A method for separating scandium and yttrium from crude nickel cobalt hydroxide

Abstract

The present invention belongs to the technical field of hydrometallurgy, and specifically relates to a method for separating scandium and yttrium from crude nickel cobalt hydroxide, which comprises the following steps: adding water and acid to the crude nickel cobalt hydroxide for dissolution reaction, adding the crude nickel cobalt hydroxide to adjust the pH value, performing solid-liquid separation to obtain an acid solution and an acid leaching residue; removing silicon, performing precision filtration, and performing solvent extraction to obtain a loaded organic phase and a raffinate; washing the loaded organic phase to obtain organic phase I; using a mixed solution of hydrochloric acid and oxalic acid with different gradient concentrations from low to high to sequentially perform preliminary stripping of yttrium, deep stripping of yttrium, and stripping of scandium on the loaded organic phase to obtain a scandium oxalate precipitate, and then performing precipitate washing, drying, and calcination to obtain scandium oxide; performing yttrium precipitation, precipitate washing, and calcination on the third washing solution obtained by stripping yttrium to obtain yttrium oxide. The method of the present invention solves the technical problem that it is difficult to completely separate scandium and yttrium during the solvent extraction of nickel and cobalt, and long-term accumulation is likely to hinder the normal operation of the extraction system.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydrometallurgy, and particularly relates to a method for separating scandium and yttrium from crude nickel-cobalt hydroxide. Background Art

[0002] Due to their special physical and chemical properties, scandium and yttrium have broad application prospects in the fields of preparing special steels, non-ferrous alloys, fuel cells, high-performance ceramics, etc. There are more than 800 kinds of scandium-containing minerals in nature, but those with Sc2O3>500 g / t are very few, and independent minerals of scandium are even extremely rare. Therefore, the most widely used method in industry is to recover scandium from intermediate products / smelting waste residues. Generally, it is considered that when the scandium content reaches 20 g / t, it has the value of recovery. However, scandium is often associated with other rare metals and is difficult to be completely separated due to similar properties. Among them, crude nickel-cobalt hydroxide is mostly obtained by extracting most of the scandium from laterite nickel ore and removing most of the impurities such as iron and aluminum. In the prior art, the treatment method of nickel-cobalt hydroxide is mainly to dissolve the valuable metals in it with inorganic acid under atmospheric pressure or pressure, and then remove the impurity ions other than nickel and cobalt from the acid solution by one or more stages of chemical precipitation method or combined extraction and purification method. Finally, nickel and cobalt are separated and nickel and cobalt are recovered respectively. In the above process, scandium and yttrium in the raw materials will enter the purification slag or extractant during the purification process. Since the yttrium content is usually much lower than the scandium content, the accumulation rate of yttrium during the production process is much lower than that of scandium, and it is not easy to hinder the normal operation of the production system. Therefore, the existence of yttrium element is not easy to be found, so usually only scandium is concerned and the recovery of yttrium is ignored. When solvent extraction method is used to recover scandium, common extractants such as P204, P507, C272, P350, neutral phosphorus extractant TBP, amine extractant, composite extractant, etc. can all achieve the effect of loading scandium in the feed liquid onto the organic phase. The commonly used detergent is inorganic acid solution, and the stripping agent is inorganic acid or oxalic acid or alkaline solution. To further recover the scandium in it, the stripped solution can be further processed by inorganic acid back-dissolution, precipitation, extraction, washing, stripping, calcination and other methods to produce high-purity scandium oxide, while there are few reports on the simultaneous recovery or separation of valuable metal yttrium in it.

[0003] For the separation of scandium and yttrium, the following method is usually referred to: first, scandium and other rare earth metal ions are extracted into the organic phase together, and then the rare earth-loaded organic phase is stripped separately. In the prior art, the most disclosed is the process of hydrochloric acid stripping and oxalic acid precipitation. However, in the process of extracting and separating rare earth elements with acidic phosphorus extractant, scandium and yttrium are complexed with the extractant stably and are difficult to be completely stripped. Also, due to their similar properties, it is difficult to be completely separated. To improve the stripping rate of scandium and yttrium, it is usually necessary to use a stripping solution with a higher acidity. Moreover, the separation of scandium and yttrium is not complete. If the acidity of the stripping solution is insufficient, it is easy to cause incomplete stripping of heavy rare earth elements in the organic phase and gradual accumulation, making the stripping more and more difficult, and finally making the process unable to proceed.

[0004] Therefore, it becomes very necessary to research and develop a method to separate scandium and yttrium from crude nickel-cobalt hydroxide, recover them separately, and at the same time solve the problems that scandium and yttrium are difficult to separate during the solvent extraction process of nickel and cobalt extraction, and the long-term accumulation of yttrium is likely to hinder normal production. Summary of the Invention

[0005] The present invention aims to solve the above technical problems and provides a method for separating scandium and yttrium from crude nickel-cobalt hydroxide, which solves the technical problems in the prior art that it is difficult to simultaneously separate high-purity scandium and yttrium from crude nickel-cobalt hydroxide, that is, scandium and yttrium are difficult to be completely separated during the solvent extraction process of nickel and cobalt, and the long-term accumulation is likely to hinder the normal operation of the extraction system.

[0006] The technical solution of the present invention is as follows:

[0007] A method for separating scandium and yttrium from crude nickel-cobalt hydroxide, comprising the following steps:

[0008] (1) Dissolution: Pulverize crude nickel-cobalt hydroxide with water, add inorganic acid, control the end point pH value to be 0.5 - 1.5, react, continue to add crude nickel-cobalt hydroxide to adjust the pH value back to 2.5 - 3.5, separate the solid and liquid after reaction to obtain an acid solution and an acid-insoluble residue, subject the acid solution to flocculation for silicon removal, static settlement and then solid-liquid separation to obtain a silicon-removed solution, and obtain an extraction stock solution after precision filtration of the silicon-removed solution;

[0009] (2) Solvent extraction: Mix a composite extractant with the extraction stock solution for extraction to obtain a loaded organic phase and a raffinate;

[0010] (3) Washing: Use a hydrochloric acid solution with a concentration of 8 - 10 mol / L as a washing solution to wash the loaded organic phase to obtain a first washing solution and an organic phase I;

[0011] (4) Separation of scandium and yttrium: Use a hydrochloric acid solution with a concentration of 2 - 4 mol / L and an oxalic acid solution with a mass concentration of 5 - 10% as a washing solution, mix with the organic phase I to preliminarily back-extract yttrium to obtain a second washing solution and an organic phase II; continue to use a hydrochloric acid solution with a concentration of 4 - 6 mol / L and an oxalic acid solution with a mass concentration of 11 - 13% as a yttrium back-extractant, mix with the organic phase II to deeply back-extract yttrium to obtain a third washing solution and an organic phase III; continue to use a hydrochloric acid solution with a concentration of 6 - 8 mol / L and an oxalic acid solution with a mass concentration of 15 - 18% as a scandium back-extractant, mix with the organic phase III, control the back-extraction temperature to be 40 - 80 °C, separate the organic phase to obtain a scandium oxalate precipitate;

[0012] (5) Wash, dry and calcine the scandium oxalate precipitate to obtain high-purity scandium oxide;

[0013] (6) Heat the third washing solution, adjust the pH value to 1.5 - 2.5, carry out yttrium precipitation, keep warm for aging, separate solid from liquid, wash yttrium oxalate with water, and calcine to obtain yttrium oxide.

[0014] Preferably, in step (1) of the present invention, the crude nickel - cobalt hydroxide is slurried with water, an inorganic acid is added, the end - point pH value is controlled to be 0.5 - 1.5, the reaction is carried out for 0.5 - 1 h, then the crude nickel - cobalt hydroxide is continuously added to adjust the pH value back to 2.5 - 3.5, and after reacting for 1 - 4 h, solid - liquid separation is carried out to obtain an acid solution and an acid - soluble residue; preferably, the inorganic acid is one of hydrochloric acid solution, sulfuric acid solution, and nitric acid solution. In step (1) of the present invention, when the crude nickel - cobalt hydroxide is leached, first controlling the high acidity of the system and then adjusting the pH with the crude nickel - cobalt hydroxide can improve the leaching rates of scandium and yttrium in the nickel - cobalt hydroxide, and at the same time can neutralize and remove most of the iron, reducing the iron content in the acid solution.

[0015] Preferably, in step (1) of the present invention, the flocculant used for silicon removal by flocculation is polyacrylamide with a mass concentration of 0.1% - 0.5%, and the addition amount of the flocculant is 1 - 5 L / m 3 acid solution, and the static sedimentation time is 0.5 - 10 h.

[0016] Preferably, in step (2) of the present invention, the ratio of the composite extractant to the original extraction solution is 1 - 3:1, the single - stage extraction time is 5 - 15 min, the extraction method is counter - current extraction for 3 - 5 stages, and the pH of the raffinate is controlled at 2.5 - 3.5. Preferably, in the composite extractant of the present invention, the components and their volume ratios are: P507 10 - 20%, modifier 0 - 10%, diluent 75 - 85%. By flocculating and removing silicon from the acid solution and then carrying out precision filtration in the front, and introducing a modifier during solvent extraction, the present invention can prevent emulsification and interfacial dirt during extraction, so as to quickly separate phases and improve production efficiency.

[0017] Preferably, the saponification rate of P507 in the present invention is 0 - 100%, the modifier is tributyl phosphate, and the diluent is sulfonated kerosene. Among them, the P507 extractant can be saponified with liquid alkali or ammonia water.

[0018] Preferably, in step (3) of the present invention, the washing ratio is 0.5 - 2:1, and the hydrochloric acid concentration in the first washing solution is controlled at 6 - 9.5 mol / L. In this step, by first washing the loaded organic phase with a high - concentration hydrochloric acid solution, the iron, zinc, calcium, copper, and manganese loaded in the organic phase can be removed, so as not to affect the purity of the subsequent recovered products of scandium and yttrium, and at the same time, the phenomenon of calcium sulfate crystallization blocking the pipe can be avoided, reducing production efficiency.

[0019] Preferably, in step (4) of the present invention, the volume ratios of the hydrochloric acid solution and the oxalic acid solution are both 1 - 3:1.

[0020] Preferably, in the step (4), the acidity of the second washing solution is controlled to be 2-4 mol / L, the acidity of the third washing solution is 4-6 mol / L, and the washing ratio is 0.5-2:1 in both cases. In this step, the present invention first washes the yttrium loaded in the organic phase after washing iron, zinc, and calcium with a mixed solution of hydrochloric acid solution and oxalic acid solution at a lower concentration, which can initially remove the loaded yttrium therein, and at the same time does not wash scandium together. Moreover, no precipitate is formed in the washed system, avoiding the problems of direct washing or back-extraction with oxalic acid solution, oxalate, or alkali solution, such as the generation of precipitates, three-phase, and difficulties in separating the organic phase and the aqueous phase. It also avoids the problem of poor washing effect on yttrium when simply washing or back-extracting with hydrochloric acid solution. Then, by using a mixed solution of hydrochloric acid solution and oxalic acid solution at a higher concentration to deeply back-extract the yttrium loaded in the organic phase, it can avoid the influence of residual yttrium on the purity of scandium oxide. In addition, since scandium has a stronger affinity with the composite extractant (the main extractant P507) and is preferentially extracted, and yttrium has a relatively strong affinity with the composite extractant and is relatively difficult to be extracted under the same conditions, but by controlling the extraction conditions, the above two ions can be co-extracted. When back-extracting, if scandium, which has a stronger affinity with the extractant, wants to be back-extracted, more stringent conditions are required, that is, a high-concentration mixed acid is needed to completely back-extract scandium. If the yttrium loaded in it is first washed with a mixed solution of hydrochloric acid solution and oxalic acid solution at a higher concentration, while yttrium is washed down, scandium will also be partially back-extracted into the washing solution, and scandium and yttrium will enter the washing solution simultaneously, resulting in the inability to separate scandium and yttrium during the washing process.

[0021] Preferably, in the step (5) of the present invention, the drying temperature is 80-120 °C, the calcination temperature is 800-1000 °C, and the calcination time is 1-3 h.

[0022] Preferably, the step (6) of the present invention is specifically as follows: heating the third washing solution to 40-60 °C, adjusting the pH value to 1.5-2.5, performing yttrium precipitation for 1-2 h, maintaining the temperature for aging for 3-6 h, separating the solid and liquid to obtain yttrium oxalate, washing yttrium oxalate with water, and calcining at 800-1200 °C for 1-3 h to obtain yttrium oxide. Preferably, ammonia water with a mass concentration of 5-15% is used to adjust the pH value.

[0023] In order to enhance the effect of circulating washing, after concentrating the first washing solution, the second washing solution, and the third washing solution, they can be continuously used for the washing process in steps (3)-(4) for continuous washing. The washing temperature is controlled at 30-50 °C, the single-stage washing time is 5-15 min, and the number of washing stages is 1-3.

[0024] Due to the adoption of the above technical solutions, the beneficial effects of the present invention are as follows:

[0025] 1. The method of the present invention can solve the technical problem that it is difficult to simultaneously separate high-purity scandium and yttrium from crude nickel-cobalt hydroxide in the prior art, that is, it is difficult to completely separate scandium and yttrium during the solvent extraction process of nickel and cobalt, and the long-term accumulation is likely to hinder the normal operation of the extraction system.

[0026] 2. By using the method of the present invention, high-purity scandium oxide and yttrium oxide can be obtained simultaneously. The purity of scandium oxide can reach more than 99.99%, and the product meets the Sc2O3-4N standard; the purity of yttrium oxide reaches more than 99%, and the product meets the Y2O3-3NC standard.

[0027] 3. By using the method of the present invention, not only can scandium and yttrium be simultaneously recovered from crude nickel-cobalt hydroxide, but also the long-term accumulation of the two on the extraction system can be avoided, and the performance of the extractant can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a process flow chart of the method for separating scandium and yttrium from crude nickel-cobalt hydroxide of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0030] Example 1

[0031] (1) Dissolution: 1 kg of crude nickel-cobalt hydroxide (main components are as follows: Sc 0.0041 wt%, Y 0.0015 wt%, Ni 28.95 wt%, Co 1.20 wt%, Fe 0.025 wt%, SiO2 0.35 wt%) is made into a slurry by adding water according to a liquid-solid mass ratio of 0.5:1, and a sulfuric acid solution with a mass concentration of 50% is added. First, the end point pH value is controlled to be 1.5, and the reaction is carried out for 1 h. Then, crude nickel-cobalt hydroxide is added to adjust the pH value back to 2.5. After reacting for 1 h, solid-liquid separation is carried out to obtain an acid solution and an acid-soluble residue. The mass dissolution rates of each component are as follows: Sc 90.14%, Y 90.22%, Ni 95.95%, Co 92.20%, Fe 0.27%, SiO2 34.86%. A PAM flocculant with a mass concentration of 0.1% is added to the acid solution, and the dosage of the flocculant is 5 L / m 3 acid solution. After starting stirring and mixing for 0.5 h, then standing and settling for 0.5 h, solid-liquid separation is carried out to obtain a silicon-removed solution. The silicon removal rate is 65.33%. After the silicon-removed solution is precisely filtered, the extraction stock solution is obtained;

[0032] (2) Solvent extraction: Prepare a composite extractant. The components and their volume percentages in the composite extractant are: P507 10%, TBP 10%, sulfonated kerosene 80%, without saponification; Mix the composite extractant with the original extraction solution in a phase ratio of 1:1 and perform countercurrent extraction for 5 stages. The single-stage extraction time is 5 min, the temperature is 30 °C. After extraction, phase separation is carried out to obtain the loaded organic phase and the raffinate. The pH value of the raffinate is 2.5. The extraction rates of each component are as follows: Sc 90.00%, Y 90.28%, Ni <0.1%, Co <0.1%, Mn <0.1%, Fe 100%, Cu <0.1%, Zn 95.03%, Ca 0.42%;

[0033] (3) Washing: Use a 10 mol / L hydrochloric acid solution as the washing solution to wash the loaded organic phase to remove iron, zinc, calcium, copper, and manganese, obtaining the first washing solution and organic phase I; The washing phase ratio is 0.5:1, the washing temperature is 30 °C, the single-stage washing time is 5 min, and the washing method is countercurrent washing for 3 stages. The hydrochloric acid concentration in the first washing solution is 9.5 mol / L;

[0034] (4) Separation of scandium and yttrium: Use a washing solution of a 2 mol / L hydrochloric acid solution and a 5% mass concentration oxalic acid solution with a volume ratio of 1:1, mix it with organic phase I, and after washing, phase separation is carried out to preliminarily back-extract yttrium, obtaining the second washing solution and organic phase II; Continue to use a 4 mol / L hydrochloric acid solution and an 11% mass concentration oxalic acid solution with a volume ratio of 1:1 as the yttrium back-extractant, mix it with organic phase II, and after washing, phase separation is carried out to deeply back-extract yttrium, obtaining the third washing solution and organic phase III; Continue to use a 6 mol / L hydrochloric acid solution and a 15% mass concentration oxalic acid solution with a volume ratio of 1:1 as the scandium back-extractant, mix it with organic phase III, control the back-extraction temperature at 40 °C, the back-extraction time at 1 h. After back-extraction, the organic phase is separated (phase separation) to obtain scandium oxalate precipitate; In the above process, the washing / back-extraction phase ratio is controlled at 0.5:1, the temperature is 30 °C, the single-stage washing / back-extraction time is 5 min, and the washing / back-extraction method is countercurrent washing for 3 stages. The acidity of the second washing solution is 4 mol / L, and the acidity of the third washing solution is 6 mol / L;

[0035] (5) Wash the scandium oxalate precipitate with water, dry it, and calcine it to obtain high-purity scandium oxide. The purity of scandium oxide reaches 99.99%, and the impurity content meets the requirements of Sc2O3-4N in scandium oxide in GB / T 13219-2018 (see Table 1), where the yttrium content is 0.0007%; Among them, the washing conditions are normal temperature washing, the water addition amount is according to the liquid-solid mass ratio of 1:1, the washing time is 0.5 h, the washing stage number is 2 stages. After washing, solid-liquid separation is carried out to obtain the washed scandium oxalate and the washing solution. The drying temperature of the washed scandium oxalate is 80 °C, the calcination temperature is 800 °C, and the calcination time is 3 h.

[0036] (6) Heat the third washing solution to 40 °C, add ammonia water with a mass concentration of 15% to adjust the pH value to 1.5, carry out yttrium precipitation, the yttrium precipitation time is 1 h, keep warm and age for 3 h. After the aging is completed, solid-liquid separation is carried out to obtain yttrium oxalate, wash yttrium oxalate with water and calcine it at a high temperature. The calcination temperature is 800 °C and the calcination time is 3 h to obtain yttrium oxide. The purity of yttrium oxide reaches 99.90%, and the impurity content meets the requirements of Y2O3-3NC in yttrium oxide of GBT 3503-2015 (see Table 2), and the scandium content is 0.0015%.

[0037] Example 2

[0038] (1) Dissolution: Take 10 kg of crude nickel-cobalt hydroxide (the main components are as follows: Sc 0.0099 wt%, Y 0.010 wt%, Ni 32.26 wt%, Co 2.53 wt%, Fe 0.63 wt%, SiO2 0.66 wt%), make a pulp by adding water according to the liquid-solid mass ratio of 1:1, add concentrated sulfuric acid solution with a mass concentration of 98%, first control the end point pH value to 0.5, react for 0.5 h, continue to add crude nickel-cobalt hydroxide to adjust the pH value back to 3.5, and carry out solid-liquid separation after reacting for 2 h to obtain an acid solution and an acid leaching residue. The mass dissolution rate of each component is as follows: Sc 95.10%, Y 94.83%, Ni 98.75%, Co 93.09%, Fe 0.24%, SiO2 40.04%. Add a PAM flocculant with a mass concentration of 0.5% to the acid solution, and the dosage of the flocculant is 1 L / m 3 acid solution, start stirring and mix evenly for 0.5 h, then let it stand and settle for 10 h, and carry out solid-liquid separation to obtain the silicon-removed solution. The silicon removal rate is 72.64%. After the silicon-removed solution is precisely filtered, the extraction stock solution is obtained;

[0039] (2) Solvent extraction: Prepare a composite extractant. The components and their volume percentages in the composite extractant are: P507 20%, TBP 5%, sulfonated kerosene 75%. Saponify the composite extractant with liquid alkali with a mass concentration of 30%, the saponification temperature is 35 °C, the saponification time is 15 min, and the saponification rate is 30%; then mix the saponified composite extractant with the extraction stock solution according to the phase ratio of 3:1 and carry out countercurrent extraction for 3 stages. The single-stage extraction time is 15 min and the temperature is 35 °C. After the extraction is completed, phase separation is carried out to obtain a loaded organic phase and a raffinate. The pH value of the raffinate is 3.5. The extraction rate of each component is as follows: Sc 94.89%, Y 94.07%, Ni <0.1%, Co 5.22%, Mn 8.35%, Fe 100%, Cu 5.99%, Zn 100%, Ca 24.70%;

[0040] (3) Washing: Using a 9 mol / L hydrochloric acid solution as the washing liquid, wash the loaded organic phase to remove iron, zinc, calcium, copper, and manganese, obtaining the first washing liquid and organic phase I; the washing phase ratio is 1:1, the washing temperature is 35 °C, the single-stage washing time is 15 min, the washing stage number is 2, and the hydrochloric acid concentration in the first washing liquid is 8 mol / L;

[0041] (4) Separation of scandium and yttrium: Using a washing liquid composed of a 4 mol / L hydrochloric acid solution and a 10% mass concentration oxalic acid solution with a volume ratio of 3:1, mix it with organic phase I. After washing and phase separation, preliminarily back-extract yttrium to obtain the second washing liquid and organic phase II; continue to use a yttrium back-extractant composed of a 6 mol / L hydrochloric acid solution and a 13% mass concentration oxalic acid solution with a volume ratio of 3:1, mix it with organic phase II. After washing and phase separation, deeply back-extract yttrium to obtain the third washing liquid and organic phase III; continue to use an 8 mol / L hydrochloric acid solution and an 18% mass concentration oxalic acid solution with a volume ratio of 3:1 as the scandium back-extractant, mix it with organic phase III, control the back-extraction temperature at 80 °C, the back-extraction time at 0.5 h. After back-extraction, separate the organic phase (phase separation) to obtain scandium oxalate precipitate; in the above process, control the washing / back-extraction phase ratio at 1:1, the temperature at 50 °C, the single-stage washing / back-extraction time at 15 min, the washing / back-extraction stage number at 2, the acidity in the second washing liquid at 3 mol / L, and the acidity in the third washing liquid at 5 mol / L;

[0042] (5) Wash the scandium oxalate precipitate with water, dry it, and calcine it to obtain high-purity scandium oxide. The purity of scandium oxide reaches 99.992%, and the impurity content meets the requirements of Sc2O3-4N in scandium oxide in GB / T 13219-2018 (see Table 1), with the yttrium content being 0.0006%; among them, the washing conditions are normal temperature washing, the water addition amount is based on a liquid-solid mass ratio of 2:1, the washing time is 1.5 h, the washing stage number is 1. After washing, perform solid-liquid separation to obtain the washed scandium oxalate and the washing liquid. The drying temperature of the washed scandium oxalate is 120 °C, the calcination temperature is 1000 °C, and the calcination time is 1 h;

[0043] (6) Heat the third washing liquid to 50 °C, add 10% mass concentration ammonia water to adjust the pH value to 2.0 for yttrium precipitation. The yttrium precipitation time is 2 h, keep it warm and age for 6 h. After aging, perform solid-liquid separation to obtain yttrium oxalate, wash yttrium oxalate with water, and calcine it at a high temperature. The calcination temperature is 1200 °C, and the calcination time is 1 h to obtain yttrium oxide. The purity of yttrium oxide reaches 99.91%, and the impurity content meets the requirements of Y2O3-3NC in yttrium oxide in GBT 3503-2015 (see Table 2), with the scandium content being 0.0018%.

[0044] Example 3

[0045] (1) Dissolution: 1000 kg of crude nickel cobalt hydroxide (main components are as follows: Sc 0.15 wt%, Y 0.059 wt%, Ni 42.39 wt%, Co 3.96 wt%, Fe 0.010 wt%, SiO2 0.32 wt%) is made into a slurry by adding water according to a liquid-solid mass ratio of 1.5:1. A concentrated nitric acid solution with a mass concentration of 60% is added. First, control the final pH value to be 1.2 and react for 0.5 h. Then, add crude nickel cobalt hydroxide to adjust the pH value back to 3.0 and react for 2 h, followed by solid-liquid separation to obtain an acid solution and an acid leaching residue. The mass dissolution rates of each component are as follows: Sc 92.24%, Y 92.00%, Ni 95.36%, Co 91.94%, Fe 0.21%, SiO2 35.96%. Add a PAM flocculant with a mass concentration of 0.3% to the acid solution. The dosage of the flocculant is 3 L / m 3 For the acid solution, start stirring and mix evenly for 0.5 h, then let it stand and settle for 1 h, followed by solid-liquid separation to obtain a silicon-removed solution. The silicon removal rate is 68.59%. After precision filtration, the silicon-removed solution is obtained as the extraction stock solution;

[0046] (2) Solvent extraction: Prepare a composite extractant. The components and their volume percentages in the composite extractant are: P507 15%, TBP 5%, sulfonated kerosene 80%. Saponify the composite extractant with ammonia water with a mass concentration of 15%. The saponification temperature is 45°C and the saponification time is 30 min, with a saponification rate of 100%. Mix the saponified composite extractant with the extraction stock solution according to a phase ratio of 2:1 and perform countercurrent extraction for 5 stages. The single-stage extraction time is 15 min and the temperature is 40°C. After extraction, phase separation is carried out to obtain a loaded organic phase and a raffinate. The pH value of the raffinate is 3.0. The extraction rates (mass) of each component are as follows: Sc 96.69%, Y 95.88%, Ni <0.1%, Co <0.1%, Mn <0.5%, Fe 100%, Cu 5.26%, Zn 100%, Ca 4.11%;

[0047] (3) Washing: Use an 8 mol / L hydrochloric acid solution as the washing liquid to wash the loaded organic phase to remove iron, zinc, calcium, copper, and manganese, obtaining a first washing liquid and organic phase I; the washing phase ratio is 1.5:1, the washing temperature is 50°C, the single-stage washing time is 10 min, and the washing stage number is 1. The hydrochloric acid concentration in the first washing liquid is 6.5 mol / L;

[0048] (4) Separation of scandium and yttrium: Using a washing solution consisting of a 3 mol / L hydrochloric acid solution and an 8% mass concentration oxalic acid solution with a volume ratio of 2:1, mix it with organic phase I. After the washing is completed, separate the phases to preliminarily back-extract yttrium, obtaining a second washing solution and organic phase II; continue to use a yttrium back-extractant consisting of a 5 mol / L hydrochloric acid solution and a 12% mass concentration oxalic acid solution with a volume ratio of 2:1, mix it with organic phase II. After the washing is completed, separate the phases to deeply back-extract yttrium, obtaining a third washing solution and organic phase III; continue to use a scandium back-extractant consisting of a 7 mol / L hydrochloric acid solution and a 16% mass concentration aqueous oxalic acid solution with a volume ratio of 2:1, mix it with organic phase III, control the back-extraction temperature at 60 °C, the back-extraction time at 1 h. After the back-extraction is completed, separate the organic phase (phase separation) to obtain scandium oxalate precipitate; in the above washing process, control the washing / back-extraction ratio at 1.5:1, the temperature at 30 °C, the single-stage washing / back-extraction time at 10 min, the washing / back-extraction stage at 1 stage, the acidity of the second washing solution at 3 mol / L, and the acidity of the third washing solution at 5 mol / L;

[0049] (5) Wash the scandium oxalate precipitate with water, dry it, and calcine it to obtain high-purity scandium oxide. The purity of the scandium oxide reaches 99.993%, and the impurity content meets the requirements of Sc2O3-4N in scandium oxide in GB / T 13219-2018 (see Table 1), with the yttrium content being 0.0007%; among them, the washing conditions are normal temperature washing, the water addition amount is based on a liquid-solid mass ratio of 3:1, the washing time is 1 h, the washing stage is 1 stage. After the washing is completed, separate the solid and liquid to obtain washed scandium oxalate and the washing solution. The drying temperature of the washed scandium oxalate is 100 °C, the calcination temperature is 1200 °C, and the calcination time is 2 h;

[0050] (6) Heat the third washing solution to 60 °C, add 5% mass concentration ammonia water to adjust the pH value to 2.5 for yttrium precipitation. The yttrium precipitation time is 1.5 h, keep it warm and age for 4 h. After the aging is completed, separate the solid and liquid to obtain yttrium oxalate. Wash the yttrium oxalate with water and calcine it at a high temperature. The calcination temperature is 1000 °C, and the calcination time is 2 h to obtain yttrium oxide. The purity of the yttrium oxide reaches 99.93%, and the impurity content meets the requirements of Y2O3-3NC in yttrium oxide in GBT 3503-2015 (see Table 2), with the scandium content being 0.0020%.

[0051] Example 4

[0052] (1) Dissolution: 100 kg of crude nickel cobalt hydroxide (main components are as follows: Sc 0.076 wt%, Y 0.012 wt%, Ni 43.00 wt%, Co 3.77 wt%, Fe 0.90 wt%, SiO2 1.42 wt%) is pulped with water according to a liquid-solid mass ratio of 1.5:1, and a concentrated hydrochloric acid solution with a mass concentration of 30% is added. First, control the end-point pH to 1.0 and react for 1 h. Then, add crude nickel cobalt hydroxide again to adjust the pH value to 3.0 and react for 4 h, followed by solid-liquid separation to obtain an acid solution and an acid leaching residue. The mass dissolution rates of each component are as follows: Sc 91.24%, Y 92.78%, Ni 96.36%, Co 92.41%, Fe 0.20%, SiO2 38.04%. Add a PAM flocculant with a mass concentration of 0.3% to the acid solution, and the dosage of the flocculant is 3 L / m 3 acid solution. After starting stirring and mixing evenly for 0.5 h, then let it stand and settle for 1 h, followed by solid-liquid separation to obtain a silicon-removed solution. The silicon removal rate is 70.12%. The silicon-removed solution is obtained as the extraction feed solution after precision filtration.

[0053] (2) Solvent extraction: Prepare a composite extractant. The components and their volume percentages in the composite extractant are: P507 15%, sulfonated kerosene 85%. Saponify the composite extractant with ammonia water with a mass concentration of 10%. The saponification temperature is 40 °C, the saponification time is 20 min, and the saponification rate is 50%. Mix the saponified composite extractant with the extraction feed solution according to a phase ratio of 2:1 and perform countercurrent extraction for 4 stages. The single-stage extraction time is 10 min, and the temperature is 50 °C. After extraction, phase separation is carried out to obtain a loaded organic phase and a raffinate. The pH value of the raffinate is 3.0. The extraction rates (mass) of each component are as follows: Sc 96.80%, Y 95.42%, Ni <0.1%, Co <0.1%, Mn <0.5%, Fe 100%, Cu 5.00%, Zn 100%, Ca 4.25%.

[0054] (3) Washing: Use an 8 mol / L hydrochloric acid solution as the washing liquid to wash the loaded organic phase to remove iron, zinc, calcium, copper, and manganese, obtaining a first washing liquid and organic phase I; the washing phase ratio is 2:1, the washing temperature is 50 °C, the single-stage washing time is 10 min, and the number of washing stages is 2. The hydrochloric acid concentration in the first washing liquid is 6 mol / L;

[0055] (4) Separation of scandium and yttrium: Using a washing solution of 3 mol / L hydrochloric acid and 8% mass concentration oxalic acid solution with a volume ratio of 2:1, mixing it with organic phase I, separating the phases after washing, preliminarily back-extracting yttrium to obtain the second washing solution and organic phase II; continuing to use a yttrium back-extraction solution of 5 mol / L hydrochloric acid and 12% mass concentration oxalic acid solution with a volume ratio of 2:1, mixing it with organic phase II, separating the phases after washing, deeply back-extracting yttrium to obtain the third washing solution and organic phase III; continuing to use a scandium back-extraction agent of 7 mol / L hydrochloric acid and 16% mass concentration oxalic acid solution with a volume ratio of 2:1, mixing it with organic phase III, controlling the back-extraction temperature at 60 °C, separating the organic phase (phase separation) to obtain scandium oxalate precipitate; the above process controls the washing / back-extraction phase ratio at 2:1, the temperature at 30 °C, the single-stage / back-extraction washing time at 10 min, the washing / back-extraction stage number at 2 stages, the acidity of the second washing solution at 2 mol / L, and the acidity of the third washing solution at 4 mol / L;

[0056] (5) Wash the scandium oxalate precipitate with water, dry it, and calcine it to obtain high-purity scandium oxide. The purity of scandium oxide reaches 99.993%, and the impurity content meets the requirements of Sc2O3-4N in GB / T 13219-2018 scandium oxide (see Table 1), with the yttrium content being 0.0009%; among them, the washing conditions are normal temperature washing, the water addition amount is in accordance with a liquid-solid mass ratio of 3:1, the washing time is 1 h, the washing stage number is 1 stage. After washing, solid-liquid separation is carried out to obtain the washed scandium oxalate and the washing solution. The drying temperature of the washed scandium oxalate is 100 °C, the calcination temperature is 1200 °C, and the calcination time is 2 h;

[0057] (6) Heat the third washing solution to 60 °C, add 5% mass concentration ammonia water to adjust the pH value to 2.5 for yttrium precipitation. The yttrium precipitation time is 1.5 h, keep it warm and age for 4 h. After aging, solid-liquid separation is carried out to obtain yttrium oxalate. Wash yttrium oxalate with water and calcine it at a high temperature. The calcination temperature is 1000 °C, and the calcination time is 2 h to obtain yttrium oxide. The purity of yttrium oxide reaches 99.95%, and the impurity content meets the requirements of Y2O3-3NC in GBT 3503-2015 yttrium oxide (see Table 2), with the scandium content being 0.0022%.

[0058] Table 1 GB / T 13219-2018 Sc2O3-4N indicators

[0059]

[0060] Table 2 GB / T 3503-2015 Y2O3-3NC indicators

[0061]

[0062] The above description is a detailed description of the preferred and feasible embodiments of the present invention. However, the embodiments are not intended to limit the scope of the patent application of the present invention. Any equivalent changes or modifications made under the technical spirit disclosed by the present invention shall fall within the scope of the patent covered by the present invention.

Claims

1. A method for separating scandium and yttrium from crude nickel cobalt hydroxide, characterized in that, It includes the following steps: (1) Dissolution: Pulverize crude nickel cobalt hydroxide with water, add inorganic acid, control the final pH value to be 0.5 - 1.5, react, continue to add crude nickel cobalt hydroxide to adjust the pH value back to 2.5 - 3.5, separate the solid and liquid after reaction to obtain an acid solution and acid leaching residue. The acid solution is subjected to flocculation for silicon removal, static sedimentation, and then solid-liquid separation to obtain the silicon-removed solution. The silicon-removed solution is subjected to precision filtration to obtain the original extraction solution; (2) Solvent extraction: Mix the composite extractant with the original extraction solution for extraction to obtain a loaded organic phase and a raffinate; (3) Washing: Use a hydrochloric acid solution with a concentration of 8 - 10 mol / L as the washing solution to wash the loaded organic phase to obtain the first washing solution and organic phase I; (4) Separation of scandium and yttrium: Use a hydrochloric acid solution with a concentration of 2 - 4 mol / L and an oxalic acid solution with a mass concentration of 5 - 10% as the washing solution, mix with organic phase I, and preliminarily back-extract yttrium to obtain the second washing solution and organic phase II; continue to use a hydrochloric acid solution with a concentration of 4 - 6 mol / L and an oxalic acid solution with a mass concentration of 11 - 13% as the yttrium back-extractant, mix with organic phase II, and deeply back-extract yttrium to obtain the third washing solution and organic phase III; continue to use a hydrochloric acid solution with a concentration of 6 - 8 mol / L and an oxalic acid solution with a mass concentration of 15 - 18% as the scandium back-extractant, mix with organic phase III, control the back-extraction temperature to be 40 - 80°C, separate the organic phase to obtain scandium oxalate precipitate; (5) Wash, dry, and calcine the scandium oxalate precipitate to obtain high-purity scandium oxide; (6) Heat the third washing solution, adjust the pH value to 1.5 - 2.5, perform yttrium precipitation, keep warm and age, separate the solid and liquid, wash the yttrium oxalate with water, and calcine to obtain yttrium oxide; The components and volume ratios in the composite extractant are as follows: 10 - 20% of P507, 0 - 10% of the modifier, and 75 - 85% of the diluent; The saponification rate of P507 is 0 - 100%, the modifier is tributyl phosphate, and the diluent is sulfonated kerosene.

2. The method for separating scandium and yttrium from crude nickel cobalt hydroxide according to claim 1, characterized in that: In the step (1), pulverize crude nickel cobalt hydroxide with water, add inorganic acid, control the final pH value to be 0.5 - 1.5, react for 0.5 - 1 h, continue to add crude nickel cobalt hydroxide to adjust the pH value back to 2.5 - 3.5, separate the solid and liquid after reacting for 1 - 4 h to obtain an acid solution and acid leaching residue.

3. The method for separating scandium and yttrium from crude nickel cobalt hydroxide as claimed in claim 1, wherein: In the step (1), the flocculant used for silicon removal by flocculation is polyacrylamide with a mass concentration of 0.1% - 0.5%, and the addition amount of the flocculant is 1 - 5 L / m 3 acid solution, and the static sedimentation time is 0.5 - 10 h.

4. The method for separating scandium and yttrium from crude nickel cobalt hydroxide according to claim 1, characterized in that: In the step (2), the ratio of the composite extractant to the original extraction solution is 1 - 3:1, and the pH value of the raffinate is controlled at 2.5 - 3.

5.

5. The method for separating scandium and yttrium from crude nickel cobalt hydroxide as claimed in claim 1, wherein: In the step (3), the washing ratio is 0.5 - 2:1, and the hydrochloric acid concentration in the first washing solution is controlled at 6 - 9.5 mol / L.

6. The method for separating scandium and yttrium from crude nickel cobalt hydroxide as claimed in claim 1, wherein: In the step (4), the volume ratios of the hydrochloric acid solution and the oxalic acid solution are both 1 - 3:

1.

7. The method for separating scandium and yttrium from crude nickel cobalt hydroxide as claimed in claim 1, wherein: In the step (4), control the acidity in the second washing solution to be 2 - 4 mol / L, the acidity in the third washing solution to be 4 - 6 mol / L, and the washing and back-extraction ratios are both 0.5 - 2:

1.

8. The method for separating scandium and yttrium from crude nickel cobalt hydroxide according to claim 1, characterized in that: The step (6) is specifically as follows: Heat the third washing solution to 40 - 60°C, adjust the pH value to 1.5 - 2.5, perform yttrium precipitation for 1 - 2 h, keep warm and age for 3 - 6 h, separate the solid and liquid to obtain yttrium oxalate, wash the yttrium oxalate with water, and calcine at 800 - 1200°C for 1 - 3 h to obtain yttrium oxide.

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