CN114686702A - One-pot method for purifying magnesium from serpentine atmospheric sulfuric acid leaching solution - Google Patents

Abstract

The invention belongs to the field of mineral resource utilization, and particularly discloses a method for purifying magnesium from a serpentine normal-pressure sulfuric acid leaching solution in one pot, which comprises the steps of carrying out one-pot three-section reaction treatment on the leaching solution obtained by the serpentine normal-pressure sulfuric acid leaching, and then carrying out solid-liquid separation to obtain a purified magnesium solution; the one-pot three-section reaction process comprises the following steps: regulating pH of the leachate^A2.0-3.0, adding an oxidant to carry out first-stage oxidation treatment; subsequent control of the pH of the System^BAdding an oxidant to 4.5-6, and performing second-stage oxidation treatment; readjusting the pH of the System^CCarrying out a third stage of reaction after the reaction reaches 7-8 ℃; one-pot three-sectionIn the reaction process, the temperature of the first stage oxidation reaction and the second stage oxidation reaction is 60-80 ℃, and the temperature of the third stage oxidation reaction is 80-90 ℃. Under the one-pot three-section treatment process, the invention is matched with the joint control of the reaction type, the pH value and the temperature of each section, can realize the cooperation, can effectively separate magnesium and each ion with high selectivity in one pot, and is beneficial to obtaining high-purity magnesium solution.

Description

One-pot method for purifying magnesium from serpentine atmospheric sulfuric acid leaching solution

technical field

The invention relates to the field of comprehensive utilization of resources, in particular to a serpentine wet method for pure magnesium.

Background technique

Serpentine is a general term for hydrous magnesium-rich silicate minerals. Its chemical composition is 3MgO 2SiO ₂ 2H ₂ O. It is dark green, brown or yellow, and most of them have spots. It is named after the polished surface resembles a snake pattern. , hardness 2～3.5, density 2.2～3.69/cm ³ . Its crystal structure is composed of a layer of silicon-oxygen tetrahedron and a layer of magnesium hydroxide octahedron in a 1:1 combination to form a double-layer structure. Serpentine can be generally divided into three categories according to the mineral structure: (1) Chrysotile with a cylindrical structure; (2) Lizardite with a flat structure; (3) With an alternating wave shape Structure of leaf serpentine (Antigorite). All serpentine minerals, with or without fibrous features, are layered, similar to kaolinite. The Mg ²⁺ in the six-fold coordination in the ore can be replaced by A1 ³⁺ , Ni ²⁺ , Fe ²⁺ , Fe ³⁺ , Mn ²⁺ , etc., especially in aluminum serpentine (zoblitzite), nickel serpentine ( gamierite) and iron serpentine (greenallte), etc. are replaced. Usually serpentine contains a small amount of iron, aluminum, chromium, nickel, cobalt, manganese and other metals. Therefore, serpentine is an important potential resource of nickel and cobalt.

The hydrometallurgical smelting of serpentine is the main means of resource utilization. At present, the hydrochloric acid leaching process involved in the industry is mainly hydrochloric acid pickling process, high-pressure sulfuric acid pickling process, and atmospheric sulfuric acid pickling process. The hydrochloric acid acid leaching process has mild leaching conditions, small equipment investment, and the ^Cl- can effectively destroy colloidal stability, reduce solution viscosity, and facilitate operation and separation. requirements, which is not conducive to large-scale industrial applications. High-pressure sulfuric acid leaching process is often used in the smelting treatment of serpentine ore with high nickel grade, which can effectively control the leaching of iron, and is often used to extract nickel in serpentine; however, the high-temperature leaching process has high energy consumption and high cost. High requirements for ore grade. Compared with the high-pressure sulfuric acid leaching process, the atmospheric-pressure sulfuric acid leaching process is often used in the smelting of low-grade serpentine. It is difficult to separate the elements of the leachate obtained by the process, and SO ₄ ^2- is difficult to destroy the colloidal structure. It is easy to form gel during the leaching and purification and removal of impurities, which is difficult to operate, and the amount of slag produced during the removal of impurities is large, and the leachate contains SO ₄ ^{2 -Many} , the purification of valuable elements such as nickel and magnesium is difficult.

For the element recovery of low-grade sulfuric acid atmospheric leaching solution, the main method in the industry is to classify and recover in steps. For example, publication number CN103395796A discloses a comprehensive utilization method of serpentine. The steps are: after the serpentine is leached with sulfuric acid , filter to obtain the first filtrate; add an oxidant to the first filtrate; add a pH adjuster to produce a precipitation reaction, and then filter to obtain the iron-aluminum mixture and the second filtrate; add water and sodium hydroxide to the iron-aluminum mixture, and filter Obtain iron precipitate and sodium metaaluminate solution; add sulfide to the second filtrate for reaction, then filter to obtain nickel-cobalt mixture and the third filtrate; add oxidant to the third filtrate for reaction; add alkaline adsorbent, then filter Get magnesium sulfate solution, add ammonia water to prepare magnesium hydroxide.

For the smelting of low-grade serpentine sulfuric acid leaching solution at atmospheric pressure, most of the industry is classified and smelted by a multi-step separation process. This process has low treatment efficiency, poor process operability, and the recovery rate of target elements and product purity. needs improvement.

SUMMARY OF THE INVENTION

In view of the problems such as easy gel formation, high viscosity, unsatisfactory magnesium recovery rate and purity in the process of wet extraction of magnesium from serpentine atmospheric sulfuric acid leaching solution, the purpose of the present invention is to provide a serpentine atmospheric sulfuric acid leaching solution (the present invention also Referred to as leachate) one-pot method for purifying magnesium, aiming to provide a method for realizing selective separation of magnesium ions and other ions in leachate under one-pot system, and improving the recovery rate and purity of magnesium.

For the consideration of processing value, the low-grade serpentine is recovered by the sulfuric acid atmospheric acid leaching process. The leaching solution obtained by this process is a sulfuric acid system with high iron, high magnesium, low nickel and rich trace impurity elements. This type of leaching solution is difficult to achieve. The one-pot separation and recovery of magnesium mainly lies in: (1) the system is a high-iron sulfuric acid system, the solution is easy to form a colloid, and the sulfate ion is difficult to destroy the colloidal structure, which will affect the separation and recovery of magnesium and other components, and the technological operation is difficult , for example, it is difficult to filter; (2) in this system, there are abundant metal impurity components, and these components are difficult to achieve one-pot high-selectivity separation with magnesium; (3) the recovery rate, purity and whiteness of magnesium are not ideal. Aiming at the problem that the serpentine sulfuric acid atmospheric acid leaching solution is difficult to realize one-pot high-selectivity separation, the present invention provides the following improved process:

A method for purifying magnesium with a serpentine normal-pressure sulfuric acid leaching solution (also referred to as an acid leaching solution in the present invention) in one pot, the leaching solution of the serpentine sulfuric acid normal-pressure acid leaching is subjected to one-pot three-stage reaction treatment, followed by solid-liquid separation, to obtain a purified magnesium solution;

Fe, Cr, Mn and Mg are dissolved in the leaching solution;

The one-pot three-stage reaction process includes: adjusting the pH ^A of the leachate to be 2.0-3.0, adding an oxidant to carry out the first-stage oxidation treatment; then adjusting the pH ^B of the system to 4.5-6, adding an oxidant to carry out the second-stage oxidation treatment ; Carry out the third stage reaction after adjusting the pH ^C of the system to 7～8 again;

In the one-pot three-stage reaction process, the temperature of the first-stage oxidation reaction and the second-stage oxidation reaction is 60-80°C, and the temperature of the third-stage reaction is 80°C-90°C.

Aiming at the problems of difficulty in realizing one-pot purification of magnesium due to the characteristics of the components of the atmospheric sulfuric acid leaching solution and difficult process operation, the present invention innovatively proposes that under the one-pot three-stage treatment process, the reaction type, pH and The joint control of temperature can achieve synergy, and can solve the problem that the impurity elements and magnesium are difficult to be separated in one pot with high selectivity caused by the normal pressure acid leaching system, high iron, high impurity elements, and sulfuric acid system, and can effectively make magnesium and each ion one-pot. The high-selectivity separation of the pot is conducive to obtaining a high-purity magnesium solution. Not only that, the method of the present invention can also effectively improve the problem of poor processability (such as poor filterability) in the one-pot treatment process of the leachate, and can be enlarged by industrial practice.

According to the research of the present invention, the three-stage reaction process of the first-stage oxidation, the second-stage oxidation and the third-stage reaction under the one-pot system, and the joint control of the pH and temperature of each stage reaction are synergistic solutions to the normal pressure leachate. Difficult to deal with the problem in one pot, improve magnesium extraction and the key to purification.

In the present invention, the acid leaching solution is obtained by acid leaching of low-grade serpentine at atmospheric pressure with sulfuric acid.

In the present invention, the leaching solution is a sulfuric acid leaching solution of serpentine under normal pressure. The sulfuric acid concentration is, for example, 2-5 mol·L ^-1 . The temperature of the normal-pressure acid leaching is, for example, 80-100°C, preferably 80-95°C.

In the present invention, the leaching solution is a sulfuric acid system with high iron, low nickel and high magnesium. The concentrations thereof are, for example, the concentration of Fe is 5 to 18 g/L, the concentration of Mn(II) is 0.2 to 0.5 g/L, the concentration of Cr(III) is 0.10 to 0.40 g/L, and the concentration of Mg is 50 to 50 g/L. 65g/L. More preferably, the concentration of Fe is 6-12g/L; the concentration of Mn(II) is 0.12-0.4g/L, the concentration of Cr(III) is 0.20-0.4g/L, and the concentration of Mg is 50-65g/L . The technical solution of the present invention can show better industrial application value for the one-pot treatment of the leachate, but does not exclude the application of the method of the present invention to other leachates.

In the present invention, the acid leaching solution is also allowed to contain at least one of nickel, cobalt and aluminum; wherein, in the leaching solution, the concentration of Ni is 0.20-0.6g/L; the concentration of Co is 0.01-0.04g /L; the concentration of Al is 0.2-2 g/L; more preferably, the concentration of Ni is, for example, 0.30-0.6 g/L; the concentration of Co is, for example, 0.02-0.03 g/L; and the concentration of Al is 0.3-1.8 g/L . The technical scheme of the invention can realize the high selective separation of magnesium and iron, manganese, chromium, nickel, aluminum and cobalt in one pot in a sulfuric acid system, and has excellent magnesium smelting effect and efficiency.

In the present invention, in the one-pot three-stage treatment process, the pH of the system is adjusted by using an alkaline substance, such as at least one of magnesium oxide, alkali metal hydroxide, calcium oxide, and ammonia water. The alkaline substance can be added in the form of solid or solution.

In the present invention, in the one-pot three-stage treatment process, the oxidant is at least one of chlorate, oxygen or hydrogen peroxide.

In the present invention, an alkaline substance is added to the normal pressure leaching solution in advance, the pH of the system is adjusted to the required pH ^A , and an oxidant is introduced at the required temperature of 60°C to 80°C to carry out the first step in the one-pot reaction. Segment oxidation treatment. The research of the present invention finds that under the described temperature and pH, the nucleation behavior and morphology of iron can be regulated unexpectedly, and the separation and selection of magnesium, iron and other elements in one-pot system can be further improved unexpectedly. improved processing performance in one-pot treatments.

In the present invention, in the first stage of oxidation reaction, the amount of oxidant used is 1.2 to 1.5 times the theoretical molar amount for oxidizing Fe in the system. Preferably, pH ^A is 2.0 to 3.0. The temperature of the first-stage oxidation treatment is preferably 60 to 70°C, more preferably 60 to 65°C.

In the present invention, the time for the first-stage oxidation treatment is preferably 0.5 to 1.0 h.

In the present invention, after the first stage of oxidation treatment, without solid-liquid separation, the pH of the system is directly adjusted to pH ^B , and an oxidant is introduced at the required temperature of 60°C to 80°C to carry out the first step in the one-pot reaction. Secondary oxidation treatment. According to the research of the present invention, under the synergistic premise of the first-stage oxidation treatment and the joint control of the process and temperature of the second-stage oxidation treatment, the selective oxidation of Mn in the system can be realized, and the Cr in the system can be avoided. It can be combined with the first oxidation reaction to synergistically improve the one-pot separation selectivity of magnesium and other components, and improve the one-pot separation recovery rate and purity of magnesium.

Preferably, in the second stage of the oxidation reaction, the amount of the oxidant is 1.2 to 1.5 times the theoretical molar amount for oxidizing Mn in the system to Mn(IV) oxidation.

In the present invention, the temperature of the second-stage oxidation reaction process is preferably 60-70°C.

Preferably, pH ^B is 5.0-6.0.

Preferably, the time of the second-stage oxidation reaction is 0.5-1.0 h.

In the present invention, after the second-stage oxidation treatment, the solid-liquid separation is not carried out, the pH of the system is directly adjusted to pH ^C , and the third-stage reaction is carried out at the required temperature of 80°C to 90°C to realize the addition of magnesium. Selective precipitation of other ions such as Cr, and improved nucleation behavior, which can unexpectedly synergistically improve the separation of magnesium and other ions, improve magnesium recovery and purity, and improve the enrichment of other elements in the slag Effect.

Preferably, pH ^C is 7.0-8.0.

Preferably, the reaction time of the third stage is 2.0-3.0 h.

In the present invention, through the one-pot three-stage reaction, with the joint control of pH and temperature of each stage, synergy can be achieved, which is beneficial to control the nucleation behavior and morphology of elements in the one-pot system, and the The morphology of the slag constructed under the conditions can synergize with the subsequent conditions to induce the nucleation selectivity of other elements, which is beneficial to control the separation selectivity of Mg and other components, and is beneficial to improve the recovery rate and purity of magnesium. Reduce filtration difficulty and improve process operability.

In the present invention, the magnesium solution can be treated by known means. For example, adding a precipitant to a magnesium solution to carry out a magnesium precipitation reaction to produce magnesium hydroxide.

The precipitating agent is, for example, at least one of ammonia water and alkali metal hydroxide. The precipitant is in the form of a solution, and the concentration of the solution is, for example, 1 mol·L ^-1 to 13 mol·L ^-1 .

Preferably, the pH of the magnesium precipitation reaction process and the reaction end point is 8.8 to 9.5;

Preferably, the temperature of the magnesium precipitation reaction process is 70°C to 80°C;

Preferably, the reaction time of magnesium precipitation is 1-2h.

In the present invention, the magnesium hydroxide is placed in the alkaline solution for aging treatment, followed by solid-liquid separation, washing, and purified magnesium hydroxide;

Preferably, the alkali solution is an aqueous solution of alkali metal hydroxide, and the preferred concentration of the solute is 0.2 mol·L ^-1 to 0.5 mol·L ^-1 ;

Preferably, the aging temperature is 70°C to 80°C;

Preferably, the aging time is 60-120 min.

A preferred method for preparing high-purity magnesium hydroxide using leaching solution of the present invention, the method comprises the following steps:

(1) Add alkaline substances to the serpentine sulfuric acid leaching solution, and adjust the pH of the system to 2.0-3.0; then add an oxidant, and carry out the first-stage reaction at a temperature of 60-70 °C; then, without filtration, continue to add alkaline The pH of the system is adjusted to 4.5-6.0, and the oxidizing agent is added and the second-stage oxidation treatment is carried out at a temperature of 50-60 °C; no filtration is required after the treatment, and the pH of the system is 7.0-8.0 by adding an alkaline substance. The third-stage reaction is carried out at a temperature of 90° C.; then a pure magnesium sulfate solution can be obtained after one filtration.

(2) At a certain temperature, add a certain amount of precipitant to the magnesium sulfate solution obtained after filtration to carry out the magnesium precipitation reaction. The pH of the reaction process is controlled to be 8.8-9.5, the temperature is 70°C to 80°C, the time is 1-2 h, and then Mg(OH) ₂ is obtained by filtration. The method of adding the magnesium sulfate solution and the precipitant in the step (2) is bidirectional dropwise addition.

(3) Wash the magnesium hydroxide with hot water 3 to 5 times.

(4) adding a certain concentration of sodium hydroxide solution to magnesium hydroxide for reaction, filtering, washing, controlling the reaction temperature to be 70°C to 80°C, and the reaction time to be 60 to 120min, to obtain high-purity hydroxide that meets quality standards Magnesium products.

Compared with the prior art, the present invention has the following advantages and beneficial effects:

Aiming at the problems that the leaching solution of serpentine at atmospheric pressure sulfuric acid leaching is difficult to achieve one-pot purification of magnesium, and the process operation is difficult, the present invention innovatively proposes that under the one-pot three-stage treatment process, the reaction of each stage is coordinated. The joint control of type, pH and temperature can achieve synergy, and can solve the problem that magnesium and magnesium are difficult to separate with high selectivity in one pot caused by high iron and rich impurity elements in the normal pressure acid leaching system, and can effectively make magnesium and various ions high in one pot. Selective separation, utilizing to obtain high-purity magnesium solution, improves the recovery rate of magnesium and the enrichment recovery rate of other components in the slag, not only that, the method of the present invention can also effectively improve the poor processability (such as filtration) in the one-pot treatment process of the leachate. poor performance), using industrial practical amplification.

Description of drawings

Fig. 1 is the XRD pattern of embodiment 1 product;

Fig. 2 is the SEM image of the product of Example 1;

Detailed ways:

Below in conjunction with embodiment, the technical scheme of the present application is described in detail:

According to the chemical industry standard HG/T 3607-2007 for industrial magnesium hydroxide, industrial magnesium hydroxide can be divided into three categories:

Class I: Mainly used as a raw material for flame retardants, [Mg(OH) ₂ ] mass fraction/%≥97.5;

Class II: mainly used as raw materials for the production of magnesium oxide and magnesium salts; [Mg(OH) ₂ ] mass fraction/%≥93

Class III: Mainly used for flue desulfurization, wastewater treatment, agricultural fertilizers and soil conditioners, etc.; [Mg(OH) ₂ ] mass fraction/%≥92.

Therefore, the purity requirements of the Mg(OH) ₂ produced by the process of the invention meet the industry class I standard.

In the following cases, the acid leaching solution is obtained from low-grade serpentine by acid leaching with sulfuric acid at atmospheric pressure, and the main element concentration (g·L ^-1 ) in the serpentine normal pressure sulfuric acid leaching solution: Mg 60, Fe 12.89, Al 1.54, Cr(III) 0.33, Co(II) 0.025, Mn(II) 0.40, Ni(II) 0.55.

In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be described in further detail below in conjunction with the examples. limit.

Example 1:

Step (1): One-pot treatment:

The serpentine leaching solution (acid leaching solution) is 300mL. When the pH ^A of the leaching solution is adjusted to 2.0 with 10% MgO slurry, sodium chlorate with an iron content of 1.3 times is added, and the first stage of oxidation treatment is carried out at 60 °C for 30 minutes. Without filtration, continue to use 10% MgO slurry to adjust the pH ^B of the leachate to 5.5, introduce oxygen (1.3 times the molar amount of manganese), and carry out the second-stage oxidation treatment at 70 °C for 30 minutes; continue without filtration Adjust pH ^C to 7.0 with 10% MgO slurry, and conduct the third-stage reaction at 80°C for 2h;

After the one-pot three-stage treatment is completed, the filtration rate is 12 mg/min·cm ² . The content of nickel in the filtrate after filtration is 0.13 mg·L ^-1 , the content of cobalt is 0.07 mg·L ^-1 , and the content of manganese is 0.13 mg·L -1 . The content is 0.43mg·L ^-1 . Because the content of chromium and iron is extremely low, ICP has not detected it; the recovery rate of iron in the slag by this method is greater than 99.99%, the recovery rate of nickel is 99.97%, and the recovery rate of manganese is 99.87%. The recovery rate of chromium is greater than 99.99%, and the loss rate of magnesium is less than 0.7%.

Step (2): magnesium precipitation and aging:

The purified and impurity-removed solution was added dropwise with ammonia water to carry out precipitation reaction, the reaction temperature was 70°C, the pH of the reaction process and the reaction end point was 8.9; the reaction time was 1.0h, Mg(OH) 2 was obtained by filtration and washing, and washed to obtain Mg(OH) ₂ . The Mg(OH) ₂ was aged with 0.10 mol·L ^-1 NaOH (at a temperature of 70 °C) for 1.0 h. The sulfur content of magnesium hydroxide is 0.17%, the total recovery rate of magnesium is 80%, no Cr element is detected in magnesium hydroxide, the purity of magnesium hydroxide is 98.63%, and the whiteness is 98.6%. The XRD pattern and SEM pattern of magnesium hydroxide are shown in Figures 1 and 2.

Example 2:

Step (1): One-pot treatment:

Serpentine leaching solution (acid leaching solution, same as Example 1) was 300 mL, when the pH of the leaching solution was adjusted to 3 with 10% MgO slurry, sodium chlorate with 1.4 times of iron content was added, and the first stage oxidation treatment was carried out at 60° C. , oxidized for 40 minutes; when the pH of the leachate was adjusted to 6 with 10% MgO slurry, hydrogen peroxide with 1.4 times the manganese content was introduced, and the second stage oxidation treatment was carried out at 60 °C for 40 minutes; the pH was adjusted with 10% MgO slurry until the The pH was adjusted to 8, and the third-stage reaction was carried out at 90°C for 2H;

After the one-pot three-stage treatment is completed, the filtration rate is 15 mg/min·cm ² . The content of nickel in the filtrate after filtration is 0.074 mg·L ^-1 , the content of cobalt is 0.019 mg·L ^-1 , and the content of manganese is 0.074 mg·L -1 . The content is 1.48mg·L ^-1 , the content of chromium is 0.041mg·L ^-1 , the content of iron is 0.014mg·L ^-1 ; the recovery rate of iron in this method is more than 99.9%, the recovery rate of nickel is 99.92%, and the recovery rate of manganese is 99.92%. The recovery rate is 99.57%, the recovery rate of chromium is more than 99.99%, and the loss rate of magnesium is less than 0.8%

Step (2): magnesium precipitation and aging:

The solution after purification and removal of impurities was added with ammonia water, and the feeding temperature was controlled to be 30 ° C. After the pH of the system reached 9, the temperature was raised to 80 ° C, and the pH of the reaction process and the end point was controlled to be 9.2; Mg(OH) ₂ was obtained by washing, and the Mg(OH) ₂ obtained by washing was aged with 0.15mol·L ^-1 NaOH (temperature is 80°C) for 1.5h, the total recovery rate of magnesium was 82%, and the sulfur content of magnesium hydroxide Cr element was not detected in magnesium hydroxide, the purity of magnesium hydroxide was 98.71%, and the whiteness was 99.6%.

Example 3:

Step (1): One-pot treatment (pilot test treatment):

Serpentine leaching solution (acid leaching solution, same as Example 1) was 300L, when the pH of the leaching solution was adjusted to 2.5 with 10% MgO slurry, sodium chlorate with 1.5 times of iron content was added, and the first stage oxidation treatment was carried out at 65° C. , oxidized for 50 minutes; when the pH of the leachate was adjusted to 5 with 10% MgO slurry, oxygen with 1.5 times the manganese content was introduced, and the second-stage oxidation treatment was carried out at 65 °C for 50 minutes; continue to adjust pH with 10% MgO slurry until The pH was adjusted to 7.5, and the third-stage reaction was carried out at 85 °C for 2 h;

After the one-pot three-stage treatment is completed, the filtration rate is 73 g/h·dm ² . The content of nickel in the filtrate after filtration is 0.11 mg·L ^-1 , the content of cobalt is 0.09 mg·L ^-1 , and the content of manganese is 0.11 mg·L -1 . The content of iron was 0.41mg·L ^-1 , and the content of chromium was 0.85mg·L ^-1 . Due to the extremely low content of iron, ICP was not detected. The recovery of manganese was 99.89%, the recovery of chromium was 99.7%, and the loss of magnesium was 1.2%.

Step (2): magnesium precipitation and aging:

Step (1) Add ammonia water to the solution after purification and removal of impurities, control the feeding temperature to 40 ° C, when the pH of the system reaches 8.8, heat up to 75 ° C and keep the reaction, control the pH of the reaction process and the reaction end point to be 9.1, and the reaction time is 2.0h , and then filtered and washed to obtain Mg(OH) ₂ , and the obtained Mg(OH) ₂ was aged with 0.20 mol·L ^-1 NaOH (at a temperature of 75° C.) for 2.0 h. The total recovery rate of magnesium was 75%, and the hydrogen The sulfur content of the magnesium oxide was 0.16%, and no Cr element was detected in the magnesium hydroxide. The purity of the magnesium hydroxide was 98.5% and the whiteness was 99.3%.

Comparative Example 1:

Compared with Example 1, the only difference is that the temperature of the first stage oxidation process in the one-pot treatment process is 50°C; other operations and parameters are the same as those of Example 1.

The results are: in step (1), the filtration efficiency is 6 mg/min·cm ² ; the recovery rate of iron is 80%, the recovery rate of nickel is 95%, the recovery rate of manganese is 96%; the recovery rate of chromium is 94% The loss rate of magnesium is 10%; in step (2), the total recovery yield of magnesium hydroxide is 70%, the purity is 98.5%, and the whiteness is 98.6%; Cr element in the magnesium hydroxide is 0.0334%, and the sulfur content is 0.0334%. is 0.2%. The filtering performance and product quality of the process, such as purity and whiteness, are not as good as those of Example 1.

Comparative Example 2:

Compared with Example 1, the only difference is that the temperature of the second-stage oxidation treatment process in the one-pot treatment process is 50°C; other operations and parameters are the same as those of Example 1.

The results are: in step (1), the recovery rate of iron is 98.8%, the recovery rate of nickel is 97.5%, the recovery rate of manganese is 70%, and the recovery rate of chromium is 94%; the loss rate of magnesium is less than 0.8%; In step (2), the total yield of magnesium is 79%, the purity is 96.8%, and the whiteness is 89%; the sulfur content is 0.18%, and the Cr element is 0.0771%.

Comparative Example 3:

Compared with Example 1, the only difference is that the oxidation treatment of the second stage in the one-pot treatment process is 90°C; other operations and parameters are the same as those of Example 1.

The results are: in step (1), the recovery rate of iron is 97.7%, the recovery rate of nickel is 98%, and the recovery rate of manganese is 96%; the recovery rate of chromium is 80%, and the loss rate of magnesium is less than 0.8%; In step (2), the total yield of magnesium is 76%, the purity is 95.4%, and the whiteness is 87%; the sulfur content in the magnesium hydroxide is 0.21%, and the Cr element is 0.0419%.

Comparative Example 4:

Compared with Example 1, the only difference is that the third stage of the one-pot treatment process is treated at 60°C; other operations and parameters are the same as those of Example 1.

The results are: in step (1), the recovery rate of iron is 97%, the recovery rate of nickel is 96.4%, the recovery rate of manganese is 94%, the recovery rate of chromium is 95%, and the loss rate of magnesium is 3%; In (2), the total yield of magnesium is 77%, the purity is 97.5%, and the whiteness is 98%; the sulfur content in magnesium hydroxide is 0.18%.

Comparative Example 5:

Compared with Example 1, the only difference is that in the one-pot second stage process of step (1), pH ^B is 4.0. Other parameters are the same as in Example 1.

The results were: in step (1), the recovery rate of iron was 98%, the recovery rate of nickel was 97%, the recovery rate of manganese was 73%, the recovery rate of chromium was 94%, and the loss rate of magnesium was 1%.

In step (2), the total recovery rate of magnesium is 80%, the sulfur content of magnesium hydroxide is 0.2%, the purity of magnesium hydroxide is 96.4%, and the whiteness is 87%.

Comparative Example 6:

Compared with Example 1, the only difference is that in the one-pot second stage process of step (1), pH ^B is 6.5.

The results are: in step (1), the recovery rate of iron is 96%, the recovery rate of nickel is 97%, the recovery rate of chromium is 82%, the recovery rate of manganese is 96%, and the loss rate of magnesium is 0.9%.

In step (2), the total recovery rate of magnesium is 78%; the purity of magnesium hydroxide is 95.1%, the sulfur content is 0.23%, and the whiteness is 88%.

Claims (10)

1. the method for purifying magnesium in one pot of serpentine normal pressure sulfuric acid leachate, it is characterized in that, the leachate of serpentine sulfuric acid normal pressure acid leaching is carried out one pot three-stage reaction processing, subsequently solid-liquid separation, obtains the magnesium solution of purification; Fe, Mn, Cr and Mg are dissolved in the leaching solution; The one-pot three-stage reaction process includes: adjusting the pH ^A of the leachate to be 2.0-3.0, adding an oxidant to carry out the first-stage oxidation treatment; then adjusting the pH ^B of the system to 4.5-6, adding an oxidant to carry out the second-stage oxidation treatment ; Carry out the third stage reaction after adjusting the pH ^C of the system to 7～8 again; In the one-pot three-stage reaction process, the temperature of the first-stage oxidation reaction and the second-stage oxidation reaction is 60-80°C, and the temperature of the third-stage reaction is 80°C-90°C. 2. the method for one-pot purifying magnesium of serpentine atmospheric sulfuric acid leaching solution as claimed in claim 1, it is characterized in that, the sulfuric acid concentration of normal pressure sulfuric acid leaching process is 2～5mol L ^-1 ; The temperature of acid leaching process It is 80～100 ℃. 3. the method for purifying magnesium in one pot of serpentine atmospheric sulfuric acid leachate as claimed in claim 1, is characterized in that, in described leachate, the concentration of Fe is 5～18g/L; The concentration of Mn is 0.2～0.5 The concentration of g/L and Cr is 0.10 to 0.40 g/L, and the concentration of Mg is 50 to 65 g/L. 4. the method for one-pot purifying magnesium of serpentine atmospheric sulfuric acid leaching solution as claimed in claim 1, is characterized in that, in acid leaching solution, also contains at least one in nickel, cobalt, aluminum; Preferably, in the leaching solution, the concentration of Ni is 0.20-0.6 g/L; the concentration of Co is 0.01-0.04 g/L; the concentration of Al is 0.2-2 g/L. 5. the method for one-pot purifying magnesium of serpentine atmospheric sulfuric acid leachate as claimed in claim 1, is characterized in that, in one-pot three-stage treatment process, adopts the pH of alkaline substance control system, described alkaline substance It is at least one of magnesium oxide, calcium oxide, alkali metal hydroxide and ammonia water. 6. the method for one-pot purifying magnesium of serpentine atmospheric sulfuric acid leachate as claimed in claim 1, is characterized in that, in one-pot three-stage treatment process, oxidant is at least one of chlorate, oxygen, hydrogen peroxide kind. 7. the method for one-pot purifying magnesium of serpentine atmospheric sulfuric acid leachate as claimed in claim 1, is characterized in that, the first stage oxidation reaction stage, the consumption of oxidant is by Fe in the system The theoretical ^molar weight of oxidation 1.2 to 1.5 times of ; Preferably, in the second stage of oxidation reaction, the dosage of the oxidant is 1.2-1.5 times the theoretical molar amount for oxidizing Mn(II) in the system to Mn(IV) oxidation. 8. the method for one-pot magnesium purification of serpentine atmospheric sulfuric acid leaching solution as claimed in claim 1, is characterized in that, the time of first-stage oxidation reaction is 0.5～1h; Preferably, the time of the second-stage oxidation reaction is 0.5-1 h; Preferably, the reaction time of the third stage is 2.0-3.0 h. 9. the method for one-pot purifying magnesium of serpentine atmospheric sulfuric acid leachate as claimed in claim 1, is characterized in that, in magnesium solution, add precipitating agent, carry out magnesium precipitation reaction, make magnesium hydroxide; Preferably, the pH of the magnesium precipitation reaction process and the end point is 8.8 to 9.5; Preferably, the temperature of the magnesium precipitation reaction process is 70°C to 80°C; Preferably, the reaction time of magnesium precipitation is 1-2h. 10. the method for one-pot purifying magnesium of serpentine atmospheric sulfuric acid leaching solution as claimed in claim 9, is characterized in that, magnesium hydroxide is placed in lye to carry out ageing treatment, subsequently solid-liquid separation, washing, making Purified magnesium hydroxide; Preferably, the alkali solution is an aqueous solution of alkali metal hydroxide, and the preferred concentration of the solute is 0.2 mol·L ^-1 to 0.5 mol·L ^-1 ; Preferably, the aging temperature is 70°C to 80°C; Preferably, the aging time is 60-120 min.

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