Oxygen leaching iron removal treatment method for nickel sulfide concentrate

Abstract

The invention relates to an oxygen leaching iron removal treatment method for nickel sulfide concentrate, which comprises the following steps: mixing the nickel sulfide concentrate to be treated with oxygen pressure leachate, reacting at 65-85 DEG C, and when the pH value of a reaction system is 1-2, carrying out solid-liquid separation to obtain neutralized slag and neutralized liquid; carrying out oxygen pressure leaching treatment on the neutralized slag, and carrying out solid-liquid separation to obtain oxygen pressure leaching liquid and oxygen pressure leaching slag; and after iron removal treatment is conducted on the neutralized liquid through a hematite method, solid-liquid separation is conducted, and iron-removed liquid and hematite slag are obtained. According to the method, the neutralization slag is leached by adding water and oxygen pressure, sulfuric acid does not need to be added, most sulfur in the mineral is oxidized to generate sulfuric acid under the high-temperature strong oxidation condition, and the leaching rates of nickel, copper and cobalt are all larger than 94%.

Description

Technical Field

[0001] This invention relates to an oxygen leaching method for removing iron from nickel sulfide concentrate, belonging to the field of hydrometallurgy. Background Technology

[0002] Nickel sulfide concentrate generally contains valuable metals such as copper and cobalt, with impurities mainly consisting of iron and gangue. Traditionally, pyrometallurgical processes are used. However, with increased mining activity, rich ore resources are decreasing while poor ore resources are increasing. For nickel sulfide concentrates with low copper and cobalt content, pyrometallurgical processes result in the slag carrying away significant amounts of nickel, copper, and cobalt, leading to the loss of valuable metals. Hydrometallurgical oxygen pressure leaching offers advantages in strengthening the metallurgical process. Under high temperature and pressure conditions, it can significantly reduce the nickel, copper, and cobalt content in the oxygen leaching slag, significantly improving the recovery rate of valuable metals. However, nickel sulfide concentrates generally have a high iron content, and during oxygen pressure leaching, a large amount of iron is also leached into the solution. Traditional neutralization to remove iron produces a large amount of neutralization slag, which carries away valuable metals, resulting in the loss of nickel, copper, and cobalt. Furthermore, the iron in the slag is not utilized as a resource.

[0003] The applicant's previous Chinese invention patent application CN202110489660.0 disclosed an oxygen pressure leaching method for nickel sulfide concentrate. The method involves finely grinding the nickel sulfide concentrate with water to obtain a slurry; then mixing the slurry with a second-stage oxygen pressure leaching solution, controlling the liquid-to-solid ratio at 2-3:1 and the initial acid concentration at 40-50 g / L, and performing a first-stage oxygen pressure leaching in a first high-pressure reactor, followed by solid-liquid separation to obtain a first-stage oxygen pressure leaching solution and a first-stage oxygen pressure leaching residue; then, transferring the first-stage oxygen pressure leaching solution to a second high-pressure reactor, adding sulfuric acid solution, controlling the liquid-to-solid ratio at 2-3:1 and the initial acid concentration at 90-100 g / L, introducing oxygen, and performing a second-stage oxygen pressure leaching, followed by solid-liquid separation to obtain a second-stage oxygen pressure leaching solution and a second-stage oxygen pressure leaching residue; finally, returning the obtained second-stage oxygen pressure leaching solution to the first-stage oxygen pressure leaching process. This invention employs a two-stage countercurrent oxygen pressure leaching process for nickel sulfide concentrate, using a high-temperature strong oxygen-step acid reduction-weak acid iron removal method. This achieves efficient leaching of nickel, copper, and cobalt while simultaneously reducing acid and removing iron. The first-stage oxygen pressure leaching solution contains approximately 3g / L of both acid and iron, allowing it to be directly sent to subsequent purification processes without the need for a neutralization and iron removal process, thus reducing metal loss carried away by the neutralization slag. However, the leaching slag and iron removal slag are not separated, meaning the iron in the raw material is not utilized as a resource. This technology still has room for optimization. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide an oxygen leaching method for removing iron from nickel sulfide concentrate.

[0005] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:

[0006] A method for removing iron from nickel sulfide concentrate by oxygen leaching includes the following steps:

[0007] S1. Mix the nickel sulfide concentrate to be treated with oxygen pressure leaching solution, react at 65-85℃ for 1-2 hours, then separate the solid and liquid to obtain neutralized slag and neutralized liquid.

[0008] S2. After oxygen pressure leaching treatment of the neutralized residue, solid-liquid separation is performed to obtain oxygen pressure leaching solution and oxygen pressure leaching residue.

[0009] After the neutralized liquid is treated with iron removal by the hematite method, solid-liquid separation is performed to obtain the iron-removed liquid and hematite slag.

[0010] Among them, the oxygen pressure leachate is returned to S1.

[0011] Furthermore, in S1, the reaction is carried out at 68-82°C, preferably at 70-80°C.

[0012] Optionally, in the nickel sulfide concentrate to be processed, nickel exists in the form of pyrite.

[0013] Optionally, in the nickel sulfide concentrate to be processed, copper exists in the form of chalcopyrite.

[0014] Optionally, in the nickel sulfide concentrate to be processed, cobalt exists in the form of cobalt sulfide.

[0015] Optionally, in the nickel sulfide concentrate to be processed, iron exists in the form of pyrrhotite and / or pyrrhotite.

[0016] Optionally, the nickel sulfide concentrate to be processed contains gangue, and optionally, the gangue includes serpentine (Mg6[Si4O3]2O3). 10 ](OH)8), Talc ((Mg6)[Si8]O 20 (OH)4), one or more of chlorite.

[0017] Further, in S1, the nickel sulfide concentrate to be processed has a Ni content ≥1wt%, a Cu content of 0-10wt%, a Co content of 0-10wt%, and an Fe content of 0.5-35wt%; preferably, the Ni content is 2-15wt%, the Cu content is 1-6wt%, the Co content is 0.05-5wt%, and the Fe content is 1-30wt%.

[0018] Further, in S1, the nickel sulfide concentrate to be treated is mixed with oxygen pressure leaching solution at a solid-liquid ratio of 1g:2-6mL.

[0019] Furthermore, in S1, the pH value of the neutralized solution is 1-2.

[0020] Further, in S2, after the neutralized residue is subjected to oxygen pressure leaching treatment, the temperature and pressure are reduced, and then solid-liquid separation is performed to obtain oxygen pressure leaching solution and oxygen pressure leaching residue.

[0021] Optionally, the oxygen pressure leaching residue can be washed and then stored or sold.

[0022] Further, in S2, after the neutralized liquid is treated by iron removal using the hematite method, it is cooled and depressurized, and then concentrated and separated to obtain the iron-removed liquid and hematite slag; preferably, the cooling and depressurization are carried out by a flash evaporation tank.

[0023] Further, in S2, the neutralized residue is first mixed with water and finely ground to obtain a finely ground slurry with a solid content of 60-70 wt%. Then, the slurry is adjusted to obtain a diluted slurry with a solid-liquid mass ratio of 1 g: 2-6 mL, and then oxygen pressure leaching is performed.

[0024] Among them, the proportion of mineral particles with a particle size of less than 20 μm in the solid phase of finely ground slurry is ≥90 wt%.

[0025] Preferably, the water is pure water or raffinate;

[0026] Preferably, the water used for slurry preparation is pure water or raffinate.

[0027] Thus, by neutralizing the slag and then finely grinding it, the volume of fine grinding can be effectively reduced, energy consumption can be saved, and processing efficiency can be improved. At the same time, fine grinding further crushes the slag, and the valuable ore body and residual gangue are liberated, which helps to further improve the effect of subsequent oxygen pressure leaching.

[0028] Furthermore, in S2, oxygen pressure leaching is performed without the addition of acid; preferably, oxygen with a concentration of 55 vol% or more is introduced during oxygen pressure leaching, more preferably 80-99 vol%.

[0029] Furthermore, in S2, during oxygen pressure leaching, the temperature is controlled at 180-190℃, the pressure at 1.5-1.6 MPa, and the time at 2.0-3.0 h.

[0030] Furthermore, in S2, the oxygen pressure leaching is either a single-stage oxygen pressure leaching or a multi-stage oxygen pressure leaching.

[0031] Furthermore, in S2, during the iron precipitation treatment, oxygen with a concentration ≥90 vol% (preferably 95-99 vol%) is introduced into the neutralized liquid, and the temperature is controlled at 165-200℃ (preferably 170-195℃), the pressure at 1.6-1.8 MPa (preferably 1.65-1.75 MPa), and the time is 2.5-4.0 h (preferably 3-3.5 h).

[0032] Furthermore, in S2, every 1m 3The oxygen flow rate into the neutralized solution is 3-4 Nm³. 3 Preferably, it is 3.2-3.8 Nm. 3 .

[0033] Furthermore, in S2, iron removal is performed through an iron removal system. The iron removal system includes a first pipeline, N reactors, a second pipeline, a third pipeline, a fourth pipeline, N ninth valves, tenth valves, twelfth valves, and a solid-liquid separation unit. The reactors include tanks with inlets, outlets, air inlets, and manholes. A stirring mechanism is provided inside the tanks. Each inlet is connected in parallel to the first pipeline, each outlet is connected in parallel to the third pipeline, and each air inlet is connected in parallel to the second pipeline.

[0034] A fourth valve and a seventh valve are provided between the first pipeline and the feed inlet. The feed inlet, the fourth valve, the seventh valve and the first pipeline are connected in sequence. The pipeline between the fourth valve and the seventh valve is connected to the third pipeline. A third valve is provided between the second pipeline and the air inlet. A fifth valve is provided between the third pipeline and the discharge port. One port of the ninth valve is connected to the pipeline between the fifth valve and the third pipeline, and the other port of the ninth valve is connected to the fourth pipeline.

[0035] An eleventh valve is provided on the third pipeline between the inlet and outlet of the same tank; an eighth valve is provided on the third pipeline between two adjacent tanks; preferably, an eighth valve is provided on the third pipeline between the outlet of the first tank and the inlet of the second tank in two adjacent tanks.

[0036] One port of the tenth valve is connected to one end of the third pipeline, one port of the twelfth valve is connected to the other end of the third pipeline, and the other port of the tenth valve and the other port of the twelfth valve are connected in parallel to the inlet end of the solid-liquid separation unit.

[0037] Wherein, N is an integer ≥2, preferably 4-6, and more preferably 5.

[0038] In this way, each reactor can serve as a backup for the others, allowing the neutralized liquid to flow through each reactor sequentially for iron precipitation. Specifically, when the nth (5≥n≥1) reactor needs cleaning, it is short-circuited through valve and pipeline control, turning the next reactor into the first reactor; after cleaning, it is turned on through valve and pipeline control, turning the reactor into the N-n+1th reactor.

[0039] When it is necessary to clean the iron slag in a reactor or to perform maintenance, the third, fourth, and fifth valves corresponding to that reactor can be closed to short-circuit the reactor, allowing the neutralized liquid to first flow through other reactors for iron removal. After the cleaning or maintenance of that reactor is completed, the opening and closing positions of the relevant valves can be adjusted to allow the solution to flow into that reactor for further treatment before being discharged. In this way, the iron removal system can be guaranteed to operate continuously and stably, improving processing efficiency.

[0040] Optionally, the reactor is a vertical reaction vessel.

[0041] Preferably, the neutralized liquid flows sequentially through the N reactors; when the iron content of the neutralized liquid entering the first reactor is >20 g / L, the iron removal efficiency is controlled at 16-24 kg·m³. -3 ·h -1 The temperature is 185-200℃, the residence time is 0.15-1h, and a solution with an iron content of <20g / L is obtained.

[0042] The iron removal efficiency of the subsequent N-1 reactors should be controlled at 5-7 kg·m³. -3 ·h -1 The total residence time in reactor N-1 is 1.5-3 hours, and the temperature is 165-180℃.

[0043] In this invention, iron removal efficiency refers to the amount of iron removed per cubic meter of reaction volume per hour (iron removal amount kg·reactor volume m). -3 ·Duration of stay h -1 (Unit: kg·m) -3 ·h -1 .

[0044] Preferably, more than 40 wt% of the iron in the neutralized liquid is converted into iron slag in the first reactor. In this case, the iron slag in the first reactor is relatively easy to form slag. The remaining iron enters the subsequent reactors and is converted into iron slag without forming slag. Therefore, when the first reactor needs to be cleaned, the subsequent N-1 reactors can still work normally. At this time, the first reactor can be short-circuited as described above, so that the neutralized liquid flows into the subsequent other reactors for treatment, thereby ensuring that the iron removal system can always be in operation.

[0045] Furthermore, during the iron removal process, the iron removal efficiency in the first reactor (at which point the solution typically contains more than 20 g / L of iron) is initially controlled to be 16-24 kg·m³. -3 ·h -1 The reaction temperature is 185-200℃, causing more than 40% of the iron in the solution to be converted into iron slag and partially deposited in the first reactor; then, the iron removal efficiency in subsequent reactors (at this point, the solution typically contains less than 20 g / L of iron) is controlled to be 5-7 kg·m³. -3 ·h-1 The reaction temperature is 165-180℃, which allows about 60% of the iron in the remaining solution to enter the subsequent reactor and be converted into iron slag, effectively reducing the amount of iron slag deposited in the reactor.

[0046] This invention mixes nickel sulfide concentrate with oxygen pressure leaching solution. On one hand, the gangue in the nickel sulfide concentrate can react with the sulfuric acid in the oxygen pressure leaching solution, reducing the acidity and revealing valuable ore bodies. On the other hand, the sulfides in the nickel sulfide concentrate can reduce the Fe content in the oxygen pressure leaching solution. 3+ Most of it is reduced to Fe 2+ This prepares the ground for subsequent iron removal from hematite. Subsequently, the hematite method can effectively remove iron from the neutralized solution, transforming the iron into hematite slag (Fe2O3). Furthermore, under oxygen pressure leaching conditions, most of the sulfur in the neutralized slag is oxidized to produce sulfuric acid, which then leaches nickel, copper, cobalt, and iron from the minerals into the solution.

[0047] Furthermore, the iron-removed liquid can be sent to subsequent purification-extraction-crystallization-electrowinning processes to produce nickel sulfate, cobalt sulfate, and electrowinning copper, respectively. The underflow is filtered by a centrifuge to produce hematite slag. In the extraction step, there is no need to remove iron again through an extraction process, which helps to shorten the process, reduce the amount of organic extraction reagents used, further save costs, and reduce the adverse effects of organic reagents on the product.

[0048] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0049] (1) In this invention, the neutralized residue can be leached by adding water and oxygen pressure without adding sulfuric acid. By using high temperature and strong oxidation conditions, most of the sulfur in the minerals is oxidized into sulfuric acid. The leaching rates of nickel, copper and cobalt are all greater than 94%, which helps to reduce the processing cost while achieving efficient leaching.

[0050] (2) This invention uses nickel sulfide concentrate as a neutralizing agent, utilizing the gangue components to reduce the acidity of the oxygen pressure leaching solution, and then further leaching the neutralized slag with oxygen pressure. This effectively avoids the loss of nickel, copper, and cobalt metals carried away by the neutralized slag, while utilizing sulfides to remove Fe from the oxygen pressure leaching solution. 3+ Most of it is reduced to Fe 2+ In other words, neutralization and reduction are completed in one process, simplifying the process and equipment. In addition, valuable mineral bodies in the solid material entering the oxygen pressure leaching process are fully exposed, and the volume of solid material entering the oxygen pressure leaching process is also reduced, which can reduce the load on the oxygen pressure leaching equipment, help improve leaching efficiency, improve overall processing efficiency, and save energy.

[0051] (3) The hematite slag produced by this invention contains more than 55% iron and about 6-8% sulfur. It can be sold directly as raw material for cement plants, or it can be sold as iron concentrate after being roasted and desulfurized in a fluidized bed furnace with pyrite. This realizes the resource utilization of iron slag and helps to improve the comprehensive treatment efficiency.

[0052] (4) Typically, the iron content of the neutralized solution is above 20 g / L, and the iron removal efficiency is controlled at 16-24 kg·m³. -3 ·h -1 At a temperature of 185-200℃, more than 40% of the iron in the solution is converted into iron slag in the first reactor and some of it is deposited and slag is formed. Each reactor can serve as a backup for the others. The iron slag is cleaned regularly through the manhole, with a cleaning cycle of up to 30-60 days, which can ensure continuous production.

[0053] The iron content of the solution after treatment by the first reactor is below 20 g / L, and the iron removal efficiency is controlled at 5-7 kg·m³. -3 ·h -1 At a temperature of 165-180℃, approximately 60% of the iron in the remaining solution is converted into iron slag in subsequent reactors, but the iron slag rarely deposits or forms deposits within the reactor. Thus, only the first reactor needs cleaning, without the need to clean subsequent reactors.

[0054] (5) The iron removal method using hematite is simpler and more efficient than the traditional extraction method, which is conducive to industrial application.

[0055] (6) The invention adopts a method of neutralizing nickel sulfide concentrate and then adding water to the neutralizing slag to produce acid at high temperature and strong oxygen, which achieves the purpose of efficient leaching of nickel, copper and cobalt and solves the technical problem of loss of valuable metals carried away by the neutralizing slag. Attached Figure Description

[0056] Figure 1 This is a flowchart of the processing of nickel sulfide concentrate according to the present invention.

[0057] Figure 2 This is the XRD analysis spectrum of the hematite slag obtained in Example 1 of the present invention.

[0058] Figure 3 This is a simplified structural diagram of the iron removal system according to Embodiment 1 of the present invention. Detailed Implementation

[0059] The present invention will be described in detail below with reference to embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in the embodiments of the present invention can be combined with each other. Unless otherwise specified, the relevant percentages refer to mass percentages.

[0060] Example 1

[0061] (1) Nickel sulfide concentrate (containing 7.04% Ni, 3.88% Cu, 0.22% Co, 24.66% Fe, and gangue mainly composed of 7.1% serpentine, 2.8% talc, and 1.2% amphibole) was mixed with oxygen pressure leaching solution at a ratio of 1g:4mL and reacted at 70℃ for 1.0h. After solid-liquid separation, the neutralized liquid (containing 25g / L iron, pH=1) and neutralized residue were obtained.

[0062] (2) After adjusting the neutralization residue with water to a solids concentration of 65 wt%, the slurry is finely ground until 90% of the minerals are less than 20 μm in size. The finely ground slurry is then mixed with raffinate (see...). Figure 1 After mixing the solid and liquid components (from the iron removal liquid extraction process) to obtain a mixed slurry with a solid-liquid ratio of 1g:2mL, the mixed slurry was added to an autoclave, and oxygen was added simultaneously for oxygen pressure leaching (controlled temperature 180℃, pressure 1.5MPa, time 2h). After solid-liquid separation, oxygen pressure leaching solution and oxygen pressure leaching residue were obtained. The oxygen pressure leaching solution contained Ni 33.43g / L, Cu 18.28g / L, Co 1.04g / L, Fe 25.45g / L, and H2SO4 42g / L. The leaching rate of nickel was 94.96%, the leaching rate of copper was 94.24%, and the leaching rate of cobalt was 94.86%.

[0063] The neutralized liquid (pre-iron removal liquid) is fed into the iron removal system for hematite iron removal. See [link to relevant documentation]. Figure 3The iron removal system includes a pump 1, a first valve 8 and a second valve 9, a first pipeline 5, five reactors 2, a second pipeline 6, a third pipeline 7, a fourth pipeline 19, five ninth valves 16, tenth valves 17, twelfth valves 20, a sixth valve 13, a flash tank 3, and a solid-liquid separation unit. The outlet of the pump 1 is connected to the first pipeline 5. The reactor 2 includes a tank body, which is provided with a feed inlet, a discharge inlet, an air inlet, an exhaust outlet (not shown), and a manhole (not shown). The feed inlet and discharge outlet are both located at the top of the tank, while the air inlet is located at the bottom. A stirring mechanism is installed inside the tank. Each feed inlet is connected in parallel to a first pipeline 5, each discharge outlet is connected in parallel to a third pipeline 7, and each air inlet is connected in parallel to a second pipeline 6. A fourth valve 11 and a seventh valve 14 are installed between the first pipeline 5 and the feed inlets. The feed inlet, fourth valve 11, seventh valve 14, and first pipeline 5 are sequentially connected. The pipeline between the fourth valve 11 and the seventh valve 14 is connected to... The third pipeline 7 is connected; a third valve 10 is provided between the second pipeline 6 and the air inlet; a fifth valve 12 is provided between the third pipeline 7 and the discharge port; one port of the ninth valve 16 is connected to the pipeline between the fifth valve 12 and the third pipeline 7, and the other port of the ninth valve 16 is connected to the fourth pipeline 19; an eleventh valve 18 is provided on the third pipeline 7 between the inlet and the discharge port of the same tank, and the eleventh valve 18 is located between the connection position of the fourth valve 11 and the third pipeline 7 of the corresponding tank and the connection position of the fifth valve 12 and the third pipeline 7; in two adjacent tanks, an eighth valve 15 is provided on the third pipeline between the discharge port of the previous tank and the inlet of the next tank; one port of the tenth valve 17 is connected to one end of the third pipeline 7, one port of the twelfth valve 20 is connected to the other end of the third pipeline 7, and the other port of the tenth valve 17 and the other port of the twelfth valve 20 are connected in parallel to the inlet end of the sixth valve 13. The outlet of the first valve 8 and the outlet of the second valve 9 are connected in parallel to one end of the second pipeline 6. A steam source can be connected to the inlet of the first valve 8, and an oxygen source can be connected to the inlet of the second valve 9 to supply oxygen and steam, meeting the requirements of the iron removal reaction and heating. The sixth valve 13, the flash tank 3, and the solid-liquid separation unit are connected in sequence. After the iron removal reaction, the liquid after iron removal is cooled and depressurized in the flash tank, and after concentration separation, the supernatant (the liquid after iron removal) is sent to the subsequent purification-extraction-crystallization-electrowinning process. The reactor is a vertical reaction vessel.

[0064] With 1m 3 The reactor is controlled at a temperature of 185℃ and a pressure of 1.6MPa. The neutralized liquid is fed into the first reactor via pump 1, with the flow rate controlled at 1.82m³. 3 / h, after passing through the first reactor, the solution contains 15g / L of Fe, the residence time is 0.55h, and the iron removal efficiency is 18.2kg / m 3The process produces 18.2 kg of hematite slag (containing 55% iron and 6.2% sulfur); a solution containing 15 g / L of Fe flows sequentially through four subsequent reactors at a rate of 4 × 1 m³ / h. 3 The temperature was controlled at 170℃, the pressure at 1.6MPa, and the solution flow rate was 1.82m³. 3 The final iron content in the liquid after iron removal was 2 g / L, the residence time was 2.2 h, and the iron removal efficiency was 5.92 kg / m³. 3 .h, produced 94.64 kg of hematite slag (containing 55% iron and 6.5% sulfur; its XRD pattern can be found in [reference needed]). Figure 2 The cleaning cycle for the first reactor is 50 days. The specific operations of the above process include: (1) opening the first valve 8 (regulating valve) and the second valve 9 (regulating valve), opening the third valve 10, adjusting the steam flow rate and oxygen flow rate (oxygen concentration greater than 99%), and controlling the reactor temperature and pressure to the target value. (2) opening the pump 1 (pressurizing pump) and the seventh valve 14 corresponding to reactor 1# and the fourth valve 11 of reactor 1#, and pumping the neutralized liquid (pre-iron removal liquid) into reactor 1#2. (3) opening the fifth valve 12, the eighth valve 15 and the sixth valve 13 of reactor 1#2, and after the solution flowing out after being processed by reactors 2#, 3#, 4# and 5#2 in sequence, cooling and depressurizing it through the flash tank 3, and then thickening it to obtain the iron removal liquid and the thickened underflow. The thickened underflow can be centrifuged to obtain hematite slag.

[0065] When it is necessary to clean the iron slag from reactor #1, close valves 11, 12, and 10 of reactor #1 to short-circuit reactor #1. Connect the feed and discharge pipes of reactors #2, #3, #4, and #5 to allow the other four reactors to operate continuously. After reactor #1 is cleaned, open valve 16 of reactor #5, and open valves 16, 12, 11, and 17 of reactor #1. The solution flowing out after being processed by reactors #2, #3, #4, #5, and #1 (2) is cooled and depressurized in flash tank 3 and then thickened to obtain the iron-removed liquid and thickened underflow. The thickened underflow can be centrifuged to obtain hematite slag.

[0066] Example 2

[0067] Nickel sulfide concentrate (containing 6.95% Ni, 3.78% Cu, 0.25% Co, and 22.15% Fe) was mixed with oxygen pressure leaching solution at a ratio of 1 g: 4 mL. After reacting at 80 °C for 1.5 h, the solid and liquid were separated to obtain a neutralized liquid (containing 21 g / L of iron, pH = 1.5) and a neutralized residue. Then, the neutralized residue was mixed with water to a solids concentration of 70 wt%. The slurry was then finely ground until 90% of the mineral particles were less than 20 μm. The finely ground slurry and the raffinate were mixed at a solid-liquid ratio of 1 g: 2.5 mL and added to an autoclave. Oxygen was added simultaneously for oxygen pressure leaching (temperature controlled at 190℃, pressure at 1.60 MPa, time at 2.5 h). After solid-liquid separation, oxygen pressure leaching solution and oxygen pressure leaching residue were obtained. The oxygen pressure leaching solution contained 26.62 g / L Ni, 14.34 g / L Cu, 0.95 g / L Co, 21.38 g / L Fe, and 46 g / L H2SO4. The leaching rates of nickel, copper, and cobalt were 95.76%, 94.84%, and 95.26%, respectively.

[0068] The neutralized liquid (pre-iron removal liquid) is fed into the iron removal system (the specific structure is the same as the iron removal system in Example 1) to remove iron from the hematite, at a concentration of 1m³. 3 The reactor is controlled at a temperature of 185℃ and a pressure of 1.6MPa, with a flow rate of 2m³ after neutralization. 3 After passing through the first reactor, the solution contained 13 g / L of Fe, with a residence time of 0.5 h and an iron removal efficiency of 16.0 kg·m³. -3 ·h -1 The process produces 14.55 kg of hematite slag (containing 55% iron and 7% sulfur). A solution containing 13 g / L of Fe flows sequentially through four subsequent reactors at a rate of 4 × 1 m³ / min. 3 The temperature was controlled at 165℃, the pressure at 1.60MPa, and the solution flow rate was 2m³ / h. 3 The final iron content in the liquid after iron removal was 1.9 g / L, with a residence time of 2 hours and an iron removal efficiency of 5.5 kg·m³. -3 ·h -180 kg of hematite slag (containing 55% iron and 6.6% sulfur) was produced. The cleaning cycle of the first reactor was 60 days. The specific operation of the above process includes: (1) opening the first valve 8 (regulating valve) and the second valve 9 (regulating valve), opening the third valve 10, adjusting the steam flow rate and oxygen flow rate (oxygen concentration greater than 99%), and controlling the reactor temperature and pressure to the target value. (2) opening the pump 1 (pressurizing pump) and the seventh valve 14 corresponding to reactor 1# and the fourth valve 11 of reactor 1#, and pumping the neutralized liquid (liquid before iron removal) into reactor 1#2. (3) opening the fifth valve 12, the eighth valve 15 and the sixth valve 13 of reactor 1#2, and after the solution flowing out after being treated by reactors 2#, 3#, 4# and 5#2 in sequence, cooling and depressurizing it through the flash tank 3, and then thickening it to obtain the liquid after iron removal and the thickened underflow. The thickened underflow can be centrifuged to obtain hematite slag.

[0069] The above embodiments should be understood as being used only to illustrate the present invention more clearly, and not to limit the scope of the present invention. After reading the present invention, any modifications of the present invention in various equivalent forms by those skilled in the art fall within the scope defined by the appended claims.

Claims

1. A method for removing iron from nickel sulfide concentrate by oxygen leaching, characterized in that, Includes the following steps: S1. Mix the nickel sulfide concentrate to be treated with oxygen pressure leaching solution, react at 65-85℃ for 1-2 hours, then separate the solid and liquid to obtain neutralized slag and neutralized liquid. S2. After oxygen pressure leaching treatment of the neutralized residue, solid-liquid separation is performed to obtain oxygen pressure leaching solution and oxygen pressure leaching residue. After the neutralized liquid is treated with iron removal by the hematite method, solid-liquid separation is performed to obtain the iron-removed liquid and hematite slag. Among them, the oxygen pressure leachate is returned to S1.

2. The oxygen leaching iron removal method according to claim 1, characterized in that, In S1, the reaction is carried out at 68-82°C, preferably at 70-80°C.

3. The oxygen leaching iron removal method according to claim 1, characterized in that, In S1, the nickel sulfide concentrate to be processed contains Ni ≥ 1 wt%, Cu 0-10 wt%, Co 0-10 wt%, and Fe 0.5-35 wt%; preferably, Ni 2-15 wt%, Cu 1-6 wt%, Co 0.05-5 wt%, and Fe 1-30 wt%.

4. The oxygen leaching iron removal method according to claim 1, characterized in that, In S1, the nickel sulfide concentrate to be treated is mixed with oxygen pressure leaching solution at a solid-liquid ratio of 1g:2-6mL.

5. The oxygen leaching iron removal method according to claim 1, characterized in that, In S2, the neutralized residue is first mixed with water and finely ground to obtain a finely ground slurry. Then, the slurry is adjusted to obtain a diluted slurry with a solid-liquid mass ratio of 1g:2-6mL before oxygen pressure leaching. Among them, the proportion of mineral particles with a particle size of less than 20 μm in the solid phase of finely ground slurry is ≥90 wt%. Preferably, the water is pure water or raffinate; Preferably, the water used for slurry preparation is pure water or raffinate.

6. The oxygen leaching iron removal method according to any one of claims 1-5, characterized in that, In S2, oxygen pressure leaching is carried out without the addition of acid; preferably, oxygen with a concentration of 55 vol% or more is introduced during oxygen pressure leaching.

7. The oxygen leaching iron removal method according to any one of claims 1-5, characterized in that, In S2, during oxygen pressure leaching, the temperature is controlled at 180-190℃, the pressure at 1.5-1.6 MPa, and the time at 2.0-3.0 h.

8. The oxygen leaching iron removal method according to any one of claims 1-5, characterized in that, In S2, the oxygen pressure leaching is either a single-stage oxygen pressure leaching or a multi-stage oxygen pressure leaching.

9. The oxygen leaching iron removal method according to any one of claims 1-5, characterized in that, In S2, during the iron precipitation treatment, oxygen with a concentration ≥90 vol% is introduced into the neutralized liquid, and the temperature is controlled at 165-200℃, the pressure at 1.6-1.8 MPa, and the time at 2.5-4.0 h. Preferably, every 1m 3 The oxygen flow rate into the neutralized solution is 3-4 Nm³. 3 .

10. The oxygen leaching method for iron removal according to any one of claims 1-5, characterized in that, In S2, iron removal is performed through an iron removal system, which includes a first pipeline (5), N reactors (2), a second pipeline (6), a third pipeline (7), a fourth pipeline (19), N ninth valves (16), tenth valves (17), twelfth valves (20), and a solid-liquid separation unit. The reactors (2) include a tank with an inlet, a outlet, an air inlet, and a manhole. A stirring mechanism is provided inside the tank. Each inlet is connected to the first pipeline (5), each outlet is connected to the third pipeline (7), and each air inlet is connected to the second pipeline (6). A fourth valve (11) and a seventh valve (14) are provided between the first pipeline (5) and the inlet. The door (11), the seventh valve (14) and the first pipeline (5) are connected in sequence. The pipeline between the fourth valve (11) and the seventh valve (14) is connected to the third pipeline (7). The second pipeline (6) and the air inlet are provided with a third valve (10). The third pipeline (7) and the discharge port are provided with a fifth valve (12). One port of the ninth valve (16) is connected to the pipeline between the fifth valve (12) and the third pipeline (7). The other port of the ninth valve (16) is connected to the fourth pipeline (19). The third pipeline (7) between the inlet and the discharge port of the same tank is provided with an eleventh valve (18). The third pipeline (7) between two adjacent tanks is provided with an eighth valve (15). One port of the tenth valve (17) is connected to one end of the third pipeline (7), one port of the twelfth valve (20) is connected to the other end of the third pipeline (7), and the other port of the tenth valve (17) and the other port of the twelfth valve (20) are connected in parallel to the inlet end of the solid-liquid separation unit; Where N is an integer ≥ 2; Preferably, the neutralized liquid flows sequentially through the N reactors; when the iron content of the neutralized liquid entering the first reactor is >20 g / L, the iron removal efficiency is controlled at 16-24 kg·m³. -3 ·h -1 The temperature is 185-200℃, the residence time is 0.15-1h, and a solution with an iron content of <20g / L is obtained. The iron removal efficiency of the subsequent N-1 reactors should be controlled at 5-7 kg·m³. -3 ·h -1 The total residence time in reactor N-1 is 1.5-3 hours, and the temperature is 165-180℃.

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