CN108855152B - Catalyst for increasing soluble aluminum content of calcium aluminate powder and application method thereof - Google Patents

Abstract

The invention provides a catalyst for increasing the soluble aluminum content of calcium aluminate powder and an application method thereof. The soluble alumina content of the calcium aluminate powder can be increased by adding an external agent, thereby improving the product quality of the existing calcium aluminate powder. Improve market competitiveness. The present invention is prepared in the following manner: 72%wt of sodium fluorosilicate, 11%wt of sodium chloride, 11%wt of grass ash and 6%wt of sodium fluoroaluminate are weighed and then ground for 5 ‑8 minutes, fully mixing the four substances to obtain a composite catalyst. The present application utilizes the existing raw materials such as bauxite and limestone of calcium aluminate powder production enterprises, plus a small amount of cheap aluminum-containing substances and catalysts. It has the product quality of calcium aluminate powder to improve market competitiveness.

Description

Catalyst for increasing soluble aluminum content of calcium aluminate powder and application method thereof

technical field

The present invention relates to the field of calcium aluminate powder production, in particular to a method for increasing the soluble alumina content of calcium aluminate powder by adding external agents.

Background technique

Calcium aluminate powder is an ideal raw material for the production of basic aluminum chloride and polyaluminum chloride products. The main components are CaO, AL ₂ O ₃ , Fe ₂ O ₃ , which have strong activity. The use of acid-soluble one-step method to produce water purifier can save a lot of manpower, electricity, and greatly reduce costs, and has the advantages of simple process equipment. , easy to grasp and so on. In recent years, the global water pollution problem has become increasingly prominent and has become a severe challenge faced by many countries.

The production of calcium aluminate powder usually uses high-grade bauxite with alumina content of about 65%-70% and limestone with calcium carbonate content of about 95%. The ratio of the two is designed according to the reaction equation generated by calcium aluminate powder. Bauxite: limestone = about 100:175, which can be obtained by crushing and classifying after firing in the temperature range of 1250-1350 °C.

Most of my country's bauxite resources are diaspore type with high aluminum, high silicon and low aluminum-to-silicon ratio. Different from other parts of the world, more than 95% of bauxite in my country is of diaspore type, which is of medium grade. At present, the reserves of high-quality bauxite resources are becoming less and less. The development and utilization of low-grade bauxite (alumina grade between 55-60% wt) to prepare calcium aluminate powder water purifier material has broad market prospects.

Three kinds of bauxite raw materials used in the production of the enterprise were collected, and the test results are shown in Table 1: From Table 1, it can be seen that the alumina grades of the three kinds of bauxite, Bau-1 and Bau-2, are slightly higher, at 55-60%. between wt. According to the national standard GBT 24483-2009, the standard of bauxite ore should be compared with the DLK11-55 brand, but the national standard requires that the aluminum-silicon ratio of this brand should be at least greater than 11, so Bau-1 and Bau-2 are both unqualified bauxite ore , Bau-3 alumina grade and Al/Si ratio are worse.

Table 1 Chemical analysis results of main elements of bauxite samples

The content of all alumina in the calcium aluminate powder prepared by using the above-mentioned medium and low grade bauxite is about 45%. According to the method introduced in the national standard GBT 29341-2012 calcium aluminate for water treatment agent, the acid dissolution test was carried out on the calcium aluminate product of the enterprise. The laboratory analysis showed that the content of soluble alumina in the calcium aluminate product was about 39.5%. .

SUMMARY OF THE INVENTION

The invention provides a catalyst for increasing the soluble aluminum content of calcium aluminate powder and an application method thereof. The soluble alumina content of the calcium aluminate powder can be increased by adding an external agent, thereby improving the product quality of the existing calcium aluminate powder. Improve market competitiveness.

The technical scheme of the present invention is achieved in the following manner: a catalyst for increasing the soluble aluminum content of calcium aluminate powder is prepared in the following manner: 72%wt of sodium fluorosilicate, 11%wt of chlorinated Sodium, 11% wt of plant ash and 6% wt of sodium fluoroaluminate are weighed and then milled for 5-8 minutes, so that the four substances are fully mixed to obtain a composite catalyst.

The application method of the composite catalyst is carried out according to the following steps: according to the amount of raw meal powder, the ground waste alumina powder in an addition amount of 4% wt, the composite catalyst in an addition amount of 3% wt and The tap water is fully stirred to become a suspension, which is added dropwise to the surface of the raw meal powder, and the raw meal powder is fully stirred to make it evenly mixed, and then the pellet is formed, and then placed in a muffle furnace for calcination.

Preferably, the waste alumina is a powder that can pass through a 325 mesh screen after being ground.

The catalyst was added to the waste alumina at an addition amount of 10% wt, ground in a ball mill, and then the slurry was washed out, dried and pulverized to obtain a supported catalyst.

The application method of the supported catalyst is carried out according to the following steps: according to the amount of raw meal powder, the supported catalyst in an added amount of 4% wt is mixed with tap water, the slurry is stirred to a state of suspension, and the mixture is added dropwise. The suspension is added dropwise to the surface of the raw meal powder, and the raw meal powder is fully stirred to make it evenly mixed.

The present application utilizes the existing raw materials such as bauxite and limestone of calcium aluminate powder production enterprises, plus a small amount of cheap aluminum-containing substances and catalysts. It has the product quality of calcium aluminate powder to improve market competitiveness.

Detailed ways

A catalyst for increasing the soluble aluminum content of calcium aluminate powder is prepared in the following manner: 72%wt sodium fluorosilicate, 11%wt sodium chloride, 11%wt plant ash and 6%wt After the sodium fluoroaluminate is weighed, it is ground for 5-8 minutes in the grinding process (5-8 minutes in the grinding of the three-headed mill), and the four substances are fully mixed to obtain a composite catalyst. Its use process is as follows: according to the raw meal powder (raw meal powder is the material prepared during actual production, the specific mass ratio of each component is about: bauxite: limestone: coal = 50:35:15, coal is added in which the main In order to provide energy during the calcination process), 4%wt of the ground waste alumina powder, 3%wt of the composite catalyst and tap water were fully stirred to become a suspension, and added dropwise. To the surface of the raw meal powder, fully stir the raw meal powder to make it evenly mixed, then form a ball, and then put it in a muffle furnace for calcination.

Preferably, the waste alumina (referring to unqualified alumina produced by alumina production enterprises and falling material produced in production and transportation) is a powder that can pass through a 325-mesh screen after being ground.

In the present application, the principle of the catalyst is as follows: 1. The non-metallic ionic functional group has a lower boiling point and is easy to melt/gasify in a high temperature reaction, and the catalyst of the present invention reduces the system's The sintering temperature can cause defects in the lattice of insoluble aluminum, thereby increasing the dissolution rate of aluminum. 2. The catalyst can inhibit the formation of spinel phase with higher lattice activation energy, thereby reducing the formation of insoluble aluminum.

The application also discloses a supported catalyst, which is prepared in the following manner: adding the above-mentioned composite catalyst to waste alumina in an addition amount of 10% wt, adding water to a ball mill for grinding, and then washing out the pulp. Dry and powder to obtain a supported catalyst. Its use method is as follows: according to the amount of raw meal powder, mix the supported catalyst with the added amount of 4% wt with tap water, stir the slurry to a state of suspension, and drop the suspension dropwise onto the surface of the raw meal powder, The raw meal powder is fully stirred to make it evenly mixed, and then the pellets are formed, which can be calcined in a muffle furnace.

The catalyst of the present application can significantly increase the soluble alumina content of calcium aluminate clinker powder, and has better economic cost. It can be divided into two types: composite type and supported type according to the different compound forms of aluminum source and catalyst. This type of catalyst can stably improve the soluble alumina of calcium aluminate clinker powder under laboratory conditions or on-site conditions in enterprises. The content of the catalyst is 2-4%, and the materials and test equipment used to prepare the catalyst are listed in Table 2.

Table 2 Information table of materials and equipment required for the preparation of composite catalysts

serial number name Specifications Manufacturer Function 1 Waste alumina powder -- Enterprise provides Catalyst aluminum source 2 Sodium Fluorosilicate analytically pure Sinopharm Reagent catalyst component 3 Sodium chloride analytically pure Sinopharm Reagent catalyst component 4 plant ash Commercially available Sinopharm Reagent catalyst component 5 Sodium fluoroaluminate analytically pure Sinopharm Reagent catalyst component 6 Electronic balance BSA124S Sartorius, Germany Weighing tool 7 Three head grinder Catalyst processing 8 Planetary Ball Mill Catalyst processing 9 Blast drying oven 101A-2 Shanghai Experimental Equipment for drying 10 High-speed pulverizer 6202 Universal Asia Tianyuan Machinery for powder

Example 1: First, the waste alumina powder was ground, and the grinding condition was to weigh 15-20 g of a waste alumina sample with an electronic balance, add it into a mortar of a three-head grinding machine, and grind ore continuously for 15 minutes. The powder should all pass through a 325 mesh screen. The mesh number of this aluminum source can be effectively reduced by grinding waste alumina, and its specific surface area and surface activity can be improved at the same time.

Then prepare the composite catalyst component, first accurately weigh 72%wt of sodium fluorosilicate, then weigh 11%wt of sodium chloride, 11%wt of grass ash and 6%wt of sodium fluoroaluminate (four kinds of The total ingredients are 100% wt), after weighing, add them to the three-head grinder and grind for 5-8 minutes, so that the four substances are fully mixed. Finally, the ground catalyst powder is packaged and sealed for later use.

Based on 50 g of raw meal powder added, the preparation method of the corresponding composite catalyst is as follows: accurately weigh 2.0 g (4% addition amount) of ground waste alumina powder into the beaker, and then weigh 1.5 g of the prepared catalyst ( 3% addition amount) into the beaker. Add tap water and fully stir to become a suspension liquid, add dropwise to the surface of the raw meal powder through a dropper, and fully stir the raw meal powder to make it evenly mixed and then formed into pellets, which are then calcined in a muffle furnace according to the process conditions. That's it. The specific formula summary is shown in Table 3.

Table 3 Compound catalyst formula table

Example 2: In order to make the catalyst have more excellent use efficiency and a simpler preparation and addition method, this example uses the principle of mechanochemistry to produce a supported catalyst.

The preparation method of the supported catalyst is as follows: respectively weigh 55g of waste alumina powder (unground) and 5.5-6g of the composite catalyst prepared in Example 1 (the relative addition amount is about 10% wt), and put them into a 500ml ceramic ball mill jar. Add 60g of water to it, seal it tightly, put it in a position of the planetary mill, and put a counterweight tank of the same weight in its symmetrical position. Use a wrench to fix the two ball mill jars tightly and then start the grinding. The speed of the ball mill is set to 800rpm, and the grinding time is set to 30 minutes. After grinding, the pulp is washed out, dried and pulverized for use in subsequent experiments.

Take 50g of raw meal powder to test this type of catalyst as an example, directly weigh 2g of the prepared supported catalyst (4% wt addition amount) and put it into a beaker, add an appropriate amount of tap water and stir the slurry to a state of suspension, use dripping The catalyst liquid is added drop by drop to the surface of the raw meal powder, and the raw meal powder is fully stirred to make it evenly mixed and then formed into pellets, which can be calcined in a muffle furnace according to the process conditions.

The basic principle of this embodiment is: using the huge mechanical extrusion force and centrifugal force generated by the planetary ball mill during the grinding process, the composite catalyst and the aluminum source are fully squeezed and infiltrated during the grinding process, so that the aluminum source is in the grinding process. At the same time, the catalyst agent contaminates the surface of the aluminum source powder, so that the loading mode of the catalyst changes from the previous bulk catalysis to surface catalysis, which can greatly save the amount of catalyst added with higher cost.

The composite catalyst and the supported catalyst were used for testing. Each catalyst was tested in parallel with a parallel sample without catalyst for comparison. Each sample uses 60g of raw meal powder, and the use of composite catalyst requires the addition of 1.8g of catalyst and 2.4g of waste alumina, respectively. When using a supported catalyst, 2.4 g of catalyst needs to be added.

Embodiment 1 and embodiment 2 using method are as follows:

A muffle furnace with a set temperature curve or a muffle furnace with manual temperature control can be used. The heating process of the muffle furnace in this application is as follows: first dry the agglomerated wet material at 150 ° C for 30 minutes, and then transfer it to an upper limit of 1100 ° C. The muffle furnace was calcined at 580 °C for 30 minutes, and then heated to 900 °C for 30 minutes; finally, the sample was transferred to a muffle furnace with an upper limit of 1600 °C and at the set temperature (1250 °C--1350 °C ) sintered for 40 minutes and cooled to obtain clinker.

After the obtained clinker was sieved by vibration grinding powder, 15 g of sample was weighed and boiled at 100° C. for 60 minutes with 100 ml of hydrochloric acid. Finally, the laboratory personnel use the method for the determination of soluble alumina in the measurement of soluble alumina content introduced in the national standard GB/T29341-2012 "Determination of soluble alumina" to carry out titration analysis of the leachate to be tested and calculate the soluble alumina. content.

Four batches of experimental comparisons were performed, each containing a blank and a catalyst-containing sample. The specific test conditions and results are summarized in Table 4.

Table 4 Summary table of test results of test catalysts

It can be seen from the test results in Table 4 that at 1350 °C the samples were melted and damaged due to too high temperature, while at 1200 °C, the soluble alumina content of the composite catalyst was lower due to the too low test temperature. Under the condition of 1250°C, the supported catalyst can increase the content of soluble alumina by 1.5%, and the composite catalyst can increase the content of soluble alumina by more than 4%.

Table 5 Summary table of calcium aluminate sintering test results

It can be seen from Table 5 that after adding catalyst, the soluble aluminum content increased significantly.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of the present invention. within the scope of protection.

Claims (5)

1. The catalyst for improving the soluble aluminum content of the calcium aluminate powder is characterized by being prepared in the following way: weighing 72 wt% of sodium fluosilicate, 11 wt% of sodium chloride, 11 wt% of plant ash and 6 wt% of sodium fluoroaluminate, grinding for 5-8 minutes in grinding, and fully mixing the four substances to obtain the composite catalyst.

2. The catalyst for increasing the soluble aluminum content of calcium aluminate powder according to claim 1, characterized in that: the catalyst is added into waste alumina according to the addition amount of 10 wt%, water is added into a ball milling tank for grinding, and then ore pulp is washed out and dried and powdered to obtain the supported catalyst.

3. A method of using the catalyst of claim 1, comprising the steps of: according to the weight of raw material powder, fully stirring 4 wt% of grinded waste alumina powder, 3 wt% of compound catalyst and tap water to form suspension, dropwise adding the suspension to the surface of the raw material powder, fully stirring the raw material powder to uniformly mix the suspension, forming pellets, and calcining in a muffle furnace;

the raw material powder comprises 50 parts of bauxite, 35 parts of limestone and 15 parts of coal.

4. The method for using the catalyst according to claim 3, wherein: the waste alumina is a powder that can pass through a 325 mesh screen after grinding.

5. A method of using the catalyst of claim 2, characterized by the steps of: mixing the supported catalyst with the addition amount of 4 wt% and tap water according to the weight of the raw material powder, stirring slurry to a suspension state, dropwise adding the suspension to the surface of the raw material powder, fully stirring the raw material powder, uniformly mixing, then pelletizing and forming, and putting into a muffle furnace for calcining.