Deep removal method for basic nickel carbonate sulfate radicals based on multistage countercurrent washing

Abstract

The invention discloses a basic nickel carbonate sulfate radical deep removal method based on multistage countercurrent washing, and belongs to the technical field of chemical engineering, the method realizes efficient and deep removal of sulfate radical ions in basic nickel carbonate by adding a specific additive, optimizing a multistage countercurrent washing system and adding a washing liquid recycling and refining step, and the method is suitable for industrial production. The problem of high sulfate radical content of basic nickel carbonate in the prior art is effectively solved, the production cost and environmental pollution are reduced while the removal rate of the sulfate radicals is increased, and the method has good economic benefits and social benefits.

Description

Technical Field

[0001] The present invention relates to the chemical industry field, and particularly to a method for deeply removing sulfate radicals from nickel basic carbonate based on multi-stage countercurrent washing. Background Art

[0002] Disclosing the information of this background art section is only intended to enhance the overall understanding of the present invention, and it is not necessarily to be regarded as an admission or an implication in any form that this information constitutes the prior art already known to those of ordinary skill in the art.

[0003] Basic carbonates can be applied in the fields of photocatalysis, supercapacitors and secondary batteries; basic carbonates of nickel and cobalt have important applications in the fields of electrode materials, catalysts, additives for electronic materials, magnetic materials, etc. Nickel basic carbonate is an important inorganic fine chemical, mainly used for preparing various nickel salts, and high-quality nickel basic carbonate can be applied in the electronic industry; in addition, nickel basic carbonate is also widely used in electroplating, electroforming, enamel pigments and industrial catalyst industries, etc.

[0004] Sulfate ions are common impurity ions in nickel basic carbonate, and there are many drawbacks in traditional removal methods. For example, although the chemical precipitation method is simple to operate, the precipitation is incomplete, and the sulfate removal rate is low, usually only reaching about 70%-80%; the ion exchange method has a large equipment investment, high operating cost, and the resin regeneration process is complex, and a large amount of wastewater will be generated. In addition, some traditional methods will introduce new impurity ions, affecting the product quality. Therefore, it is urgent to develop a method for deeply removing sulfate radicals from nickel basic carbonate with high efficiency, low cost and environmental protection. Summary of the Invention

[0005] In order to solve the problem of high sulfate radical content in nickel basic carbonate in the prior art, the present invention provides a method for deeply removing sulfate radicals from nickel basic carbonate based on multi-stage countercurrent washing, which improves the purity and performance of the product, and simplifies the process flow and reduces the cost at the same time.

[0006] In order to achieve the above invention purpose, the technical solution of the present invention includes the following steps:

[0007] Step 1: Raw material preparation

[0008] The nickel basic carbonate raw material is preliminarily filtered through a vibrating screen mesh with a screen aperture of 1-3 mm to remove large particle impurities (particle size greater than 3 mm) and unreacted raw materials (such as unreacted nickel salts, carbonates, etc.) therein.

[0009] The filtered nickel basic carbonate raw material is ball-milled. The ball-milling medium is agate balls, the ball-to-material ratio is 5:1 - 10:1, and the ball-milling time is 30 - 60 minutes to obtain nickel basic carbonate powder with a particle size range of 0.05 - 0.5 mm, so as to increase the contact area during the subsequent washing process.

[0010] Step Two: Multi-stage countercurrent washing

[0011] A multi-stage countercurrent washing device is adopted. The device consists of four washing towers connected in series. Each washing tower is internally provided with multiple layers of stirring paddles. The shape of the stirring paddles is a double-layer spiral structure, which can effectively improve the mixing effect of the materials. The tower body is made of stainless steel with a ceramic lining, having good corrosion resistance.

[0012] The pretreated nickel basic carbonate and the washing liquid are subjected to multi-stage countercurrent contact to achieve deep removal of sulfate ions, specifically including:

[0013] The first-stage washing

[0014] The washing liquid is a dilute ammonium sulfate solution containing a specific additive. The additive is sodium citrate, with a mass fraction of 0.5% - 1%, the solution concentration is 0.3 - 0.5 mol / L, and the temperature is controlled at 25 - 35°C.

[0015] The pretreated nickel basic carbonate is fed into the bottom of the first-stage washing tower at a flow rate of 0.8 - 1.2 m 3 / h, and the dilute ammonium sulfate solution is sprayed downward from the top of the first-stage washing tower at a flow rate of 2 - 3 m 3 / h, and the two are in countercurrent contact inside the tower.

[0016] The stirring speed inside the washing tower is set at 80 - 120 r / min, and the washing time is 25 - 30 minutes. During this process, the sodium citrate additive can form a complex with sulfate ions, reducing the activity of sulfate ions, thereby improving its removal efficiency.

[0017] The second-stage washing

[0018] The washing liquid is an ammonium sulfate solution containing a surfactant. The surfactant is sodium dodecylbenzenesulfonate, with a mass fraction of 0.1% - 0.3%, the ammonium sulfate solution concentration is 0.8 - 1.0 mol / L, and the temperature is maintained at 35 - 45°C.

[0019] The nickel basic carbonate after the first-stage washing enters the bottom of the second-stage washing tower at a flow rate of 0.8 - 1.2 m 3 / h, and the ammonium sulfate solution is sprayed downward from the top of the second-stage washing tower at a flow rate of 1.5 - 2 m 3 / h, and the two are in countercurrent contact inside the tower.

[0020] The stirring speed in the washing tower is set to 60-100r / min, and the washing time is 35-40 minutes. The surfactant can reduce the surface tension of the solution, allowing the washing liquid to better penetrate into the basic nickel carbonate particles and further remove sulfate ions.

[0021] Third level washing

[0022] The washing liquid is a high concentration organic ammonium salt solution, such as ammonium acetate solution, with a concentration of 1.2-1.5 mol / L and a temperature controlled at 45-55°C.

[0023] After the second stage washing, the basic nickel carbonate is washed at a flow rate of 0.8-1.2m 3 / h enters the bottom of the third-stage washing tower, and the ammonium acetate solution flows at a flow rate of 1-1.5m 3 / h is sprayed down from the top of the third-stage washing tower, and the two are in countercurrent contact inside the tower.

[0024] The stirring speed in the washing tower is set to 40-80r / min, and the washing time is 45-50 minutes. The organic ammonium salt solution has good complexing ability and can deeply remove the remaining sulfate ions.

[0025] Fourth level washing

[0026] The washing liquid is specially treated deionized water, to which a small amount of EDTA-2Na (disodium ethylenediaminetetraacetate) is added, with a mass fraction of 0.05%-0.1%, for further complexing possible residual metal ions to prevent them from recombining with sulfate ions.

[0027] After the third stage washing, the basic nickel carbonate is washed at a flow rate of 0.8-1.2m 3 / h enters the bottom of the fourth-stage washing tower, and the deionized water flows at a flow rate of 1-1.5m 3 / h is sprayed down from the top of the fourth-stage washing tower, and the two are in countercurrent contact inside the tower.

[0028] The stirring speed in the washing tower is set to 30-60r / min, and the washing time is 50-60 minutes to ensure that the impurities on the surface of the basic nickel carbonate are thoroughly cleaned.

[0029] Step 3: Solid-liquid separation

[0030] The basic nickel carbonate and the washing liquid after multi-stage countercurrent washing are separated into solid and liquid by a disc centrifuge.

[0031] The disc centrifuge is set at a speed of 5000-8000 r / min and a separation factor of 3000-6000 g to ensure efficient separation of basic nickel carbonate solids and washing liquid. Wet basic nickel carbonate solids are obtained by separation.

[0032] IV. Drying Treatment

[0033] Put the wet nickel basic carbonate solid into an oven for drying. The drying temperature is 80 - 120 °C, and the drying time is 8 - 12 hours, so that the moisture content in the solid is reduced to less than 1%, and a low sulfate nickel basic carbonate product is obtained.

[0034] Step V: Recovery of Washing Liquid

[0035] Filter the separated washing liquid through a microporous filter membrane with a pore size of 0.01 - 0.1 μm to remove the solid impurities therein (such as incompletely dissolved salts, fine particles, etc.).

[0036] The filtered washing liquid enters a vacuum concentration device and is concentrated under the conditions of a temperature of 50 - 70 °C and a pressure of 0.03 - 0.08 MPa, and the concentration multiple is 2 - 3 times.

[0037] The concentrated washing liquid is subjected to refining treatment through an ion exchange resin column to remove the trace impurity ions that may be contained therein, and then its various indexes (such as ammonium sulfate content, metal ion content, etc.) are detected. If it meets the requirements, it is recycled for the washing process of the next batch; if it does not meet the requirements, further purification treatment is carried out or the washing liquid is re-prepared.

[0038] The specific embodiments of the present invention have the following beneficial effects:

[0039] (a) Sodium citrate is added to the first-stage washing liquid, and sodium dodecylbenzenesulfonate is added to the second-stage washing liquid. These additives can change the existence state and mass transfer characteristics of sulfate ions and improve their removal efficiency. Compared with the traditional method, the removal rate of sulfate ions can be increased by 15% - 20%.

[0040] (b) A four-stage countercurrent washing system is adopted, and the selection and parameter settings of the washing liquids at each stage are coordinated with each other to gradually and deeply remove sulfate ions. Compared with the traditional two-stage or three-stage washing methods, sulfate ions can be removed more thoroughly, and the sulfate content in the product is reduced to a lower level (lower than 0.01%).

[0041] (c) In the process of washing liquid recovery, an ion exchange resin column refining treatment step is added, which can effectively remove the trace impurity ions that may be contained in the concentrated washing liquid, ensure the quality of the washing liquid and the stability of its recycling use, extend the service life of the washing liquid, and further reduce the cost. Specific Embodiments

[0042] To enable those skilled in the art to better understand the technical solution, the present invention will be described in detail below in conjunction with embodiments. The description in this part is only exemplary and explanatory, and should not have any restrictive effect on the protection scope of the present invention.

[0043] Example 1

[0044] 1. Raw material preparation

[0045] Take 200 kg of nickel basic carbonate raw material, and conduct preliminary filtration through a vibrating sieve with a pore size of 2 mm to remove large particle impurities with a particle size greater than 3 mm and unreacted raw materials.

[0046] Put the filtered nickel basic carbonate raw material into a ball mill for ball milling treatment. The ball milling medium is agate balls, the ball-to-material ratio is 8:1, and the ball milling time is 45 minutes to obtain nickel basic carbonate powder with a particle size range of 0.05 - 0.3 mm.

[0047] 2. Multi-stage countercurrent washing

[0048] First-stage washing

[0049] Feed the pretreated nickel basic carbonate into the bottom of the first-stage washing tower at a flow rate of 1 m 3 / h, and a dilute ammonium sulfate solution containing 0.8% sodium citrate and a concentration of 0.4 mol / L is sprayed downward from the top of the first-stage washing tower at a flow rate of 2.5 m 3 / h.

[0050] Start the stirring device in the first-stage washing tower, set the stirring speed to 100 r / min, control the temperature at 35°C, and collect the nickel basic carbonate after the first-stage washing after 28 minutes of washing.

[0051] Second-stage washing

[0052] Feed the nickel basic carbonate after the first-stage washing into the bottom of the second-stage washing tower at a flow rate of 1 m 3 / h, and a dilute ammonium sulfate solution containing 0.2% sodium dodecylbenzenesulfonate and a concentration of 0.9 mol / L is sprayed downward from the top of the second-stage washing tower at a flow rate of 1.8 m 3 / h.

[0053] Start the stirring device in the second-stage washing tower, set the stirring speed to 80 r / min, control the temperature at 35°C, and collect the nickel basic carbonate after the second-stage washing after 38 minutes of washing.

[0054] Third-stage washing

[0055] Feed the nickel basic carbonate after the second-stage washing into the bottom of the third-stage washing tower at a flow rate of 1 m 3It is fed into the bottom of the third-stage washing tower at a speed of / h, and an ammonium acetate solution with a concentration of 1.3 mol / L is sprayed downward from the top of the third-stage washing tower at a flow rate of 1.2 m 3 / h.

[0056] Start the stirring device in the third-stage washing tower, set the stirring speed to 60 r / min, and after washing for 48 minutes, collect the nickel basic carbonate that has passed through the third-stage washing.

[0057] Fourth-stage washing

[0058] Feed the nickel basic carbonate that has passed through the third-stage washing into the bottom of the fourth-stage washing tower at a flow rate of 1 m 3 / h, and deionized water containing 0.08% EDTA-2Na is sprayed downward from the top of the fourth-stage washing tower at a flow rate of 1.2 m 3 / h.

[0059] Start the stirring device in the fourth-stage washing tower, set the stirring speed to 50 r / min, and after washing for 55 minutes, collect the nickel basic carbonate that has passed through the fourth-stage washing.

[0060] 3. Solid-liquid separation

[0061] Feed the nickel basic carbonate and the washing liquid after multi-stage countercurrent washing into a disc centrifuge for solid-liquid separation at a feed rate of 6 m 3 / h.

[0062] Set the rotation speed of the disc centrifuge to 6500 r / min to obtain wet nickel basic carbonate solid.

[0063] 4. Drying treatment

[0064] Put the wet nickel basic carbonate solid into an oven for drying. The drying temperature is 120 °C and the drying time is 8 hours to reduce the moisture content in the solid to less than 1% to obtain a low-sulfate nickel basic carbonate product. After detection, the sulfate content in the product is 0.008%.

[0065] 5. Recovery of washing liquid

[0066] Filter the separated washing liquid through a microporous filter membrane with a pore size of 0.05 μm to remove the solid impurities therein.

[0067] The filtered washing liquid enters a vacuum concentration device and is concentrated under the conditions of a temperature of 60 °C and a pressure of 0.05 MPa, and the concentration multiple is 2.5 times.

[0068] Example 2

[0069] 1. Raw material preparation

[0070] Take 200 kg of nickel basic carbonate raw material and conduct preliminary filtration through a vibrating sieve with a pore size of 2 mm to remove large particle impurities with a particle size greater than 3 mm and unreacted raw materials.

[0071] Put the filtered nickel basic carbonate raw material into a ball mill for ball milling. The ball milling medium is agate balls, the ball-to-material ratio is 8:1, and the ball milling time is 45 minutes to obtain nickel basic carbonate powder with a particle size range of 0.05 - 0.3 mm.

[0072] 2. Multi-stage countercurrent washing

[0073] First-stage washing

[0074] Feed the pretreated nickel basic carbonate into the bottom of the first-stage washing tower at a flow rate of 0.8 m 3 / h, and a dilute ammonium sulfate solution containing 0.8% sodium citrate and with a concentration of 0.4 mol / L is sprayed downward from the top of the first-stage washing tower at a flow rate of 2 m 3 / h.

[0075] Start the stirring device in the first-stage washing tower, set the stirring speed to 800 r / min, control the temperature at 35°C, and after washing for 25 minutes, collect the nickel basic carbonate after the first-stage washing.

[0076] Second-stage washing

[0077] Feed the nickel basic carbonate after the first-stage washing into the bottom of the second-stage washing tower at a flow rate of 0.8 m 3 / h, and a ammonium sulfate solution containing 0.2% sodium dodecylbenzenesulfonate and with a concentration of 0.9 mol / L is sprayed downward from the top of the second-stage washing tower at a flow rate of 1.5 m 3 / h.

[0078] Start the stirring device in the second-stage washing tower, set the stirring speed to 60 r / min, control the temperature at 35°C, and after washing for 35 minutes, collect the nickel basic carbonate after the second-stage washing.

[0079] Third-stage washing

[0080] Feed the nickel basic carbonate after the second-stage washing into the bottom of the third-stage washing tower at a flow rate of 0.8 m 3 / h, and an ammonium acetate solution with a concentration of 1.2 mol / L is sprayed downward from the top of the third-stage washing tower at a flow rate of 1.0 m 3 / h.

[0081] Start the stirring device in the third-stage washing tower, set the stirring speed to 40 r / min, and after washing for 45 minutes, collect the nickel basic carbonate after the third-stage washing.

[0082] Fourth-stage washing

[0083] The nickel basic carbonate after the third-stage washing is fed into the bottom of the fourth-stage washing tower at a flow rate of 0.8 m 3 / h, and deionized water containing 0.05% EDTA-2Na is sprayed downward from the top of the fourth-stage washing tower at a flow rate of 1.0 m 3 / h.

[0084] Start the stirring device in the fourth-stage washing tower, set the stirring speed to 40 r / min, and after washing for 50 minutes, collect the nickel basic carbonate after the fourth-stage washing.

[0085] 3. Solid-liquid separation

[0086] The nickel basic carbonate and the washing liquid after multi-stage countercurrent washing are fed into a disc centrifuge at a feeding speed of 6 m 3 / h for solid-liquid separation.

[0087] The rotational speed of the disc centrifuge is set to 6000 r / min to obtain wet nickel basic carbonate solid.

[0088] 4. Drying treatment

[0089] Put the wet nickel basic carbonate solid into an oven for drying. The drying temperature is 100 °C and the drying time is 12 hours to reduce the moisture content in the solid to less than 1%, obtaining a low sulfate nickel basic carbonate product. After detection, the sulfate content in the product is 0.009%.

[0090] 5. Recovery of washing liquid

[0091] Filter the separated washing liquid through a microporous filter membrane with a pore size of 0.05 μm to remove the solid impurities therein.

[0092] The filtered washing liquid enters a vacuum concentration device and is concentrated under the conditions of a temperature of 60 °C and a pressure of 0.05 MPa, and the concentration multiple is 2.5 times.

[0093] Example 3

[0094] 1. Raw material preparation

[0095] Take 200 kg of nickel basic carbonate raw material and conduct preliminary filtration through a vibrating screen with a pore size of 2 mm to remove large particle impurities with a particle size greater than 3 mm and unreacted raw materials.

[0096] Put the filtered nickel basic carbonate raw material into a ball mill for ball milling. The ball milling medium is agate balls, the ball-to-material ratio is 8:1, and the ball milling time is 45 minutes to obtain nickel basic carbonate powder with a particle size range of 0.05 - 0.3 mm.

[0097] 2. Multi - stage countercurrent washing

[0098] First - stage washing

[0099] The pretreated basic nickel carbonate is fed into the bottom of the first - stage washing tower at a flow rate of 1.2 m 3 / h. A dilute ammonium sulfate solution containing 0.8% sodium citrate and with a concentration of 0.4 mol / L is sprayed downward from the top of the first - stage washing tower at a flow rate of 3 m 3 / h.

[0100] Start the stirring device in the first - stage washing tower, set the stirring speed to 120 r / min, control the temperature at 35°C. After washing for 30 minutes, collect the basic nickel carbonate that has undergone the first - stage washing.

[0101] Second - stage washing

[0102] The basic nickel carbonate that has undergone the first - stage washing is fed into the bottom of the second - stage washing tower at a flow rate of 1.2 m 3 / h. A dilute ammonium sulfate solution containing 0.2% sodium dodecylbenzenesulfonate and with a concentration of 0.9 mol / L is sprayed downward from the top of the second - stage washing tower at a flow rate of 2 m 3 / h.

[0103] Start the stirring device in the second - stage washing tower, set the stirring speed to 100 r / min, control the temperature at 35°C. After washing for 40 minutes, collect the basic nickel carbonate that has undergone the second - stage washing.

[0104] Third - stage washing

[0105] The basic nickel carbonate that has undergone the second - stage washing is fed into the bottom of the third - stage washing tower at a flow rate of 1.2 m 3 / h. An ammonium acetate solution with a concentration of 1.5 mol / L is sprayed downward from the top of the third - stage washing tower at a flow rate of 1.2 m 3 / h.

[0106] Start the stirring device in the third - stage washing tower, set the stirring speed to 80 r / min. After washing for 50 minutes, collect the basic nickel carbonate that has undergone the third - stage washing.

[0107] Fourth - stage washing

[0108] The basic nickel carbonate that has undergone the third - stage washing is fed into the bottom of the fourth - stage washing tower at a flow rate of 1.2 m 3 / h. Deionized water containing 0.1% EDTA - 2Na is sprayed downward from the top of the fourth - stage washing tower at a flow rate of 1.5 m 3 / h.

[0109] Start the stirring device in the fourth-stage washing tower, set the stirring speed to 60 r / min, and after washing for 60 minutes, collect the nickel basic carbonate that has undergone the fourth-stage washing.

[0110] 3. Solid-liquid separation

[0111] Feed the nickel basic carbonate after multi-stage countercurrent washing and the washing liquid into a disc centrifuge at a feeding speed of 6 m 3 / h for solid-liquid separation.

[0112] Set the rotational speed of the disc centrifuge to 7000 r / min to obtain wet nickel basic carbonate solid.

[0113] 4. Drying treatment

[0114] Put the wet nickel basic carbonate solid into an oven for drying. The drying temperature is 120 °C and the drying time is 8 hours, so that the moisture content in the solid is reduced to less than 1%, and a low sulfate nickel basic carbonate product is obtained. After detection, the sulfate content in the product is 0.007%.

[0115] 5. Recovery of washing liquid

[0116] Filter the separated washing liquid through a microporous filter membrane with a pore size of 0.05 μm to remove the solid impurities therein.

[0117] The filtered washing liquid enters a vacuum concentration device and is concentrated under the conditions of a temperature of 60 °C and a pressure of 0.05 MPa, and the concentration multiple is 2.5 times.

[0118] Comparative example 1

[0119] 1. Raw material preparation

[0120] Take 200 kg of nickel basic carbonate raw material and conduct preliminary filtration through a vibrating screen with a pore size of 2 mm to remove large particle impurities with a particle size greater than 3 mm and unreacted raw materials.

[0121] Put the filtered nickel basic carbonate raw material into a ball mill for ball milling. The ball milling medium is agate balls, the ball-to-material ratio is 8:1, and the ball milling time is 45 minutes to obtain nickel basic carbonate powder with a particle size range of 0.05 - 0.3 mm.

[0122] 2. Multi-stage countercurrent washing

[0123] The first-stage washing

[0124] Feed the pretreated nickel basic carbonate into the bottom of the first-stage washing tower at a flow rate of 1 m 3 / h, and a dilute ammonium sulfate solution containing 0.8% sodium citrate and a concentration of 0.4 mol / L is fed at a flow rate of 2.5 m 3It is sprayed downward from the top of the first-stage washing tower at a speed of / h.

[0125] Start the stirring device in the first-stage washing tower, set the stirring speed to 100 r / min, control the temperature at 35 °C, and after washing for 28 minutes, collect the nickel basic carbonate that has passed through the first-stage washing.

[0126] Second-stage washing

[0127] Feed the nickel basic carbonate that has passed through the first-stage washing into the bottom of the second-stage washing tower at a flow rate of 1 m 3 / h, and the ammonium sulfate solution containing 0.2% sodium dodecylbenzenesulfonate and with a concentration of 0.9 mol / L is sprayed downward from the top of the second-stage washing tower at a flow rate of 1.8 m 3 / h.

[0128] Start the stirring device in the second-stage washing tower, set the stirring speed to 80 r / min, control the temperature at 35 °C, and after washing for 38 minutes, collect the nickel basic carbonate that has passed through the second-stage washing.

[0129] Third-stage washing

[0130] Feed the nickel basic carbonate that has passed through the second-stage washing into the bottom of the third-stage washing tower at a flow rate of 1 m 3 / h, and the ammonium acetate solution with a concentration of 1.3 mol / L is sprayed downward from the top of the third-stage washing tower at a flow rate of 1.2 m 3 / h.

[0131] Start the stirring device in the third-stage washing tower, set the stirring speed to 60 r / min, and after washing for 48 minutes, collect the nickel basic carbonate that has passed through the third-stage washing.

[0132] Fourth-stage washing

[0133] Feed the nickel basic carbonate that has passed through the third-stage washing into the bottom of the fourth-stage washing tower at a flow rate of 1 m 3 / h, and deionized water is sprayed downward from the top of the fourth-stage washing tower at a flow rate of 1.2 m 3 / h.

[0134] Start the stirring device in the fourth-stage washing tower, set the stirring speed to 50 r / min, and after washing for 55 minutes, collect the nickel basic carbonate that has passed through the fourth-stage washing.

[0135] 3. Solid-liquid separation

[0136] Feed the nickel basic carbonate and the washing liquid after multi-stage countercurrent washing into a disc centrifuge at a feeding speed of 6 m 3 / h for solid-liquid separation.

[0137] The rotational speed of the disc centrifuge was set at 6500 r / min to obtain wet nickel basic carbonate solid.

[0138] 4. Drying treatment

[0139] The wet nickel basic carbonate solid was placed in an oven for drying. The drying temperature was 80 - 120 °C and the drying time was 8 - 12 hours, reducing the water content in the solid to less than 1% to obtain a low sulfate nickel basic carbonate product. After testing, the sulfate content in the product was 0.012%.

[0140] 5. Recovery of washing liquid

[0141] The separated washing liquid was filtered through a microporous filter membrane with a pore size of 0.05 μm to remove solid impurities therein.

[0142] The filtered washing liquid entered a vacuum concentration device and was concentrated under the conditions of a temperature of 60 °C and a pressure of 0.05 MPa, with a concentration multiple of 2.5 times.

[0143] Comparative Example 2

[0144] 1. Raw material preparation

[0145] 200 kg of nickel basic carbonate raw material was taken and preliminarily filtered through a vibrating sieve with a pore size of 2 mm to remove large particle impurities with a particle size greater than 3 mm and unreacted raw materials.

[0146] The filtered nickel basic carbonate raw material was put into a ball mill for ball milling. The ball milling medium was agate balls, the ball-to-material ratio was 8:1, and the ball milling time was 45 minutes to obtain nickel basic carbonate powder with a particle size range of 0.05 - 0.3 mm.

[0147] 2. Multistage countercurrent washing

[0148] First-stage washing

[0149] The pretreated nickel basic carbonate was fed into the bottom of the first-stage washing tower at a flow rate of 1 m 3 / h, and a dilute ammonium sulfate solution containing 0.8% sodium citrate and a concentration of 0.4 mol / L was sprayed down from the top of the first-stage washing tower at a flow rate of 2.5 m 3 / h.

[0150] The stirring device in the first-stage washing tower was started, the stirring speed was set at 100 r / min, the temperature was controlled at 35 °C, and after washing for 28 minutes, the nickel basic carbonate after the first-stage washing was collected.

[0151] Second-stage washing

[0152] The nickel basic carbonate after the first-stage washing was fed at a flow rate of 1 m3 It is fed into the bottom of the second-stage washing tower at a speed of 1.8 m / h, and an ammonium sulfate solution containing 0.2% sodium dodecylbenzenesulfonate and with a concentration of 0.9 mol / L is sprayed downward from the top of the second-stage washing tower at a flow rate of 1.8 m 3 / h.

[0153] Start the stirring device in the second-stage washing tower, set the stirring speed to 80 r / min, control the temperature at 35 °C, and after washing for 38 minutes, collect the nickel basic carbonate after the second-stage washing.

[0154] Third-stage washing

[0155] Feed the nickel basic carbonate after the second-stage washing into the bottom of the third-stage washing tower at a flow rate of 1 m 3 / h, and deionized water containing 0.08% EDTA-2Na is sprayed downward from the top of the third-stage washing tower at a flow rate of 1.2 m 3 / h.

[0156] Start the stirring device in the third-stage washing tower, set the stirring speed to 50 r / min, and after washing for 55 minutes, collect the nickel basic carbonate after the third-stage washing.

[0157] 3. Solid-liquid separation

[0158] Feed the nickel basic carbonate and the washing liquid after multi-stage countercurrent washing into a disc centrifuge at a feed rate of 6 m 3 / h for solid-liquid separation.

[0159] Set the rotation speed of the disc centrifuge to 6500 r / min to obtain wet nickel basic carbonate solid.

[0160] 4. Drying treatment

[0161] Put the wet nickel basic carbonate solid into an oven for drying. The drying temperature is 80 - 120 °C, and the drying time is 8 - 12 hours to reduce the moisture content in the solid to less than 1% to obtain a low-sulfate nickel basic carbonate product. After detection, the sulfate content in the product is 0.013%.

[0162] 5. Recovery of washing liquid

[0163] Filter the separated washing liquid through a microporous filter membrane with a pore size of 0.05 μm to remove the solid impurities therein.

[0164] The filtered washing liquid enters a vacuum concentration device and is concentrated under the conditions of a temperature of 60 °C and a pressure of 0.05 MPa, and the concentration multiple is 2.5 times.

[0165] Comparative Example 3

[0166] 1. Raw material preparation

[0167] Take 200 kg of nickel carbonate hydroxide raw material and conduct preliminary filtration through a vibrating sieve with a pore size of 2 mm to remove large particle impurities with a particle size greater than 3 mm and unreacted raw materials.

[0168] Put the filtered nickel carbonate hydroxide raw material into a ball mill for ball milling. The ball milling medium is agate balls, the ball-to-material ratio is 8:1, and the ball milling time is 45 minutes to obtain nickel carbonate hydroxide powder with a particle size range of 0.05 - 0.3 mm.

[0169] 2. Multi-stage countercurrent washing

[0170] First-stage washing

[0171] Feed the pretreated nickel carbonate hydroxide into the bottom of the first-stage washing tower at a flow rate of 1 m 3 / h, and a dilute ammonium sulfate solution containing 0.8% sodium citrate and a concentration of 0.4 mol / L is sprayed downward from the top of the first-stage washing tower at a flow rate of 2.5 m 3 / h.

[0172] Start the stirring device in the first-stage washing tower, set the stirring speed to 100 r / min, control the temperature at 35°C, and collect the nickel carbonate hydroxide after the first-stage washing after 28 minutes of washing.

[0173] Second-stage washing

[0174] Feed the nickel carbonate hydroxide after the first-stage washing into the bottom of the second-stage washing tower at a flow rate of 1 m 3 / h, and a dilute ammonium sulfate solution containing 0.2% sodium dodecylbenzenesulfonate and a concentration of 0.9 mol / L is sprayed downward from the top of the second-stage washing tower at a flow rate of 1.8 m 3 / h.

[0175] Start the stirring device in the second-stage washing tower, set the stirring speed to 80 r / min, control the temperature at 35°C, and collect the nickel carbonate hydroxide after the second-stage washing after 38 minutes of washing.

[0176] Third-stage washing

[0177] Feed the nickel carbonate hydroxide after the second-stage washing into the bottom of the third-stage washing tower at a flow rate of 1 m 3 / h, and deionized water is sprayed downward from the top of the third-stage washing tower at a flow rate of 1.2 m 3 / h.

[0178] Start the stirring device in the third-stage washing tower, set the stirring speed to 60 r / min, and collect the nickel carbonate hydroxide after the third-stage washing after 48 minutes of washing.

[0179] 3. Solid-liquid separation

[0180] The nickel basic carbonate after multi-stage countercurrent washing and the washing liquid are fed into a disc centrifuge at a feeding rate of 6 m 3 / h for solid-liquid separation.

[0181] The rotational speed of the disc centrifuge is set at 6500 r / min to obtain wet nickel basic carbonate solid.

[0182] 4. Drying treatment

[0183] The wet nickel basic carbonate solid is placed in an oven for drying. The drying temperature is 80 - 120 °C and the drying time is 8 - 12 hours to reduce the moisture content in the solid to less than 1%, obtaining a low sulfate nickel basic carbonate product. After detection, the sulfate content in the product is 0.015%.

[0184] 5. Recovery of washing liquid

[0185] The separated washing liquid is filtered through a microporous filter membrane with a pore size of 0.05 μm to remove solid impurities therein.

[0186] The filtered washing liquid enters a vacuum concentration device and is concentrated under the conditions of a temperature of 60 °C and a pressure of 0.05 MPa, and the concentration multiple is 2.5 times.

[0187] Comparative Example 4

[0188] 1. Raw material preparation

[0189] Take 200 kg of nickel basic carbonate raw material and conduct preliminary filtration through a vibrating screen with a pore size of 2 mm to remove large particle impurities with a particle size greater than 3 mm and unreacted raw materials.

[0190] The filtered nickel basic carbonate raw material is put into a ball mill for ball milling. The ball milling medium is agate balls, the ball-to-material ratio is 8:1, and the ball milling time is 45 minutes to obtain nickel basic carbonate powder with a particle size range of 0.05 - 0.3 mm.

[0191] 2. Multi-stage countercurrent washing

[0192] The first-stage washing

[0193] The pretreated nickel basic carbonate is fed into the bottom of the first-stage washing tower at a flow rate of 1 m 3 / h, and deionized water is sprayed down from the top of the first-stage washing tower at a flow rate of 2.5 m 3 / h.

[0194] Start the stirring device in the first-stage washing tower, set the stirring speed to 100 r / min, control the temperature at 35 °C, and after washing for 28 minutes, collect the nickel basic carbonate after the first-stage washing.

[0195] Second-stage washing

[0196] Feed the nickel basic carbonate after the first-stage washing into the bottom of the second-stage washing tower at a flow rate of 1 m 3 / h, and deionized water is sprayed downward from the top of the second-stage washing tower at a flow rate of 1.8 m 3 / h.

[0197] Start the stirring device in the second-stage washing tower, set the stirring speed to 80 r / min, control the temperature at 35 °C, and after washing for 38 minutes, collect the nickel basic carbonate after the second-stage washing.

[0198] Third-stage washing

[0199] Feed the nickel basic carbonate after the second-stage washing into the bottom of the third-stage washing tower at a flow rate of 1 m 3 / h, and deionized water is sprayed downward from the top of the third-stage washing tower at a rate of 1.2 m 3 / h.

[0200] Start the stirring device in the third-stage washing tower, set the stirring speed to 60 r / min, and after washing for 48 minutes, collect the nickel basic carbonate after the third-stage washing.

[0201] Fourth-stage washing

[0202] Feed the nickel basic carbonate after the third-stage washing into the bottom of the fourth-stage washing tower at a flow rate of 1 m 3 / h, and deionized water is sprayed downward from the top of the fourth-stage washing tower at a flow rate of 1.2 m 3 / h.

[0203] Start the stirring device in the fourth-stage washing tower, set the stirring speed to 50 r / min, and after washing for 55 minutes, collect the nickel basic carbonate after the fourth-stage washing.

[0204] 3. Solid-liquid separation

[0205] Feed the nickel basic carbonate and the washing liquid after multi-stage countercurrent washing into a disc centrifuge for solid-liquid separation at a feeding speed of 6 m 3 / h.

[0206] Set the rotation speed of the disc centrifuge to 6500 r / min to obtain wet nickel basic carbonate solid.

[0207] 4. Drying treatment

[0208] The wet nickel basic carbonate solid is placed in an oven for drying. The drying temperature is 80 - 120 °C, and the drying time is 8 - 12 hours, so that the moisture content in the solid is reduced to less than 1%, and a low sulfate nickel basic carbonate product is obtained. After detection, the sulfate content in the product is 0.05%.

[0209] 5. Recovery of washing liquid

[0210] The separated washing liquid is filtered through a microporous filter membrane with a pore size of 0.05 μm to remove the solid impurities therein.

[0211] The filtered washing liquid enters a vacuum concentration device and is concentrated under the conditions of a temperature of 60 °C and a pressure of 0.05 MPa, and the concentration multiple is 2.5 times.

[0212] Comparative Example 5

[0213] 1. Raw material preparation

[0214] Take 200 kg of nickel basic carbonate raw material and conduct preliminary filtration through a vibrating screen with a pore size of 2 mm to remove large particle impurities with a particle size greater than 3 mm and unreacted raw materials.

[0215] The filtered nickel basic carbonate raw material is put into a ball mill for ball milling. The ball milling medium is agate balls, the ball-to-material ratio is 8:1, and the ball milling time is 45 minutes to obtain nickel basic carbonate powder with a particle size range of 0.05 - 0.3 mm.

[0216] 2. Multi-stage countercurrent washing

[0217] First-stage washing

[0218] The pretreated nickel basic carbonate is fed into the bottom of the first-stage washing tower at a flow rate of 1 m 3 / h, and a dilute ammonium sulfate solution containing 0.8% sodium citrate and a concentration of 0.4 mol / L is sprayed from the top of the first-stage washing tower at a flow rate of 2.5 m 3 / h.

[0219] Start the stirring device in the first-stage washing tower, set the stirring speed to 100 r / min, control the temperature at 35 °C, and after washing for 28 minutes, collect the nickel basic carbonate that has undergone the first-stage washing.

[0220] Second-stage washing

[0221] The nickel basic carbonate that has undergone the first-stage washing is fed into the bottom of the second-stage washing tower at a flow rate of 1 m 3 / h, and a dilute ammonium sulfate solution containing 0.2% sodium dodecylbenzenesulfonate and a concentration of 0.9 mol / L is sprayed from the top of the second-stage washing tower at a flow rate of 1.8 m 3 / h.

[0222] Start the stirring device in the second-stage scrubbing tower, set the stirring speed to 80 r / min, control the temperature at 35 °C, and after scrubbing for 38 minutes, collect the nickel basic carbonate that has undergone the second-stage scrubbing.

[0223] 3. Solid-liquid separation

[0224] Feed the nickel basic carbonate and the washing liquid after multi-stage countercurrent scrubbing into a disc centrifuge at a feeding speed of 6 m3 / h for solid-liquid separation.

[0225] Set the rotational speed of the disc centrifuge to 6500 r / min to obtain wet nickel basic carbonate solid.

[0226] 4. Drying treatment

[0227] Put the wet nickel basic carbonate solid into an oven for drying. The drying temperature is 80 - 120 °C, and the drying time is 8 - 12 hours to reduce the moisture content in the solid to less than 1%, obtaining a low-sulfate nickel basic carbonate product. After detection, the sulfate content in the product is 0.025%.

[0228] 5. Recovery of washing liquid

[0229] Filter the separated washing liquid through a microporous filter membrane with a pore size of 0.05 μm to remove the solid impurities therein.

[0230] The filtered washing liquid enters a vacuum concentration device and is concentrated under the conditions of a temperature of 60 °C and a pressure of 0.05 MPa, with a concentration multiple of 2.5 times.

[0231] It should be noted that in this article, the terms: including, containing and any other variants are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such a process, method, article or device. Specific examples are used in this article to elaborate on the principles and implementation methods of the technical solutions of the present invention. The description of the above examples is only used to help understand the method of the present invention and its core idea. The above is only the preferred implementation method of the present invention. It should be pointed out that due to the limited nature of literal expression and objectively existing infinite specific structures, for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements, modifications or changes can be made, or the above technical features can be combined in an appropriate manner; these improvements, modifications, changes or combinations, or directly applying the concept and technical solution of the present invention to other occasions without improvement, should all be regarded as the protection scope of the present invention.

Claims

1. A method for preparing basic nickel carbonate with low sulfate radical by using ammonium carbonate to replace sodium carbonate, which is characterized in that, It includes the following steps: S1. Raw material preparation, pre-treating the nickel basic carbonate raw material; S2. Multi-stage countercurrent washing; S3. Solid-liquid separation, and centrifugal separation is adopted for the solid-liquid separation; S4. Drying treatment; S5. Recovery of washing liquid; The multi-stage countercurrent washing is four-stage washing. The washing liquid for the first-stage washing is a dilute ammonium sulfate solution containing sodium citrate; The washing liquid for the second-stage washing is an ammonium sulfate solution containing sodium dodecylbenzenesulfonate; The washing liquid for the third-stage washing is an ammonium acetate solution; the washing liquid for the fourth-stage washing is deionized water containing EDTA-2Na.

2. The method according to claim 1, wherein In step S1, the pre-treatment is filtration and ball milling.

3. The method according to claim 2, characterized in that, In step S1, the ball milling medium is agate balls, the ball-to-material ratio is 8:1, and the ball milling time is 45 minutes.

4. The method according to claim 1, wherein In step S2, the first-stage washing liquid is a dilute ammonium sulfate solution containing 0.5%-1% sodium citrate and with a concentration of 0.3-0.5 mol / L.

5. The method according to claim 1, wherein In step S2, the second-stage washing liquid is an ammonium sulfate solution containing 0.1%-0.3% sodium dodecylbenzenesulfonate and with a concentration of 0.8-1.0 mol / L.

6. The method according to claim 1, characterized in that, In step S2, the third-stage washing liquid is an ammonium acetate solution with a concentration of 1.2-1.5 mol / L.

7. The method according to claim 1, characterized in that In step S2, the fourth-stage washing liquid is deionized water containing 0.05%-0.1% EDTA-2Na.

8. The method according to claim 1, wherein In step S3, the centrifugal speed is set at 5000-8000 r / min.

9. The method according to claim 1, characterized in that In step S4, the drying temperature is 80-120 °C, and the drying time is 8-12 hours, so that the water content in the solid is reduced to less than 1%.