SU947147A1 - Process for producing feed precipitate - Google Patents

Description

() THE RATE OF OBTAINING FEED PRECIPITATION

This invention relates to a technology for the production of mineral feed additives. A known method for producing a feed precipitate from apatite nitrate (phosphate) extraction includes freezing calcium nitrate, separating alkali metal silicofluoride salts, treating the liquid phase with ammonia to pH 3.5, followed by separating the precipitate and obtaining a precipitate from. liquid phase and part of frozen calcium nitrate. The closest to the proposed technical essence and the achieved result is a method of obtaining feed precipitate by decomposition of fluorine-containing phosphate raw materials, first with nitric and then sulfuric acids, followed by preliminary separation of the resulting phosphoric acid (EPA) with alkali metal salts, processing the resulting solution with ammonia at pH C , 2-5.0 and part of the calcium salt to the molar ratio CaO / P-Og 0.08-0.16, separating the liquid phase from the precipitate and precipitating it with the remaining amount oli calcium known methods. Calcium nitrate is used as a calcium salt, which is obtained by dissolving phosphomel with nitric acid at pH 0. An insoluble residue, which is a low-percentage REE concentrate, is sent for further processing in order to recover REE. The known method allows the production of feed precipitate to be organized using native calcium apatite (phosphate) for these purposes and increasing the extraction from EPA to feed precipitate up to 80. The disadvantages of this method are the inefficient use of nitric acid (dissolution of phosphomel) and low yield of p2. in feed precipitate (). The purpose of the invention is to reduce the cost of the process by using nitric acid to extract P from apatite and increase the yield of co-precipitate. The goal is achieved by the fact that in the method of obtaining the feed precipitate, which includes decomposed; when the initial molar ratio in the solution is 1.6-2.2 and pH 1.2-2.5) and the preliminary defluorization is carried out by contacting the initial solution with a precipitate, half ennym on le treatment with ammonia solution. Moreover, preliminary defluorization is carried out at pH (-0.2) -0.7. The creation of a CaO / P O molar ratio of 1.6–2 in the initial fluorine-containing phosphoric acid solution makes it possible to exclude the operation of introducing calcium from the side either as natural calcium-containing minerals, or as a soluble calcium salt nor calcium salate, for which additional nitric acid is consumed. A special operation is also not required — freezing out calcium nitrate, which complicates the process. A given molar ratio of CaO / 1.6-2.2 can be obtained by decomposing apatite (phosphate) at such expenses of nitric and sulfuric acids, which, at a high opening of useful components, provide an excess of calcium (for example, in apatite, the molar ratio of CaO / P O 3,3) in the form of calcium sulfate. It can also be implemented by separate decomposition of apatite (phosphate) according to nitric acid and sulfuric acid schemes and mixing the resulting solutions to a predetermined CaO / P Oj ratio. The creation of the specified molar ratio in the initial solution ensures the obtaining of the feed precipitate but is not in itself sufficient for achieving the purpose of the invention of the shadow, i.e., reduce the cost of production. If you leave only this distinctive feature, and then carry on the process according to the known, then at pretreatment with ammonia to pH k, 25, 0, at least 80% of the total tg will be separated into a so-called fertilizer precipitate. OD P zschegos in the original solution. Therefore, the implementation of the proposed method is impossible without the second essential feature - the treatment of the initial fluorine-containing phosphate solution with ammonia at pH 1.22, 5. The effect obtained from the use of this distinctive feature is that even at the indicated pH values in the system under study, phosphoric acid solutions are obtained in which the fluorine content (0.5 g / l) ensures the production of feed precipitate corresponding to the standard ( fluorine content 0,2). The second significant feature, providing deep defluorization, creates conditions for a sharp decrease in the yield of fertilizer precipitate of fluorophosphate product) and thus maintains the yield of f / j in the feed precipitate at the level of the known. However, this figure is insufficient. To increase the yield of P o. to precipitate, excluding the use of alkali metal salts for preliminary defluorization of salts, it is necessary to contact the starting fluorine-containing phosphoric acid solution with the precipitate obtained after treating the solution with ammonia at pH 1.2-2.5, contact pH 0.2-0.7. as a result of the use of this feature, the fluorine content in this operation decreases in the liquid phase by a factor of 2-3. In addition, along with the defluorization, the bulk of the precipitate separated at pH 1.2-2.5 occurs, which leads to the return to the initial solution of the main amount of the precipitated product in the fluorophosphate product when the solution is treated with ammonia. The insoluble residue separated from the liquid phase is a fluorine-rare-earth concentrate (FRA) with F, into which almost all REE and all

fluorine contained in the initial solution.

Thus, the essential differences of the proposed method are in close relationship, characterized by a new-previously unknown set of features that create new positive properties.

Example 1. 100 g of apatite are pulverized into 186 ml of working solution (content 7.3%). Within 30 minutes, 111 ml of 7% nitric acid are introduced into the pulp, and then during the same time, 23 ml of 92% sulfuric acid. The pulp is deagitated at the level of 80 C. After filtration, a ml (1.33, Vt content is 159 g / l; F 11 g / l) of the main filtrate (initial phosphate-acid solution) with a pH of 0.5 and g of wet sediment is obtained, which is washed with 180 ml of water in the mode of double flushing, this gives 186 ml of circulating solution, which is sent to dispense the next portion of apatite, and 117 g of sludge and humidity Q% (dry content of sludge is 2%). The main filtrate is contacted with 95 g of wet sediment (moisture content b5%), the so-called fluorophosphate product, for 1 hour at 80 ° C. The pulp with pH 0.2 is concentrated, filtered, the precipitate is washed with kO ml of water, and 2k g of wet sediment is obtained (moisture 50%), the content in the dry sediment,%: I 5; 26; F U. Decantate, filtrate and washing are combined and 309 ml of a solution with a density of 1.39 is obtained, containing, g / l: fluorine 2.7; H. The solution is neutralized with ammonia to a pH of 1.9 (consumption of ammonia is 9.8 g). And agitate for 1 hour at. The pulp is filtered, 95 wet, unwashed fluorophosphate products are obtained, which are sent to contact with the initial phosphate solution in the next cycle, and 298 ml of filtrate with a density of 1.19, containing, g / l: 117; CaO 83; F 0.5. The latter is neutralized with ammonia to pH 0 (consumption of ammonia 7.3 g) and agitated at 80 ° C for 1 hour. The resulting slurry is filtered, the precipitate

washed with 140 ml of water in the mode of two continuous washing, dried at and get 70.5 g of dry sediment containing,%:

7.5; CaO 38; F 0.1 The recovery in the feed precipitate constitutes 88% of the phosphate solution and 85% of the apatite.

According to the method described above, tests were carried out on phosphoric acid solutions with different CaO / Bj O molar ratios, and at different pH treatments of phosphoric acid solutions with ammonia.

The results of regulation of the ratio of scientific research institutes CaO / PijOy of nitric and sulfuric acids during the decomposition of apatite, and the pH by ammonia consumption are presented in the table. From the table it follows that the most

acceptable results were obtained with a CaO / P JDg- molar ratio equal to 1.6-2.2, the ammonia treatment of the phosphoric acid solution was 1.2-2.5, and the pH of the release of PRZK was 0.2-0.7.

A decrease in the molar ratio CaO / to 1, 1 leads to a decrease in the recovery in feed precipitate to 60% and to the gluration of substandard fluorine in content.

Increasing the molar ratio to 2.4 reduces the content of the feed precipitate to.

Bringing ammonia treatment at pH 1.0 and a molar ratio of CaO / P O

2.0 does not provide sufficient purification of the phosphate solution from fluorine, which leads to an unacceptable high content of fluorine (0.7%) in the feed precipitate. PH increase

ammonia treatment to 2.7 reduces

and the quality of the feed precipitate, and

extract from apatite into it.

PH deviation

fluorophosphate product with the original

a phosphate solution leads to the same results as the pH deviation of the ammonia treatment.

Thus, the proposed method allows to reduce the cost of production due to the high extraction of the target product and simplify the cleaning of solutions from impurities, primarily from fluorine.

Claims (2)

1. A method of producing a feed precipitate comprising decomposing a fluorine-containing phosphate raw material with nitric and sulfuric acids, followed by the formation of a fluorine-containing phosphate solution, its preliminary) thorning, treatment with ammonia, separating the liquid phase from the precipitate and precipitating it, characterized in that, with the aim of reducing: .process due to the use of nitric acid to extract Pi.05 from apatite and increase the yield in the feed precipitate, the treatment with ammonia is carried out at the initial CaO / Pj C molar ratio in solution, equal to 1.6-2.2, and pH 1.2-2.5, and preliminary defluorization is carried out by contacting the initial solution with the precipitate obtained after processing ammonia solution. I 2. A method according to claim 1, characterized in that the preliminary defluorization is carried out at a pH of -0.2 0.7.