the bath solution into a reaction tank to obtain polishing wastewater, wherein the polishing wastewater comprises phosphate ions, nitrate ions and sulfate ions;

recovering aluminum phosphate and liquid N-P compound fertilizer: and starting a fifth pump to circulate a liquid tank in the reaction tank, adding liquid ammonia into the wastewater by the liquid ammonia tank until the pH value is 6.5-7.5, stirring for reaction, cooling, pumping a solid-liquid mixture in the reaction tank into a filter press by the fifth pump to separate solid from liquid, wherein the solid is aluminum phosphate and nickel phosphate, and the liquid enters a recovery tank from an outlet of the filter press to recover the liquid which is the liquid N-P compound fertilizer.

The system further comprises a cooling pipeline, the cooling pipeline sequentially passes through the first stagnant water washing tank and the second stagnant water washing tank, and the cooling pipeline is used for cooling tank liquor in the first stagnant water washing tank and the second stagnant water washing tank;

the production temperature of the first no-flow rinsing bath is controlled to be less than or equal to 50 ℃.

The liquid ammonia is added into the polishing waste liquid to obtain the aluminum phosphate and liquid N-P compound fertilizer, so that waste is changed into valuable, the waste liquid treatment cost is low, and the problems of high treatment cost of waste residues containing phosphorus and nickel in the polishing waste liquid and high environmental protection cost in the prior art are solved.

Further, the method also comprises the following steps:

and concentrating and crystallizing the recovered liquid N-P compound fertilizer, and drying and grinding the crystals to obtain the N-P compound fertilizer containing ammonium sulfate-ammonium phosphate-ammonium nitrate.

Further, the method also comprises the step of preparing the granular organic-inorganic compound fertilizer:

adding organic waste residue and waste residue containing zymophyte into the recovered liquid N-P compound fertilizer, fermenting and curing to prepare granular organic-inorganic compound fertilizer, wherein the water content of the organic waste residue is less than or equal to 10%.

Considering that the liquid N-P compound fertilizer has higher concentration and crystallization cost, the organic waste residue is utilized to absorb water and is added with the waste residue containing zymophyte to produce the granular organic-inorganic compound fertilizer, thereby saving the energy consumption and the environmental protection cost of concentration and crystallization, opening up the application of the organic waste residue, solving the problems of caking of the compound fertilizer and soil hardening, and achieving multiple purposes.

Further, in the step of preparing the granular organic-inorganic compound fertilizer, firstly adding waste residues containing zymophyte into the liquid N-P compound fertilizer, then gradually adding the organic waste residues, mixing the mixture uniformly, and performing ventilation fermentation until the mixture turns black to obtain a curing end point, thus obtaining the granular organic-inorganic compound fertilizer;

the organic waste residue is added until the mixture does not drip water.

The process difficulty can be reduced by setting the addition amount of the organic waste residue and the curing end point.

The invention has the beneficial effects that:

1. the polishing solution wastewater interception is set for the first time, and the two no-flow rinsing tanks and the high-pressure atomization spraying tank are responsible for interception and are reserved in the two no-flow rinsing tanks and the storage tank for later use. When the polished aluminum material is produced, the polishing solution is retained by the rinsing bath and is treated separately in a centralized manner, so that the trouble of treating massive wastewater after mixing with other water is avoided, the environmental protection cost for treating wastewater containing phosphorus and ammonia nitrogen is greatly reduced, and the discharge of dangerous waste containing nickel solid is greatly reduced;

2. the high-pressure atomization spraying groove is adopted in the polishing solution wastewater interception for the first time, so that the recovery amount of the waste liquid is reduced. According to the figure 1, when the polished aluminum material is produced in the traditional mode, 2#, 3# and 4# flowing rinsing tanks are arranged behind a 1# polishing tank, tap water enters from the 4# tank and exits from the 2# tank and is reversely connected in series, and more than 3 tons of water are consumed per ton of material; the polishing waste liquid is directly discharged into a waste water center and is mixed with the nickel-containing waste water to form solid hazardous waste. The method provided by the invention has the advantages that the residual polishing solution is recycled by a spraying method for the first time, so that the water consumption is greatly reduced, the waste liquid recycling amount is reduced, the recycling pressure is reduced, and a solid foundation is laid for online independent treatment of polishing wastewater and equipment miniaturization;

3. an aluminum phosphate recovery system is arranged on line for the first time and is responsible for recovering aluminum in the polishing solution wastewater, and aluminum phosphate and nickel phosphate are generated through reaction to realize solid-liquid separation;

4. an N-P compound fertilizer recovery system is arranged for the first time and is responsible for pumping the supernatant in the recovery tank into a filter for treatment and subpackaging a compound fertilizer solution; pumping the precipitate at the bottom of the recovery tank into the reaction tank again for secondary recovery;

5. the liquid ammonia is added into the polishing waste liquid to obtain the aluminum phosphate and liquid N-P compound fertilizer, so that waste is changed into valuable, the waste liquid treatment cost is low, and the problems of high treatment cost and high environmental protection cost of waste residues containing phosphorus and nickel in the polishing waste liquid in the prior art are solved;

6. organic waste residues (organic waste residues from plant sources and/or organic waste residues generated by processing agricultural and sideline products) (the water content is less than or equal to 10%) are used for absorbing water in the liquid N-P compound fertilizer for the first time, and the organic-inorganic compound fertilizer is prepared by solid-liquid mixing. The liquid N-P compound fertilizer recovered according to the invention contains more than 50% of water, and the concentration and crystallization not only consumes energy, but also is not environment-friendly and increases the cost. The organic-inorganic compound fertilizer is produced by properly adding dried and fresh vinasse into the organic waste residues and introducing yeast, and mixing the liquid N-P compound fertilizer recovered by the method, so that the energy consumption and the environmental protection cost of concentration and crystallization are saved, the application of the organic waste residues is expanded, the problems of compound fertilizer caking and soil hardening are solved, and multiple purposes are achieved.

Drawings

FIG. 1 is a schematic view of a prior art aluminum polishing line;

FIG. 2 is a schematic diagram of a compound fertilizer recovery method and system configuration and downstream production line for aluminum industry polishing and cleaning wastewater according to an embodiment of the present invention;

FIG. 3 is a schematic diagram of a compound fertilizer recovery system for aluminum industry polishing and cleaning wastewater in accordance with the present invention;

the device comprises a polishing tank 1, a first no-flow rinsing tank 2, a second no-flow rinsing tank 3, a high-pressure atomization spraying tank 4, a storage tank 5, a second pump 6, a first pump 7, a cooling pipeline 8, a third pump 9, an ash removal tank 10, a first flow rinsing tank 11, a second flow rinsing tank 12, an oxidation tank 13, a third flow rinsing tank 14, a fourth flow rinsing tank 15, a coloring tank 16, a fifth flow rinsing tank 17, a sixth flow rinsing tank 18, a hole sealing tank 19, a seventh flow rinsing tank 20 and an eighth flow rinsing tank 21;

the first check valve 01, the second check valve 02, the third check valve 03, the fourth check valve 04, the fifth check valve 05, the sixth check valve 06, the seventh check valve 07, the eighth check valve 08, the ninth check valve 09, the tenth check valve 010, the eleventh check valve 011, the twelfth check valve 012, the thirteenth check valve 013, the fourteenth check valve 014, the fifteenth check valve 015, the sixteenth check valve 016 and the seventeenth check valve 017;

the system comprises an aluminum phosphate recovery system 100, an N-P compound fertilizer recovery system 200, a reaction tank 101, a fifth pump 102, a liquid ammonia tank 103, a filter press 104, a circulating pipeline 105, a recovery tank 201, a seventh pump 202, a filter 203, a sixth pump 204, a cooling system 300, a cooling tower 301, a fourth pump 302 and a cooling circulating pipeline 303.

Detailed Description

The technical solution of the present invention is further described below with reference to the accompanying drawings and the detailed description.

The aluminum alloy polishing is intended to improve the decorativeness of the aluminum alloy. Typically two acids, three acids and electropolishing are employed. The triacid polishing solution typically contains sulfuric acid, phosphoric acid, and nitric acid. Taking three-acid polishing as an example, the tank liquid control indexes of the polishing tank are as follows (the tank liquid is prepared according to 100 parts by weight):

sulfuric acid 30 wt.%;

phosphoric acid 65 wt.%;

5 wt.% nitric acid; (1)

the temperature is 100 ℃ and 110 ℃;

the time is 20s-120 s;

the dripping time is less than 20 s;

aside from the fumes, the greatest confusion in polishing is the drip time. No matter electrolytic polishing, two-acid polishing or three-acid polishing is carried out, the dripping time cannot be too long, generally does not exceed 20s, the aluminum material is easily burnt out due to too long time, spots or tear marks are formed, and the polished material is unqualified.

As shown in fig. 1, in the prior art, three rinsing baths are provided to clean the residual polishing solution from the polishing bath and protect the ash removal bath. Tap water enters from the No. 4 tank, is discharged from the No. 3 and No. 2 tanks and is reversely connected in series, the water consumption is about 2.0 to 3.0 tons per ton of material, the water consumption is too large, and the discharged wastewater contains sulfuric acid, phosphoric acid, nitric acid and nickel ions (the polishing tank is a stainless steel tank, the tank wall is dissolved in the polishing process, and the nickel ions enter polishing solution). As the time of dripping is limited, one ton of aluminum material is polished, and the amount of the mixed acid brought into the water washing tank reaches 250-350 Kg. These spent acids are typically treated with lime to produce calcium sulfate and calcium phosphate. The treatment mode has high cost, large waste residue amount and ammonia nitrogen discharge.

The invention changes the traditional treatment after mixing the cleaning water into online classification treatment, avoids mixing the cleaning water with the cleaning water in the coloring tank and the hole sealing tank, and forms nickel-containing solid waste after treatment. The design concept of the traditional process is unreasonable, in figure 1, 11# and 14# are nickel-containing bath solution, aluminum is colored and hole-sealed and then directly enters four flowing rinsing baths of 12#, 13#, 15# and 16# to bring nickel-containing wastewater into a wastewater center to pollute cleaning water for other processes of the whole oxidation line; after mixing, these nickel-containing wastewaters are reprocessed and discharged to a standard level, with considerable difficulty, cost and resulting nickel-containing solid waste. The method needs to be improved urgently, the traditional mixed treatment method is replaced by the online classified individual treatment, and the environmental protection cost is reduced;

the invention changes the traditional cleaning water flowing in the polishing 4# groove into high-pressure atomization spraying cleaning, greatly reduces the cleaning water, saves the treatment cost and lays a solid foundation for online classification treatment and equipment miniaturization. And the 2#, 3# and 4# rinsing tanks are arranged behind the 1# polishing tank to clean residual polishing solution carried out by the polishing tank and protect the 5# ash removal tank. Tap water enters from the No. 4 tank, and is discharged from the No. 3 and No. 2 tanks and is reversely connected in series, the water consumption is about 2.0 to 3.0 tons per ton of wood, the water consumption is too large, and the discharged wastewater contains sulfuric acid, phosphoric acid and nitric acid, so that the environmental protection treatment pressure is increased; according to the invention, the No. 2 and No. 3 rinsing tanks are changed into the no-flow rinsing tank, and the No. 4 flowing rinsing tank is changed into the high-pressure atomization spraying tank, so that the cleaning water is greatly reduced, and a foundation is laid for online recovery of polishing waste liquid and miniaturization of recovery equipment;

the method abandons the traditional concept of passively treating the wastewater and the waste residues, treats the polishing wastewater and the waste residues from the aspect of recycling, changes hazardous wastes into valuable chemical resources, greatly reduces the treatment cost, and realizes the maximization of the value utilization of the phosphorus-containing chemical products. The traditional process design concept is that a polishing tank 1 is tank liquor containing phosphorus and ammonia nitrogen, aluminum materials are polished and then directly enter three flowing water washing tanks 2#, 3# and 4# to bring wastewater containing phosphorus and ammonia nitrogen into a wastewater center to pollute cleaning water of other procedures of the whole oxidation line; the wastewater center neutralizes, precipitates and presses the wastewater to obtain solid waste residue containing phosphorus and nickel, and discharges ammonia nitrogen; the national ministry of environmental protection has clearly specified that the massive waste residues containing phosphorus and nickel are dangerous wastes. And precious phosphorus resources are wasted while the environmental protection cost is paid. The extensive production mode is urgently needed to be improved, the No. 2 and No. 3 grooves are set as non-flowing water washing interception grooves, polishing solution is actively intercepted, special equipment is configured, phosphorus-containing products are recycled on line, waste is changed into valuable, and the resource utilization of hazardous waste is realized.

The method for recovering the compound fertilizer from the aluminum industry polishing solution is a new technology which is created after unprecedented system research is carried out on the polishing treatment process with large waste water and waste residue amount and huge environmental protection pressure of the existing aluminum processing enterprises after the production confusion of the aluminum processing enterprises is fully known and the polishing treatment process is researched and developed for many years.

The invention is realized according to the following theoretical basis and quantitative and qualitative analysis.

Theoretical basis of method and system configuration for recycling compound fertilizer from polishing and cleaning wastewater in aluminum industry

Taking three-acid polishing as an example, the polishing tank control indexes are as follows: 30 wt.% of sulfuric acid, 65 wt.% of phosphoric acid, 5 wt.% of nitric acid, 100-. The traditional production mode is as follows: polishing the aluminum material for 20-120 s, then hanging and dripping for less than 20s, and entering a No. 2 flowing water washing tank; cleaning for 1min, dripping for 30s, and entering a No. 3 flowing water washing tank; cleaning for 1min, hanging and dripping for 30s, and entering a No. 4 flowing water washing tank; cleaning for 1min, and hanging and dripping for 30s to finish the polishing and water washing process.

According to the requirement of the invention for intercepting polishing solution on line, the high-pressure atomization spray tank is provided with the storage tank, so that the cleaning water is reduced, and the recovery amount of waste water is reduced. Taking a mixture of polishing solution and water intercepted by the first no-flow rinsing tank, adding liquid ammonia, and carrying out the following chemical reaction:

2H₂SO₄+3NH₃＝NH₄HSO₄+(NH₄)₂SO₄

3H₃PO₄+6NH₃＝NH₄H₂PO₄+(NH₄)₂HPO₄+(NH₄)₃PO₄(1)

HNO₃+NH₃＝NH₄NO₃

Al³⁺+PO₄ ^3-＝AlPO₄↓ (or other heavy metals)

3Ni²⁺+2PO₄ ^3-＝(Ni)₃(PO₄)₂↓

The reaction proceeds to NH with increasing liquid ammonia addition₄H₂PO₄(pH4.5)→(NH₄)₂HPO₄(pH6.5-7.5)→(NH₄)₃PO₄(pH14.0) and AlPO increased with the increase in pH of the reaction mixture₄Gradually separated out. When the pH value is 6.5-7.5, the dosing is stopped. Filtering the aluminum phosphate and the nickel phosphate to obtain the product containing (NH)₄)₂SO₄、(NH₄)₂HPO₄、NH₄H₂PO₄And NH₄NO₃The mixed solution is concentrated and crystallized to produce compound fertilizer products. Besides sodium and potassium, the solubility of other heavy metal phosphates is very low, so that the heavy metals contained in the compound fertilizer can reach the standard.

Second, method and system for recovering compound fertilizer from polishing and cleaning wastewater in aluminum industry

After the non-flowing water is retained, the polishing solution is retained by the first non-flowing water washing tank and the second non-flowing water washing tank, the polishing material is sprayed by the high-pressure atomization spraying tank, the polishing solution is further retained, and the spraying water flows into the storage tank for later use. When the polishing material is produced in the interception mode, the acid concentration of the cleaning solution in the first no-flow water washing tank is continuously increased, the temperature is increased, the density is increased, and the polishing material gradually loses luster due to no-flow water washing. In order to maintain the polishing brightness, it is necessary to control the acid concentration and temperature of the first no-flow water washing bath. Because phosphoric acid is not easy to titrate accurately, the density of the first no-flow rinsing bath is used for monitoring the acid concentration, and the on-site operation is easy.

1. Influence of different densities (acid concentrations) of the no-flow water washing interception tank of the first no-flow water washing tank on the brightness of the polished material

Fixing the temperature of the first non-flowing rinsing bath at 50 ℃, producing a polished material, performing non-flowing rinsing in the first non-flowing rinsing bath and the second non-flowing rinsing bath, performing spray rinsing, drying, detecting the density (detected at normal temperature) of the first non-flowing rinsing bath and the brightness value (GU) of the polished material, and obtaining the results shown in Table 1:

brightness of light	1.0	1.1	1.2	1.3	1.4	1.5	1.6
								Density of	663	654	646	632	541	465	343

Table 1 shows the effect of the different densities of the bath solutions (at 50 ℃ C.) in the first no-flow water bath on the brightness of the polished materials. Table 1 shows that the density of the bath solution (acid concentration) in the first no-flow rinsing bath has a serious influence on the polishing brightness, and the acceptable control range is that the density of the bath solution in the first no-flow rinsing bath is not more than 1.3g/cm³Otherwise, the polishing material is severely lost.

2. Influence of different temperatures of bath solution of the first no-flow rinsing bath on brightness of the polishing material

The density of the bath solution in the first fixed no-flow rinsing bath was 1.3g/cm³And producing a polished material, spraying and washing the polished material after the non-flowing water of the first non-flowing water washing tank and the second non-flowing water washing tank, airing, and detecting the temperature (DEG C) of 2# and the brightness value (GU) of the polished material, wherein the results are shown in table 2:

brightness of light	10	20	30	40	50	60	70
								Temperature of	680	664	648	636	635	565	443

Table 2 shows the bath solution (1.3 g/cm) of the first no-flow water washing bath³Density) of the polishing material. Table 2 shows that the temperature of the bath solution in the first no-flow rinsing bath has a serious influence on the polishing brightness, and the acceptable control range is that the temperature of the bath solution in the first no-flow rinsing bath is less than or equal to 50 ℃, otherwise, the polishing material is seriously lost. Because the temperature of the polishing tank is about 110 ℃, the temperature of the first stagnant water washing tank and the second stagnant water washing tank is raised by the brought polishing liquid during production, and therefore cooling systems need to be arranged in the first stagnant water washing tank and the second stagnant water washing tank to ensure that the temperature is lower than 50 ℃, and the brightness of the polished material is protected.

3. Solid-liquid separation of aluminum ions and nickel ions in the bath solution of the first no-flow rinsing bath to produce aluminum phosphate and nickel phosphate

Taking 1L of the first non-flowing water washing tank (density 1.3 g/cm)³) Adding liquid ammonia according to the formula (1), cooling while stirring until the pH value of the reaction liquid is 6.5-7.5. Gradually turbid reaction liquid according to the formula (1), stopping adding the medicine when the pH value is 6.5-7.5, standing for 2 hours, and precipitating a layer of phosphoric acid at the bottom of a beakerAluminum white solid and a small amount of nickel phosphate. And (3) carrying out solid-liquid separation on the reaction product, rinsing solids, and drying to obtain aluminum phosphate and nickel phosphate products.

4. Concentrating and crystallizing the separated liquid to generate the N-P compound fertilizer

And taking 1000g of the separated liquid, concentrating, crystallizing, drying and grinding to obtain 453g of the ammonium sulfate-ammonium phosphate-ammonium nitrate-containing N-P compound fertilizer, wherein the content of cured substances in the liquid compound fertilizer is 45.3 percent, and the content of water is 54.7 percent.

5. Adding powdered bagasse (water content is less than or equal to 10%) to produce organic-inorganic composite fertilizer

Taking 1000g of the liquid compound fertilizer with the water content of 54.7%, adding 10g of dried fresh vinasse, gradually adding dry powdery bagasse (the water content is less than or equal to 10%) until no water is dropped, wherein the using amount of the bagasse (the water content is less than or equal to 10%) is 250g, and the finished product is a granular organic-inorganic compound fertilizer, and after fermenting and composting for 50 days, blackening, decomposing and curing the bagasse (the water content is less than or equal to 10%). The retting plant is equipped with ventilation equipment to prevent the accumulation of methane from igniting and exploding. The method is suitable for local material production in the southern sugarcane production area.

6. Adding powdery straw slag (the water content is less than or equal to 10 percent) to produce organic-inorganic compound fertilizer

Taking 1000g of the liquid compound fertilizer with the water content of 54.7%, adding 10g of dried fresh vinasse, gradually adding dried powdery straw residues (the water content is less than or equal to 10%), until water does not drip, wherein the using amount of the straw residues (the water content is less than or equal to 10%) is 280g, the finished product is a granular organic-inorganic compound fertilizer, and after fermentation and retting for 50 days, the straw residues (the water content is less than or equal to 10%) are blackened, decomposed and cured. The retting plant is equipped with ventilation equipment to prevent the accumulation of methane from igniting and exploding. The method is suitable for local material production in northern corn production areas.

7. Adding powdered rice hull powder (water content is less than or equal to 10%) to produce organic-inorganic composite fertilizer

Taking 1000g of the liquid compound fertilizer with the water content of 54.7%, adding 10g of dried fresh vinasse, gradually adding dry rice hull powder (the water content is less than or equal to 10%) until no water drops, wherein the using amount of the rice hull powder (the water content is less than or equal to 10%) is 340g, the finished product is a granular organic-inorganic compound fertilizer, and after fermenting and composting for 50 days, the rice hull powder (the water content is less than or equal to 10%) is blackened, decomposed and cured. The retting plant is equipped with ventilation equipment to prevent the accumulation of methane from igniting and exploding. The method is suitable for local-material-source production in southern rice production areas.

It should be noted that the bagasse, straw residue and rice hull powder can be replaced by plant-derived organic waste residues and organic waste residues produced by processing agricultural and sideline products, such as straw, corn residue, beans, peanuts and other crop straw residues, and residual branch wood strip residue, fallen leaf residue, dried vine residue, weed residue, fruit hull residue, potato residue and beet residue in forestry production.

Thirdly, the invention relates to a system configuration for recovering compound fertilizer from polishing and cleaning wastewater in aluminum industry

The aluminum industry polishing and cleaning wastewater recovery compound fertilizer system configuration of the invention is shown in fig. 2 and fig. 3, and comprises a polishing tank 1, a first no-flow rinsing tank 2, a second no-flow rinsing tank 3, a high-pressure atomization spraying tank 4, an aluminum phosphate recovery system 100 and an N-P compound fertilizer recovery system 200 which are arranged in sequence;

the high-pressure atomization spraying tank 4, the second no-flow rinsing tank 3 and the first no-flow rinsing tank 2 are communicated in sequence, and the high-pressure atomization spraying tank 4, the second no-flow rinsing tank 3 and the first no-flow rinsing tank 2 are used for intercepting polishing liquid from the polishing tank 1;

the high-pressure atomization spraying tank 4 is connected with a storage tank 5 for storing the sprayed wastewater, and the high-pressure atomization spraying tank 4 is communicated with the second stagnant water washing tank 3 through the storage tank 5;

the storage tank 5 is communicated with the second stagnant water washing tank 3 through a pipeline, a second pump 6 is arranged on the pipeline, and the second pump 6 is used for pumping the spraying waste liquid in the storage tank 5 into the second stagnant water washing tank 3. A pipeline communicated between the second pump 6 and the storage tank 5 is provided with a fifth single-pass valve 05, a pipeline communicated between the storage tank 5 and the high-pressure atomization spraying groove 4 is provided with a fourth single-pass valve 04, and a pipeline communicated between the second pump 6 and the second no-flow rinsing groove 3 is provided with a sixth single-pass valve 06.

A second one-way valve 02 is arranged at the communication position of the first no-flow rinsing bath 2 and the second no-flow rinsing bath 3. After the water level in the first no-flow rinsing bath 2 is lowered, the bath solution in the second no-flow rinsing bath 3 can enter the first no-flow rinsing bath 2 through the second check valve 02, and the second check valve 02 can prevent the high-concentration bath solution in the first no-flow rinsing bath 2 from entering the second no-flow rinsing bath 3.

The first no-flow rinsing bath 2 is connected with a first pump 7 through a pipeline, and the first pump 7 is used for pumping out bath liquid in the first no-flow rinsing bath 2. When the concentration of the bath solution in the first no-flow rinsing bath 2 is high, the first pump 7 pumps the bath solution out, and the waste liquid is collected for centralized treatment. A first one-way valve 01 is arranged on a pipeline communicated between the first pump 7 and the first no-flow rinsing bath 2.

The system further comprises a cooling pipeline 8, wherein the cooling pipeline 8 sequentially passes through the first no-flow rinsing bath 2 and the second no-flow rinsing bath 3, and the cooling pipeline 8 is used for cooling bath liquid in the first no-flow rinsing bath 2 and the second no-flow rinsing bath 3. The arrangement of the cooling pipeline 8 can ensure that the bath solution of the two non-flowing washing tanks is at a lower temperature level, and the brightness loss of the polishing material is reduced.

The high-pressure atomization spray tank 4 is connected with a third pump 9, the cooling pipeline 8 is communicated with an inlet of the third pump 9 after passing through the second no-flow rinsing bath 3, and the third pump 9 is used for pumping water in the cooling pipeline 8 into the high-pressure atomization spray tank 4 to be used as spray water. The cooling pipeline 8 supplies water for the high-pressure atomization spraying groove 4, so that the cooling capacity of the two non-flowing washing grooves is improved to the maximum extent, and the pipeline structure of the system is simplified. And a third one-way valve 03 is arranged on a pipeline for communicating the third pump 9 with the cooling pipeline 8.

The method for recovering the compound fertilizer from the polishing and cleaning wastewater in the aluminum industry and the downstream of the system configuration are sequentially provided with an ash removal tank 10, a first flowing water washing tank 11, a second flowing water washing tank 12, an oxidation tank 13, a third flowing water washing tank 14, a fourth flowing water washing tank 15, a coloring tank 16, a fifth flowing water washing tank 17, a sixth flowing water washing tank 18, a hole sealing tank 19, a seventh flowing water washing tank 20 and an eighth flowing water washing tank 21. The cooling duct 8 is connected in sequence to the second flowing water wash tank 12, the fourth flowing water wash tank 15, the sixth flowing water wash tank 18, and the eighth flowing water wash tank 21, and supplies water to these flowing water wash tanks. The seventh valve 07, the eighth valve 08, the ninth valve 09, and the tenth valve 010 are provided in the piping between the cooling piping 8 and the second flowing water wash tank 12, the fourth flowing water wash tank 15, the sixth flowing water wash tank 18, and the eighth flowing water wash tank 21, respectively. The first flowing water washing tank 11 is communicated with the second flowing water washing tank 12; the third flowing water washing tank 14 is communicated with the fourth flowing water washing tank 15; the fifth flowing water washing tank 17 is communicated with the sixth flowing water washing tank 18; the seventh running water wash tank 20 and the eighth running water wash tank 21 are communicated. The water washing wastewater in the first flowing water washing tank 11, the third flowing water washing tank 14, the fifth flowing water washing tank 17 and the seventh flowing water washing tank 20 flows into the wastewater center for centralized treatment.

The aluminum phosphate recovery system 100 comprises a reaction tank 101, a fifth pump 102, a liquid ammonia tank 103 and a filter press 104, wherein the reaction tank 101 is communicated with a first pump 7, the fifth pump 102 is arranged at the lower outlet of the reaction tank 101, the liquid ammonia tank 103 is communicated with the lower part of the reaction tank 101 through a pipeline, the filter press 104 is communicated with the outlet of the fifth pump 102 through a pipeline, the outlet of the fifth pump 102 is communicated with the upper part of the reaction tank 101 through a circulating pipeline 105, and the fifth pump 102 is used for circulating the liquid in the reaction tank 101 through the circulating pipeline 105 and pumping the materials in the reaction tank 101 to the filter press 104.

An eleventh valve 011 is arranged on a pipeline of an inlet of the fifth pump 102 communicated with the reaction tank 101. A thirteenth valve 013 is provided to the circulation line 105. A twelve-position valve 012 is arranged on a pipeline of the liquid ammonia tank 103 communicated with the reaction tank 101. A fourteen-gauge valve 014 is provided in the piping between the reaction tank 101 and the filter press 104. The pipeline between the fifth pump 102 and the eleventh valve 011 is communicated with the liquid ammonia tank 103 through a pipeline, so that the liquid ammonia tank 103 is communicated with the reaction tank 101. The reaction tank 101 is provided with an electric stirrer.

The N-P compound fertilizer recovery system 200 comprises a recovery tank 201, a seventh pump 202 and a filter 203 which are sequentially communicated, wherein the seventh pump 202 is used for pumping materials in the recovery tank 201 into the filter 203, a liquid outlet of the filter press 104 is communicated with the recovery tank 201, the bottom of the recovery tank 201 is provided with a sixth pump 204, and an outlet of the sixth pump 204 is communicated with the circulating pipeline 105.

A seventeen valve 017 is arranged on a pipeline between the recovery tank 201 and the seventh pump 201. And a fifteen-grade valve 015 is arranged on a pipeline of the recovery tank 201 communicated with the six-grade pump 204. And a sixteen-number valve 016 is arranged on a pipeline for communicating the six-number pump 204 with the circulating pipeline 105. A thirteenth valve 013 is located on the conduit between the sixth pump 204 and the fifth pump 102. The recovery tank 201 is provided with an electric stirrer.

This recovery system of compound fertilizer still includes cooling system 300, and cooling system 300 includes cooling tower 301, No. four pump 302 and cooling cycle pipeline 303, and cooling tower 301 and No. four pump 302 all establish on cooling cycle pipeline 303, and cooling cycle pipeline 303's cooling zone is located retort 201, and No. four pump 302 is used for making the coolant liquid circulation in cooling cycle pipeline 303.

The method for recovering compound fertilizer from polishing and cleaning wastewater in aluminum industry and the operation flow of system configuration are as follows:

1. the operation process of the polishing wastewater interception system comprises the following steps: opening a seventh valve 07, an eighth valve 08, a ninth valve 09 and a tenth valve 10, opening the washing water in the flowing cooling pipeline 8, and cooling the first and second stagnant

water wash tanks

2 and 3; when the temperature of the first no-flow rinsing bath 2 is controlled to be less than or equal to 50 ℃, polishing is started; after the aluminum alloy is polished in a polishing tank for 20-120 s, trickling for 20 s; entering a first no-flow rinsing bath 2, rinsing for 60s and dripping for 30 s; entering a second no-flow rinsing bath 3, rinsing for 60s and dripping for 30 s; entering a high-pressure atomization spraying groove 4, spraying for 30s, and enabling spraying water to flow into a storage tank 5; finishing the operation process of the polishing solution wastewater interception system;

2. the operation flow of the polishing solution wastewater collection system is as follows: detecting the density of the first no-flow rinsing bath 2, when the density reaches 1.3g/m³When the polishing solution is used, the first check valve 01 and the first pump 7 are opened, and the polishing solution intercepted by the first no-flow rinsing bath 2 is pumped into the reaction tank; and a second pump 6, pumping the polishing solution retained by the storage tank 5 into a second no-flow rinsing bath 3, and returning the retained solution to the first no-flow rinsing bath 2 through a second one-way valve 02 to finish the operation flow of the polishing solution wastewater collection system.

And pumping the polishing solution intercepted by the first non-flowing rinsing bath 2 into a reaction tank, adding liquid ammonia according to an experimental result 3, and recovering the aluminum phosphate and the N-P compound fertilizer.

The method for recovering the compound fertilizer by adopting the polishing and cleaning wastewater in the aluminum industry and the method for preparing and recovering the compound fertilizer by the system comprise the following steps:

intercepting polishing wastewater: aluminum alloy sequentially passes through a polishing tank 1, a first no-flow rinsing tank 2, a second no-flow rinsing tank 3 and a high-pressure atomization spraying tank 4, polishing liquid carried by the aluminum alloy is intercepted by the first no-flow rinsing tank 2, the second no-flow rinsing tank 3 and the high-pressure atomization spraying tank 4, and when the water level in the second no-flow rinsing tank 3 is lowered, the spraying wastewater in a storage tank 5 is replenished;

collecting polishing wastewater: detecting the density of the bath solution in the first no-flow rinsing bath 2, when the density reaches 1.25-1.31g/cm³Collecting the bath solution of the first non-flowing rinsing bath 2, and feeding the bath solution into a reaction tank 101 to obtain polishing wastewater, wherein the polishing wastewater comprises phosphate ions, nitrate ions and sulfate ions;

recovering aluminum phosphate and liquid N-P compound fertilizer: and starting the fifth pump 102 to circulate the liquid in the reaction tank 101, adding liquid ammonia into the wastewater by the liquid ammonia tank 103 until the pH value is 6.5-7.5, stirring for reaction, cooling, pumping the solid-liquid mixture in the reaction tank 101 into a filter press 104 by the fifth pump 102 to separate the solid from the liquid, wherein the solid is aluminum phosphate and nickel phosphate, and the liquid enters a recovery tank 201 from an outlet of the filter press 104 to recover the liquid which is the liquid N-P compound fertilizer.

The method further comprises the following steps:

The method also comprises the steps of preparing the granular organic-inorganic compound fertilizer:

In the step of preparing the granular organic-inorganic compound fertilizer, firstly adding waste residues containing zymophyte into the liquid N-P compound fertilizer, then gradually adding the organic waste residues, uniformly mixing the mixture, and carrying out ventilation fermentation until the mixture becomes black to be a curing end point, thus obtaining the granular organic-inorganic compound fertilizer;

the organic waste residue is added until the mixture does not drip water. The process difficulty can be reduced by setting the addition amount of the organic waste residue and the curing end point.

3. the polishing solution wastewater collection system is arranged on line for the first time, and the first no-flow rinsing bath 2, the second no-flow rinsing bath 3 and the high-pressure atomization spraying bath 4 are responsible for collecting polishing solution wastewater brought out by the polishing bath 1 in a step manner and feeding the polishing solution wastewater into the reaction tank for later use. The polishing solution wastewater treatment method comprises the following steps of configuring a first no-flow rinsing bath 2, a second no-flow rinsing bath 3 and a high-pressure atomization spraying bath 4, wherein the concentration of acid in the polishing solution wastewater is high at the front and low at the back and is distributed in a step shape, and gradually recovering the trapped polishing solution;

4. an aluminum phosphate recovery system is arranged on line for the first time and is responsible for recovering aluminum in the polishing solution wastewater, and aluminum phosphate is generated through reaction to realize solid-liquid separation;

5. an N-P compound fertilizer recovery system is arranged for the first time and is responsible for pumping the supernatant in the recovery tank into a filter for treatment and subpackaging a compound fertilizer solution; pumping the precipitate at the bottom of the recovery tank into the reaction tank again for secondary recovery;

6. adding liquid ammonia into the polishing wastewater for the first time, recovering Al3+ by using the liquid ammonia, reacting to generate aluminum phosphate and nickel phosphate, determining that the reaction end point is when the pH value reaches 6.5-7.5, and performing solid-liquid separation to obtain the aluminum phosphate and liquid N-P compound fertilizer;

7. bagasse (the water content is less than or equal to 10%) is used for absorbing water in the liquid N-P compound fertilizer for the first time, and the organic-inorganic compound fertilizer is prepared by solid-liquid mixing. The liquid N-P compound fertilizer recovered according to the invention contains more than 50% of water, and the concentration and crystallization not only consumes energy, but also is not environment-friendly and increases the cost. The organic-inorganic compound fertilizer is produced by utilizing a large amount of sugar-making waste residues in a sugarcane production area, properly adding dry and fresh vinasse, introducing yeast and mixing the liquid N-P compound fertilizer recovered by the method, so that the energy consumption and the environmental protection cost of concentration and crystallization are saved, the application of bagasse (the water content is less than or equal to 10 percent) is developed, the problems of caking compound fertilizer and soil hardening are solved, and multiple purposes are achieved;

8. straw residues (the water content is less than or equal to 10%) are used for absorbing water in the liquid N-P compound fertilizer for the first time, and the organic-inorganic compound fertilizer is prepared by mixing solid and liquid. The liquid N-P compound fertilizer recovered according to the invention contains more than 50% of water, and the concentration and crystallization not only consumes energy, but also is not environment-friendly and increases the cost. The method has the advantages that a large amount of straw waste residues in a corn production area are utilized, the dried and fresh vinasse is properly added, the yeast is introduced, and the liquid N-P compound fertilizer recovered by the method is mixed to produce the organic-inorganic compound fertilizer, so that the energy consumption and the environmental protection cost of concentration and crystallization are saved, the application of the straw residues (the water content is less than or equal to 10 percent) is developed, the difficult problems of caking compound fertilizer and soil hardening are solved, and multiple purposes are achieved;

9. the rice hull powder (the water content is less than or equal to 10 percent) is used for absorbing the water in the liquid N-P compound fertilizer for the first time, and the organic-inorganic compound fertilizer is prepared by solid-liquid mixing. The liquid N-P compound fertilizer recovered according to the invention contains more than 50% of water, and the concentration and crystallization not only consumes energy, but also is not environment-friendly and increases the cost. A large amount of rice hull powder (the water content is less than or equal to 10%) in a rice production area is utilized, dry and fresh vinasse are properly added, yeast is introduced, and the liquid N-P compound fertilizer recovered by the method is mixed to produce the organic-inorganic compound fertilizer, so that the energy consumption and the environmental protection cost of concentration and crystallization are saved, the application of the rice hull powder (the water content is less than or equal to 10%) is expanded, the problems of compound fertilizer caking and soil hardening are solved, and the method has multiple purposes.

A method for recovering compound fertilizer from polishing liquid for reducing slag in aluminum industry relates to a large source of a large amount of phosphorus-containing waste slag generated in aluminum processing industry, namely aluminum alloy polishing waste acid liquid. The waste acid is very large in quantity in some regions, such as a Foshan region, about 20 million tons of polishing acid are consumed annually, 6 million tons of sulfuric acid, 13 million tons of phosphoric acid and 1 million tons of nitric acid account for about half of 40 million tons of national dosage. The waste polishing acid is treated to generate over 100 million tons of phosphorus-containing waste residues every year in China, and simultaneously, about 5000 million tons of water is consumed. The waste water and the waste residue are treated, and meanwhile, precious phosphorus resources are wasted. The extensive production mode is urgently needed to be improved, and the invention is provided with two non-flowing water-washing interception grooves and high-pressure atomization spraying grooves to actively intercept polishing solution, recover phosphorus-containing products on line, change waste into valuable and realize the resource utilization of hazardous waste.

The method for recovering compound fertilizer from polishing and cleaning wastewater in aluminum industry and the method for recovering compound fertilizer configured by the system are further described by specific examples below.

Example 1 recovery of aluminum phosphate with liquid N-P compound fertilizer.

Intercepting polishing wastewater: after the aluminum alloy is polished in the polishing tank 1 for 20s-120s, trickling for 20 s; the aluminum alloy enters a first no-flow rinsing bath 2, is cleaned for 60s and trickles for 30s, a cooling pipeline 8 is arranged in the first no-flow rinsing bath 2, and the production temperature of the first no-flow rinsing bath 2 is controlled to be less than or equal to 50 ℃; then, the aluminum alloy enters a second no-flow rinsing bath 3, is rinsed for 60s and trickles for 30 s; then the mixture enters a high-pressure atomization spraying groove 4 and is sprayed for 30s, and spraying water flows into a storage tank 5; finishing the interception of the polishing solution wastewater; when the water level in the first flowing water washing tank 2 is reduced, the water in the second non-flowing water washing tank 3 is replenished; when the water level in the second no-flow rinsing bath 3 is lowered, the spraying wastewater in a liquid storage tank 5 communicated with the high-pressure atomization spraying bath 4 is replenished;

collecting polishing wastewater: detecting the density of the bath solution in the first no-flow rinsing bath 2, when the density reaches 1.25-1.31g/cm³Collecting the bath solution of the first no-flow rinsing bath 2, namely polishing wastewater, wherein the polishing wastewater comprises phosphate ions, nitrate ions, sulfate ions and nickel ions; wherein, the preferable liquid density of the tank 2 of the first no-flow water washing tank reaches 1.29-1.31g/cm³The bath solution is collected, and it is further preferable that the density of the bath solution in the first no-flow water washing bath 2 is 1.30g/cm³Collecting the bath solution;

and (3) recovering aluminum phosphate: opening valve No. eleven 011 and valve No. thirteen 013, closing valve No. fourteen 014; starting a No. five pump 102, and circulating the liquid to be reacted in the reaction tank 101 through a circulating pipeline 105; starting a fourth pump 302, starting a cooling tower 301, and cooling the reaction liquid by a cooling circulating pipeline 303; starting an electric stirrer in the reaction tank 101, opening a No. twelve valve 012, slowly adding liquid ammonia in a liquid ammonia tank 103, and reacting to generate ammonium salt of the mixed acid; adding ammonia while detecting pH value, stopping adding the ammonia when the pH value is not less than 6.5-7.5, and stirring for 30 min; cooling the reaction solution to below 40 ℃; opening the filter press 104, opening a fourteen-number valve 014, closing a thirteen-number valve 013, performing solid-liquid separation, recovering solid aluminum phosphate and nickel phosphate after rinsing, and enabling filtrate of the filter press 104 to flow into the recovery tank 201; completing the operation of the aluminum phosphate recovery system;

recovering the liquid N-P compound fertilizer: after the filtrate is precipitated for 2 hours in the recovery tank 201, opening a seventeen valve 017, starting a seventh pump 202, pumping the supernatant in the recovery tank 201 into a filter 203 for filtering, and subpackaging to obtain a liquid N-P compound fertilizer; and (3) closing the seventh pump 202 and the seventeen valve 017, opening the fifteenth valve 015 and the sixteenth valve 016, starting the sixth pump 204 and the electric stirring 2, pumping the sediment at the bottom of the recovery tank 201 into the reaction tank 101 again, and performing secondary recovery to complete the operation of the N-P compound fertilizer recovery system.

Example 2 the separation liquid of the liquid N-P compound fertilizer is concentrated and crystallized to produce the N-P compound fertilizer.

Taking example 1 when the density of the bath solution of the first no-flow water washing bath reaches 1.29-1.31g/cm³Collecting the tank liquor and obtaining 1000g of liquid N-P compound fertilizer under the condition that the medicine adding is stopped when the pH value reaches 6.5-7.5. Concentrating, crystallizing, drying and grinding to obtain 453g of the N-P compound fertilizer containing ammonium sulfate, ammonium phosphate and ammonium nitrate, wherein the solid content in the liquid N-P compound fertilizer is 45.3 percent, and the water content is 54.7 percent.

Example 3 a liquid N-P compound fertilizer was mixed with bagasse (moisture content: 10% or less) to produce a granular organic-inorganic compound fertilizer.

Taking example 1 when the density of the bath solution of the first no-flow water washing bath reaches 1.29-1.31g/cm³Collecting the tank liquor, obtaining 1000g of liquid N-P compound fertilizer with the water content of 54.7% under the condition that the pH value reaches 6.5-7.5 and the chemical addition is stopped, adding 10g of dried fresh vinasse, gradually adding dry powdery bagasse (the water content is less than or equal to 10%) until no water drops, wherein the using amount of the bagasse (the water content is less than or equal to 10%) is 250g, and obtaining a finished product of granular organic-inorganic compound fertilizer; fermenting for 60 days in a plant area equipped with ventilation equipment for composting, and blackening the compound fertilizer as a curing end point;

example 4 liquid N-P compound fertilizer is mixed with straw residue (moisture content is less than or equal to 10%) to produce granular organic-inorganic compound fertilizer.

Taking example 1 when the density of the bath solution of the first no-flow water washing bath reaches 1.29-1.31g/cm³Collecting the tank liquor, adding 1000g of liquid N-P compound fertilizer with the water content of 54.7% under the condition that the pH value reaches 6.5-7.5 and the medicine addition is stopped, adding 10g of dried fresh vinasse, gradually adding dried powdery straw residues (the water content is less than or equal to 10%) until no water is dropped, wherein the dosage of the straw residues (the water content is less than or equal to 10%) is 280g, and the finished product is granularAn organic-inorganic compound fertilizer; fermenting for 60 days in a plant area equipped with ventilation equipment for composting, and blackening the compound fertilizer as a curing end point;

example 5A liquid N-P compound fertilizer is mixed with rice hull powder (moisture content is less than or equal to 10%) to produce a granular organic-inorganic compound fertilizer.

Taking example 1 when the density of the bath solution of the first no-flow water washing bath reaches 1.29-1.31g/cm³Collecting the tank liquor, obtaining 1000g of liquid N-P compound fertilizer with the water content of 54.7% under the condition that the pH value reaches 6.5-7.5 and the medicine adding is stopped, adding 10g of dried fresh vinasse, gradually adding dry rice hull powder (the water content is less than or equal to 10%) until no water drops, wherein the using amount of the rice hull powder (the water content is less than or equal to 10%) is 340g, and the finished product is a granular organic-inorganic compound fertilizer; fermenting for 60 days in a plant area equipped with ventilation equipment for composting, and blackening the compound fertilizer as a curing end point.

The technical principle of the present invention is described above in connection with specific embodiments. The description is made for the purpose of illustrating the principles of the invention and should not be construed in any way as limiting the scope of the invention. Based on the explanations herein, those skilled in the art will be able to conceive of other embodiments of the present invention without inventive effort, which would fall within the scope of the present invention.

Claims

1. The preparation method is characterized by comprising the steps of sequentially arranging a polishing tank, a first no-flow rinsing tank, a second no-flow rinsing tank, a high-pressure atomization spraying tank, an aluminum phosphate recovery system and an N-P compound fertilizer recovery system;

the high-pressure atomization spraying groove, the second no-flow rinsing groove and the first no-flow rinsing groove are communicated in sequence and used for intercepting polishing liquid from the polishing groove; the high-pressure atomization spraying groove is connected with a storage tank for storing spraying wastewater, and is communicated with the second no-flow rinsing groove through the storage tank;

the aluminum phosphate recovery system comprises a reaction tank, a fifth pump, a liquid ammonia tank and a filter press, wherein the reaction tank is communicated with the first pump, the fifth pump is arranged at an outlet at the lower part of the reaction tank, the liquid ammonia tank is communicated with the lower part of the reaction tank through a pipeline, the filter press is communicated with an outlet of the fifth pump through a pipeline, an outlet of the fifth pump is communicated with the upper part of the reaction tank through a circulating pipeline, and the fifth pump is used for circulating the liquid in the reaction tank through the circulating pipeline and pumping materials in the reaction tank to the filter press;

the N-P compound fertilizer recovery system comprises a recovery tank, a seventh pump and a filter which are sequentially communicated, wherein the seventh pump is used for pumping materials in the recovery tank into the filter, a liquid outlet of the filter press is communicated with the recovery tank, the bottom of the recovery tank is provided with a sixth pump, and an outlet of the sixth pump is communicated with a circulating pipeline.

2. The aluminum industry polishing and cleaning wastewater recovery compound fertilizer system configuration of claim 1, further comprising a cooling system, wherein the cooling system comprises a cooling tower, a fourth pump and a cooling circulation pipeline, the cooling tower and the fourth pump are both arranged on the cooling circulation pipeline, a cooling section of the cooling circulation pipeline is located in the reaction tank, and the fourth pump is used for circulating cooling liquid in the cooling circulation pipeline.

3. The aluminum industry polishing and cleaning wastewater recovery compound fertilizer system configuration as claimed in claim 1, wherein a No. two one-way valve is arranged at the communication position of the first no-flow rinsing bath and the second no-flow rinsing bath, the storage tank is communicated with the second no-flow rinsing bath through a pipeline, a No. two pump is arranged on the pipeline, and the No. two pump is used for pumping the spray waste liquid in the storage tank into the second no-flow rinsing bath;

the first no-flow rinsing bath is connected with a first pump through a pipeline, and the first pump is used for pumping out bath liquid in the first no-flow rinsing bath.

4. The aluminum industry polishing and cleaning wastewater recovery compound fertilizer system configuration as defined in claim 1, further comprising a cooling pipeline, wherein the cooling pipeline passes through the first no-flow rinsing bath and the second no-flow rinsing bath in sequence, and the cooling pipeline is used for cooling bath liquids in the first no-flow rinsing bath and the second no-flow rinsing bath.

5. The aluminum industry polishing and cleaning wastewater recovery compound fertilizer system configuration as defined in claim 4, wherein the high-pressure atomization spray tank is connected with a third pump, the cooling pipeline passes through the second stagnant water wash tank and then is communicated with an inlet of the third pump, and the third pump is used for pumping water in the cooling pipeline into the high-pressure atomization spray tank as spray water.

6. The method for preparing and recovering compound fertilizer by adopting the system for recovering compound fertilizer from polishing and cleaning wastewater in aluminum industry as claimed in claim 1 is characterized by comprising the following steps:

collecting polishing wastewater: detecting the density of the bath solution in the first non-flowing water washing bath until the density reaches 1.25-1.31g/cm³Collecting the bath solution of the first non-flowing rinsing bath and feeding the bath solution into a reaction tank to obtain polishing wastewater, wherein the polishing wastewater comprises phosphate ions, nitrate ions, sulfate ions and nickel ions;

7. The method for recovering compound fertilizer as claimed in claim 6, wherein the system further comprises a cooling pipeline, the cooling pipeline passes through the first stagnant water washing tank and the second stagnant water washing tank in sequence, and the cooling pipeline is used for cooling the tank liquor in the first stagnant water washing tank and the second stagnant water washing tank;

8. The method for recovering compound fertilizer according to claim 6, further comprising the steps of:

9. The method for recycling compound fertilizer according to claim 6, further comprising the step of preparing granular organic-inorganic compound fertilizer:

adding organic waste residues and waste residues containing zymophyte into the recovered liquid N-P compound fertilizer, fermenting and curing to prepare the granular organic-inorganic compound fertilizer, wherein the water content of the organic waste residues is less than or equal to 10 percent.

10. The method for recycling a compound fertilizer as claimed in claim 9, wherein in the step of preparing the granular organic-inorganic compound fertilizer, the waste residue containing the fermentation tubes is added to the liquid N-P compound fertilizer, then the organic waste residue is gradually added, the uniformly mixed mixture is subjected to ventilation fermentation until the mixture is black, and the aging end point is reached, so as to obtain the granular organic-inorganic compound fertilizer;

the addition amount of the organic waste residue is controlled until the mixture does not drip water.