Method for selective leaching of scandium from scandium-containing minerals

Abstract

This invention belongs to the field of mineral processing, specifically relating to a selective leaching method for scandium in scandium-containing minerals. The method involves calcining the scandium-containing minerals and an additive to obtain a calcined material, then mixing the calcined material with a leaching agent for leaching to obtain a 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~C6. 10 The present invention describes a water-soluble binary or higher carboxylic acid compound; 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 leaching agent is 1~15 mol / L. The present invention modifies scandium-containing minerals by calcination with additives, and then uses a buffer system containing components A and B for leaching. This achieves synergistic effects, enabling selective and efficient extraction of scandium from scandium-containing minerals.

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 iron separation tailings are 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 described in 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 illustrative 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] The molar ratio of citric acid to sodium citrate in the leaching agent solution 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 of step (2) is filtered to obtain leaching residue and leaching solution.

[0052] It is detected that the leaching rate of scandium is 95.5%, the leaching rate of iron is 60%, the leaching rate of titanium is 41%, the leaching rate of calcium is 30%, the leaching rate of silicon is 32%, and the leaching rates of magnesium and aluminum are both 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 respectively:

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

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

[0057] Group C: the additive is sodium sulfate and calcium carbonate with a weight ratio of 1:1;

[0058] The amount of additive in each group and other operating conditions are the same as those in Example 1.

[0059] Group A: it is detected that the leaching rate of scandium is 92%, the leaching rate of iron is 62%, the leaching rate of titanium is 51%, the leaching rate of calcium is 25%, the leaching rate of silicon is 28%, and the leaching rates of magnesium and aluminum are both less than 20%.

[0060] Group B: it is detected that the leaching rate of scandium is 81%, the leaching rate of iron is 18%, the leaching rate of titanium is 20%, the leaching rate of calcium is 25%, the leaching rate of silicon is 18%, and the leaching rates of magnesium and aluminum are both less than 20%.

[0061] Group C: it is detected that the leaching rate of scandium is 96%, the leaching rate of iron is 15%, the leaching rate of titanium is 16%, the leaching rate of calcium is 20%, the leaching rate of silicon is 15%, and the leaching rates of magnesium and aluminum are both less than 10%.

[0062] From Examples 1 and 2, it can be seen that the additive of sodium sulfate and calcium carbonate combined helps to further achieve synergy and further 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, and the experimental groups are:

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

[0066] The leaching rate of scandium was 96.2%, the leaching rate of iron was 55%, the leaching rate of titanium was 38%, the leaching rate of calcium was 28%, the leaching rate of silicon was 30%, and the leaching rate of magnesium and aluminum was less than 10%.

[0067] Comparative group A: the molar ratio of citric acid to sodium citrate in the leaching agent solution was 1:0.3, and the total solute in the leaching agent remained unchanged, and the other operating conditions remained unchanged.

[0068] The leaching rate of scandium was 50%, the leaching rate of iron was 45%, the leaching rate of titanium was 32%, the leaching rate of calcium was 34%, the leaching rate of silicon was 35%, and the leaching rate of magnesium and aluminum was less than 10%.

[0069] Example 4

[0070] Compared with Example 1, the difference is only that the operating conditions are changed, and the difference is that the type of component A and component B in step 2 is changed.

[0071] (1) Roasting: the Baiyunebo ore was mixed with the additive (sodium carbonate) at a mass ratio of 1:0.3 and roasted at 900°C for 2h.

[0072] (2) Acid leaching: the roasting product of step (1) was added to a citric acid-sodium citrate salt solution (leaching agent solution) and leached at 85°C for 2.5h;

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

[0074] (3) Separation: the leaching slurry of step (2) was filtered to obtain leaching residue and leaching solution.

[0075] The leaching rate of scandium was 97.2%, the leaching rate of iron was 57%, the leaching rate of titanium was 43%, the leaching rate of calcium was 32%, the leaching rate of silicon was 29%, and the leaching rate of magnesium and aluminum was less than 10%.

[0076] Example 5

[0077] Compared with Example 1, the difference is only that the operating conditions are changed, and the difference is that the type of component A and component B in step 2 is changed.

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

[0079] The detection shows that the leaching rate of scandium is 95.2%, the leaching rate of iron is 61%, the leaching rate of titanium is 42%, the leaching rate of calcium is 31%, the leaching rate of silicon is 20%, and the leaching rate of magnesium and aluminum is less than 10%.

[0080] Comparative Example 1

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

[0082] The detection shows that the leaching rate of scandium is 74%, the leaching rate of iron is 72%, the leaching rate of titanium is 51%, the leaching rate of calcium is 42%, the leaching rate of silicon is 35%, the leaching rate of magnesium is 35%, and the leaching rate of aluminum is 30%.

[0083] Comparative Example 2

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

[0085] The detection shows that the leaching rate of scandium is 11%, the leaching rate of iron is 22%, the leaching rate of titanium is 9%, the leaching rate of calcium is 12%, the leaching rate of silicon is 25%, the leaching rate of magnesium is 21%, and the leaching rate of aluminum is 15%.

[0086] Comparative Example 3

[0087] Compared with Example 1, the difference is only that step (1) is not performed, and the Baiyunebo ore is directly subjected to step (2) and subsequent treatment, and other operations and parameters are the same as those in Example 1.

[0088] The detection shows that the leaching rate of scandium is 11%, the leaching rate of iron is 12%, the leaching rate of titanium is 5%, the leaching rate of calcium is 4%, the leaching rate of silicon is 3%, the leaching rate of magnesium is 7%, and the leaching rate of aluminum is 3%.

[0089] Comparative Example 4

[0090] Compared with Example 1, the difference is only that in step (2), component B is absent in the leaching solution, and the absent component B is supplemented by component A in equimolar amount, and other operations and parameters are the same as those in Example 1.

[0091] The detection shows that the leaching rate of scandium is 61%, the leaching rate of iron is 62%, the leaching rate of titanium is 51%, the leaching rate of calcium is 42%, the leaching rate of silicon is 35%, the leaching rate of magnesium is 41%, and the leaching rate of aluminum is 35%.

[0092] Comparative Example 5

[0093] The difference between the example 1 and the example 2 is that in the step (2), the ingredient A is absent in the leaching solution, and the absent ingredient A is supplemented by the ingredient B in equimolar amount, and other operations and parameters are the same as the example 1.

[0094] The detection shows that the leaching rate of scandium is 31%, the leaching rate of iron is 22%, the leaching rate of titanium is 21%, the leaching rate of calcium is 12%, the leaching rate of silicon is 5%, the leaching rate of magnesium is 11%, and the leaching rate of aluminum is 3%.

[0095] Comparative example 6

[0096] The difference between the example 1 and the example 2 is that in the step (2), the ingredient A is absent in the leaching solution, and the absent ingredient A is supplemented by the ingredient B in equimolar amount, and other operations and parameters are the same as the example 1.

[0097] The detection shows that the leaching rate of scandium is 31%, the leaching rate of iron is 22%, the leaching rate of titanium is 21%, the leaching rate of calcium is 12%, the leaching rate of silicon is 5%, the leaching rate of magnesium is 11%, and the leaching rate of aluminum is 3%.

[0098] The above examples are only used to describe the preferred embodiments of the present application, and are not used to limit the scope of the present application. Without departing from the design spirit of the present application, various modifications and improvements of the technical solutions of the present application made by the ordinary skilled in the art should fall into the protection scope of the present application defined by the claims.

Claims

1. A method for selective leaching of scandium from a scandium-containing mineral, characterized by, The scandium-containing mineral and the additive are subjected to roasting treatment to obtain a roasted material, and the roasted material and a leaching agent are mixed to obtain a scandium-rich leaching solution; the roasting atmosphere is an oxygen-containing atmosphere. The additive is an inorganic salt of at least one of sodium, calcium, potassium and ammonium. The leaching agent comprises a water solution of component A and component B; wherein the component A is a water-soluble di- and more carboxylic acid compound with 2~C 10 ; the component B is a water-soluble salt of component A. The molar ratio of component A to component B is 1:0.5-5, and the concentration of component A in the leaching agent is 1-15 mol / L. The Sc-containing mineral is a concentrate or tailings of a natural Sc-containing mineral, wherein Sc is embedded in the crystal lattice of at least one of a silicate and an oxide in the form of isomorphism, forming Sc 3+ a substitution-type intergrowth structure with non-Sc impurity elements.

2. The method for selectively leaching scandium from a scandium-containing mineral according to claim 1, characterized by, The scandium-containing mineral contains at least one of iron, titanium, silicon, aluminum, calcium, magnesium and rare earth elements as non-Sc impurities.

3. The method for selectively leaching scandium from a scandium-containing mineral according to claim 1, wherein The scandium-containing mineral includes at least one of scandium-containing bauxite, laterite nickel ore, titanium ore and Baiyunebo ore.

4. The method for selectively leaching scandium from a scandium-containing mineral according to claim 1, characterized by, The scandium-containing mineral contains niobium, rare earth, iron, scandium and titanium, wherein the content of TFe is 30±10%, the content of Ti is 15±5%, the content of Nb2O5 is 5±2%, the content of Si is 11±5%, the content of Ca is 5±2% and the content of Mg is 2±1%.

5. The method for selectively leaching scandium from a scandium-containing mineral according to claim 4, wherein The scandium-containing mineral contains at least one of scandium-containing bauxite, laterite nickel ore, titanium ore and Baiyunebo ore.

6. The method for selectively leaching scandium from a scandium-containing mineral according to claim 1, wherein The scandium-containing mineral contains niobium, rare earth, iron, scandium and titanium, wherein the content of TFe is 30±10%, the content of Ti is 15±5%, the content of Nb2O5 is 5±2%, the content of Si is 11±5%, the content of Ca is 5±2% and the content of Mg is 2±1%.

7. The method for selectively leaching scandium from a scandium-containing mineral according to claim 1, wherein The scandium content of the scandium-containing mineral is 100-1000 ppm.

8. The method for selectively leaching scandium from a scandium-containing mineral according to claim 7, wherein The additive includes at least one of a carbonate salt and a sulfate salt of the cation. The additive includes additive A and additive B, wherein additive A is an inorganic salt of at least one of sodium, potassium and ammonium, and additive B is an inorganic salt of calcium.

9. The method for selectively leaching scandium from a scandium-containing mineral as claimed in claim 1, 7 or 8, characterized by, The weight ratio of additive A to additive B is 1:0.5-2. The weight ratio of the scandium-containing mineral to the additive is 1:0.05-0.

5. The temperature of the roasting treatment process is 500-1000°C.

10. The method for selectively leaching scandium from a scandium-containing mineral according to claim 1, wherein The roasting treatment time is 0.5-5 h.

11. The method for selective leaching of scandium from a scandium-containing mineral according to claim 10, characterized in that, The leaching agent contains at least one of citric acid, oxalic acid, tartaric acid, malonic acid and ethylenediaminetetraacetic acid.

12. The method for selective leaching of scandium from a scandium-containing mineral according to claim 1, 10 or 11, characterized in that, Component B is at least one of a sodium salt, a potassium salt and an ammonium salt of component A.

13. The method for selective leaching of scandium from a scandium-containing mineral according to claim 1, characterized in that, The molar ratio of component A to component B is 1:0.7-1.

5.

14. The method for selectively leaching scandium from a scandium-containing mineral according to claim 1, wherein The liquid-solid ratio of the leaching process is 2-15 mL / g. The temperature of the leaching stage is 30-180°C. The leaching time is 0.5-12 h.

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