Method for efficiently preparing nickel sulfate solution from high-nickel matte

Abstract

The invention relates to a method for efficiently preparing a nickel sulfate solution from high-nickel matte, and belongs to the technical field of hydrometallurgy. According to the method, the high-nickel matte raw material is fully leached by combining two-stage normal-pressure leaching and one-stage pressure leaching with a CCD three-stage countercurrent washing process, so that the problems of insufficient batching precision, low leaching rate, high impurity content, high energy consumption and the like in the prior art are effectively solved, and the production targets of low energy consumption and low pollution are achieved. Specifically, a liquid preparation procedure is added in a normal-pressure leaching stage, key process parameters such as liquid-solid ratio, concentration and acidity are accurately controlled, and the problem of open circuit of iron and sulfur in a system is solved; copper sulfate is added into the second-section normal-pressure size mixing tank, so that generation and dissipation of hydrogen sulfide gas are effectively inhibited and eliminated; and finally, the leaching residues are fully washed through a CCD washing technology, the recovery rate of nickel and cobalt metal is remarkably increased, and efficient utilization of resources is achieved.

Description

Technical Field

[0001] This invention relates to the field of non-ferrous metal hydrometallurgy, and more specifically to a method for efficiently preparing nickel sulfate solution using high-nickel matte. Background Art

[0002] In recent years, with the rapid development of new energy vehicles and energy storage technologies, the market demand for high-performance, high-purity battery-grade nickel sulfate has continued to rise. Due to its excellent characteristics such as high energy density and long cycle life, battery-grade nickel sulfate has been widely used in power batteries and energy storage batteries.

[0003] Currently, the main production processes for nickel sulfate include: 1. High-nickel matte pressure leaching method: selective leaching of high-nickel matte with a nickel content ≥70%, achieving efficient nickel leaching (leaching rate >98%) and deep separation of impurities such as iron and copper; 2. Nickel briquettes / nickel powder acid dissolution method: short process flow (only two steps: dissolution and crystallization), high product purity (up to 4N grade); 3. Nickel-cobalt hydroxide (MHP) conversion method: using MHP, an intermediate product of laterite nickel ore high-pressure acid leaching (HPAL), as raw material, and preparing it through a resolution-purification process; 4. Ternary lithium battery black powder recovery method: selective leaching of the positive electrode black powder of retired power batteries using a sulfuric acid system to achieve the synergistic recovery of nickel, cobalt, and manganese.

[0004] Among these methods, the nickel briquettes / nickel powder acid leaching method, while simple and capable of directly producing high-purity nickel sulfate, suffers from high raw material costs and poor economic viability. The nickel-cobalt hydroxide (MHP) conversion method easily introduces impurities such as aluminum, manganese, and magnesium, significantly increasing the difficulty and burden of subsequent extraction and impurity removal. While the ternary black powder recovery process aligns with the circular economy concept, it faces technical bottlenecks such as difficulties in decomposing organic binders and low average metal recovery rates. Therefore, utilizing pressure leaching to process high-nickel matte to produce high-quality nickel sulfate solutions has become an important development direction in the field of hydrometallurgy both domestically and internationally. Summary of the Invention

[0005] The purpose of this invention is to provide a low-cost and streamlined method for producing nickel sulfate from high-nickel matte. This method significantly improves the leaching rates of nickel and cobalt by precisely controlling the compressed air flow, reaction temperature, and pressure during the leaching process, and by adding copper sulfate in the second-stage atmospheric pressure leaching step. Simultaneously, it effectively solves the open-circuit problem of iron in the system, reduces the iron content in the leachate, and suppresses the generation and escape of hydrogen sulfide gas, thereby enhancing production safety.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for efficiently preparing nickel sulfate solution using high-nickel matte includes the following steps: 1. Grinding stage: After the high-nickel matte raw material is ground twice, first by a ball mill and then by a vertical mill, the slurry is pumped into a first-stage slurry conditioning tank; 2. First stage at atmospheric pressure: Add industrial water, sulfuric acid, and supernatant from a pressure thickener to the first-stage acid mixing tank, mix thoroughly, and then pump into the first-stage slurry preparation tank; pump the slurry from the preparation tank into the first-stage atmospheric pressure leaching tank, and introduce compressed air at a flow rate of approximately 800~1200 Nm³. 3 The reaction is carried out at a temperature of approximately 75-85℃ for approximately 8-10 hours, with one pass of atmospheric pressure leaching. The underflow from leaching tank #7 is pumped into a first-stage atmospheric pressure thickener. The thickener concentrates and separates the supernatant and underflow. The supernatant is then filtered to obtain a nickel sulfate solution, the main components of which are Ni: 110-120 g / L, Co: 1.35-1.5 g / L, Fe ≤ 0.01 g / L, S: ≤ 0.02 g / L, and pH 5.5-6.0. 3. Second-stage atmospheric pressure: The underflow obtained from the first-stage atmospheric pressure leaching and thickening separation is pumped into the second-stage slurry preparation tank, and concentrated sulfuric acid, industrial water, wastewater, and CCD washing thickener supernatant are added to obtain the second-stage atmospheric pressure slurry. This slurry is then pumped into the second-stage atmospheric pressure leaching tank, and compressed air is introduced at a flow rate of approximately 800–1200 Nm³. 3 / h. stage, reaction temperature about 75~85℃, reaction time about 8~10h, to obtain two-stage atmospheric pressure leachate; 4. Pressure leaching: The second-stage atmospheric pressure leachate is pumped into a pressure vessel and oxygen is introduced for pressure leaching. The pressure leaching solution is sent to a pressure thickener for separation to obtain supernatant and underflow. The supernatant is the pressure leaching solution, which is pumped to the first-stage acid preparation tank for adjusting the first-stage slurry solution. The underflow is pumped into the second-stage slurry preparation tank. 5. CCD Washing: The underflow obtained from the pressure leaching stage is pumped into a CCD primary washing and thickening machine. Its supernatant is used for slurrying the filter residue in step 2 of claim and for slurry conditioning in step 3 of claim. The underflow is then pumped into a CCD secondary washing and thickening machine. The supernatant from the CCD secondary thickening machine is pumped into the CCD primary washing and thickening machine, and the underflow is pumped into a CCD tertiary washing and thickening machine. The supernatant from the CCD tertiary washing and thickening machine is pumped into the CCD secondary washing and thickening machine. The underflow is filtered to obtain a low-nickel, high-iron leaching tailings, the main components of which are nickel ≤3.5%, cobalt ≤0.05%, iron ≥45%, and copper ≥0.2%. Based on this technical solution, a three-stage CCD countercurrent washing process, consisting of two stages of atmospheric pressure leaching, one stage of pressurized leaching, and a complete leaching process, can fully leach nickel from the raw materials, yielding a high-nickel, low-impurity nickel sulfate solution. Furthermore, the added solution preparation process allows for real-time adjustment and stabilization of key parameters such as the liquid-to-solid ratio, concentration, and acidity of the slurry, significantly improving process adaptability and enabling effective processing of various complex nickel raw materials, successfully leaching nickel alloy phases, Ni3S2, NiS, and other phases. While ensuring high direct recovery rates of nickel and cobalt, this solution achieves the hydrolysis and oxidation precipitation of copper and iron elements through precise control of the process parameters (such as pH value and compressed air flux) in the two stages of atmospheric pressure leaching, resulting in copper and iron key impurity contents in the nickel sulfate solution both below 0.01 g / L.

[0007] The reaction mechanisms of each process are as follows: 1. Main reactions of atmospheric pressure leaching Ni + CuSO4 = NiSO4 + Cu↓ Fe + CuSO4 = FeSO4 + Cu↓ Ni + H₂SO₄ = NiSO₄ + H₂↑ Fe + H₂SO₄ = FeSO₄ + H₂↑ 2Cu + O₂ = 2CuO↓ CuO + H₂SO₄ = CuSO₄ + H₂O 2FeSO4+ 0.5O2+H2SO4= Fe2(SO4)3+H2O Fe2(SO4)3+3H2O= 3H2SO4+FeOOH(Fe2O3·H2O)↓ When the pH value is greater than 4.1, copper hydrolysis will also occur: 3 CuSO4+4 H2O= CuSO4·2Cu(OH)2↓+2H2SO4 Other possible reactions: Ni2S3+ H2SO4+ 0.5O2= NiS↓+ NiSO4+H2O In a normal-pressure leaching stage, a pressure leaching solution (low pH, containing copper and iron) undergoes a displacement reaction with the alloy phase in the raw material, achieving acid reduction and copper removal. As the pH of the reaction system gradually increases, copper ions undergo hydrolysis, precipitating as basic copper sulfate in the slag phase. Simultaneously, under the action of compressed air, ferrous iron in the solution is oxidized, generating iron oxide (FeOOH) precipitate, which is enriched in the slag phase. The synergistic effect of these reactions ultimately produces a high-nickel, low-impurity nickel sulfate solution.

[0008] 2. Main reactions of two-stage atmospheric pressure leaching Ni + H₂SO₄ = NiSO₄ + H₂↑ Fe + H₂SO₄ = FeSO₄ + H₂↑ 2FeSO4+ 0.5O2+H2SO4= Fe2(SO4)3+H2O Fe2(SO4)3+3H2O= 3H2SO4+FeOOH(Fe2O3·H2O)↓ Ni2S3+ H2SO4+ 0.5O2= NiS↓+ NiSO4+H2O NiS + H₂SO₄ = H₂S↑ + NiSO₄ H₂S + CuSO₄ = CuS↓ + H₂SO₄ The primary purpose of the second-stage atmospheric pressure leaching is to provide a suitable slurry for the pressurized stage. This solution has a high acidity, and any unreacted alloy phases from the first-stage atmospheric pressure leaching react with nickel sulfide in the material to form nickel sulfate. Additionally, FeS, some NiS, and CoS react with sulfuric acid to generate hydrogen sulfide gas. Therefore, copper sulfate needs to be added periodically to suppress the hydrogen sulfide gas.

[0009] 3. Main reactions of pressure leaching Ni2S3+ H2SO4+ 0.5O2= NiS↓+ NiSO4+H2O MeS + H2SO4 = MeSO4 + H2S↑ (where Me represents Ni, Fe, Cu, Co, etc.) H₂S + 2O₂ = H₂SO₄ 2FeSO4+ 0.5O2+H2SO4= Fe2(SO4)3+H2O Fe2(SO4)3+3H2O= 3H2SO4+ Fe2O3↓ If the mineral contains Ni3As2, the following reaction may also occur: Ni3As2+ 3H2SO4= 2AsH3↑+3NiSO4 2AsH3 + 3O2 = As2O3↓ + H2O In addition, an important reaction also occurs during pressure leaching: MeS+ Fe2(SO4)3= MeSO4+2FeSO4+S↓ The purpose of pressure leaching is to maximize the leaching rate of nickel and cobalt. Simultaneously, the copper in the leached portion is supplied to a section under normal pressure to displace the alloy phase in the raw material, suppressing most of the copper in the leaching residue and ensuring a Cu content in the leaching system. 2+ / Cu +The cyclic balance achieves selective leaching. Under an oxidizing atmosphere, almost all sulfides in the raw material are leached out, NiS and the last remaining Ni3S2 displace copper sulfide and chalcocite, while iron is oxidized to iron oxide and remains in the slag, thus achieving an open path for copper, iron, and sulfur. Attached Figure Description

[0010] Figure 1 This is a process flow diagram of a method for efficiently preparing nickel sulfate solution using high-nickel matte according to the present invention. Detailed Implementation

[0011] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0012] The high-nickel matte composition in this embodiment is shown in Table 1.

[0013] Table 1. Composition of high-nickel matte (wt%) element Ni Co Cu Fe S wt% 74.35 0.69 0.15 2.26 10.45 Example 1 A method for efficiently preparing nickel sulfate solution using high-nickel matte includes the following steps: Step 1: The high-nickel matte bale is hoisted to the automatic feeding system. After breaking the bale, the material is conveyed to the ball mill via belt and ground with fresh water. The ball mill discharge concentration is 75%. The ball mill slurry is then ground in a vertical mill, with a discharge concentration of 35%. The overflow fineness of the vertical mill (-280 mesh ≥ 90%) is pumped into the first-stage atmospheric pressure slurry conditioning tank. Concentrated sulfuric acid, industrial water, and supernatant from a pressure thickener are pumped into the first-stage atmospheric pressure acid mixing tank to ensure a pH of 4.0-4.5. After mixing, the mixture is pumped into the first-stage atmospheric pressure slurry conditioning tank for slurry preparation. When the liquid level reaches 50% or higher, it can be fed into the first-stage atmospheric pressure leaching tank. The slurry is pumped into the first-stage atmospheric pressure leaching tank for atmospheric pressure leaching. The leaching tank temperature is 80℃, and 800 Nm of compressed air is introduced. 3 The leaching time is 8 hours per stage. The leachate is pumped to an atmospheric pressure thickener for concentration and separation, yielding a supernatant and underflow. The underflow is pumped into a second-stage atmospheric pressure slurry conditioning tank, and the supernatant is filtered through a filter press to obtain the product, nickel sulfate solution. Its specific composition is: nickel 112.32 g / L; copper 0.0032 g / L; iron 0.0024 g / L; cobalt 1.46 g / L; lead 0.00043 g / L; zinc 0.0035 g / L; arsenic 0.00032 g / L; pH value 5.5. Step 2: Pump the supernatant from the CCD primary washing thickener, concentrated sulfuric acid, and industrial water / wastewater into the secondary atmospheric pressure acid mixing tank to prepare the solution, ensuring a pH of 0.5~1.0. After mixing, pump the solution into the secondary atmospheric pressure slurry preparation tank and mix it with the underflow from the primary atmospheric pressure leaching thickener for slurrying. When the liquid level reaches 50% or higher, feed material into the secondary atmospheric pressure leaching tank for secondary atmospheric pressure leaching. The leaching tank temperature is 78℃, and compressed air at 850 Nm³ is introduced. 3 / h·stage, leaching time is 8h, pH of the leaching solution after the second stage is 1.0~2.0; Step 3: The second-stage atmospheric pressure leaching slurry is pumped into a pressure vessel, and oxygen is introduced to carry out the pressure leaching reaction. The oxygen flow rate during pressure leaching is 1000 Nm³. 3 The leaching process was carried out at a pressure of 1.2 MPa, a temperature of 170°C, and a pH of 2.0 for 6 hours per unit. After cooling and depressurization in a flash evaporator, the product was concentrated and separated in a thickener to obtain supernatant and underflow. The supernatant was pumped into a first-stage atmospheric pressure acid mixing tank, and the underflow was pumped into a CCD primary washing thickener. Step 4: The supernatant from the CCD primary washing and thickening machine is used to slurry the first-stage atmospheric pressure filter residue or to supply the second-stage atmospheric pressure acid mixing tank. The underflow from the primary machine is pumped into the CCD secondary washing and thickening machine. The supernatant from the secondary machine is pumped into the CCD primary washing and thickening machine. The underflow is then pumped into the CCD tertiary washing and thickening machine. Industrial water is added to the tertiary thickening machine to wash the leaching residue. The supernatant from the tertiary thickening machine is pumped into the secondary washing and thickening machine. The underflow from the CCD tertiary thickening machine is filtered to obtain the leaching tailings. Its specific composition is: nickel 3.14%, cobalt 0.032%, iron 47.99%, and copper 1.46%.

[0014] Example 2 A method for efficiently preparing nickel sulfate solution using high-nickel matte includes the following steps: Step 1: The high-nickel matte bale is hoisted to the automatic feeding system. After breaking the bale, the material is conveyed to the ball mill via belt and ground with fresh water. The ball mill discharge concentration is 78%. The ball mill slurry is then ground in a vertical mill, with a discharge concentration of 33%. The overflow fineness of the vertical mill (-280 mesh ≥ 90%) is pumped into the first-stage atmospheric pressure slurry conditioning tank. Concentrated sulfuric acid, industrial water, and supernatant from a pressure thickener are pumped into the first-stage atmospheric pressure acid mixing tank to ensure a pH of 4.0~4.5. After mixing, the mixture is pumped into the first-stage atmospheric pressure slurry conditioning tank for slurry preparation. When the liquid level reaches 50% or higher, it can be fed into the first-stage atmospheric pressure leaching tank. The slurry is pumped into the first-stage atmospheric pressure leaching tank for atmospheric pressure leaching. The leaching tank temperature is 80℃, and 1000 Nm of compressed air is introduced. 3The leaching process is carried out at a rate of / h·stage, with a leaching time of 8 hours. The resulting solution has a pH ≥ 5.0. After leaching, the solution is concentrated and separated using an atmospheric pressure thickener to obtain a supernatant and a underflow. The underflow is pumped into a second-stage atmospheric pressure slurry conditioning tank, and the supernatant is filtered through a filter press to obtain the product, a nickel sulfate solution. Its specific components are: nickel 113.58 g / L; copper 0.0028 g / L; iron 0.0022 g / L; cobalt 1.47 g / L; lead 0.00038 g / L; zinc 0.0031 g / L; arsenic 0.00027 g / L; pH value 5.6. Step 2: Pump the supernatant from the CCD primary washing thickener, concentrated sulfuric acid, and industrial water / wastewater into the secondary atmospheric pressure acid mixing tank to prepare the solution, ensuring a pH of 0.5~1.0. After mixing, pump the solution into the secondary atmospheric pressure slurry preparation tank and mix it with the underflow from the primary atmospheric pressure leaching thickener for slurry preparation. When the liquid level reaches 50% or higher, feed material into the secondary atmospheric pressure leaching tank for secondary atmospheric pressure leaching. The leaching tank temperature is 80℃, and 950 Nm of compressed air is introduced. 3 / h·stage, leaching time is 8h, pH of the leaching solution after the second stage is 1.0~2.0; Step 3: The second-stage atmospheric pressure leaching slurry is pumped into the pressure leaching reactor, and oxygen is introduced to carry out the pressure leaching reaction. The oxygen flow rate during pressure leaching is 1200 Nm³. 3 The pressure leaching time was 6 hours, the pressure was 1.3 MPa, the temperature was 175℃, and the pH was 2.0. After cooling and depressurization in the flash evaporator, the product was sent to a thickener for concentration and separation to obtain supernatant and underflow. The supernatant was pumped into a first-stage atmospheric pressure acid mixing tank, and the underflow was pumped into a CCD primary washing thickener. Step 4: The supernatant from the CCD primary washing and thickening machine is used to slurry the first-stage atmospheric pressure filter residue or to supply the second-stage atmospheric pressure acid mixing tank. The underflow from the primary machine is pumped into the CCD secondary washing and thickening machine. The supernatant from the secondary machine is pumped into the CCD primary washing and thickening machine. The underflow is then pumped into the CCD tertiary washing and thickening machine. Industrial water is added to the tertiary thickening machine to wash the leaching residue. The supernatant from the tertiary thickening machine is pumped into the secondary washing and thickening machine. The underflow from the CCD tertiary thickening machine is filtered to obtain the leaching tailings. Its specific composition is: nickel 3.04%, cobalt 0.028%, iron 51.63%, and copper 1.23%.

[0015] Example 3 A method for efficiently preparing nickel sulfate solution using high-nickel matte includes the following steps: Step 1: The high-nickel matte bale is hoisted to the automatic feeding system. After breaking the bale, the material is conveyed to the ball mill via belt and ground with fresh water. The ball mill discharge concentration is 73%. The ball mill slurry is then ground in a vertical mill, with a discharge concentration of 36%. The overflow fineness of the vertical mill (-280 mesh ≥ 90%) is pumped into the first-stage atmospheric pressure slurry conditioning tank. Concentrated sulfuric acid, industrial water, and supernatant from a pressure thickener are pumped into the first-stage atmospheric pressure acid mixing tank to ensure a pH of 4.0~4.5. After mixing, the mixture is pumped into the first-stage atmospheric pressure slurry conditioning tank for slurry preparation. When the liquid level reaches 50% or higher, it can be fed into the first-stage atmospheric pressure leaching tank. The slurry is pumped into the first-stage atmospheric pressure leaching tank for atmospheric pressure leaching. The leaching tank temperature is 80℃, and 1000 Nm of compressed air is introduced. 3 The leaching process is carried out at a rate of / h·stage, with a leaching time of 8 hours. The resulting solution has a pH ≥ 5.0. After leaching, the solution is concentrated and separated using an atmospheric pressure thickener to obtain a supernatant and underflow. The underflow is pumped into a second-stage atmospheric pressure slurry conditioning tank, and the supernatant is filtered through a filter press to obtain the product, nickel sulfate solution. Its specific components are: nickel 117.41 g / L; copper 0.0038 g / L; iron 0.0022 g / L; cobalt 1.45 g / L; lead 0.00032 g / L; zinc 0.0030 g / L; arsenic 0.00031 g / L; pH value 5.5. Step 2: Pump the supernatant from the CCD primary washing thickener, concentrated sulfuric acid, and industrial water / wastewater into the secondary atmospheric pressure acid mixing tank to prepare the solution, ensuring a pH of 0.5~1.0. After mixing, pump the solution into the secondary atmospheric pressure slurry preparation tank and mix it with the underflow from the primary atmospheric pressure leaching thickener for slurry preparation. When the liquid level reaches 50% or higher, feed material into the secondary atmospheric pressure leaching tank for secondary atmospheric pressure leaching. The leaching tank temperature is 80℃, and compressed air at 1150 Nm³ is introduced. 3 / h·stage, leaching time is 8h, pH of the leaching solution after the second stage is 1.0~2.0; Step 3: The second-stage atmospheric pressure leaching slurry is pumped into the pressure leaching reactor, and oxygen is introduced to carry out the pressure leaching reaction. The oxygen flow rate during pressure leaching is 1300 Nm³. 3 The leaching process was carried out at a pressure of 1.5 MPa, a temperature of 175°C, and a pH of 2.0 for 6 hours per hour. After cooling and depressurization in a flash evaporator, the product was concentrated and separated in a thickener to obtain supernatant and underflow. The supernatant was pumped into a first-stage atmospheric pressure acid mixing tank, and the underflow was pumped into a CCD primary washing thickener. Step 4: The supernatant from the CCD primary washing and thickening machine is used to slurry the first-stage atmospheric pressure filter residue or to supply the second-stage atmospheric pressure acid mixing tank. The underflow from the primary machine is pumped into the CCD secondary washing and thickening machine. The supernatant from the secondary machine is pumped into the CCD primary washing and thickening machine. The underflow is then pumped into the CCD tertiary washing and thickening machine. Industrial water is added to the tertiary thickening machine to wash the leaching residue. The supernatant from the tertiary thickening machine is pumped into the secondary washing and thickening machine. The underflow from the CCD tertiary thickening machine is filtered to obtain the leaching tailings. Its specific composition is: nickel 2.85%, cobalt 0.021%, iron 55.34%, and copper 1.43%.

[0016] Comparative Example 1 The specific operation of this comparative example is the same as that of the embodiment, except that the amount of compressed air introduced in the first stage of atmospheric pressure leaching and the second stage of atmospheric pressure leaching is lower, and the amount of oxygen introduced and the reaction temperature are lower in the pressurized leaching.

[0017] A method for preparing nickel sulfate solution includes the following steps: Step 1: The high-nickel matte bale is hoisted to the automatic feeding system. After breaking the bale, the material is conveyed to the ball mill via belt and ground with fresh water. The ball mill discharge concentration is 75%. The ball mill slurry is then ground in a vertical mill, with a discharge concentration of 33%. The overflow fineness of the vertical mill (-280 mesh ≥ 90%) is pumped into the first-stage atmospheric pressure slurry conditioning tank. Concentrated sulfuric acid, industrial water, and supernatant from a pressure thickener are pumped into the first-stage atmospheric pressure acid mixing tank to ensure a pH of 4.0~4.5. After mixing, the mixture is pumped into the first-stage atmospheric pressure slurry conditioning tank for slurry preparation. When the liquid level reaches 50% or higher, it can be fed into the first-stage atmospheric pressure leaching tank. The slurry is pumped into the first-stage atmospheric pressure leaching tank for atmospheric pressure leaching. The leaching tank temperature is 80℃, and 700Nm of compressed air is introduced. 3 The leaching process is carried out at a rate of 8 hours per stage. The resulting solution has a pH ≥ 5.0. After leaching, the solution is concentrated and separated using an atmospheric pressure thickener to obtain a supernatant and a underflow. The underflow is pumped into a second-stage atmospheric pressure slurry conditioning tank, and the supernatant is filtered through a filter press to obtain the product, a nickel sulfate solution. Its specific components are: nickel 93.2 g / L; copper 0.032 g / L; iron 0.24 g / L; cobalt 1.06 g / L; lead 0.0043 g / L; zinc 0.0031 g / L; arsenic 0.00033 g / L; pH 5.0. Step 2: Pump the supernatant from the CCD primary washing thickener, concentrated sulfuric acid, and industrial water / wastewater into the secondary atmospheric pressure acid mixing tank to prepare the solution, ensuring a pH of 0.5~1.0. After mixing, pump the solution into the secondary atmospheric pressure slurry preparation tank and mix it with the underflow from the primary atmospheric pressure leaching thickener for slurrying. When the liquid level reaches 50% or higher, feed material into the secondary atmospheric pressure leaching tank for secondary atmospheric pressure leaching. The leaching tank temperature is 80℃, and 700Nm of compressed air is introduced. 3 / h·stage, leaching time is 8h, pH of the leaching solution after the second stage is 1.0~2.0; Step 3: The second-stage atmospheric pressure leaching slurry is pumped into the pressure leaching reactor, and oxygen is introduced to carry out the pressure leaching reaction. The oxygen flow rate during pressure leaching is 800 Nm³. 3 The leaching process was carried out at a pressure of 0.8 MPa, a temperature of 155°C, and a pH of 2.0 for 6 hours per unit. After cooling and depressurization in a flash evaporator, the product was concentrated and separated in a thickener to obtain supernatant and underflow. The supernatant was pumped into a first-stage atmospheric pressure acid mixing tank, and the underflow was pumped into a CCD primary washing thickener. Step 4: The supernatant from the CCD primary washing and thickening machine is used to slurry the first-stage atmospheric pressure filter residue or to supply the second-stage atmospheric pressure acid mixing tank. The underflow from the primary machine is pumped into the CCD secondary washing and thickening machine. The supernatant from the secondary machine is pumped into the CCD primary washing and thickening machine. The underflow is then pumped into the CCD tertiary washing and thickening machine. Industrial water is added to the tertiary thickening machine to wash the leaching residue. The supernatant from the tertiary thickening machine is pumped into the secondary washing and thickening machine. The underflow from the CCD tertiary thickening machine is filtered to obtain the leaching tailings. Its specific composition is: nickel 11.86%, cobalt 0.16%, iron 33.65%, and copper 0.98%.

[0018] The comparative examples show that under low temperature and low pressure conditions, the nickel content in the leachate is less than 100 g / L, the iron content is greater than 0.2 g / L, and the nickel content in the leaching tailings is greater than 10%. High-nickel matte cannot be fully leached, and the copper and iron cannot be opened up, which has a significant impact on product quality.

[0019] The above are merely preferred embodiments of the present invention. It should be noted that, for those skilled in the art, other equivalent modifications and improvements can be made based on the technical teachings provided by the present invention, and these should also be considered within the scope of protection of the present invention.

Claims

1. A method for efficiently preparing nickel sulfate solution using high-nickel matte, characterized in that, The main components of high-nickel matte are Ni: 70~75%, Cu: 0.1~0.5%, Co: 0.7~0.85%, Fe: 2.5~5.0%, and S: 10~15%, and the process includes the following steps: Step 1, Grinding: The high-nickel matte material is ground using a ball mill and then slurried with water to obtain a slurry; Step 2, First-stage atmospheric pressure leaching: The supernatant from the pressure thickener is pumped into the first-stage acid mixing tank, mixed with the grinding slurry, and then subjected to first-stage atmospheric pressure leaching. Steam and compressed air are introduced during the leaching process. After the leaching reaction is completed, solid-liquid separation is performed through the atmospheric pressure thickener. The supernatant is filtered to obtain a sulfuric acid solution, the main components of which are Ni: 110~120g / L, Co: 1.35~1.5g / L, Fe≤0.01g / L, S:≤0.02 g / L, and pH value 5.5~6.

0. The filter residue is washed with CCD first-stage washing and thickener supernatant and then pumped into the second-stage slurry conditioning tank. Step 3, Two-stage atmospheric pressure leaching: The underflow from the first-stage atmospheric pressure leaching thickener separation enters the second-stage slurry preparation tank, and is mixed with concentrated sulfuric acid, wastewater / industrial water and CCD primary washing thickener supernatant for slurry preparation. After slurry preparation, it is pumped into the second-stage atmospheric pressure leaching tank for the second-stage atmospheric pressure reaction. Steam and compressed air are introduced. After the reaction is completed, it is pumped into a pressure vessel for pressurized leaching reaction. To prevent the generation of hydrogen sulfide gas, copper sulfate needs to be added to the second-stage slurry preparation tank. Step 4, Pressure Leaching: The second-stage atmospheric pressure leachate is pumped into a pressure vessel, and oxygen is introduced to carry out the pressure leaching reaction. After the reaction, the slurry is cooled and depressurized and then thickened. The supernatant is used for the first-stage atmospheric pressure leaching solution preparation, and the underflow is pumped to a CCD washing thickener for washing. Step 5, CCD washing: After the pressurized leaching underflow undergoes three stages of washing, the washing liquid is used for the second stage of atmospheric leaching slurry preparation or the first stage of atmospheric leaching supernatant hydraulic filter residue slurrying. The underflow is then filtered to obtain the leaching tailings for discharge.

2. The method for efficiently preparing nickel sulfate solution using high-nickel matte according to claim 1, characterized in that, In step 1, the high-nickel matte is first ground using a ball mill to achieve a grinding fineness of -280 mesh > 75% and a discharge concentration of 70-80%. Then, the ball mill slurry is ground using a vertical mill to achieve a grinding fineness of -280 mesh > 90% and a discharge concentration of 30-40%.

3. The method for efficiently preparing nickel sulfate solution using high-nickel matte according to claim 1, characterized in that, In step 2, the pH of the slurry after preparation is 4.0~4.

5. The atmospheric pressure leaching process consists of seven leaching tanks (Φ4800×6500mm) connected in series. The leaching time is 8~10 hours, the temperature is 75~85℃, and the compressed air flow rate is 800~1200 Nm³. 3 / h.stage, reaction endpoint pH≥5.

0.

4. The method for efficiently preparing nickel sulfate solution using high-nickel matte according to claim 1, characterized in that, In step 3, the pH of the prepared slurry is 0.5~1.

0. The two-stage atmospheric pressure leaching process consists of seven leaching tanks with dimensions of Φ4800×6500mm connected in series. The leaching time is 8~10 hours, the temperature is 75~85℃, and the compressed air flow rate is 800~1200Nm. 3 / h. stage, reaction endpoint pH 1.0~2.

0.

5. The method for efficiently preparing nickel sulfate solution using high-nickel matte according to claim 1, characterized in that, In step 4, the pressure vessel has dimensions of Φ3900×21000 mm, and the oxygen flow rate during the pressure leaching process is 1000~1650 Nm³. 3 / h.platform, the pressure leaching time is 5~6h, the pressure is 0.8~1.6MPa, the temperature is 170~180℃, and the pressure leaching liquid level is 50~80%.

6. The method for efficiently preparing nickel sulfate solution using high-nickel matte according to claim 1, characterized in that, In step 5, industrial water is added to the CCD three-stage washing and thickening machine, the supernatant of the CCD three-stage washing and thickening machine is added to the CCD two-stage washing and thickening machine, and the supernatant of the CCD two-stage washing and thickening machine is added to the CCD one-stage washing and thickening machine. The supernatant of the CCD one-stage thickening machine is used to slurry the supernatant hydraulic filter residue of the first stage atmospheric pressure leaching or to supply the acid tank for the second stage atmospheric pressure leaching.

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