SU1386612A1 - Method of processing phosphate raw material - Google Patents

Abstract

The invention relates to methods for the decomposition of phosphate raw materials and can be used in the technology of obtaining complex fertilizers with the simultaneous utilization of rare-earth elements and fluorine. The aim of the invention is to increase the recovery rate of rare earth elements and fluorine into the filtrate. The goal is achieved by using a method of decomposing phosphate raw materials with nitric acid in the presence of sulfate ion as the source of sulfate ion using sulfuric acid, which is introduced at the decomposition stage in the amount of 5-10% of the amount supplied to the nitric acid. - acid decomposition. Using the proposed method allows to increase the degree of extraction of rare earth elements and fluorine into the filtrate and thus creates the opportunity to effectively utilize these elements. 1 tab. I cl

Description

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The invention relates to methods for the decomposition of phosphate raw materials and can be used in the technology of obtaining complex fertilizers with simultaneous utilization of rare-earth elements and fluorine.

The aim of the invention is to increase the recovery rate of rare earth elements and fluorine into the filtrate.

An example. . decomposition of 30 g phosphate flotation concentrate, containing,%: 30,8; CaO 47.5; C02 7.4; F 2.54; one and a half oxides () 2.4, including the oxides of rare earth elements O, 22, insoluble residue 5.6, use 64 g of 45% nitric acid and 2.7 g of 93% sulfuric acid, the amount of nitric acid 90%, sulfuric - 10% of the stoichiometric rate based on the decomposition of CaO phosphate (total acid rate is 100%). The decomposition process is carried out at 60 ° C for 40 minutes with constant stirring, at the end of the decomposition the insoluble residue is removed on a Buchner funnel, and the filtrate is sent for further processing. Filtration rate 0.027, extraction of phosphate raw material components into solution,%: 99.6; F 79.6; rare earth elements 83.2.

P and Measure 2, To decompose 30 g of phosphate concentrate of composition indicated in Example 1, a mixture of 67.7 g of 45% nitric acid in an amount of 95% of the stoichiometric rate and 1.3 g of 93% sulfuric acid are used. acids in an amount of 5% of stoichiometry (total acid rate is 100%). Decomposition and filtration are carried out as in Example 1. The filtration rate is 0.07 m / m H, the extraction of phosphate raw material components into solution,%:. PjOj 99.0; F 84.8; rare earth elements 87.5,

EXAMPLE 3 To decompose 30 g of phosphate concentrate of composition indicated in Example 1, a mixture of 64 g of 45% nitric acid in an amount of 90% of the stoichiometric rate and 2.7 g of 93% sulfuric acid in an amount of 10 are used. % of stoichiometry (total acid rate is 100%). Decomposition and filtration is carried out under the conditions specified in Example 1. The filtration rate is 0.142. h, the extraction of phosphate components in

solution,%:. 99.6; F 80.0; rare earth elements 82.0.

EXAMPLE 4 A mixture of 71.3 g of 45% nitric acid in an amount of 100% of the stoichiometric rate and 2.7 g of 93% sulfuric acid is used to decompose 30 g of the phosphate concentrate of the composition indicated in Example 1. in the amount of 10% of stoichiometry (total acid rate is 110%). The decomposition and filtration is carried out under the conditions specified in Example 1, the filtration rate is 0.213 h, the extraction of the components of the phosphate raw material into solution,%: 99.7; F 80.8; rare earth elements 82.7,

The results of carrying out the process of nitric acid decomposition of phosphohigrate concentrate in the proposed parameter ranges, as well as under the conditions of known methods (nitric – sulfuric acid decomposition with a significantly higher rate of sulfuric acid and nitric acid decomposition with the introduction of a phosphogypsum suspension) are listed in the table.

The introduction of sulfuric acid at the decomposition stage leads to the formation of calcium sulfate crystals and its partial precipitation, thus improving the structure of the insoluble precipitate. At the same time, fluorine and rare-earth elements practically do not enter the solid phase, which is a prerequisite for their subsequent extraction from the solution.

The degree of conversion of fluorine and REE to precipitate is directly proportional to the amount of calcium sulfate formed: the more sulfuric acid is introduced during the decomposition stage, the more calcium sulfate crystallizes and the more fluoride and REE in the crystallization process precipitate. In this case, fluorine is co-precipitated as CaSiF and CaB on the surface of CaS04 crystals} and REE isomorphically replacing calcium in the CaS04 crystal lattice.

The obtained data testify to the effectiveness of using small amounts of sulfuric acid additives (5-10%) in the nitric acid decomposition of phosphate to simultaneously reduce the loss of fluorine and REE with the sediment and their subsequent removal from solution, as well as to ensure good filtering properties of the insoluble residue.

313866

Claims (1)

Invention Formula A method of processing phosphate raw materials, including nitric acid decomposition in the presence of sulfate ion, separating the insoluble precipitate, obtaining a filtrate and processing it, characterized in that 12 in order to increase the degree of extraction of rare earth elements and fluorine into the filtrate, sulfuric acid is used as a source of sulfate ion, which is introduced at the decomposition stage in an amount of the amount of acid fed to the nitric acid decomposition stage. Nitric acid decomposition (100% HNOj,) According to the proposed method No filter - No undecided solids separation