Process and system for recovering manganese from high pressure leaching system of laterite nickel ore

Abstract

The application discloses a process and system for recovering manganese in a high-pressure leaching system of laterite nickel ore, and comprises the following steps: S1. limestone is added to the high-pressure leaching liquid of the laterite nickel ore for pre-neutralization to obtain first-stage carbon dioxide and a neutralization liquid, the limestone is added for iron and aluminum precipitation to obtain second-stage carbon dioxide and a slurry, liquid alkali is added to the slurry for nickel, cobalt and manganese precipitation to obtain nickel cobalt manganese hydroxide and a nickel cobalt manganese precipitation lean liquid; S2. the first-stage carbon dioxide and the second-stage carbon dioxide are collected and introduced into the nickel cobalt manganese precipitation lean liquid, the pH value of the nickel cobalt manganese precipitation lean liquid is adjusted to 5-6.5 by liquid alkali, and then a precipitation reaction is carried out to obtain a crude manganese carbonate product; S3. the crude manganese carbonate product is dissolved by sulfuric acid to obtain a dissolved liquid and third-stage carbon dioxide, the dissolved liquid is subjected to calcium and magnesium removal treatment to obtain a manganese sulfate solution, and then evaporation crystallization is carried out to obtain manganese sulfate crystals; the third-stage carbon dioxide is reused and introduced into the nickel cobalt manganese precipitation lean liquid; the recovery rate of the manganese is high, and carbon emission of the laterite nickel ore leaching process is reduced.

Description

Technical Field

[0001] This invention relates to the field of manganese recovery technology, and in particular to a process and system for recovering manganese from a high-pressure leaching system for laterite nickel ore. Background Technology

[0002] In the high-pressure leaching process of laterite nickel ore, nickel and cobalt are selectively leached under high temperature and pressure. Simultaneously, valuable metals associated with the ore, such as Mn, Mg, and Cr, are also dissolved and enter the leachate. Mn, as a key metallic element in ternary batteries, also has recovery value. The laterite nickel ore undergoes a series of processes including "ore beneficiation pretreatment - high-pressure leaching - pre-neutralization - CCD washing - iron and aluminum removal - nickel-cobalt-manganese precipitation" to produce nickel-cobalt-manganese hydroxide, achieving the goal of manganese recovery.

[0003] However, because the pH of the nickel-cobalt-manganese precipitate solution is between 7 and 8, while the pH required for Mn to form hydroxide through alkaline precipitation exceeds 8.6, the Mn content in the finished nickel-cobalt-manganese hydroxide product is relatively low compared to Ni, approximately (6-9%). This leaves about 1.3 g / L of Mn remaining in the liquid phase. Direct discharge of this Mn would pollute the environment, while wastewater treatment would increase production costs.

[0004] Therefore, it is necessary to design a scheme to recover Mn from the precipitated nickel-cobalt-manganese lean solution, improve economic efficiency, and at the same time make the wastewater meet the standards for discharge and reuse. Summary of the Invention

[0005] In view of this, this application provides a process and system for recovering manganese in a high-pressure leaching system for laterite nickel ore, which has a high manganese recovery rate and utilization rate and reduces carbon emissions from the laterite nickel ore leaching process.

[0006] To achieve the above technical objectives, this application adopts the following technical solution:

[0007] In a first aspect, this application provides a method for recovering manganese from a high-pressure leaching system for laterite nickel ore, comprising the following steps:

[0008] S1. Limestone is added to the high-pressure leaching solution of laterite nickel ore for pre-neutralization to obtain a first stage of carbon dioxide and neutralization solution. Limestone is added to the neutralization solution to precipitate iron and aluminum to obtain a second stage of carbon dioxide and slurry. Liquid alkali is added to the slurry to precipitate nickel, cobalt and manganese to obtain nickel, cobalt and manganese hydroxide and lean solution of precipitated nickel, cobalt and manganese.

[0009] S2. Collect the first and second stages of carbon dioxide and pass them into the lean solution of nickel cobalt manganese precipitation. Adjust the pH of the lean solution of nickel cobalt manganese precipitation to 5-6.5 using liquid alkali, and then carry out the precipitation reaction to obtain crude manganese carbonate.

[0010] S3. Dissolve crude manganese carbonate with sulfuric acid to obtain a solution and three stages of carbon dioxide. Then, treat the solution to remove calcium and magnesium to obtain a manganese sulfate solution. Evaporate and crystallize to obtain manganese sulfate crystals. Reuse the three stages of carbon dioxide and pass them into a lean solution of nickel, cobalt and manganese precipitation.

[0011] Preferably, in step S3, the calcium and magnesium removal steps are as follows:

[0012] S31. Add an extractant to the solution and perform countercurrent extraction, then separate the loaded organic phase. After washing with sulfuric acid, the first organic phase and calcium sulfate solution are obtained.

[0013] S32. The first organic phase is back-extracted using the second sulfuric acid to obtain the second organic phase and a magnesium sulfate solution;

[0014] S33. The second organic phase is back-extracted again using the third sulfuric acid to obtain a manganese sulfate solution and a fourth organic phase; the fourth organic phase is reused and passed into the dissolving solution.

[0015] Preferably, the extractant includes one or more of P507, P204, Cyanex272, Cyanex923, TBP, and P350.

[0016] Preferably, the concentration of the first sulfuric acid is 0.03-0.05 mol / L, the concentration of the second sulfuric acid is 0.8-1.0 mol / L, and the concentration of the third sulfuric acid is 1.5-1.8 mol / L.

[0017] Preferably, in step S1, the pH of the liquid phase after countercurrent extraction is 3-4.

[0018] Preferably, the extractant is saponified prior to countercurrent extraction.

[0019] Preferably, in step S1, the pH value of the nickel-cobalt-manganese precipitate lean solution is 7-8.

[0020] Preferably, the precipitation reaction time is 30-60 minutes.

[0021] Secondly, this application provides a system for recovering manganese from a high-pressure leaching system of laterite nickel ore, comprising a carbon dioxide storage tank and, in sequence, a pre-neutralization tank, an iron-aluminum precipitator tank, a nickel-cobalt-manganese precipitator tank, a first reaction tank, a second reaction tank, a filter press, and a dissolving and impurity removal tank; the carbon dioxide storage tank and the pre-neutralization tank are connected by a section of carbon dioxide conveying pipeline, the carbon dioxide storage tank and the iron-aluminum precipitator tank are connected by a second section of carbon dioxide conveying pipeline, the carbon dioxide storage tank and the dissolving and impurity removal tank are connected by a third section of carbon dioxide conveying pipeline, the carbon dioxide storage tank and the first reaction tank are connected by a first carbon dioxide conveying pipeline, and the carbon dioxide storage tank and the second reaction tank are connected by a second carbon dioxide conveying pipeline; the first carbon dioxide conveying pipeline is provided with a first control valve for controlling the carbon dioxide conveying flow rate, the second carbon dioxide conveying pipeline is provided with a second control valve for controlling the carbon dioxide conveying flow rate, and a third control valve is provided between the nickel-cobalt-manganese precipitator tank and the first reaction tank for controlling the conveying flow rate of the nickel-cobalt-manganese lean solution.

[0022] Preferably, the first reaction vessel is externally connected to a first online pH monitor, a first online 3S-CL-Mn manganese ion analyzer, and a first automatic liquid alkali adder; the second reaction vessel is externally connected to a second online pH monitor, a second online 3S-CL-Mn manganese ion analyzer, and a second automatic liquid alkali adder; the first and second automatic liquid alkali adders are equipped with valves for controlling the flow rate of liquid alkali delivery.

[0023] The beneficial effects of this application are as follows:

[0024] 1. This scheme combines the carbon dioxide produced in the laterite nickel ore production line with the recovery of high levels of Mn in the lean nickel cobalt manganese precipitate solution, thereby reducing the carbon emissions of the entire process, achieving green production and significant economic benefits.

[0025] 2. This method can convert Mn in lean nickel-cobalt-manganese electrolyte into manganese carbonate byproduct with high purity and high recovery rate;

[0026] 3. This solution reduces the difficulty of wastewater treatment in laterite nickel ore production lines. Compared with using only pH control to remove manganese, this solution has a better sedimentation effect and consumes less neutralizing agent. Attached Figure Description

[0027] Figure 1 This is the process flow diagram for this solution;

[0028] Figure 2 This is a process flow diagram for removing calcium and magnesium.

[0029] Figure 3A schematic diagram of a high-pressure leaching system for recovering manganese from laterite nickel ore; in the diagram, 1. pre-neutralization tank; 2. iron-aluminum immersion tank; 7. nickel-cobalt-manganese immersion tank; 3. first reaction tank; 4. second reaction tank; 5. filter press; 6. dissolution and impurity removal tank; 8. carbon dioxide storage tank; 31. first online pH monitor; 33. 3S-CL-Mn manganese ion online analyzer; 32. first automatic liquid alkali adder; 41. second online pH monitor; 43. second 3S-CL-Mn manganese ion online analyzer; 42. second automatic liquid alkali adder. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0031] like Figure 1 As shown, this application provides a method for recovering manganese from a high-pressure leaching system of laterite nickel ore, comprising the following steps:

[0032] S1. Limestone is added to the high-pressure leaching solution of laterite nickel ore for pre-neutralization to obtain a first stage of carbon dioxide and neutralization solution. Limestone is added to the neutralization solution to precipitate iron and aluminum to obtain a second stage of carbon dioxide and slurry. Liquid alkali is added to the slurry to precipitate nickel, cobalt and manganese to obtain nickel, cobalt and manganese hydroxide and lean solution of precipitated nickel, cobalt and manganese.

[0033] S2. Collect the first and second stages of carbon dioxide and pass them into the lean solution of nickel cobalt manganese precipitation. Adjust the pH of the lean solution of nickel cobalt manganese precipitation to 5-6.5 using liquid alkali, and then carry out the precipitation reaction to obtain crude manganese carbonate.

[0034] S3. Dissolve crude manganese carbonate with sulfuric acid to obtain a solution and three stages of carbon dioxide. Then, treat the solution to remove calcium and magnesium to obtain a manganese sulfate solution. Evaporate and crystallize to obtain manganese sulfate crystals. Reuse the three stages of carbon dioxide and pass them into a lean solution of nickel, cobalt and manganese precipitation.

[0035] In the entire leaching process of laterite nickel ore to produce nickel-cobalt-manganese hydroxide, limestone is added during the pre-neutralization and precipitation of iron and aluminum to consume residual acid and adjust the pH of the solution. As the limestone is consumed, a large amount of greenhouse gas carbon dioxide is generated. The carbon dioxide generated in the two steps is recovered and introduced into the lean solution after the nickel-cobalt-manganese precipitation. Then, the pH value of the lean solution is controlled and maintained at 5-6.5 with the help of liquid alkali. After the precipitation reaction takes 30-60 minutes, white manganese carbonate precipitate appears. At the same time, most of the Mg remains in the liquid phase and is removed, resulting in a high-purity crude manganese carbonate by-product.

[0036] After the above steps, the crude manganese carbonate has a high manganese content, but still contains a small amount of Ca and Mg impurities, with Ca impurities accounting for about 2-4% and Mg impurities accounting for about 1-2%. In order to further purify the manganese carbonate, this method also removes calcium and magnesium from the crude manganese carbonate.

[0037] like Figure 2 As shown, in step S3, the steps for removing calcium and magnesium are as follows:

[0038] S31. Add an extractant to the solution and perform countercurrent extraction, then separate the loaded organic phase. After washing with sulfuric acid, the first organic phase and calcium sulfate solution are obtained.

[0039] S32. The first organic phase is back-extracted using the second sulfuric acid to obtain the second organic phase and a magnesium sulfate solution;

[0040] S33. The second organic phase is back-extracted again using the third sulfuric acid to obtain a manganese sulfate solution and a fourth organic phase; the fourth organic phase is reused and passed into the dissolving solution.

[0041] The manganese element in the solution was extracted and enriched by the extractant. After three-stage countercurrent extraction, the loaded organic phase was washed with sulfuric acid to remove Ca. Then, the first organic phase was back-extracted with sulfuric acid to selectively remove Mg. Finally, the second organic phase was back-extracted with sulfuric acid to remove Mn. The final manganese sulfate solution had almost no calcium and magnesium impurities.

[0042] The extractants include one or more of P507, P204, Cyanex272, Cyanex923, TBP, and P350.

[0043] The concentration of the first sulfuric acid is 0.03-0.05 mol / L, and suitable but not limitingly, the concentration of the first sulfuric acid is 0.03 mol / L, 0.04 mol / L, or 0.05 mol / L; the concentration of the second sulfuric acid is 0.8-1.0 mol / L, and suitable but not limitingly, the concentration of the second sulfuric acid is 0.8 mol / L, 0.9 mol / L, or 1.0 mol / L; the concentration of the third sulfuric acid is 1.5-1.8 mol / L, and suitable but not limitingly, the concentration of the third sulfuric acid is 1.5 mol / L, 1.6 mol / L, or 1.8 mol / L.

[0044] Prior to countercurrent extraction, the extractant is also saponified.

[0045] In step S1, the pH of the liquid phase after countercurrent extraction is 3-4, which depends on the pH value of the extractant after saponification. In this application, the pH value of the extractant after saponification is 3-4.

[0046] In step S1, the pH value of the nickel-cobalt-manganese precipitate lean solution is 7-8; in order to achieve the best nickel-cobalt precipitation effect, the pH value of the slurry is adjusted to 7-8 by liquid alkali.

[0047] The precipitation reaction takes 20-30 minutes.

[0048] This application provides a system for recovering manganese from a high-pressure leaching system of laterite nickel ore, comprising a carbon dioxide storage tank 8 and a pre-neutralization tank 1, an iron-aluminum immersion tank 2, a nickel-cobalt-manganese immersion tank 7, a first reaction tank 3, a second reaction tank 4, a filter press 5, and a dissolution and impurity removal tank 6 connected in sequence; the carbon dioxide storage tank 8 is connected to the pre-neutralization tank 1 via a section of carbon dioxide delivery pipeline, the carbon dioxide storage tank 8 is connected to the iron-aluminum immersion tank 2 via a second section of carbon dioxide delivery pipeline, the carbon dioxide storage tank 8 is connected to the dissolution and impurity removal tank 6 via a third section of carbon dioxide delivery pipeline, the carbon dioxide storage tank 8 is connected to the first reaction tank 3 via a first carbon dioxide delivery pipeline, and the carbon dioxide storage tank 8 is connected to the second reaction tank 4 via a second carbon dioxide delivery pipeline; the first carbon dioxide delivery pipeline is equipped with a first control valve for controlling the carbon dioxide delivery flow rate, the second carbon dioxide delivery pipeline is equipped with a second control valve for controlling the carbon dioxide delivery flow rate, and a third control valve is provided between the nickel-cobalt-manganese immersion tank 7 and the first reaction tank 3 for controlling the delivery flow rate of the nickel-cobalt-manganese lean solution. The first reaction vessel 3 is externally connected to a first online pH monitor 31, a first online 3S-CL-Mn manganese ion analyzer 33, and a first automatic liquid alkali adder 32. The second reaction vessel 4 is externally connected to a second online pH monitor 41, a second online 3S-CL-Mn manganese ion analyzer 43, and a second automatic liquid alkali adder 42. The first automatic liquid alkali adder 32 and the second automatic liquid alkali adder 42 are equipped with valves for controlling the flow rate of liquid alkali. The online pH monitor, the online 3S-CL-Mn manganese ion analyzer, and the automatic liquid alkali adder are all known devices commonly used in the prior art.

[0049] The following specific embodiments further illustrate this solution.

[0050] Example 1

[0051] A method for recovering manganese from a high-pressure leaching system of laterite nickel ore includes the following steps:

[0052] S1. Limestone is added to 100L of high-pressure leaching solution of laterite nickel ore for pre-neutralization to obtain a first stage of carbon dioxide and neutralization solution. Limestone is added to the neutralization solution to precipitate iron and aluminum to obtain a second stage of carbon dioxide and slurry. Liquid alkali is added to the slurry to adjust the pH value to 7 for precipitating nickel, cobalt and manganese to obtain nickel, cobalt and manganese hydroxide and 100L of lean solution for precipitating nickel, cobalt and manganese.

[0053] S2. Collect the first and second stages of carbon dioxide and pass them into the lean solution of nickel cobalt manganese precipitation. Adjust the pH of the lean solution of nickel cobalt manganese precipitation to 5 using liquid alkali, and then carry out the precipitation reaction for 30 minutes to obtain crude manganese carbonate.

[0054] S3. Dissolve crude manganese carbonate in sulfuric acid to obtain a solution and three stages of carbon dioxide. Then, treat the solution to remove calcium and magnesium, yielding 2.5 L of manganese sulfate solution. Evaporate and crystallize to obtain manganese sulfate crystals. Reuse the three stages of carbon dioxide and pass it through a lean nickel-cobalt-manganese precipitate solution. The calcium and magnesium removal steps are as follows:

[0055] S31. Add P507 extractant to the solution and saponify the extractant. The pH of the saponified extractant is 3. Perform countercurrent extraction and separate the loaded organic phase. After washing with 0.03 mol / L sulfuric acid, the first organic phase and calcium sulfate solution are obtained.

[0056] S32. The first organic phase is back-extracted using a second sulfuric acid with a concentration of 0.8 mol / L to obtain the second organic phase and a magnesium sulfate solution;

[0057] S33. The second organic phase is back-extracted again using a third sulfuric acid with a concentration of 1.5 mol / L to obtain a manganese sulfate solution and a fourth organic phase; the fourth organic phase is reused and passed into the dissolving solution.

[0058] Example 2

[0059] A method for recovering manganese from a high-pressure leaching system of laterite nickel ore includes the following steps:

[0060] S1. Limestone is added to 100L of high-pressure leaching solution of laterite nickel ore for pre-neutralization to obtain a first stage of carbon dioxide and neutralization solution. Limestone is added to the neutralization solution to precipitate iron and aluminum to obtain a second stage of carbon dioxide and slurry. Liquid alkali is added to the slurry to adjust the pH value to 8 to precipitate nickel, cobalt and manganese to obtain nickel, cobalt and manganese hydroxide and 100L of lean solution for precipitating nickel, cobalt and manganese.

[0061] S2. Collect the first and second stages of carbon dioxide and pass them into the lean solution of nickel cobalt manganese precipitation. Adjust the pH of the lean solution of nickel cobalt manganese precipitation to 6.5 using liquid alkali, and then carry out the precipitation reaction for 60 min to obtain crude manganese carbonate.

[0062] S3. Dissolve crude manganese carbonate in sulfuric acid to obtain a solution and three stages of carbon dioxide. Then, treat the solution to remove calcium and magnesium, yielding 2.5 L of manganese sulfate solution. Evaporate and crystallize to obtain manganese sulfate crystals. Reuse the three stages of carbon dioxide and pass it through a lean nickel-cobalt-manganese precipitate solution. The calcium and magnesium removal steps are as follows:

[0063] S31. Add Cyanex272 extractant to the solution and saponify the extractant. The pH of the saponified extractant is 4. Perform countercurrent extraction and separate the loaded organic phase. After washing with 0.05 mol / L sulfuric acid, the first organic phase and calcium sulfate solution are obtained.

[0064] S32. The first organic phase is back-extracted using a second sulfuric acid with a concentration of 1.0 mol / L to obtain the second organic phase and a magnesium sulfate solution;

[0065] S33. The second organic phase is back-extracted again using a third sulfuric acid with a concentration of 1.8 mol / L to obtain a manganese sulfate solution and a fourth organic phase; the fourth organic phase is reused and passed into the dissolving solution.

[0066] Example 3

[0067] A method for recovering manganese from a high-pressure leaching system of laterite nickel ore includes the following steps:

[0068] S1. Limestone is added to 100L of high-pressure leaching solution of laterite nickel ore for pre-neutralization to obtain a first stage of carbon dioxide and neutralization solution. Limestone is added to the neutralization solution to precipitate iron and aluminum to obtain a second stage of carbon dioxide and slurry. Liquid alkali is added to the slurry to adjust the pH value to 7.5 to precipitate nickel, cobalt and manganese to obtain nickel, cobalt and manganese hydroxide and 100L of lean solution for precipitating nickel, cobalt and manganese.

[0069] S2. Collect the first and second stages of carbon dioxide and pass them into the lean solution of nickel cobalt manganese precipitation. Adjust the pH of the lean solution of nickel cobalt manganese precipitation to 6 using liquid alkali, and then carry out the precipitation reaction for 60 minutes to obtain crude manganese carbonate.

[0070] S3. Dissolve crude manganese carbonate in sulfuric acid to obtain a solution and three stages of carbon dioxide. Then, treat the solution to remove calcium and magnesium, yielding 2.5 L of manganese sulfate solution. Evaporate and crystallize to obtain manganese sulfate crystals. Reuse the three stages of carbon dioxide and pass it through a lean nickel-cobalt-manganese precipitate solution. The calcium and magnesium removal steps are as follows:

[0071] S31. Add Cyanex 923 extractant to the solution and saponify the extractant. The pH of the saponified extractant is 3.5. Perform countercurrent extraction and separate the loaded organic phase. After washing with 0.04 mol / L sulfuric acid, the first organic phase and calcium sulfate solution are obtained.

[0072] S32. The first organic phase is back-extracted using a second sulfuric acid with a concentration of 0.9 mol / L to obtain the second organic phase and a magnesium sulfate solution;

[0073] S33. The second organic phase is back-extracted again using a third sulfuric acid with a concentration of 1.6 mol / L to obtain a manganese sulfate solution and a fourth organic phase; the fourth organic phase is reused and passed into the dissolving solution.

[0074] Example 4

[0075] like Figure 3 As shown, a system for recovering manganese from a high-pressure leaching system of laterite nickel ore includes a carbon dioxide storage tank 8 and a pre-neutralization tank 1, an iron-aluminum immersion tank 2, a nickel-cobalt-manganese immersion tank 7, a first reaction tank 3, a second reaction tank 4, a filter press 5, and a dissolution and impurity removal tank 6 connected in sequence. The carbon dioxide storage tank 8 is connected to the pre-neutralization tank 1 via a section of carbon dioxide delivery pipeline, the carbon dioxide storage tank 8 is connected to the iron-aluminum immersion tank 2 via a second section of carbon dioxide delivery pipeline, the carbon dioxide storage tank 8 is connected to the dissolution and impurity removal tank 6 via a third section of carbon dioxide delivery pipeline, the carbon dioxide storage tank 8 is connected to the first reaction tank 3 via a first carbon dioxide delivery pipeline, and the carbon dioxide storage tank 8 is connected to the second reaction tank 4 via a second carbon dioxide delivery pipeline. The first carbon dioxide delivery pipeline is equipped with a first control valve for controlling the carbon dioxide delivery flow rate, the second carbon dioxide delivery pipeline is equipped with a second control valve for controlling the carbon dioxide delivery flow rate, and a third control valve is provided between the nickel-cobalt-manganese immersion tank 7 and the first reaction tank 3 for controlling the delivery flow rate of the lean nickel-cobalt-manganese immersion solution. The first reaction vessel 3 is externally connected to a first online pH monitor 31, a first online 3S-CL-Mn manganese ion analyzer 33, and a first automatic liquid alkali adder 32. The second reaction vessel 4 is externally connected to a second online pH monitor 41, a second online 3S-CL-Mn manganese ion analyzer 43, and a second automatic liquid alkali adder 42. The first automatic liquid alkali adder 32 and the second automatic liquid alkali adder 42 are equipped with valves for controlling the flow rate of liquid alkali.

[0076] In this embodiment, the pre-neutralization tank 1, the iron-aluminum immersion tank 2, and the nickel-cobalt-manganese immersion tank 7 are commonly used equipment in the art. The pre-neutralization tank 1 is used to perform the neutralization treatment of the high-pressure leaching solution of laterite nickel ore. It is provided with an inlet for the high-pressure leaching solution of laterite nickel ore and an outlet for the neutralized slurry. The difference between the pre-neutralization tank 1 and the commonly used pre-neutralization tank 1 is that it is provided with a conveying port for conveying a first stage of carbon dioxide to the carbon dioxide storage tank 8. The iron-aluminum immersion tank 2 is used to perform the impurity removal process of the neutralized slurry. It is provided with an inlet for the neutralized slurry, an iron-aluminum underflow outlet, and an iron-aluminum post-liquid outlet. The difference between the iron-aluminum immersion tank 2 and the commonly used iron-aluminum immersion tank 2 is that it is provided with a conveying port for conveying a second stage of carbon dioxide to the carbon dioxide storage tank 8. The nickel-cobalt-manganese immersion tank 7 is used to perform precipitation treatment on the iron-aluminum post-liquid to extract nickel-cobalt-manganese hydroxide. It includes an iron-aluminum post-liquid inlet. The difference between the iron-aluminum immersion tank 7 and the commonly used nickel-cobalt-manganese immersion tank 7 is that it is provided with a conveying port for conveying the lean nickel-cobalt-manganese immersion solution to the first reaction tank 3. Through the aforementioned device, the carbon dioxide released during the limestone pH adjustment process in the iron and aluminum removal stage is transported to the carbon dioxide storage tank 8. The carbon dioxide produced by the residual acid from the high-pressure leaching of limestone during the pre-neutralization stage, as well as the carbon dioxide released from the tail gas during the combustion of lignite to provide steam in the boiler room, are transported to the carbon dioxide storage tank 8 as the second stage carbon dioxide. The carbon dioxide is then transported to the first reaction tank 3 via the inlet of the storage tank 8 and a compressor. Simultaneously, the pH of the lean solution after nickel, cobalt, and manganese precipitation is 7-8, which is then introduced into the first reaction tank 3. Since the pH of manganese carbonate precipitation (5-6.6), magnesium carbonate precipitation (6.4-8.2), and calcium carbonate precipitation (6.2-7.7) are relatively close, strict control of the solution pH, carbon dioxide injection rate, and alkali addition rate is required to avoid excessive alkalinity leading to high impurity content in the precipitate. The first reaction tank 3 fulfills this function. As a buffer tank, the first reaction tank 3 is externally connected to an online pH monitor, a 3S-CL-Mn manganese ion online analyzer 33, and an automatic alkali additive device. Based on the solution pH, the solution pH is maintained at 5-6.5 to avoid calcium precipitate buildup. 2+ and Mg 2+Excessive impurity ions enter the solid phase. When the solution pH > 6.2, manually close the valve for adding liquid alkali and increase the valve for adding carbon dioxide. When the solution pH < 6.0, manually close the valve for adding carbon dioxide and increase the valve for adding liquid alkali. After the conditions in the first reaction tank 3 are stabilized and balanced, the mixed slurry obtained in the first reaction tank 3 enters the second reaction tank 4. In the second reaction tank 4, precipitation reaction mainly occurs. The second reaction tank 4 is equipped with the same feeding device as the first reaction tank 3. At the same time, the second reaction tank 4 is also externally connected to a pH online monitor, a 3S-CL-Mn manganese ion online analyzer 33, and a liquid alkali automatic additive device to detect the Mn content online and ensure that the Mn content in the liquid phase is > 0.35 g / L. Too low a Mn content will affect the Mn-carbon dioxide binding efficiency and reduce the carbon dioxide utilization rate. When the Mn content in the second reaction tank 4 is <0.35g / L, the transfer rate of the slurry in the second reaction tank 4 to the filter press 5 is accelerated. At the same time, the amount of nickel cobalt lean liquor added through the nickel cobalt manganese precipitator 7 is increased to increase the Mn content. Finally, the slurry enters the filter press 5 to obtain crude manganese carbonate product. The dissolution and impurity removal tank 6 is connected to the filter press 5 and is used to receive the crude manganese carbonate product. After adding the dissolving liquid, the generated three-stage carbon dioxide is input into the carbon dioxide storage tank 8.

[0077] Comparative Example 1

[0078] A method for recovering manganese from a high-pressure leaching system of laterite nickel ore includes the following steps:

[0079] Limestone was added to 100L of high-pressure leaching solution of laterite nickel ore for pre-neutralization, resulting in a first stage of carbon dioxide and neutralization solution. Limestone was added to the neutralization solution to precipitate iron and aluminum, resulting in a second stage of carbon dioxide and slurry. Liquid alkali was added to the slurry to adjust the pH to 7 for precipitating nickel, cobalt and manganese, resulting in nickel, cobalt and manganese hydroxide and 100L of lean solution for precipitating nickel, cobalt and manganese. The first stage and second stage of carbon dioxide were discharged.

[0080] The components of the liquid phases obtained in Examples 1-3 and Comparative Example 1 were tested and compared with those in the high-pressure leaching solution of the raw material laterite nickel ore. The results are shown in Table 1.

[0081] Table 1. Component Test Results

[0082]

[0083] The results above show that the liquid phase obtained in this application is a manganese sulfate solution, and the manganese content is all higher than >50 g / L, while the calcium and magnesium content is all <1*10 g / L. -4 g / L, while the liquid phase of Comparative Example 1 contained a large amount of impurities such as manganese, calcium, and magnesium, resulting in poor manganese recovery and low purity.

[0084] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for recovering manganese from a high-pressure leaching system of laterite nickel ore, characterized in that, Includes the following steps: S1. Limestone is added to the high-pressure leaching solution of laterite nickel ore for pre-neutralization to obtain a first stage of carbon dioxide and neutralization solution. Limestone is added to the neutralization solution to precipitate iron and aluminum to obtain a second stage of carbon dioxide and slurry. Liquid alkali is added to the slurry to precipitate nickel, cobalt and manganese to obtain nickel, cobalt and manganese hydroxide and lean solution of precipitated nickel, cobalt and manganese. S2. Collect the first and second stages of carbon dioxide and pass them into the nickel-cobalt-manganese precipitate lean solution. Adjust the pH of the nickel-cobalt-manganese precipitate lean solution to 5-6.5 using liquid alkali, and then carry out the precipitation reaction to obtain crude manganese carbonate. S3. Dissolve the crude manganese carbonate using sulfuric acid to obtain a solution and three stages of carbon dioxide. Then, treat the solution to remove calcium and magnesium to obtain a manganese sulfate solution, which is then evaporated and crystallized to obtain manganese sulfate crystals. The three stages of carbon dioxide are reused and passed into the nickel-cobalt-manganese lean solution. In step S3, the steps for removing calcium and magnesium are as follows: S31. Add an extractant to the solution for countercurrent extraction and separate the loaded organic phase. After washing with sulfuric acid, a first organic phase and a calcium sulfate solution are obtained. S32. The first organic phase is back-extracted using the second sulfuric acid to obtain the second organic phase and a magnesium sulfate solution; S33. The second organic phase is back-extracted again using a third sulfuric acid solution to obtain a manganese sulfate solution and a fourth organic phase; the fourth organic phase is reused and passed into the solution for countercurrent extraction; The extractant includes one or more of P507, P204, Cyanex272, and Cyanex923; The concentration of the first sulfuric acid is 0.03-0.05 mol / L, the concentration of the second sulfuric acid is 0.8-1.0 mol / L, and the concentration of the third sulfuric acid is 1.5-1.8 mol / L.

2. The method for recovering manganese from a high-pressure leaching system of laterite nickel ore according to claim 1, characterized in that, In step S31, the pH of the liquid phase after countercurrent extraction is 3-4.

3. The method for recovering manganese from a high-pressure leaching system of laterite nickel ore according to claim 1, characterized in that, Prior to countercurrent extraction, the extractant is saponified.

4. The method for recovering manganese from a high-pressure leaching system of laterite nickel ore according to claim 1, characterized in that, In step S1, the pH value of the nickel-cobalt-manganese precipitated solution is 7-8.

5. The method for recovering manganese from a high-pressure leaching system of laterite nickel ore according to claim 1, characterized in that, The precipitation reaction takes 30-60 minutes.

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