A method for recovering nickel

Abstract

The present application relates to a kind of nickel recovery method, its steps include: providing nickel aqueous solution, and the nickel aqueous solution contains nickel ion and impurity ion;The nickel aqueous solution is adjusted to first pH value, and first nickel precipitation filter cake and first nickel precipitation filtrate are obtained by separation, and the first pH value is 2-6;The first nickel precipitation filtrate is adjusted to second pH value, and second nickel precipitation filter cake and second nickel precipitation filtrate are obtained by separation, and the second pH value is 8-12.The method improves the overall recovery rate of nickel in nickel aqueous solution by adopting the way of step-by-step nickel precipitation, while acid leaching treatment can realize the recycling of nickel-containing material to be recycled, improve the degree of resource recovery, and improve the economic benefits of process.

Description

Technical Field

[0001] This invention belongs to the field of catalytic materials technology, and particularly relates to a method for recovering nickel-containing catalysts. Background Technology

[0002] Methods for recovering nickel-containing catalysts include: extraction and oil separation to recover nickel salts, steam deoiling to recover nickel carbonate, and membrane concentration and granulation to recover the catalyst. Patent CN201711043062 discloses a process for recovering stearic acid hydrogenation catalyst, which involves membrane concentration of the catalyst containing hydrogenated oil followed by air-cooled granulation to recover the catalyst. This process involves a long flow and uses a maximum pressure of 2.3 MPa, which places high demands on equipment and safe production.

[0003] Patent CN201610893952 discloses a method for regenerating a deactivated catalyst from the hydrogenation of grease. This method involves degreasing by introducing steam, followed by acid leaching and nickel precipitation to recover nickel carbonate. This process separates the degreasing and acid leaching steps, increasing the number of steps. Furthermore, the direct one-step nickel precipitation method allows impurity ions such as iron, copper, calcium, and magnesium to enter the product, resulting in unsatisfactory product quality.

[0004] Furthermore, the existing technology does not mention methods for treating the separated oil phase, nor does it propose a reasonable disposal plan for the wastewater after nickel precipitation. Therefore, the recovery method for the deactivated catalyst in the hydrogenation of nickel-containing unsaturated fatty acid oils still needs improvement. Summary of the Invention

[0005] This invention addresses the shortcomings of existing technologies by proposing a nickel recovery method. This method improves the overall nickel recovery rate and enhances the economic benefits of the process.

[0006] The technical solution adopted in this invention is as follows: providing a nickel aqueous solution containing nickel ions and impurity ions; adjusting the nickel aqueous solution to a first pH value to separate a first nickel precipitation filter cake and a first nickel precipitation filtrate, wherein the first pH value is 2 to 6; adjusting the first nickel precipitation filtrate to a second pH value to separate a second nickel precipitation filter cake and a second nickel precipitation filtrate, wherein the second pH value is 8 to 12.

[0007] Optionally, in some embodiments of this application, the nickel aqueous solution is prepared by the following steps: nickel-containing material to be recovered, water, and inorganic acid are added to a reaction vessel in a preset ratio, and acid leaching is performed under heating conditions. The reaction is stopped after a preset time. After standing, the upper oil phase is separated through the upper outlet of the reaction vessel, and the mixture of aqueous phase and solid waste remains in the reaction vessel. The mixture of aqueous phase and solid waste is filtered to obtain the nickel aqueous solution and acid-insoluble residue.

[0008] Optionally, in some embodiments of this application, the mass ratio of the nickel-containing material to be recycled to the water is 1:1 to 5.

[0009] Optionally, in some embodiments of this application, the inorganic acid is selected from at least one of hydrochloric acid of a first concentration, sulfuric acid of a second concentration, and nitric acid of a third concentration; the first concentration is 31% to 38%, the second concentration is 90% to 98%, and the third concentration is 60% to 68%; the mass ratio of the nickel-containing material to be recovered to the inorganic acid is 1:1 to 4.

[0010] Optionally, in some embodiments of this application, the heating temperature is 60–90°C, and the heating time is 0.5–2 hours.

[0011] Optionally, in some embodiments of this application, when the impurity ion contains ferrous ions, before adjusting the nickel aqueous solution to a first pH value, the step of adding an oxidant to the nickel aqueous solution for oxidation is further included.

[0012] Optionally, in some embodiments of this application, the oxidant is selected from at least one of hydrogen peroxide, sodium chlorate, sodium hypochlorite, nitric acid, potassium chlorate, potassium permanganate, and ferric chloride.

[0013] Optionally, in some embodiments of this application, the mass ratio of the oxidant to the aqueous nickel solution is 0.2% to 5%.

[0014] Optionally, in some embodiments of this application, the upper oil phase is distilled under reduced pressure to recover the oils and fats in the upper oil phase.

[0015] Optionally, in some embodiments of this application, the acid-insoluble residue is washed with the second nickel leaching filtrate, and the wash water is recycled to replace the water component in the next acid leaching step.

[0016] The nickel recovery method provided by this invention improves the overall nickel recovery rate by employing a stepwise nickel leaching process. Furthermore, through process optimization, the oil separation and acid leaching steps are combined into the same reactor, reducing the number of equipment and enabling the recovery and utilization of the oil phase. In addition, the method proposes using the filtrate from the nickel leaching process to clean acid-insoluble slag and recycling the wash water for use in the acid leaching step, reducing wastewater discharge, improving resource recovery, and enhancing the economic benefits of the process. Attached Figure Description

[0017] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0018] Figure 1 This is a flowchart of the recycling method of the present invention.

[0019] Figure 2This is a process flow diagram of an embodiment of the present invention. Detailed Implementation

[0020] To better understand this invention, specific embodiments are provided below to further illustrate its content. Those skilled in the art should understand that the embodiments described are merely illustrative and not intended to limit the invention. Any modifications and alterations made to this invention within the spirit and scope of the claims fall within the protection scope of this invention.

[0021] A nickel recovery method comprising the following steps:

[0022] A nickel aqueous solution is provided, the nickel aqueous solution containing nickel ions and impurity ions; the nickel aqueous solution is adjusted to a first pH value, and a first nickel precipitation filter cake and a first nickel precipitation filtrate are separated, the first pH value being 2 to 6; the first nickel precipitation filtrate is adjusted to a second pH value, and a second nickel precipitation filter cake and a second nickel precipitation filtrate are separated, the second pH value being 8 to 12.

[0023] This invention adjusts the pH of a nickel aqueous solution to a suitable value through alkali treatment, removing impurity ions in the process. A second alkali treatment followed by separation yields a high-grade nickel-precipitated filter cake. Adjusting the pH of the nickel aqueous solution to 2-6 effectively removes impurity ions such as ferric and copper ions. Further adjusting the pH to 8-12 completely precipitates the nickel ions from the filtrate.

[0024] In one embodiment, the preparation steps of the nickel aqueous solution are as follows: nickel-containing material to be recovered, water, and inorganic acid are added to a reaction vessel in a preset ratio, and acid leaching is performed under heating conditions. The reaction is stopped after a preset time. After settling, the upper oil phase is separated through the upper outlet of the reaction vessel, while the mixture of the aqueous phase and solid waste remains in the reaction vessel. By integrating the oil separation and acid leaching steps into one reaction vessel, the oil separation effect can be achieved simply by opening the outlet on the reaction vessel after the reaction is completed, reducing equipment requirements and shortening the operation process. The mixture of the aqueous phase and solid waste is then filtered to obtain the nickel aqueous solution and acid-insoluble residue.

[0025] In one embodiment, the mass ratio of the nickel-containing material to be recovered to the water is 1:1 to 5 to ensure sufficient contact between the solid and liquid phases.

[0026] In one embodiment, the inorganic acid is selected from at least one of hydrochloric acid of a first concentration, sulfuric acid of a second concentration, and nitric acid of a third concentration; the first concentration is 31% to 38%, the second concentration is 90% to 98%, and the third concentration is 60% to 68%; the mass ratio of the nickel-containing material to be recovered to the inorganic acid is 1:1 to 4 to ensure sufficient contact between the solid and liquid phase materials.

[0027] In one embodiment, the heating temperature is 60–90°C, and the heating time is 0.5–2 hours. Within this temperature and time range, sufficient leaching of nickel can be ensured.

[0028] In one embodiment, when the impurity ions include ferrous ions, the step of adding an oxidant to the nickel aqueous solution for oxidation is further included before adjusting the nickel aqueous solution to a first pH value.

[0029] In one embodiment, the oxidant is selected from at least one of hydrogen peroxide, sodium chlorate, sodium hypochlorite, nitric acid, potassium chlorate, potassium permanganate, and ferric chloride.

[0030] In one embodiment, the mass ratio of the oxidant to the nickel aqueous solution is 0.2% to 5%. The oxidant oxidizes ferrous ions in the nickel aqueous solution to ferric ions. If the amount of oxidant used is too low, the oxidation of ferrous ions will be incomplete; if the amount of oxidant used is too high, it will be wasted.

[0031] In one embodiment, to improve the separation effect of the oil phase, vacuum distillation is used on the upper oil phase to recover the oil and fat in the upper oil phase. The pressure of the vacuum distillation is 0.075–0.09 kPa. After the separated oil phase is separated from inorganic acids and water by the vacuum distillation step, edible-grade oil and fat can be recovered, which not only reduces the cost of outsourcing its waste oil treatment but also increases certain revenue.

[0032] In one embodiment, the second nickel precipitation filtrate is used to wash the acid-insoluble slag, and the wash water is recycled to replace the water component in the next acid leaching step. Using the filtrate generated from the nickel precipitation process to wash the acid-insoluble slag transfers the nickel remaining in the slag to the aqueous phase. The recycled wash water is then used in the acid leaching process, which not only improves the nickel recovery rate but also reduces wastewater disposal costs.

[0033] Example 1

[0034] 100g of spent coconut oil hydrogenation catalyst was mixed with water at a mass ratio of 1:1, and spent catalyst was mixed with hydrochloric acid at a mass ratio of 1:4. The resulting mixture was stirred at 90℃ for 0.5h. The resulting reactants were allowed to stand for 5min, and the upper liquid oil was discharged from the upper outlet of the reactor. The resulting oil was sent to a vacuum distillation apparatus and 24.5g of coconut oil was recovered by vacuum distillation at 0.08kPa.

[0035] The lower aqueous phase and solid waste residue in the reactor were filtered to obtain a nickel aqueous solution and an acid-insoluble residue. 0.5 g of hydrogen peroxide was added to the obtained nickel aqueous solution to oxidize Fe. 2+The pH of the solution was adjusted to 5.01 by consuming 8.52g of 30% liquid alkali. After filtration, the first nickel leaching filtrate and 6.72g of first nickel leaching wet sludge were obtained. 14.59g of 30% liquid alkali was added to the first nickel leaching filtrate to adjust the pH to 11.04. After filtration, the second nickel leaching filtrate and 69.48g of second nickel leaching wet sludge were obtained. The second nickel leaching filtrate was used to wash the acid-insoluble residue, and 183.15g of the wash water was reused in the next acid leaching step instead of the water component.

[0036] Tests showed that the first precipitated nickel sludge contained 1.51% nickel, 33.98% iron, and 24.56% copper, while the second precipitated nickel sludge contained 42.19% nickel. The overall nickel yield was 94.25%, and the coconut oil yield was 77.2%.

[0037] The process flow diagram corresponding to Example 1 is shown below. Figure 2 .

[0038] Example 2

[0039] 100g of spent palm oil hydrogenation catalyst was mixed with water at a mass ratio of 1:5, and spent catalyst was mixed with sulfuric acid at a mass ratio of 1:1. The resulting material was stirred and reacted at 80℃ for 1.5h. The resulting reactants were allowed to stand for 5min, and the upper liquid floating oil was discharged by opening the upper outlet of the reactor. The resulting floating oil was sent to a vacuum distillation apparatus and 24.2g of palm oil was recovered by vacuum distillation at 0.09kPa.

[0040] The lower aqueous phase and solid waste residue in the reactor were filtered to obtain a nickel aqueous solution and an acid-insoluble residue. 7.73g of 30% liquid alkali was used to adjust the pH of the solution to 2.79. After filtration, the first nickel precipitation filtrate and 5.61g of the first nickel precipitation wet sludge were obtained. 15.72g of 30% liquid alkali was added to the first nickel precipitation filtrate to adjust the pH of the solution to 8.89. After filtration, the second nickel precipitation filtrate and 72.11g of the second nickel precipitation wet sludge were obtained. The second nickel precipitation filtrate was used to wash the obtained acid-insoluble residue, and 180.66g of the wash water was reused in the next acid leaching step instead of the water component.

[0041] Tests showed that the first precipitated nickel sludge contained 1.07% nickel and 22.65% copper, while the second precipitated nickel sludge contained 41.80% nickel. The overall nickel yield was 93.97%, and the palm oil yield was 76.8%.

[0042] Example 3

[0043] 100g of spent hydrogenation catalyst for soybean oil was mixed with water at a mass ratio of 1:3 and nitric acid at a mass ratio of 1:2. The resulting mixture was stirred at 60℃ for 2 hours. The resulting reactants were allowed to stand for 5 minutes, and the upper liquid oil was discharged from the upper outlet of the reactor. The resulting oil was sent to a vacuum distillation apparatus and 24.13g of soybean oil was recovered by vacuum distillation at 0.075kPa.

[0044] The lower aqueous phase and solid waste residue in the reactor were filtered to obtain a nickel aqueous solution and an acid-insoluble residue. 2.1 g of sodium hypochlorite was added to the obtained nickel aqueous solution to oxidize Fe. 2+ The pH of the solution was adjusted to 5.95 by consuming 8.08g of 30% liquid alkali. After filtration, the first nickel leaching filtrate and 6.09g of first nickel leaching wet sludge were obtained. 14.38g of 30% liquid alkali was added to the first nickel leaching filtrate to adjust the pH to 11.82. After filtration, the second nickel leaching filtrate and 71.05g of second nickel leaching wet sludge were obtained. The second nickel leaching filtrate was used to wash the acid-insoluble residue, and 185.12g of the wash water was reused in the next acid leaching step instead of the water component.

[0045] Tests showed that the first precipitated nickel sludge contained 1.37% nickel, 31.87% iron, and 20.76% copper, while the second precipitated nickel sludge contained 43.01% nickel. The overall nickel yield was 94.02%, and the soybean oil yield was 76.1%.

Claims

1. A method for recovering nickel, characterized in that, Includes the following steps: An aqueous nickel solution is provided, the aqueous nickel solution containing nickel ions and impurity ions; The nickel aqueous solution is prepared by the following steps: The nickel-containing material to be recovered, water, and inorganic acid are added to a reaction vessel in a preset ratio, and acid leaching is performed under heating conditions. The reaction is stopped after a preset time. The inorganic acid is selected from at least one of hydrochloric acid of a first concentration, sulfuric acid of a second concentration, and nitric acid of a third concentration. The first concentration is 31%–38%, the second concentration is 90%–98%, and the third concentration is 60%–68%. The mass ratio of the nickel-containing material to be recovered to water is 1:1–5, the mass ratio of the nickel-containing material to be recovered to the inorganic acid is 1:1–4, the heating temperature is 60–90°C, and the heating time is 0.5–2 hours. After standing, the upper oil phase is separated from the upper outlet of the reactor, while the mixture of water phase and solid waste remains in the reactor. The mixture of the aqueous phase and solid waste residue was filtered to obtain the nickel aqueous solution and the acid-insoluble residue. The upper oil phase is subjected to vacuum distillation to separate inorganic acids and water and recover edible-grade oils. The pressure of the vacuum distillation is 0.075 to 0.09 kPa. An oxidant is added to the nickel aqueous solution for oxidation; the nickel aqueous solution is adjusted to a first pH value, and the nickel aqueous solution is directly filtered to separate a first nickel precipitation filter cake and a first nickel precipitation filtrate, wherein the first pH value is 2-6; The first nickel precipitate filtrate is adjusted to a second pH value, and the first nickel precipitate filtrate is directly filtered to separate the second nickel precipitate filter cake and the second nickel precipitate filtrate. The second pH value is 8~12.

2. The nickel recovery method according to claim 1, characterized in that, The oxidant is selected from at least one of hydrogen peroxide, sodium chlorate, sodium hypochlorite, nitric acid, potassium chlorate, potassium permanganate, and ferric chloride.

3. The nickel recovery method according to claim 1, characterized in that, The mass ratio of the oxidant to the nickel aqueous solution is 0.2% to 5%.

4. The nickel recovery method according to claim 1, characterized in that, The acid-insoluble residue is washed with the second nickel precipitation filtrate, and the wash water is recycled to replace the water component in the next acid leaching step.

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