Method for extracting cobalt, nickel, copper and iron from sulfur-cobalt concentrate through chlorination

Abstract

The invention discloses a method for extracting cobalt, nickel, copper and iron from sulfur-cobalt concentrate through chlorination, and belongs to the technical field of non-ferrous metal hydrometallurgy. The method comprises the following steps: crushing the cobalt pyrite concentrate, and fully pre-oxidizing the crushed cobalt pyrite concentrate in an oxygen atmosphere to obtain a pre-oxidized mineral material; putting the pre-oxidized mineral aggregate and a chlorinating agent into a reactor, and introducing chlorination gas for full chlorination to obtain a gas-phase product and chlorination residues; the gas-phase product is introduced into a condensation system and sequentially passes through a condensation temperature interval, FeCl3 crystals are condensed and recycled at the temperature of 200-300 DEG C, CuCl2 crystals are condensed and recycled at the temperature of 500-600 DEG C, and NiCl2 crystals are condensed and recycled at the temperature of 700-850 DEG C; and the chlorination residues are leached with a 0.5-1 mol / L HCl solution, and the leachate is subjected to extraction-electrodeposition to obtain electrolytic cobalt. The method is short in process, low in energy consumption and high in metal recovery rate, and can effectively solve the problem that an existing extraction process of valuable metal resources in the cobalt-sulfur concentrate is long in process.

Description

Technical Field

[0001] This invention belongs to the field of non-ferrous metal hydrometallurgical technology and relates to a method for extracting cobalt, nickel, copper and iron from cobalt sulfide concentrate by chlorination. Background Technology

[0002] Cobalt sulfide concentrate is an important raw material for extracting valuable metals such as cobalt and copper, and is usually associated with elements such as iron, sulfur, and nickel. Traditional methods for processing cobalt sulfide concentrate mainly fall into two categories: pyrometallurgical processes (such as reverberatory furnace smelting, electric furnace smelting, and flash smelting) and hydrometallurgical processes (such as pressure acid leaching, atmospheric pressure acid leaching, and bioleaching). Traditional pyrometallurgical processes are lengthy, energy-intensive, and result in significant cobalt loss in the slag, as well as a heavy burden on sulfur dioxide flue gas treatment. Furthermore, iron and cobalt are difficult to separate effectively during the smelting stage. Hydrometallurgical processes, on the other hand, consume high levels of reagents and have low efficiency, especially when processing high-sulfur or sparingly soluble minerals. These processes often require high temperatures and pressures, resulting in large consumption of acids / oxidants and unsatisfactory leaching efficiency. While leaching the target metal, large amounts of impurities such as iron are also dissolved, complicating subsequent purification and separation steps and increasing reagent consumption and metal loss. Whether it's pyrometallurgical or hydrometallurgical processes, the core problem lies in the generally lengthy process flow (involving multiple stages such as roasting, smelting / leaching, purification, and separation), resulting in large infrastructure investments, high operating energy consumption, long metal recycling cycles, and persistently high overall recycling costs.

[0003] Therefore, there is an urgent need to develop a more efficient, green, and economical process for extracting valuable metal resources from cobalt sulfide concentrate. Summary of the Invention

[0004] The technical problem to be solved by this invention is the lengthy process of extracting valuable metal resources from existing sulfur-cobalt concentrate.

[0005] To achieve the above-mentioned objectives, the technical solution adopted in this application is as follows: A method for extracting cobalt, nickel, copper, and iron from cobalt sulfide concentrate by chlorination, specifically including the following steps: S1. After crushing the cobalt sulfide concentrate, place it in an oxygen atmosphere and pre-oxidize it fully at 300~500℃ to obtain pre-oxidized ore; S2. The pre-oxidized ore and chlorinating agent are placed in a reactor, chlorination gas is introduced, and chlorination is carried out at 600~800℃ to obtain gaseous products and chlorination residue; wherein, the chlorinating agent is at least one of CaCl2, NaCl, KCl, AlCl3 or MgCl2; the chlorination gas is Cl2, or a mixture of Cl2 and an inert gas; S3. The gaseous product is passed into the condensation system and sequentially through the condensation temperature range. FeCl3 crystals are recovered by condensation at 200~300℃, CuCl2 crystals are recovered by condensation at 500~600℃, and NiCl2 crystals are recovered by condensation at 700~850℃. S4. Leach the chlorinated residue with 0.5~3 mol / L HCl solution, and obtain electrolytic cobalt by extraction-electrodeposition of the leachate.

[0006] The main chemical components of the aforementioned cobalt sulfide concentrate are Co 1~4wt.%, Ni 0.5~2.5wt.%, Cu 0.5~4wt.%, Fe 15~40wt.%, and S 25~35wt.%.

[0007] In step S1 above, the cobalt sulfide concentrate is crushed to -200 mesh.

[0008] In step S1 above, the pre-oxidation time is 1~2 hours.

[0009] In step S2 above, the amount of chlorinating agent added is 10-15% of the mass of the ore.

[0010] In step S2 above, the flow rate of chlorine gas is 1~2 L / min; when the chlorine gas is a mixture of Cl2 and an inert gas, the volume fraction of chlorine in the mixture is 30~50%.

[0011] In step S2 above, the chlorination time is 1~3 hours.

[0012] In step S3 above, the temperature difference between two adjacent condensation stages of the condensation system is ≥150℃.

[0013] In step S1 above, 5-8% CaO by weight of the ore is added to the crushed cobalt-sulfur concentrate, and then pre-oxidation is carried out.

[0014] In step S3 above, the tail gas from the chlorination reaction is passed into a NaOH solution for absorption to generate a NaClO3 solution. The NaClO3 solution is then electrolyzed to regenerate chlorine gas for reuse in step S2.

[0015] In step S3 above, the FeCl3 crystal is directly used as a water treatment agent, and the CuCl2 crystal and NiCl2 crystal are respectively subjected to molten salt electrolysis to obtain metallic copper and metallic nickel.

[0016] The beneficial effects of this invention are: chlorination metallurgy exhibits unique advantages over traditional pyrometallurgical methods when processing complex polymetallic resources such as cobalt sulfide concentrate. This invention breaks down the sulfide structure through pre-oxidation, combined with directional chlorination using a composite chlorinating agent (solid chlorinating agent + gaseous chlorinating agent) at moderate temperatures, precisely converting iron, copper, and nickel into volatile chlorides, while retaining cobalt in the residue; then, by adjusting the condensation temperature range of the stepped condensation system, the stepwise crystallization separation of iron, copper, and nickel chlorides in the gas phase is achieved.

[0017] Compared with existing technologies, this invention fundamentally simplifies the multi-metal separation process, eliminating the need for high-temperature smelting and repeated acid-base leaching. It simultaneously recovers three valuable metals through a single chlorination volatilization and three-stage condensation. Cobalt in the chlorination residue can be purified by mild acid leaching and extraction-electrodeposition, without the need for complex slag treatment. The smelting temperature of this invention is significantly lower than that of traditional smelting, greatly reducing energy consumption. Furthermore, this invention significantly improves resource utilization by recovering chlorine through tail gas electrolysis for recycling and by utilizing high-value byproducts. Introducing CaO in the pre-oxidation stage fixes sulfur to generate CaSO4, suppressing sulfur pollution emissions and achieving green production. Attached Figure Description

[0018] Figure 1 This is a process flow diagram of the method of the present invention. Detailed Implementation

[0019] To make the technical problems, solutions, and beneficial effects of this application clearer, the following detailed description is provided in conjunction with the embodiments. Unless otherwise defined, all technical terms used herein have the same meaning as understood by one of ordinary skill in the art.

[0020] Chlorination metallurgy (encompassing chlorination roasting and chlorination leaching) has demonstrated unique advantages as a highly promising alternative technology for processing complex polymetallic ores. Its core principle involves using chlorine gas, hydrogen chloride, or solid chlorinating agents (such as NaCl, CaCl2, MgCl2) under relatively mild temperature conditions to selectively chlorinate the oxides / sulfides of target metals (such as Co, Cu, Ni) or associated metals in the mineral, generating metal chlorides with high volatility (such as FeCl3, AlCl3) or high water solubility (such as CoCl2, CuCl2, NiCl2). This significant difference in the physicochemical properties of chlorides provides a crucial technical approach for the efficient and selective separation and enrichment of target valuable metals while simultaneously removing impurities, potentially significantly simplifying the process, reducing energy consumption, and improving metal recovery rates and economic efficiency.

[0021] Based on the characteristics of chlorination metallurgy, and to address the problem of lengthy extraction processes for valuable metal resources from existing cobalt sulfide concentrates, this invention provides a method for extracting cobalt, nickel, copper, and iron from cobalt sulfide concentrates (main chemical components: Co 1~2wt.%, Ni 0.5~1wt.%, Cu 0.5~4wt.%, Fe 15~40wt.%, S 25~35wt.%) via chlorination. The method specifically includes the following steps: S1. After crushing the cobalt sulfide concentrate, place it in an oxygen atmosphere and pre-oxidize it fully at 300~500℃ to obtain pre-oxidized ore; S2. The pre-oxidized ore and chlorinating agent are placed in a reactor, chlorination gas is introduced, and chlorination is carried out at 600~800℃ to obtain gaseous products and chlorination residue; wherein, the chlorinating agent is at least one of CaCl2, NaCl, KCl, AlCl3 or MgCl2; the chlorination gas is Cl2, or a mixture of Cl2 and an inert gas; S3. The gaseous product is passed into the condensation system and sequentially through the condensation temperature range. FeCl3 crystals are recovered by condensation at 200~300℃, CuCl2 crystals are recovered by condensation at 500~600℃, and NiCl2 crystals are recovered by condensation at 700~850℃. S4. Leach the chlorinated residue with 0.5~3 mol / L HCl solution, and obtain electrolytic cobalt by extraction-electrodeposition of the leachate.

[0022] In one embodiment of the present invention, in step S1, the cobalt sulfide concentrate is crushed to -200 mesh. This increases the specific surface area of ​​the ore, allowing oxygen to fully contact and oxidize the sulfides.

[0023] In one embodiment of the present invention, in step S1, the pre-oxidation temperature is 300~500℃, and the time is 1~2h. This temperature range ensures effective oxidation of sulfides, generating metal oxides and SO2 / SO3. Too low a temperature results in incomplete oxidation; too high a temperature may cause sintering of the material or changes in the morphology of the target metal oxide, which is detrimental to subsequent chlorination. The purpose of the pre-oxidation time is to ensure sufficient oxidation is achieved at the set temperature. As a non-limiting example, the pre-oxidation temperature can be 300℃, 310℃, 320℃, 330℃, 340℃, 350℃, 360℃, 370℃, 380℃, 390℃, 400℃, 410℃, 420℃, 430℃, 440℃, 450℃, 460℃, 470℃, 480℃, 490℃, 500℃, or any combination of two of the above values; the pre-oxidation time can be 1h, 1.5h, 2h, or any combination of two of the above values.

[0024] In one embodiment of the present invention, in step S1, 5-8% CaO by weight of the crushed cobalt-sulfur concentrate is added, followed by pre-oxidation. The purpose is to convert the SO2 / SO3 generated during oxidation into stable CaSO4, which is then fixed in the slag, reducing sulfur oxide emissions. As a non-limiting example, the amount of CaO added can be 5%, 6%, 7%, 8% by weight of the ore, or within any two of these values.

[0025] In one embodiment of the present invention, in step S2, the chlorinating agent is at least one of CaCl2, NaCl, KCl, AlCl3, or MgCl2; the amount of chlorinating agent added is 10-15% of the ore mass. In this invention, the chlorinating agent has a dual function: firstly, it provides a supplementary chlorine source, decomposing at high temperatures or reacting with sulfides to release Cl2; secondly, it acts as a flux to lower the melting point and viscosity of the slag, promoting reaction kinetics and metal volatilization. The amount of chlorinating agent added directly affects the chlorination efficiency and metal volatilization rate. As a non-limiting example, the chlorinating agent can be CaCl2, NaCl, KCl, AlCl3, MgCl2, or a mixture of any two or more of the above substances in any proportion; the amount of chlorinating agent added can be 10%, 11%, 12%, 13%, 14%, 15% of the ore mass, or within any range of two of the above values.

[0026] In one embodiment of the present invention, in step S2, the chlorinating gas is Cl2, or a mixture of Cl2 and an inert gas. When the chlorinating gas is a mixture of Cl2 and an inert gas, the volume fraction of chlorine in the mixture is 30-50%; the flow rate of the chlorinating gas is 1-2 L / min. In the present invention, the chlorinating gas needs to provide sufficient chlorinating agent concentration and flow rate to ensure the reaction rate and the formation and volatilization of metal chlorides. If the flow rate is too low, the reaction is slow and volatilization is incomplete; if it is too high, it is uneconomical and places a heavy burden on tail gas treatment. As a non-limiting example, the flow rate of the chlorinating gas can be 1 L / min, 1.5 L / min, 2 L / min, or within any two of the above values.

[0027] In one embodiment of the present invention, in step S2, the chlorination temperature is 600~800℃, and the time is 1~3h. Chlorination temperature is a necessary condition for achieving efficient chlorination and volatilization of metal oxides (especially Fe, Cu, and Ni chlorides). Too low a temperature results in a slow chlorination rate and incomplete volatilization; too high a temperature may cause excessive volatilization of chlorides, making condensation control difficult or increasing energy consumption. As a non-limiting example, the chlorination temperature can be 600℃, 700℃, 800℃, or any combination of two of these values; the chlorination time can be 1h, 2h, 3h, or any combination of two of these values.

[0028] In one embodiment of the present invention, in step S3, the condensation temperature ranges of the condensation system are set sequentially to 200~300℃, 500~600℃, and 700~850℃. The condensation temperature ranges of the present invention are precisely set based on the differences in the saturated vapor pressures of the three chlorides: FeCl3, CuCl2, and NiCl2. In the 200~300℃ range, FeCl3 has the lowest vapor pressure and preferentially condenses and precipitates; then it enters the 500~600℃ range where CuCl2 condenses; finally, it enters the 700~850℃ range where NiCl2 condenses. As a non-limiting example, the condensation temperature of FeCl3 crystals can be 200℃, 250℃, 300℃, or any combination of two of these values; the condensation temperature of CuCl2 crystals can be 500℃, 550℃, 600℃, or any combination of two of these values; and the condensation temperature of NiCl2 crystals can be 700℃, 750℃, 800℃, 850℃, or any combination of two of these values.

[0029] In one embodiment of the present invention, in step S3, the temperature difference between two adjacent condensation zones of the condensation system is ≥150°C. A larger temperature difference can more effectively reduce the cross-condensation of different metal chloride vapors in the condensation zone, thereby improving separation efficiency and product purity.

[0030] In one embodiment of the present invention, in step S3, the chlorination reaction tail gas is passed into a NaOH solution for absorption to generate a NaClO3 solution. The NaClO3 solution is then electrolyzed to regenerate chlorine gas for reuse in step S2. The purpose is to treat toxic chlorine-containing tail gas and achieve the recycling of chlorine resources, reducing raw material consumption and environmental pressure, and improving both environmental friendliness and economic efficiency.

[0031] In one embodiment of the present invention, in step S3, the FeCl3 crystals are directly used as a water treatment agent, while the CuCl2 and NiCl2 crystals are subjected to molten salt electrolysis to obtain metallic copper and metallic nickel, respectively. Using FeCl3 crystals directly as a water treatment agent improves economic efficiency. Furthermore, FeCl3 can also be considered for the production of iron-based products or sold as a byproduct. Further processing of CuCl2 and NiCl2 crystals to obtain metal products increases product value. These chloride crystals can also be sold as chemical raw materials or used in other methods (such as aqueous solution electrolytic reduction) to produce metals.

[0032] The following specific embodiments will be provided to explain the solution of the present invention. Those skilled in the art will understand that the following embodiments are for illustrative purposes only and should not be considered as limiting the scope of the invention. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in the field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0033] Example 1: Cobalt sulfide concentrate (Co 1.2%, Ni 0.8%, Cu 0.5%, Fe 38%, S 32%) was crushed to 200 mesh. The concentrate was placed in a tubular furnace, and 6% (by weight) of calcium oxide was added. The reaction temperature was set to 300°C, and oxygen was introduced for roasting for 1 hour to obtain the concentrate. The concentrate and 12% (by weight) of CaCl2 were placed in a chlorination reactor, and Cl2 was introduced at 1.2 L / min. The reaction was carried out at 600°C for 1 hour. The gaseous products were fed into a condensation system and a tail gas absorption system. FeCl3, CuCl2, and NiCl2 crystals were recovered by condensation at temperatures of 200°C, 500°C, and 700°C, respectively. The residue after chlorination roasting was leached with a 0.5 mol / L HCl solution. The leaching solution was extracted with P507 and then acid-back-extracted before electrodeposition to obtain 99.8% pure electrolytic cobalt product.

[0034] The final recovery rates were 89% for cobalt, 90.3% for nickel, 90.5% for copper, and 85.7% for iron. The Cl2 reuse rate from the electrolytic regeneration of the absorbent was 78%.

[0035] Example 2: Cobalt sulfide concentrate (Co 1.2%, Ni 0.8%, Cu 0.5%, Fe 38%, S 32%) was crushed to 200 mesh. The concentrate was placed in a tubular furnace, and 7% (by weight) of calcium oxide was added. The reaction temperature was set at 350°C, and oxygen was introduced for roasting for 1.5 hours to obtain the concentrate. The concentrate and 10% (by weight) of CaCl2 were placed in a chlorination reactor, and Cl2 was introduced at a rate of 1.2 L / min. The reaction was carried out at 700°C for 2 hours. The gaseous products were fed into a condensation system and a tail gas absorption system, and FeCl3, CuCl2, and NiCl2 crystals were recovered by condensation at temperatures of 250°C, 550°C, and 750°C, respectively. The residue after chlorination roasting was leached with a 0.8 mol / L HCl solution. The leaching solution was extracted with P507 and then acid-back-extracted before electrodeposition to obtain 99.8% pure electrolytic cobalt product.

[0036] The final recovery rates were 92% for cobalt, 94.1% for nickel, 96.5% for copper, and 89.7% for iron. The Cl2 reuse rate from the electrolytic regeneration of the absorbent was 81%.

[0037] Example 3: Cobalt sulfide concentrate (Co 1.2%, Ni 0.8%, Cu 0.5%, Fe 38%, S 32%) was crushed to 200 mesh. The concentrate was placed in a tubular furnace, and 8% (by weight) of calcium oxide was added. The reaction temperature was set to 400°C, and oxygen was introduced for roasting for 2 hours. The pre-oxidized concentrate and 15% (by weight) of CaCl2 were placed in a chlorination reactor, and Cl2 was introduced at 1.2 L / min. The reaction was carried out at 800°C for 3 hours. The gaseous products were fed into a condensation system and a tail gas absorption system, and FeCl3, CuCl2, and NiCl2 crystals were recovered by condensation at temperatures of 300°C, 600°C, and 800°C, respectively. The residue after chlorination roasting was leached with a 1.0 mol / L HCl solution. The leaching solution was extracted with P507 and then acid-back-extracted before electrodeposition to obtain 99.8% pure electrolytic cobalt product.

[0038] The final recovery rates were 96% for cobalt, 98% for nickel, 98.5% for copper, and 93% for iron. The Cl2 reuse rate from the electrolytic regeneration of the absorbent was 83%.

[0039] Example 4: Cobalt sulfide concentrate (Co 1.8%, Ni 0.6%, Cu 3.2%, Fe 18%, S 28%) was crushed to 200 mesh. The concentrate was placed in a tubular furnace, and 6% (by weight) of calcium oxide was added. The reaction temperature was set to 450°C, and oxygen was introduced for roasting for 1.5 hours. The pre-oxidized concentrate and 12% (by weight) of CaCl2 were placed in a chlorination reactor, and 12 wt.% chlorinating agent (CaCl2:NaCl = 3:1) was added. A Cl2-N2 mixture (40% Cl2 by volume) was introduced, and the reaction was carried out at 750°C for 2.5 hours. The gaseous products of the reaction were fed into a condensation system and a tail gas absorption system. FeCl3, CuCl2, and NiCl2 crystals were recovered by condensation at temperatures of 280°C, 500°C, and 850°C, respectively. The residue after chlorination roasting was leached with 1.2 mol / L HCl solution. The leaching solution was then extracted with P204 and acid-back-extracted before electrodeposition to obtain 99.95% electrolytic cobalt product.

[0040] The final recovery rates were 98% for cobalt, 96% for nickel, 97% for copper, and 91% for iron. The Cl2 reuse rate from the electrolytic regeneration of the absorbent was 85%.

Claims

1. A method for extracting cobalt, nickel, copper, and iron from cobalt sulfide concentrate by chlorination, characterized in that, The steps include: S1. After crushing the cobalt sulfide concentrate, place it in an oxygen atmosphere and pre-oxidize it fully at 300~500℃ to obtain pre-oxidized ore; S2. The pre-oxidized ore and chlorinating agent are placed in a reactor, chlorination gas is introduced, and chlorination is carried out at 600~800℃ to obtain gaseous products and chlorination residue; wherein, the chlorinating agent is at least one of CaCl2, NaCl, KCl, AlCl3 or MgCl2; the chlorination gas is Cl2, or a mixture of Cl2 and an inert gas; S3. The gaseous product is passed into the condensation system and sequentially through the condensation temperature range. FeCl3 crystals are recovered by condensation at 200~300℃, CuCl2 crystals are recovered by condensation at 500~600℃, and NiCl2 crystals are recovered by condensation at 700~850℃. S4. Leach the chlorinated residue with 0.5~3 mol / L HCl solution, and obtain electrolytic cobalt by extraction-electrodeposition of the leachate.

2. The method for chlorinating cobalt, nickel, copper, and iron from cobalt sulfide concentrate according to claim 1, characterized in that: The main chemical components of the cobalt sulfide concentrate are Co 1~4wt.%, Ni 0.5~2.5wt.%, Cu 0.5~4wt.%, Fe 15~40wt.%, and S 25~35wt.%.

3. The method for chlorinating cobalt, nickel, copper, and iron from cobalt sulfide concentrate according to claim 1, characterized in that: In step S1, the cobalt sulfide concentrate is crushed to -200 mesh.

4. The method for chlorinating cobalt, nickel, copper, and iron from cobalt sulfide concentrate according to claim 1, characterized in that: In step S1, the pre-oxidation time is 1~2 hours.

5. The method for chlorinating cobalt, nickel, copper, and iron from cobalt sulfide concentrate according to claim 1, characterized in that: In step S2, the amount of chlorinating agent added is 10-15% of the mass of the ore.

6. The method for extracting cobalt, nickel, copper, and iron from cobalt sulfide concentrate by chlorination according to claim 1, characterized in that: In step S2, the flow rate of chlorine gas is 1~2 L / min; when the chlorine gas is a mixture of Cl2 and an inert gas, the volume fraction of chlorine in the mixture is 30~50%.

7. The method for chlorinating cobalt, nickel, copper, and iron from cobalt sulfide concentrate according to claim 1, characterized in that: In step S2, the chlorination time is 1~3 hours.

8. The method for chlorinating cobalt, nickel, copper, and iron from cobalt sulfide concentrate according to claim 1, characterized in that: In step S3, the temperature difference between two adjacent condensation stages of the condensation system is ≥150℃.

9. The method for chlorinating cobalt, nickel, copper, and iron from cobalt sulfide concentrate according to claim 1, characterized in that, At least one of the following conditions must be met: In step S1, 5-8% CaO by weight of the ore is added to the crushed cobalt-sulfur concentrate, and then pre-oxidation is carried out. In step S3, the tail gas from the chlorination reaction is passed into a NaOH solution for absorption to generate a NaClO3 solution. The NaClO3 solution is then electrolyzed to regenerate chlorine gas for reuse in step S2.

10. The method for chlorinating cobalt, nickel, copper, and iron from cobalt sulfide concentrate according to claim 1, characterized in that: In step S3, the FeCl3 crystal is used directly as a water treatment agent, and the CuCl2 crystal and NiCl2 crystal are subjected to molten salt electrolysis to obtain metallic copper and metallic nickel, respectively.

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