Method for recovering scandium from cobalt nickel hydroxide intermediate product

Abstract

The invention relates to the technical field of scandium resource recovery, in particular to a method for recovering scandium from a cobalt nickel hydroxide intermediate product. The method for recovering scandium from the cobalt-nickel hydroxide intermediate product comprises the following steps: S1, leaching the cobalt-nickel hydroxide intermediate product, a reducing agent and a sulfuric acid solution to obtain a leachate; s2, carrying out scandium precipitation treatment on the leachate and a precipitant to obtain a first scandium enrichment and a crude nickel sulfate solution; dissolving the first scandium enrichment in sulfuric acid to obtain a scandium sulfate solution; s3, the scandium sulfate solution and a precipitant are subjected to precipitation double salt treatment, and a second scandium enriched product is obtained; calcining the second scandium enrichment to obtain a third scandium enrichment; s4, dissolving the third scandium concentrate with hydrochloric acid to obtain a scandium chloride solution; the scandium chloride solution is subjected to scandium precipitation treatment through oxalic acid to obtain scandium-containing precipitates; and calcining the scandium-containing precipitate to obtain scandium oxide. According to the method, the loss rate of cobalt, nickel and manganese is low, high-purity scandium oxide can be recycled, an extracting agent does not need to be used, safety and environment friendliness are achieved, and meanwhile the high scandium recycling rate is guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of scandium resource recovery, and in particular to a method for recovering scandium from a cobalt-nickel hydroxide intermediate. Background Art

[0002] Scandium (Sc), as a rare earth element, is widely distributed in the earth's crust, but its content is very small, which makes it complicated to extract scandium from ores with complex composition and extremely low content. Due to its special physical and chemical properties, scandium has broad development prospects in the fields of fighter jets, aerospace, solid oxide fuel cells (SOFCs), metal halide lamps, etc.

[0003] The acquisition of scandium usually relies on the by-products of other metals, mainly from waste liquid, waste and slag in the production process of uranium, nickel, aluminum, vanadium, tungsten, titanium and some rare earth elements, so the market availability of scandium is low and the cost is high. In addition, scandium is also found in laterite nickel ores in most regions. Due to the low grade and dispersed distribution of scandium in laterite nickel ores, most of the scandium enters the intermediate product of nickel cobalt hydroxide (MHP) during the smelting process. The efficient enrichment and recovery technology of scandium in laterite nickel ores has problems such as complex recovery process and high recovery cost.

[0004] The content of cobalt, nickel, iron, manganese and other elements in laterite nickel ore is relatively high, while the content of scandium is much lower than that of these elements, which interferes with the recovery of scandium. When using chemical precipitation to recover scandium, it will result in high losses of cobalt, nickel and manganese, and the purity of the scandium oxide finally obtained is not high. In addition to the precipitation method to recover scandium, it is also common to use extraction method to extract scandium from the leachate, but the recovery cost is often high and there is certain pollution to the environment.

[0005] In view of this, this invention is proposed. Summary of the invention

[0006] The object of the present invention is to provide a method for recovering scandium from a cobalt-nickel hydroxide intermediate, which has a low loss rate of cobalt, nickel and manganese and can recover high-purity scandium oxide without using an extractant. It is safe and environmentally friendly while ensuring a high recovery rate of scandium.

[0007] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0008] The present invention provides a method for recovering scandium from a cobalt-nickel hydroxide intermediate, comprising the following steps:

[0009] S1, subjecting the cobalt-nickel hydroxide intermediate, a reducing agent and a sulfuric acid solution to atmospheric pressure reduction leaching to obtain a leachate;

[0010] S2, subjecting the leachate and the first precipitant to a first scandium precipitation treatment to obtain a first scandium-enriched product and a crude nickel sulfate solution; subjecting the first scandium-enriched product and the sulfuric acid solution to a first acid dissolution to obtain a scandium sulfate solution;

[0011] S3, treating the scandium sulfate solution and the second precipitant with a precipitated double salt to obtain a second scandium-enriched product; and calcining the second scandium-enriched product to obtain a third scandium-enriched product;

[0012] S4, subjecting the third scandium-enriched product and hydrochloric acid solution to a second acid dissolution to obtain a scandium chloride solution; subjecting the scandium chloride solution and oxalic acid solution to a second scandium precipitation treatment to obtain a scandium-containing precipitate; and calcining the scandium-containing precipitate to obtain scandium oxide.

[0013] Further, in step S1, the ratio of the molar number of the reducing agent to the total molar number of the cobalt element and the manganese element in the cobalt nickel hydroxide intermediate is 1:(1.4-1.6);

[0014] And / or, the reducing agent includes at least one of sodium pyrosulfite, sulfur oxide, hydrogen peroxide and sodium thiosulfate.

[0015] Further, step S1 includes at least one of the following features (1) to (3);

[0016] (1) The endpoint pH of the atmospheric pressure reduction leaching is 2.0 to 3.0;

[0017] (2) The temperature of the atmospheric pressure reduction leaching is 45 to 75° C.;

[0018] (3) The normal pressure reduction leaching time is 0.5 to 2 hours.

[0019] Further, in step S2, the first precipitant includes sodium sulfite and / or sodium pyrosulfite;

[0020] and / or, the molar ratio of the first precipitant to the scandium element in the leaching solution is 1:(1-1.5). Further, step S2 includes at least one of the following features (1) to (7);

[0021] (1) The endpoint pH of the first scandium precipitation treatment is 3.0 to 4.0;

[0022] (2) The temperature of the first scandium precipitation treatment is 25 to 45° C.;

[0023] (3) The first scandium precipitation treatment time is 0.5 to 3 hours;

[0024] (4) The temperature of the first acid solution is 75 to 95° C.;

[0025] (5) The first acid dissolution time is 0.5 to 1 h;

[0026] (6) The endpoint acidity of the first acid solution is 3 to 5N;

[0027] (7) The concentration of the sulfuric acid solution is 150 to 300 g / L.

[0028] Further, in step S3, the second precipitant includes ammonium sulfate;

[0029] And / or, the molar ratio of the second precipitant to the scandium element in the scandium sulfate solution is 1:(2-2.5).

[0030] Furthermore, in step S3, the scandium sulfate solution and an ammonium source are mixed to obtain a mixed solution; the mixed solution and the second precipitant are subjected to a double salt precipitation treatment to obtain the second scandium enriched product;

[0031] Preferably, the concentration of ammonium in the mixed solution is 0.5 mol / L;

[0032] Preferably, the ammonium source includes one or more of ammonium chloride, ammonium sulfate and ammonium acetate.

[0033] Further, step S3 includes at least one of the following features (1) to (4);

[0034] (1) The temperature of the precipitation double salt treatment is 25 to 90° C.;

[0035] (2) The precipitation double salt treatment time is 0.5 to 1.5 hours;

[0036] (3) The second enriched product is calcined at a temperature of 400 to 700° C.;

[0037] (4) The calcination time of the second enriched product is 1 to 4 hours.

[0038] Further, step S4 includes at least one of the following features (1) to (3);

[0039] (1) The endpoint pH of the second acid solution is 1.0 to 1.3;

[0040] (2) the temperature of the second acid solution is 70 to 90° C.;

[0041] (3) The second acid dissolution time is 1 to 3 hours.

[0042] Further, step S4 includes at least one of the following features (1) to (6);

[0043] (1) The mass percentage of the oxalic acid solution is 10wt% to 30wt%;

[0044] (2) The endpoint pH of the second scandium precipitation treatment is 1.0 to 1.3;

[0045] (3) The temperature of the second scandium precipitation treatment is 70-90° C.;

[0046] (4) The second precipitation scandium treatment time is 1 to 3 hours;

[0047] (5) The calcination temperature of the scandium-containing precipitate is 600-800°C.

[0048] (6) The calcination time of the scandium-containing precipitate is 2 to 3 hours.

[0049] Compared with the prior art, the present invention has the following beneficial effects:

[0050] The method for recovering scandium from a cobalt-nickel hydroxide intermediate provided by the present invention has a low loss rate of cobalt, nickel and manganese, and can recover high-purity scandium oxide, thereby solving the problems of high loss rate of cobalt, nickel and manganese and low purity of scandium oxide obtained by extracting scandium by precipitation method. In addition, the method of the present invention does not require the use of an extractant, is safer and more environmentally friendly, and ensures a high recovery rate of scandium. The production equipment is simple and easily available, and the investment fee and production cost are low. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0052] Figure 1 The figure is a schematic flow chart of the method for recovering scandium from a cobalt-nickel hydroxide intermediate product according to the present invention. DETAILED DESCRIPTION

[0053] The technical scheme of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and specific embodiments, but it will be understood by those skilled in the art that the following described embodiments are part of embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention, and should not be considered as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of the present invention. If specific conditions are not specified in the embodiments, they are carried out according to normal conditions or conditions recommended by the manufacturer. If the manufacturer is not specified in the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0054] The following is a detailed description of a method for recovering scandium from a cobalt-nickel hydroxide intermediate of the present invention.

[0055] See also Figure 1 In some embodiments of the present invention, a method for recovering scandium from a cobalt-nickel hydroxide intermediate is provided, comprising the following steps:

[0056] S1, subjecting the cobalt-nickel hydroxide intermediate, a reducing agent and a sulfuric acid solution to atmospheric pressure reduction leaching to obtain a leachate;

[0057] S2, subjecting the leachate and the first precipitant to a first scandium precipitation treatment to obtain a first scandium enriched product and a crude nickel sulfate solution; subjecting the first scandium enriched product and the sulfuric acid solution to a first acid dissolution to obtain a scandium sulfate solution;

[0058] S3, treating the scandium sulfate solution and the second precipitant with a precipitated double salt to obtain a second scandium enriched product; and calcining the second scandium enriched product to obtain a third scandium enriched product;

[0059] S4, subjecting the third scandium-enriched product and the hydrochloric acid solution to a second acid dissolution to obtain a scandium chloride solution; subjecting the scandium chloride solution and the oxalic acid solution to a second scandium precipitation treatment to obtain a scandium-containing precipitate; and calcining the scandium-containing precipitate to obtain scandium oxide.

[0060] The method for recovering scandium from a cobalt nickel hydroxide (MHP) intermediate provided by the present invention has a low loss rate of cobalt, nickel and manganese, and can recover high-purity scandium oxide, thereby solving the problems of high loss rate of cobalt, nickel and manganese and low purity of scandium oxide obtained by extracting scandium by precipitation method. In addition, the method of the present invention does not require the use of an extractant, is safer and more environmentally friendly, and ensures a high recovery rate of scandium. The production equipment is simple and easy to obtain, and the investment fee and production cost are low.

[0061] The method for recovering scandium from a cobalt-nickel hydroxide intermediate of the present invention comprises the following steps: firstly, the cobalt-nickel hydroxide intermediate is subjected to atmospheric pressure reduction leaching to dissolve cobalt, nickel, manganese and scandium to obtain a leachate; then, the leachate is subjected to a scandium precipitation treatment to separate scandium from cobalt, nickel and manganese to obtain a scandium-enriched product and a solution after separation and recovery of scandium, wherein the solution after separation and recovery of scandium can continue to produce cobalt-nickel-manganese related products; the scandium-enriched product is acid-dissolved with sulfuric acid to dissolve scandium and provide sulfate radicals required for precipitation of complex salts, and the scandium sulfate solution obtained after acid dissolution is subjected to a complex salt precipitation treatment. By using precipitation double salt treatment, scandium can be well separated from other impurities to obtain a second scandium enriched product; the third enriched product obtained after calcining the second scandium enriched product has higher solubility and is easier to dissolve, and subsequent acid dissolution can better control the endpoint pH; then hydrochloric acid acid dissolution can obtain a suitable acid solution to provide conditions for subsequent scandium precipitation; oxalic acid precipitation of scandium can further separate scandium from other impurities to obtain a higher grade scandium-containing precipitate; the scandium-containing precipitate is calcined to obtain scandium oxide with higher purity, and the calcination process mainly removes impurities such as C, S, and N.

[0062] In some embodiments of the present invention, in step S1, the scandium content of the cobalt nickel hydroxide intermediate is 0.5wt% to 0.7wt%, the cobalt content is 2wt% to 4wt%, the nickel content is 30wt% to 40wt%, and the manganese content is 6wt% to 8wt%.

[0063] In some embodiments of the present invention, in step S1, the ratio of the number of moles of the reducing agent to the total number of moles of the cobalt element and the manganese element in the cobalt nickel hydroxide intermediate is 1:(1.4-1.6).

[0064] In some embodiments of the present invention, in step S1, the reducing agent includes at least one of sodium metabisulfite, sulfur oxide, hydrogen peroxide and sodium thiosulfate; preferably sodium metabisulfite.

[0065] In some embodiments of the present invention, in step S1, the molar amount of sodium metabisulfite is the sum of 0.5 times the molar amount of cobalt and 1 times the molar amount of manganese in the cobalt nickel hydroxide intermediate.

[0066] In some embodiments of the present invention, in step S1, the endpoint pH of atmospheric pressure reduction leaching is 2.0-3.0; typically but not limiting, for example, the endpoint pH of atmospheric pressure reduction leaching can be 2.0, 2.2, 2.4, 2.6, 2.8, 3.0 or a range of any two thereof.

[0067] In some embodiments of the present invention, in step S1, the temperature of atmospheric reduction leaching is 45-75°C; typically but not limitatively, for example, the temperature of atmospheric reduction leaching can be 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C or a range of any two thereof.

[0068] In some embodiments of the present invention, in step S1, the time of atmospheric reduction leaching is 0.5 to 2 hours; typically but not limiting, for example, the time of atmospheric reduction leaching can be 0.5 hours, 1 hour, 1.5 hours, 2 hours or a range of any two thereof.

[0069] In some embodiments of the present invention, in step S1, in the leaching solution, Ni 2+ The content is 70~100g / L, Sc 3+ The content is 0.5~3g / L.

[0070] The above conditions are used to carry out atmospheric pressure reduction leaching of the cobalt-nickel hydroxide intermediate product. Under atmospheric pressure conditions, most of the cobalt, nickel, manganese and scandium can be dissolved into the leaching solution, and the scandium in the cobalt-nickel hydroxide intermediate product can be better recovered.

[0071] In some embodiments of the present invention, in step S2, the first precipitating agent includes sodium sulfite and / or sodium pyrosulfite.

[0072] In some embodiments of the present invention, in step S2, the molar ratio of the scandium element in the first precipitant to the scandium element in the leachate is 1:(1-1.5); typically but not limitatively, for example, the molar ratio of the scandium element in the first precipitant to the scandium element in the leachate can be 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5 or a range of any two thereof.

[0073] In some embodiments of the present invention, in step S2, the endpoint pH of the first scandium precipitation treatment is 3.0-4.0; typically but not limiting, for example, the endpoint pH of the first scandium precipitation treatment can be 3.0, 3.2, 3.4, 3.6, 3.8, 4.0 or a range of any two thereof.

[0074] In some embodiments of the present invention, in step S2, the temperature of the first scandium deposition treatment is 25-45°C; typically but not limiting, for example, the temperature of the first scandium deposition treatment can be 25°C, 30°C, 35°C, 40°C, 45°C or a range of any two thereof.

[0075] In some embodiments of the present invention, in step S2, the time of the first scandium precipitation treatment is 0.5 to 3 hours; typically but not limiting, for example, the time of the first scandium precipitation treatment can be 0.5 hours, 1 hour, 2 hours, 3 hours or a range of any two thereof.

[0076] During the first precipitation of scandium, the reaction equation between the first precipitant and scandium is: 3SO3 2- +2Sc 2+ =Sc2(SO3)3; when the temperature rises to above 45°C, the solubility of scandium sulfite (Sc2(SO3)3) increases, causing part of the formed precipitate to dissolve back into the solution, resulting in a lower scandium recovery rate. During the first scandium precipitation treatment, if the endpoint pH is too low, the scandium in the solution will not be completely precipitated, resulting in a low recovery rate. When the endpoint pH>4, the sulfite in the solution is more likely to react with metal ions such as cobalt, nickel, and manganese, reducing the chance of reacting with scandium. When the pH is higher, the acidity in the solution is weakened, and these metal ions may precipitate in the form of hydroxides and cause losses. Therefore, in order to ensure the recovery rate of scandium and a lower loss rate of cobalt, nickel, and manganese, the endpoint pH should be controlled at 3.0-4.0, and the temperature should be controlled at 25-45°C.

[0077] During the first scandium precipitation treatment to separate and recover scandium, the endpoint pH and reaction temperature are controlled so that scandium and cobalt, nickel and manganese are well separated, the loss rate of cobalt, nickel and manganese into slag is less than 1%, the yield of scandium is high, and no additional by-products are generated. The solution after separation and recovery of scandium (crude nickel sulfate solution) can continue to produce cobalt, nickel and manganese related products.

[0078] In some embodiments of the present invention, in step S2, the temperature of the first acid dissolution is 75-95°C; typically but not limitatively, for example, the temperature of the first acid dissolution can be 75°C, 80°C, 85°C, 90°C, 95°C or a range of any two thereof.

[0079] In some embodiments of the present invention, in step S2, the first acid dissolution time is 0.5 to 1 h; typically but not limiting, for example, the first acid dissolution time can be 0.5 h, 0.75 h, 1 h or a range of any two thereof.

[0080] In some embodiments of the present invention, in step S2, the endpoint acidity of the first acid dissolution is 3-5N; typically but not limiting, for example, the endpoint acidity of the first acid dissolution can be 3N, 4N, 5N or a range consisting of any two of them.

[0081] In some embodiments of the present invention, in step S2, the concentration of the sulfuric acid solution is 150-300 g / L.

[0082] In some embodiments of the present invention, in step S2, the content of scandium in the scandium sulfate solution is 5-40 g / L.

[0083] Under the above conditions, the first scandium concentrate is first acid-dissolved with sulfuric acid to obtain a scandium sulfate solution that meets the double salt precipitation conditions, thereby ensuring a higher scandium precipitation rate.

[0084] In some embodiments of the present invention, in step S3, the second precipitating agent includes ammonium sulfate.

[0085] In some embodiments of the present invention, in step S3, the molar ratio of the second precipitant to the scandium element in the scandium sulfate solution is 1:(2-2.5); typically but not limitatively, for example, the molar ratio of the second precipitant to the scandium element in the scandium sulfate solution can be 1:2, 1:2.1, 1:2.2, 1:2.3, 1:2.4, 1:2.5 or a range of any two thereof.

[0086] In some embodiments of the present invention, in step S3, the scandium sulfate solution and the ammonium source are mixed to obtain a mixed solution; the mixed solution and a second precipitant are subjected to a double salt precipitation treatment to obtain a second scandium-enriched product.

[0087] In some embodiments of the present invention, in step S3, the concentration of ammonium ions in the mixed solution is 0.5 mol / L; the concentration of ammonium ions in the scandium sulfate solution system treated with the second precipitant for precipitation of double salt should be ensured to be 0.5 mol / L.

[0088] In some embodiments of the present invention, in step S3, the ammonium source includes one or more of ammonium chloride, ammonium sulfate and ammonium acetate.

[0089] In some embodiments of the present invention, in step S3, the temperature for precipitation of double salt treatment is 25-90°C; typically but not limiting, for example, the temperature for precipitation of double salt treatment can be 25°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C or a range of any two thereof.

[0090] In some embodiments of the present invention, in step S3, the time for precipitating double salt treatment is 0.5 to 1.5 h; typically but not limiting, for example, in step S3, the time for precipitating double salt treatment can be 0.5 h, 1 h, 1.5 h or a range of any two thereof.

[0091] In the precipitation double salt treatment, the double salt generated by the reaction of ammonium sulfate and scandium is ammonium sulfate scandium (NH4Sc(SO4)2). When the ammonium ion concentration in the system is maintained at 0.5 mol / L, the separation coefficient between scandium and impurities such as cobalt, nickel, iron, and aluminum is large, and scandium and other impurities can be well separated. A high-grade scandium enriched product and post-scandium precipitation liquid can be obtained, and the post-scandium precipitation liquid can be reused for precipitation double salt treatment.

[0092] In some embodiments of the present invention, the second enriched material is calcined at a temperature of 400-700°C; typically but not limiting, for example, the second enriched material is calcined at a temperature of 400°C, 500°C, 600°C, 700°C or a range of any two thereof.

[0093] In some embodiments of the present invention, the second enriched material is calcined for 1 to 4 hours. Typically but not limiting, for example, the second enriched material is calcined for 1 hour, 2 hours, 3 hours, 4 hours or a range of any two thereof.

[0094] In some embodiments of the present invention, the second enriched product calcination is performed under an air atmosphere.

[0095] In some embodiments of the present invention, the main component of the third scandium-enriched product is scandium sulfate.

[0096] When the second scandium enriched product is calcined, at different calcination temperatures, scandium ammonium sulfate will be transformed into different decomposition products, and the specific reaction equations are: calcination temperature is 400-520°C, 2NH4Sc(SO4)2+2O2=Sc2(SO4)3+2NO+SO2+4H2O; calcination temperature>800°C, 2Sc2(SO4)3=2Sc2O3+6SO2+3O2, so to obtain scandium sulfate, the calcination temperature should be controlled at 400-700°C.

[0097] In some embodiments of the present invention, in step S4, the endpoint pH of the second acid dissolution is 1.0-1.3; typically but not limiting, for example, the endpoint pH of the second acid dissolution can be 1.0, 1.1, 1.2, 1.3 or a range of any two thereof.

[0098] In some embodiments of the present invention, in step S4, the temperature of the second acid dissolution is 70-90°C; typically but not limiting, for example, the temperature of the second acid dissolution can be 70°C, 80°C, 90°C or a range of any two thereof.

[0099] In some embodiments of the present invention, in step S4, the second acid dissolution time is 1 to 3 hours; typically but not limiting, for example, the second acid dissolution time can be 1 hour, 2 hours, 3 hours or a range of any two thereof.

[0100] Under the above conditions, the third scandium concentrate is acid-dissolved with a hydrochloric acid solution, so that the scandium can be selectively dissolved out, and the scandium can be further separated from impurities such as iron and aluminum.

[0101] In some embodiments of the present invention, in step S4, the mass percentage of the oxalic acid solution is 10 wt % to 30 wt %.

[0102] In some embodiments of the present invention, in step S4, the endpoint pH of the second scandium precipitation treatment is 1.0-1.3; typically but not limiting, for example, the endpoint pH of the second scandium precipitation treatment can be 1.0, 1.1, 1.2, 1.3 or a range of any two thereof.

[0103] In some embodiments of the present invention, in step S4, the temperature of the second scandium deposition treatment is 70-90°C; typically but not limiting, for example, the temperature of the second scandium deposition treatment can be 70°C, 80°C, 90°C or a range of any two thereof.

[0104] In some embodiments of the present invention, in step S4, the second scandium deposition treatment time is 1 to 3 hours. Typically but not limiting, for example, the second scandium deposition treatment time can be 1 hour, 2 hours, 3 hours, or a range of any two thereof.

[0105] The second scandium precipitation treatment is carried out using oxalic acid under the above conditions, so that most of the impurities that do not precipitate with oxalic acid under the conditions of the present invention can be separated, and a scandium-containing precipitate with higher purity can be obtained.

[0106] In some embodiments of the present invention, in step S4, the temperature of calcining the scandium-containing precipitate is 600-800°C; typically but not limiting, for example, the temperature of calcining the scandium-containing precipitate can be 600°C, 650°C, 700°C, 750°C, 800°C or a range of any two thereof.

[0107] In some embodiments of the present invention, in step S4, the scandium-containing precipitate is calcined for 2 to 3 hours; typically but not limiting, for example, the scandium-containing precipitate is calcined for 2 hours, 2.5 hours, 3 hours or a range of any two thereof.

[0108] In some embodiments of the present invention, the calcination of the scandium-containing precipitate is performed under an air atmosphere.

[0109] Example 1

[0110] The method for recovering scandium from a cobalt-nickel hydroxide intermediate provided in this embodiment comprises the following steps:

[0111] S1. Mixing a cobalt nickel hydroxide (MHP) intermediate, sodium pyrosulfite solid powder and a sulfuric acid solution, wherein the amount of sodium pyrosulfite added is the sum of 0.5 times the molar amount of cobalt and 1 times the molar amount of manganese contained in the cobalt nickel hydroxide intermediate, performing normal pressure reduction leaching at pH 2.5 and 70° C. for 1.5 h, and filtering to obtain a leachate;

[0112] S2, adding sodium pyrosulfite to the above leachate, the molar ratio of sodium pyrosulfite to scandium element in the leachate is 1:1.3, performing a first scandium precipitation treatment at pH 4.0 and 35-40°C for 1.5h, filtering to obtain a first scandium enriched product and a crude nickel sulfate solution; mixing the first scandium enriched product with a sulfuric acid solution having a concentration of 250g / L, performing a first acid dissolution at 80°C, the reaction time is 1h, the end point acidity is 5N, filtering to obtain a scandium sulfate solution, the scandium content in the scandium sulfate solution is 30g / L;

[0113] S3, adding ammonium chloride solid powder to the above scandium sulfate solution, maintaining the ammonium concentration in the solution system at 0.5 mol / L, then heating to 80°C, slowly adding ammonium sulfate solid (the molar ratio of ammonium sulfate solid to scandium element in the scandium sulfate solution is 1:2) to precipitate double salt for 1 hour, filtering to obtain a scandium precipitation solution and a second enriched product; calcining the second scandium enriched product at 700°C in an air atmosphere for 3 hours to obtain a third enriched product;

[0114] S4. The third enriched product and the hydrochloric acid solution are mixed for the second acid dissolution, and the reaction is carried out at 80°C for 2 hours, and the end point pH is 1.3 to obtain a scandium chloride solution; an oxalic acid solution with a concentration of 30wt% is added for the second scandium precipitation treatment. At 80°C, the end point pH is controlled to be 1.3 using a 250g / L sodium carbonate solution. After the scandium precipitation treatment for 2 hours, it is filtered to obtain a scandium-containing precipitate; the scandium-containing precipitate is calcined at 700°C for 3 hours in an air atmosphere to obtain scandium oxide.

[0115] Example 2

[0116] The method for recovering scandium from a cobalt-nickel hydroxide intermediate provided in this embodiment comprises the following steps:

[0117] S1. Mixing a cobalt nickel hydroxide (MHP) intermediate, a sodium pyrosulfite solid powder and a sulfuric acid solution, wherein the amount of sodium pyrosulfite added is the sum of 0.5 times the molar amount of cobalt and 1 times the molar amount of manganese contained in the cobalt nickel hydroxide intermediate, performing normal pressure reduction leaching at pH 3.0 and 70° C. for 1.5 hours, and filtering to obtain a leachate;

[0118] S2, adding sodium pyrosulfite to the above leachate, the molar ratio of sodium pyrosulfite to scandium element in the leachate is 1:1.5, and performing a first scandium precipitation treatment at pH 3.5 and 35-40°C for 1.5h, and filtering to obtain a first scandium enriched product and a crude nickel sulfate solution; mixing the first scandium enriched product with a sulfuric acid solution having a concentration of 250g / L, and performing a first acid dissolution at 80°C, the reaction time is 1h, the end point acidity is 5N, and filtering to obtain a scandium sulfate solution, the scandium content in the scandium sulfate solution is 20g / L;

[0119] S3, adding ammonium chloride solid powder to the above scandium sulfate solution, maintaining the ammonium concentration in the solution system at 0.5 mol / L, then heating to 80°C, slowly adding ammonium sulfate solid (the molar ratio of ammonium sulfate solid to scandium element in the scandium sulfate solution is 1:2) to precipitate double salt for 1 hour, filtering to obtain a scandium precipitation solution and a second enriched product; calcining the second scandium enriched product at 700°C in an air atmosphere for 3 hours to obtain a third enriched product;

[0120] S4. The third enriched product and the hydrochloric acid solution are mixed for the second acid dissolution, and the reaction is carried out at 80°C for 2 hours, and the end point pH is 1.3 to obtain a scandium chloride solution; an oxalic acid solution with a concentration of 25wt% is added for the second scandium precipitation treatment. At 80°C, the end point pH is controlled to be 1.3 using a 250g / L sodium carbonate solution. After the scandium precipitation treatment for 2 hours, it is filtered to obtain a scandium-containing precipitate; the scandium-containing precipitate is calcined at 700°C for 3 hours in an air atmosphere to obtain scandium oxide.

[0121] Example 3

[0122] The method for recovering scandium from the cobalt nickel hydroxide intermediate provided in this embodiment refers to Example 1, except that in step S2, the molar ratio of sodium pyrosulfite to the scandium element in the leaching solution is 1:3.

[0123] Example 4

[0124] The method for recovering scandium from the cobalt nickel hydroxide intermediate provided in this embodiment refers to Example 1, except that in step S2, the molar ratio of sodium pyrosulfite to the scandium element in the leaching solution is 1:1.

[0125] Example 5

[0126] The method for recovering scandium from the cobalt nickel hydroxide intermediate provided in this embodiment refers to Example 1, with the only difference being that in step S2, the concentration of the sulfuric acid solution is 100 g / L.

[0127] Example 6

[0128] The method for recovering scandium from the cobalt nickel hydroxide intermediate provided in this embodiment refers to Example 1, with the only difference being that in step S2, during the first acid dissolution, the liquid-to-solid ratio of the first scandium enriched product and the sulfuric acid solution is controlled so that the scandium content in the obtained scandium sulfate solution is 3 g / L.

[0129] Example 7

[0130] The method for recovering scandium from the cobalt nickel hydroxide intermediate provided in this embodiment refers to Example 1, except that in step S2, the first scandium precipitation treatment is carried out at a pH of 5.0 and 35-40° C. for 1.5 h.

[0131] Example 8

[0132] The method for recovering scandium from the cobalt nickel hydroxide intermediate provided in this embodiment refers to Example 1, except that in step S3, no solid ammonium chloride powder is added.

[0133] Example 9

[0134] The method for recovering scandium from the cobalt hydroxide nickel intermediate provided in this embodiment refers to Example 1, with the only difference being that in step S3, the temperature is heated to 25°C, and ammonium sulfate solid (the molar ratio of ammonium sulfate solid to scandium element in scandium sulfate solution is 1:2) is slowly added to precipitate double salt for 1 hour.

[0135] Test example

[0136] The contents of the main components of the leachate obtained by atmospheric pressure reduction leaching in Example 1 and Example 2 are shown in Table 1, unit: g / L.

[0137] Table 1

[0138] Co Ni Mn Sc Example 1 6.57 85.42 12.24 1.87 Example 2 6.91 95.43 10.43 1.70

[0139] The main components of the crude nickel sulfate solutions of Examples 1 to 4 and Example 7 and the precipitation rates of the first scandium precipitation treatment are shown in Table 2.

[0140] Table 2

[0141]

[0142]

[0143] The precipitation rates of various metals and the purity of scandium oxide in the precipitation double salt treatment of Examples 1 to 9 are shown in Table 3.

[0144] Table 3

[0145]

[0146] It can be seen from Tables 1 to 3 that in Example 1 and Example 2, the precipitation rate of cobalt, nickel and manganese in the first precipitation scandium treatment is less than 1%, the precipitation rate of scandium is greater than 99%, and the precipitation rate of scandium treated with precipitation double salt is greater than 99.9%. Therefore, the separation effect of scandium from nickel, cobalt and manganese is good, and almost no loss of cobalt, nickel and manganese is caused in the process. The purity of the final scandium oxide is greater than 99.4%.

[0147] In summary, the method for recovering scandium from the cobalt-nickel hydroxide intermediate of the present invention can achieve the separation of cobalt-nickel-manganese and scandium, while maintaining a high scandium recovery rate to obtain scandium oxide with higher purity.

[0148] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for recovering scandium from a cobalt-nickel hydroxide intermediate, characterized in that: The steps include: S1, subjecting the cobalt-nickel hydroxide intermediate, a reducing agent and a sulfuric acid solution to atmospheric pressure reduction leaching to obtain a leachate; S2, subjecting the leachate and the first precipitant to a first scandium precipitation treatment to obtain a first scandium-enriched product and a crude nickel sulfate solution; subjecting the first scandium-enriched product and the sulfuric acid solution to a first acid dissolution to obtain a scandium sulfate solution; S3, treating the scandium sulfate solution and the second precipitant with a precipitated double salt to obtain a second scandium-enriched product; and calcining the second scandium-enriched product to obtain a third scandium-enriched product; S4, subjecting the third scandium-enriched product and the hydrochloric acid solution to a second acid dissolution to obtain a scandium chloride solution; The scandium chloride solution and the oxalic acid solution are subjected to a second scandium precipitation treatment to obtain a scandium-containing precipitate; and the scandium-containing precipitate is calcined to obtain scandium oxide.

2. The method for recovering scandium from a cobalt-nickel hydroxide intermediate according to claim 1, characterized in that: In step S1, the ratio of the molar number of the reducing agent to the total molar number of the cobalt element and the manganese element in the cobalt nickel hydroxide intermediate is 1:(1.4-1.6); And / or, the reducing agent includes at least one of sodium pyrosulfite, sulfur oxide, hydrogen peroxide and sodium thiosulfate.

3. The method for recovering scandium from a cobalt-nickel hydroxide intermediate according to claim 2, characterized in that: In step S1, at least one of the following features (1) to (3) is included; (1) The endpoint pH of the atmospheric pressure reduction leaching is 2.0 to 3.0; (2) The temperature of the atmospheric pressure reduction leaching is 45 to 75° C.; (3) The normal pressure reduction leaching time is 0.5 to 2 hours.

4. The method for recovering scandium from a cobalt-nickel hydroxide intermediate according to claim 3, characterized in that: In step S2, the first precipitant includes sodium sulfite and / or sodium pyrosulfite; And / or, the molar ratio of the first precipitant to the scandium element in the leaching solution is 1:(1-1.5).

5. The method for recovering scandium from a cobalt-nickel hydroxide intermediate according to claim 4, characterized in that: In step S2, at least one of the following features (1) to (7) is included; (1) The endpoint pH of the first scandium precipitation treatment is 3.0 to 4.0; (2) The temperature of the first scandium precipitation treatment is 25 to 45° C.; (3) The first scandium precipitation treatment time is 0.5 to 3 hours; (4) The temperature of the first acid solution is 75 to 95° C.; (5) The first acid dissolution time is 0.5 to 1 h; (6) The endpoint acidity of the first acid solution is 3 to 5N; (7) The concentration of the sulfuric acid solution is 150 to 300 g / L.

6. The method for recovering scandium from a cobalt-nickel hydroxide intermediate according to claim 5, characterized in that: In step S3, the second precipitant includes ammonium sulfate; And / or, the molar ratio of the second precipitant to the scandium element in the scandium sulfate solution is 1:(2-2.5).

7. The method for recovering scandium from a cobalt-nickel hydroxide intermediate according to claim 6, characterized in that: In step S3, the scandium sulfate solution and the ammonium source are mixed to obtain a mixed solution; the mixed solution and the second precipitant are subjected to a double salt precipitation treatment to obtain the second scandium enriched product; Preferably, the concentration of ammonium in the mixed solution is 0.5 mol / L; Preferably, the ammonium source includes one or more of ammonium chloride, ammonium sulfate and ammonium acetate.

8. The method for recovering scandium from a cobalt-nickel hydroxide intermediate according to claim 7, characterized in that: In step S3, at least one of the following features (1) to (4) is included; (1) The temperature of the precipitation double salt treatment is 25 to 90° C.; (2) The precipitation double salt treatment time is 0.5 to 1.5 hours; (3) The second enriched product is calcined at a temperature of 400 to 700° C.; (4) The calcination time of the second enriched product is 1 to 4 hours.

9. The method for recovering scandium from a cobalt-nickel hydroxide intermediate according to claim 8, characterized in that: In step S4, at least one of the following features (1) to (3) is included; (1) The endpoint pH of the second acid solution is 1.0 to 1.3; (2) the temperature of the second acid solution is 70 to 90° C.; (3) The second acid dissolution time is 1 to 3 hours.

10. The method for recovering scandium from a cobalt-nickel hydroxide intermediate according to claim 8, characterized in that: In step S4, at least one of the following features (1) to (6) is included; (1) The mass percentage of the oxalic acid solution is 10wt% to 30wt%; (2) The endpoint pH of the second scandium precipitation treatment is 1.0 to 1.3; (3) The temperature of the second scandium precipitation treatment is 70-90° C.; (4) The second precipitation scandium treatment time is 1 to 3 hours; (5) The calcination temperature of the scandium-containing precipitate is 600-800° C.; (6) The calcination time of the scandium-containing precipitate is 2 to 3 hours.

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