NICKEL STRIPPING COMPOSITION AND APPLICATION THEREOF

Abstract

 The present disclosure provides a novel nickel stripping composition, which comprises 10 to 40 wt% sodium sulfite; 10 to 40 wt% sodium bisulfate; 10 to 40 wt% sodium thiosulfate; and 10 to 40 wt% trisodium citrate. The weight percentages described above are based on a total weight of the nickel stripping composition. The present disclosure also provides a nickel stripping solution comprising the nickel stripping composition and a recycling method of nickel metal using the nickel stripping solution.

Description

BACKGROUND OF THE INVENTION

FIELD OF THE INVENTION

[0001] The present disclosure relates to a composition for stripping metal and, in particular, to a composition for stripping nickel and application thereof.

DESCRIPTION OF THE PRIOR ART

[0002] Along with the innovation of various electronic products, the usage of batteries also increases, and its technology is also changing with each passing day. The speed of replacement electronic products is very fast, and a large amount of e-waste is generated as a result. Lithium-ion polymer batteries commonly used in electronic products currently use a variety of metal composite materials as the positive electrodes, and most of them are high-nickel materials, such as high-nickel ternary materials. Since the mineral resources on the earth are not inexhaustible, under the consideration of sustainable development, how to recycle the metal components from electronic waste, such as waste batteries, has gradually become one of the most important work links in the industry.

[0003] Currently known methods for recycling/recovering nickel metal from battery waste include electric furnace smelting or treating with concentrated ammonia or sulfuric acid. The three recycling/recovery methods have many disadvantages to the environment, safety, health, etc. Electric furnace smelting (fire method) requires high temperatures above 1,000-2,000°C, and produces a large amount of toxic and harmful waste gas and carbon dioxide emissions, which is a heavy industry with high energy consumption and high pollution. Concentrated ammonia water (ammonia immersion method) is volatile and produces a large amount of pungent odor. The equipment for ammonia immersion has high requirements for sealing and corrosion resistance, and also produces a large amount of difficult-to-treat wastewater, of which the recycling rate is only 70-80%. Concentrated sulfuric acid method (acid immersion method) has low efficiency and usually requires extremely high temperature and pressure. The use of other strong oxidants in acid immersion makes the operating environment harsh and will erosion organic matter, such as plastics. Highly toxic hydrogen sulfide gas is easily produced to cause chemical oxygen demand (COD) of wastewater rise. Using these methods to obtain nickel metal often sacrifices environmental sustainability or the health and safety of operators, and does not meet the 12th item "Responsible Consumption and Production" among the 17 Sustainable Development Goals (SDGs) of the United Nations, which is not ideal in terms of safety and environmental protection.

[0004] In summary, there is a need for a safe, efficient and widely used recycling /recovery method in the field of metal recycling/recovery. In view of this, the present disclosure attempts to provide an environmentally friendly nickel stripping technology to recycle/recover nickel metal resources more efficiently.

SUMMARY OF THE INVENTION

[0005] The present invention provides a novel nickel stripping composition, a nickel stripping solution comprising the composition and a method for recycling nickel metal using the stripping solution. Compared with the conventional method, the recycling efficiency of the nickel metal of the article treated by the composition is greatly improved, and the reaction can be carried out at normal temperature or normal pressure, so the harm to the operator and the natural environment is relatively low.

[0006] According to one embodiment of the present invention, a nickel stripping composition is provided. The nickel stripping composition comprises 10 to 40 wt% sodium sulfite, 10 to 40 wt% sodium bisulfate, 10 to 40 wt% sodium thiosulfate and 10 to 40 wt% trisodium citrate, wherein the weight percentages are based on a total weight of the nickel stripping composition.

[0007] In one embodiment, the nickel stripping composition comprises 25 to 40 wt% sodium sulfite, 10 to 25 wt% sodium bisulfate, 25 to 40 wt% sodium thiosulfate and 10 to 25 wt% trisodium citrate.

[0008] According to another embodiment of the present invention, a nickel stripping solution is provided. The nickel stripping solution comprises 10 to 50 grams of the nickel stripping composition described above, 300 to 800 ml of sulfuric acid and a solvent per liter.

[0009] In one embodiment, the solvent is water.

[0010] In one embodiment, the sulfuric acid is 50% sulfuric acid.

[0011] According to a further embodiment of the present invention, a recycling method of nickel metal is provided. The recycling method comprises the following steps: (A) providing an article to be treated; (B) soaking the article to be treated in the nickel stripping solution described above to proceed with a reaction between the article and the nickel stripping solution; (C) filtering a product of the step (B) to obtain an eluate; and (D) performing a reduction reaction on the eluate to obtain nickel metal.

[0012] In one embodiment, the article to be treated in the step (A) includes nickel-containing powder and an object having a nickel-plated surface.

[0013] In one embodiment, a weight ratio (solid-to-liquid ratio) of the article to be treated to the nickel stripping solution in the step (B) is between 1:1 and 1:15.

[0014] In one embodiment, the nickel-containing powder includes crushed batteries, nickel ore, slag and high-entropy alloys.

[0015] In one embodiment, when the article to be treated is the object having the nickel-plated surface, a reaction temperature of the step (B) is maintained at 20 to 40°C, and a weight ratio of the article to be treated to the nickel stripping solution is between 1:1 and 1:5.

[0016] In one embodiment, when the article to be treated is the nickel-containing powder, a reaction temperature of the step (B) is maintained at 60 to 90°C, and a weight ratio of the article to be treated to the nickel stripping solution is between 1:5 and 1:15.

[0017] In order to make the above-mentioned objects, features, advantages and other aspects of the present invention clearer, specific examples are given below, and the technical content of the present invention is described in more detail in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] 

FIG. 1 shows a flow chart of a recycling method for nickel metal according to an embodiment of the present invention.

FIG. 2 shows photos of the nickel-plated copper heat spreader, wherein FIG. 2A shows the nickel-plated copper heat spreader before the treatment of the nickel stripping solution of the present invention, and FIG. 2B shows the nickel-plated copper heat spreader after the treatment of the nickel stripping solution of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0019] Nickel is a metal commonly used in batteries in current various electronic products and electric vehicles. Its development is changing with each passing day, and the speed of replacing the old with the new is very fast, which also produces a large amount of battery waste. Using the nickel stripping composition of the present invention to treat battery waste can strip nickel metal from the waste more effectively and improve recycling efficiency.

[0020] The nickel stripping composition of the present invention comprises several specific salts mixed in specific proportions. Preferably, the nickel stripping composition comprises 10 to 40 wt% sodium sulfite (Na₂SO₃), 10 to 40 wt% sodium bisulfate (NaHSO₄), 10 to 40 wt% sodium thiosulfate (Na₂S₂O₃) and 10 to 40 wt% trisodium citrate (Na₃C₆H₅O₇). The weight percentages are based on the total weight of the nickel stripping composition.

[0021] In an exemplary embodiment, the nickel stripping composition comprises 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39 or 40 wt% sodium sulfite. In another exemplary embodiment, the nickel stripping composition comprises 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39 or 40 wt% sodium bisulfate. In yet another exemplary embodiment, the nickel stripping composition comprises 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39 or 40 wt% sodium thiosulfate. In yet another exemplary embodiment, the nickel stripping composition comprises 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39 or 40 wt% trisodium citrate. In a feasible embodiment, sodium sulfite, sodium bisulfate, sodium thiosulfate and trisodium citrate are combined in a weight percentage selected from the exemplary embodiments disclosed above.

[0022] In a preferable embodiment of the present invention, the nickel stripping composition comprises 25 to 40 wt% sodium sulfite (Na₂SO₃), 10 to 25 wt% sodium bisulfate (NaHSO₄), 25 to 40 wt% sodium thiosulfate (Na₂S₂O₃) and 10 to 25 wt% trisodium citrate (Na₃C₆H₅O₇).

[0023] The nickel stripping composition of the present invention contains specific proportions of sodium salts, such as sodium sulfite, sodium bisulfate, sodium thiosulfate and trisodium citrate. The inventors unexpectedly found that the composition prepared under the combination of the above components and their relative weight ratios can be combined with sulfuric acid to produce an excellent nickel metal stripping effect.

[0024] As mentioned above, the nickel stripping composition of the present invention can be used with sulfuric acid to make a nickel stripping solution. The nickel stripping solution contains 10 to 50 grams of the above-mentioned nickel stripping composition, 300 to 800 milliliters (ml) of sulfuric acid, and a solvent per 1 liter.

[0025] In an exemplary embodiment, the nickel stripping solution contains 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, or 50 grams of nickel stripping composition. In another exemplary embodiment, the nickel stripping solution contains 300, 350, 400, 450, 500, 550, 600, 650, 700, 750 or 800 ml of sulfuric acid.

[0026] The above-mentioned solvent is preferably water, and the sulfuric acid can be 25% or 50% (v/v) sulfuric acid.

[0027] The present invention further provides a method for recovering nickel metal using the nickel stripping solution described above. The step and process can refer to FIG. 1: (A) first, providing an article to be treated; then, (B) soaking the article to be treated in the nickel stripping solution; (C) filtering to obtain a filtrate (eluate) and residue; and (D) performing a reduction reaction on the eluate to obtain nickel metal.

[0028] The article to be treated of the present invention includes the object having the nickel-plated surface and the nickel-containing powder. The object having the nickel-plated surface is, for example, a nickel-plated copper sheet. The nickel-containing powder is obtained by pulverizing nickel-containing articles, such as waste batteries, nickel ore, slag, high-entropy alloys, and the like. Waste batteries are, for example, lithium-ion polymer batteries, whose anode materials include but are not limited to high-nickel ternary polymers such as nickel-cobalt lithium manganese or nickel-cobalt lithium aluminate, in which the main component is the nickel to be recovered in the present invention. After screening these ternary waste batteries, they can be destroyed by known physical methods (such as crushing, pulverizing, etc.) to obtain lithium-ion waste battery powder.

[0029] The soaking step (B) shown in FIG. 1 is achieved by placing the article to be treated in step (A) in a bath comprising the aforementioned nickel stripping solution. The article to be treated is preferably immersed in the nickel stripping solution for a predetermined time, so that the article to be treated reacts with the stripping solution. The predetermined time varies according to the amount of the article to be treated, the reaction conditions and its actual needs, and generally ranges from a few seconds to 8 hours. The operator can adjust freely.

[0030] The nickel in the article to be treated will remain in the solution in the form of ions during the soaking process, and can be recovered in the subsequent reduction reaction. The soaking process is an exothermic reaction, so it can be carried out directly at atmospheric pressure and room temperature without additional pressure and heating. Alternatively, the temperature can be controlled between 20°C and 90°C, and the formulation of the present invention can maintain a certain reaction rate under this temperature.

[0031] In step (B), the ratio (solid-to-liquid ratio) of the article to be treated to the stripping liquid is preferably 1:1 to 1:15. In a possible embodiment, the stripping solution completely submerged the article to be treated. In addition, vibration, stirring, etc. can be used to shake the object to be treated in the aforementioned bath to facilitate the reaction, and the rotation speed is preferably between 0 and 500 rpm. Suggested operating parameter ranges for step (B) are listed in Table 1 below:

Table 1 step (B) operating range

	Operating range (1)	Operating range (2)
Temperature (°C)	20-40	60-90
Time	seconds - 1 hour	2-8 hours
solid-to-liquid ratio (g:mL)	(1:1) - (1:5)	(1:5) - (1:15)
Rotation speed (rpm)	0-300	300-500
Nickel stripping composition content* (g/L)	30-50g	10-30g
50% sulfuric acid content** (mL/L)	300-500	500-800

*The content of nickel stripping composition refers to the amount of nickel stripping composition contained in 1L nickel stripping solution. **50% sulfuric acid content refers to the amount of 50% sulfuric acid used in 1L nickel stripping solution.

[0032] The operation range (1) in table 1 is suitable for the recycling of nickel on objects having nickel-plated surfaces. The operation range (2) is suitable for the recycling of nickel in nickel-containing powder, and the powder size is preferably able to pass through the sieve with 20 mesh or above (particle size <0.85mm), such as lithium battery powder (black powder), ore sand, slag, etc.

[0033] The step (C) shown in FIG. 1 obtains a solid residue and a liquid eluate by filtering the soaked product of the step (B). The filtering method is, for example, suction filtration, but other filtering methods can also be used, and the present invention is not limited thereto.

[0034] As mentioned above, the nickel in the article to be treated will remain in the liquid eluate in the form of ions after reacting with the stripping solution. In step (D) shown in FIG. 1, nickel can be recovered through reduction reaction. The reduction reaction can be known to those skilled in the art (such as electrolysis).

Example 1 Preparation of nickel stripping composition and nickel stripping solution

[0035] According to the composition ratio shown in the following table 2, 4 kinds of stripping nickel compositions having formulations A-D respectively are prepared. The preparation method of the nickel stripping composition includes weighing the salts with correct proportions and mixing them directly.

[0036] The nickel stripping composition of the present invention can be mixed with 50% sulfuric acid to prepare the nickel stripping solution. The preparation method of the stripping solution includes preparing a volumetric flask with a capacity of 1 liter and adding 10-50 grams of nickel stripping composition and 300-800 ml of 50% sulfuric acid. After the composition is completely dissolved, water is added to 1 liter scale to complete the nickel stripping solution. In the following examples, the nickel stripping solutions were formulated with the nickel stripping compositions having formulations A-D respectively of the present invention. The nickel stripping solution of Comparative Example 1 did not contain the nickel stripping composition at all, and directly used 25% sulfuric acid for soaking. In Comparative Example 2, no nickel stripping composition was added at all, and 50% sulfuric acid was directly used as the stripping solution for soaking.

Example 2 Recycling efficiency test of nickel stripping solution

[0037] The present embodiment used the nickel stripping compositions of formulations A-D in Table 2, added 50% sulfuric acid to formulate into nickel stripping solutions, carried out nickel stripping tests of 3 kinds of different nickel-containing powders (battery powder, nickel ore, slag), and compared with the comparative examples that directly used 25% and 50% sulfuric acid as the stripping solution. The experimental parameters are the operating range (2) in Table 1, and the experimental results are listed in Table 3. The experimental steps are as follows:

[0038] High-nickel battery powder: 10g of nickel stripping compositions of each of formulations A-D, 800ml of 50% sulfuric acid and water were mixed to formulate into 1L nickel stripping solution. Adding 100.00 grams of battery powder in the 1L nickel stripping solution (having a solid-to-liquid ratio of 1:10), then a stirrer were added to react the mixture at a speed of 300 rpm for 8 hours, and the reaction temperature was maintained at 90°C by a constant temperature bath. Finally, the product was filtered by suction, and the eluate was retained.

[0039] The battery powder contains relatively high concentration of nickel (10,000-30,000 ppm) and a variety of other metals (lithium, cobalt, iron, aluminum, copper, etc.). It is necessary to increase the amount of sulfuric acid in the stripping solution, the reaction temperature and the reaction time (8 hours) to ensure sufficient reaction.

[0040] Nickel ore powder: After 20g of nickel stripping composition, 600ml of 50% sulfuric acid and water were formulated into 1L nickel stripping solution, 66.7 grams of nickel ore powder (having a solid-to-liquid ratio of 1:15) and a stirrer were added to react at a speed of 400 rpm for 4 hours, and the reaction temperature was maintained at 70°C by a constant temperature bath. Finally, the product was filtered by suction, and the eluate was retained.

[0041] Because the iron ore powder contained various minerals, and the particle sizes of these minerals are different, more stripping solution (solid-to-liquid ratio up to 1:15) was needed and the stirring speed was increased to ensure that the powder and the immersion solution are fully reacted. However, because the nickel content in the iron ore sand powder was relatively low (about 1,000-5,000 ppm), the reaction time was only 4 hours.

[0042] Slag: After 25g of nickel stripping composition, 500ml of 50% sulfuric acid and water were formulated into 1L nickel stripping solution, 200 grams of slag (having a solid-to-liquid ratio of 1:5) and a stirrer were added to react at a speed of 500 rpm for 6 hours, and the reaction temperature was maintained at 50°C by a constant temperature bath. Finally, the product was filtered by suction, and the eluate was retained.

[0043] The slag powder was the waste from the production process of the steelmaking plant. In addition to nickel (about 500-2,000 ppm), it also contained a large amount of iron, chromium, aluminum and other metals. Therefore, the reaction temperature was lowered to 50°C and the use amount of the stripping solution (solid-to-liquid ratio of only 1:5) was reduced, which could effectively recover nickel and avoid the reactions between the stripping solution and other metals.

[0044] The concentration of nickel in the eluate can be measured to calculate the exact weight. In addition, the filtered residue is treated with aqua regia nitrification method to calculate the exact weight of the remaining (not stripped) nickel. The sum of these two items is the total amount of nickel in the original powder (battery, nickel ore, slag). Therefore, the calculation formula of the recycling rate is as follows:

[0045] Table 3 above is the recycling rate test results of the nickel stripping solutions. Comparing the recycling rates of the nickel stripping composition formulations A-D of the present invention and Comparative Examples 1 and 2 (without using the nickel stripping composition), it can be known that the nickel stripping composition/nickel stripping solution of the present invention can significantly improve the stripping efficiency of nickel in processing nickel-containing powder, such as battery, nickel ore, slag, etc., thereby greatly improving the final recycling rate.

[0046] In fact, in addition to improving the stripping efficiency of nickel, the nickel stripping composition of the present invention can further improve the selectivity of sulfuric acid to nickel metal, with reference to the following Example 3.

Example 3 Selective stripping effect of stripping solution

[0047] In this embodiment, the stripping compositions in Table 2 were used to treat common nickel-plated copper heat spreaders in semiconductor components (Fig. 2A). The surface of the nickel-plated copper heat spreader was nickel metal, and the weight ratio of nickel and copper was about 3%: 97%. According to the formulation in Table 1, this embodiment used 35g of nickel stripping composition, 300ml of 50% sulfuric acid and water to prepare 1L of nickel stripping solution, then the nickel-plated copper heat spreader (100g, solid-to-liquid ratio about 1:3) was soaked in a small amount of stripping solution (200ml) to react at room temperature for 30 minutes for peeling. The stirrer was operated at low speed (100 rpm) to create slight turbulence during stripping. Finally, the concentrations of nickel and copper ions in the eluate were measured and compared with Comparative Examples 1 and 2 that were not added with the nickel stripping composition. The results are shown in Table 4.

[0048] According to the above table, it can be seen that the nickel stripping solution of the present invention can effectively recover the nickel-plated on the heat spreader, and hardly damage the copper substrate with only a micro-etching effect. In contrast, 25% sulfuric acid and 50% sulfuric acid of Comparative Examples not only poor at nickel stripping, but also strip copper substrate at the same time. Therefore, the nickel stripping composition and the nickel stripping solution of the present invention can effectively recover nickel metal, have high selectivity for nickel, and improve the overall recycling performance.

[0049] Although the present invention has been described above with embodiments, it should be understood that the listed embodiments are only illustrative examples of the claimed invention, rather than limitations of the present invention. The protection scope of the present invention should be based on the appended claims.

Claims

1. A nickel stripping composition, comprising:

10 to 40 wt% sodium sulfite;

10 to 40 wt% sodium bisulfate;

10 to 40 wt% sodium thiosulfate; and

10 to 40 wt% trisodium citrate,

wherein the weight percentages are based on a total weight of the nickel stripping composition.

2. The nickel stripping composition of claim 1, comprising:

25 to 40 wt% sodium sulfite;

10 to 25 wt% sodium bisulfate;

25 to 40 wt% sodium thiosulfate; and

10 to 25 wt% trisodium citrate.

3. A nickel stripping solution, comprising:

10 to 50 grams of the nickel stripping composition of claim 1 or 2;

300 to 800 ml of sulfuric acid; and

a solvent per liter.

4. The nickel stripping solution of claim 3, wherein the solvent is water.

5. The nickel stripping solution of claim 3, wherein the sulfuric acid is 50% sulfuric acid.

6. A recycling method of nickel metal, comprising:

(A) providing an article to be treated;

(B) soaking the article to be treated in the nickel stripping solution of any one of claims 3 to 5 to proceed with a reaction between the article and the nickel stripping solution;

(C) filtering a product of the step (B) to obtain an eluate; and

(D) performing a reduction reaction on the eluate to obtain nickel metal.

7. The recycling method of claim 6, wherein the article to be treated in the step (A) includes nickel-containing powder and an object having a nickel-plated surface.

8. The recycling method of claim 6, wherein a weight ratio of the article to be treated to the nickel stripping solution in the step (B) is between 1:1 and 1:15.

9. The recycling method of claim 7, wherein the nickel-containing powder includes crushed batteries, nickel ore, slag and high-entropy alloys.

10. The recycling method of claim 7, wherein when the article to be treated is the object having the nickel-plated surface, a reaction temperature of the step (B) is maintained at 20 to 40°C, and a weight ratio of the article to be treated to the nickel stripping solution is between 1:1 and 1:5.

11. The recycling method of claim 7, wherein when the article to be treated is the nickel-containing powder, a reaction temperature of the step (B) is maintained at 60 to 90°C, and a weight ratio of the article to be treated to the nickel stripping solution is between 1:5 and 1:15.

Drawing