Method of recovering rare-earth elements from phosphogypsum

FIELD: rare-earth element technology.

SUBSTANCE: invention relates to technology of recovering rare-earth elements from phosphogypsum obtained from processing of apatite concentrate into mineral fertilizers. Phosphogypsum is treated with 22-30% sulfuric acid solution at liquids-to-solids ratio 1.8-2.2 to recover rare-earth elements and sodium into solution. Insoluble precipitate is separated and degree of oversaturation of solution regarding rare-earth elements is increased by means of providing sodium concentration 0.4-1.2 g/L, after which crystallization of rare-earth element concentrate is allowed to proceed and concentrate is then separated from mother liquor. Treatment duration is 20-30 min to prevent spontaneous crystallization of rare-earth element concentrate in solution before insoluble precipitate is separated. Content of sodium in solution is controlled by adding a sodium salt thereto, preferably sodium sulfate or sodium carbonate. Degree of recovery of rare-earth elements from phosphogypsum into concentrate achieves 71.4%.

EFFECT: increased degree of rare-earth element recovery and simplified procedure due to eliminated operation of dilution of recycle sulfuric acid solutions and shortened sulfuric acid treatment duration by a factor of 2-3.

2 cl, 1 tbl, 3 ex

 

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

The existing methods for extracting rare earth elements from phosphogypsum, providing for the processing of mineral acids with subsequent precipitation of the obtained solutions of phosphate or fluoride concentrates have not found industrial application. The reason for this is the difficulty of separation of fine-grained sediments on the basis of fluorides or phosphates of the lanthanides, the complexity and high cost of their further processing, and high reagent, energy and labor needed for the processing of large volumes of solutions with a low content of the target component. In addition, not solved the problem of disposal of solutions after separation of rare earth elements.

The method for extracting rare earth elements from phosphogypsum (see application NDP No. 272533, MKI5C 01 F 11/46, C 01 F 17/00, 1989), including the processing of phosphogypsum heated to 50°With sulfuric acid concentration of 10-20 wt.% in the quantitative ratio of the acid to the phosphogypsum 1:1-4, aging the mixture at an elevated temperature within 15-70 min, concentrating the resulting solution by evaporation to the content of sulfuric acid is more than 30 wt.% and accelerationratio solid phase, containing rare earth elements. The degree of extraction of rare earth elements in the solid phase is 10-25%.

The disadvantages of this method are the low degree of extraction of rare earth elements from phosphogypsum, the relative complexity of the method and its high energy consumption due to evaporation of large volumes of solutions.

Closest to the present invention is a method for extracting rare earth elements from phosphogypsum (see RF patent №2225892, IPC722 In 59/00, 3/08; 2004), including the leaching of phosphogypsum by sequential processing of multiple portions of phosphogypsum one solution of sulfuric acid with a concentration of 20-25 wt.% if F:T=2-3 with the extraction of rare earth elements and sodium in the leaching solution, separating the insoluble residue, increasing the degree of supersaturation of the solution of rare earth elements by introducing at a temperature of 20-80°With concentrated sulfuric acid to its content of not less than 30 wt.%, crystallization of the concentrate of rare earth elements from the supersaturated solution, the separation of the concentrate of rare earth elements from the mother liquor by filtration and subsequent processing of the concentrate solution of CA(NO3)2or CaCl2obtaining a concentrated solution of nitrates or chlorides of rare earth elements. Crystallization to which centrata rare earth elements, preferably in the presence of seed sulfates REE at W:T not more than 100 within of 0.4 to 3.0 hours The solution after separation of the concentrate of rare earth elements partially directed to the decomposition of Apatite concentrate, and partially after dilution with water to a concentration of sulfuric acid 20-25 wt.% used in circulation for leaching of phosphogypsum. The duration of the leaching of phosphogypsum is 60 minutes, the Degree of extraction of rare earth elements in the concentrate was 50.0-60,2%.

The known method is characterized by insufficient high degree of extraction of rare earth elements from phosphogypsum and the relative complexity of the method according to the reason of the increased number of operations, significant amounts of working capital sulfate solutions (1.2 m3and more than 1 t of phosphogypsum) and the duration of the leaching operation.

The technical result of the invention is to increase the degree of extraction of rare earth elements from phosphogypsum and to simplify the method due to the reduced number of operations, reduce the volume of circulating sulfate solutions and reduce the duration of the operation of the leaching of rare earth elements.

The technical result is achieved in that in the method for extracting rare earth elements from phosphogypsum, including his handling of a sulfuric acid solution with the extraction of rare earth elements and sodium in the solution, separating the insoluble residue, increasing the degree PE is asimenia solution of rare earth elements for the crystallization of the concentrate of rare earth elements, the separation of the concentrate from the mother liquor and recycling the concentrate according to the invention the processing of phosphogypsum are sulfuric acid solution with a concentration of 22-30 wt.% if F:T=1.8 to 2.2 and duration 20-30 min to exclude spontaneous crystallization of the concentrate of rare earth elements from the solution before the separation of the insoluble residue, and increasing the degree of supersaturation of the solution reached by ensuring that the content of sodium in a solution of 0.4 to 1.2 g/L.

The technical result is also achieved by the fact that the sodium content in the leaching solution regulate by introducing salts of sodium, mainly sulfate or sodium carbonate.

The essence of the claimed method consists in the following. In the leaching of rare earth elements from phosphogypsum (postopera) sulfate solutions average concentrations (22-30 wt.%) dissolution of hydrated phosphate of rare earth elements flows through the reaction:

where n≥1. The major part of the rare earth elements dissolved in 20-25 minutes.

Simultaneously with the dissolution of rare earth elements from phosphogypsum in the leaching solution pass the cations of sodium, which in sulfuric acid solutions to form a lanthanide double sulfate according to the reaction:

P is because the solubility of double sulfates of rare earth elements and sodium sulfate solutions average concentrations are low, then when the solution is supersaturated state they precipitate. Experimentally it was found that the solubility of the double sulphate is reduced with excess sodium concentration and high-concentration sulfuric acid.

Use for leaching of phosphogypsum solutions of sulfuric acid with a concentration of more than 30 wt.% leads to a sharp decrease in the extraction of rare earth elements in the leaching solution. The concentration of sulfuric acid below 22 wt.% impractical, as insufficient to ensure the necessary degree of crystallization of the concentrate of rare earth elements from the supersaturated solution.

The increasing ratio of W:T over 2.2 slightly increases the extraction of rare earth elements in the leaching solution, but leads to a decrease in the degree of crystallization of the concentrate of rare earth elements from the supersaturated solution and the increase in the volume of solutions, which makes their further processing and use in the production of wet-process phosphoric acid. The decrease of the ratio W:T below 1.8 leads to a decrease in the extraction of rare earth elements in the leaching solution.

The processing of phosphogypsum with a solution of sulfuric acid for 20-30 minutes due to the need to avoid spontaneous crystallization of rare earth concentrate elementalis solution before the separation of the insoluble residue, because otherwise, the part is passed into a solution of rare earth elements will go to waste in the insoluble residue. At the time leaching less than 20 min reduced the extraction of rare earth elements in the solution, so as not time to dissolve hydrated lanthanide phosphates, in which the lanthanide is present in the phosphogypsum. At the time of leaching over 30 min extraction of rare earth elements in the solution decreases due to the onset of crystallization of the concentrate of rare earth elements from the supersaturated solution before the separation of the solid residue of phosphogypsum and contact leached phosphogypsum.

Increasing the degree of supersaturation of the solution, the leaching of rare earth elements during processing of phosphogypsum sulfuric acid solution within a specified period of time allows the controlled crystallization of the concentrate of rare earth elements from the leaching solution. The maintenance of sodium in the leaching solution in the range 0.4-1.2 g/l prevents deposition of double sulfates of rare earth elements and sodium in the leaching process and to provide sufficient speed and completeness of crystallization of these double sulphates after separation of the leaching solution from the insoluble residue.

When the concentration of sodium in the races the thief leaching more than 1.2 g/l crystallization of a double sulfates of rare earth elements and sodium occurs during the leaching operation. While the lanthanides again concentrated in the insoluble residue of phosphogypsum, but not in the form of phosphates, in the form of a double sulfate with sodium. This reduces the extraction of rare earth elements in the leaching solution.

When the concentration of sodium in the solution leaching below 0.4 g/l in the processing of phosphogypsum with a solution of sulfuric acid decreases the extraction of rare earth elements in the concentrate due to the lack of sodium in the solution for the formation of double sulfates of rare earth elements with sodium and vysalivaniya remaining in the solution by an excess of sodium cations.

Sodium cations can be introduced into the leaching solution in the form of sulphate, carbonate, or sodium chloride, however, are preferred sulfate or sodium carbonate from the point of view of preserving the anionic composition of the leaching solution.

The combination of the above features is necessary and sufficient to achieve the technical result of the invention to increase the degree of extraction of rare earth elements from phosphogypsum, as well as in reducing the number of operations, decrease turnaround sulfate solutions and reducing the duration of leaching of rare earth elements. The result is improved efficiency of the method in its simplification and reduction of energy intensity and volume using the constituent equipment.

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

Example 1. 100 g of waste phosphogypsum containing 0,41 wt.% ΣLn2About3and 0.05 wt.% Na, treated with stirring with a solution of N2SO4with a concentration of 26 wt.% if F:T=2 for 25 minutes At this concentration ΣLn2O3and Na in the leaching solution were respectively of 1.97 and 0.3 g/L. the resulting solution is separated from the insoluble residue of phosphogypsum add 1.54 g/l Na2SO4(the content of sodium in a solution of 0.8 g/l) and incubated for 2 hours. Crystallized precipitate concentrate rare earth elements separated by filtration from the mother liquor. X-ray phase analysis showed that the concentrate consists of double sulfates of rare earth elements and sodium mixed with calcium sulphate. The chemical composition of the concentrate, wt.%: ΣLn2O329,1; SO42-54,4; CaO 8,00; P2O50,3; Fe2About30,37; Al2O30.08 and SiO20,47. The degree of extraction of rare earth elements in the concentrate was 70.5%. The obtained concentrate was treated for 2 h with a solution of nitrate of calcium taken with an excess of 5% based on the ion binding SO42-in the calcium sulfate in W:T=5, while in the nitric acid solution is passed 95,5% ΣLn2About3.

Specific Yes the basic technological parameters of the process and the results obtained in Example 1, and Examples 2-3 are shown in the Table.

Example 2. The process is conducted in accordance with the conditions of Example 1. The difference lies in the fact that a portion of waste phosphogypsum is treated with a solution of N2SO4with a concentration of 22 wt.% if F:T=1.8 V for 30 minutes In the leaching solution after separation from the insoluble residue of phosphogypsum add 2,07 g/l Na2CO3(the content of sodium in a solution of 1.2 g/l). The degree of extraction of rare earth elements in the concentrate was 69.4%.

Example 3. The process is conducted in accordance with the conditions of Example 1. The difference lies in the fact that a portion of waste phosphogypsum is treated with a solution of N2SO4with a concentration of 30 wt.% if F:T=2.2 V for 20 min In the leaching solution after separation from the insoluble residue of phosphogypsum added 0.31 g/l Na2SO4(the content of sodium in a solution of 0.4 g/l). The degree of extraction of rare earth elements in the concentrate amounted to 71.4 per cent.

From the analysis of the above Examples and the Table shows that the proposed method allows to increase the degree of extraction of rare earth elements from phosphogypsum in concentrate to 71.4%. The method is simpler due to the exclusion of the operation of the dilution of the circulating sulfuric acid solution and accordingly reduce the volume of recycled sulfuric acid solutions, as well as reduce p is abolitionniste leaching of rare earth elements in 2-3 times.

Table
Example No.Technological products, theThe duration of the acid treatment, minThe content (solid phase wt.%, solution g/l)Removing ΣLn2O3phosphogypsum, %
ΣLn2O3Na
1Solution leaching 26% H2SO4W:T=2,0251,970,8077,2
Concentrate lanthanidesof 31.44,270,5
The mother liquor0,170,556,7
2The leaching solution 22% H2SO4W:T=1,8302,581,2091,0
Concentrate lanthanides30,64.09 to69,4
The mother liquor0,610,9221,6
3 The leaching solution 30% H2SO4W:T=2,2201,970,485,0
Concentrate lanthanides32,64,3671,4
The mother liquor0,320,1713,6

1. The method for extracting rare earth elements from phosphogypsum, including his handling of a sulfuric acid solution with the extraction of rare earth elements and sodium in the solution, separating the insoluble residue, increasing the degree of supersaturation of the solution of rare earth elements for the crystallization of the concentrate of rare earth elements, the separation of the concentrate from the mother liquor and recycling the concentrate, characterized in that the processing of phosphogypsum are sulfuric acid solution with a concentration of 22-30 wt.% if F:T=1.8 to 2.2 and duration 20-30 min to exclude spontaneous crystallization of the concentrate of rare earth elements from the solution before the separation of the insoluble residue, increasing the degree of supersaturation of the solution reached by ensuring that the content of sodium in a solution of 0.4 to 1.2 g/L.

2. The method according to claim 1, characterized in that the sodium content of the solution is regulated by introducing salts of sodium, mainly self the one or sodium carbonate.



 

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EFFECT: the invention ensures a decreased consumption of reactants, increased extraction of cobalt, nickel, manganese and copper.

2 cl, 1 dwg, 7 tbl

FIELD: metallurgy; complex processing of copper concentrate.

SUBSTANCE: proposed method includes sulphatizing roasting of starting concentrate and leaching-out of cinder at separation of metals; sulphatizing roasting of starting copper concentrate is performed in air at temperature of 500-600°C continued for 980-180 min; cinder thus obtained is leached-out with sulfuric acid solution or water at separation of cake and filtrate; copper is extracted from filtrate by electrolysis. Dried cake is blended with oxidizing agent and chlorides of alkaline and alkaline-earth metals and is subjected to heat treatment at temperature of 450-550°C for obtaining the cake which is leached-out by hydrochloric acid; noble metals are separated from filtrate by sorption method.

EFFECT: enhanced efficiency of extraction of metals; reduced power requirements; enhanced ecological safety.

9 cl, 1 dwg, 1 tbl, 3 ex

FIELD: hydrometallurgy, in particular treatment of metal containing sulfide ores and concentrates.

SUBSTANCE: reaction is carried out by mixing of metal containing sulfide ores and concentrates, wherein said metal is selected from group comprising of iron, copper, zinc, nickel, cobalt, and manganese, with concentrated sulfuric acid at temperature of 300-400°C in presence of oxygen to provide solid metal sulfate and gaseous reaction product, essentially sulfur trioxide. Solid metal sulfate is extracted with diluted (5 %-35 %) sulfuric acid solution to recover metal components therefrom and to form metal containing solution. Formed sulfur trioxide is compounded with metal containing solution to deposit metal sulfate from said solution and to obtain sulfuric acid with concentration in solution of about 35-50 %.

EFFECT: method for production of high purity metal sulfates without using of additional reagent amount.

8 cl, 11 ex

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

The invention relates to the processing of uranium ores

The invention relates to the processing orangutango raw materials

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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