A leaching method for scandium-containing slag

Abstract

The present invention relates to the field of hydrometallurgy and specifically discloses a method for leaching scandium-containing slag. The method comprises wet-mechanically activating the scandium-containing slag in an aqueous solution containing an additive A to produce a slurry; the additive A is at least one of an alcoholic hydroxyl compound, acetone, and THF. The slurry is then mixed with an acidic substance and an oxidizing agent, subjected to a leaching treatment, and subsequently subjected to solid-liquid separation to produce a scandium-containing leachate and leached slag. The method can effectively improve the leaching rate of scandium and its associated valuable metals.

Description

Technical Field

[0001] The invention belongs to the technical field of nonferrous metal hydrometallurgy, and in particular relates to a leaching method for scandium-containing slag. Background Art

[0002] Industrial waste residues pose numerous environmental and safety challenges, and resource utilization technologies are a key solution. Due to differences in raw material types and sources, production methods, and treatment methods across various industrial sectors, the resulting waste residues contain a wide variety of components, resulting in a wide range of recycling methods.

[0003] Scandium has unique physical and chemical properties and is widely used in ceramics, alloys, and new materials. However, its low grade, unique properties, and frequent intercalation with other metals make its leaching and recovery extremely challenging. Using conventional agitation leaching techniques, scandium leaching rates typically range from 55% to 85%. While pressurization can enhance scandium leaching, the leaching rate is only close to 90%, leaving significant room for improvement. Furthermore, pressurized leaching significantly increases equipment and operating costs.

[0004] In addition, scandium is often embedded and coexists with valuable metals such as nickel and / or cobalt, which will further increase the difficulty of leaching each metal element and further affect the comprehensive recovery effect of scandium and other metals.

[0005] In summary, the industry urgently needs a method that can effectively leaching scandium and its accompanying metal elements under normal pressure. Summary of the Invention

[0006] In view of the problem that the atmospheric pressure leaching rate of scandium in scandium-containing solid materials is not ideal, the present invention aims to provide a leaching method for scandium-containing slag, aiming to improve the atmospheric pressure leaching rate of scandium and further simultaneously improve the leaching rate of valuable metals that may be associated therein.

[0007] A method for leaching scandium-containing slag comprises wet mechanical activation of the scandium-containing slag in an aqueous solution containing an additive A to prepare a slurry; the additive A is at least one of an alcoholic hydroxyl compound, acetone, and THF;

[0008] The slurry is then mixed with an acidic substance and an oxidant for leaching treatment, followed by solid-liquid separation to obtain a scandium-containing leachate and leach residue.

[0009] In response to the problem of unsatisfactory atmospheric pressure leaching rate of scandium in scandium-containing slag, the present invention innovatively studies that mechanical activation of the scandium-containing slag with the assistance of additive A in advance, and further combining it with a subsequent oxidant-assisted acid leaching treatment process, can achieve synergy and synergistically improve the atmospheric pressure leaching effect of scandium.

[0010] In the present invention, the scandium-containing slag material can be any solid material containing scandium, for example, it can be at least one of waste materials and minerals containing scandium.

[0011] In the present invention, there is no particular requirement for the occurrence phase of scandium in the scandium-containing slag. For example, the scandium may be in the form of at least one of a simple substance, an oxide, and a sulfate.

[0012] In the present invention, there is no special requirement for the scandium content of the scandium-containing slag. Considering the economic value of the treatment, the scandium content in the scandium-containing slag is above 0.05 wt.%.

[0013] In the present invention, the scandium-containing slag can be a solid material accompanying scandium and other valuable metal elements. For example, the scandium-containing slag can also contain at least one of nickel and cobalt. For example, the scandium-containing slag can be at least one of scandium-nickel slag, scandium-cobalt slag, or scandium-nickel-cobalt slag. The present invention utilizes the innovative leaching method to achieve efficient leaching of scandium while simultaneously and effectively leaching other accompanying metal components, such as nickel and / or cobalt.

[0014] In the present invention, when the scandium-containing slag material further contains other valuable metals, the content of the other valuable metals may be above 0.05 wt. % in consideration of processing efficiency and economic value.

[0015] In the present invention, the scandium-containing slag is innovatively mechanically activated with the aid of additive A, which is beneficial for synergistically coordinating with the subsequent leaching process and synergistically improving the atmospheric pressure leaching rate of scandium. When other valuable metals are also contained therein, it is also beneficial for improving the synchronous leaching rate of other valuable metals.

[0016] In the present invention, in the auxiliary agent A, the alcoholic hydroxyl group-containing compound is a compound having 1 to 10 carbon atoms and containing one or more alcoholic hydroxyl groups, preferably at least one of triethanolamine, ethylene glycol, and acetone.

[0017] Preferably, the auxiliary agent A is at least one of triethanolamine, ethylene glycol, and acetone.

[0018] Preferably, the additive A accounts for more than 0.05 wt% of the scandium-containing slag, preferably more than 0.1 wt%. More preferably, it accounts for 0.1 to 0.5 wt%.

[0019] In the present invention, the wet mechanical activation can be wet ball milling. Preferably, the obtained slurry is controlled to have a content of particles with a diameter of less than 0.074 mm accounting for more than 50%, and a solid content of the slurry is 20-60 wt%, and can further be 35-45 wt%.

[0020] In the present invention, an acidic substance and an oxidant are added to the obtained slurry, and the accompanying leaching effect of scandium and other valuable metals is synergistically improved by means of joint control of the components.

[0021] In the present invention, the oxidant may be any oxidizing component having oxidizing ability, for example, it may be at least one of hypochlorous acid and its salts, hydrogen peroxide, and persulfide;

[0022] The amount of the oxidant can be adjusted as needed. For example, the oxidant is 0.1 to 20 wt % of the scandium-containing slag. Considering the processing cost, the amount of the oxidant can be reasonably controlled according to the type of oxidant. For example, when the oxidant is calcium hypochlorite, the mass of calcium hypochlorite is 0.3 to 3% of the mass of the scandium-containing slag. When the oxidant is hydrogen peroxide, the mass of hydrogen peroxide is 1 to 15% of the mass of the scandium-containing slag.

[0023] In the present invention, the acidic substance may be a water-soluble acidic component known in the industry, for example, an inorganic and / or organic acid, more preferably at least one of sulfuric acid and hydrochloric acid.

[0024] In the present invention, the pH of the initial leaching solution is 0.5-3.

[0025] In the present invention, the leaching stage is carried out under normal pressure;

[0026] Preferably, the temperature in the leaching stage is lower than 100°C, preferably 15 to 95°C, and can be further 70 to 85°C considering the processing efficiency;

[0027] In the present invention, the leaching time can be controlled based on existing means. For example, the leaching rate can be monitored based on conventional means according to the treatment temperature, thereby controlling the leaching time. For example, when the temperature is high, the leaching time can be appropriately shortened, and when the temperature is low, the leaching time can be appropriately extended. In the present invention, the leaching time is more than 0.5 hours, and can be further extended to 1 to 8 hours in consideration of the treatment efficiency.

[0028] In another embodiment of the present invention, the scandium-containing slag may be replaced with a slag containing nickel and / or cobalt, thereby achieving efficient leaching of nickel and / or cobalt at normal pressure.

[0029] Beneficial effects

[0030] In the present invention, based on the control of the process, the atmospheric pressure leaching rate of scandium can be effectively improved.

[0031] Moreover, for composite difficult-to-treat solid waste containing scandium, nickel and cobalt, the method of the present invention can still achieve excellent scandium leaching effect, and can also improve the synchronous leaching rate of embedded associated metals such as nickel and cobalt. Studies have found that the atmospheric pressure leaching rate of scandium can reach 97%, the atmospheric pressure leaching rate of cobalt can reach 90%, and the atmospheric pressure leaching rate of nickel can reach 97%, with excellent preparation effect.

[0032] In the present invention, the mass of the leached residue is reduced by more than 65% compared with the original waste residue. After dehydration, the leached residue can be used as a raw material for ceramic building materials for sale, so that resources are fully utilized and significant economic and environmental benefits are achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is the XRD pattern of the slag after leaching in Example 1; DETAILED DESCRIPTION

[0034] The following examples are intended to illustrate the present invention rather than to further limit the present invention.

[0035] A specific embodiment of the present invention is directed to the difficult-to-treat scandium-cobalt-nickel waste residue, and the leaching steps are as follows:

[0036] Step 1: Add additive A for grinding

[0037] The waste residue is crushed, slurried with water, and ball-milled with additive A to control the content of waste residue with a particle size of less than 0.074 mm to be more than 50%, and the slurry concentration to be about 40%;

[0038] Step 2: Add acid and oxidant for acid leaching

[0039] Acid and an oxidant are added to the waste slag slurry obtained in the first step and stirred. The liquid-solid ratio of acid to waste slag is (2-5):1. The leaching temperature is room temperature to 90°C, the leaching time is 1-8 hours, and the stirring speed is 100-150 rpm. The solid-liquid separation obtains an acid leaching solution and a leaching residue. The leaching solution enters the next process for recovery of scandium, cobalt, and nickel elements. The leaching residue can be used as a raw material for ceramic building materials after dehydration and sold.

[0040] In the first step of the present invention, the auxiliary agent A is at least one of triethanolamine, acetone, and ethylene glycol, wherein the amount of triethanolamine is 0.1-0.4% of the mass of the waste residue, the amount of acetone is 0.1-0.3% of the mass of the waste residue, and the amount of ethylene glycol is 0.1-0.3% of the mass of the waste residue.

[0041] In the first step of the present invention, the content of the ore pulp with a particle size of 0.074 mm after ball milling accounts for more than 50%, and the ore pulp concentration is about 40%.

[0042] In the second step of the present invention, the acid is a sulfuric acid solution, wherein the sulfuric acid concentration is 25-60%, and the mass of the sulfuric acid is 5-40% of the mass of the waste residue.

[0043] In the second step of the present invention, the oxidant is at least one of calcium hypochlorite and hydrogen peroxide, wherein the mass of calcium hypochlorite is 0.3-3% of the mass of the waste residue, and the mass of hydrogen peroxide is 1-15% of the mass of the waste residue.

[0044] In the following cases of the present invention, the contents of scandium, cobalt and nickel in the slag are all expressed in percentage by weight.

[0045] The percentage of additive A and oxidant added is relative to the dry weight of slag.

[0046] Unless otherwise stated, the leaching stage was carried out at normal pressure.

[0047] Unless otherwise stated, the hydrogen peroxide used was 30 wt % hydrogen peroxide.

[0048] Example 1:

[0049] This example uses Hubei scandium-cobalt-nickel waste slag (the main phases of the waste slag are quartz, gypsum, and wutrite, i.e., SiO2, calcium sulfate, ferrous oxide, etc., with scandium and other elements embedded therein), and the contents of scandium, cobalt, and nickel in the waste slag are 0.11%, 0.16%, and 0.71%, respectively. The specific steps are as follows:

[0050] ① Weigh 100g of scandium-cobalt-nickel waste slag and 100ml of water, and mix them to obtain a mixed slurry with a slurry concentration of 50%;

[0051] ② After adding 0.2g of auxiliary agent A triethanolamine to the mixed slurry, the mixture was sent to a ball mill for 7 minutes (XMQΦ240×90 conical ball mill, cylinder speed 90r / min, feed particle size <3mm, discharge particle size 0.074mm), and the grinding fineness was -0.074mm, accounting for 88%;

[0052] ③ Pour the finely ground waste slag slurry into a three-necked round-bottom flask, add 20 ml of 60% sulfuric acid and 2 g of calcium hypochlorite as an oxidant, add water to adjust the liquid-solid ratio of acid to waste slag to 5:1 (control the pH of the leaching starting solution to 0.5), control the leaching temperature to 80°C, the leaching time to 6 hours, and the stirring speed to 150 rpm;

[0053] ④ After the leaching reaction is completed, the solid and liquid are separated to obtain acid leaching solution and leaching residue. The leaching solution enters the next process to recover the scandium, cobalt and nickel elements. The leaching residue can be used as a raw material for ceramic building materials after dehydration and sold.

[0054] At this time, the leaching rates of scandium, cobalt and nickel were 97.35%, 90.09% and 97.04%, respectively.

[0055] Example 2:

[0056] Compared with Example 1, the only difference is that, in ②, an equal weight of acetone is used to replace the triethanolamine, and the other operations and parameters are the same as those in Example 1.

[0057] At this time, the leaching rates of scandium, cobalt and nickel were 96.95%, 89.22% and 97.10%, respectively.

[0058] Example 3:

[0059] Compared with Example 1, the only difference is that, in ②, an equal weight of ethylene glycol is used to replace the triethanolamine, and the other operations and parameters are the same as those in Example 1.

[0060] At this time, the leaching rates of scandium, cobalt and nickel were 95.13%, 88.18% and 96.21%, respectively.

[0061] Example 4:

[0062] Compared with Example 1, the only difference is that, in ③, 40% sulfuric acid is used instead of 60% sulfuric acid and the pH of the leaching starting solution is controlled to 1.5. Other operations and parameters are the same as in Example 1.

[0063] At this time, the leaching rates of scandium, cobalt and nickel were 95.84%, 89.89% and 95.94%, respectively.

[0064] Example 5:

[0065] Compared with Example 1, the only difference is that, in ③, the liquid-solid ratio is adjusted so that the pH of the leaching starting solution is 2.5. Other operations and parameters are the same as in Example 1.

[0066] At this time, the leaching rates of scandium, cobalt and nickel were 96.25%, 90.02% and 97.11%, respectively.

[0067] Example 6:

[0068] Compared with Example 1, the only difference is that in ③, the leaching temperature is controlled to 40°C, and other operations and parameters are the same as Example 1.

[0069] At this time, the leaching rates of scandium, cobalt and nickel were 95.98%, 85.33% and 92.29%, respectively.

[0070] Example 7:

[0071] Compared with Example 1, the only difference is that in ③, the leaching time is controlled to 2 hours, and the other operations and parameters are the same as Example 1.

[0072] At this time, the leaching rates of scandium, cobalt and nickel were 94.34%, 84.54% and 94.33%, respectively.

[0073] Example 8:

[0074] Compared with Example 1, the only difference is that, in ②, 10g of hydrogen peroxide is used to replace the 2g of calcium hypochlorite, and other operations and parameters are the same as in Example 1.

[0075] At this time, the leaching rates of scandium, cobalt and nickel were 97.54%, 90.10% and 97.31%, respectively.

[0076] Comparative Example 1

[0077] Compared with Example 1, the only difference is that, in ②, triethanolamine is not added, and other operations and parameters are the same as in Example 1.

[0078] At this time, the leaching rates of scandium, cobalt and nickel were 81.23%, 66.91% and 86.52% respectively.

[0079] Comparative Example 2

[0080] Compared with Example 1, the only difference is that, in ②, an equal weight of carbonic acid amide is used to replace the triethanolamine, and other operations and parameters are the same as those in Example 1.

[0081] At this time, the leaching rates of scandium, cobalt and nickel were 80.14%, 68.95% and 88.90%, respectively.

[0082] Comparative Example 3

[0083] Compared with Example 1, the only difference is that in ③, calcium hypochlorite is not added, and other operations and parameters are the same as in Example 1.

[0084] At this time, the leaching rates of scandium, cobalt and nickel were 78.17%, 67.66% and 89.30% respectively.

[0085] Comparative Example 4

[0086] Compared with Example 1, the only difference is that in ②, no triethanolamine is added, and in ③, no calcium hypochlorite is added. Other operations and parameters are the same as in Example 1.

[0087] At this time, the leaching rates of scandium, cobalt and nickel were 73.25%, 60.62% and 88.01% respectively.

Claims

1. A method for leaching scandium-containing slag, characterized in that: The scandium-containing slag is wet-mechanically activated in an aqueous solution containing an additive A to prepare a slurry; the additive A is at least one of triethanolamine, ethylene glycol, and acetone; and the additive A is at least 0.05 wt% of the scandium-containing slag; The slurry is then mixed with an acidic substance and an oxidant for leaching treatment, followed by solid-liquid separation to obtain a scandium-containing leachate and leach residue.

2. The method for leaching scandium-containing slag according to claim 1, wherein: The scandium-containing slag is at least one of waste materials and minerals containing scandium.

3. The method for leaching scandium-containing slag according to claim 2, wherein: In the scandium-containing slag, the scandium exists in at least one phase form of a simple substance, an oxide, or a sulfate.

4. The method for leaching scandium-containing slag according to claim 2, wherein: The scandium content in the scandium slag is above 0.05 wt.%.

5. The method for leaching scandium-containing slag according to claim 2, wherein: The scandium-containing slag is also allowed to contain at least one of nickel and cobalt.

6. The method for leaching scandium-containing slag according to claim 5, wherein: The scandium-containing slag is at least one of scandium-nickel slag, scandium-cobalt slag, and scandium-nickel-cobalt slag.

7. The method for leaching scandium-containing slag according to claim 1, wherein: The additive A is greater than 0.1 wt.% of the scandium-containing slag.

8. The method for leaching scandium-containing slag according to claim 7, wherein: The additive A is 0.1-0.5 wt.% of the scandium-containing slag.

9. The method for leaching scandium-containing slag according to claim 1, wherein: The wet mechanical activation is wet ball milling.

10. The method for leaching scandium-containing slag according to claim 1, wherein: The obtained slurry is controlled so that the content of particles with a diameter less than 0.074 mm accounts for more than 50%, and the solid content of the slurry is 20-60wt%.

11. The method for leaching scandium-containing slag according to claim 1, wherein: The oxidant is at least one of hypochlorous acid and its salts, hydrogen peroxide, and persulfide.

12. The method for leaching scandium-containing slag according to claim 11, wherein: The oxidant is 0.1-20 wt% of scandium-containing slag.

13. The method for leaching scandium-containing slag according to claim 1, wherein: The acidic substance is a water-soluble acidic substance.

14. The method for leaching scandium-containing slag according to claim 13, wherein: The acidic substance is at least one of sulfuric acid and hydrochloric acid.

15. The method for leaching scandium-containing slag according to claim 1, wherein: The pH of the initial leaching solution is 0.5~3.

16. The method for leaching scandium-containing slag according to claim 1, wherein: The leaching stage is carried out at atmospheric pressure.

17. The method for leaching scandium-containing slag according to claim 1, wherein: The temperature during the leaching stage is below 100°C.

18. The method for leaching scandium-containing slag according to claim 17, wherein: The temperature in the leaching stage is 15~95℃.

19. The method for leaching scandium-containing slag according to claim 1, wherein: The leaching time is more than 0.5h.

20. The method for leaching scandium-containing slag according to claim 1, wherein: The leaching time is 1~8h.

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