A method for recovering valuable metals from nickel matte during copper sulfate cyclic leaching.

Abstract

This invention discloses a method for recovering valuable metals from nickel matte in a copper sulfate cyclic leaching process. The main components of nickel matte are Ni: 25-35%, Cu: 16-22%, Fe: 16-20%, Co: 0.34-0.70%, and S: 18-24%. This method employs a sulfuric acid-copper sulfate leaching process, incorporating atmospheric pressure leaching, pressure displacement, pressure leaching, pressure iron removal, and evaporation crystallization. By controlling the leaching of copper and the concentrations of copper and acid in the solution at different process stages, the method achieves the leaching of nickel and iron. This method can separate the main metals in nickel matte, achieving the separation and enrichment of valuable metals and the comprehensive recovery and utilization of impurity metals. Ultimately, nickel and cobalt are separated in the form of crude nickel-cobalt sulfate crystals, which can be integrated into the production process of nickel-cobalt sulfate products; copper is separated in the form of copper slag containing precious metals, which can be integrated into copper smelting and precious metal recovery processes; and iron is separated in the form of ferric oxide, which can be integrated into the iron concentrate production process, realizing the resource utilization of iron.

Description

Technical Field

[0001] This invention belongs to the field of nickel pyrometallurgical technology, specifically a method for recovering valuable metals from nickel matte during copper sulfate cyclic leaching. Background Technology

[0002] In the smelting of nickel sulfide ore, nickel sulfide concentrate is smelted in a flash furnace (or top-blown furnace) to produce low-grade nickel matte. This low-grade nickel matte is then smelted in a converter to produce high-grade nickel matte. The main purpose of this process is to remove iron. During the converter smelting process, the iron content in the low-grade nickel matte is required to be reduced to less than 4%. However, the smelting process results in significant losses of cobalt and other metals, especially cobalt, with a loss rate as high as 50%. Furthermore, the resulting converter slag needs to be depleted in an electric depletion furnace. This repeated smelting process leads to repeated material recycling, repeated energy consumption, and severe environmental pollution. Research indicates that to improve the recovery rate of metals such as cobalt and reduce repeated smelting and environmental pollution, a hydrometallurgical process can be used to directly process low-grade nickel matte, replacing the traditional pyrometallurgical smelting process.

[0003] Pyrometallurgical smelting produces low-grade nickel matte with an iron content of 27-56%. The cost of wet processing for low-grade nickel matte is related to the iron content of the raw material; generally, as the iron content increases, the cost and complexity of wet processing also increase. Practice has shown that during the smelting of low-grade nickel matte to high-grade nickel matte, when the iron content in the nickel matte is 16-20%, the cobalt loss rate is relatively low. Based on this characteristic, the iron content in low-grade nickel matte can be reduced to 16-20%, resulting in nickel matte termed medium-grade nickel matte. This ensures that most of the iron is removed during pyrometallurgical smelting while maintaining a high cobalt recovery rate. Therefore, using a wet process for medium-grade nickel matte can correspondingly reduce costs and process complexity. Summary of the Invention

[0004] Based on the above, the present invention provides a simple and low-cost method for recovering valuable metals from nickel matte in the cyclic leaching of copper sulfate. By utilizing the cyclic leaching of copper in the raw materials, the separation and enrichment of valuable metals such as nickel and copper are achieved, and the sulfuric acid produced after iron removal is recycled, realizing a process with no wastewater and no waste residue discharge.

[0005] To achieve its purpose, the present invention adopts the following technical solution:

[0006] A method for recovering valuable metals from nickel matte during copper sulfate cyclic leaching includes the following steps:

[0007] a) Atmospheric pressure leaching: The above-mentioned nickel matte is slurried with water and added to an atmospheric pressure closed leaching reactor. Part of the crystallization mother liquor produced in step e) is also added to the atmospheric pressure closed reactor. The liquid-solid volume-to-mass ratio is controlled at 4:1 to 6:1. Atmospheric pressure leaching is carried out, and the leaching temperature is controlled at 70 to 90°C and the leaching endpoint pH is controlled at 1.5 to 3.0.

[0008] b) Pressure displacement: After the atmospheric pressure leaching reaction is completed, the reaction slurry and the copper sulfate solution obtained in step c) are added to the pressure reactor, and the temperature is raised to carry out pressure displacement leaching. The leaching temperature is controlled at 150~200℃ and the time is 2~6h. After the reaction is completed, the solid and liquid are separated to obtain the pressure displacement liquid and the displacement residue.

[0009] c) Pressure leaching: The replacement residue obtained in step b) is slurried with the evaporation crystallization condensate obtained in step e) and added to a pressure reactor. At the same time, part of the crystallization mother liquor produced in step e) is also added to the pressure reactor. The liquid-solid volume-to-mass ratio is controlled at 4:1 to 6:1. The temperature is raised and oxygen is introduced for pressure leaching. The leaching temperature is controlled at 150 to 180°C, the time is 1 to 3 hours, and the oxygen partial pressure is 0.1 to 0.3 MPa. After the reaction is completed, the solid and liquid are separated to obtain copper sulfate solution and copper slag.

[0010] d) Pressure removal of iron: The displacement liquid obtained in step b) is added to a pressure reactor. After the temperature reaches the reaction requirement, oxygen is introduced to remove iron under pressure. The iron removal temperature is controlled at 180~220℃, the time is 0.5~2h, and the oxygen partial pressure is 0.1~0.3MPa. After the reaction is completed, the solid and liquid are separated to obtain the iron-removed liquid and iron slag.

[0011] e) Evaporation and crystallization: The iron-removed liquid obtained in step d) is evaporated and crystallized to obtain crude nickel-cobalt sulfate crystals and crystallization mother liquor. Part of the crystallization mother liquor is returned to the atmospheric pressure leaching process, and the other part is returned to the pressure leaching process.

[0012] This invention achieves water recycling throughout the entire process. The leachate (copper sulfate solution) obtained from the pressure leaching process is returned to the pressure displacement process, and the mother liquor obtained from the evaporation crystallization process is returned to the pressure leaching and atmospheric pressure leaching processes, achieving volume balance throughout the process. At the start-up of the entire process, freshly prepared copper sulfate solution can be added to the pressure displacement process to initiate the reaction. Water can be added during the atmospheric and pressure leaching processes to replace the mother liquor returned during normal production to start the entire process. After the entire process is started, the pressure leaching solution (copper sulfate solution) is returned to the pressure displacement process, and the mother liquor is returned to the atmospheric and pressure leaching processes, achieving volume balance throughout the process.

[0013] As a preferred embodiment of the technical solution of the present invention, the medium-grade nickel matte is derived from low-iron nickel matte produced by pyrometallurgical smelting of nickel sulfide ore and then smelted in a converter. Its main components, by weight percentage, are: Ni: 25-35%, Cu: 16-22%, Fe: 16-20%, Co: 0.34-0.70%, and S: 18-24%.

[0014] Furthermore, the atmospheric pressure leaching time is 2-5 hours.

[0015] The beneficial effects of this invention are as follows:

[0016] 1. This invention proposes a method for copper sulfate cyclic leaching of nickel matte, an intermediate material produced by pyrometallurgical smelting of nickel sulfide ore. By utilizing the sulfuric acid-copper sulfate leaching process, valuable metals such as nickel and copper can be separated and enriched, and iron can be recycled and utilized.

[0017] 2. The method of the present invention solves the problem of sulfuric acid imbalance in the whole process caused by different iron and sulfur contents in the raw materials through the atmospheric pressure leaching process, and effectively controls the acid balance in the whole process.

[0018] 3. The method of the present invention achieves the leaching of iron, nickel and cobalt metals from medium nickel matte raw materials using copper ions through a pressure displacement-pressure leaching process, thereby reducing sulfuric acid consumption in the entire process.

[0019] 4. The method of this invention, by controlling the leaching of copper in different process stages and the concentrations of copper and sulfuric acid in the solution, can achieve the leaching of nickel and iron, thus achieving the separation and enrichment of valuable metals and the resource recovery and utilization of impurity elements. The entire process achieves the recycling of sulfuric acid produced during iron removal, which effectively reduces the consumption of acid and alkali reagents compared to traditional processes, and the entire process produces no wastewater or waste residue discharge.

[0020] 5. The method of the present invention can convert nickel, copper, cobalt and precious metals into crude nickel cobalt sulfate crystals and copper slag enriched with precious metals; iron is converted into iron slag mainly in the form of ferric oxide, which can be used as raw material for producing iron concentrate, realizing the resource recovery and utilization of iron. Attached Figure Description

[0021] Figure 1 This is a process flow diagram of the method for recovering valuable metals from nickel matte in the cyclic leaching of copper sulfate according to the present invention. Detailed Implementation

[0022] The process of the present invention will be described in detail below with reference to specific embodiments.

[0023] Example 1

[0024] The mass percentages of the main elements in this embodiment of nickel matte are shown in Table 1.

[0025] Table 1. Main element content (wt%) of nickel matte in Example 1

[0026]

[0027] Specific implementation process:

[0028] 1) After the nickel matte in Table 1 is slurried with water, it is added to a closed leaching reactor under normal pressure. Part of the crystallization mother liquor produced in the evaporation crystallization process is also added to the closed leaching reactor under normal pressure. The liquid-solid volume-to-mass ratio is controlled at 5:1. Leaching is carried out under normal pressure, with the leaching temperature controlled at 85℃, the time at 2.5h, and the pH at the leaching endpoint at 1.68.

[0029] 2) The atmospheric pressure reaction slurry and the pressure-leached copper sulfate solution were fed into a pressure reactor for pressure displacement leaching, controlling the leaching temperature at 150℃ and the time at 5 hours. After the reaction, solid-liquid separation was performed to obtain the pressure-displaced liquid and the displacement residue.

[0030] 3) The replacement residue was slurried using the condensate from evaporation and crystallization and then added to a pressure reactor. A certain amount of crystallization mother liquor (the remaining portion of the mother liquor required for atmospheric pressure leaching) was also added, controlling the liquid-to-solid volume-to-mass ratio at 5:1. The reactor was heated and oxygen was introduced for pressurized leaching, controlling the leaching temperature at 180℃, the time at 2 hours, and the oxygen partial pressure at 0.1 MPa. After the reaction, solid-liquid separation yielded copper sulfate leachate and copper slag containing precious metals.

[0031] 4) Add the replaced liquid to a pressure reactor and perform pressurized iron removal at a controlled temperature of 190℃, a reaction time of 1 hour, and an oxygen partial pressure of 0.1 MPa. After the reaction, separate the solid and liquid to obtain the iron-removed liquid and iron slag.

[0032] 5) After iron removal, the liquid is evaporated and crystallized to obtain crude nickel-cobalt sulfate crystals and crystallization mother liquor. Part of the crystallization mother liquor is returned to the atmospheric pressure leaching process, and the other part is returned to the pressure leaching process.

[0033] The main components of the main byproducts, crude nickel-cobalt sulfate crystals, copper slag, and iron slag, are shown in Table 2.

[0034] Table 2. Main product composition (%) of Example 1

[0035]

[0036] Example 2

[0037] The mass percentages of the main elements in this embodiment of nickel matte are shown in Table 3.

[0038] Table 3. Main element content (%) of nickel matte in Example 2

[0039]

[0040] Specific implementation process:

[0041] 1) After adding water to the nickel matte in Table 3 and slurrying it, add it to a closed leaching reactor under normal pressure. Also add part of the crystallization mother liquor produced in the evaporation crystallization process to the closed leaching reactor under normal pressure. Control the liquid-solid volume-to-mass ratio to be 4:1 and carry out leaching under normal pressure. Control the leaching temperature to be 90℃, the time to be 2h, and the pH of the leaching endpoint to be 1.95.

[0042] 2) The atmospheric pressure reaction slurry and the pressure-leached copper sulfate solution were fed into a pressure reactor for pressure displacement leaching, controlling the leaching temperature at 180℃ and the time at 3 hours. After the reaction, solid-liquid separation was performed to obtain the pressure-displaced liquid and the displacement residue.

[0043] 3) The replacement residue was slurried using evaporation crystallization condensate and then added to a pressure reactor, along with a certain amount of crystallization mother liquor (the remaining portion of the mother liquor required for atmospheric pressure leaching). The liquid-to-solid volume-to-mass ratio was controlled at 4:1. The reactor was heated and oxygen was introduced for pressurized leaching, with the leaching temperature controlled at 150℃, the time at 3 hours, and the oxygen partial pressure at 0.1 MPa. After the reaction, solid-liquid separation yielded copper sulfate leachate and copper slag containing precious metals.

[0044] 4) Add the replaced liquid to a pressure reactor and perform pressurized iron removal at a controlled temperature of 180℃, a time of 0.5 h, and an oxygen partial pressure of 0.3 MPa. After the reaction, separate the solid and liquid to obtain the iron-removed liquid and iron slag.

[0045] 5) After iron removal, the liquid is evaporated and crystallized to obtain crude nickel-cobalt sulfate crystals and crystallization mother liquor. Part of the crystallization mother liquor is returned to the atmospheric pressure leaching process, and the other part is returned to the pressure leaching process.

[0046] The main components of the crude nickel-cobalt sulfate crystals, copper slag, and iron slag are shown in Table 4.

[0047] Table 4. Main product composition (%) of Example 2

[0048]

[0049] Example 3

[0050] The mass percentages of the main elements in this embodiment of nickel matte are shown in Table 5.

[0051] Table 5. Main element content (%) of nickel matte in Example 3

[0052]

[0053] Specific implementation process:

[0054] 1) After adding water to the nickel matte in Table 5 and slurrying it, add it to the atmospheric pressure closed leaching reactor. Also add part of the crystallization mother liquor from the evaporation crystallization process to the atmospheric pressure closed reactor. Control the liquid-solid volume-to-mass ratio to be 6:1 and carry out atmospheric pressure leaching. Control the leaching temperature to be 90℃, the time to be 3h, and the pH of the leaching endpoint to be 2.0.

[0055] 2) The atmospheric pressure reaction slurry and the pressure-leached copper sulfate solution were added to a pressure reactor for pressure displacement leaching, controlling the leaching temperature at 180℃ and the time at 3 hours. After the reaction, solid-liquid separation was performed to obtain the pressure-displaced liquid and the displacement residue.

[0056] 3) The replacement residue was slurried using evaporation crystallization condensate and then added to a pressure reactor, along with a certain amount of crystallization mother liquor (the remaining portion of the mother liquor required for atmospheric pressure leaching). The liquid-to-solid volume-to-mass ratio was controlled at 6:1. The reactor was heated and oxygen was introduced for pressurized leaching, with the leaching temperature controlled at 180℃, the time at 1.5 h, and the oxygen partial pressure at 0.3 MPa. After the reaction, solid-liquid separation yielded copper sulfate leachate and copper slag containing precious metals.

[0057] 4) Add the replaced liquid to a pressure reactor and perform iron removal under pressure at a controlled temperature of 200℃, a time of 1 hour, and an oxygen partial pressure of 0.2 MPa. After the reaction, separate the solid and liquid to obtain the iron-removed liquid and iron slag.

[0058] 5) After iron removal, the liquid is evaporated and crystallized to obtain crude nickel-cobalt sulfate crystals and crystallization mother liquor. Part of the crystallization mother liquor is returned to the atmospheric pressure leaching process, and the other part is returned to the pressure leaching process.

[0059] The main components of the main byproducts, crude nickel-cobalt sulfate crystals, copper slag, and iron slag, are shown in Table 6.

[0060] Table 6. Main Product Components (%) of Example 3

[0061]

[0062] Example 4

[0063] The mass percentages of the main elements in this embodiment of nickel matte are shown in Table 7.

[0064] Table 7. Main element content (%) of nickel matte in Example 4

[0065]

[0066] Specific implementation process:

[0067] 1) After adding water to the nickel matte in Table 7 and slurrying it, add it to the atmospheric pressure closed leaching reactor. Also add part of the crystallization mother liquor from the evaporation crystallization process to the atmospheric pressure closed reactor. Control the liquid-solid volume-to-mass ratio to be 4:1 and carry out atmospheric pressure leaching. Control the leaching temperature to be 85℃, the time to be 3h, and the pH of the leaching endpoint to be 3.0.

[0068] 2) The atmospheric pressure reaction slurry and the pressure-leached copper sulfate solution were added to a pressure reactor for pressure displacement leaching, controlling the leaching temperature at 160℃ and the time at 5 hours. After the reaction, solid-liquid separation was performed to obtain the pressure-displaced liquid and the displacement residue.

[0069] 3) The replacement residue was slurried using evaporation crystallization condensate, then added to a pressure reactor along with a certain amount of crystallization mother liquor (the remaining portion of the mother liquor required for atmospheric pressure leaching). The liquid-to-solid volume-to-mass ratio was controlled at 4:1. The reactor was heated and oxygen was introduced for pressurized leaching, with the leaching temperature controlled at 170℃, the time at 2 hours, and the oxygen partial pressure at 0.2 MPa. After the reaction, solid-liquid separation yielded a copper sulfate solution and copper slag containing precious metals.

[0070] 4) Add the replaced liquid to a pressure reactor and perform pressurized iron removal at a controlled temperature of 215℃, a time of 2 hours, and an oxygen partial pressure of 0.1 MPa. After the reaction, separate the solid and liquid to obtain the iron-removed liquid and iron slag.

[0071] 5) After iron removal, the liquid is evaporated and crystallized to obtain crude nickel-cobalt sulfate crystals and crystallization mother liquor. Part of the crystallization mother liquor is returned to the atmospheric pressure leaching process, and the other part is returned to the pressure leaching process.

[0072] The main components of the main byproducts, crude nickel-cobalt sulfate crystals, copper slag, and iron slag, are shown in Table 8.

[0073] Table 8. Main product components (%) of Example 4

[0074]

[0075] This invention provides a simple and low-cost all-wet process for processing nickel matte produced by pyrometallurgical smelting. It utilizes the cyclic leaching of copper in the raw materials to separate and enrich valuable metals such as nickel and copper, and recycles the sulfuric acid produced from iron removal, achieving zero wastewater and zero waste residue discharge throughout the entire process.

Claims

1. A method for recovering valuable metals from nickel matte during copper sulfate cyclic leaching, characterized in that, The medium-grade nickel matte is derived from low-iron nickel matte obtained by converter blowing from low-grade nickel matte produced in the pyrometallurgical smelting of nickel sulfide ore. Its main components, by weight percentage, are: Ni: 25-35%, Cu: 16-22%, Fe: 16-20%, Co: 0.34-0.70%, S: 18-24%. The method includes the following steps: a) Atmospheric pressure leaching: The above-mentioned nickel matte is slurried with water and added to an atmospheric pressure closed leaching reactor. Part of the crystallization mother liquor produced in step e) is also added to the atmospheric pressure closed reactor. The liquid-solid volume-to-mass ratio is controlled at 4:1 to 6:

1. Atmospheric pressure leaching is carried out, and the leaching temperature is controlled at 70 to 90°C and the leaching endpoint pH is controlled at 1.5 to 3.

0. b) Pressure displacement: After the atmospheric pressure leaching reaction is completed, the reaction slurry and the copper sulfate solution obtained in step c) are added to the pressure reactor, and the temperature is raised to carry out pressure displacement leaching. The leaching temperature is controlled at 150~200℃ and the time is 2~6h. After the reaction is completed, the solid and liquid are separated to obtain the pressure displacement liquid and the displacement residue. c) Pressure leaching: The replacement residue obtained in step b) is slurried with the evaporation crystallization condensate obtained in step e) and added to a pressure reactor. At the same time, part of the crystallization mother liquor produced in step e) is also added to the pressure reactor. The liquid-solid volume-to-mass ratio is controlled at 4:1 to 6:

1. The temperature is raised and oxygen is introduced for pressure leaching. The leaching temperature is controlled at 150 to 180°C, the time is 1 to 3 hours, and the oxygen partial pressure is 0.1 to 0.3 MPa. After the reaction is completed, the solid and liquid are separated to obtain copper sulfate solution and copper slag. d) Pressure removal of iron: The displacement liquid obtained in step b) is added to a pressure reactor. After the temperature reaches the reaction requirement, oxygen is introduced to remove iron under pressure. The iron removal temperature is controlled at 180~220℃, the time is 0.5~2h, and the oxygen partial pressure is 0.1~0.3MPa. After the reaction is completed, the solid and liquid are separated to obtain the iron-removed liquid and iron slag. e) Evaporation and crystallization: The iron-removed liquid obtained in step d) is evaporated and crystallized to obtain crude nickel-cobalt sulfate crystals and crystallization mother liquor. Part of the crystallization mother liquor is returned to the atmospheric pressure leaching process, and the other part is returned to the pressure leaching process.

2. The method for recovering valuable metals from nickel matte in copper sulfate cyclic leaching as described in claim 1, characterized in that, The atmospheric pressure leaching time is 2-5 hours.

Images