Extraction method of rare-earth metals from phosphogypsum

FIELD: metallurgy.

SUBSTANCE: invention can be used in the technology of obtaining the compounds of rare-earth metals at complex processing of apatites, and namely for obtaining of concentrate of rare-earth metals (REM) from phosphogypsum. Method involves sorption of rare-earth metals. At that, prior to sorption, phosphogypsum is crushed in water so that pulp is obtained in the ratio Solid : Liquid=1:(5-10). Sorption is performed by introducing to the obtained pulp of sorbent containing sulphate and phosphate functional groups, at the ratio of Solid : Sorbent=1:(5-10) and mixing during 3-6 h.

EFFECT: increasing REM extraction degree to finished product.

5 tbl, 5 ex

 

The invention relates to a process of producing compounds of rare earth elements by integrated processing of Apatite, in particular the production of concentrates of rare earth metals (REM) of phosphogypsum.

The method for extracting rare earth elements (RU 2225892, publ. 20.03.2004,) [1]. The method comprises leaching of phosphogypsum by sequential processing of multiple portions of phosphogypsum sulfuric acid solution with a concentration of 20-25% at W:T=2-3, the translation of rare earth elements in the solution, crystallization of REE concentrate from the solution obtained by leaching, which is carried out at a temperature of 20-80With the introduction of the leaching solution of concentrated sulfuric acid to its content in the solution is not less than 30%. Leaching of lanthanides from postopera solutions of sulfuric acid medium concentrations allows you to select the lanthanides from the leaching solution in the form of sulfate concentrate, which does not require the use of expensive extractants or surface-active substances.

There is also known a method for extracting rare earth elements from phosphogypsum (the Influence of the main process parameters on the efficiency of leaching of rare earth elements from phosphogypsum sulfuric acid / Amindian, Nfroce, Lambertino, Wedgeworth, Mccollow // Journal of applied chemistry, 1976. - v.49. No. 3. - S-638.) [2].

Solenopsae [2] the lanthanides are extracted from the phosphogypsum, obtained by sulphuric acid processing of Apatite concentrate on mineral fertilizers. Leaching of the first portion of phosphogypsum exercise 2-6%solution of sulfuric acid at the ratio of liquid to solid 2-3. The leaching solution is separated and used for subsequent leaching portions of phosphogypsum. The concentration of sulfuric acid at each stage increases according to the relationwhere- increment in the concentration of sulfuric acid, wt.%, and- increment in the concentration of phosphorous pentoxide in the leaching of previous portions of phosphogypsum, g/l Solution leaching using not less than three times. The maximum concentration of sulfuric acid is 24 wt.%. The phosphogypsum residue washed with water. The washing solution used for leaching of phosphogypsum. Before leaching phosphogypsum is crushed to a particle size of 100 microns. The achieved result is to increase process efficiency by increasing the concentration of lanthanides in solution in 3 times (up to 3.7 g/l) while maintaining high recovery (average extraction for 4-5 stages is 32,65-38,68%).

The extraction of rare earth elements from phosphogypsum by known methods [1, 2] requires a high cost of reagents (salts, acids), as well as significant energy and truthstar the t when receiving concentrates, filtering and washing of rainfall. In addition, at this stage there is a loss of REM by cocrystallization with gypsum and deposition of double sulfates of REM. The use of inorganic acids for leaching of REE from phosphogypsum leads to a large share of the consumption of resources and increased negative environmental impact on the environment.

Closest to the claimed invention to the technical essence and the achieved result is "a Method of extracting rare earth metals from phosphogypsum", EN 2416654 C1, CL SW 59/00 publ. 20.04.2011) [3]. The method comprises leaching of phosphogypsum sulfuric acid solution with the translation of rare earth metals in solution. Before leaching carry out washing of phosphogypsum from phosphorus water. Leaching of phosphogypsum carried out with a solution of sulfuric acid at a concentration from 3 to 250 g/L. Extract rare earth metals from solution leaching is performed by concentrating them on the cation exchanger, removing from the cation exchange resin to produce commodity regenerate and return to a full cycle of leaching depleted in rare earth metals aqueous solution of sulfuric acid.

However, it is known that sulfate environment contributes to the re-deposition of dissolved REE in the form of sparingly soluble double sulphates, reducing the degree of recovery of REE from ostypes sulfuric acid (Komissarova, L.N., Shatsky V.M., Pushkin GY, and other Compounds of rare earth elements. Sulfates, SELENATES, Telerate, chromates. - Leningrad: Nauka, 1986. - 365 S.) [4].

The use of cation exchange resin containing sulfuric acid functional groups leads to a decrease in sobiraemosti REM due to competitive sorption of ions of impurities (CA, Mg, Fe, Al, ...), since it is known that the sorbents with sulfuric acid functional groups are not selective to ions of rare-earth metals (Kokotov Y.A. Ion exchangers and ion exchange. - Leningrad: Khimiya, 1980. - 152 C.) [5].

The present invention is to increase the degree of extraction of rare-earth metals in the final product while reducing the cost of implementation of the method and reduce the negative ecological impact on the environment in the process of practical implementation of the method. To solve the stated problem, the claimed method, according to which the phosphogypsum is crushed and dissolved in water at a ratio of TV:W=1:(5-10), sorption is carried out by introducing into the resulting slurry of the sorbent, containing sulfuric acid and phosphoric acid functional groups, to TV:sorbent=1:(5-10), the leaching is carried out at a stirring within 3-6 hours

In the proposed method the dissolution of phosphogypsum is due to the arrival of ions of hydrogen functional groups of the sorbent, so adding the inorganic acid is not required. No sir okisnoi environment eliminates the re-precipitation of dissolved REE in the form of sparingly soluble double sulphates, increasing the degree of extraction of REE from phosphogypsum. High selectivity to REM sorbent containing sulfuric acid and phosphoric acid functional groups leads to the subsequent improvement of the quality of the eluates and facilitate their further processing (Vfront, Linedev, Twimukye. Study of adsorption of scandium from hydrochloric acid solutions by chelating resin PUROLITE S-957 // Chemistry and chemical technology, 2010, T, 9, S-101) [6].

When the ratio W:T less than 5, there is formed a dense, poorly pomeshivaem pulp phosphogypsum, which complicates the process of sorption of REE. When the ratio W:T more than 10 sharply increased volumes of solutions, which leads to an increase in the number of equipment. At the same time, positive effects on extraction of REE is not observed. The maximum sobiraemosti REM achieved during sorption 3-6 hours. When the contact time is less than 3 hours the degree of REE extraction insignificant, when contact time is more than 6 hours increase the degree of extraction does not occur. With regard to TV:sorbent is less than 5, the degree of extraction of REE practically does not change. With the increase of this indicator over 10 extraction ratio decreases REM.

Thus, a new technical result achieved by the declared method is to increase the degree of extraction of REE and simplifying the process of extracting rare-earth metals from phosphogypsum.

The experimental is Stalnoy verification of the claimed method was carried out when removing phosphogypsum rare-earth metals, namely, the entire group of lanthanides, yttrium and scandium. Their total content was determined by the method of emission spectral analysis with inductively coupled plasma. As a sorbent containing sulfuric acid and phosphoric acid functional groups, used the cation exchanger S-957 (PUROLITE LTD). Can be used as ion-exchange resin Diphonix production Eichrom Technologies.

Example 1. Took a portion of phosphogypsum 20 grams (in terms of absolutely dry), crushed, put into the reactor and filled it with water to the ratio of W:T=5, after which the resulting slurry was added to the sorbent in the amount of 4 grams (in terms of dry weight) and kept under stirring for 5 hours at room temperature. Have experience with the same conditions, but without addition of the sorbent. The research results are summarized in table 1.

Example 2. Took a portion of phosphogypsum 20 grams (in terms of absolutely dry), crushed, put into the reactor and poured it in different amounts of water, after which the resulting slurry was added to the sorbent in the amount of 4 grams (in terms of dry weight) and kept under stirring for 5 hours at room temperature. The research results are given in table 2

Example 3. Took a portion of phosphogypsum 20 grams (in terms of absolutely dry), were crushed, placed in the reaction is the PR and filled it with water to the ratio of W:T=5, then the resulting slurry was added to the sorbent in the amount of 4 grams (in terms of dry weight) and kept under stirring for 3, 5, 6, 7, and 9 hours at room temperature. The research results are summarized in table 3.

Example 4. Took a portion of phosphogypsum 20 grams (in terms of absolutely dry), crushed, put into the reactor and filled it with water to the ratio of W:T=5, after which the resulting slurry was added to the sorbent in the number 1,42; 2; 3,33; 4,0; 5,0; 6,67 (the ratio of solid : sorbent is respectively 14, 10, 6, 5, 4, 3) grams (in terms of dry weight) and kept under stirring for 5 hours at room temperature. The research results are summarized in table 4.

Example 5. Took sample of phosphogypsum 20 grams (in terms of absolutely dry), crushed, put into the reactor and filled them with water to the ratio of W:T=5, after which the resulting slurry was added sorbents in the amount of 4 grams (in terms of dry weight) and kept under stirring for 5 hours at room temperature. The research results are summarized in table 5.

From the data of tables 1-5 shows that the degree of extraction of rare-earth metals in the final product is not less than 60%. While non-use of inorganic acids for leaching of REE from phosphogypsum reduces the specific consumption of resources and negative ecologicas the e impact on the environment.

The method of extracting rare earth metals from phosphogypsum, including sorption of rare earth metals, characterized in that before the sorption of phosphogypsum are crushed in water to obtain slurry at a ratio of TV:W=1:(5-10), sorption is carried out by introducing into the resulting slurry of the sorbent, containing sulfuric acid and phosphoric acid functional groups, with a ratio of TV:sorbent=1:(5-10) and stirring for 3-6 hours



 

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