SU1313840A1 - Method for producing fertilizers from phosphate ores - Google Patents

Abstract

The invention relates to a technique for the nitric acid processing of phosphate raw materials into mineral fertilizers. The purpose of the invention is to improve the quality of the finished product by increasing the concentration and content of the digestible phosphates, as well as to intensify the filtration process of the nitric acid extract. The method involves treating the phosphate raw material with nitric acid, filtering the nitric acid extract to determine the insoluble residue, and before filtering, calcium nitrate solution is introduced into it in an amount corresponding to 0.2-0.3 kg of CaO per I g of the insoluble residue while holding the mixture 10–20 min; subsequent neutralization of the phosphorus-containing solution at pH 4.5–5.5; drying the neutralized suspension and granulation of the finished product; As a solution of calcium nitrate, it has been proposed to use a filtrate from the separation of neutralized time. 1 hp f-ly, 1 tab. $ (L 00 Eo 4

Description

113

The invention relates to a technique for the nitric acid processing of phosphate raw materials into mineral fertilizers.

The purpose of the invention is to improve the quality of the finished product by increasing the concentration and content of the digestible phosphates, as well as to intensify the filtration process of the nitric acid extract.

The method involves treating the phosphate raw material with nitric acid, filtering the nitric acid extract to separate the insoluble residue, and introducing a solution of calcium nitrate in an amount corresponding to 0.2–3.0 g of CaO per 1 g of insoluble residue before it is filtered. mixtures for 10–20 min, followed by neutralization of the phosphorus-containing solution at pH 4.5–5.5, drying the neutralized suspension and granulation of the finished product. As a calcium nitrate solution, a filtrate from separating the neutralized suspension is used.

Example 1. 100 kg of phosphorite (JJ3% PjOj, 29.4% CaO, 37% insoluble residue) are treated with 122.5 to nitric acid (54% HNO,). The nitric acid extract (222.5 kg) is mixed with 142 kg of filtrate from separating dicapium phosphate suspension to maintain a ratio of 0.2 g of CaO per 1 g of insoluble residue. The mixture is kept for 10 minutes. 364.5 kg of nitric acid extract are filtered and 85 kg of insoluble residue washed with 100 kg of water is separated. A phosphorus-containing solution and washings in an amount of 379.5 kg neutralize 9.0 kg of gaseous ammonia to pH 5.0 and the resulting suspension of dicalcium phosphate is separated on a filter. This gives 50 kg of wet dicalcium phosphate (47., 0 kg of dry), 100 kg of water and 438.5 kg of filtrate, which is divided into two streams: 142 kg are mixed with a nitric acid extract, and 296.5 kg - for recycling. The product contains 46.4%, total. and 44.5% yev. (96% of the digestible phosphates), and the removal of the insoluble sediment is 420 kg / m-h, respectively.

P. pmme R 2. 100 kg of phosphorite are treated with 122.5 kg of nitric acid. The nitric acid extract (222.5 kg) is mixed with 540 kg of filtrate from separating the suspension.

of calcium phosphate to maintain a ratio of 0.8 g of CaO to 1 g of insoluble residue. The mixture is kept 15. 762.5 kg nitric acid extract

filter and separate 80 kg of the insoluble residue washed with 100 kg of water. Phosphorus-containing solution and washings in the amount of 782.5 kg neutralize 8.5 kg of gaseous ammonia to a pH of 4.5. The resulting suspension of dicapropium phosphate is separated on a filter. You get 50 kg of wet washed 100 kg of water dicaption phosphate (47.5 kg dry) and 841 kg

the filtrate, which is divided into two streams: 540 kg is sent for mixing with nitric acid extract, and 301 kg for processing. The product contains 46% of the total. and 43.7% yev. (95% of the digestible phosphates), and the removal of the insoluble residue, respectively, 400 kg / m h.

Example 3. 100 kg of phosphorite (24.0% P, jOy, 41.5% CaO, 20% insoluble residue) are treated with 173 kg of nitric acid. The nitric acid extract (273 kg) is mixed with 760 kg of filtrate from separating the suspension of dicalcium phosphate to maintain a ratio of 3 g of CaO per 1 g of insoluble residue. The mixture is kept for 20 minutes. 973 kg of nitric acid extract is filtered and 50 kg of insoluble residue washed with 100 kg of water is separated. Phosphorus-containing solution and

The washings in the amount of 1023 kg neutralize 11.5 kg of ammonia gas to a pH of 5.5 and the resulting suspension of dicalcium phosphate is separated on the filter. In this case, 70 kg of wet dicalcium phosphate (46.5 kg of dry), washed with 100 kg of water and 1064.5 kg of filtrate are obtained, which are divided into two streams: 760 kg of filtrate are mixed with the nitric acid extract, and 364, 5 kg - for recycling. The product contains 46.5% of the total. and 45.6% yev. (98% of the digestible phosphate), and the removal is insoluble

the remaining residue is respectively 450 kg / hr.

Table B contains examples of process management in the predicted parameter ranges - (experiments 1-3) and beyond.

As can be seen from the table, the conduct of the process outside the limits

parameters (experiments 4-9) leads to a decrease in process performance.

A decrease in the ratio of g CaO per g of insoluble residue is less than 0.2 (test 4) leads to a decrease in process performance due to insufficient Ca

2+

one

in the turnover of the ionic solution.

An increase in the ratio above the stated limit (experiment 5) leads to a decrease in the process indices due to the high content of calcium ions in the working solution, leading to the destruction of the solvation shells

When the suspension time is reduced to 5 minutes (test 6), the removal of the insoluble residue is reduced due to the lack of time for coagulation. An increase in the residence time of more than 20 minutes (run 7) leads to a decrease in filtration rates due to the destruction of the coagulated particles of the solid phase.

A decrease in the pH value below the stated limit (experiment 8) leads to a decrease in the concentration in the final product and the content of the digestible phosphates due to the incomplete precipitation of dicalcium phosphate. Increase, 5 (experiment 9) is impractical due to the partial recrystallization of dicalcium phosphate to tricalcium phosphate and a decrease in the content of digestible phosphates.

Thus, the proposed method with respect to the prototype makes it possible to improve the quality of the product (the content of PjQs increases by 2.5-5.5%, and the forms to be assimilated - by 6-10%) due to a more complete separation.

insoluble residue; and neutralizing solutions for specific pH values. Only dicalcium phosphate precipitates out and is excluded from precipitation; the formation of three calcium phosphate binding part into an incompetent form

fO

mu This increases the removal of the insoluble residue to 380-450 kg / mh (instead of 50-60 kg / mh of the prototype), and also reduces the volume of the reaction equipment by 5-8 times due to a decrease in the amount of the reaction mass.

Claims (2)

1. Method of fertilizer production from phosphate ores, including their ob-. processing with nitric acid, filtering the nitric acid extract with separation of the insoluble residue, neutralizing the phosphorus-containing solution, essence of the neutralized suspension and granulation of the finished product, characterized in that, in order to increase the quality of the finished product by increasing the concentration of PjOj- and digestible phosphates, as well as the intensification of the filtration of nitric acid extract, before it is introduced a solution of calcium nitrate in the amount of 0.2–0.3 g CaO per 1 g of insoluble residue and filter the mixture 10-20 min, and the neutralization of the phosphorus-containing solution is carried out to a pH of 4.5-5.5. I 2. The method according to claim 1, which differs from the fact that as a solution of calcium nitrate is used, the filtrate is separated from the separation of the neutralized suspension. Editor M.Kelemes Compiled by V. Vilinska Tehred A. Kravchuk. Proofreader L. Patay Order 2178/24 Circulation 408 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, Uzhgorod, Projecto st., 4