The method for extracting rare earth elements from phosphogypsum

 

(57) Abstract:

The invention relates to the technology of extraction of rare earth elements (REE) from phosphogypsum obtained by sulphuric acid processing of Apatite concentrate on mineral fertilizers. The invention consists in the fact that consistently lead leaching in some portions of phosphogypsum one solution of sulfuric acid with a concentration of 20-25% at W:T=2-3 with translation REE into solution. From the resulting solution leaching is performed crystallization of REE concentrate at a temperature of 20-80C introduction in a solution of concentrated sulfuric acid to its content in the solution is not less than 30%. Crystallization of REE concentrate preferably in the presence of seed sulfates REE at W:T not more than 100 for 0.5 to 3.0 hours, the Obtained concentrate was separated by filtration and treated with a solution of Ca(NO3)2or CaCl2obtaining a concentrated solution of nitrates or chlorides of rare-earth elements. The solution after separation of the REE concentrate used in the leaching of phosphogypsum. Achievable technical result is to increase the efficiency of the method of extracting rare earth elements from phosphogypsum by reducing the energy intensity of the process and pausewang nitrate or chloride solutions, suitable for subsequent processing and use. 3 C.p. f-crystals, 1 table.

The invention relates to the technology of extraction of rare earth elements (REE) from phosphogypsum obtained by sulphuric acid processing of Apatite concentrate on mineral fertilizers.

The existing methods for extracting rare earth elements from phosphogypsum provide for his handling of acids or salt solutions with the subsequent deposition of the obtained solutions of phosphate or fluoride concentrate. These methods, however, have not found application in industry due to their high energy consumption and a significant consumption of reagents in the processing of large volumes of solutions with a low content of the target component, and also because of the difficulty of separation of fine-grained sediments on the basis of fluorides or phosphates REE, complexity and cost of their further processing. In addition, there remains the unresolved issue of the disposal of solutions after separation of the REE.

The method for extracting rare earth elements from phosphogypsum (see Lokshin E. P., Vershoks A. C., vershkov Y. A. Problems of the separation of rare earth metals in the acid treatment of the Khibiny Apatite concentrate // Metals. - 2001. No. 1. S. 42-51), vklycheniem concentration of sulfuric acid in the leaching of subsequent portions to limit values, equal to 20-22%. Recovery of REE from the obtained solutions leaching is performed by ion flotation using as the collector of a mixture of mono - and dialkylphosphorous acids with long alkyl radical 7-14 atoms, then produce isotoxicity regeneration of the collector to obtain solutions REE containing 30 g/l, suitable for extraction separation. The average recovery of REE into solution leaching does not exceed 43,9%.

The main disadvantage of this method is the relatively low recovery of REE into solution leaching and low Ln2ABOUT3in the final solution. In addition, the implementation of ion flotation and regeneration of the collector require sophisticated equipment and expensive reagents.

Closest to the proposed invention is a method for extracting rare earth elements from phosphogypsum (see application NDP No. 272533, MKI4C 01 F 17/00, 1989), including the leaching of phosphogypsum by sequential processing of multiple portions of phosphogypsum one solution of sulfuric acid with a concentration of 10-20% at W:T=1-4 and elevated temperature during 15-70 min with translation REE in solution, crystallization of REE concentrate by evaporation of rest is m and its subsequent processing.

The known method is characterized by increased energy consumption due to evaporation of large volumes of solutions. In addition, the resulting concentrates are characterized by low (10-25%) of the REE contents.

The present invention is directed to solving the problem of improving the efficiency of extracting rare earth elements from phosphogypsum by reducing the energy intensity of the process and production of concentrates with a higher content of REE. The invention is also aimed at solving the problem of obtaining REE in the most suitable for subsequent processing and use of the form.

The problem is solved in that in the method for extracting rare earth elements from phosphogypsum, including leaching of phosphogypsum by sequential processing of multiple portions of phosphogypsum one solution of sulfuric acid with the translation of REE into solution, crystallization of REE concentrate from the resulting solution leaching, separation of the concentrate by filtration and subsequent processing, according to the invention the leaching of phosphogypsum are sulfuric acid solution with a concentration of 20-25% at W:T=2-3, and crystallization is carried out at a temperature of 20-80C introduction to the leaching solution of concentrated sulfuric acid until the soda is ncentrate carried out in the presence of seed sulfates REE in W:T is not more than 100 for 0.5 to 3.0 hours

The problem is solved and the fact that the processing of lead concentrate by treatment with a solution of CA(NO3)2or CaCl2obtaining a concentrated solution of nitrates or chlorides of rare-earth elements.

The task also contributes to the fact that the solution after separation of the REE concentrate used in the leaching of phosphogypsum.

Use in the leaching step of phosphogypsum solutions with sulfuric acid concentration above 25% leads to a decrease of REE extraction in the leaching solution, and reducing the concentration below 20% is impractical due to the increased consumption of acid at the stage of crystallization of REE concentrate.

The increasing ratio of W:T more than 3 slightly increases the extraction of lanthanides in the leaching solution, but leads to decreasing concentrations of REE and increase solutions that hinders their further processing and use in the production of EPA. Reduction W:T less than 2 results in trudnoperevarivaema pulp.

Lowering the concentration of H2SO4in the solution is less than 30% at the stage of crystallization of REE concentrate increases the solubility of REE and thereby decreases the degree of their kind who W:T not more than 100 intensifies the process of sediment, however, increasing the mixing time of sediment over 3 h does not lead to a noticeable increase in the content of REE concentrate.

In the processing of REE concentrate solution of CA(NO3)2or l2get a concentrated solution of nitrates or chlorides of rare-earth elements, suitable for the separation of REE known methods, and the resulting gypsum is sent to the dump.

The essence of the proposed method can be explained by the following examples.

Example 1. Consistently handle one solution 20% H2SO4three servings of phosphogypsum containing 0.45% Ln2ABOUT3if F:T=3 and time leaching 1 o'clock In the resulting solution leaching enter H2SO4with a concentration of 93.5% to hold her in a solution of 40% and maintained at a temperature of 80 C and stirring for 12 hours Crystallized precipitate, representing the REE concentrate is separated by filtration. The resulting concentrate contains 30,1% Ln2ABOUT3. The accumulation of REE concentrate is directed to the processing of obtaining a concentrated solution of nitrates of rare-earth elements.

Specific information on the process parameters and the results obtained in example 1 and examples 2-4 are shown in table.

Example 3. The process is conducted under the conditions of Example 2, but are the leaching of the two portions of phosphogypsum mother liquor after separation of the precipitate from example 2, diluted to a content of H2SO425%, W:T=2. The crystallization is carried out in the presence of sulfate seed concentrate at W:T=74, the contents of H2SO4in a solution of 35% and a temperature of 20 C for 3 h the resulting concentrate contains 40,2% Ln2ABOUT3. Two portions of REE concentrate is treated sequentially with a solution of CaCl2if F:T=10 and the flow CaCl2105% of stoichiometry. The obtained concentrated solution of chloride REE sent for recycling known methods.

Example 4. The process is conducted under the conditions of example 3, but the crystallization is carried out in the presence of sulfate seed concentrate obtained in example 3, when W:T=100, the content of H2SO4in a solution of 30% and a temperature of 20C for 2 hours the resulting concentrate contains 44.7% Ln2ABOUT3. Two is>)2105% of stoichiometry. The obtained concentrated solution of nitrate REE sent for recycling known methods.

Thus, from the above examples that the proposed method can improve the efficiency of the process of extracting rare earth elements from phosphogypsum by reducing the energy intensity of the process and production of concentrates with high (30,1 is 44.7%) content of REE. In addition, the proposed method may receive REE in the form of concentrated nitrate or chloride solutions, suitable for subsequent processing and use.

1. The method for extracting rare earth elements from phosphogypsum, including leaching of phosphogypsum by sequential processing of multiple portions of phosphogypsum one solution of sulfuric acid with the translation of rare earth elements (REE) in the solution, crystallization of REE concentrate from the resulting solution leaching, separation of the concentrate by filtration and further processing, characterized in that the leaching of phosphogypsum are sulfuric acid solution with a concentration of 20-25% at W:T=2-3, and crystallization is carried out at a temperature of 20-80C introduction to the leaching solution concentrated lisalu REE concentrate is carried out in the presence of seed sulfates REE in W:T is not more than 100 for 0.5 to 3.0 hours

3. The method according to p. 1 or 2, characterized in that the processing of lead concentrate by treatment with a solution of CA(NO3)2or CaCl2obtaining a concentrated solution of nitrates or chlorides of rare-earth elements.

4. The method according to any of paragraphs.1-3, characterized in that the solution after separation of the REE concentrate used in the leaching of phosphogypsum.

 

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FIELD: hydrometallurgy of non-iron, rare and noble metals.

SUBSTANCE: invention relates to reprocessing of metal sulfide-containing ores, products and waste of ore concentrating and metallurgy industry. Method includes leaching in sulfuric acid solution with concentration of 1.8-35 g/dm3 at 0-1500C in presence of iron(III) ions with concentration more than 1 g/dm3 and iron regeneration using element compounds having built-in voltage when transition from highest valence to lowest one higher the same of iron. Compounds are added into solution when increasing iron(II) ion concentration. Method is useful in leaching by bawl, percolation, heap, and underground processes, as well as in metal recovering into solution, development of rare and noble metals, impregnated in metal sulfides. Invention affords the ability to reduce power requirement, increase effectiveness of equipment utilization, and decrease reagent consumption.

EFFECT: high degree sulfide decomposition with increased metal recovery and reduced leaching time.

8 cl, 3 ex

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