CN115074530B - Method for comprehensively recovering valuable metals from neodymium iron boron waste acid leaching residues under hydrochloric acid system - Google Patents

Method for comprehensively recovering valuable metals from neodymium iron boron waste acid leaching residues under hydrochloric acid system Download PDF

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CN115074530B
CN115074530B CN202210360332.5A CN202210360332A CN115074530B CN 115074530 B CN115074530 B CN 115074530B CN 202210360332 A CN202210360332 A CN 202210360332A CN 115074530 B CN115074530 B CN 115074530B
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acid
ferrous chloride
iron
acid leaching
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CN115074530A (en
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肖燕飞
黄莉
饶明璐
陈金发
文彬
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Jiangxi University of Science and Technology
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B7/00—Working up raw materials other than ores, e.g. scrap, to produce non-ferrous metals and compounds thereof; Methods of a general interest or applied to the winning of more than two metals
    • C22B7/006—Wet processes
    • C22B7/007—Wet processes by acid leaching
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G49/00—Compounds of iron
    • C01G49/02—Oxides; Hydroxides
    • C01G49/06—Ferric oxide (Fe2O3)
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B23/00—Obtaining nickel or cobalt
    • C22B23/04—Obtaining nickel or cobalt by wet processes
    • C22B23/0407—Leaching processes
    • C22B23/0415—Leaching processes with acids or salt solutions except ammonium salts solutions
    • C22B23/0423—Halogenated acids or salts thereof
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B23/00—Obtaining nickel or cobalt
    • C22B23/04—Obtaining nickel or cobalt by wet processes
    • C22B23/0453—Treatment or purification of solutions, e.g. obtained by leaching
    • C22B23/0461—Treatment or purification of solutions, e.g. obtained by leaching by chemical methods
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B59/00—Obtaining rare earth metals
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/30—Particle morphology extending in three dimensions
    • C01P2004/32—Spheres
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/80—Compositional purity
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

Abstract

The invention discloses a method for comprehensively recovering valuable metals from neodymium iron boron waste acid leaching residues under a hydrochloric acid system, which comprises the steps of fully dissolving the acid leaching residues by adopting a hydrochloric acid solution, reducing the obtained acid solution to obtain ferrous chloride-containing solution, then adding sodium hydroxide, sodium sulfide and sodium bicarbonate in stages to realize the fractional precipitation enrichment of the valuable metals, and finally carrying out spray pyrolysis on the high-purity ferrous chloride solution after the valuable metals are recovered to obtain alpha-Fe with spherical morphology and purity reaching more than 99.2 percent 2 O 3 And (3) powder. The invention can enrich and recycle rare earth, cobalt and other elements in the neodymium iron boron waste acid leaching slag, improve the utilization value of iron elements, reduce the stockpiling of solid slag and reduce environmental pollution.

Description

Method for comprehensively recovering valuable metals from neodymium iron boron waste acid leaching residues under hydrochloric acid system
Technical Field
The invention relates to the field of neodymium iron boron waste recovery, in particular to a method for comprehensively recovering valuable metals from neodymium iron boron waste acid leaching residues under a hydrochloric acid system.
Background
With the rapid development of new energy fields, the demand of neodymium-iron-boron magnets is rapidly increased. However, in the production process of the NdFeB magnet, from raw material pretreatment to final product detection, each step inevitably generates waste; in addition, as time goes by, more equipment using neodymium iron boron magnets is scrapped due to the end of service, and a large amount of neodymium iron boron waste is generated, so that the annual production of neodymium iron boron waste is more and more, for example, 2.8 tens of thousands of tons of waste are generated in 2016 China, and 2021 reaches 5.0 tens of thousands of tons. The rare earth content in the NdFeB waste material is about 30%, the main elements include Ce, pr, nd, gd, and the balance is iron, aluminum, cobalt, and the like. Therefore, the neodymium iron boron waste contains valuable elements with higher content, and has higher comprehensive recycling value.
At present, valuable metals in neodymium iron boron waste materials are mainly recovered by a hydrochloric acid optimal dissolution method in industry, and the main processes of the method comprise oxidation roasting, hydrochloric acid optimal dissolution, extraction separation, precipitation roasting and the like. In the oxidizing roasting process of the NdFeB waste, the iron element is fully oxidized to form ferric oxide which is difficult to be acid-soluble, and the rare earth element is oxidized to be rare earth oxide; and then placing the roasting product in hydrochloric acid for optimal dissolution, so that the rare earth oxide is dissolved and leached preferentially. There is still a certain amount of ferric oxide or unoxidized completely in the process of euthanol hydrochlorideThe ferrous oxide is dissolved and leached into the leaching solution, at the moment, the dissolved iron element is precipitated into acid leaching slag in the form of ferric hydroxide by adding an oxidant into the leaching solution and adjusting the pH value of the leaching solution, and finally, the leaching slag is filtered and washed by weak acid to achieve the aim of separating most of rare earth from iron. However, the main component in acid leaching slag is Fe 2 O 3 /Fe(OH) 3 However, the slag still contains rare earth elements, cobalt and other metal elements, which are about a few percent to a few percent. At present, the acid leaching slag is added into a ferrous metallurgy process to recycle iron elements, and valuable metals such as rare earth, cobalt and the like in the slag are not recycled, so that the waste of resources is caused.
For the comprehensive recovery of acid leaching residues, for example, wu Mian and the like, hydrochloric acid is fully dissolved in the research of comprehensive recovery and utilization technology of secondary waste materials of neodymium iron boron magnetic materials, after metal is transferred into a solution, fe is hydrolyzed firstly, beta-FeOOH is obtained by separation, and iron oxide red with the purity of 98.01% is obtained by roasting; then the hydrolyzed solution is treated with NH 4 HCO 3 Precipitating agent, and recovering rare earth and cobalt by regulating pH to obtain the final product. However, in the Fe/RE/Co precipitation separation process, the comprehensive recovery rate of relevant valuable metals is not high, and the iron is 89%, the cobalt is 88% and the rare earth is 79%. Meanwhile, in the patent CN201610246932.3, sulfuric acid is adopted to decompose acid slag, and then Fe is reduced by scrap iron 3+ Fe generation 2+ In the patent, rare earth/cobalt elements in acid leaching slag are recovered and enriched step by step in a solution in the processes of acid decomposition, purification and impurity removal and iron oxide red washing, the whole process flow is very complex, the industrial production efficiency is seriously affected, and meanwhile, the requirement on equipment is high. Patent CN201810865627.1 recovers rare earth elements in a multistage pickling mode, but the recovery rate is not high, the concentration of the obtained solution is low, and rare earth enrichment is difficult; cobalt is not well collected. CN201910009567.8 adopts flash reduction to separate iron and rare earth, thereby efficiently recovering rare earth and iron.
In summary, how to provide a method for efficiently separating valuable elements such as rare earth and iron under the condition that iron element occupies the main body for comprehensive recovery of acid leaching residues generated in the neodymium iron boron waste recovery process, and simultaneously, to perform high-value utilization on the iron element so as to improve the recovery benefit of industrial waste, has become the technical problem to be solved in urgent need at present.
Disclosure of Invention
The invention mainly aims to develop a method for treating neodymium iron boron waste acid leaching slag so as to enrich and recycle elements such as rare earth, cobalt and the like, improve the utilization value of iron elements, reduce the stockpiling of solid slag and reduce environmental pollution.
In order to achieve the aim, the method for comprehensively recovering valuable metals from neodymium iron boron waste acid leaching residues under a hydrochloric acid system is provided, and specifically comprises the following steps of.
(1) Acid leaching slag two-stage countercurrent acid dissolution reduction: carrying out two-stage countercurrent acid leaching on acid leaching residues by adopting a hydrochloric acid solution with the concentration of 6.0-9.0mol/L, controlling the temperature to be 60-90 ℃, and carrying out solid-liquid separation to obtain an acid solution and acid leaching residues; then introducing a reducing agent to carry out reduction treatment on the acid solution to obtain a ferrous chloride-containing solution.
(2) Fractional precipitation and enrichment of valuable metals: firstly, adding sodium hydroxide solution into the ferrous chloride-containing solution to adjust the pH value to 3.1-3.4, then adding sodium sulfide solution, wherein the adding amount of sodium sulfide is 3-6 times of the theoretical dosage required by complete precipitation of cobalt ions in the ferrous chloride-containing solution, finally adding mixed solution containing sodium sulfide and sodium bicarbonate, adjusting the pH value of the ferrous chloride-containing solution to 4.4-4.7, and carrying out solid-liquid separation to obtain high-purity ferrous chloride solution and valuable metal enrichment.
(3) Spray pyrolysis to prepare iron oxide red: diluting high-purity ferrous chloride solution to 30-60g/L, wherein the concentration is calculated by iron ion, and then performing spray pyrolysis to prepare alpha-Fe 2 O 3 And (3) powder.
Further, the molar ratio of sodium sulfide to sodium bicarbonate in the mixed solution containing sodium sulfide and sodium bicarbonate is 0.2-0.45.
Further, one or more of tartaric acid, malic acid, phytic acid, polyvinyl alcohol, hydroxylamine salt and citric acid are added into the ferrous chloride-containing solution before the step of fractional precipitation and enrichment of the valuable metals.
Further, the reducing agent is waste iron sheet.
Further, the spray pyrolysis temperature is 700-1100 ℃.
Further, the obtained alpha-Fe 2 O 3 The powder is spherical in shape, and the purity reaches more than 99.2%.
According to the composition and characteristics of neodymium iron boron waste acid leaching residues, the invention better realizes the recovery of valuable metals such as rare earth and cobalt and the high-value utilization of iron elements by fully separating iron ions from other non-iron ions, adopts 6.0-9.0mol/L hydrochloric acid to fully dissolve the acid leaching residues at 60-90 ℃, reduces the obtained acid solution to obtain ferrous chloride-containing solution, realizes the fractional precipitation enrichment of the valuable metals by adding sodium hydroxide, sodium sulfide and sodium bicarbonate, can recover the elements such as rare earth and cobalt as far as possible by controlling the adding sequence and the using amount of a precipitant, and reduces the loss rate of iron; before adding the precipitant, preferably adding one or more of tartaric acid, malic acid, phytic acid, polyvinyl alcohol, hydroxylamine salt and citric acid into the ferrous chloride-containing solution, so as to separate iron ions and rare earth/cobalt ions more efficiently; finally, spray pyrolysis is carried out on the obtained high-purity ferrous chloride solution at 700-1100 ℃ to obtain the alpha-Fe with spherical morphology and purity of more than 99.2 percent 2 O 3 And (3) powder.
Detailed Description
It should be noted that, in the case of no conflict, the embodiments and features in the embodiments may be combined with each other. The present application will be described in detail with reference to examples.
The existing method for recovering valuable metals from neodymium iron boron waste acid slag mainly comprises a flash method, an acid dissolution-precipitation method and the like, but the methods have some defects, such as low recovery rate of rare earth, cobalt and the like, low purity of iron oxide red and the like, and limit the application field of the method.
The invention provides a method for comprehensively recovering valuable metals from neodymium iron boron waste acid leaching residues under a hydrochloric acid system, so as to realize recovery of valuable metals such as rare earth, cobalt and the like and high-value utilization of iron elements. The method specifically comprises the following steps.
(1) Acid leaching slag two-stage countercurrent acid dissolution reduction: carrying out two-stage countercurrent acid leaching on acid leaching residues by adopting a hydrochloric acid solution with the concentration of 6.0-9.0mol/L, controlling the temperature to be 60-90 ℃, and carrying out solid-liquid separation to obtain an acid solution and acid leaching residues; at this time, the leaching rate of rare earth reaches more than 95%, the leaching rate of cobalt reaches more than 98%, and the leaching rate of iron exceeds 90%. Then introducing a reducing agent to carry out reduction treatment on the acid solution to obtain a ferrous chloride-containing solution, detecting red-free precipitate generation by adopting KSCN (K-Si) in the solution, wherein the content of ferric ions in the ferrous chloride-containing solution is less than 0.2g/L; the reducing agent is preferably waste iron sheet, so that waste resources can be fully utilized, other impurities are not introduced, and the concentration of iron element in the ferrous chloride-containing solution can be increased.
(2) Fractional precipitation and enrichment of valuable metals: firstly, adding a sodium hydroxide solution into a ferrous chloride-containing solution to adjust the pH to 3.1-3.4, and carrying out precipitation hydrolysis on all aluminum ions in the solution, so that the existence of the aluminum ions can be avoided, and the consumption of a subsequent sodium sulfate precipitant can be prevented from being increased; then adding sodium sulfide solution, wherein the adding amount of sodium sulfide is 3-6 times of the theoretical dosage required by complete precipitation of cobalt ions in the ferrous chloride-containing solution, and precipitating most of cobalt ions in the solution; finally, adding a mixed solution of sodium sulfide and sodium bicarbonate, regulating the pH of the ferrous chloride solution to 4.4-4.7, at the moment, basically precipitating rare earth ions and residual cobalt ions, and finally, carrying out solid-liquid separation to obtain a high-purity ferrous chloride solution and valuable metal enrichment; in the whole process, the precipitation rate of rare earth and cobalt elements is more than 95%, the precipitation rate of aluminum is more than 99%, and the loss rate of ferrous ions is less than 5%. Especially, the order of the three precipitants can not be adjusted, which is easy to cause the problems of large sodium sulfide consumption, high ferrous precipitation rate, low valuable metal precipitation rate and the like; moreover, for the mixed solution of sodium sulfide and sodium bicarbonate, sodium sulfide or sodium bicarbonate alone solution cannot be simply used as a precipitant, because if sodium sulfide is used as a separate precipitant, rare earth ions are incompletely precipitated; if sodium bicarbonate is used as a precipitator, cobalt ions are incompletely precipitated; if sodium sulfide or sodium bicarbonate precipitant is to be used to precipitate most of the cobalt and rare earth, the iron loss rate increases significantly. Meanwhile, the molar ratio of sodium sulfide to sodium bicarbonate in the mixed solution of sodium sulfide and sodium bicarbonate is 0.2-0.45, and the rare earth/cobalt and iron elements can be better separated under the condition. If the molar ratio is more than 0.45, the alkalinity of the mixed solution is higher, so that more carbonate is contained in the solution, and the precipitation rate of iron element is increased in the precipitation process; if the molar ratio is less than 0.2, most of the precipitation of cobalt cannot be achieved while the rare earth precipitation is complete. In particular, one or more of tartaric acid, malic acid, phytic acid, polyvinyl alcohol, hydroxylamine salts and citric acid are preferably added to the ferrous chloride prior to the step of fractional precipitation and enrichment of the valuable metal. The addition of the auxiliary agents can more preferentially complex ferrous ions, so that when rare earth or cobalt is precipitated, the precipitation of iron is reduced, the yield of iron element is finally improved, and meanwhile, the purity of rare earth and cobalt in valuable metal enrichment is increased.
(3) Spray pyrolysis to prepare iron oxide red: diluting high-purity ferrous chloride solution to 30-60g/L, wherein the concentration is calculated by iron ion, then performing spray pyrolysis at 700-1100 ℃ to prepare the obtained alpha-Fe 2 O 3 And (3) powder. alpha-Fe obtained 2 O 3 The powder is spherical in shape, and the purity reaches more than 99.2%.
The method for comprehensively recovering valuable metals from neodymium iron boron waste acid leaching residues under the hydrochloric acid system is further described in the following with reference to examples.
Comparative example 1
Taking 10g of neodymium iron boron waste acid leaching slag, carrying out two-stage countercurrent leaching on the acid leaching slag by adopting 40mL of 8.0mol/L hydrochloric acid solution, controlling the reaction temperature to be 80 ℃, and carrying out solid-liquid separation to obtain an acid solution and acid leaching slag, wherein the leaching rate of rare earth is 95.6%, the leaching rate of cobalt is 98.4%, and the leaching rate of iron is 91.2%; and then adopting waste iron sheets to carry out reduction treatment on the acid solution until the solution adopts KSCN to detect red precipitate generation, thus obtaining the ferrous chloride-containing solution. Adding sodium hydroxide solution into the ferrous chloride-containing solution to adjust the pH to 3.2, and then adding 0.4mol/L sodium sulfide solution, wherein the addition amount of the sodium sulfide solution is 6 times of the theoretical amount required by complete precipitation of cobalt ions in the ferrous chloride-containing solutionThe solid-liquid separation is carried out to obtain high-purity ferrous chloride solution and valuable metal enrichment, at the moment, the precipitation rate of aluminum ions is 99.1%, the precipitation rate of rare earth ions is 31.5%, the precipitation rate of cobalt ions is 90.2%, and the precipitation rate of iron ions is 0.8%. Diluting high-purity ferrous chloride solution with purified water to 45g/L, wherein the concentration is calculated by iron ion, and then performing spray pyrolysis at 800 ℃ to prepare the alpha-Fe with spherical morphology and 97.6% purity 2 O 3 And (3) powder.
Comparative example 2
Taking 10g of neodymium iron boron waste acid leaching slag, carrying out two-stage countercurrent leaching on the acid leaching slag by adopting 40mL of 8.0mol/L hydrochloric acid solution, controlling the reaction temperature to be 80 ℃, and carrying out solid-liquid separation to obtain an acid solution and acid leaching slag, wherein the leaching rate of rare earth is 95.6%, the leaching rate of cobalt is 98.4%, and the leaching rate of iron is 91.2%; and then adopting waste iron sheets to carry out reduction treatment on the acid solution until the solution adopts KSCN to detect red precipitate generation, thus obtaining the ferrous chloride-containing solution. Adding sodium hydroxide solution into the ferrous chloride-containing solution to adjust the pH value to 3.2, adding 0.4mol/L sodium sulfide solution, wherein the addition amount of the sodium sulfide solution is 6 times of the theoretical dosage required by complete precipitation of cobalt ions in the ferrous chloride-containing solution, finally adding a mixed solution with the molar ratio of sodium sulfide to sodium bicarbonate being 0.6, adjusting the pH value of the ferrous chloride solution to 4.6, and carrying out solid-liquid separation to obtain a high-purity ferrous chloride solution and valuable metal enrichment, wherein the precipitation rate of aluminum ions is 99.2%, the precipitation rate of rare earth ions is 86.2%, the precipitation rate of cobalt ions is 96.2%, and the precipitation rate of iron ions is 9.1%. Diluting high-purity ferrous chloride solution with purified water to 45g/L, wherein the concentration is calculated by iron ion, and then performing spray pyrolysis at 800 ℃ to prepare the alpha-Fe with spherical morphology and purity of 98.1% 2 O 3 And (3) powder.
Comparative example 3
Taking 10g of neodymium iron boron waste acid leaching slag, carrying out two-stage countercurrent leaching on the acid leaching slag by adopting 40mL of 8.0mol/L hydrochloric acid solution, controlling the reaction temperature to be 80 ℃, and carrying out solid-liquid separation to obtain an acid solution and acid leaching slag, wherein the leaching rate of rare earth is 95.6%, the leaching rate of cobalt is 98.4%, and the leaching rate of iron is 91.2%; then the acid solution is reduced by adopting the waste iron sheetAnd (3) treating until the solution adopts KSCN to detect the generation of red precipitate, and obtaining the ferrous chloride-containing solution. Adding sodium hydroxide solution into the ferrous chloride-containing solution to adjust the pH to 3.2, adding a mixed solution with the molar ratio of sodium sulfide to sodium bicarbonate being 0.4, adjusting the pH of the ferrous chloride solution to 4.6, and carrying out solid-liquid separation to obtain a high-purity ferrous chloride solution and valuable metal enrichment, wherein the precipitation rate of aluminum ions is 99.2%, the precipitation rate of rare earth ions is 96.1%, the precipitation rate of cobalt ions is 86.4%, and the precipitation rate of iron ions is 8.3%. Diluting high-purity ferrous chloride solution with purified water to 45g/L, wherein the concentration is calculated by iron ion, and then performing spray pyrolysis at 800 ℃ to prepare the alpha-Fe with spherical morphology and 97.8% purity 2 O 3 And (3) powder.
Comparative example 4
Taking 10g of neodymium iron boron waste acid leaching slag, carrying out two-stage countercurrent leaching on the acid leaching slag by adopting 40mL of 8.0mol/L hydrochloric acid solution, controlling the reaction temperature to be 80 ℃, and carrying out solid-liquid separation to obtain an acid solution and acid leaching slag, wherein the leaching rate of rare earth is 95.6%, the leaching rate of cobalt is 98.4%, and the leaching rate of iron is 91.2%; and then adopting waste iron sheets to carry out reduction treatment on the acid solution until the solution adopts KSCN to detect red precipitate generation, thus obtaining the ferrous chloride-containing solution. Adding sodium hydroxide solution into the ferrous chloride-containing solution to adjust the pH value to 3.2, adding 0.4mol/L sodium sulfide solution, wherein the addition amount of the sodium sulfide solution is 6 times of the theoretical dosage required by complete precipitation of cobalt ions in the ferrous chloride-containing solution, finally adding sodium bicarbonate solution to adjust the pH value of the ferrous chloride solution to 4.6, and carrying out solid-liquid separation to obtain high-purity ferrous chloride solution and valuable metal enrichment, wherein the precipitation rate of aluminum ions is 99.2%, the precipitation rate of rare earth ions is 97.1%, the precipitation rate of cobalt ions is 83.2%, and the precipitation rate of iron ions is 6.8%. Diluting high-purity ferrous chloride solution with purified water to 45g/L, wherein the concentration is calculated by iron ion, and then performing spray pyrolysis at 800 ℃ to prepare the alpha-Fe with spherical morphology and 97.9% purity 2 O 3 And (3) powder.
Example 1
10g of NdFeB waste acid leaching residue is taken, 40mL of 8.0mol/L hydrochloric acid solution is adopted to carry out two-stage reverse reaction on the acid leaching residueCarrying out flow leaching, controlling the reaction temperature to be 80 ℃, and carrying out solid-liquid separation to obtain an acid solution and acid-soluble slag, wherein the leaching rate of rare earth is 95.6%, the leaching rate of cobalt is 98.4%, and the leaching rate of iron is 91.2%; and then adopting waste iron sheets to carry out reduction treatment on the acid solution until the solution adopts KSCN to detect red precipitate generation, thus obtaining the ferrous chloride-containing solution. Adding sodium hydroxide solution into the ferrous chloride-containing solution to adjust the pH value to 3.2, adding 0.4mol/L sodium sulfide solution, wherein the addition amount of the sodium sulfide solution is 6 times of the theoretical dosage required by complete precipitation of cobalt ions in the ferrous chloride-containing solution, finally adding a mixed solution with the molar ratio of sodium sulfide to sodium bicarbonate being 0.4, adjusting the pH value of the ferrous chloride solution to 4.6, and carrying out solid-liquid separation to obtain a high-purity ferrous chloride solution and valuable metal enrichment, wherein the precipitation rate of aluminum ions is 99.2%, the precipitation rate of rare earth ions is 96.5%, the precipitation rate of cobalt ions is 96.2%, and the precipitation rate of iron ions is 4.4%. Diluting high-purity ferrous chloride solution with purified water to 45g/L, wherein the concentration is calculated by iron ion, and then carrying out spray pyrolysis at 800 ℃ to prepare the alpha-Fe with spherical morphology and purity up to 99.2 percent 2 O 3 And (3) powder.
Example 2
Taking 10g of neodymium iron boron waste acid leaching slag, carrying out two-stage countercurrent leaching on the acid leaching slag by adopting 40mL of 7.0mol/L hydrochloric acid solution, controlling the reaction temperature to 90 ℃, and carrying out solid-liquid separation to obtain an acid solution and acid leaching slag, wherein the leaching rate of rare earth is 96.4%, the leaching rate of cobalt is 99.1%, and the leaching rate of iron is 92.0%; and then carrying out reduction treatment on the acid solution by adopting ascorbic acid until the solution adopts KSCN to detect the generation of red precipitate, thereby obtaining the ferrous chloride-containing solution. Adding sodium hydroxide solution into ferrous chloride-containing solution to adjust pH to 3.3, adding 0.4mol/L sodium sulfide solution with an addition amount which is 4 times of the theoretical dosage required by complete precipitation of cobalt ions in the ferrous chloride-containing solution, finally adding mixed solution with a molar ratio of sodium sulfide to sodium bicarbonate of 0.3, adjusting pH of the ferrous chloride solution to 4.5, and carrying out solid-liquid separation to obtain high-purity ferrous chloride solution and valuable metal enrichment, wherein the precipitation rate of aluminum ions is 99.2%, the precipitation rate of rare earth ions is 95.7%, the precipitation rate of cobalt ions is 96.7%, and the precipitation rate of iron ions is 4.0%. Diluting high-purity ferrous chloride solution with purified water to 55g/L, wherein the concentration is calculated by iron ion, and then performing spray pyrolysis at 1000 ℃ to prepare alpha-Fe with spherical morphology and purity up to 99.4% 2 O 3 And (3) powder.
Example 3
Taking 10g of neodymium iron boron waste acid leaching slag, carrying out two-stage countercurrent leaching on the acid leaching slag by adopting 40mL of 9.0mol/L hydrochloric acid solution, controlling the reaction temperature to be 70 ℃, and carrying out solid-liquid separation to obtain an acid solution and acid leaching slag, wherein the leaching rate of rare earth is 95.6%, the leaching rate of cobalt is 98.6%, and the leaching rate of iron is 91.4%; and then adopting waste iron sheets to carry out reduction treatment on the acid solution until the solution adopts KSCN to detect red precipitate generation, thus obtaining the ferrous chloride-containing solution. Tartaric acid is added into the ferrous chloride-containing solution to enable the concentration of tartaric acid in the solution to be 0.5g/L, a sodium hydroxide solution is adopted to adjust the pH value to 3.1, then a sodium sulfide solution with the concentration of 0.4mol/L is added, the addition amount of the sodium sulfide solution is 5 times of the theoretical amount required by complete precipitation of cobalt ions in the ferrous chloride-containing solution, finally a mixed solution with the molar ratio of sodium sulfide to sodium bicarbonate being 0.2 is added, the pH value of the ferrous chloride solution is adjusted to be 4.7, the solid-liquid separation is carried out to obtain a high-purity ferrous chloride solution and valuable metal enrichment, at the moment, the precipitation rate of aluminum ions is 99.3%, the precipitation rate of rare earth ions is 96.9%, the precipitation rate of cobalt ions is 97.7%, and the precipitation rate of iron ions is 3.5%. Diluting high-purity ferrous chloride solution with purified water to 30g/L, wherein the concentration is calculated by iron ion, and then performing spray pyrolysis at 700 ℃ to prepare alpha-Fe with spherical morphology and purity up to 99.5% 2 O 3 And (3) powder.
Example 4
Taking 10g of neodymium iron boron waste acid leaching slag, carrying out two-stage countercurrent leaching on the acid leaching slag by adopting 40mL of 6.0mol/L hydrochloric acid solution, controlling the reaction temperature to 65 ℃, and carrying out solid-liquid separation to obtain an acid solution and acid leaching slag, wherein the leaching rate of rare earth is 95.3%, the leaching rate of cobalt is 98.9%, and the leaching rate of iron is 91.8%; and then adopting waste iron sheets to carry out reduction treatment on the acid solution until the solution adopts KSCN to detect red precipitate generation, thus obtaining the ferrous chloride-containing solution. Adding phytic acid into the solution containing ferrous chloride to make the phytic acid in the solution be concentratedThe degree is 1.0g/L, the pH value is regulated to 3.4 by adopting sodium hydroxide solution, then 0.4mol/L sodium sulfide solution is added, the addition amount of the sodium sulfide solution is 3 times of the theoretical amount required by complete precipitation of cobalt ions in the ferrous chloride-containing solution, finally, the mixed solution of sodium sulfide and sodium bicarbonate with the mol ratio of 0.45 is added, the pH value of the ferrous chloride solution is regulated to 4.4, the solid-liquid separation is carried out to obtain high-purity ferrous chloride solution and valuable metal enrichment, at the moment, the precipitation rate of aluminum ions is 99.4%, the precipitation rate of rare earth ions is 96.1%, the precipitation rate of cobalt ions is 98.7%, and the precipitation rate of iron ions is 3.2%. Diluting high-purity ferrous chloride solution with purified water to 60g/L, wherein the concentration is calculated by iron ions, and then carrying out spray pyrolysis at 900 ℃ to prepare the alpha-Fe with spherical morphology and purity up to 99.4 percent 2 O 3 And (3) powder.

Claims (5)

1. The method for comprehensively recovering valuable metals from neodymium iron boron waste acid leaching residues in a hydrochloric acid system is characterized by comprising the following steps of:
(1) Acid leaching slag two-stage countercurrent acid dissolution reduction: carrying out two-stage countercurrent acid leaching on acid leaching residues by adopting a hydrochloric acid solution with the concentration of 6.0-9.0mol/L, controlling the temperature to be 60-90 ℃, and carrying out solid-liquid separation to obtain an acid solution and acid leaching residues; then introducing a reducing agent to carry out reduction treatment on the acid solution to obtain a ferrous chloride-containing solution;
(2) Fractional precipitation and enrichment of valuable metals: firstly, adding a sodium hydroxide solution into the ferrous chloride-containing solution to adjust the pH to 3.1-3.4, then adding a sodium sulfide solution, wherein the addition amount of the sodium sulfide is 3-6 times of the theoretical dosage required by complete precipitation of cobalt ions in the ferrous chloride-containing solution, finally adding a mixed solution containing sodium sulfide and sodium bicarbonate, adjusting the pH of the ferrous chloride-containing solution to 4.4-4.7, and carrying out solid-liquid separation to obtain a high-purity ferrous chloride solution and valuable metal enrichment; the molar ratio of the sodium sulfide to the sodium bicarbonate in the mixed solution containing the sodium sulfide and the sodium bicarbonate is 0.2-0.45
(3) Spray pyrolysis to prepare iron oxide red: diluting high-purity ferrous chloride solution to 30-60g/L, wherein the concentration is calculated by iron ion, and then performing spray pyrolysis to prepare alpha-Fe 2 O 3 And (3) powder.
2. The method of claim 1, wherein one or more of tartaric acid, malic acid, phytic acid, polyvinyl alcohol, hydroxylamine salts, citric acid are added to the acid solution prior to step (2).
3. The method of claim 1, wherein the reducing agent is scrap iron.
4. The method of claim 1, wherein the spray pyrolysis temperature is 700-1100 ℃.
5. The method according to claim 1, wherein α -Fe 2 O 3 The powder is spherical in shape, and the purity reaches more than 99.2%.
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GB662051A (en) * 1948-01-06 1951-11-28 Davide Primavesi Improved chemical process for producing powdered iron
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