Method for removing oil from nickel sulfate solution

Abstract

The invention discloses a method for removing oil from a nickel sulfate solution, which comprises the following steps of: filtering the oil-containing nickel sulfate solution produced by extraction through a multi-bag filter, filtering large-particle impurities in the solution, feeding the filtered solution into a resin column from top to bottom according to a specified flow rate, adsorbing and removing oil by adopting non-polar magnetic composite resin, and feeding the oil-removed solution into the next process through a resin interceptor, when the oil content of the liquid discharged from the resin column is close to the standard requirement of the oil-removed liquid, liquid feeding is stopped, pure water heated to 80-90 DEG C enters the resin column from top to bottom to perform desorption regeneration on the non-polar magnetic composite resin, the oil-containing desorbed liquid can enter an extraction process to be recycled, three wastes are not generated in the process, and the method is simple and easy to implement. The oil content of the oil-removed liquid produced by the process completely meets the oil content standard requirements of the nickel sulfate solution for the ternary precursor.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydrometallurgy of non-ferrous metals, and particularly relates to a method for removing oil from nickel sulfate solution. Background Art

[0002] Nickel sulfate solution is one of the important upstream materials for the production of the cathode material of ternary lithium-ion batteries, and its impurity components directly determine the core physical and chemical properties of the ternary cathode material. During the purification and impurity removal process of nickel sulfate solution, extractants such as light white oil, P204, P507, and C272 are used. These organic substances remain in the nickel sulfate solution after stirring and mixing during the extraction process, which will cause loose morphology, inability to form spheres, broad particle size distribution, and decreased tap density during the precipitation and synthesis of ternary precursors, affecting the quality of ternary precursor products. The traditional process for removing oil from nickel sulfate solution uses "physical clarification in an oil separation tank - ultrasonic and micro-nano air flotation for oil removal - activated carbon adsorption - filtration by a filter press". This oil removal process has a long flow, a large floor area for equipment, requires regular replacement of activated carbon, has a high production and operation cost, and has a low oil removal efficiency. The oil content in the solution after oil removal cannot stably meet the standard requirements of nickel sulfate solution for ternary precursors. For the operation of removing oil from nickel sulfate solution after extraction, in addition to the traditional activated carbon adsorption method, the resin adsorption method for oil removal is also widely used. For example, in the invention patent with the publication number CN201110101239.4, a method for removing oil organic substances from an aqueous solution of nickel compounds is disclosed. The specific oil removal operation is as follows: The nickel compound-containing solution containing oil is passed through a resin adsorption device for oil removal. The resin adsorption device includes a resin layer. The aqueous solution of nickel compound passes through the resin adsorption device from bottom to top, and most of the oil is adsorbed by the resin, gradually forming large oil droplets that automatically converge into an independent oil layer separated from water and float on the upper part of the aqueous solution and are regularly discharged. The nickel sulfate solution produced after resin oil removal is further deeply deoiled by activated carbon to produce qualified nickel sulfate solution. In this oil removal process, only the static adsorption and coalescence function of the resin is utilized. Although it can remove some oil, there is a problem of limited adsorption efficiency, and deep adsorption by activated carbon is still required. A large amount of activated carbon produced needs to be disposed of as hazardous waste, and the resin is not analyzed and regenerated in this patent. As is well known to those skilled in the art, if the resin is not analyzed and regenerated for a long time during the adsorption and oil removal process, the resin will be wrapped by floating oil, resulting in resin caking and then losing its adsorption performance. The oil removal operation disclosed in the invention patent with the publication number CN202410563260.3 is as follows: The oil-containing solution coalesces the dispersed oil in the solution into large oil droplets through a coalescence filter element, and then the oil and water are separated through an oil-water separator. The separated solution enters the resin for oil removal, and the saturated resin is analyzed with ammonia water, and the analysis solution is reused for extraction saponification. As is well known to those skilled in the art, the coalescence of oil through the filter element will cause the filter element to become blocked, requiring a large amount of filter element replacement, increasing the labor intensity of personnel. In addition, the use of acid and alkali solutions during the resin analysis process will cause accelerated resin deterioration, shorten the service life of the resin, and introduce other impurity elements, polluting the oil-containing product solution. The resin types used in the above two inventions are both ordinary macroporous resins, which have no recognition function for specific organic substances such as extractants. During the adsorption process, other organic substances with carbon chains will be adsorbed, thereby reducing their adsorption capacity and unable to achieve the purpose of deep oil removal. Summary of the Invention

[0003] (1) Technical problems to be solved: Aiming at the defects of the existing oil removal process flow being long, the equipment occupying a large area, the need to regularly replace activated carbon, the high production operation cost, the low oil removal efficiency, and the liquid oil content after oil removal being unable to stably meet the standard requirements of nickel sulfate solution for ternary precursors. To solve the above problems, the present invention provides a method for removing oil from nickel sulfate solution. A non-polar magnetic composite resin is selected, which can specifically capture extractants and organic molecule such as P204 / P507 / C272. The oil-containing nickel sulfate solution can effectively separate the oil content therein through resin adsorption, so that it meets the standard requirements of nickel sulfate solution for ternary precursors, without the need for deep oil removal through other auxiliary equipment. The resin desorption and regeneration process uses hot water for desorption, without introducing other impurity elements and generating other waste. The invention has the characteristics of short process, high efficiency, environmental protection, and high economic benefits, and has no impact on the quality of downstream products. It can be applied to industrial production. The method has the advantages of high oil removal depth, no generation of "three wastes", environmental protection and economy.

[0004] (2) The technical solution adopted by the present invention is as follows:

[0005] A method for removing oil from nickel sulfate solution, the method comprising the following steps:

[0006] (1) The oil-containing nickel sulfate produced by extraction is filtered through a multi-bag filter to remove large-particle impurities, and the filtered liquid containing oil is produced;

[0007] (2) The solution produced in step (1) enters the resin column from bottom to top at a specified flow rate. In the resin column, a non-polar magnetic composite resin is used to enrich and adsorb the dissolved oil and extractant in the solution. The resin uses polystyrene as the matrix resin, and a small amount of ferrite particles (nickel ferrite) composed of nickel, iron, and oxygen is added thereto to endow the resin with magnetism, and a silane coupling agent is added to improve the binding property of the magnetic particles and the resin, so that it has excellent mechanical properties and chemical stability. Through functionalization treatment, an amino-containing chelating group is introduced to make the resin have both hydrophobic adsorption and molecular recognition functions. The mass ratio of polystyrene as the matrix resin, ferrite particles and silane coupling agent is 5:2:3, and the ratio has little effect on the oil removal effect, so it can be adjusted according to the actual situation. The suspended oil in the solution is enriched above the resin column bed layer and discharged into the oil collection tank through the oil discharge pipe above the resin column and recycled to the extraction process for utilization. The liquid after resin oil removal is discharged from above the resin column and enters the next process;

[0008] (3) The solution produced in step (2) is filtered through a resin trap and then enters the next process;

[0009] (4) When the oil content in the solution produced in step (2) reaches below 2 ppm, stop the liquid feeding, and use the analytical solution to regenerate the resin in the resin column. The analytical solution enters the resin column from top to bottom, and the post-analytical solution is discharged from the bottom of the resin column.

[0010] (5) When the oil content in the solution produced in step (4) reaches the required value, stop the analysis, and use nitrogen or compressed air to blow out the analytical solution in the resin column. The oil-containing analytical solution enters the extraction process for recycling, and the resin column continues to remove oil from the solution produced in step (1).

[0011] A further technical solution lies in that, in step (1), the oil content in the solution produced by extraction is ≥ 20 mg / L, and the filter bags used in the multi-bag filter are 10 - 20 μm filter bags to intercept impurity particles > 20 μm in the solution.

[0012] A further technical solution lies in that, in step (2), the flow rate of the solution entering the resin column is 1.5 - 2 BV, where BV is the packed volume of the resin in the resin column.

[0013] A further technical solution lies in that, in step (3), the filtering gap of the resin trap is 200 μm, which is used to intercept resins and debris > 200 μm.

[0014] A further technical solution lies in that, in step (4), stop the liquid feeding when the oil content in the produced solution is ≥ 2 mg / L, and the analytical solution uses hot water at 80 - 90 °C. The hot water is sourced from pure water with a conductivity of the pure water ≤ 15 μs / cm.

[0015] A further technical solution lies in that, in step (5), stop the analytical regeneration when the oil content in the solution is ≤ 5 mg / L.

[0016] (3) Due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0017] 1. The oil-containing nickel sulfate solution produced by extraction is filtered through a multi-bag filter. After filtering out large particle impurities in the solution, it enters the resin column from bottom to top at a specified flow rate. The non-polar magnetic composite resin is used to adsorb and remove oil. The post-oil-removal solution enters the next process through the resin interceptor. When the oil content in the effluent of the resin column approaches the standard requirement of the post-oil-removal solution, stop the liquid feeding, and use pure water heated to 80 - 90 °C to enter the resin column from top to bottom to regenerate the non-polar magnetic composite resin. The oil-containing post-analytical solution can enter the extraction process for recycling. No "three wastes" are generated during this process. The oil content of the post-oil-removal solution produced by this process fully meets the oil content standard requirement of the nickel sulfate solution for ternary precursors.

[0018] 2. High degreasing efficiency. For nickel sulfate solution used in ternary precursors, there are relatively high requirements for oil content and organic matter. Compared with traditional degreasing processes, this process has a higher removal efficiency for dissolved oil in the solution, and can reduce the oil content in nickel sulfate solution to less than 2 mg / L, fully meeting the standard requirements for nickel sulfate solution used in ternary precursors.

[0019] 3. Short process flow. This degreasing process uses equipment such as multi-bag filters, resin columns, and resin traps. The equipment occupies a small area and the degreasing process flow is short.

[0020] 4. Low production and operation cost. The non-polar magnetic composite has a service life of 3 - 5 years, and the annual loss is ≤5%. During this period, it can be continuously recycled.

[0021] 5. Green and environmentally friendly. The nickel-containing and oil-containing analytical solution produced by this degreasing process can be reused in the extraction production process again, without generating other hazardous wastes. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is the process flow diagram of the present invention;

[0023] Figure 2 is the connection diagram of series adsorption of resin columns (2 adsorption and 1 regeneration);

[0024] Figure 3 is the operation process diagram of series adsorption of resin columns (2 adsorption and 1 regeneration). DETAILED DESCRIPTION OF THE INVENTION

[0025] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0026] As Figures 1 - 3 shown. A method for degreasing nickel sulfate solution includes the following steps:

[0027] 1. The nickel sulfate solution produced by extraction has the following composition results:

[0028] Analysis of the components of the post-extraction solution

[0029]

[0030] Filter the nickel sulfate solution produced by extraction through a multi-bag filter. The multi-bag filter uses 20 μm filter bags to intercept impurities larger than 20 μm, and avoid large particle impurities from entering the resin column and causing an increase in tower pressure.

[0031] 2. The filtered nickel sulfate solution enters the resin column from bottom to top at a flow rate of 1.5 - 2 BV (BV is the packed volume of the resin column). The non-polar magnetic composite resin packed in the resin column enriches and adsorbs the dissolved oil and extractant in the nickel sulfate solution. The suspended oil in the solution enriches above the resin column bed and is discharged into the oil collection tank through the oil discharge pipeline above the resin column for recycling to the extraction process. The liquid after oil removal from the resin column is discharged from the top of the resin column and enters the next process.

[0032] Analysis of the components of the liquid after resin oil removal

[0033]

[0034] 3. Three resin columns are used for resin oil removal, operating in a mode of 2 adsorption oil removal columns and 1 desorption regeneration column. Among them, the two columns are connected in series at the head and tail for adsorption operation to produce liquid. After adsorption saturation, one column is regenerated, and the other two are connected in series for adsorption to ensure continuous liquid inlet operation of the equipment. The diagram of the operation rotation process is as Figure 2 、 3 shown.

[0035] 4. The liquid after nickel sulfate resin oil removal enters the next process through a resin trap. The filtering gap of the resin trap is 200 μm, which is used to intercept resin and debris larger than 200 μm to prevent resin leakage into the downstream process and affect the product quality of the downstream process.

[0036] 5. When the oil content in the liquid discharged from the resin column ≥ 2 mg / L, stop the liquid inlet, and use pure water at 80 - 90 °C to enter the resin column from top to bottom for desorption regeneration of the non-polar magnetic composite resin. The conductivity of the pure water ≤ 15 μs / cm. After the pure water is heated to 80 - 90 °C by a plate heat exchanger, it enters the resin column from top to bottom for desorption regeneration of the resin. The heating source of the plate heat exchanger comes from production steam.

[0037] 6. When the oil content in the desorbed liquid ≤ 5 ppm, use nitrogen or compressed air to blow the desorbed liquid in the resin column empty, and then continue to adsorb and remove oil from the nickel sulfate solution produced by extraction. The oil-containing desorbed liquid enters the extraction process for recycling.

[0038] The present invention has the following advantages: (1) High defatting efficiency. The nickel sulfate solution for ternary precursors has relatively high requirements for oil content and organic matter. Compared with traditional defatting processes, this process has a higher removal efficiency for dissolved oil in the solution, and can reduce the oil content in the nickel sulfate solution to less than 2 mg / L, fully meeting the standard requirements for nickel sulfate solution for ternary precursors; (2) Short process flow. This defatting process uses equipment such as multi-bag filters, resin columns, and resin traps, with a small floor area and a short defatting process flow; (3) Low production and operation costs. The service life of the non-polar magnetic composite resin is 3-5 years, and the annual loss is ≤5%. During this period, it can be continuously recycled; (4) Green and environmentally friendly. The nickel- and oil-containing desorbed solution produced by this defatting process can be reused in the extraction production process without generating other hazardous wastes. The present invention will be further explained below with specific embodiments.

[0039] Example 1

[0040] The analyzed components of the nickel sulfate solution produced by extraction are as follows:

[0041] Analyzed components of the post-extraction liquid

[0042]

[0043] The packed volume of the resin column is 0.45 m 3 , and the flow rate of the nickel sulfate solution is calculated at 1.5 BV, i.e., 0.7 m 3 / h. The analyzed components of the liquid after resin defatting are as follows:

[0044] Analyzed components of the liquid after resin defatting

[0045]

[0046] The amount of hot water used for desorption is 3.6 m 3 , and the oil content in the final desorbed liquid is 1.9 mg / L.

[0047] Example 2

[0048] The analyzed components of the nickel sulfate solution produced by extraction are as follows:

[0049] Analyzed components of the post-extraction liquid

[0050]

[0051] The packed volume of the resin column is 0.45 m 3 , and the inlet flow rate of the nickel sulfate solution is calculated at 1.8 BV, i.e., 0.8 m 3 / h. The analyzed components of the liquid after resin defatting are as follows:

[0052] Analyzed components of the liquid after resin defatting

[0053]

[0054] Analysis of hot water consumption: 3.15 m 3 , and the oil content in the final effluent of the analysis solution is 3.7 mg / L.

[0055] Example 3

[0056] The analyzed components of the nickel sulfate solution produced by extraction are as follows:

[0057] Analysis of the components of the post-extraction solution

[0058]

[0059] The packed volume of the resin column is 0.45 m 3 , and the inlet flow rate of the nickel sulfate solution is calculated at 2 BV, that is, 0.9 m 3 / h. The analyzed components of the oil-removed solution after passing through the resin are as follows:

[0060] Analysis of the components of the oil-removed solution after passing through the resin

[0061]

[0062] Analysis of hot water consumption: 3.13 m 3 , and the oil content in the final effluent of the analysis solution is 3.3 mg / L.

[0063] The above are only the preferred embodiments of the present invention.

Claims

1. A method for removing oil from nickel sulfate solution, characterized in that, The method described above comprises the following steps: (1) The oil-containing nickel sulfate produced by extraction is filtered through a multi-bag filter to remove large particulate impurities, and the filtered liquid containing oil is produced. (2) The solution produced in step (1) enters the resin column from bottom to top at a specified flow rate. In the resin column, a non-polar magnetic composite resin is used to enrich and adsorb the dissolved oil and extractant in the solution. The non-polar magnetic composite resin uses polystyrene as the matrix resin, and ferrite particles composed of nickel, iron, and oxygen are added thereto, and a silane coupling agent is added. The suspended oil in the solution is enriched above the resin column bed layer and is discharged into the oil collection tank through the oil discharge pipeline above the resin column and recycled to the extraction process for utilization. The deoiled liquid of the resin is discharged from above the resin column and enters the next process. (3) The solution produced in step (2) enters the next process after being filtered by a resin trap. (4) When the oil content of the solution produced in step (2) approaches the standard value of the deoiled liquid, the liquid inlet is stopped, and the resin in the resin column is regenerated by analysis. The analysis liquid enters the resin column from top to bottom, and the analyzed liquid is discharged from below the resin column. (5) When the oil content of the solution produced in step (4) reaches below 2 ppm, the analysis is stopped, and the analysis liquid in the resin column is blown out with nitrogen or compressed air. The oil-containing analysis solution enters the extraction process for recycling, and the resin column continues to enter the solution produced in step (1) for oil removal.

2. The method for degreasing a nickel sulfate solution according to claim 1, characterized in that, In step (1), the oil content of the solution produced by extraction is ≥ 20 mg / L, and the filter bag used in the multi-bag filter is a 10 - 20 μm filter bag to intercept impurity particles > 20 μm in the solution.

3. A method for removing oil from a nickel sulfate solution according to claim 1, characterized in that, In step (2), the flow rate of the solution entering the resin column is 1.5 - 2 BV, where BV is the packed volume of the resin in the resin column.

4. A method for degreasing a nickel sulfate solution according to claim 1, characterized in that, In step (3), the filtration gap of the resin trap is 200 μm, which is used to intercept resins and debris > 200 μm.

5. A method for removing oil from nickel sulfate solution according to claim 1, characterized in that, In step (4), when the oil content of the solution produced is ≥ 2 mg / L, the liquid inlet is stopped. The analysis liquid uses hot water at 80 - 90 °C, and the hot water is sourced from pure water with a conductivity of the pure water ≤ 15 μs / cm.

6. The method for degreasing a nickel sulfate solution according to claim 1, characterized in that, In step (5), when the oil content of the solution is ≤ 5 mg / L, the analysis regeneration is stopped.

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