SU43375A1 - Method for producing superphosphates - Google Patents

Description

The invention relates to a process for the manufacture of fertilizer materials, in particular, a process for the manufacture of phosphate tukas.

Usually, in the manufacture of superphosphates and double superphosphates, the phosphorus-containing mineral is treated with strong sulfuric, phosphoric and other acids; the mineral and the acid are mixed in an open vessel equipped with a crib, after which the mass is allowed to settle and left in the premises for a certain time, usually about 24 hours. From here, the product is transported to storage sites.

Due to the strong affinity of sulfuric acid with the mineral, the reaction between both reagents proceeds rapidly and rapidly. Due to the violent and accelerated reaction, a solid final product is obtained, since the reaction mass rapidly passes from a liquid to a solid state.

The resulting product contains a significant amount of water n acid. In order to be transported to warehouses, it is usually desirable to shower it with scavengers, such as ground phosphate or lime. During storage, the material is sometimes subjected to grinding and peeling it for heating and further drying. This method, which requires multiple processing and large areas, is irrational, as it requires numerous personnel and large material costs.

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A further development of the method for producing superphosphates is the reaction of the decomposition of phosphates by acids under pressure (English Pat. М 156124); supply of phosphorus to the mixture. the cable is produced normally by compressed air through one nz of two concentric tubes, acid is fed through the second pipe (amer. pat.; & 1105304, ow. pat. no. 17280).

Drying of steam superphosphate is usually produced either in air, or in a kakum (English Pat. No. 9342).

The proposed invention allows to obtain a phosphate tuk with a minimum expenditure of time.

Basically, the method consists in that the mixture of phosphate rock with acid is loaded with Ео rotating autoclave, the latter is locked, rotated with EPP and after the material has been in the autoclave: -e long enough, release the resulting pressure and bring the pressure in the autoclave to below atmospheric for drying matrnnal. During this loading period, the autoclave is placed and dried to rotate. Due to the continuous rotation, the material in the autoclave comes into closest contact with the acid particles, and during vacuum drying, as a result of the rotation, the material breaks into lumps, which are rounded, creating an enlarged surface that facilitates evaporation of moisture, and the very final product forms grainy.

The reaction between tricalcium phosphate and acid proceeds rapidly and gives solid and gaseous products. In the method described, steam and gases generated in the autoclave create a pressure above atmospheric. The pressure can be stored in the autoclave or released from it by releasing the overpressure through the corresponding valve. The reaction between flour and acid can be accelerated by heating the mass. For this purpose, the autoclave can be supplied with a steam jacket or it can be let in directly into the autoclave, as will be explained later. Using a vapor directly or indirectly, the reacting mass provides sufficient heat to accelerate the reaction.

In a preferred embodiment of the process, the mass temperature is maintained between 130-150 during the stirring operation.

In the production process, flour and sulfuric acid are taken on a S2-100 ratio (for example, 82 foi. Acid 52 ° Weu per 100 pounds of phosphate flour; actual acid strength is 54 ° Weu). The mass is kept in an autoclave for about half an hour, during which flour is mixed. All this time, the mass should be thoroughly mixed by mechanical means by rotating the autoclave. Although the reaction products also contain monocalcium phosphate and calcium sulphate between other substances, the mass retains a more or less liquid consistency; if the autoclave is opened at the end of the mixing operation, it will turn out that the material does not have a spongy-like, plump structure, as in the case of the tukas made by known methods, but is a thick slurry in the kind of putty. It is possible that this is a result of too high a temperature that prevents the crystallization of calcium sulphate, as well as the fact that the reaction takes place in a closed vessel. from which water is not removed.

If you want to get a fat of varying fertilizing value, you can shred nitrogenous materials, such as ammonium sulphate or urea, or potassium materials, such as potash, celite, or carnallite, by mixing them with phosphate flour or their solution in sulfuric acid.

After half an hour, when the reaction had moved significantly, the conditions in the autoclave changed to produce a drying of the material. This is achieved, firstly, by blowing gases and bunks that accumulate during the reaction in an autoclave (if a pressure above the atmospheric pressure is applied). To release these gases and vapors, there is a special chapan on a rotating autoclave, which is opened for a period sufficient to bring the pressure to atmospheric. If desired, the autoclave can be cleaned by removing gases and vapors through the vacuum channel with a vacuum pump. In all cases, as soon as the pressure in the autoclave is reduced to atmospheric pressure, a vacuum is created in it. Continuing mechanical stirring continues throughout this period. mass by rotating the autoclave.

To facilitate the drying of the material, especially when not direct steam is used, the use of additional heating is recommended, but of course, in cases of

direct steam, when superheated steam is injected directly into the autoclave and remains there either under atmospheric pressure or under increased pressure, the heat of the mass itself may be sufficient to accelerate drying. When such additional heat is desired or necessary, to create it, pass circulating steam through the heating jacket of the autoclave under a pressure of about 50 pounds. When eGOM, the temperature during the process of the substance automatically drops due to evaporation of water. In typical cases, the temperature at the end of the vacuum period drops to 55-65 °. During the drying period, most of the water is distilled off and a part of it is held as crystallization water.

From this description it can be seen that the method is characterized by continuous mechanical pressing or turning the mass during loading, reaction and drying, and after about an hour of time the fertilizer tuk is completely ready. A titanium autoclave can be loaded in less than a minute and a half. This material is reacted at approximately one and a half hours either at a pressure of about 50 pounds or at atmospheric pressure or below atmospheric pressure. The pressure generated during the reaction is controlled within very wide limits and can be maintained at the required level by periodic or continuous blowing during the reaction. Under normal conditions, a pressure jacket of about 50 pounds is maintained in a steam jacketed autoclave during the reaction.

The drawing shows a typical embodiment of the apparatus used to implement the invention. The installation includes sources of acid and flour, means for attaching predetermined portions, components of the mixture, means for simultaneously loading the mixture of flour and acid into the rotating autoclave, and means for heating the mass in the reaction and for giving the necessary amount of heat to this mass, after reducing the pressure, it is used to dry the material. Heating can be done in different ways: the mass B of the autoclave is heated indirectly by steam circulating through the external karow shirt, and by other means the heat is reported by direct steam injection into the autoclave. The apparatus performing the first path is shown in the drawing. The installation consists of the following parts: an acid reservoir of a specific strength. The tank is equipped with a heating coil 2 connected to a suitable source of heating medium for the purpose of controlling the temperature of the acid to accelerate the separation. Nill the outlet end of the reserve is a filter 3 for cleaning the K5) slots intended for the reaction. Hot acid flows out of reservoir I through pipe 4 and its outflow rate is controlled by valve 5. Hot acid enters from Brujapa 1 into a graduated receiver 6, which is shown mounted on one of the ends of the rocker arm 7 in order to accurately show the portion of acid used for the batches. . A predetermined amount of acid is poured from the measuring device 6 through the pipeline 8, regulated by valve 9, into the tank 10. The measuring tank 6 can be disconnected from the tank 10; for this

The target tank 30 is provided with a funnel 11 with a tap 12, with which the tank 10 can be locked with pressure retained therein. A pipe line 13 with a valve 14 is connected to the upper part of the tank 10, which serves to admit air or other suitable pressure medium to accelerate the flow of acid from the tank to the autoclave.

Similarly, a finely ground phosphate mineral is accurately measured for each batch being loaded. Flour is fed through conduit 15 leading from a suitable source of supply to the funnel 16. Air is injected into the free and rapid flow of flour into it. The mains supply 17 connected to the compressed air source is connected to a branch 18, 19 and 20 with valves 18, 19 and 20, which serve to regulate the air flow. Compressed air is introduced through pipe 18 into & 16 through injectors 21. Exhaust under pressure of about 5 pounds. There is no material in the funnel 16 and in other places where the flies flow to aerate the latter. The mixture of flour with air makes it more fluid and ensures good flow throughout the system. Vyronka 16 has a conical bottom, the flour output from it is regulated by a fan 22 located in the outlet part of the funnel. A receiver 23 is located beneath Eorynka 16, in which the amount of flour to be fed to the mixing apparatus is carefully measured; The measurement is carried out using a yoke 24 mounted on the support 25. The measuring device has a conical bottom connected to the turbine with a gate 27 serving to regulate the flow of flour. To turn off the measuring device 23 during weighing, a hinged shutter 28 is provided.

A predetermined amount of flour, aerated in the funnel 16 and filled in a measuring device 23, is discharged through line 26, picked up by a pneumatic pump 29 and discharged through line 30 with valve 31 to the upper part of the charge funnel 32. The pump 29 can be of any suitable type, as long as it is transported flour fairly quickly. In order to communicate the flow of flour, air is injected under the said dalee on line 19.

The feed hopper for flour m32 has an npei shape of a truncated bone. At its lower end, it is connected by nozzle 33 to the air line 2E, and the air stream going into the crow is regulated by a crane 20. Veron 4a is equipped with wings or blades 34 mounted on the vertical axis of the Za passing through the matching backframe 36 at the top of the funnel and with its upper end-end cherdz a drive organ 37 with an energy source. Valve pipe propodo 33, regulated by valve 39, connected to the flour for flour, is connected with the upper corners; The sludge of flour in the valve chamber 40 can be removed through valve 41. When flour is flushed, valves 31 and 39 are open, valve 43 is closed. During this period, the deadlines 1 are in place; the blades remain stationary. When the crow is loaded, the valves 31 and 3G are closed and air is let in through the funnel 30, with the valve 20 open, and the vanes of the vanes 34 are turned into rotation.

The BnjCK of pressurized air enhances the flow of flour and at the same time the flour is driven by rotating vanes.

The lower end of the funnel 32 is connected to a special charging valve 42. The valve is polypropylene so as to mix and bring in close contact certain quantities of acid and flour.

 The spool 70 is turned on between the funnel 32 and the autoclave. This spool is designed to allow quick opening and closing and serves to stop the message between the autoclave and the loading end of the installation, forming a vacuum in the autoclave, resuming the same message with the autoclave, the body 70 quickly passing the mixture flour with acid.

The mixture of acid and flour is fed to an autoclave. The size and design of the autoclave may be different, however, it is recommended to use a horizontal rotating autoclave, lined with acid-resistant material, such as lead. The autoclave has an internal acid-resistant cable 72 and an external drum 71 with a heat-insulating gasket 73; the gap between them is the heating rub.: a skin for admitting the heating medium. The shredder is in open communication with hollow shafts 74 and 75 located at both ends of the autoclave. Hollow shaft 74 is connected to steam line 76 to allow steam to enter the jacket in order to warm the mass during the reaction or drying process. The autoclave may have a condensation trap 77 to which a drainage line 78 is connected, entering the hollow shaft 7a; from here, condensate is drained off line 79 away. The heating medium condensed during the process is collected in trawl 77 and discharged along lines 79.

The autoclave is moiter for rotating on a horizontal axis in any suitable way, for example in rings 80 in roller bearings 81 located at appropriate points in the autoclave. The rotation is communicated to the autoclave from a corresponding force source, for example, from a motor 82, through driving gears 83 and 84. Inside the autoclave is placed a partition 85 located in line with the outlet pipe 86 and intended to spray the material and prevent the acid mixture and the yuki exit the autoclave through the intake manifold. At the outer end of the autoclave, a pipe 87 is provided with a knee. 88 mounted inside the hollow shaft of the autoclave. Outside, this pipe communicates with pipe 89, regulated by valve 80, and also with steam pipe 91, adjustable valve 92. The steam pipe 91 communicates with the vacuum pump 93 through an absorption system, for example, spraying basch 94. A suitable condensation medium, for example, water is injected into the tower through conduit 95. The communication between the autoclave and the vacuum pump is regulated by valve 96.

A vent with a lid 97 is provided for discharging the contents from the autoclave. Underneath the autoclave there is a chest 98 into which the contents of the autoclave can be released. Conveyor 99 is located close to the chests, transporting the product to the place of further processing. To facilitate discharge, the autoclave is preferably raised in the form of a double cone with large diameters of 1 inside.

When it is required to make a mass of acidic phosphate, double superphosphate or other fertilizer mixture, the autoclave is first isolated from the charging end of the installation, closing valves 43 and 47. A given amount of hot acid and flour can be measured in measuring tanks and released into the receiver 10 for the acid and the funnel And for flour respectively. The progress of these receivers can occur while the former portion is reacted in an autoclave. After the acid has been released into the receiver 10, the valve 12 is closed, and the valve 14 is opened in order to apply pressure to the surface in the receiver 10. To accomplish this goal, air is pumped through line 13 to a pressure of 90 pounds.

In a preferred method, a partial vacuum is maintained in the autoclave during the loading period. For this purpose, the valves 92 and 98 open and the valves 43, 47 and 90 close. 93 pump in ai-.TOK. A vacuum is created. During this preliminary evacuation, steam may be injected through line 76 into the jacket of the autoclave to heat its interior. The transporter body 42 will be adjusted as described above to establish the desired proportions of flour and acid. This adjustment is preferably carried out so that the acid flow starts a little earlier than the flow of the flour and lasts a little longer than the flow of the flour; the last portion of the acid serves to clean the pipelines.

When the desired vacuum has been reached in the autoclave, the autoclave is set into rotation by starting the motor 82. If desired, the autoclave can be set to spin at the very beginning of the operation. At the beginning of the boot; During the operation, the vacuum is about 25 inches and at the end about 10 inches. A predetermined amount of flour, previously released and discharged into receiver 32, is blown with air passed through nozzles 33, and is driven by lrpatki 34. At this time, valves 31 and 30 are closed. For loading the material into the rotating autoclave, valves 43 and 47 are quickly and simultaneously opened. Under the influence of pressure on the acid and mukg and due to reduced accumulation in the autoclave, the flour flows out of the funnel 32 through the valve 43 and is wrapped with a conoidgly stream of acid. The acid and flour are displaced in the valve, as described above, and the passage r through the nozzle, in which the direction of their movement changes, as a result of which the mass receives an additional vortex. The mass then passes through the open valve 70, through the pipe 86, and with a force hits the septum 85. In the cream of this loading operation, the autoclave is rotated, and the mass is further mixed by the impact of the arc and the autoclave. Farther, the reluctance of the obstacle ;; t the mass to fall into the knee 88 and be carried away through the vacuum line. In normal operation, it takes from 1 to P / a min to transfer the contents of the funnel 32 from the reservoir a 10 to the autoclave.

Although the dimensions and capacity of individual parts of the installation can be different, it turned out that very good results are 5 to 8 feet. in diameter and og

15 to 20 feet. lengths Apply autoclave b foot. to diameter and 20 feet. length, it can be downloaded at a specified time, namely from J to li / j min. about 5 tons of material. During loading, the vacuum pump is working and the autoclave is in continuous rotation. The rotation speed of the atoclic can be varied over a wide range; It is recommended to inform him of the speed of 5 to 15 revolutions per minutes, preferably b revolutions per minute.

When all the material of one portion is immersed in an autoclave, valves 70 and 92 are closed, isolate the autoclave, and a vacuum pump is inserted in the vent. In normal operation, the steam in the jacket is kept under pressure of about 60 pounds, and the temperature of the mass during the transformation reaction is preferably between 150-160 °.

During the reaction period, the rotation of the autoclave continues and the mass is thoroughly mixed, freeing new surfaces of the flour particles for contact with the acid. During this process, the mass does not collapse into a dense body, but retains the consistency of putty or clay. The fact that the mass does not crystallize and does not condense is probably due to the fact that the temperature is maintained higher than that of calcium sulphate for crystallization, as well as preservation in the coya reaction zone. During the reaction, the mass is under pressure created by the process itself. But if it is desirable, the pressure inside the autoclave can be controlled by periodic opening of valve 90. In some cases, when the processed mineral has a high content of car6 O1-ata, it is recommended to gradually reduce the pressure ;.

The process can be carried out without pressure, i.e. at atmospheric pressure.

The material obtained by this method has the form of porous balls or individual grains and of the most diverse sizes, from pellets to balls several inches in diameter.

A distinctive feature of this product is. that grains or balls have hardness and high mechanical resistance. Their strength is so great that the material can withstand the crudest treatment, do not grind. Another striking difference in the product obtained from the autoclave is that its surface has a fine granular structure.

Due to the high mechanical strength of the product and the variety of grain sizes, it is immediately sifted and small screenings are immediately used as fertilizer. In a taxi, screening goes a significant part of the product, in some cases from 25 to 50% of the treated mass ..

The resulting product is also distinguished by other properties, as will be seen from the following.

Sulfuric acid and Floridian flour in the ratio of 86 to 100 by weight (acid was calculated at 52 ° B, but applied at 54 ° B) were loaded into the autoclave under the conditions mentioned above. The mass was .. interrupted by continuous mixing and heated with steam, about 50 pounds for half an hour, and the pressure in the autoclave was between 40 and 50 pounds. At the end of the process, the isiteclay evacuated for 3-5 minutes and the receiver was unloaded for about 35 minutes; vacuum is about 23 inches. During the drying period, the aiTO clav was continuously rotated so that the material was in motion; 50 pounds of steam were released into the heating jacket. The product was obtained with a low moisture content and consisted of an appropriate amount of very fine particles other than larger grains of exactly the same size. The material does not stick to the inner walls of the autoclave. The material was reversed to analysis one day after production and showed the following (in percent): in the calculation of 15, the ratio of acid to flour, PaOg,. . , 20,., X for the reaction. - Further, the remarkable feature of the Insoluble -. The 1.2 product is that it can be Water-soluble P-ZO. . . 15.3m grind immediately before or after sieving. This 1-nitrate solution of 3.5 is the opposite of the former Acidity .94.0 treatment method in an open vessel, since grinding Free psiO40.2, superphosphate immediately after making Free NdRO44.1Igpo in an open vessel is physically impossible. Chepech sem1, moreover, that the engineer was the product of the autoclave, easily and conveniently selected by the following Je - is with other fertilizers in the post office. .;. The product obtained by the proposed method moisture, 4.4 self, and has other properties that differ the entire work .... 20.2 from its superphosphate products, get soluble PjOs0.8m by methods with an open vessel. For established water-soluble PjOs14,9new these differences were made and the experience citrate PjOs4,5n different types. First of all, Acidity 96.0 was determined to determine the mechanical strength of the product Free H2SO40.0 according to the autoclave method and according to previous methods. Available NzRO4. 1.7 Here is the data analysis: Moisture Insoluble All Useful Free PaOg PjOsPjOs Acid Superphosphate former 11.95 17.68 0.7816.90 4.50 Autoplavate Superphosphate 7.00 20.32 0.88. 19,442.80 These two types of superphosphates were subjected to compression tests before grinding, with the following results: Autoclave superphosphate Sample J "1 ... 193 pound. on 1 square. in373 pounds. on 1 square. inch number 2.,. . 171 „„, ,, „289. . „„. , № 3 .... 173 ",. ,,", 423, ",. ,, on average 176 „„ „.362,. ,, Superphosphate from an open vessel: Fresh After 14 days Sample Jvfe 1. . . . 5.1 pounds on 1 square. inch 23 pounds. on 1 square. inch number 2 .... 15.6 „„. „, 37. ",". Number 3. ... 11.2. „„, .. 27 „„, „„ on average 10.3, „„ „, 29,. “. The advantages of superphosphate in the proposed method is 10 pounds. on 1 square. inch. According to the previous method, superphosphates according to the previous test. The tensile test showed, in particular, in a fresh state, the following results: the chickpea is still more from the table below. Autoclaved superphosphate ak has already been mentioned, it is known that fresh superphosphate from an open vessel cannot be Sample J 1. . .50 fun. on 1 square. inch, immediately r for processing. Therefore, ppprep- №2. ..40 ,, „„, their methods of phosphate production must be superphosphate from an open vessel, it was necessary to shower the fresh product with absorbing, il, etc., .. as materials such as ground phosphate mi-Ooraz and. No. 1 ... About fun. on 1 square. inch, eraloma. According to the table below, the average is - - i, ".,, The compressive force of the fresh autoclaved super- Another distinctive feature of autoclave phosphate is about 176 pounds. that 1 cr. inch toda superphosphate pgles its density. One is the same indicator for superphosphate but pre- fer. a foot of a high-grade superphosphate contains And, it is clear that it is fresh; The resulting product was under such conditions that it could be used as fertilizer immediately, and further, that after a certain period of storage, it still improves not only in terms of decreasing moisture, but also in terms of increasing the total and useful amount of phosphoric acid. Even for a short period of storage, free sulfuric acid completely disappears, and free phosphoric acid is reduced to a very small percentage. An outstanding feature of the process n product is high acidity, if at Fresh After 14 days