Selective leaching method for scandium in scandium-containing mineral

Abstract

The invention belongs to the field of mineral treatment, and particularly relates to a selective leaching method for scandium in a scandium-containing mineral, which comprises the following steps: roasting the scandium-containing mineral and an additive to obtain a roasted material, and mixing the roasted material with a leaching agent for leaching to obtain a scandium-rich leachate; the additive is an inorganic salt of at least one cation of sodium, calcium, potassium and ammonium; the leaching agent comprises an aqueous solution of a component A and an aqueous solution of a component B, wherein the component A is a C2-C10 water-soluble binary or above carboxylic acid compound; the component B is a water-soluble salt of the component A; the molar ratio of the component A to the component B is 1: (0.5-5); and the concentration of the component A in the leaching agent is 1-15 mol / L. According to the method, the scandium-containing mineral is roasted and modified through the additive, and then the scandium-containing mineral is leached through the buffer system containing the component A and the component B, so that synergy can be achieved, and scandium in the scandium-containing mineral can be selectively and efficiently extracted.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of processing of natural mineral resources, and particularly relates to the field of processing of scandium-containing minerals. BACKGROUND

[0002] Scandium is an important rare earth element with excellent physical and chemical properties, and is widely used in the fields of aerospace, electronics, chemical industry, etc. However, scandium exists in the form of associated ore in nature, with low grade and high extraction difficulty.

[0003] Scandium-containing minerals are mainly natural scandium-containing minerals and their derived tailings, such as scandium-containing bauxite, laterite nickel ore, titanium ore, Bayan Obo ore and their tailings after processing, which are typical associated carriers of scandium in nature. Such materials are different from other secondary resources containing scandium (such as red mud), and the occurrence state of scandium is complex and highly encapsulated. For example, scandium in natural scandium-containing minerals is mainly embedded in silicate and oxide lattices in the form of isomorphism (such as rare earth-scandium coexisting silicate structure in Bayan Obo ore). In addition, the grade of scandium in natural minerals is usually low, and scandium is highly associated with impurity elements such as iron, titanium, rare earth, calcium and magnesium. The selective recovery of scandium in such scandium-containing minerals is difficult.

[0004] At present, the method for extracting scandium from scandium-containing minerals mainly adopts inorganic acid leaching, such as hydrochloric acid and sulfuric acid. For example, the patent document with publication number CN117385207A discloses a method for recovering scandium from iron separation tailings of ultra-lean vanadium-titanium magnetite, which specifically records that the ultra-lean vanadium-titanium magnetite is ground to obtain a sample with a particle size of less than 0.074 mm; the sample is mixed with sodium hydroxide and calcined to obtain a calcined material; the calcined material is mixed with a sulfuric acid solution and leached under stirring to obtain a leaching solution. In addition, the patent document with publication number RU2806940C1 also reports a method for treating scandium-containing raw materials with sulfuric acid.

[0005] In summary, there are many problems in the existing process of leaching scandium from scandium ore with inorganic acid: on the one hand, inorganic acid has strong corrosiveness, which requires high equipment and increases production cost; on the other hand, the selectivity of inorganic acid leaching is poor, which will leach other impurity elements in the ore at the same time, leading to increased difficulty in subsequent separation and purification, affecting the extraction efficiency and purity of scandium.

[0006] Therefore, it is of great practical significance to develop an efficient, green and economical method for extracting scandium, which solves the problems of strong equipment corrosion and poor selectivity in traditional inorganic acid leaching method. SUMMARY

[0007] In view of the problem of difficult selective extraction of scandium from scandium-containing minerals, the present application aims to provide a method for selectively leaching scandium from scandium-containing minerals, which aims to improve the extraction rate and selectivity of scandium.

[0008] Scandium in natural scandium-bearing minerals is of low grade and often deeply embedded with numerous impurities, making selective extraction difficult. To address this problem, this invention provides the following improvement:

[0009] A selective leaching method for scandium in scandium-containing minerals involves roasting the scandium-containing minerals and additives to obtain roasted material, mixing the roasted material with a leaching agent, and then performing a leaching process to obtain a scandium-rich leachate.

[0010] The additive is an inorganic salt of at least one cation selected from sodium, calcium, potassium, and ammonium;

[0011] The leaching agent comprises an aqueous solution of component A and component B; wherein, component A is C2~C 10 Water-soluble dicarboxylic acid compounds; component B is a water-soluble salt of component A;

[0012] The molar ratio of component A to component B is 1:0.5~5; the concentration of component A in the leachate is 1~15 mol / L.

[0013] To address the challenge of selectively extracting scandium from scandium-containing minerals, this invention innovatively modifies scandium-containing minerals by roasting with additives, followed by leaching using a buffer system containing component A and component B. Furthermore, by jointly controlling the proportion and concentration of component A and component B in the additives and leaching agent, a synergistic effect can be achieved, enabling selective and efficient extraction of scandium from scandium-containing minerals.

[0014] The scandium-bearing minerals mentioned are natural scandium-bearing minerals. Compared with other scandium-bearing secondary solid wastes, they present more complex natural embedded structures, more complex types of impurities, and denser mineral structures, posing greater processing challenges. For example, the scandium is isomorphously embedded in at least one lattice of silicates (such as aegirine and pyroxene) and oxides (such as ilmenite and hematite), forming Scandium (Sc). 3+ With non-Sc impurity elements (such as Fe) 3+ Al 3+ Ti 4+ A substitutional symbiotic structure of isocations.

[0015] Furthermore, in the scandium-containing minerals, the non-Sc impurity elements include at least one selected from iron, titanium, silicon, aluminum, calcium, magnesium, and rare earth elements. Even further, the non-Sc impurity elements include at least iron and titanium, and selectively include at least one impurity element selected from silicon, aluminum, calcium, magnesium, and rare earth elements.

[0016] The scandium-bearing minerals are concentrates or tailings of scandium-bearing natural minerals, including at least one of scandium-bearing bauxite, laterite, titanium ore, and Bayan Obo ore.

[0017] In the present application, the content of scandium in the scandium-containing mineral is not particularly required, and theoretically, the higher the content, the more conducive to extraction.

[0018] In the present application, thanks to the selective leaching scheme of the present application, it also has excellent selective extraction effect for low-grade scandium-containing minerals. For example, studies have shown that the scandium content of the scandium-containing mineral of the present application can be as low as 100-1000 ppm, and further can be 600-800 ppm.

[0019] In the present application, the other impurity components and contents in the scandium-containing mineral are also not particularly required, for example, as an exemplary scheme, it includes components such as niobium, rare earth, iron, scandium, titanium, etc., wherein the TFe content is 30±10%, the Ti content is 15±5%, the Nb2O5 content is 5±2%, the Si content is 11±5%, the Ca content is 5±2%, and the Mg content is 2±1%. Further, the TFe content is 30±3%, the Ti content is 15±1%, the Nb2O5 content is 5±0.5%, the Si content is 11±2%, the Ca content is 5±0.5%, and the Mg content is 2±0.5%.

[0020] The additive includes at least one of a carbonate salt and a sulfate salt of the cation.

[0021] The additive includes an additive A and an additive B, wherein the additive A is an inorganic salt of at least one of sodium, potassium, and ammonium cations; and the additive B is an inorganic salt of calcium.

[0022] The present application researches and finds that for the difficult-to-handle object, the additive A and the additive B are used innovatively to further realize synergy, improve the leaching effect of Sc, and improve the selectivity of Sc and impurities.

[0023] Preferably, the weight ratio of the additive A to the additive B in the additive is 1:0.5-2.

[0024] Preferably, the weight ratio of the scandium-containing mineral to the additive is 1:0.05-0.5, further can be 1:0.15-0.35, and further can be 1:0.2-0.3.

[0025] In the present application, the atmosphere of roasting can be an oxygen-containing atmosphere, and further can be air in consideration of process simplicity.

[0026] In the present application, the temperature of the roasting process is 500-1000°C, further can be 700-950°C, and further can be 750-900°C.

[0027] In the present application, the roasting time is 0.5-5h, and further can be 2-4h.

[0028] In the present application, the component A includes at least one of citric acid, oxalic acid, tartaric acid, malonic acid and ethylenediaminetetraacetic acid.

[0029] In the present application, the component B is at least one of sodium salt, potassium salt and ammonium salt of the component A.

[0030] In the present application, the additive assisted roasting can modify the Sc-containing mineral, and the mild buffer system constructed by the component A and the component B can be used for leaching, so that the efficient leaching of Sc can be realized, and the selective separation effect of Sc and Fe, Ti, Ca, Mg, Al and Si can be improved.

[0031] In the present application, the component A is at least one of citric acid, oxalic acid and tartaric acid.

[0032] In the present application, the molar ratio of the component A to the component B is preferably 1:0.7-1.5, and further preferably 1:0.8-1.2.

[0033] In the present application, the concentration of the component A in the leaching agent can be 1-5M, and further can be 1.5-2.5M.

[0034] In the present application, the liquid-solid ratio of the leaching process is 2-15mL / g, and further can be 8-12mL / g.

[0035] In the present application, the temperature of the leaching stage is 30-180℃, and considering the operation and cost, can be further 70-95℃.

[0036] The leaching time is 0.5-12h, and considering the processing efficiency, can be further 1-3h.

[0037] Beneficial effects

[0038] In the present application, the additive is used for selectively modifying the Sc-containing mineral, so that the activation of Sc in the raw ore and the beneficial transformation of other impurities can be realized, and the special ratio and concentration of the component A-component B buffer leaching system are further combined and controlled, so that the high selective leaching of Sc can be realized based on the selective coordination ability of the anion of the component A-component B to Sc, and the accompanied leaching of Fe, Ti, Ca, Mg, Al and Si can be significantly reduced, and the leaching selectivity of Sc is improved.

[0039] The research of the present application also shows that the roasting modification using the additive combination of the additive A and the additive B is expected to be combined with the buffer leaching system constructed by the component A and the component B, so as to further strengthen the leaching rate and selectivity of Sc.

[0040] The present application can be carried out under low acidity, which reduces the corrosion of the equipment, reduces the equipment investment and maintenance cost, and realizes green and economic leaching. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1 SEM image of the scandium-containing mineral raw material (Baiyunebo ore) of Example 1;

[0042] Figure 2 SEM image of the leaching residue of Example 2. DETAILED DESCRIPTION

[0043] The present application will be further described in detail below in combination with specific examples.

[0044] The scandium-containing mineral is selected in the example, wherein scandium is mainly contained in silicates (such as aegirine and pyroxene) and iron and titanium oxides. The scandium-containing mineral has a low scandium grade (<400 ppm); the scandium is in a complex state and is difficult to extract (is deeply embedded in the crystal lattices of ilmenite, hematite, silicate and other stable oxides in the form of isomorphism); the mineral is finely disseminated and has a complex composition, and the scandium extraction effect is poor.

[0045] As an illustrative scheme, in the following cases, the scandium-containing mineral is Baiyunebo ore, and the valuable elements include niobium, rare earth, iron, scandium, titanium and the like, wherein the content of TFe is 30 wt.%, the content of Ti is 15 wt.%, the content of Nb2O5 is 5 wt.%, the content of Si is 11 wt.%, the content of Ca is 5 wt.%, the content of Mg is 2 wt.%, and the content of scandium is 700 ppm; the main minerals include hematite, aegirine, ilmenite, calcite and bastnaesite.

[0046] In the present application, the atmosphere of the roasting can be a conventional air atmosphere.

[0047] Example 1

[0048] (1) Roasting: the Baiyunebo ore is mixed with the additive (sodium carbonate) at a mass ratio of 1:0.2, and is roasted at 800℃ for 3h.

[0049] (2) Acid leaching: the roasting product of step (1) is added to the component A (citric acid)-component B (sodium citrate salt) solution (leaching agent solution) and is leached at 90℃ for 2h;

[0050] In the leaching agent solution, the molar ratio of citric acid to sodium citrate is 1:1, the concentration of citric acid is 2 mol / L, and the liquid-solid ratio of the leaching agent solution to the calcined product is 10:1 (mL / g).

[0051] (3) Separation: The leaching slurry from step (2) is filtered to obtain leaching residue and leaching solution.

[0052] The leaching rates were as follows: scandium 95.5%, iron 60%, titanium 41%, calcium 30%, silicon 32%, and magnesium and aluminum less than 10%.

[0053] Example 2

[0054] Compared with Example 1, the only difference is that in step (1), the type of additive is changed, and the experimental groups are as follows:

[0055] Group A: The additive is sodium sulfate;

[0056] Group B: The additive is calcium carbonate;

[0057] Group C: The additives are sodium sulfate and calcium carbonate in a weight ratio of 1:1;

[0058] The dosage of additives and other operating conditions in each group were the same as in Example 1.

[0059] Group A: According to the test results, the leaching rates of scandium, iron, titanium, calcium, silicon, magnesium, and aluminum were all less than 20%.

[0060] Group B: According to the test results, the leaching rates of scandium were 81%, iron 18%, titanium 20%, calcium 25%, silicon 18%, and magnesium and aluminum were both less than 20%.

[0061] Group C: According to the test results, the leaching rate of scandium was 96%, the leaching rate of iron was 15%, the leaching rate of titanium was 16%, the leaching rate of calcium was 20%, the leaching rate of silicon was 15%, and the leaching rates of magnesium and aluminum were both less than 10%.

[0062] As demonstrated in Examples 1 and 2, the use of a combination of sodium sulfate and calcium carbonate as additives helps to further achieve synergy and improve the leaching rate and selectivity of scandium.

[0063] Example 3

[0064] Compared with Example 1, the only difference is that the ratio of component A to component B in step (2) is changed. The experimental group is as follows:

[0065] Group A: In the leaching agent solution, the molar ratio of citric acid to sodium citrate is 1:0.8, and the total solute in the leaching agent and other operating conditions remain unchanged.

[0066] The leaching rates were as follows: scandium 96.2%, iron 55%, titanium 38%, calcium 28%, silicon 30%, and magnesium and aluminum less than 10%.

[0067] Comparative Group A: In the leaching agent solution, the molar ratio of citric acid to sodium citrate is 1:0.3, and the total solute in the leaching agent remains unchanged under other operating conditions.

[0068] The leaching rates were as follows: scandium 50%, iron 45%, titanium 32%, calcium 34%, silicon 35%, and magnesium and aluminum less than 10%.

[0069] Example 4

[0070] Compared with Example 1, the only difference is that the operating conditions are changed, and the steps are different.

[0071] (1) Calcination: Mix the Bayan Obo mineral with the additive (sodium carbonate) at a mass ratio of 1:0.3 and calcine at 900℃ for 2 hours.

[0072] (2) Acid leaching: The roasted product from step (1) is added to a citric acid-sodium citrate solution (leaching agent solution) and leached at 85°C for 2.5 h;

[0073] In the leaching agent solution, the molar ratio of citric acid to sodium citrate is 1:0.9, the concentration of citric acid is 1.5 mol / L, and the liquid-solid ratio of the leaching agent solution to the calcined product is 8:1 (mL / g).

[0074] (3) Separation: The leaching slurry from step (2) is filtered to obtain leaching residue and leaching solution.

[0075] The leaching rates were as follows: scandium 97.2%, iron 57%, titanium 43%, calcium 32%, silicon 29%, and magnesium and aluminum less than 10%.

[0076] Example 5

[0077] Compared to Example 1, the only difference is that the operating conditions are changed, and the difference lies in changing the types of component A and component B in step 2:

[0078] (2) Acid leaching: The roasted product from step (1) is added to an oxalic acid-ammonium oxalate solution (leaching agent solution) and leached at 85°C for 2.5 h; in the leaching agent solution, the molar ratio and concentration of component A and component B remain unchanged, and the solid-liquid ratio of the leaching solution remains unchanged.

[0079] The leaching rates were as follows: scandium 95.2%, iron 61%, titanium 42%, calcium 31%, silicon 20%, and magnesium and aluminum less than 10%.

[0080] Comparative Example 1

[0081] Compared with Example 1, the only difference is that in step (2), the concentration of the solute in the leaching agent solution hydrochloric acid solution is the same as that in the leaching agent solution of Example 1, and the other operations and parameters are the same as those in Example 1.

[0082] The leaching rates were as follows: scandium 74%, iron 72%, titanium 51%, calcium 42%, silicon 35%, magnesium 35%, and aluminum 30%.

[0083] Comparative Example 2

[0084] Compared with Comparative Example 1, the only difference is that step (1) is not performed. Instead, the Bayan Obo ore is directly subjected to hydrochloric acid leaching in step (2) and subsequent treatment. All other operations and parameters are the same as in Example 1.

[0085] The leaching rates were as follows: scandium 11%, iron 22%, titanium 9%, calcium 12%, silicon 25%, magnesium 21%, and aluminum 15%.

[0086] Comparative Example 3

[0087] Compared with Example 1, the only difference is that step (1) is omitted, and the Bayan Obo mine is directly subjected to step (2) and subsequent processing. All other operations and parameters are the same as in Example 1.

[0088] The leaching rates were as follows: scandium 11%, iron 12%, titanium 5%, calcium 4%, silicon 3%, magnesium 7%, and aluminum 3%.

[0089] Comparative Example 4

[0090] Compared with Example 1, the only difference is that in step (2), component B is missing in the leachate, and the missing component B is supplemented by component A in equimolar amounts. All other operations and parameters are the same as in Example 1.

[0091] The leaching rates were as follows: scandium 61%, iron 62%, titanium 51%, calcium 42%, silicon 35%, magnesium 41%, and aluminum 35%.

[0092] Comparative Example 5

[0093] Compared with Example 1, the only difference is that in step (2), component A is missing in the leachate, and the missing component A is supplemented by component B in equimolar form. All other operations and parameters are the same as in Example 1.

[0094] The leaching rates were as follows: scandium 31%, iron 22%, titanium 21%, calcium 12%, silicon 5%, magnesium 11%, and aluminum 3%.

[0095] Comparative Example 6

[0096] Compared with Example 1, the only difference is that in step (2), an equimolar amount of sodium chloride is used to replace component B; all other operations and parameters are the same as in Example 1.

[0097] The leaching rates were as follows: scandium 35.5%, iron 38%, titanium 21%, calcium 18%, silicon 18%, and magnesium and aluminum less than 10%.

[0098] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for selective leaching of scandium from scandium-containing minerals, characterized in that, The scandium-containing minerals and additives are roasted to obtain roasted material. The roasted material is then mixed with a leaching agent and leached to obtain scandium-rich leachate. The additive is an inorganic salt of at least one cation selected from sodium, calcium, potassium, and ammonium; The leaching agent comprises an aqueous solution of component A and component B; wherein, component A is C2~C 10 Water-soluble dicarboxylic acid compounds; component B is a water-soluble salt of component A; The molar ratio of component A to component B is 1:0.5~5; the concentration of component A in the leachate is 1~15 mol / L.

2. The selective leaching method for scandium in scandium-containing minerals as described in claim 1, characterized in that, The scandium-bearing minerals mentioned are natural scandium-bearing minerals, in which scandium is embedded in at least one lattice of silicates or oxides in an isomorphic manner, forming Sc 3+ Substitutional symbiotic structure with non-Sc impurity elements; In the scandium-containing minerals, the non-Sc impurity elements include at least one of iron, titanium, silicon, aluminum, calcium, magnesium, and rare earth elements; The scandium-bearing minerals mentioned are concentrates or tailings of scandium-bearing natural minerals, including at least one of scandium-bearing bauxite, laterite nickel ore, titanium ore, and Bayan Obo ore.

3. The selective leaching method for scandium in scandium-containing minerals as described in claim 1, characterized in that, The additives include at least one of the carbonates and sulfates of the cation.

4. The selective leaching method for scandium in scandium-containing minerals as described in claim 3, characterized in that, The additives include additive A and additive B, wherein additive A is an inorganic salt of at least one cation selected from sodium, potassium, and ammonium; and additive B is an inorganic salt of calcium. In the additives mentioned above, the weight ratio of additive A to additive B is 1:0.5~2.

5. The selective leaching method for scandium in scandium-containing minerals as described in claim 1, 3, or 4, characterized in that, The weight ratio of scandium-containing minerals to additives is 1:0.05~0.5; The roasting process is carried out at a temperature of 500~1000℃; The roasting time is 0.5~5 hours.

6. The selective leaching method for scandium in scandium-containing minerals as described in claim 1, characterized in that, In the leaching agent, component A includes at least one of citric acid, oxalic acid, tartaric acid, malonic acid, and ethylenediaminetetraacetic acid.

7. The selective leaching method for scandium in scandium-containing minerals as described in claim 6, characterized in that, Component B is at least one of the sodium salt, potassium salt, and ammonium salt of component A.

8. The selective leaching method for scandium in scandium-containing minerals as described in claim 1, 6, or 7, characterized in that, The molar ratio of component A to component B is 1:0.7~1.

5.

9. The selective leaching method for scandium in scandium-containing minerals as described in claim 1, characterized in that, The liquid-to-solid ratio during the leaching process is 2~15 mL / g.

10. The selective leaching method for scandium in scandium-containing minerals as described in claim 1, characterized in that, The leaching temperature is 30~180℃; The leaching time is 0.5~12h.

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