Method for preparing monocalcium phosphate

FIELD: inorganic chemistry, chemical technology.

SUBSTANCE: invention relates to technology for preparing fodder calcium phosphates, namely to producing monocalcium phosphate. Method involves mixing wet-process phosphoric acid with a calcium-containing component in the presence of recycle, granulation and drying the product. Mixing process is carried out for two stages. At the first stage wet-process phosphoric acid with the concentration 62-65% of P2O5 is fed and process is carried out at recycle index = 1:(0.3-0.5) up to decomposition degree of calcium-containing raw = 0.89-0.92 at this stage. The second stage is combined with granulation and carried out its in high-speed mixer in water addition to obtain moisture in mixture 9.5-13%. The rate and time for mixing are regulated to provide the decomposition degree of calcium-containing raw = 0.93-0.99, and temperature at the next drying stage is maintained in the level 105-115°C. Method provides simplifying the process, reducing energy consumption and preparing product with the high content of P2O5 in water-soluble form and low content of fluorine.

EFFECT: improved method for preparing.

2 cl, 3 ex

 

The invention relates to the technology of production of feed phosphates of calcium, specifically to the production of monocalcium phosphate.

A method of obtaining calcium orthophosphate one-deputizing, including evaporation of phosphoric acid to the content of P2O565-67,5%, followed by neutralization of its calcium carbonate. The initial molar ratio of Cao/R2About5equal (0,95-1,0):1. The resulting mass is crushed to particle size of not more than 0.1 mm (Patent RF №2172717 CL 01 In 25/32, 2001).

However, in this method are mostly fine product, which is used in the food industry. Its use as a feed means is quite difficult due to its high piomote and segregation with other feed additives and organic feed.

The closest to describing the technical essence and the achieved result is another well-known method of obtaining feed phosphates of calcium, including mixing phosphoric acid with calcium-containing component in the presence of retur, granulation and drying of the product.

According to this method, as the calcium-containing component use calcium carbonate or lime, and phosphoric acid fed to the mixture contains 45% R2About5and 0.3% of F. the Mixing is conducted at a molar ratio of the AO:P 2About3equal to 1.3 to 1.6. At this stage receive mainly dicalcium phosphate. On stage mixing serves part of retur obtained after the stage of granulation and drying of the product. The mixture was fed to the stage of granulation and drying, and then treated with phosphoric acid to obtain phosphate and again carry out the drying at a temperature of 145-170°C. This technique allows to reduce the fluorine content in the product to 0.15-0.2% (A. C. of the USSR №1463733 CL 01 In 25/32, 1989).

Technologically, the method is quite cumbersome and time consuming as it requires the organization of two stages of mixing and two-stage drying of the product. Returnest process is quite high (1:3). All this requires additional energy consumption and cost of instrumentation. Furthermore, the method does not allow the production process to modify and adjust the size of the granules depending on customer requirements.

We have been tasked to create a large-tonnage production of feed calcium phosphate, devoid of the above disadvantages and to obtain a product with a high content of P2About5in water-soluble form and low fluorine content in the finished product.

The problem is solved in the proposed method of obtaining phosphate, comprising a mixture of phosphoric acid with calcium-containing component in outstay reture, granulation and drying of the product. In this way the process of mixing lead in two stages, the first of which serves a phosphoric acid concentration of 62-65% P2O5and the process is conducted at returnest equal to 1:0.3 to 0.5, to achieve the degree of decomposition of the calcium-containing raw material at this stage, equal to 0.89 to 0.92, the second stage of mixing combined with granulation and lead her in a high-speed mixer adding water to bring the moisture content of the mixture to 9.5-13%, (at the first stage, the moisture content of the mixture is 4-5%). The speed and time of mixing is adjusted so as to obtain the degree of decomposition of calcium-containing raw materials, equal 0,93 is 0.99, and the temperature at the subsequent stage of the drying support 105-115°C. as a calcium-containing component is used or calcium carbonate, or a mixture of lime, which amount in the mixture does not exceed 15% of the total mass of calcium-containing raw materials.

The first stage of mixing is carried out in double-shaft mixer at a speed of 0.5-0.8 m/s In the mixer impose concentrated phosphoric acid, calcium component and all necessary retur. The moisture content of the mixture is 4-5%. When the reaction is intense emission of CO2and due to this loosening of the mass. The first stage allows you to remove the foam and therefore enables the use of high-speed mixers small reaction volume. Modal indices of the first stage is aimed, on the one hand, for the greatest selection of CO2at this stage (the extent necessary for the decomposition of raw materials), on the other hand, obtaining a weight that allows you to create in the next stage the best conditions for the granulation of the product. Bringing the moisture content of the mixture in the second stage of the process, combining the mixture that is dayslounge calcium-containing raw material, and the granulation product, up to 9.5-13%, is necessary and sufficient for obtaining a conditional granulated product. Reducing it below the level of 9.5% worsens the conditions of granulation and increased more than 13% will cause an increase in energy consumption at the stage of drying and reduces the output of marketable fractions.

This process can be used in various designs of high-speed mixers, of different sizes, with different speed characteristics. In this regard, experimentally chosen such factors as speed and process time, and the regulating value in all cases is the degree of decomposition of calcium-containing raw materials. Maintaining the temperature of the material during drying 105-115°necessary and sufficient to produce the finished product with the desired final moisture content of 1.0 to 3.5%.

The method involves the use of calcium-containing raw materials of musicabout calcium lime. However, the amount of lime should not exceed 15% of the total mass of calcium-containing raw materials, as due to the growth temperature of decomposition yields the polyphosphates of the calcium, which leads to reduction of digestible P in the product.

Using the proposed method allows you to create intensive large-scale production, allowing the use of high-speed mixers of various types with a small reaction volume. In almost developed technology solved the problem of foaming in a high-speed mixer. Small returnest process allows not only to reduce the amount of equipment, but also significantly reduce energy consumption for production. In addition, the resulting product phosphorus is mainly found in water-soluble form, the granules have a high strength. All of the above can be used as feed additives and makes the production of their highly profitable.

The method is illustrated by the following examples.

Example 1. Double-shaft mixer serves 6279,6 kg/h H3RHO462%, 3000 kg/h 96.8% of calcium carbonate and 2740, 8 kg/hour rature (Returnest 1:0,3). The speed of mixing 0.5 m/s Humidity of the mixture of 4%. The process is conducted within 1 minute of the Degree of decomposition of carbonate raw materials is 0.89. At this stage of the mixture together with water vapor is allocated 2368,1 kg CO2. Receiving the percent weight in the number 12020,4 kg/hour is served in a high-speed mixer volume ≈ 400 HP Circumferential speed of 12.5 m/s, the residence Time of 2-3 minutes In the mixer serves 591,2 kg/h H2O. Humidity of the mixture is 9.5%. The result is a granulated product with a degree of decomposition of the calcium containing raw materials 0,99 which is sent to the dryer drum. Drying temperature 105°C. the Dried product is sent for classification and cooling. Retur obtained after classification, served in a twin-shaft mixer.

The result 9316,1 kg/h of finished product containing Ptotal22,7%, Pwater-soluble21%, CAtotal14,8%, F of 0.18%. The granule strength of 23 kg/cm2.

Example 2. Double-shaft mixer serves 6279,6 kg/h H3RHO463%, 3000 kg/h 96.8% of calcium carbonate and 3554,9 kg/hour rature (Returnest 1:0,4). The speed of mixing 0.6 m/s Humidity of the mixture to 4.5%. The process is conducted within 1 minute of the Degree of decomposition of carbonaceous raw material is 0.9. At this stage of the mixture together with water vapor is allocated 2527,7 kg CO2. The resulting mass in the number 12674,9 kg/hour is served in a high-speed mixer volume ≈400 HP Circumferential speed is of 20.0 m/s, the residence Time of 2-3 minutes In the mixer serves 625,5 kg/h H2O. Humidity of the mixture is 11%. The result is a granulated product with a degree of decomposition of the calcium-containing raw materials of 0.93, which voltage is ablaut in the clothes dryer. Drying temperature of 110°C. the Dried product is sent for classification and cooling. Retur obtained after classification, served in a twin-shaft mixer.

The result 8887,3 kg/h of finished product containing Ptotal22,7%, Pwater-soluble21%, CAtotal14,8%, F of 0.18%. The strength of granules 32 kg/cm2.

Example 3. Double-shaft mixer serves 6279,6 kg/h H3RHO465%, 3000 kg/h 96.8% of calcium carbonate and 4599,9 kg/hour rature (Returnest 1:0,5). The speed of mixing 0.8 m/s Humidity of the mixture of 5%. The process is conducted within 1 minute of the Degree of decomposition of carbonate raw materials is 0.92. At this stage of the mixture together with water vapor is allocated 2447,9 kg CO2. The resulting mass in the number 13799,7 kg/hour is served in a high-speed mixer volume ≈400 HP Circumferential speed of rotation is 25.2 m/s, the residence Time of 2-3 minutes In the mixer serves 1268,9 kg/h H2O. Humidity of the mixture is 13%. The result is a granulated product with a degree of decomposition of the calcium containing raw materials 0,97 which is sent to the dryer drum. Drying temperature 115°C. the Dried product is sent for classification and cooling. Retur obtained after classification, served in a twin-shaft mixer.

The result 8874,5 kg/h of finished product containing Ptotal22,7%, Pvodarac work 21%, CAtotal14,8%, F of 0.18%. Granule strength 35 kg/cm2.

1. The method of obtaining phosphate, comprising a mixture of phosphoric acid with calcium-containing component in the presence of retur, granulation and drying of the product, characterized in that the process of mixing lead in two stages, the first of which serves a phosphoric acid concentration of 62-65% R2About5and the process is conducted at returnest equal to 1:0.3 to 0.5, to achieve the degree of decomposition of the calcium-containing raw materials, equal to 0.89 to 0.92 at this stage, the second stage of mixing combined with granulation and lead her in a high-speed mixer adding water to bring the moisture content of the mixture to 9.5-13%, speed and time of mixing is adjusted so as to obtain the degree of decomposition of calcium-containing raw materials, equal 0,93 is 0.99, and the temperature at the subsequent stage of the drying support 105-115°C.

2. The method according to claim 1, characterized in that as the calcium-containing component is used or calcium carbonate, or a mixture of lime, which amount in the mixture does not exceed 15% of the total mass of calcium-containing raw materials.



 

Same patents:

FIELD: industrial inorganic synthesis.

SUBSTANCE: monocalcium phosphate, widely applied in agriculture, is prepared by mixing extraction phosphoric acid with calcium-containing component followed by granulation and drying of product. During mixing of components, appropriate temperature and moisture are maintained to ensure viscosity of mixture 3-7 mPa*s, and granulation and drying are carried out simultaneously in drum-type granulator drier. Calcium-containing component is either calcium carbonate or mixture thereof with limestone, whose does not exceed 15% of total weight of calcium-containing raw material. Moisture content in worked out drying agent leaving drum-type granulator drier equals 70-80 g per 1 kg dry air.

EFFECT: simplified process flowsheet, enabled granule size control, and increased strength of granules.

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FIELD: industrial inorganic synthesis.

SUBSTANCE: monocalcium phosphate, widely applied in agriculture, is prepared by mixing extraction phosphoric acid with calcium-containing component followed by granulation and drying of product. During mixing of components, appropriate temperature and moisture are maintained to ensure viscosity of mixture 3-7 mPa*s, and granulation and drying are carried out simultaneously in drum-type granulator drier. Calcium-containing component is either calcium carbonate or mixture thereof with limestone, whose does not exceed 15% of total weight of calcium-containing raw material. Moisture content in worked out drying agent leaving drum-type granulator drier equals 70-80 g per 1 kg dry air.

EFFECT: simplified process flowsheet, enabled granule size control, and increased strength of granules.

3 cl, 3 ex

FIELD: inorganic chemistry, chemical technology.

SUBSTANCE: invention relates to technology for preparing fodder calcium phosphates, namely to producing monocalcium phosphate. Method involves mixing wet-process phosphoric acid with a calcium-containing component in the presence of recycle, granulation and drying the product. Mixing process is carried out for two stages. At the first stage wet-process phosphoric acid with the concentration 62-65% of P2O5 is fed and process is carried out at recycle index = 1:(0.3-0.5) up to decomposition degree of calcium-containing raw = 0.89-0.92 at this stage. The second stage is combined with granulation and carried out its in high-speed mixer in water addition to obtain moisture in mixture 9.5-13%. The rate and time for mixing are regulated to provide the decomposition degree of calcium-containing raw = 0.93-0.99, and temperature at the next drying stage is maintained in the level 105-115°C. Method provides simplifying the process, reducing energy consumption and preparing product with the high content of P2O5 in water-soluble form and low content of fluorine.

EFFECT: improved method for preparing.

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24 cl, 2 dwg, 1 tbl, 4 ex

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SUBSTANCE: anticorrosive pigment comprises , in mass per cents, 3.0-4.7 of calcium chromate and waterless dicalciumphosphate as the balance.

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3 cl, 1 tbl, 1 ex

FIELD: chemistry.

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2 cl, 3 ex

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