Method for recovering rare earth in tungsten slag

Abstract

The invention provides a method for recovering rare earth in tungsten slag, and relates to the technical field of metallurgy. The rare earth recovery method provided by the invention comprises the following steps: (1) mixing tungsten slag with a decomposition aid, then mixing with concentrated sulfuric acid, calcining at low temperature, adding water, stirring, leaching, and carrying out solid-liquid separation to obtain a rare earth-containing leachate and tungsten-containing solid slag; (2) alkali is added into the rare earth-containing leachate to adjust the rare earth-containing leachate to proper acidity for iron removal, and rare earth-containing iron removal liquid and iron slag are obtained after filtration; and (3) the iron removal liquid containing the rare earth flows through an adsorption column filled with extraction resin for column adsorption, a resin column loaded with the rare earth and adsorption tail liquid are obtained, and ammonia soap or sodium soap is adopted for treatment before the extraction resin is adsorbed. And (4) desorbing the resin column loaded with the rare earth by using acid to obtain a high-concentration rare earth desorption solution which can be directly used for full separation of the rare earth in downstream rare earth separation enterprises. The sulfuric acid curing technology is adopted, the decomposition efficiency of the tungsten slag is enhanced, the rare earth leaching rate is larger than 95%, and the rare earth yield in the whole process is larger than 92%; the extraction resin adsorption separation mode is adopted, one-step separation of rare earth, iron, calcium, zinc, copper and the like is achieved, the enrichment process is simple, reagent consumption is low, and cost is low.

Description

Technical Field

[0001] The invention belongs to the technical field of metallurgy, and in particular relates to a method for recovering rare earth from tungsten slag. Background Art

[0002] my country is a major tungsten producer. Every year, the production of APT (ammonium paratungstate) using tungsten concentrate as raw material produces more than 200,000 tons of tungsten slag. At present, the inventory of tungsten slag in enterprises has reached more than 1 million tons. Realizing the "reduction, resource utilization, and harmlessness" of tungsten slag and opening up the "exit of tungsten slag" has always been a severe challenge facing the tungsten industry. The rare earth content in black tungsten slag is about 0.5-2%, which has a high recovery value.

[0003] For tungsten slag, researchers have conducted a series of recycling studies. Chinese patent CN202011225346.3 discloses a modified extraction method for rare earth elements in a scheelite-sintered red mud system. Through sintering pretreatment, NHCO joint activation, high-temperature reduction, product separation and collection, etc., mixed rare earth oxides are obtained. The purity of the mixed rare earth alloy in the alloy product is higher than 99%. However, the invention uses high-temperature reduction, and the energy consumption of the whole process is high, and it has not been industrialized. The National Tungsten and Rare Earth Product Quality Inspection and Testing Center cooperated with Dayu Donghong and other companies to develop a research and development project of "New Environmentally Friendly Leaching Agent for Efficient Extraction of Mineral Phase Rare Earths in Tungsten Slag (Tailings)", achieving a rare earth leaching rate of more than 70%. At present, the project is still in the pilot stage and has not been industrialized.

[0004] Tungsten slag was listed in the "National Hazardous Waste List" in 2016, which greatly increased the difficulty of disposal for enterprises and led to high disposal costs. Therefore, this technology has developed a method for the disposal of tungsten slag and achieved efficient recovery of rare earths. Summary of the invention

[0005] The purpose of the present invention is to provide a method for recovering rare earths in tungsten slag, which realizes efficient recovery of rare earths in tungsten slag acid leaching solution through low-temperature ripening leaching and extraction chromatography separation and recovery, and the recovery rate of rare earths is greater than 98%.

[0006] In order to achieve the purpose of the present invention, the present invention provides the following technical solutions:

[0007] A method for recovering rare earth from tungsten slag comprises the following steps:

[0008] Mix the black tungsten slag with concentrated sulfuric acid, heat and mature for 2 hours; add water to the matured material and stir to leach, and obtain rare earth-containing leachate and tungsten-containing solid slag after solid-liquid separation;

[0009] The rare earth-containing leaching solution is added with alkali to adjust the acidity to a suitable level for iron removal, and filtered to obtain a rare earth-containing iron removal solution and iron slag;

[0010] The rare earth iron removal liquid is passed through an adsorption column filled with leaching resin to perform column adsorption to obtain a rare earth loaded resin column and adsorption tail liquid;

[0011] The resin column loaded with rare earth is desorbed by acid to obtain a high-concentration rare earth-enriched liquid; the rare earth content in the rare earth-enriched liquid is greater than 200g / L and can be directly applied to the rare earth separation process.

[0012] Preferably, the black tungsten slag is slag produced by alkali decomposition of black tungsten ore or black tungsten mixed ore; the rare earth content in the slag is 0.1-2%.

[0013] Preferably, the concentrated sulfuric acid is commercially available concentrated sulfuric acid, and the molar concentration of sulfuric acid is 86% to 98%.

[0014] Preferably, the weight ratio of the black tungsten slag to concentrated sulfuric acid is 100:1 to 100:50.

[0015] Preferably, the aging temperature is room temperature to 250° C.; and the aging time is 0.5 to 3 hours.

[0016] Preferably, in the process of adding water and stirring for leaching, the weight ratio of water to the cooked material is 5:1 to 1:1; and the leaching time is 0.5 to 3 hours.

[0017] Preferably, the pH value of the rare earth-containing leaching solution is controlled to be 2-4 during the process of adding alkali to adjust the acidity and removing iron.

[0018] Preferably, the alkali may be a mixed alkali of one or more of sodium hydroxide, calcium hydroxide, magnesium hydroxide, magnesium oxide, and calcium oxide in any proportion.

[0019] Preferably, the leaching resin is prepared by mixing P507 extractant and CA-12 extractant, and then cross-linking and polymerizing with styrene and divinylbenzene to form a macroporous leaching resin.

[0020] Preferably, the volume ratio of the P507 extractant to the CA-12 extractant is 50:50 to 90:10, and a mixed extractant is obtained after mixing.

[0021] Preferably, the volume ratio of the mixed extractant to (styrene, divinylbenzene) is 10:90 to 50:50.

[0022] Preferably, the leaching resin is subjected to saponification treatment by passing ammonia water or an aqueous solution of sodium hydroxide through the resin before use; the saponification degree is controlled to be 30% to 100%.

[0023] Preferably, the rare earth-containing iron removal liquid flows through an adsorption column filled with leaching resin to perform column adsorption to obtain a rare earth-loaded resin column and adsorption tail liquid.

[0024] Preferably, when the rare earth content in the adsorption tail liquid is higher than 0.001 g / L, the feeding of the rare earth-containing iron removal liquid is stopped.

[0025] Preferably, in the acid desorption process, the acid is hydrochloric acid, sulfuric acid, nitric acid or a mixed acid of the three in any proportion.

[0026] Preferably, the acidity is 1-6 mol / L; when the rare earth content in the effluent is lower than 0.1 g / L, the acid addition is stopped and the desorption process ends.

[0027] The invention provides a method for recovering rare earth in tungsten slag, which adopts low-temperature ripening leaching and extraction chromatography separation recovery technology to achieve efficient enrichment of rare earth in tungsten slag, with simple process, less reagent consumption and low cost. DETAILED DESCRIPTION

[0028] The present invention provides a method for recovering rare earth from tungsten slag, comprising the following steps:

[0029] Mix the black tungsten slag with concentrated sulfuric acid, heat and mature for 2 hours; add water to the matured material and stir to leach, and obtain rare earth-containing leachate and tungsten-containing solid slag after solid-liquid separation;

[0030] The rare earth-containing leaching solution is added with alkali to adjust the acidity to a suitable level for iron removal, and filtered to obtain a rare earth-containing iron removal solution and iron slag;

[0031] The rare earth iron removal liquid is passed through an adsorption column filled with leaching resin to perform column adsorption to obtain a rare earth loaded resin column and adsorption tail liquid;

[0032] The resin column loaded with rare earth is desorbed by acid to obtain a high-concentration rare earth-enriched liquid; the rare earth content in the rare earth-enriched liquid can be greater than 200g / L and can be directly applied to the rare earth separation process.

[0033] In the present invention, unless otherwise specified, all raw materials are preferably commercially available products well known to those skilled in the art.

[0034] The present invention mixes black tungsten slag with concentrated sulfuric acid, heats and matures for 2 hours; adds water to the matured material, stirs and leaches, and obtains rare earth-containing leachate and tungsten-containing solid slag after solid-liquid separation. In the present invention, the black tungsten slag is derived from the slag after alkali decomposition of wolframite or black and white tungsten mixed ore; more preferably, it is the slag after alkali decomposition of wolframite; the rare earth content in the slag is 0.1-2%; preferably 0.02-1.5%, and more preferably 0.3-1.0%.

[0035] In the present invention, the concentrated sulfuric acid is commercially available concentrated sulfuric acid, and the molar concentration of sulfuric acid is 86% to 98%, preferably 90 to 98%, and more preferably 94 to 96%. The weight ratio of the black tungsten slag to the concentrated sulfuric acid is 100:1 to 100:50, preferably 100:5 to 100:40, and more preferably 100:10 to 100:30.

[0036] In the present invention, the aging temperature is room temperature to 250°C, preferably 100 to 250°C, more preferably 200 to 250°C; the aging time is 0.5 to 3 hours, preferably 1 to 2.5 hours, more preferably 1 to 2 hours.

[0037] In the present invention, during the water-adding, stirring and leaching process, the weight ratio of water to the cooked material is 5:1 to 1:1, preferably 5:1 to 2:1, and more preferably 5:1 to 4:1; the leaching time is 0.5 to 3 hours, preferably 1 to 2.5 hours, and more preferably 1 to 2 hours.

[0038] In the present invention, the rare earth leachate is added with alkali to adjust the acidity and the pH value of the leachate is controlled to be 2 to 4, preferably 2 to 3.5, and more preferably 2.5 to 3.5 during the iron removal process. The alkali can be a mixed alkali of one or more of sodium hydroxide, calcium hydroxide, magnesium hydroxide, magnesium oxide, and calcium oxide in any proportion, preferably sodium hydroxide, calcium hydroxide, and calcium oxide, and more preferably sodium hydroxide and calcium hydroxide.

[0039] In the present invention, the leaching resin is prepared by mixing P507 extractant and CA-12 extractant and then cross-linking and polymerizing with styrene and divinylbenzene to form a macroporous leaching resin. The volume ratio of the P507 extractant and the CA-12 extractant is 50:50 to 90:10. After mixing, the mixed extractant is preferably 60:40 to 80:20, and more preferably 65:35 to 85:15. The volume ratio of the mixed extractant to (styrene and divinylbenzene) is 10:90 to 50:50, preferably 20:80 to 40:60, and more preferably 25:75 to 35:65.

[0040] In the present invention, the leaching resin is subjected to saponification treatment by passing ammonia water or an aqueous solution of sodium hydroxide through the resin before use; the saponification degree is controlled to be 30% to 100%, preferably 40% to 95%, and more preferably 50% to 90%.

[0041] In the present invention, the rare earth iron removal liquid flows through an adsorption column filled with leaching resin to perform column adsorption to obtain a rare earth loaded resin column and adsorption tail liquid. When the rare earth content in the adsorption tail liquid is higher than 0.001 g / L, the rare earth iron removal liquid is stopped.

[0042] In the present invention, the desorption acid is hydrochloric acid, sulfuric acid, nitric acid or a mixed acid of the three in any proportion, preferably sulfuric acid and hydrochloric acid, more preferably sulfuric acid.

[0043] In the present invention, the acidity (in terms of H + The content of rare earth in the effluent is lower than 0.1 g / L, the acid is added and the desorption process is ended.

[0044] In the present invention, the solid-liquid separation method is preferably filtration, suction filtration or centrifugation.

[0045] In order to further illustrate the present invention, the method for recovering rare earth from tungsten slag provided by the present invention is described in detail below in conjunction with embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0046] Example 1

[0047] 1000g of black tungsten slag (the rare earth content in the slag is 1.56% in terms of REO) was mixed evenly with 100ml of concentrated sulfuric acid (concentration 96%), and heated to 250 degrees for aging for 2 hours to obtain a slaked material; 5000ml of water was added to the slaked material and stirred for 2 hours for leaching, and 4625ml of rare earth-containing leaching solution ([REO] = 3.2474g / L, [H + ]=0.2334mol / L) and tungsten-containing solid slag, and the rare earth leaching rate was calculated to be 96.28%; 80.55 grams of solid sodium hydroxide were added to the rare earth leaching solution under stirring, and the pH value of the leaching solution was adjusted to 3.0. After filtering and removing the solid slag, 4510 ml of rare earth-containing iron removal liquid ([REO]=3.1828g / L) was obtained; the rare earth-containing iron removal liquid was passed through an adsorption column equipped with 200g of leaching resin (volume ratio P507:CA-12= 50:50; mixed extractant in a volume ratio of: styrene and divinylbenzene = 50:50) (the resin is saponified with ammonia water, and the saponification degree is 80%), and column adsorption is performed to obtain a loaded rare earth resin column and an adsorption tail liquid ([REO] <1 mg / L); 75 ml of dilute hydrochloric acid ([HCl] = 5.0 mol / L) is added to the loaded rare earth resin column for desorption to obtain 70 mL of desorption liquid ([REO] = 205 g / L), and the rare earth yield of the whole process is 92.02%.

[0048] Example 2

[0049] 1000g of black tungsten slag (the rare earth content in the slag is 0.15% in terms of REO) was mixed evenly with 50ml of concentrated sulfuric acid (concentration 98%), and then aged at room temperature for 2 hours to obtain a mature material; 5000ml of water was added to the mature material and stirred for 2 hours for leaching, and 4854ml of rare earth-containing leaching solution ([REO] = 0.2938g / L, [H + ]=0.0334mol / L) and tungsten-containing solid slag, and the rare earth leaching rate was calculated to be 95.08%; 10 grams of solid sodium hydroxide was added to the rare earth leaching solution under stirring, and the pH value of the leaching solution was adjusted to 3.5. After filtering and removing the solid slag, 4825ml of rare earth-containing iron removal liquid ([REO]=0.2896g / L) was obtained; the above rare earth-containing iron removal liquid was passed through an adsorption column filled with 200g of leaching resin for adsorption (in the leaching resin, the volume ratio of P507:CA-12 =90:10; volume ratio of mixed extractant: styrene, divinylbenzene = 10:90) (the resin is saponified with ammonia water, and the saponification degree is 30%), and column adsorption is performed to obtain a loaded rare earth resin column and an adsorption tail liquid ([RE] <1mg / L); 100ml of dilute sulfuric acid ([H2SO4] = 2.0mol / L) is added to the loaded rare earth resin column for desorption to obtain 96mL of desorption liquid ([REO] = 14.52g / L), and the rare earth yield of the whole process is 92.93%.

[0050] Example 3

[0051] 1000g of black tungsten slag (the rare earth content in the slag is 1.98%) was mixed with 250ml of concentrated sulfuric acid (concentration 96%), heated to 250 degrees and aged for 2 hours to obtain a mature material; 4000ml of water was added to the mature material and stirred for 2 hours for leaching, and 3855ml of rare earth-containing leaching solution ([RE] = 4.904g / L, [H + ]=0.7293mol / L) and solid slag containing tungsten, and the rare earth leaching rate was calculated to be 95.48%; 176g of solid calcium oxide was added to the rare earth leaching solution under stirring, and the pH value of the leaching solution was adjusted to 2.0. After filtering to remove the solid slag, 3822ml of rare earth-containing iron removal liquid ([RE]=4.833g / L) was obtained; the above rare earth-containing iron removal liquid was passed through an adsorption column filled with 200g of leaching resin for adsorption (in the leaching resin, the volume ratio of P507:CA-12= 75:25; volume ratio of mixed extractant: styrene, divinylbenzene = 50:50) (the resin is saponified with ammonia water, and the saponification degree is 80%), and column adsorption is performed to obtain a loaded rare earth resin column and an adsorption tail liquid ([RE] <1 mg / L); 100 ml of nitric acid ([HNO3] = 4.0 mol / L) is added to the loaded rare earth resin column for desorption to obtain 91 mL of desorption liquid ([REO] = 200.89 g / L), and the rare earth yield of the whole process is 92.33%.

[0052] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for recovering rare earth from tungsten slag, characterized in that: The following steps are involved: (1) Mix the black tungsten slag with concentrated sulfuric acid and heat and mature for 2 hours; add water to the matured material and stir to leach, and obtain rare earth-containing leaching liquid and tungsten-containing solid slag after solid-liquid separation; (2) Add alkali to the rare earth-containing leaching liquid to adjust to a suitable acidity for iron removal, and obtain rare earth-containing iron removal liquid and iron slag after filtration; (3) Pass the rare earth-containing iron removal liquid through an adsorption column loaded with leaching resin for column adsorption to obtain a rare earth-loaded resin column and adsorption tail liquid. The leaching resin is prepared by mixing P507 extractant with CA-12 and polymerizing it in styrene-divinylbenzene macroporous resin, and treating it with ammonia soap or sodium soap before use. (4) Desorb the rare earth-loaded resin column with acid to obtain a high-concentration rare earth enriched liquid.

2. The recycling method according to claim 1, characterized in that: The black tungsten slag is the slag produced after alkali decomposition of tungsten ore, and the rare earth content in the slag is 0.1-2%; the concentrated sulfuric acid is commercially available concentrated sulfuric acid; the weight ratio of black tungsten slag to concentrated sulfuric acid is 100:1-100:50; the heating aging temperature is room temperature to 250°C, and the aging time is 0.5-3 hours; in the water-adding stirring leaching process, the weight ratio of water to aging material is 5:1-1:1; the leaching time is 0.5-3 hours.

3. The recycling method according to claim 1, characterized in that: The rare earth-containing leachate is added with alkali to adjust the acidity and control the pH value of the leachate to be 2-4 during the iron removal process; the alkali can be a mixed alkali of one or more of sodium hydroxide, calcium hydroxide, magnesium hydroxide, magnesium oxide, and calcium oxide in any proportion.

4. The recycling method according to claim 1, characterized in that: The leaching resin is prepared by mixing P507 extractant and CA-12 extractant and then cross-linking and polymerizing with styrene and divinylbenzene to form a macroporous leaching resin; the volume ratio of the P507 extractant to the CA-12 extractant is 50:50-90:10; the volume ratio of the mixed extractant to (styrene, divinylbenzene) is 10:90-50:

50.

5. The recycling method according to claim 1, characterized in that: Before the leaching resin is used, ammonia water or sodium hydroxide aqueous solution flows through the resin for saponification treatment, and the saponification degree is controlled to be 30% to 100%.

6. The recycling method according to claim 1, characterized in that: The rare earth-containing iron removal liquid flows through an adsorption column filled with leaching resin for column adsorption to obtain a rare earth-loaded resin column and an adsorption tail liquid; when the rare earth content in the adsorption tail liquid is higher than 0.001 g / L, the rare earth-containing iron removal liquid is stopped and the adsorption process ends.

7. The recycling method according to claim 1, characterized in that: In the acid desorption process, the acid is hydrochloric acid, sulfuric acid, nitric acid or a mixed acid of the three in any proportion; the acidity is 1-6 mol / L; when the rare earth content in the effluent is lower than 0.1 g / L, the acid is stopped and the desorption process ends.