Iron removal method for laterite-nickel ore leaching pulp

Abstract

The invention discloses an iron removal method for laterite-nickel ore leaching pulp, and relates to the technical field of laterite-nickel ore hydrometallurgy. The iron removal method comprises the following steps that the pH value of laterite-nickel ore leaching ore pulp is adjusted to A1, a first mixture is introduced for a first reaction, and first intermediate liquid is obtained; adjusting the pH value of the first intermediate solution to A2, and introducing the second mixture to carry out a second reaction to obtain a second intermediate solution; adjusting the pH value of the second intermediate solution to A3, and carrying out a third reaction to obtain a third intermediate solution; wherein A1 < A2 < A3 < = 6, the first mixture and the second mixture both comprise SO2-containing substances and O2-containing gas, the ferrous content of leached ore pulp can be effectively reduced, and therefore the purity and quality of nickel-cobalt precipitates are improved.

Description

Technical Field

[0001] The present application relates to the technical field of laterite nickel ore hydrometallurgy, and in particular to a method for removing iron from laterite nickel ore leaching slurry. Background Art

[0002] Laterite nickel ore contains rich nickel. Currently, the main method of extracting nickel from laterite nickel ore is hydrometallurgy. The hydrometallurgy usually includes washing, beneficiation, high-pressure acid leaching, impurity removal of leached slurry, metal precipitation and other steps. Among them, high-pressure acid leaching refers to mixing the pretreated laterite nickel ore with a leaching agent (such as sulfuric acid, hydrochloric acid, etc.) to convert the nickel and cobalt therein into soluble nickel-cobalt salts. The leached slurry contains a certain amount of ferrous ions. The presence of ferrous ions seriously affects the stability of the subsequent precipitation of nickel-cobalt metal precipitation process, resulting in large fluctuations in the amount of nickel and cobalt and the impurity content in the precipitated nickel-cobalt hydroxide product, affecting the quality of the nickel-cobalt product. In order to improve the extraction rate and purity of nickel and cobalt, it is necessary to remove ferrous iron from the leached slurry.

[0003] At present, in the process of impurity removal, the divalent iron is generally converted into trivalent iron by adding hydrogen peroxide or introducing air, and then precipitated into slag, so as to achieve the purpose of iron removal. However, these methods have the problems of high cost and low utilization rate of oxidants, low iron removal rate, and affect the quality of nickel cobalt hydroxide products. Therefore, it is necessary to provide an efficient and low-cost iron removal method to improve the quality of nickel cobalt hydroxide products. Summary of the invention

[0004] The main purpose of the present application is to provide a method for removing iron from laterite nickel ore leaching slurry, so as to solve the problems of high cost and low removal rate of existing iron removal methods.

[0005] In order to achieve the above object, one aspect of the present application provides a method for removing iron from laterite nickel ore leaching slurry, and the method for removing iron from laterite nickel ore leaching slurry comprises:

[0006] S1, adjusting the pH value of the laterite nickel ore leaching slurry to A1, and introducing the first mixture into the slurry for a first reaction to obtain a first intermediate solution;

[0007] S2, adjusting the pH value of the first intermediate solution to A2, and introducing the second mixture into the first intermediate solution for a second reaction to obtain a second intermediate solution;

[0008] S3, adjusting the pH value of the second intermediate solution to A3, performing a third reaction, and obtaining a third intermediate solution;

[0009] Wherein, A1<A2<A3≤6, the first mixture and the second mixture both contain SO 2 Substances and O 2 of gas.

[0010] Further, A1 is 1 to 3, A2 is 3 to 5, and A3 is 4 to 6;

[0011] Preferably, A1 is 1.5 to 2.5, A2 is 3.2 to 4.2, and A3 is 4.2 to 5.2.

[0012] Further, the gas-liquid volume ratio of the first mixture to the laterite nickel ore leaching slurry is (0.1-40):1; and / or,

[0013] The gas-liquid volume ratio of the second mixture to the first intermediate liquid is (0.1-40):1;

[0014] Preferably, the gas-liquid volume ratio of the first mixture to the laterite nickel ore leaching slurry is (1-10):1; and / or,

[0015] Preferably, the gas-liquid volume ratio of the second mixture to the first intermediate liquid is (1-10):1.

[0016] Furthermore, SO 2 Substances include pure SO 2 、Containing SO 2 Flue gas can produce SO 2 One of the reagents; the reagent containing O 2 The gas includes pure O 2 , one in the air;

[0017] Preferably, SO in the first mixture 2 The volume concentration is 0.5% to 25%;

[0018] Preferably, SO in the second mixture 2 The volume concentration is 0.5% to 25%;

[0019] Preferably, in the first mixture, 2 The volume concentration is 10% to 50%;

[0020] Preferably, the second mixture contains O 2 The volume concentration is 10% to 50%;

[0021] Preferably, it is possible to generate SO 2 The reagents include metabisulfite, sulfite, metabisulfite solution, sulfite solution, liquid SO 2 One of;

[0022] More preferably, it is possible to generate SO 2 The reagents include Na 2 S 2 O 5 , containing Na 2 S 2 O 5Solution, Na 2 SO 3 , containing Na 2 SO 3 One of the solutions.

[0023] Further, the temperature of the first reaction is 70-95° C. and the time is 2-8 hours; and / or,

[0024] The second reaction temperature is 60-80°C and the time is 2-8h; and / or,

[0025] The temperature of the third reaction is 50-70° C., and the time is 2-8 hours.

[0026] Furthermore, the method for removing iron from laterite nickel ore leaching slurry also includes:

[0027] S1 also includes performing a first countercurrent washing on the laterite nickel ore leaching slurry; and / or,

[0028] Before S2, the first intermediate liquid is also subjected to a second countercurrent washing.

[0029] Furthermore, the number of stages of the first countercurrent washing is 3 to 8; the mass ratio of the washing water used in the first countercurrent washing to the solid in the laterite nickel ore leaching slurry is (2 to 4): 1; and / or,

[0030] The number of stages of the second countercurrent washing is 3 to 8; the mass ratio of the washing water used in the second countercurrent washing to the solid in the first intermediate liquid is (2 to 4):1.

[0031] Furthermore, after the second reaction, the second reaction product is transported to a thickener for first sedimentation, and the supernatant is collected as the second intermediate liquid; and / or,

[0032] After the third reaction, the third reaction product is transported to a thickener for second sedimentation, and the supernatant is collected, which is the third intermediate liquid.

[0033] Furthermore, the method for removing iron from laterite nickel ore leaching slurry further comprises the following steps:

[0034] S4, mixing the third intermediate solution with a precipitant to perform a precipitation reaction to obtain a nickel-cobalt precipitate;

[0035] Preferably, the precipitant comprises an alkaline substance;

[0036] More preferably, the precipitant comprises NaOH, CaO, Ca(OH) 2 At least one of KOH

[0037] Furthermore, the temperature of the laterite nickel ore leaching pulp is 70-100°C, the acid concentration is 15-60g / L, the Ni concentration is 0.5-15g / L, the Co concentration is 0.1-2g / L, and the Fe 2+ The concentration is 0.5~15g / L, Fe 3+ The concentration is 0.5~15g / L, the Al concentration is 0.5~10g / L, the Mn concentration is 0.5~10g / L, and the Mg concentration is 0.5~20g / L.

[0038] Apply the technical solution of this application, using SO 2 Substances and substances containing O 2 The gas is used as an oxidant and the pH value is gradually increased to remove Fe 2+ The iron is gradually oxidized and precipitated, effectively reducing the ferrous content of the leached slurry, thereby improving the purity and quality of the nickel-cobalt precipitate. In addition, the iron removal method provided by the present application also has the advantages of low oxidant cost, high efficiency, and easy availability. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 The present invention is a process flow chart of a method for removing iron from laterite nickel ore leaching slurry in one embodiment of the present application. DETAILED DESCRIPTION

[0040] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below in conjunction with the embodiments.

[0041] As described in the background technology, the existing iron removal methods have the problems of high cost and low removal rate. Figure 1 As shown, the present application provides a method for removing iron from laterite nickel ore leaching slurry, and the method for removing iron from laterite nickel ore leaching slurry comprises:

[0042] S1, adjusting the pH value of the laterite nickel ore leaching slurry to A1, and introducing the first mixture into the slurry for a first reaction to obtain a first intermediate solution;

[0043] S2, adjusting the pH value of the first intermediate solution to A2, and introducing the second mixture into the first intermediate solution for a second reaction to obtain a second intermediate solution;

[0044] S3, adjusting the pH value of the second intermediate solution to A3, performing a third reaction, and obtaining a third intermediate solution;

[0045] Wherein, A1<A2<A3≤6, the first mixture and the second mixture both contain SO 2 Substances and O 2 of gas.

[0046] Laterite nickel ore is an ore containing elements such as nickel and iron. Hydrometallurgical process is an effective method for extracting nickel and cobalt from laterite nickel ore, mainly including steps such as pretreatment, leaching, and precipitation. Wherein, pretreatment is to carry out pretreatments such as ore washing to laterite nickel ore, and leaching refers to mixing the pretreated laterite nickel ore with a leaching agent (such as sulfuric acid, hydrochloric acid, etc.) to dissolve the metal elements therein, and obtain a leached slurry (i.e., laterite nickel ore leaching slurry) containing elements such as nickel and cobalt. In the leaching process, in addition to dissolving nickel and cobalt elements, a certain amount of ferrous iron will also be dissolved. In order to obtain a nickel-cobalt precipitate with high purity, it is necessary to carry out ferrous iron removal treatment to the leached slurry, to remove the iron element therein, and finally the purified leached slurry is precipitated, and elements such as nickel and cobalt therein are precipitated to form a precipitate.

[0047] The iron removal method of the laterite nickel ore leaching slurry of the present application is mainly aimed at removing the iron element in the laterite nickel ore leaching slurry. The iron removal method can be used in conjunction with the hydrometallurgical process of the laterite nickel ore, that is, it can be arranged after the leaching step and before the precipitation step in the hydrometallurgical process to achieve the purpose of purification.

[0048] Since an excessive amount of acidic leaching agent is used in the leaching process, the leached slurry contains a large amount of acidic residual acid. In S1, the pH value of the laterite nickel ore leaching slurry is adjusted to A1 to achieve the purpose of neutralizing the residual acid, and at the same time, the first mixture is introduced for the first reaction to remove Fe 2+ Oxidized to Fe 3+ In S2, the pH value of the first intermediate solution is adjusted to A2, mainly to precipitate impurities such as Fe, Al, and Si therein, and at the same time, the second mixture is introduced for the second reaction, the purpose of which is to further precipitate Fe 2+ Oxidized to Fe 3+ In S3, the pH value of the second intermediate solution is adjusted to A3, the main purpose of which is to further precipitate impurities such as Fe, Al, and Si therein.

[0049] Among them, A1<A2<A3≤6, that is, the pH value increases, and the first mixture and the second mixture both contain SO 2 Substances and O 2 That is, the first mixture and the second mixture may contain only SO 2 and O 2 , or SO 2 , O 2 A mixture with other gases, or a system that can produce SO 2 Substances and substances containing O 2 A gas mixture containing SO 2 and O 2 That's it.

[0050] In the specific implementation process of the present application, the laterite nickel ore leaching slurry or the first intermediate liquid is substantially mixed with SO 2 and O 2 A reaction occurs.

[0051] This application uses SO 2 Substances and O 2 The gas is used as an oxidant and the pH value is gradually increased to remove Fe 2+ The iron is gradually oxidized and precipitated, effectively reducing the ferrous content of the leached slurry, thereby improving the purity and quality of the nickel-cobalt precipitate. In addition, the iron removal method provided by the present application also has the advantages of low oxidant cost, high efficiency, and easy availability.

[0052] The present application does not limit the specific value of the pH value, which can be adjusted according to the actual situation, as long as A1<A2<A3≤6 is ensured. In some embodiments, A1 is 1 to 3, A2 is 3 to 5, and A3 is 4 to 6. By limiting the specific numerical ranges of A1, A2, and A3, the iron content can be further reduced, and the purity and quality of the subsequently formed nickel-cobalt precipitate can be improved.

[0053] Specifically, A1 is 1 to 3, such as 1, 1.5, 2, 2.5, 3 or any two thereof, A2 is 3 to 5, such as 3, 3.5, 4, 4.5, 5 or any two thereof, and A3 is 4 to 6, such as 4, 4.5, 5, 5.5, 6 or any two thereof. In some preferred embodiments, A1 is 1.5 to 2.5, A2 is 3.2 to 4.2, and A3 is 4.2 to 5.2.

[0054] This application can be achieved by adding CaCO 3 The pH value is adjusted by using calcium carbonate (also called calcium carbonate or limestone).

[0055] The present application does not limit the amount of the first mixture and the second mixture introduced, which can be determined according to the actual volume of the liquid to be treated. For example, in some embodiments, the gas-liquid volume ratio of the first mixture to the laterite nickel ore leaching slurry is (0.1-40):1; and / or, the gas-liquid volume ratio of the second mixture to the first intermediate liquid is (0.1-40):1. By limiting the volume ratio of the first mixture, the second mixture and the corresponding liquid to be treated, both the precipitation rate of iron and the treatment efficiency can be improved.

[0056] Specifically, the gas-liquid volume ratio of the first mixture to the laterite nickel ore leaching slurry is (0.1-40):1, such as 0.1:1, 1:1, 5:1, 10:1, 20:1, 30:1, 40:1 or any two thereof; and / or, the gas-liquid volume ratio of the second mixture to the first intermediate solution is (0.1-40):1, such as 0.1:1, 1:1, 5:1, 10:1, 20:1, 30:1, 40:1 or any two thereof. In some preferred embodiments, the gas-liquid volume ratio of the first mixture to the laterite nickel ore leaching slurry is (1-10):1; and / or, the gas-liquid volume ratio of the second mixture to the first intermediate solution is (1-10):1.

[0057] The gas-liquid volume ratio of the first mixture to the laterite nickel ore leaching slurry refers to the ratio of the total gas volume of the first mixture to the total liquid volume of the laterite nickel ore leaching slurry. The gas-liquid volume ratio of the second mixture to the first intermediate liquid refers to the ratio of the total gas volume of the second mixture to the total liquid volume of the first intermediate liquid.

[0058] In some embodiments, SO 2 Substances include pure SO 2 、Containing SO 2 Flue gas can produce SO 2 One of the reagents containing O 2 The gas includes pure O 2 , a specific type of air containing SO 2 Substances include pure SO 2 、Containing SO 2 Flue gas can produce SO 2 One of the reagents containing O 2 The gas includes pure O 2 , one of the air. Among them, SO 2 Flue gas can be generated by coal-fired power plants, oil refineries, metal smelters, sulfuric acid plants, vehicle exhaust, industrial boilers, etc. Coal, oil, ore, sulfur-containing fuels, etc. contain sulfur, which reacts with oxygen to generate SO during combustion. 2 , forming SO 2 Flue gas. Can produce SO 2 The reagent is one that can produce SO under acidic conditions. 2 of reagents.

[0059] The first mixture can be pure SO 2 A mixture with air, which can be pure SO 2 With pure O 2 mixture, which may contain SO 2 The mixture of flue gas and air can be SO 2 The smoke and O2 mixture, can be capable of producing SO 2 The mixture of reagent and air can be capable of producing SO 2 The reagents and pure O 2 Similarly, the second mixture can be pure SO 2 A mixture with air, which can be pure SO 2 With pure O 2 mixture, which may contain SO 2 The mixture of flue gas and air can be SO 2 Flue gas and pure O 2 mixture, can be capable of producing SO 2 The mixture of reagent and air can be capable of producing SO 2 The reagents and pure O 2 In this way, the cost of the oxidant can be further reduced.

[0060] Specifically, when the first mixture is pure SO 2 mixture with air, the total gas volume of the first mixture is pure SO 2 and air; when the first mixture is pure SO 2 With pure O 2 The total gas volume of the first mixture is pure SO 2 With pure O 2 When the first mixture contains SO 2 The total volume of the first mixture is a mixture of flue gas and air containing SO 2 The sum of the volumes of flue gas and air; when the first mixture is SO 2 Flue gas and pure O 2 The total volume of the gas in the first mixture is SO 2 Flue gas and pure O 2 When the first mixture is capable of producing SO 2 The total volume of the first mixture is sufficient to produce SO 2 The reagent can generate SO 2 volume and the volume of air; when the first mixture is capable of producing SO 2 The reagents and pure O 2 The total volume of the gas in the first mixture is sufficient to produce SO 2 The reagent can generate SO 2 Volume and pure O 2 The sum of the volumes of .

[0061] Similarly, when the second mixture is pure SO 2mixture with air, the total gas volume of the second mixture is pure SO 2 and air; when the second mixture is pure SO 2 With pure O 2 The total gas volume of the second mixture is pure SO 2 With pure O 2 When the second mixture contains SO 2 The total volume of the second mixture is a mixture of flue gas and air containing SO 2 The sum of the volumes of flue gas and air; when the second mixture is SO 2 Flue gas and pure O 2 The total volume of the gas in the second mixture is SO 2 Flue gas and pure O 2 When the second mixture is capable of producing SO 2 The total volume of the second mixture is sufficient to produce SO 2 The reagent can generate SO 2 volume and the volume of air; when the second mixture is capable of producing SO 2 The reagents and pure O 2 The total volume of the gas in the second mixture is sufficient to produce SO 2 The reagent can generate SO 2 Volume and pure O 2 The sum of the volumes of .

[0062] The present application does not limit the amount of SO in the first mixture and the second mixture. 2 The volume concentration can be adjusted according to the actual situation. For example, in some embodiments, SO 2 The volume concentration of SO in the second mixture is 0.5% to 25%. 2 The volume concentration of SO in the first mixture and the second mixture is 0.5% to 25%. 2 The volume concentration is 0.5% to 25%, which can further improve the iron removal rate and improve the utilization rate of the oxidant.

[0063] Specifically, SO in the first mixture 2 The volume concentration of SO in the second mixture is 0.5% to 25%, for example, 0.5%, 1%, 5%, 10%, 15%, 20%, 25% or any two thereof; SO 2 The volume concentration is 0.5% to 25%, for example, 0.5%, 1%, 5%, 10%, 15%, 20%, 25% or a range consisting of any two thereof.

[0064] The first mixture of SO 2The volume concentration refers to the SO 2 Or the generated SO 2 The volume percentage of the total volume of the first mixture gas is, for example, when the first mixture contains SO 2 The mixture of flue gas and air, the first mixture contains SO 2 The volume concentration of SO 2 The ratio of the volume to the total volume of the first mixture gas; when the first mixture is capable of producing SO 2 A mixture of reagent and air, the first mixture contains SO 2 The volume concentration is sufficient to produce SO 2 The reagent can generate SO 2 The ratio of the volume to the total volume of the first mixed gas, and so on.

[0065] Furthermore, when the first mixture is pure SO 2 Or containing SO 2 When the flue gas and air are mixed, the first mixture contains SO 2 The volume concentration of SO is preferably 0.5% to 5%. 2 Or containing SO 2 Flue gas and pure O 2 When the mixture is first mixed with SO 2 The volume concentration is preferably 5% to 25%.

[0066] The present application does not limit the amount of O in the first mixture and the second mixture. 2 volume concentration, as long as it contains O 2 For example, in some embodiments, the first mixture contains O 2 The volume concentration of the second mixture is 15% to 30%, for example, 15%, 20%, 25%, 30% or any two thereof; 2 The volume concentration is 15% to 30%, for example, 15%, 20%, 25%, 30% or a range consisting of any two thereof.

[0067] Capable of generating SO 2 The reagent is a SO 2 In some embodiments, the reagent capable of producing SO 2 The reagents include metabisulfite, sulfite, metabisulfite solution, sulfite solution, liquid SO 2 Preferably, it can produce SO 2 The reagents include Na 2 S 2 O 5 , containing Na 2 S 2O 5 Solution, Na 2 SO 3 , containing Na 2 SO 3 One of the solutions.

[0068] The present application does not limit the specific conditions of the first reaction, the second reaction and the third reaction. For example, in some embodiments, the temperature of the first reaction is 70-95°C and the time is 2-8h; and / or, the temperature of the second reaction is 60-80°C and the time is 2-8h; and / or, the temperature of the third reaction is 50-70°C and the time is 2-8h. By limiting each reaction condition, the reaction rate can be increased, thereby improving the processing efficiency.

[0069] Specifically, the temperature of the first reaction is 70-95°C, for example 70°C, 75°C, 80°C, 85°C, 90°C, 95°C or a range consisting of any two thereof, and the time is 2-8h, for example 2h, 4h, 5h, 6h, 7h, 8h or a range consisting of any two thereof; and / or, the temperature of the second reaction is 60-80°C, for example 60°C, 65°C, 70°C, 75°C, 80°C or a range consisting of any two thereof, and the time is 2-8h, for example 2h, 4h, 5h, 6h, 7h, 8h or a range consisting of any two thereof; and / or, the temperature of the third reaction is 50-70°C, for example 50°C, 55°C, 60°C, 65°C, 70°C or a range consisting of any two thereof, and the time is 2-8h, for example 2h, 4h, 5h, 6h, 7h, 8h or a range consisting of any two thereof.

[0070] In order to further improve the purity and quality of the subsequently formed nickel-cobalt precipitate, the solid precipitate in the leached slurry needs to be separated before the first reaction or after the first reaction and before the second reaction. In some embodiments, before S1, the laterite nickel ore leaching slurry is further subjected to a first countercurrent washing; and / or before S2, the first intermediate solution is further subjected to a second countercurrent washing.

[0071] Specifically, when S1 also includes subjecting the laterite nickel ore leaching slurry to a first countercurrent washing, the laterite nickel ore leaching slurry is subjected to a first countercurrent washing to obtain a first overflow solution and a first underflow slurry; the pH value of the first overflow solution is adjusted to A1, and the first mixture is introduced to carry out a first reaction.

[0072] When S2 also includes performing a second countercurrent washing on the first intermediate liquid, the first intermediate liquid is subjected to a second countercurrent washing to obtain a second overflow solution and a second underflow slurry; the pH value of the second overflow solution is adjusted to A2, and the second mixture is introduced to perform a second reaction.

[0073] Among them, countercurrent washing refers to making the liquid containing solid particles flow in the opposite direction to the washing water to improve the separation efficiency of solid particles. In the countercurrent washing process, the liquid overflowing from the top is the overflow solution, which usually contains a lower concentration of solid particles because the heavier particles are deposited at the bottom under the countercurrent. The slurry discharged from the bottom is the underflow slurry, which usually contains a higher concentration of solid particles because the heavier particles are deposited at the bottom under the countercurrent.

[0074] The present application may use a multi-stage thickener to implement countercurrent washing to achieve more efficient separation. The multi-stage thickener uses the principle of gravity sedimentation to allow the solid particles in the slurry to settle to the bottom, thereby separating the slurry into a clear liquid and a high concentration of solids. The multi-stage thickener is usually composed of multiple thickening tanks. The slurry undergoes multiple first countercurrent washings in multiple thickening tanks to gradually improve the separation efficiency. In each thickening tank, the liquid to be treated and the washing water are in countercurrent contact. Specifically, CCD countercurrent washing can be used. In some embodiments, the number of stages of the first countercurrent washing is 3 to 8; the mass ratio of the washing water used in the first countercurrent washing to the solids in the laterite nickel ore leaching slurry is (2 to 4): 1; and / or, the number of stages of the second countercurrent washing is 3 to 8; the mass ratio of the washing water used in the second countercurrent washing to the solids in the first intermediate liquid is (2 to 4): 1. Such separation to different degrees helps to improve the separation efficiency and improve the treatment efficiency.

[0075] During the second reaction and the third reaction, iron-aluminum slag is produced. In some embodiments, after the second reaction, the second reaction product is transported to a thickener for a first sedimentation, and the supernatant is collected, which is the second intermediate liquid; and / or, after the third reaction, the third reaction product is transported to a thickener for a second sedimentation, and the supernatant is collected, which is the third intermediate liquid. During the first sedimentation and the second sedimentation, the heavier iron-aluminum slag settles to the bottom, and after solid-liquid separation, the supernatant is collected through an overflow tank to obtain the second intermediate liquid and the third intermediate liquid.

[0076] The third intermediate liquid of the present application is essentially the supernatant liquid after removing the iron and aluminum slag, and contains nickel and cobalt with high purity. Through precipitation treatment, a nickel and cobalt precipitate with high purity can be obtained. In some embodiments, the method for removing iron from laterite nickel ore leaching slurry also includes the following steps: S4, mixing the third intermediate liquid with a precipitant, performing a precipitation reaction, and obtaining a nickel and cobalt precipitate; preferably, the precipitant includes an alkaline substance; in some preferred embodiments, the precipitant includes at least one of sodium hydroxide NaOH, CaO, Ca(OH)2, KOH, and MgO.

[0077] The desired nickel and cobalt products can be obtained by thickening and filtering the nickel and cobalt precipitates. Thickening is to thicken the nickel and cobalt precipitates to increase the solid concentration; then the thickened underflow is filtered to obtain the nickel and cobalt-containing products.

[0078] The laterite nickel ore leaching slurry of the present application can be leached in the laterite nickel ore hydrometallurgical process. In some embodiments, the temperature of the laterite nickel ore leaching slurry is 70-100° C., the acid concentration is 15-60 g / L, the Ni concentration is 0.5-15 g / L, the Co concentration is 0.1-2 g / L, and the Fe 2+ The concentration is 0.5~15g / L, Fe 3+ The concentration is 0.5-15 g / L, the Al concentration is 0.5-10 g / L, the Mn concentration is 0.5-10 g / L, and the Mg concentration is 0.5-20 g / L. If the acid leaching agent used in the leaching step is sulfuric acid, the acid concentration refers to the sulfuric acid concentration.

[0079] The present application is further described in detail below in conjunction with specific embodiments. These embodiments should not be construed as limiting the scope of protection claimed in the present application.

[0080] Example 1

[0081] The leaching pulp of a laterite nickel ore high pressure acid leaching selected in this embodiment contains high pressure acid leaching residue, wherein the dry weight of the high pressure acid leaching residue accounts for 30.3% of the total weight, that is, the solid concentration is 30.3%, the Ni concentration in the liquid phase is 4.1g / L, the Co concentration is 0.6g / L, and the Fe concentration is 1.3g / L. 2+ Concentration 5.1g / L, Fe 3+ The concentration is 1.5g / L, the Al concentration is 3.0g / L, the Mn concentration is 3.6g / L, and the Mg concentration is 9.4g / L.

[0082] The above laterite nickel ore leaching slurry is subjected to the following iron removal method:

[0083] Step 1: Pump the laterite nickel ore leaching slurry into the pre-neutralization tank. At 95°C, add limestone to the pre-neutralization tank to adjust the pH value to 2.0. While adding limestone, introduce air and pure SO into the leaching slurry. 2 The mixed gas is used for preliminary oxidation and iron removal. The amount of mixed gas is 8.47m3 per cubic meter of liquid. 3 , where SO 2 The volume concentration is 2%, O 2 The volume concentration is 20.6%, the reaction time is 4h, and the first intermediate solution is obtained;

[0084] Step 2: Pump the first intermediate liquid in step 1 into a 6-stage CCD for countercurrent washing to obtain an overflow solution; the mass ratio of washing water to solids in the first intermediate liquid is 2.5:1;

[0085] Step 3: Pump the overflow solution obtained in step 2 into a first-stage iron and aluminum removal tank. At 70°C, add limestone to the first-stage iron and aluminum removal tank to adjust the pH value to 3.6. At the same time, introduce air and SO into the solution. 2 Mixed gas, where the amount of mixed gas is 3.16m3 per cubic meter of liquid 3 , SO in the mixed gas 2 The volume concentration is 1.899%, O 2 The volume concentration is 20.6%, the reaction time is 3h, and after the reaction, it is pumped into a first-stage iron and aluminum removal thickener, and after solid-liquid separation, a first-stage iron and aluminum removal liquid is obtained;

[0086] Step 4: The first stage iron removal and aluminum removal liquid in step 3 is pumped into the second stage iron removal and aluminum removal tank, and the pH is adjusted to 4.9 by adding limestone slurry at 60°C to the second stage iron removal and aluminum removal tank, and the reaction time is 3h. After the reaction, it is pumped into the second stage iron removal and aluminum removal thickener, and after solid-liquid separation, the second stage iron removal and aluminum removal liquid is obtained;

[0087] Step 5: The liquid after the second stage iron and aluminum removal in step 4 is pumped into the nickel and cobalt precipitation process, sodium hydroxide is added, and a crude nickel and cobalt hydroxide product is obtained after nickel and cobalt precipitation and pressure filtration.

[0088] After the above process, the Fe 2+ The content is 0.005g / L, and the iron content in the nickel cobalt hydroxide product is 0.04%.

[0089] Example 2

[0090] The leaching pulp of a laterite nickel ore high pressure acid leaching selected in this embodiment contains high pressure acid leaching residue, wherein the dry weight of the high pressure acid leaching residue accounts for 29.8% of the total weight, that is, the solid concentration is 29.8%, and the Ni content in the liquid phase is 3.9 g / L, the Co content is 0.6 g / L, and the Fe content is 1.3 g / L. 2+ The content is 5.6g / L, the Al content is 3.1g / L, the Mn concentration is 3.3g / L, and the Mg concentration is 9.1g / L.

[0091] The above laterite nickel ore leaching slurry is subjected to the following iron removal method:

[0092] Step 1: sending the laterite nickel ore leaching slurry into a 6-stage CCD for countercurrent washing to obtain an overflow solution; the mass ratio of the washing water to the solid in the first intermediate solution is 2.5:1;

[0093] Step 2: Pump the overflow liquid obtained in step 1 into the pre-neutralization tank. At 95°C, add limestone to the pre-neutralization tank to adjust the pH value to 2.0. While adding limestone, introduce air and SO into the leached slurry. 2 The mixed gas is used for preliminary oxidation and iron removal, wherein the amount of mixed gas is 7.34m3 per cubic meter of liquid. 3, SO in the mixed gas 2 Volume concentration 1.907%, O 2 The volume concentration is 20.6%, the reaction time is 4h, and the first intermediate solution is obtained;

[0094] Step 3: The first intermediate solution obtained in step 2 is sent to a first iron and aluminum removal tank. At a temperature of 70°C, limestone is added to the first iron and aluminum removal tank to adjust the pH value to 3.6. At the same time, air and SO are introduced into the solution. 2 Mixed gas, where the amount of mixed gas is 2.14m3 per cubic meter of liquid 3 , SO in the mixed gas 2 The volume concentration is 1.869%, O 2 The volume concentration is 20.6%, the reaction time is 3h, and after the reaction, it is pumped into a first-stage iron and aluminum removal thickener, and after solid-liquid separation, a first-stage iron and aluminum removal liquid is obtained;

[0095] Step 4: The first stage iron removal and aluminum removal liquid in step 3 is pumped into the second stage iron removal and aluminum removal tank, and the pH is adjusted to 4.9 by adding limestone slurry at 60°C to the second stage iron removal and aluminum removal tank, and the reaction time is 3h. After the reaction, it is pumped into the second stage iron removal and aluminum removal thickener, and after solid-liquid separation, the second stage iron removal and aluminum removal liquid is obtained;

[0096] Step 5: The liquid after the second stage iron and aluminum removal in step 4 is pumped into the nickel and cobalt precipitation process, sodium hydroxide is added, and a crude nickel and cobalt hydroxide product is obtained after nickel and cobalt precipitation and pressure filtration.

[0097] After the above process, the Fe 2+ The content is 0.005g / L, and the iron content in the nickel cobalt hydroxide product is 0.04%.

[0098] Example 3

[0099] The difference from Example 1 is that in step 1, limestone is added to the pre-neutralization tank to adjust the pH value to 1.5; in step 3, limestone is added to the first-stage iron and aluminum removal tank to adjust the pH value to 3.2; in step 4, limestone slurry is added to the second-stage iron and aluminum removal tank to adjust the pH to 4.2.

[0100] After the above process, the Fe 2+ The content is 0.010g / L, and the iron content in the nickel cobalt hydroxide product is 0.07%.

[0101] Example 4

[0102] The difference from Example 1 is that in step 1, limestone is added to the pre-neutralization tank to adjust the pH value to 2.5; in step 3, limestone is added to the first-stage iron and aluminum removal tank to adjust the pH value to 4.2; in step 4, limestone slurry is added to the second-stage iron and aluminum removal tank to adjust the pH value to 5.2.

[0103] After the above process, the Fe 2+ The content is 0.004g / L, and the iron content in the nickel cobalt hydroxide product is 0.03%.

[0104] Example 5

[0105] The difference from Example 1 is that in step 1, limestone is added to the pre-neutralization tank to adjust the pH value to 1; in step 3, limestone is added to the first-stage iron and aluminum removal tank to adjust the pH value to 3; in step 4, limestone slurry is added to the second-stage iron and aluminum removal tank to adjust the pH to 4.

[0106] After the above process, the Fe 2+ The content is 0.150g / L, and the iron content in the nickel cobalt hydroxide product is 1.4%.

[0107] Example 6

[0108] The difference from Example 1 is that in step 1, limestone is added to the pre-neutralization tank to adjust the pH value to 3; in step 3, limestone is added to the first-stage iron and aluminum removal tank to adjust the pH value to 5; in step 4, limestone slurry is added to the second-stage iron and aluminum removal tank to adjust the pH to 6.

[0109] After the above process, the Fe 2+ The content is 0.004g / L, and the iron content in the nickel-cobalt hydroxide product is 0.03%. Due to the high pH, ​​the smelting yield of valuable metals Ni and Co is reduced.

[0110] Example 7

[0111] The difference from Example 1 is that in step 1, the amount of mixed gas is 12.6m3 per cubic meter of liquid. 3 In step 3, the amount of mixed gas is 4.7m3 per cubic meter of liquid. 3 .

[0112] After the above process, the Fe 2+ The content is 0.002g / L, and the iron content in the nickel cobalt hydroxide product is 0.02%.

[0113] Example 8

[0114] The difference from Example 1 is that in step 1, the amount of mixed gas is 4.2m3 per cubic meter of liquid. 3 In step 3, the amount of mixed gas is 1.5m3 per cubic meter of liquid. 3 .

[0115] After the above process, the Fe 2+The content is 0.04g / L, and the iron content in the nickel cobalt hydroxide product is 0.4%.

[0116] Example 9

[0117] The difference from Example 1 is that in step 1, air and SO2-containing gas are introduced into the leaching slurry while adding limestone. 2 The mixed gas with a volume ratio of 10% flue gas is initially oxidized to remove iron. SO 2 The volume concentration is 2%, O 2 The volume concentration is 18.8%; in step 3, air and SO 2 The volume ratio of the flue gas mixture is 10%, and the SO 2 The volume concentration is 2%, O 2 The volume concentration is 18.8%.

[0118] After the above process, the Fe 2+ The content is 0.012g / L, and the iron content in the nickel cobalt hydroxide product is 0.08%.

[0119] Example 10

[0120] The difference from Example 1 is that in step 1, sodium metabisulfite Na is added to the leaching slurry while adding limestone. 2 S 2 O 5 Air is introduced for preliminary oxidation and iron removal. The air consumption is 8.30m3 per cubic meter of liquid. 3 , Na 2 S 2 O 5 The SO generated in 2 The volume is 2% of the volume of air; in step 3, sodium metabisulfite Na is added to the solution at the same time. 2 S 2 O 5 Air is introduced, and the air consumption is 3.10m3 per cubic meter of liquid. 3 , Na 2 S 2 O 5 The SO generated in 2 The volume is 2% of the volume of air.

[0121] After the above process, the Fe 2+ The content is 0.011 g / L, and the iron content in the nickel cobalt hydroxide product is 0.07%.

[0122] Comparative Example 1

[0123] The difference from Example 1 is that in step 1 and step 3, "air and SO2 "Mixed gas" is replaced by "air", that is, only air is introduced;

[0124] In this comparative example, the Fe 2+ The content is 2.53g / L, and the iron content in the nickel cobalt hydroxide product is 20.4%.

[0125] Comparative Example 2

[0126] The difference from Example 1 is that in step 1 and step 3, "air and SO 2 The mixture of "O 2 ", that is, only O 2 .

[0127] In this comparative example, the Fe 2+ The content is 1.40g / L, and the iron content in the nickel cobalt hydroxide product is 12.3%.

[0128] According to the above embodiments and comparative examples, the present invention uses SO 2 Substances and O 2 The gas is used as an oxidant and the pH value is gradually increased to remove Fe 2+ The iron is gradually oxidized and precipitated, effectively reducing the ferrous content of the leached slurry, thereby improving the purity and quality of the nickel-cobalt precipitate. In addition, the iron removal method provided by the present application also has the advantages of low oxidant cost, high efficiency, and easy availability.

[0129] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those described herein, for example.

[0130] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for removing iron from laterite nickel ore leaching slurry, characterized in that: The iron removal method of the laterite nickel ore leaching slurry comprises: S1, adjusting the pH value of the laterite nickel ore leaching slurry to A1, and introducing the first mixture into the slurry for a first reaction to obtain a first intermediate solution; S2, adjusting the pH value of the first intermediate solution to A2, and introducing the second mixture into the first intermediate solution for a second reaction to obtain a second intermediate solution; S3, adjusting the pH value of the second intermediate solution to A3, performing a third reaction, and obtaining a third intermediate solution; Among them, A1<A2<A3≤6, and the first mixture and the second mixture both include gases containing SO2 substances and gases containing O2.

2. The iron removal method according to claim 1, characterized in that: A1 is 1 to 3, A2 is 3 to 5, and A3 is 4 to 6; Preferably, A1 is 1.5 to 2.5, A2 is 3.2 to 4.2, and A3 is 4.2 to 5.

2.

3. The iron removal method according to claim 1, characterized in that: The gas-liquid volume ratio of the first mixture to the laterite nickel ore leaching slurry is (0.1-40):1; and / or, The gas-liquid volume ratio of the second mixture to the first intermediate liquid is (0.1-40):1; Preferably, the gas-liquid volume ratio of the first mixture to the laterite nickel ore leaching slurry is (1-10):1; and / or, Preferably, the gas-liquid volume ratio of the second mixture to the first intermediate liquid is (1-10):

1.

4. The iron removal method according to claim 1, characterized in that: The SO2-containing substance includes one of pure SO2, flue gas containing SO2, and a reagent capable of generating SO2; the O2-containing gas includes one of pure O2 and air; Preferably, the volume concentration of SO2 in the first mixture is 0.5% to 25%; Preferably, the volume concentration of SO2 in the second mixture is 0.5% to 25%; Preferably, the volume concentration of O2 in the first mixture is 10% to 50%; Preferably, the volume concentration of O2 in the second mixture is 10% to 50%; Preferably, the reagent capable of producing SO2 comprises one of pyrosulfite, sulfite, pyrosulfite solution, sulfite solution, and liquid SO2; More preferably, the reagent capable of producing SO2 includes one of Na2S2O5, a solution containing Na2S2O5, Na2SO3, and a solution containing Na2SO3.

5. The iron removal method according to claim 1, characterized in that: The temperature of the first reaction is 70-95° C. and the time is 2-8 hours; and / or, The temperature of the second reaction is 60-80° C. and the time is 2-8 hours; and / or, The temperature of the third reaction is 50-70° C. and the time is 2-8 hours.

6. The iron removal method according to any one of claims 1 to 5, characterized in that: S1 also includes performing a first countercurrent washing on the laterite nickel ore leaching slurry; and / or, Before S2, the first intermediate liquid is also subjected to a second countercurrent washing.

7. The iron removal method according to claim 6, characterized in that: The number of stages of the first countercurrent washing is 3 to 8; the mass ratio of the washing water used in the first countercurrent washing to the solid in the laterite nickel ore leaching slurry is (2 to 4): 1; and / or, The number of stages of the second countercurrent washing is 3 to 8; the mass ratio of the washing water used in the second countercurrent washing to the solids in the first intermediate liquid is (2 to 4):

1.

8. The iron removal method according to claim 6, characterized in that: After the second reaction, the second reaction product is transported to a thickener for first sedimentation, and a supernatant is collected, which is a second intermediate liquid; and / or, After the third reaction, the third reaction product is transported to a thickener for second sedimentation, and the supernatant is collected, which is the third intermediate liquid.

9. The iron removal method according to claim 6, characterized in that: The iron removal method of the laterite nickel ore leaching slurry also includes: S4, mixing the third intermediate solution with a precipitant to perform a precipitation reaction to obtain a nickel-cobalt precipitate; Preferably, the precipitant comprises an alkaline substance; More preferably, the precipitant comprises at least one of NaOH, CaO, Ca(OH)2, and KOH.

10. The iron removal method according to claim 6, characterized in that: The temperature of the laterite nickel ore leaching pulp is 70-100° C., the acid concentration is 15-60 g / L, the Ni concentration is 0.5-15 g / L, the Co concentration is 0.1-2 g / L, the Fe concentration is 0.5-15 g / L, the 2+ The concentration is 0.5~15g / L, Fe 3+ The concentration is 0.5~15g / L, the Al concentration is 0.5~10g / L, the Mn concentration is 0.5~10g / L, and the Mg concentration is 0.5~20g / L.

Images