A method for recovering cobalt intermediates

Abstract

This disclosure belongs to the field of hydrometallurgical technology, specifically relating to a method for recovering cobalt intermediates. The method involves first preparing a slurry from the cobalt intermediate, followed by neutral leaching, reducing acid leaching, and high-acid leaching. During neutral leaching, ferrous iron is oxidized to ferric iron, while ferric cobalt is reduced to ferrous cobalt. Neutral leaching removes most of the cobalt while simultaneously co-precipitating impurities such as copper and aluminum with ferric hydroxide. Reducing acid leaching reduces the high-valent cobalt in the neutral leaching residue to ferrous cobalt ions, achieving efficient leaching of the neutral residue. The acid leaching residue obtained after reducing acid leaching is then subjected to high-acid leaching to maximize the recovery of cobalt metal from the acid leaching residue, thereby improving the cobalt recovery rate.

Description

TECHNICAL FIELD

[0001] The present disclosure belongs to the technical field of hydrometallurgy, and in particular, relates to a cobalt intermediate recovery method. BACKGROUND

[0002] Non-ferrous metals are the basic materials for the development of the national economy. With the rapid development of economy, the demand for non-ferrous metals is increasing, and the non-ferrous metal extraction metallurgy technology should also be continuously innovated with the development of science and technology. Hydrometallurgy is an important technical means in the field of metallurgy, which is a scientific and technological method of realizing metal separation, enrichment and extraction by converting ore, concentrate enriched by ore dressing or other raw materials into liquid phase through leaching agent. Generally speaking, hydrometallurgy includes leaching, metal enrichment, solution purification and other processes.

[0003] Recovering valuable metals such as cobalt from cobalt solution has good economic value. While recovering cobalt, iron in the cobalt solution also needs to be effectively removed. The currently widely used iron removal methods mainly include the following methods:

[0004] (1) Chemical precipitation method

[0005] The chemical precipitation method is to convert the iron ions in the cobalt leaching solution into a precipitate through a chemical reaction, and then perform solid-liquid separation to achieve the purpose of iron removal. This method has the advantages of simple operation, low cost, good iron removal effect, etc., but also has the disadvantages of large amount of slag and difficult filtration.

[0006] (2) Oxidation precipitation method

[0007] The oxidation precipitation method mainly uses oxidizing agents such as oxygen and hydrogen peroxide to oxidize iron ions to trivalent iron ions by redox, and the iron ions are precipitated by controlling the concentration of iron ions. The goethite method has the advantages of fast iron removal speed and good effect, but also has the disadvantages of high reaction condition requirement and difficulty in achieving process conditions in actual production.

[0008] The existing iron removal methods in cobalt solution generally have the problems of large amount of slag and high cost. In addition, the existing cobalt solution recovery method needs to be solved is to effectively improve the cobalt recovery rate.

[0009] In view of this, the present disclosure is proposed. SUMMARY

[0010] The purpose of the present disclosure includes providing a cobalt intermediate recovery method, which aims to significantly improve the cobalt recovery rate.

[0011] In order to achieve the above purpose of the present disclosure, the following technical solutions can be used:

[0012] The scheme provided by the present disclosure comprises a cobalt intermediate recovery method, which comprises: mixing the cobalt intermediate and sulfuric acid, performing neutral leaching under an oxidation condition, controlling the pH value of the leaching to be 5.0-5.4, and obtaining neutral leaching residue and post-leaching liquid;

[0013] The neutral leaching residue is subjected to reduction acid leaching to obtain acid leaching residue and acid leaching liquid;

[0014] The acid leaching residue is subjected to high-acid leaching, and the pH value is controlled to be less than 0.5 to obtain high-acid leaching liquid;

[0015] The high-acid leaching liquid is returned to the neutral leaching stage.

[0016] In some embodiments of the present disclosure, the process of neutral leaching comprises: mixing the cobalt intermediate with water to obtain cobalt intermediate slurry, the mass fraction of the cobalt intermediate in the cobalt intermediate slurry being 13%-15%, mixing the cobalt intermediate slurry with sulfuric acid and an oxidizing agent for reaction, and controlling the leaching temperature to be 50°C-70°C and the reaction time to be 1.5h-1.6h.

[0017] In some embodiments of the present disclosure, when the mass fraction of iron in the cobalt intermediate is less than 0.5%, ferrous sulfate is supplemented to participate in the reaction of neutral leaching, and the mass ratio of the ferrous sulfate supplement amount to the cobalt metal amount in the cobalt intermediate is (4-6):100.

[0018] In some embodiments of the present disclosure, in the process of neutral leaching, a plurality of reaction kettles are connected in series, the cobalt intermediate slurry, sulfuric acid and an oxidizing agent are added to the first reaction kettle, the cobalt intermediate slurry is added to the intermediate reaction kettles, the pH value of the leaching is controlled to be 5.0-5.4, and the residence time in each reaction kettle is 1.5h-1.6h.

[0019] When the mass fraction of iron in the cobalt intermediate is less than 0.5%, ferrous sulfate is additionally added to the first reaction kettle.

[0020] In some embodiments of the present disclosure, the oxidizing agent is selected from at least one of oxygen-containing gas and hydrogen peroxide.

[0021] In some embodiments of the present disclosure, the oxygen-containing gas is selected from at least one of air and oxygen-enriched gas, and the volume fraction of oxygen in the oxygen-enriched gas is 21%-90%.

[0022] In some embodiments of the present disclosure, the process of reduction acid leaching comprises: mixing the neutral leaching residue with water to slurry, and then mixing with sulfuric acid and a reducing agent, the leaching temperature being 60°C-80°C and the leaching time being greater than 2h.

[0023] In some embodiments of the present disclosure, the leaching temperature of the reduction acid leaching is 65°C-75°C, the leaching time is 3h-4h, and the leaching pH value is 1.5-2.0.

[0024] In some embodiments of the present disclosure, the reducing agent is selected from at least one of sulfur dioxide, ammonium pyrosulfite and hydrogen peroxide.

[0025] In some embodiments of the present disclosure, the reducing agent is sulfur dioxide.

[0026] In some embodiments of the present disclosure, the amount of sulfur dioxide is 0.1-1 Nm 3 / m 3 .

[0027] In some embodiments of the present disclosure, the sulfur dioxide generated in the acid production system is dried and compressed and then introduced into the reactor for the reduction acid leaching.

[0028] In some embodiments of the present disclosure, the mass ratio of the neutral leaching residue to water is 1: (3-5).

[0029] In some embodiments of the present disclosure, the high-acid leaching process comprises mixing the acid leaching residue with hydrogen peroxide and sulfuric acid, controlling the reaction temperature to be 85-95℃, the reaction pH value to be 0.25-0.45, and the leaching time to be 4-5h.

[0030] In some embodiments of the present disclosure, the process further comprises mixing the acid leaching solution generated in the reduction acid leaching process with iron powder to perform a copper removal reaction, obtaining a copper-removed solution, and introducing the copper-removed solution into the iron removal process.

[0031] In some embodiments of the present disclosure, the concentration of copper ions in the copper-removed solution is controlled to be 50-200mg / L by adjusting the amount of iron powder.

[0032] In some embodiments of the present disclosure, the process of the iron removal process comprises mixing the copper-removed solution with an oxygen-containing gas, a neutralizing agent and a nucleation agent, controlling the reaction pH value to be 3.0-3.5, and keeping the concentration of Fe 3+ in the system to be less than 1g / L during the process.

[0033] In some embodiments of the present disclosure, the reaction temperature in the iron removal process is controlled to be 80-90℃ and the reaction time is controlled to be 2-3h.

[0034] In some embodiments of the present disclosure, the oxygen-containing gas is selected from at least one of air and oxygen-enriched gas, and the oxygen volume fraction in the oxygen-enriched gas is 21-90%.

[0035] In some embodiments of the present disclosure, the flow rate of the oxygen-containing gas is adjusted according to the volume of the solution, and the flow rate of the oxygen-containing gas is 0.1-1.0 Nm 3 / m 3 -1.0 Nm 3 / m 3 .

[0036] In some embodiments of the present disclosure, the neutralizing agent is selected from at least one of cobalt carbonate and cobalt intermediates.

[0037] In some embodiments of the present disclosure, the nucleation agent is calcium carbonate.

[0038] In some embodiments of the present disclosure, by controlling the amount of the nucleation agent, the concentration of the generated calcium sulfate crystals is 1g / m 3 -100g / m 3 .

[0039] In some embodiments of the present disclosure, the iron removal process is a continuous iron removal process, including a first reaction tank, a second reaction tank, a third reaction tank and a fourth reaction tank connected in series, the first reaction tank is added with the copper-removed solution, an oxygen-containing gas and a neutralizing agent, the second reaction tank is added with the copper-removed solution, a neutralizing agent and a nucleation agent, the third reaction tank is added with the oxygen-containing gas, and the material output from the fourth reaction tank is subjected to solid-liquid separation, and the liquid material obtained is returned to the first reaction tank when the Fe 3+ concentration is greater than 1g / L.

[0040] In some embodiments of the present disclosure, the residence time of the first reaction tank, the second reaction tank, the third reaction tank and the fourth reaction tank is 1.5h-2.5h.

[0041] By sequentially performing neutral leaching, reduction acid leaching and high-acid leaching on the cobalt intermediate, the divalent iron is oxidized to trivalent iron in the process of neutral leaching, and at the same time, the trivalent cobalt is reduced to divalent cobalt, most of the cobalt can be leached through neutral leaching, and at the same time, copper, aluminum and other impurities are co-precipitated with iron hydroxide; the residual high-valence cobalt in the neutral leaching residue is reduced to divalent cobalt ions through reduction acid leaching, realizing efficient leaching of the neutral residue; the acid leaching residue obtained after reduction acid leaching is subjected to high-acid leaching, so as to maximize the recovery of cobalt metal in the acid leaching residue and improve the cobalt recovery rate. BRIEF DESCRIPTION OF DRAWINGS

[0042] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings needed in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present disclosure, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0043] Figure 1 A full flow chart for multi-stage leaching and continuous iron removal crystallization process of cobalt intermediate;

[0044] Figure 2 A process chart for neutral leaching of cobalt intermediate;

[0045] Figure 3 for sulfur dioxide reduction acid leaching process diagram;

[0046] Figure 4 for continuous iron removal crystallization process diagram. DETAILED DESCRIPTION

[0047] The embodiments of the present disclosure will be described in detail below with examples, but those skilled in the art will understand that the following examples are only for illustration of the present disclosure and should not be regarded as limiting the scope of the present disclosure. The specific conditions are not specified in the examples, and the conventional conditions or the conditions recommended by the manufacturer are used. The reagents or instruments used are not specified by the manufacturer, and are conventional products that can be obtained by commercial purchase.

[0048] The endpoints of the ranges and any values disclosed in the present disclosure are not limited to the precise values stated. The ranges and values should be interpreted as being approximate. For numeric values, the endpoints of the ranges, the endpoints of the ranges and individual point values, and individual point values can be combined with each other to obtain one or more new numeric ranges, which should be considered as specifically disclosed herein.

[0049] Cobalt intermediate preparation process: the raw material is copper-cobalt ore, sulfuric acid leaching is used to obtain a copper-containing and cobalt-containing leaching solution, an extractant is used to extract copper from the leaching solution, the raffinate after copper removal is subjected to iron removal to obtain a post-iron removal solution, and then active magnesium oxide is used to adjust the pH value to precipitate cobalt to obtain a cobalt intermediate mainly composed of crude cobalt hydroxide (Co(OH)2), which contains other impurities such as Ni, Mg, Mn, a small amount of Fe, Cu, Al, etc.

[0050] The present disclosure provides a cobalt intermediate recovery method, as shown in Figure 1 , comprising the following steps:

[0051] S1, neutral leaching

[0052] The cobalt intermediate and sulfuric acid are mixed, and neutral leaching is carried out under oxidation conditions, the pH value of the leaching is controlled to be 5.0-5.4, and neutral leaching residue and post-leaching solution are obtained. In this process, ferrous ions are oxidized at the same time, and trivalent cobalt ions are reduced to divalent cobalt (principle as shown in the chemical equation), so as to achieve the purpose of leaching most of the cobalt, and at the same time, through the regulation of the hydrolysis process of iron ions, trivalent iron ions are hydrolyzed and precipitated to form neutral leaching residue, and copper, aluminum and other impurities are enriched in the neutral leaching residue by neutralization and hydrolysis and co-precipitation.

[0053] 6Fe 2+ +3 / 2O2+6H + ==6Fe 3+ +3H2O;

[0054] 3Fe 2+ +2Co 3+ ==2Co 2+ +3Fe 3+ ;

[0055] Specifically, the leaching pH value can be 5.0, 5.1, 5.2, 5.3, 5.4, etc., and the pH value can be made to meet the requirements by adjusting the amount of sulfuric acid or cobalt intermediate slurry.

[0056] In some embodiments of this disclosure, the neutral leaching process includes: mixing a cobalt intermediate with water to form a slurry, wherein the mass fraction of the cobalt intermediate in the slurry is 13%-15%; mixing the cobalt intermediate slurry with sulfuric acid and an oxidant; controlling the leaching temperature at 50°C-70°C; and the reaction time at 1.5-1.6 hours. Specifically, the mass fraction of the cobalt intermediate in the slurry can be 13%, 14%, 15%, etc.; the leaching temperature can be 50°C, 55°C, 60°C, 65°C, 70°C, etc.; and the reaction time can be 1.50 hours, 1.55 hours, 1.60 hours, etc.

[0057] Furthermore, the oxidant is selected from at least one of oxygen-containing gas and hydrogen peroxide, and can be any one or more of the above. The oxygen-containing gas is selected from at least one of air and oxygen-enriched gas, and can be any one or a mixture of two of the above. Specifically, oxygen-enriched gas refers to gas with an oxygen volume fraction of 21%-90%. The amount of oxidant used is not limited, as long as it can promote the reaction to proceed fully.

[0058] In some embodiments of this disclosure, when the mass fraction of iron in the cobalt intermediate is less than 0.5%, ferrous sulfate is added to participate in the neutral leaching reaction. The amount of ferrous sulfate added is controlled so that the mass ratio of ferrous sulfate added to the amount of cobalt metal in the cobalt intermediate is (4-6):100, such as 4:100, 5:100, 6:100, etc. When the content of divalent iron ions in the cobalt intermediate is low, an appropriate amount of ferrous sulfate is added to participate in the reaction.

[0059] In some embodiments of this disclosure, such as Figure 2 As shown, in the neutral leaching process, multiple reactors are connected in series. Cobalt intermediate slurry, sulfuric acid and oxidant are added to the first reactor, and cobalt intermediate slurry is added to the middle reactor. The pH value of leaching is controlled at 5.0-5.4, and the residence time in each reactor is 1.5h-1.6h. When the mass fraction of iron in the cobalt intermediate is less than 0.5%, ferrous sulfate is added to the first reactor.

[0060] Specifically, the leaching apparatus for neutral leaching can have seven leaching tanks (e.g., Figure 2The first leaching tank can be referred to as a neutral leaching oxidation tank, and the other leaching tanks are referred to as neutral leaching tanks. Filtration separation is performed after the output of the material in the last leaching tank.

[0061] In other embodiments of the present disclosure, the neutral leaching can also be performed in a single reaction kettle, not limited to Figure 2 The device.

[0062] S2, reduction acid leaching

[0063] The neutral leaching residue is subjected to reduction acid leaching to obtain an acid leaching residue and an acid leaching solution. Through reduction acid leaching, the iron in the neutral leaching residue is reduced to divalent iron ions again, and the residual high-valence cobalt is reduced to divalent cobalt ions, achieving efficient leaching of the neutral residue.

[0064] In actual operation, the process of reduction acid leaching includes: mixing and slurrying the neutral leaching residue with water, the mass ratio of the neutral leaching residue to water being 1:(3-5), then mixing with sulfuric acid and a reducing agent, the leaching temperature being 60-80°C, and the leaching time being greater than 2h, so as to fully react and leach cobalt. Specifically, the mass ratio of the neutral leaching residue to water can be 1:3, 1:4, 1:5, etc.; the leaching temperature can be 60°C, 65°C, 70°C, 75°C, 80°C, etc.; and the leaching time can be 2.5h, 3.0h, 4.0h, 5.0h, 6.0h, etc.

[0065] In a preferred embodiment of the present disclosure, the leaching temperature of the reduction acid leaching is 65-75°C, the leaching time is 3-4h, and the leaching pH value is 1.5-2.0. By optimizing the conditions of the reduction acid leaching, the leaching rate of cobalt is improved. The leaching pH value is adjusted by the amount of sulfuric acid added, and the leaching pH value can be 1.5, 1.8, 2.0, etc.

[0066] In some embodiments of the present disclosure, the reducing agent is selected from at least one of sulfur dioxide, ammonium pyrosulfite and hydrogen peroxide, and can be any one or several of the above, and is preferably sulfur dioxide. Using sulfur dioxide as a reducing agent raw material is easy to obtain, can avoid the introduction of other impurity ions, reduces the use amount of sulfuric acid, and solves the problems of high production cost and low reduction efficiency caused by the introduction of other reducing agents.

[0067] Further, the sulfur dioxide can be provided by an acid-making system, as shown in Figure 3 High-purity sulfur dioxide generated in the acid-making system is dried and compressed, and then delivered to the reduction acid leaching reaction kettle. Specifically, the sulfur dioxide output by the acid-making system enters a sulfur dioxide storage tank, and then is dried in a drying tower. The pipeline is directly connected to the reduction acid leaching process. A sulfur dioxide compressor is started to maintain a positive pressure in the pipeline. The high-purity and dry sulfur dioxide continuously enters the reduction acid leaching reaction kettle.

[0068] Furthermore, the amount of sulfur dioxide used is calculated based on the volume of the slurry, and the amount of sulfur dioxide used is 0.1-1 Nm³. 3 / m 3 To ensure the reduction reaction proceeds fully, the amount of sulfur dioxide used can be 0.1 Nm³. 3 / m 3 0.5Nm 3 / m 3 1.0Nm 3 / m 3 wait.

[0069] S3, high acid leaching

[0070] The acid leaching residue is subjected to high acid leaching, with the pH value controlled to be less than 0.5. Through high acid leaching, cobalt metal in the acid leaching residue can be further leached out to obtain a cobalt-containing high acid leaching solution. The high acid leaching solution is then returned to the neutral leaching stage.

[0071] In some embodiments of this disclosure, the high-acid leaching process includes: mixing and reacting the acid leaching residue with hydrogen peroxide and sulfuric acid, controlling the reaction temperature at 85℃-95℃, the reaction pH at 0.25-0.45, and the leaching time at 4h-5h. By further optimizing the high-acid leaching conditions, cobalt is leached more thoroughly. The amount of hydrogen peroxide added is based on the theoretical dosage: theoretical hydrogen peroxide dosage = 1.3 * (34 * cobalt content in the residue * 8000 kg) / (2 * 55.85) ≈ 3200 * cobalt content in the residue (kg).

[0072] Specifically, the reaction temperature can be 85℃, 90℃, 95℃, etc., the reaction pH value can be 0.25, 0.30, 0.35, 0.40, 0.45, etc., the leaching pH value can be 0.25, 0.30, 0.35, 0.40, 0.45, etc., and the leaching time can be 4.0h, 4.5h, 5.0h, etc.

[0073] S4, copper removal

[0074] The acid leaching solution produced during the reduction leaching process is mixed with iron powder to carry out a copper removal reaction, resulting in a copper-removed solution, which then enters the iron removal process. Iron powder is used as a reducing agent to displace copper ions from the acid leaching solution, yielding sponge copper.

[0075] In some embodiments of this disclosure, by adjusting the amount of iron powder, the concentration of copper ions in the solution after copper removal is made to be 50 mg / L-200 mg / L. A small amount of copper ions can act as an iron catalyst, and most of the ferric iron is reduced during the two-stage reducing acid leaching process. The iron exists in the solution as ferrous ions, and the following reaction occurs:

[0076] SO₂ + 2H₂O + 2Fe 3+ =2Fe2+ +SO4 2- +4H + ;

[0077] During the copper removal stage, a small amount of ferric iron is present, and the following reaction occurs:

[0078] 2Fe 3+ +Fe==3Fe 2+ ;

[0079] Cu 2+ +Fe==Cu+Fe 2+ ;

[0080] Specifically, the concentration of copper ions in the solution after copper removal can be controlled at 50 mg / L, 100 mg / L, 150 mg / L, 200 mg / L, etc. Iron dosage (kg) = feed solution volume (m³) 3 * Copper concentration in the second stage leaching solution (g / l) * 55.85 / 64 * 1.1, where 1.1 is a coefficient.

[0081] S5, Iron Removal

[0082] The iron removal process includes: mixing the copper-removed liquid with oxygen-containing gas, a neutralizing agent, and a nucleating reagent, controlling the reaction pH to 3.0-3.5, and maintaining the Fe content in the system during the process. 3+ The concentration is less than 1 g / L. During the reaction, oxygen-containing gas oxidizes the ferrous ions in the solution, causing them to precipitate. The nucleating reagent acts as a seed crystal, greatly improving the growth rate of goethite and the filtration performance of iron slag (when Fe...). 3+ When the concentration of Fe is greater than 1 g / L, Fe(OH)3 colloid is easily generated. This colloid has a large particle size, is difficult to filter, and carries away a lot of valuable metals. This solves the problems of large slag volume, poor filtration performance and high energy consumption in the existing iron removal process, and can shorten the process flow of cobalt recovery in the overall process.

[0083] Specifically, the pH value of the reaction can be controlled to be 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, etc., and the Fe in the system... 3+ The concentration can be 0.1g / L, 0.3g / L, 0.5g / L, 0.8g / L, 0.9g / L, etc.

[0084] In some embodiments of this disclosure, the oxygen-containing gas is selected from at least one of air and oxygen-enriched gas, and can be any one or a mixture of two of them, wherein the oxygen-enriched gas refers to an oxygen volume fraction of 21%-90%. Using air / oxygen-enriched air instead of hydrogen peroxide to oxidize ferrous ions reduces production costs. The flow rate of the oxygen-containing gas is adjusted according to the solution volume, and the flow rate is 0.1 NM. 3 / m 3 -1.0NM3 / m 3 In other words, 1m 3 The volume of the copper-removed liquid corresponds to a flow rate of 0.1 NM of oxygen-containing gas. 3 0.3NM 3 0.5NM 3 0.8NM 3 1.0NM 3 In actual operation, the flow rate of oxygen-containing gas is adjusted according to the concentration of ferrous ions to control the oxidation rate of ferrous ions and maintain the concentration of trivalent ions in the system at less than 1 g / L.

[0085] In some embodiments of this disclosure, the neutralizing agent is selected from at least one of cobalt carbonate and cobalt intermediates, and can be any one or a mixture of two of the above. A nickel-cobalt-based neutralizing agent is used to adjust the leaching pH to meet requirements. The iron precipitation process is one in which acidity continuously increases; using a neutralizing agent also reduces the amount of sulfuric acid used in the main process, thus lowering production costs.

[0086] In some embodiments of this disclosure, the nucleating agent is calcium carbonate. By controlling the amount of the nucleating agent, the concentration of the generated calcium sulfate crystals is made to be 1 g / m³. 3 -100g / m 3 (e.g., 1g / m) 3 10g / m 3 30g / m 3 50g / m 3 80g / m 3 100g / m 3 (etc.), using calcium sulfate crystals as nuclei to accelerate the nucleation rate of goethite, resulting in iron slag with good filtration performance and high iron content.

[0087] Furthermore, in the iron removal process, the reaction temperature is controlled at 80℃-90℃, and the reaction time is 2h-3h. At this reaction temperature, iron can be further removed. Specifically, the reaction temperature can be 80℃, 85℃, 90℃, etc., and the reaction time can be 2.0h, 2.5h, 3.0h, etc.

[0088] In some embodiments of this disclosure, the iron removal process can be continuous, such as... Figure 4 As shown, it includes a first reaction tank, a second reaction tank, a third reaction tank, and a fourth reaction tank connected in series (i.e., Figure 4 The cobalt iron removal process consists of four tanks: A (cobalt iron removal tank A), B (cobalt iron removal tank B), C (cobalt iron removal tank C), and D (cobalt iron removal tank D). In the first reaction tank, the copper-removed liquid, oxygen-containing gas (such as air or oxygen), and a neutralizing agent are added. In the second reaction tank, the copper-removed liquid, neutralizing agent, and nucleating reagent are added. In the third reaction tank, oxygen-containing gas is added. The material output from the fourth reaction tank undergoes solid-liquid separation. The resulting liquid material contains Fe... 3+When the concentration is greater than 1 g / L, it is returned to the first reaction tank, and the resulting liquid material contains Fe. 3+ Concentrations less than 1 g / L will not be returned. The pH of each reaction tank is controlled at 3.0-3.5, Fe... 3+ The concentration is less than 1 g / L.

[0089] In some embodiments of this disclosure, the residence time of the first reaction tank, the second reaction tank, the third reaction tank, and the fourth reaction tank is 1.5h-2.5h, so that the total reaction time meets the requirements.

[0090] The features and performance of this disclosure will be further described in detail below with reference to embodiments.

[0091] It should be noted that, by mass fraction, the composition of the cobalt intermediates processed in the following examples is as follows: Co 30-40%, Al and Ca ≤0.5%, H2O ≤15%, Mg ≤5%.

[0092] Example 1

[0093] This embodiment provides a method for recovering cobalt intermediates, including the following steps:

[0094] (1) Neutral leaching

[0095] A cobalt intermediate slurry was prepared by mixing cobalt intermediates with water, with a cobalt intermediate mass fraction of 13%. When the iron content in the cobalt intermediates was greater than 0.5%, the cobalt intermediate slurry was fed into the reactor without adding ferrous sulfate, and the final pH value of the reaction was controlled to be 5.0. Figure 2 The apparatus for leaching consists of seven reaction tanks, denoted as AG. Tank A is the oxidation tank, where air, cobalt intermediate slurry, ferrous sulfate, and sulfuric acid are added. Tank D is where cobalt intermediate slurry is added to adjust the pH value. The material output from tank G is then separated by pressure filtration. The pH values ​​are as follows: Tank A: 1.0-1.5; Tank B: 1.5-2.0; Tank C: 2.0-2.5; Tank D: 3.5-4.0; Tank E: 4.0-5.0; Tank F: 5.0-5.4; Tank G: 5.0-5.4. The temperature of each reaction tank is controlled at 60℃, and the slurry flow rate in tank A is 27 m³ / s. 3 / h, sulfuric acid flow rate 2.2m 3 The residence time in each of the five tanks is 1.5-1.6 hours. Neutral leaching residue and post-leaching liquid are produced; the post-leaching liquid proceeds to the next process.

[0096] According to the test, the cobalt leaching rate after neutral leaching in this embodiment was 80%, and the cobalt content in the neutral leaching residue was 22% (mass fraction, the same below).

[0097] (2) Reduction acid leaching

[0098] Neutral leaching residue and water were slurried at a mass ratio of 1:3, stirred, and concentrated sulfuric acid was added. The temperature was raised to 70°C, and then sulfur dioxide was introduced for reduction leaching. The pH value was adjusted to 2.0 (based on online pH monitoring and on-site manual pH testing). The reaction time was 4 hours, yielding acid leaching residue and acid leaching solution. Figure 3 The leaching process is carried out in a specific manner.

[0099] Tests showed that the acid leaching residue in this embodiment contained 3% cobalt.

[0100] (3) High acid leaching

[0101] In step (2), the acid leaching residue is mixed with hydrogen peroxide and concentrated sulfuric acid for high acid leaching. The reaction temperature is controlled at 90°C and the pH value is controlled at 0.2. The molar ratio of the amount of hydrogen peroxide added to the cobalt metal content in the acid leaching residue is 1:2. The cobalt metal in the acid leaching residue is further leached to obtain a cobalt-containing leachate that can be reused in the leaching system.

[0102] Tests showed that the residue after high acid leaching contained 0.3% cobalt.

[0103] (4) Copper removal

[0104] In step (2), the acid leaching solution is mixed with iron powder to reduce copper ions in the solution and obtain sponge copper. After copper removal, it enters the continuous iron removal reaction tank. The amount of iron powder to be added is calculated based on the concentration of copper ions in the acid leaching solution so that the concentration of copper ions in the solution after copper removal is 50 mg / L.

[0105] (5) Iron removal

[0106] use Figure 4 The apparatus in the middle performs continuous iron removal. The copper-removed liquid is mixed with air, cobalt carbonate, and calcium carbonate for reaction. The amount of cobalt carbonate is adjusted to control the pH value of the reaction at 3.0-3.5. During the process, the Fe content in the system is maintained. 3+ The concentration is less than 1 g / L. The air flow rate is adjusted according to the solution volume, and the air flow rate is controlled at 0.5 NM. 3 / m 3 The reaction temperature is controlled at 80-90℃. The concentration of calcium sulfate crystals produced is adjusted to 50 g / m³ by adjusting the amount of calcium sulfate used. 3 .

[0107] The first reaction tank contains the copper-removed liquid, air, and cobalt carbonate. The second reaction tank contains air, cobalt carbonate, and calcium carbonate. The third reaction tank contains air. The material output from the fourth reaction tank undergoes solid-liquid separation. The resulting liquid contains Fe. 3+ When the concentration is greater than 1 g / L, it is returned to the first reaction tank, and the resulting liquid material contains Fe. 3+ If the concentration is less than 1 g / L, it will not be returned. The air flow rate from the first reaction tank to the third reaction tank is 1 NM.3 / m 3 0.8NM 3 / m 3 0.5NM 3 / m 3 The pH values ​​of the first to the third reaction tanks were 3.0, 3.2, and 3.5, respectively, and the temperature of all three reaction tanks was 85℃. Fe 3+ The concentration was less than 1 g / L. The residence time in the first, second, third, and fourth reaction tanks was 2 hours.

[0108] Tests showed that the iron ion concentration in the liquid after iron and aluminum removal was 3 g / L, and the iron content in the iron-aluminum slag was 40% (mass fraction, the same below).

[0109] Example 2

[0110] This embodiment provides a method for recovering cobalt intermediates, including the following steps:

[0111] (1) A cobalt intermediate slurry is obtained by mixing cobalt intermediates with water to form a slurry, wherein the mass fraction of cobalt intermediates in the slurry is 13%. When the iron content in the cobalt intermediate is less than 0.5%, the cobalt intermediate slurry is fed into a reactor. In the reactor, the cobalt intermediate slurry, concentrated sulfuric acid (mass fraction 98%, the same below), and ferrous sulfate are mixed. The mass ratio of ferrous sulfate added to the cobalt metal content in the cobalt intermediate is 5:100, and the pH value at the final reaction endpoint is controlled to be 5.0. Figure 2 The apparatus for leaching consists of seven reaction tanks, denoted as AG. Tank A is the oxidation tank, where air, cobalt intermediate slurry, ferrous sulfate, and sulfuric acid are added. Tank D is where cobalt intermediate slurry is added to adjust the pH value. The material output from tank G is then separated by pressure filtration. The pH values ​​are as follows: Tank A: 1.0-1.5; Tank B: 1.5-2.0; Tank C: 2.0-2.5; Tank D: 3.5-4.0; Tank E: 4.0-5.0; Tank F: 5.0-5.4; Tank G: 5.0-5.4. The temperature of each reaction tank is controlled at 60℃, and the slurry flow rate in tank A is 27 m³ / s. 3 / h, sulfuric acid flow rate 2.2m 3 The residence time in each of the five tanks is 1.5-1.6 hours. Neutral leaching residue and post-leaching liquid are produced; the post-leaching liquid proceeds to the next process.

[0112] According to the test, the cobalt leaching rate after neutral leaching in this embodiment was 88%, and the cobalt content in the neutral leaching residue was 20%.

[0113] (2) Reduction acid leaching

[0114] Neutral leaching residue and water were slurried at a mass ratio of 1:4, stirred, and concentrated sulfuric acid was added. The temperature was raised to 70°C, and then sulfur dioxide was introduced to carry out reductive leaching. The pH value was adjusted to 1.5, and the reaction time was 4 hours, yielding acid leaching residue and acid leaching solution. Figure 3 The leaching process is carried out in a specific manner.

[0115] Tests showed that the acid leaching residue in this embodiment contained 2.5% cobalt.

[0116] (3) High acid leaching

[0117] In step (2), the acid leaching residue is mixed with hydrogen peroxide and concentrated sulfuric acid for high acid leaching. The reaction temperature is controlled at 90°C and the pH value is controlled at 0.3. The molar ratio of the amount of hydrogen peroxide added to the cobalt metal content in the acid leaching residue is 1:2. The cobalt metal in the acid leaching residue is further leached to obtain a cobalt-containing leachate that can be reused in the leaching system.

[0118] Tests showed that the residue after high acid leaching contained 0.4% cobalt.

[0119] (4) Copper removal

[0120] In step (2), the acid leaching solution is mixed with iron powder to reduce copper ions in the solution and obtain sponge copper. After copper removal, it enters the continuous iron removal reaction tank. The amount of iron powder to be added is calculated based on the concentration of copper ions in the acid leaching solution so that the concentration of copper ions in the solution after copper removal is 100 mg / L.

[0121] (5) Iron removal

[0122] use Figure 4 The apparatus in the middle performs continuous iron removal. The copper-removed liquid is mixed with air, cobalt carbonate, and calcium carbonate for reaction. The amount of cobalt carbonate is adjusted to control the pH value of the reaction at 3.0-3.5. During the process, the Fe content in the system is maintained. 3+ The concentration is less than 1 g / L. The air flow rate is adjusted according to the solution volume, and the air flow rate is controlled at 0.5 NM. 3 / m 3 The reaction temperature is controlled at 80-90℃. The concentration of calcium sulfate crystals produced is adjusted to 50 g / m³ by adjusting the amount of calcium sulfate used. 3 .

[0123] The first reaction tank contains the copper-removed liquid, air, and cobalt carbonate. The second reaction tank contains air, cobalt carbonate, and calcium carbonate. The third reaction tank contains air. The material output from the fourth reaction tank undergoes solid-liquid separation. The resulting liquid contains Fe. 3+ When the concentration is greater than 1 g / L, it is returned to the first reaction tank, and the resulting liquid material contains Fe. 3+ If the concentration is less than 1 g / L, it will not be returned. The air flow rate from the first reaction tank to the third reaction tank is 1 NM. 3 / m3 0.8NM 3 / m 3 0.5NM 3 / m 3 The pH values ​​of the first to the third reaction tanks were 3.0, 3.2, and 3.5, respectively, and the temperature of all three reaction tanks was 85℃. Fe 3+ The concentration was less than 1 g / L. The residence time in the first, second, third, and fourth reaction tanks was 2 hours.

[0124] Tests showed that the iron ion concentration in the liquid after iron and aluminum removal was 2 g / L, and the iron content in the iron-aluminum slag was 42%.

[0125] Example 3

[0126] (1) A cobalt intermediate slurry is obtained by mixing cobalt intermediates with water to form a slurry, wherein the mass fraction of cobalt intermediates in the slurry is 15%. When the iron content in the cobalt intermediate is less than 0.5%, the cobalt intermediate slurry is fed into a reactor. In the reactor, the cobalt intermediate slurry, concentrated sulfuric acid (mass fraction 98%, the same below), and ferrous sulfate are mixed. The mass ratio of ferrous sulfate added to the cobalt metal content in the cobalt intermediate is 5:100, and the pH value at the final reaction endpoint is controlled to be 5.4. Figure 2 The apparatus for leaching consists of seven reaction tanks, denoted as AG. Tank A is the oxidation tank, where air, cobalt intermediate slurry, ferrous sulfate, and sulfuric acid are added. Tank D is where cobalt intermediate slurry is added to adjust the pH value. The material output from tank G is then separated by pressure filtration. The pH values ​​are as follows: Tank A: 1.0-1.5; Tank B: 1.5-2.0; Tank C: 2.0-2.5; Tank D: 3.5-4.0; Tank E: 4.0-5.0; Tank F: 5.0-5.4; Tank G: 5.0-5.4. The temperature of each reaction tank is controlled at 60℃, and the slurry flow rate in tank A is 27 m³ / s. 3 / h, sulfuric acid flow rate 2.2m 3 The residence time in each of the five tanks is 1.5-1.6 hours. Neutral leaching residue and post-leaching liquid are produced; the post-leaching liquid proceeds to the next process.

[0127] Tests showed that the cobalt leaching rate after neutral leaching in this embodiment was 90%, and the cobalt content in the neutral leaching residue was 18%.

[0128] (2) Reduction acid leaching

[0129] Neutral leaching residue and water were slurried at a mass ratio of 1:5, stirred, and concentrated sulfuric acid was added. The temperature was raised to 70°C, and then sulfur dioxide was introduced to carry out reduction leaching. The pH value was adjusted to 1.0, and the reaction time was 4 hours, yielding acid leaching residue and acid leaching solution. Figure 3 The leaching process is carried out in a specific manner.

[0130] Tests showed that the acid leaching residue in this embodiment contained 2.0% cobalt.

[0131] (3) High acid leaching

[0132] In step (2), the acid leaching residue is mixed with hydrogen peroxide and concentrated sulfuric acid for high acid leaching. The reaction temperature is controlled at 90°C and the pH value is controlled at 0.4. The molar ratio of the amount of hydrogen peroxide added to the cobalt metal content in the acid leaching residue is 1:2. The cobalt metal in the acid leaching residue is further leached to obtain a cobalt-containing leachate that can be reused in the leaching system.

[0133] Tests showed that the residue after high acid leaching contained 0.3% cobalt.

[0134] (4) Copper removal

[0135] In step (2), the acid leaching solution is mixed with iron powder to reduce copper ions in the solution and obtain sponge copper. After copper removal, it enters the continuous iron removal reaction tank. The amount of iron powder to be added is calculated based on the concentration of copper ions in the acid leaching solution so that the concentration of copper ions in the solution after copper removal is 200 mg / L.

[0136] (5) Iron removal

[0137] use Figure 4 The apparatus in the middle performs continuous iron removal. The copper-removed liquid is mixed with air, cobalt carbonate, and calcium carbonate for reaction. The amount of cobalt carbonate is adjusted to control the pH value of the reaction at 3.0-3.5. During the process, the Fe content in the system is maintained. 3+ The concentration is less than 1 g / L. The air flow rate is adjusted according to the solution volume, and the air flow rate is controlled at 0.5 NM. 3 / m 3 The reaction temperature is controlled at 80-90℃. The concentration of calcium sulfate crystals produced is adjusted to 50 g / m³ by adjusting the amount of calcium sulfate used. 3 .

[0138] The first reaction tank contains the copper-removed liquid, air, and cobalt carbonate. The second reaction tank contains air, cobalt carbonate, and calcium carbonate. The third reaction tank contains air. The material output from the fourth reaction tank undergoes solid-liquid separation. The resulting liquid contains Fe. 3+ When the concentration is greater than 1 g / L, it is returned to the first reaction tank, and the resulting liquid material contains Fe. 3+ If the concentration is less than 1 g / L, it will not be returned. The air flow rate from the first reaction tank to the third reaction tank is 1 NM. 3 / m 3 0.8NM 3 / m 3 0.5NM 3 / m 3 The pH values ​​of the first to the third reaction tanks were 3.0, 3.2, and 3.5, respectively, and the temperature of all three reaction tanks was 85℃. Fe3+ The concentration was less than 1 g / L. The residence time in the first, second, third, and fourth reaction tanks was 2 hours.

[0139] Tests showed that the iron ion concentration in the liquid after iron and aluminum removal was 1 g / L, and the iron content in the iron-aluminum slag was 45%.

[0140] Example 4

[0141] The only difference from Example 1 is that when the iron content of the neutral leaching cobalt intermediate is less than 0.5%, a neutral leaching stage is supplemented with ferrous sulfate accounting for 5% of the cobalt metal content of the cobalt intermediate.

[0142] The results show that this embodiment improves the leaching rate of cobalt metal, increasing it from 80% to 88%.

[0143] Example 5

[0144] The only difference from Example 1 is that the concentration of the neutral leaching pulp is increased (the mass fraction of cobalt intermediate in the cobalt intermediate pulp is 15%), and the final pH value is adjusted to 5.4.

[0145] The results showed that this embodiment reduced the cobalt content in the neutral leaching residue from 22% to 18%, and increasing the pulp concentration was beneficial to improving the leaching rate.

[0146] Examples 6-8

[0147] The only difference from Example 1 is that in the reducing acid leaching, the solid-liquid ratio of the neutral leaching residue is adjusted from 1:3 to 1:5, and the pH value of the reducing acid leaching in Examples 6-8 is adjusted to 1.0, 1.5, and 2.0, respectively.

[0148] The results showed that Examples 6-8 improved the leaching rate of cobalt in the two-stage reduction acid leaching, with cobalt contents in the acid leaching residues of 2.0%, 2.5%, and 3.0%, respectively.

[0149] Examples 9-10

[0150] The only difference from Example 1 is that the pH value of the operation was adjusted to 0.4 and 0.3 respectively in the high acid leaching process to improve the leaching rate of cobalt.

[0151] The results showed that the cobalt content of the leaching residues obtained after high acid leaching in Examples 9 and 10 was 0.5% and 0.4%, respectively.

[0152] Examples 11-12

[0153] The only difference from Example 1 is that different copper ion concentrations are maintained in the copper removal reaction. In Examples 11-12, the copper ion concentrations in the copper removal solution are controlled to be 100 mg / L and 200 mg / L, respectively.

[0154] The results showed that the iron ion concentrations in the liquid after iron and aluminum removal in Examples 11-12 were 2 g / L and 1 g / L, respectively, and the iron content in the iron and aluminum slag was 42% and 45%, respectively.

[0155] Industrial applicability

[0156] This invention discloses a three-stage leaching process consisting of neutral leaching, reducing acid leaching, and high-acid leaching. This process maximizes the recovery of cobalt from cobalt intermediates, thereby improving the recovery rate of valuable metals. By employing a continuous iron removal process, using cobalt carbonate or cobalt intermediates as a neutralizing agent to adjust the pH value, and using calcium sulfate generated from calcium carbonate as a seed crystal, the crystallization rate of iron removal is improved, and the filtration performance of the slag is enhanced. The overall process is easy to operate and has excellent industrial applicability.

Claims

1. A method for recovering a cobalt intermediate, characterized by, The application relates to a method for leaching cobalt from cobalt intermediate. The cobalt intermediate slurry and sulfuric acid are mixed to carry out neutral leaching under oxidation conditions, the pH value of the leaching is controlled to be 5.0-5.4, and neutral leaching residue and post-leaching liquid are obtained; The neutral leaching residue is subjected to reduction acid leaching to obtain acid leaching residue and acid leaching liquid; The acid leaching residue is subjected to high-acid leaching to obtain high-acid leaching liquid; The high-acid leaching liquid is returned to the neutral leaching stage; The process of the neutral leaching comprises the following steps: the cobalt intermediate is mixed with water to prepare cobalt intermediate slurry, the mass fraction of the cobalt intermediate in the cobalt intermediate slurry is 13%-15%, the cobalt intermediate slurry is mixed with sulfuric acid and an oxidant to carry out reaction, the leaching temperature is controlled to be 50 DEG C-70 DEG C, and the reaction time is 1.5 h-1.6 h; when the mass fraction of iron in the cobalt intermediate is less than 0.5%, ferrous sulfate is supplemented to participate in the neutral leaching reaction, and the mass ratio of the ferrous sulfate supplement amount to the cobalt metal amount in the cobalt intermediate is (4-6):100; The process of the reduction acid leaching comprises the following steps: the neutral leaching residue is mixed with water to prepare slurry, and then mixed with sulfuric acid and a reducing agent, the leaching temperature is 60 DEG C-80 DEG C, the leaching time is greater than 2 h, and the leaching pH value is 1.5-2.0; the mass ratio of the neutral leaching residue to water is 1:(3-5); The process of the high-acid leaching comprises the following steps: the acid leaching residue is mixed with hydrogen peroxide and sulfuric acid to carry out reaction, the reaction temperature is controlled to be 85 DEG C-95 DEG C, the reaction pH value is 0.25-0.45, and the leaching time is 4 h-5 h.

2. The recycling method according to claim 1, characterized in that, In the process of the neutral leaching, a plurality of reaction kettles are connected in series, the cobalt intermediate slurry, sulfuric acid and an oxidant are added into the first reaction kettle, the cobalt intermediate slurry is added into the middle reaction kettles, the leaching pH value is controlled to be 5.0-5.4, and the residence time in each reaction kettle is 1.5 h-1.6 h; When the mass fraction of iron in the cobalt intermediate is less than 0.5%, ferrous sulfate is supplemented into the first reaction kettle.

3. The recycling method of claim 1, wherein, The oxidant is selected from at least one of oxygen-containing gas and hydrogen peroxide.

4. The recycling method according to claim 3, characterized in that, The oxygen-containing gas is selected from at least one of air and oxygen-enriched gas, and the oxygen volume fraction in the oxygen-enriched gas is 21%-90%.

5. The recycling method of claim 1, wherein, The leaching temperature of the reduction acid leaching is 65 DEG C-75 DEG C, and the leaching time is 3 h-4 h.

6. The recycling method of claim 1, wherein, The reducing agent is selected from at least one of sulfur dioxide, ammonium pyrosulfite and hydrogen peroxide.

7. The recycling method of claim 1, wherein, The reducing agent is sulfur dioxide.

8. The recycling method according to claim 7, characterized in that, The amount of sulfur dioxide is 0.1-1 Nm 3 / m 3 .

9. The recycling method of claim 7, wherein, The sulfur dioxide generated in an acid-making system is dried and compressed, and then introduced into the reaction kettle of the reduction acid leaching.

10. The recycling method of claim 1, wherein, The acid leaching liquid generated in the process of the reduction acid leaching is mixed with iron powder to carry out copper removal reaction, post-copper-removal liquid is obtained, and the post-copper-removal liquid enters an iron removal procedure. The concentration of copper ions in the post-copper-removal liquid is controlled to be 50 mg / L-200 mg / L by adjusting the amount of the iron powder.

11. The recycling method of claim 10, wherein, In the iron removal procedure, the reaction temperature is controlled to be 80 DEG C-90 DEG C, and the reaction time is 1.5 h-3 h.

12. The recycling method of claim 10, wherein, The process of the iron removing procedure comprises mixing and reacting the copper-removed solution with oxygen-containing gas, neutralizing agent and nucleating agent, controlling the pH value of the reaction to be 3.0-3.5, and keeping the concentration of Fe 3+ in the system less than 1 g / L during the process.

13. The recycling method of claim 12, wherein, The oxygen-containing gas is selected from at least one of air and oxygen-enriched gas, and the oxygen volume fraction in the oxygen-enriched gas is 21%-90%.

14. The recycling method of claim 12, wherein, The neutralizing agent is selected from at least one of cobalt carbonate and cobalt intermediate.

15. The recycling method of claim 14, wherein, The flow rate of the oxygen-containing gas is 0.1 NM 3 / m 3 -1.0 NM 3 / m 3 .

16. The recycling method of claim 12, wherein, The nucleation agent is calcium carbonate.

17. The recycling method of claim 12, wherein, ​ 18. The recycling method of claim 17, wherein, By controlling the amount of the nucleating agent, the concentration of the calcium sulfate crystals generated is 1 g / m 3 - 100 g / m 3 .

19. The recycling method of claim 12, wherein, The iron removing process is continuous iron removing, which comprises first reaction tank, second reaction tank, third reaction tank and fourth reaction tank connected in series, the first reaction tank is added with the copper-removed solution, the oxygen-containing gas and the neutralizing agent, the second reaction tank is added with the copper-removed solution, the neutralizing agent and the nucleation agent, the third reaction tank is added with the oxygen-containing gas, and the material output from the fourth reaction tank is subjected to solid-liquid separation, and the liquid material obtained is returned to the first reaction tank when the Fe 3+ concentration is greater than 1 g / L.

20. The recycling method of claim 19, wherein, The residence time of the first reaction tank, the second reaction tank, the third reaction tank and the fourth reaction tank is 1.5h-2.5h. The residence time of the first reaction tank, the second reaction tank, the third reaction tank and the fourth reaction tank is 1.5h-2.5h.

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