Method of processing rare-earth phosphate concentrate

FIELD: chemistry.

SUBSTANCE: method of processing a rare-earth phosphate concentrate separated when neutralising a nitric-phosphoric acid solution obtained after breaking down apatite with nitric acid, includes treating rare-earth phosphate concentrate with nitric acid and separating the undissolved residue from the obtained rare-earth element nitrate-phosphate solution. After treatment, the undissolved residue is washed and rare-earth elements are extracted from the rare-earth element solution. The undissolved residue is washed with ammonium nitrate solution with concentration of 40-70 wt % in amount of 25 pts.wt per 1 pts.wt of the undissolved residue. The wash solution is combined with the rare-earth element solution fed for extraction, and the undissolved residue is taken for production of compound fertilisers.

EFFECT: high degree of extraction of rare-earth elements from the rare-earth phosphate concentrate while reducing consumption of ammonia at the step of neutralising the nitric-phosphoric acid solution, consumption of nitric acid and hydrogen peroxide when dissolving the rare-earth phosphate concentrate.

3 cl, 3 tbl, 4 ex

 

The invention relates to the processing of rare earth phosphate concentrate (or FRSC)obtained in the process of complex nitric acid processing of Apatite in complex fertilizers.

The extraction of rare earth elements in Apatite when nitric acid decomposition is made from nitrogen-phosphate solution of partial neutralization in the form of a rare earth phosphate concentrate (FRSQ), and the subsequent processing of the rare earth elements.

Known methods of processing FRSC by dissolving in nitric or hydrochloric acid, followed by precipitation of oxalates of the rare earth elements oxalic acid (nitrate Complex processing of phosphate rock. Edited Goldikova A. A. and Kopylova B. A. - L.: Chemistry 1982, S. 157-159; EN 2148019, 23.11.1998).

Disadvantages ways:

- the use of scarce and expensive reagent oxalic acid;

in the production process we form solutions containing excess of oxalic acid, the disposal of which in the production of complex fertilizers leads to deterioration of quality fertilizers.

A method of obtaining nitrate-phosphate solution of rare earth elements (REE) from FRSC suitable for subsequent extraction of REE extraction method. The method includes raspulpovka FRSC rastvorimo stage of leaching of the extractant, treatment with nitric acid, separating the resulting solution of the REE from the insoluble residue and the subsequent washing of the insoluble residue diluted solution of nitric acid with a concentration of 1.5 N (Moiseev, S. D. and other Extraction refining of rare earth phosphate concentrate obtained in the processing of Apatite. Chemical industry, No. 8, 1981, S. 472-475). Important when the extraction recovery of REE from nitrogen and phosphate solutions has a concentration of REE in solution, the presence in the solution of vysalivatel and the concentration of free nitric acid.

The disadvantage of this method is use for washing the insoluble residue containing significant amounts of rich REE liquid phase, the solution with a high water content, which leads to higher water content and lower content of REE in solution supplied to the extraction, and requires the creation of additional equipment for further processing.

The closest in technical essence (prototype) to the proposed method is a method of processing rare earth phosphate concentrate, isolated by neutralizing nitric-phosphoric acid solution obtained after dissection of Apatite nitric acid, including the processing of rare earth phosphate concentrate nitric acid, separating the insoluble is the STATCOM obtained from nitrate-phosphate solution of rare earth elements and washing of the insoluble residue nitrogen-phosphate solution with a flow rate ranging from 100 to 710 wt.h. 1 wt.h. the insoluble residue. The solution after leaching serves on stage ammonization for deposition FRSC (patent RU 2086507, 26.05.1992 year). The practical implementation of the method consists in mixing an insoluble precipitate to the original nitrogen-phosphate solution. The disadvantages of the method are:

- the need to separate insoluble precipitate of significant volumes of suspensions that require long-term sludge (over 8 hours) and filtering the thickened part of the resulting suspension;

- detachable residue from the stage of dissolution FRSC contains significant amounts of REE in the form of water-soluble nitrate salts is more than 10% of the REE from the quantity in FRSC; this number REE returns to the beginning of the production cycle FRSC (recycling), and therefore increases the consumption of the reactants to the deposition of an additional quantity of REE from nitrogen-phosphate solution and obtaining a solution of nitrate salts REE; recycle stream REE requires an increase in the consumption of ammonia in the stages of deposition FRSC, nitric acid and hydrogen peroxide in the stages of dissolution FRSC;

- separation of the insoluble residue in the form of a "collective" of precipitation together with crematorium sodium or calcium will lead to deterioration of the quality of these products and the impossibility of obtaining products without additional purification stages.

adaca invention is to improve the efficiency of the method of processing rare earth phosphate concentrate due to its simplicity and reduced consumption of reagents with a high degree of REE extraction from FRSQ.

The technical result of the invention is to achieve the degree of REE extraction from FRSC to 99% by reducing the flow of ammonia at the stage of neutralization of nitric-phosphoric acid solution, the flow of nitric acid and hydrogen peroxide to dissolve FRSC by 10%.

The proposed method eliminates the disadvantages of the method on the prototype, namely:

- no additional hardware is required for sedimentation and filtration of large volumes of suspensions of insoluble precipitate in nitric-phosphoric acid solution;

- insoluble residue from the stage of dissolution FRSC after washing from him soluble REE goes into the production cycle of obtaining complex fertilizers;

- insoluble residue from the stage of dissolution FRSC not served on stage obeshlorivanie, and therefore to produce a marketable salts crematorio sodium or calcium does not require additional purification stages;

for rinsing the insoluble residue does not require special equipment, it is provided for filtering the solution decomposition FRSC;

- no return (recycling) REE in the beginning of the production cycle FRSC, there's no flow of reactants to the deposition of an additional quantity of REE from nitrogen-phosphate solution and obtaining a solution of nitrate salts REE, which is about 10%of the total consumption of reagents.

This object is achieved in that the processing of phosphate of rare earth concentrate, isolated by neutralizing nitric-phosphoric acid solution obtained after dissection of Apatite nitric acid, includes the processing of rare earth phosphate concentrate nitric acid, separating the insoluble residue from the resulting nitrate-phosphate solution of rare earth elements and washing of the insoluble residue. While washing the insoluble residue is conducted with a solution of ammonium nitrate concentration of 40-70 wt.%, the flow rate of solution of ammonium nitrate when washing the insoluble residue maintained within the range of 2-5 wt.h. 1 wt.h. the insoluble residue. The washing solution combine with the target solution REE supplied to the extraction, the insoluble precipitate of return in the production of complex fertilizers, for the transport of insoluble sludge is used exhaust nitrogen-phosphate solution after the separation from it of rare earth phosphate concentrate.

At the same time as the leaching solution can be used a solution of ammonium nitrate, a conversion of calcium nitrate, isolated by crystallization from a solution of the decomposition of Apatite nitric acid, with a solution of ammonium carbonate.

Use for washing the insoluble precipitate nitrate solution s is one allows with regard to liquid-solid (hereinafter referred to W/T) (2÷5)/1 by weight to achieve up to a 95% degree of washing of the REE from the insoluble precipitate, and consequently to 99% degree of REE extraction from FRSQ.

The washing liquor (filtrate) is combined with the main solution (the filtrate) and then after adjusting the composition according to the content of vicariates is directed to extraction of REE by known methods.

According to the claimed method there is no need for additional equipment for preliminary sludge and filter large volumes of suspension of the insoluble residue nitrogen-phosphate solution. Washing the insoluble residue is carried out directly on the filter. That is, the recycle stream REE is eliminated, and accordingly eliminates the additional consumption of reagents for the precipitation of REE from the leaching solution and their subsequent dissolution.

The insoluble residue, representing silicon dioxide with impurities of iron compounds and titanium, is returned on receipt of complex fertilizers. At the same time as the transport fluid can be used nitrogen-phosphate solution after separation from it of rare earth concentrate. Transportation insoluble residue can be used part of the solution or the entire stream.

Due to the fact that the insoluble residue is not served at the stage of purification of the nitrogen-phosphate solution from fluorine, which is a necessary stage to obtain FRSC good quality, pollution salts of fluorine (crematoria NAT the Oia, potassium, calcium and others) is not observed and after washing these salts from water-soluble impurities these salts can be produced as commercial products.

The Association of the leaching solution with the main filtrate REE excludes return (recycling) REE in the beginning of the production cycle FRSC, that is, reduced consumption of reagents on the stage of neutralization (ammonia) nitrogen-phosphate solution, solution by dissolving FRSC (nitric acid and hydrogen peroxide) by about 10% compared to the prototype.

Ammonium nitrate, which is part of the leaching solution is a strong wycliffism component, allowing to increase the partition coefficients in extraction methods purification of nitrate-phosphate solutions REE from phosphates and other impurities.

Solutions of ammonium nitrate concentration of 40-70% by weight. are intermediate technological environments in the production of complex fertilisers produced by the decomposition of Apatite nitric acid, to obtain no additional cost.

Implementation of the proposed method in an industrial environment unlike the prototype will reduce raw material and energy resources and to obtain nitrogen-phosphate solution REE required quality for subsequent separation from him REE extraction method.

In tables 1, 2, 3 examples, illustrating the opportunity to obtain a solution of desired quality for extraction on the total content of rare earth elements in terms of oxides (hereinafter RSO), acidity and content of vicariates using solutions of ammonium nitrate for washing the insoluble precipitate remaining after the dissolution FRSC in nitric acid.

From the examples in table 1, it is seen that getting ready solution for extraction with the required values to the total content of RSO (not less than 65 g/l) acidity (70-90 g/l) and the contents of vicariates (ammonium nitrate - at least 600 g/l) is possible only if the insoluble precipitate from the stage of dissolution FRSC not washed, and the loss of RSO with apramycin sediment exceed 10% (example 1, table 1 11,3%). Washing the precipitate with acidified water leads to reduced losses to 2.4% when W/T=2:1, but the total content of RSA with the finished solution is reduced to 60 g/l, which is highly undesirable for the extraction cascade. Rinse when W/T=4:1 leads to a decrease in the amount of RT with the finished solution is reduced to 42 g/l, the processing of such solution extraction method will lead to large losses of RSO in the extraction step.

The examples in table 2 show that the use for washing the insoluble precipitate solutions of ammonium nitrate concentration of 40-70% at T/W = 2:1, when the losses RSO 2.4 percent; allows you to get complete solutions for extraction with the total content of RSO 70-80 g/l decrease in the nitrate content of shumilkin) is in the washing solution up to 20% leads to decrease in the content of the sum of RT in solution to an extreme value of 65 g/l

The examples in table 3 show that the use for washing the insoluble precipitate solutions of ammonium nitrate concentration of 57% at T/W below 2:1 leads to increased losses of RSO to 5%, which is also undesirable. When the ratio T/W is (2÷5)/1, losses are down to 1.1 to 2.5%, while the total content of RSO in the resulting solution is 59-76 g/l Increase in T/W with the flushing of sediment above 5:1 leads to a decrease in the content of the sum of RSO in the resulting solution below 55 g/L.

Examples

All of the examples shows how to obtain the solution of nitrate salts the amount of RT containing about 80 g/l of free nitric acid and about 600 g/l of ammonium nitrate from 128, 5 g FRSC with the total content of RSO of 22.2% and a humidity of 45%.

Table 1 provides data on the composition of the obtained solutions and the degree of extraction sums of RSO in solution, provided that the insoluble residue from the stage of dissolution FRSC not washed or flushed with water at a ratio of T/W, equal(2÷4):1.

Table 2 shows data on the composition of the obtained solutions and the degree of extraction sums of RSO in solution, provided that the insoluble residue from the stage of dissolution FRSC washed with solutions of ammonium nitrate concentration from 0 to 70% when the ratio T/W, equal to 2:1.

Table 3 shows data on the composition of the obtained solutions and the degree of izvlecheny the amount of RSO in the solution provided if the insoluble residue from the stage of dissolution FRSC washed with solutions of ammonium nitrate concentration of 57% and 70% when the ratio T/W, equal(0,5÷6):1.

Example 1 (Experiment 1, table 1).

for 125.8 g FRSC with the total content of RSO of 22.2% and a humidity of 45% is dissolved in 122,4 g 58% nitric acid in the presence of 10 g of 30% hydrogen peroxide solution. The obtained nitrogen-phosphate suspension is filtered. Get 211,8 g of the filtrate with the total content of RSO 11.6% and 45 g of sediment with the content of the retained liquid phase 60% and the total content of RSO of 7.3%. The precipitate is not washed. To the obtained filtrate add 181,2 g of ammonium nitrate and receive 391 g of the prepared solution for extraction with the total content of RSO 90,2 g/l of nitric acid of 80.6 g/l, ammonium nitrate 600 g/L. the Output amount of RSO in a ready solution is to 88.7%, and the loss amount RSO with apramycin sediment 11.3 per cent.

Example 2 (Experiment 2, table 1).

for 125.8 g FRSC with the total content of RSO of 22.2% and a humidity of 45% is dissolved in 142,6 g 58% nitric acid in the presence of 10 g of 30% hydrogen peroxide solution. The obtained nitrogen-phosphate suspension is filtered. The precipitate is washed with acidified water when W/T=2:1 and wash the filtrate is added to the main filtrate. Get was 322.3 g of the filtrate with the total content of RSO of 8.4%. To the total filtrate add 300 g of ammonium nitrate and obtain 620 g of the prepared solution for extraction with content the amount of RSO 60.1 g/l, nitric acid 79.1 g/l, ammonium nitrate 600 g/L. the Output amount of RSO in a ready solution is of 97.6%, and the loss amount RSO with the washed precipitate of 2,4%.

Example 3 (Experiment 4, table 2).

for 125.8 g FRSC with the total content of RSO of 22.2% and a humidity of 45% is dissolved in to 130.6 g 58%) of nitric acid in the presence of 10 g of 30% hydrogen peroxide solution. The obtained nitrogen-phosphate suspension is filtered. The precipitate is washed with a solution of ammonium nitrate 57% wt. when W/T=2:1 and wash the filtrate is added to the main filtrate. Get 310, 2 g of the filtrate with the total content of RSO of 8.7%. To the total filtrate add 192,9 g of ammonium nitrate and receive 501 g of the prepared solution for extraction with the total content of RSO 75,9 g/l of nitric acid of 80.9 g/l, ammonium nitrate 600 g/L. the Output amount of RSO in a ready solution is 97.5%, and the loss amount RSO with the washed precipitate of 2.5%.

Example 4 (Experiment 9, table 3).

for 125.8 g FRSC with the total content of RSO of 22.2% and a humidity of 45% is dissolved in 130,9 g 58% nitric acid in the presence of 10 g of 30% hydrogen peroxide solution. The obtained nitrogen-phosphate suspension is filtered. The precipitate is washed with a solution of ammonium nitrate 70% wt. when W/T=4:1 and wash the filtrate is added to the main filtrate. Get 400,8 g of the filtrate with the total content of RSO of 6.8%. To the total filtrate add 128,4 g of ammonium nitrate and receive 527 g of the prepared solution for extracti the content amount of RSO to 72.6 g/l, nitric acid 77,8 g/l, ammonium nitrate 600 g/L. the Output amount of RSO in a ready solution is to 98.6%, and the loss amount RSO with the washed precipitate of 1.4%.

1. A method of processing rare earth phosphate concentrate, isolated by neutralizing nitric-phosphoric acid solution obtained after dissection of Apatite nitric acid, including the processing of rare earth phosphate concentrate nitric acid, separating the insoluble residue from the resulting nitrate-phosphate solution of rare earth elements (REE), wash the insoluble residue and the extraction of rare earth elements from solution REE, characterized in that the washing of the insoluble residue is conducted with a solution of ammonium nitrate concentration of 40-70% by weight. with a flow rate of solution of ammonium nitrate 2-5 wt.h. 1 wt.h. the insoluble residue, the washing liquor is combined with a solution of REE supplied to the extraction, and the insoluble residue is directed to the production of complex fertilizers.

2. The method according to p. 1, wherein the solution of ammonium nitrate conversion are TETRANITRATE calcium selected from nitrogen-phosphate solution polythermal crystallization with ammonium carbonate.

3. The method according to p. 1, characterized in that for transportationstorage sludge use exhaust nitrogen-phosphate solution after the separation from it of rare earth phosphate concentrate.



 

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1 tbl, 1 ex

FIELD: chemistry.

SUBSTANCE: claimed is a method for the extraction of tungsten from scheelite. The introduction of an acid mixture, containing sulphuric acid and orthophosphoric acid, into a decomposition reactor, heating to 70-100°C and the addition of sheelite under control of a ratio of liquid and solid phases at the level of 3:1-8:1 l/kg are realised. Then, after 1-6 h of the reaction carried out are filtration and crystallisation of the obtained filtrate, which is compensated with sulphuric acid, consumed in the reaction for obtaining a crystal of phosphotungstic acid and a residual solution. After that, dissolution of the crystal of phosphotungstic acid in water is carried out with its conversion into a solution of ammonium tungstate, containing 200-300 g/k of WO3. The said solution is used for the preparation of ammonium paratungstate. The residual solution after compensation with orthophosphoric acid and water to the initial level is directed to scheelite leaching.

EFFECT: reduction of expenditures and reduction of tungsten loss.

4 cl, 7 dwg, 1 tbl, 9 ex

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