Iron removal process and application

Abstract

The invention discloses an iron removal process and application, and belongs to the field of non-ferrous metal hydrometallurgy. The process comprises the following steps: reducing Fe < 3 + > in an iron-containing solution into Fe < 2 + > to obtain a reduced iron-containing solution; after the pH of the reduced iron-containing solution is adjusted, an oxidizing agent is added to maintain the concentration of Fe < 3 + > to be 2.0-8.2 g / L, then sulfate is added, an iron removal reaction with the ihleite method is carried out, and after solid-liquid separation is carried out, iron vitriol slag and first iron-removed liquid are obtained; according to the method, the forming rate of the jarosite slag can be controlled, and the loss rate of valuable metal can be reduced. A goethite method and a hydrothermal method are further combined for iron removal, the iron removal efficiency is high, and the loss rate of valuable metal is low.

Description

Technical Field

[0001] The invention relates to the field of nonferrous metal hydrometallurgy, and in particular to an iron removal process and application thereof. Background Art

[0002] At present, there are many ways to remove iron in rare earth hydrometallurgy, mainly including neutralization hydrolysis method, pyrite method, goethite method and hematite method.

[0003] Among them, the iron content in the liquid after iron removal by the pyrite method or the goethite method does not meet the requirements of deep iron removal, increasing the cost of subsequent recovery of valuable metals; the hematite method needs to be carried out under high temperature and high pressure conditions, and the equipment is expensive and the maintenance cost is high, making it difficult to achieve industrial production; the simple use of the hydrolysis method will cause a high content of other metal ions in the slag, and the effective recovery of valuable metals cannot be achieved; the neutralization hydrolysis method of iron will generate Fe(OH)3 colloidal precipitate, which will make filtration difficult, and the precipitate contains a high content of valuable metals, which cannot achieve effective recovery of valuable metals.

[0004] In view of this, the present invention is proposed. Summary of the invention

[0005] The purpose of the present invention includes providing an iron removal process and application, and providing a recovery process with high iron removal rate and low valuable metal loss rate.

[0006] In order to achieve the above object, the present invention provides an iron removal process in a first aspect, comprising:

[0007] The Fe in the iron-containing solution 3+ Reducing agent to Fe 2+ , obtaining a reduced iron-containing solution;

[0008] After adjusting the pH of the reduced iron-containing solution, an oxidant is added to maintain the Fe 3+ The concentration is 2.0-8.2 g / L, and then sulfate is added to carry out the ferroalloy method to remove iron. After solid-liquid separation, ferroalloy slag and the first deironing liquid are obtained.

[0009] In some embodiments, the reducing agent includes at least one of SO2, sodium sulfite, ammonium sulfite and iron powder;

[0010] and / or, adjusting the pH of the reduced iron-containing solution to 1.0-1.5;

[0011] and / or, the oxidant comprises at least one of H2O2, sodium hypochlorite, potassium permanganate and sodium chlorate;

[0012] And / or, the sulfate includes at least one of sodium sulfate, ammonium sulfate and potassium sulfate.

[0013] In some embodiments, the temperature of the iron removal reaction by the jacinth method is 75-105° C., and a neutralizing agent is added to maintain the pH of the reaction solution at 1.0-2.5.

[0014] In some embodiments, the first iron-removed liquid is subjected to a goethite method to remove iron, thereby obtaining a second iron-removed liquid and goethite;

[0015] The second deironed liquid is deironed by a hydrothermal method to obtain a pure liquid and goethite.

[0016] In some embodiments, the goethite method for iron removal includes adding the first iron removal solution to an acid solution with a pH value of 2.0-3.5 to make Fe 3+ The concentration is 1.0-2.0g / L, and a neutralizer is added to maintain the pH of the solution at 2.0-3.5 during the reaction process, and the reaction temperature is maintained at 50-70°C.

[0017] In some embodiments, the hydrothermal iron removal includes adding alkali to the second iron-removed liquid to carry out a precipitation reaction, then adding an acid to adjust the pH of the reaction solution to 3.0-4.0 and carrying out a hydrothermal reaction, and separating the solid and liquid to obtain the goethite and the pure liquid; wherein the hydrothermal reaction temperature is 100-200°C and the pressure is 0.1-10MPa.

[0018] In some embodiments, the iron alum residue is roasted, washed, dried, ground, and sieved to obtain iron oxide red powder.

[0019] In some embodiments, the calcination temperature is 450-550°C, and the calcination time is 2-3h;

[0020] The water washing includes primary water washing and secondary water washing; the primary water washing has a solid-liquid mass ratio of 2-4:1, a temperature of 60-70°C, and a stirring time of 1-2h; the secondary water washing has a solid-liquid mass ratio of 3-5:1, a temperature of 50-70°C, and a stirring time of 0.5-1.2h.

[0021] In some embodiments, the neutralizing agent is at least one of sodium carbonate, ammonium carbonate, potassium carbonate, ammonium bicarbonate and sodium bicarbonate.

[0022] The second aspect of the present invention also provides application of the iron removal process of the first aspect in recycling waste lithium-ion batteries.

[0023] The beneficial effects of the present invention include:

[0024] The present invention provides an iron removal process and application, wherein the iron removal process removes Fe 3+ Reduction to Fe 2 + , and then by controlling the degree of oxidation, Fe3+ The concentration is maintained at an appropriate level, thereby controlling the formation rate of iron alum slag, which is beneficial to improving the purity of the iron alum slag and reducing the loss rate of valuable metals. The present invention further combines the goethite method and the hydrothermal method for iron removal, further improving the iron removal rate while reducing the loss of valuable metals. Among them, the iron alum method is used for iron removal without introducing new impurities, reducing the difficulty and cost of subsequent impurity removal and improving the comprehensive recovery efficiency; the goethite method is used to remove iron to reduce the Fe in the second iron removal liquid 3+ The concentration of goethite is crystalline and has good filtration performance. Finally, the Fe content in the pure liquid is reduced by hydrothermal iron removal. 3+ At the same time, the iron alum slag is roasted, washed and other processes to obtain iron red powder, which improves the utilization rate of iron and increases economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0026] Figure 1 A process flow chart of the iron removal process provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0027] Below, a detailed description of an iron removal process and application of the present invention is specifically disclosed with appropriate reference to the accompanying drawings. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters and repeated descriptions of actually the same structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following descriptions are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0028] The "range" disclosed in the present application is defined in the form of a lower limit and an upper limit, and a given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundaries of the particular range. In particular, "(", ")", "[" and "]" represent intervals, wherein "(" or ")" represents an open interval, i.e., the endpoint values ​​of the interval are not included; "[" and "]" represent a closed interval, i.e., the endpoints within the interval are included. The range defined in this way may be inclusive or exclusive of the end values, and may be arbitrarily combined, i.e., any lower limit may be combined with any upper limit to form a range.

[0029] Specifically, for example, if a range of 60-120 and 80-110 is listed for a particular parameter, it is understood that the range of 60-110 and 80-120 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3, 4 and 5 are listed, the following ranges can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In this application, unless otherwise specified, the numerical range "ab" represents an abbreviation of any real number combination between a and b, where a and b are both real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" have been fully listed in this article, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a certain parameter is expressed as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc. If (10, 20) is listed, it is understood as any value between 10 and 20, excluding 10 and 20; (10, 20] is understood as any value between 10 and 20, excluding 10 but including 20.

[0030] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0031] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0032] If there is no special explanation, all steps of the present application can be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0033] If there is no special explanation, the "include" and "comprising" mentioned in this application are open-ended or closed-ended. For example, the "include" and "comprising" may mean that other components not listed may also be included or only the listed components may be included or only the listed components may be included.

[0034] If not specifically stated, in this application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0035] A first aspect of the present invention provides an iron removal process, comprising:

[0036] The Fe in the iron-containing solution 3+ Reducing agent to Fe 2+ , obtaining a reduced iron-containing solution;

[0037] After adjusting the pH of the reduced iron-containing solution, the speed at which the oxidant is added to the reduced iron-containing solution is controlled to maintain the Fe 3+ The concentration is 2.0-8.2 g / L, and sulfate is added to carry out iron alum method iron removal reaction. After solid-liquid separation, iron alum slag and the first iron removal liquid are obtained.

[0038] In some embodiments, the reducing agent includes at least one of SO2, sodium sulfite, ammonium sulfite and iron powder. The trivalent iron in the solution is completely reduced to divalent iron, and the amount of Fe in the iron alum method iron removal reaction is further regulated by adjusting the amount of the oxidant entering. 3+ The concentration is 2.0-8.2g / L, Fe 3+ When the concentration is too high, part of the trivalent iron will form iron hydroxide precipitation, which will absorb the valuable metals in the solution; Fe 3+ The concentration of iron alum is too low, which reduces the formation rate of iron alum slag. The selected reducing agent will not introduce new impurity ions into the solution. The present invention controls the Fe 3+ The concentration can control the precipitation rate of iron alum slag and reduce the loss rate of valuable metals.

[0039] In some embodiments, after adjusting the pH of the reduced iron-containing solution to 1.0-1.5, an oxidant is added. If the pH value of the solution before oxidation is too low, the alum formation rate will be slowed down, the reaction time will be too long, and the iron removal efficiency will be low. If the pH value of the solution before oxidation is too high, a large amount of colloidal iron hydroxide will be generated, which will absorb more valuable metals, affect the purity of the iron alum, and cause the loss of valuable metals.

[0040] In some embodiments, the oxidant includes at least one of H2O2, sodium hypochlorite, potassium permanganate and sodium chlorate. Specifically, when the oxidant is H2O2, the flow rate of H2O2 addition is 0.6-2.5 mL / min, so that Fe 3+ The concentration is 2.0-8.2g / L. Too high a flow rate will cause Fe3+ Too high a concentration and too low a flow rate will result in Fe 3 + If the concentration is too low, the iron removal effect will be affected.

[0041] In some embodiments, the sulfate includes at least one of sodium sulfate, potassium sulfate, and ammonium sulfate. If there are not enough alkali metal cations or ammonium ions in the solution, Fe 3+ It is possible to react with hydrogen ions or hydronium ions (H3O + ) produces ferrocyanide, which has poor sedimentation performance, filtration and washing effects, and will cause the residual iron in the solution to remain high.

[0042] In some embodiments, during the iron removal process using the jacinthite method, the concentration of alkali metal cations or ammonium ions in the reaction is maintained at 3-7 g / L.

[0043] In some embodiments, the first iron-removed liquid is subjected to a goethite method to remove iron, thereby obtaining a second iron-removed liquid and goethite;

[0044] The second deironed liquid is deironed by a hydrothermal method to obtain a pure liquid and goethite.

[0045] The present invention adopts three methods in combination to remove iron from the iron-containing solution, and the iron content in the obtained second iron-removed solution is greatly reduced. The iron-containing slag obtained by the three methods has high purity and can be reused through simple post-treatment. The reason why the present invention adopts the sequence of yttrium method-goethite method-hydrothermal method is that the higher Fe 3+ If the concentration of iron-containing solution is directly removed by the goethite method, a large amount of iron hydroxide colloid will be formed, which will adsorb more valuable metals and cause the loss of valuable metals. 3+ concentration, will lead to low iron removal efficiency; at higher Fe 3+ Concentrated iron-containing solution, ferroalloy removal can form ferroalloy slag, which has large particles and is easy to filter out; in the hydrothermal method, the trivalent iron ions are first reacted to form an iron hydroxide intermediate, and then acid is added for adjustment. Under the action of hydrothermal dehydration, goethite is generated. If the solution contains Fe 3+ If the concentration is too high, basic iron sulfate and hydrated ferrocyanide will be produced during the hydrothermal process to form goethite, which is not conducive to the application of iron red powder formed by subsequent goethite treatment in iron smelting and inorganic pigments. 3+ Concentrated iron-containing solution, and then the goethite method is used to treat the lower Fe 3+ The first iron removal liquid with high concentration is finally treated with hydrothermal method to treat low Fe 3+ Concentration of the second iron removal liquid.

[0046] In some embodiments, the goethite method for iron removal includes adding the first iron removal solution to an acid solution with a pH value of 2.0-3.5 to make Fe 3+ The concentration is 1.0-2.0 g / L, and a neutralizer is added to maintain the pH of the reaction process at 2.0-3.5. The reaction temperature of the goethite method for iron removal is 50-70°C.

[0047] In some embodiments, the first iron-removed liquid is added to the acid solution at a rate of 1.6-3.5 m / s. 3 / h, making Fe 3+ The concentration is stabilized at 1.0-2.0 g / L to ensure that the iron removal by the goethite method proceeds smoothly without producing amorphous iron hydroxide colloid.

[0048] In some embodiments, the hydrothermal deironing includes adding alkali to the second deironing liquid for precipitation reaction, then adding acid to adjust the pH of the reaction solution to 3.0-4.0 and performing a hydrothermal reaction to obtain the goethite and the pure liquid; wherein the hydrothermal reaction temperature is 100-200°C and the pressure is 0.1-10MPa. First, add alkali to the second deironing liquid for precipitation reaction and then add acid to make the pH value of the reaction solution 3.0-4.0, and perform hydrothermal deironing at this pH value. After hydrothermal deironing, almost all the residual iron in the solution is precipitated, and the iron slag has a crystalline structure and good filtration performance, which can be used as an ironmaking raw material after treatment.

[0049] In some embodiments, the neutralizing agent is at least one of sodium carbonate, ammonium carbonate, potassium carbonate, ammonium bicarbonate and sodium bicarbonate. On the one hand, it can supplement the monovalent cations required in the solution, and at the same time achieve the purpose of adjusting the pH of the solution, without introducing new impurities, and reducing the difficulty and cost of subsequent impurity removal.

[0050] In some embodiments, the iron alum residue is roasted, washed, dried, ground, and sieved to obtain iron red powder. The washing process includes a primary washing and a secondary washing, and the soluble salt (such as sodium sulfate) in the roasted residue is dissolved in water and reused in the iron-containing solution. The obtained iron red powder can be subsequently used for iron smelting or as an inorganic pigment.

[0051] In some embodiments, the iron removal process is applied to the recycling of waste lithium-ion batteries. For example, it is applied to the recycling of ternary lithium-ion batteries. In the recycling process of ternary lithium-ion batteries, after the rough treatment to remove iron and aluminum, the method provided by the present invention is used to further remove iron from the mixed solution, and the valuable metal elements nickel, cobalt and manganese are recovered at the same time.

[0052] Hereinafter, the embodiments of the present application will be described. The embodiments described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. If no specific techniques or conditions are indicated in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. If the manufacturer is not indicated in the reagents or instruments used, they are all conventional products that can be obtained commercially.

[0053] Please refer to the process flow chart Figure 1 The features and performance of the present invention are further described in detail below in conjunction with the examples. It should be understood that these examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

[0054] Example 1

[0055] (1) Iron ion reduction

[0056] Take 500ml of iron-containing solution into the reactor. The ion concentrations of nickel, cobalt, manganese and iron in the iron-containing solution are 24.69g / L, 30.28g / L, 28.6g / L and 25.24g / L respectively. Open the air inlet valve at the bottom of the reactor and introduce SO2 gas. Control the temperature in the reactor at 85-95℃ during the reaction process until Fe 3+ Reduction to Fe 2+ .

[0057] (2) Iron removal by ferroaluminate method

[0058] Add concentrated sulfuric acid to adjust the pH value of the solution to 1.0-1.5. After the pH of the solution stabilizes, add H2O2 to control the flow rate at 1.2-1.9 mL / min and detect Fe in the solution. 3+ The concentration is 4-6.3 g / L, saturated sodium sulfate solution is added to a concentration of 4-6 g / L, and a 10% sodium carbonate solution is slowly added during the reaction to maintain the pH value of the solution at 1.5-2.0. After reacting for 2 hours, the solution is filtered to obtain yellow sodium ferroaluminate and the first iron-removed liquid.

[0059] (3) Iron removal by goethite method

[0060] First, prepare a sulfuric acid solution with a pH value of 2.5-3.0 and add it to the reactor. Then slowly and evenly add the first iron-removing liquid to the reaction bottom liquid. Control the feeding rate of the first iron-removing liquid to make Fe 3+ The concentration is 1.0-2.0g / L, and the feed rate is 1.6-3.5m 3 / h, control the reaction temperature to 60°C, add saturated sodium carbonate solution to maintain the pH value of the solution at 2.5-3.0 during the reaction process, react for 60 minutes, separate the solid and liquid, and obtain goethite and the second iron-removed liquid.

[0061] (4) Hydrothermal iron removal

[0062] The second deironing liquid was transferred to a reactor, sodium hydroxide solution was added to generate a colloidal iron hydroxide precursor until no more precipitation was generated, dilute sulfuric acid was slowly added to adjust the pH value to 3.0-4.0, and then transferred to a hydrothermal reactor for a 60-min hydrothermal reaction (temperature of 150°C, pressure of 2.0MPa). After solid-liquid separation, goethite and pure liquid were obtained.

[0063] (5) Treatment of iron alum slag

[0064] The yellow sodium ferroalum obtained in the yellow ferroalum method is roasted at 500℃ for 2h to obtain roasted slag, and the roasting produces sulfur trioxide for preparing sodium sulfate. The obtained roasted slag is washed and stirred twice to obtain washed slag, wherein the solid-liquid mass ratio of the first washing is 3:1, and it is stirred at 65℃ for 1h; the solid-liquid mass ratio of the second washing is 4:1, and it is stirred at 60℃ for 0.8h. The washed slag is dried, ground, and sieved to obtain iron red powder.

[0065] The difference between the preparation methods of Examples 2-7 and Comparative Examples 1-6 and the iron removal process of Example 1 is only the difference in technical parameters in the iron removal process of step (2) the ferroaluminate method, as shown in Table 1.

[0066] Table 1 Parameters and results of iron removal by ferroaluminate method

[0067]

[0068] It can be seen from Table 1 that the Fe 3+ The concentration of Fe 3+ Compared with the iron removal process provided in Example 1 of the present invention, the H2O2 feed flow rate in Comparative Example 1 is too high, which will cause Fe 3+ The concentration of Fe is too high, and the local Fe 3+ The formation of iron hydroxide colloid slows down the filtration speed of the feed liquid and increases the nickel content in the iron alum slag. Similarly, in Example 2, the H2O2 feed rate is too low, which will cause Fe 3+ The concentration is too low and the reaction rate is too slow, resulting in low efficiency of the process.

[0069] By controlling the amount of sodium carbonate added during the iron removal reaction by the jasper alum method, the pH value of the reaction is controlled. Compared with the iron removal method provided by the present invention, the pH value in Comparative Example 3 is too low, which affects the yield of jasper alum and reduces the efficiency of the process; the pH value in Comparative Example 4 is too high, which makes Fe 3+ Hydrolysis forms iron hydroxide colloid, which slows down the filtration rate of the feed solution, increases the nickel content in the iron alum residue, and increases the loss rate of valuable metal ions in the recovery system.

[0070] Compared with the iron removal method provided by the present invention, the reaction temperature of the iron alum method iron removal process in Comparative Example 5 is reduced, resulting in a slower generation rate of sodium ferroalum, thereby reducing the efficiency of the process flow; the reaction temperature of the iron alum method iron removal process in Comparative Example 6 is increased, and the iron ion concentration in the liquid after the first iron removal is reduced, but the nickel content in the ferroalum slag is greatly increased, which increases the loss rate of valuable metal ions in the recovery system.

[0071] The preparation method of Comparative Examples 7-8 is different from the iron removal process of Example 1 only in the difference in technical parameters during the treatment of iron alum slag in step (5), as shown in Table 2.

[0072] Table 2 Parameter settings and results of iron alum slag treatment

[0073]

[0074] It can be seen from Table 2 that when the iron alum slag is roasted at a temperature of 500°C, the sodium sulfate in the slag will not decompose, so it can be effectively recovered after further water washing. Compared with the comparative example 7 without water washing and the comparative example 8 with one water washing, the iron removal method provided by the present invention can significantly reduce the sodium content in the water-washed slag after two water washings, enrich and recycle the soluble sodium salt, and improve the purity of the water-washed slag, which is beneficial to subsequent utilization.

[0075] The preparation methods of Examples 8-11 and Comparative Examples 9-12 differ from the iron removal process of Example 1 only in the difference in technical parameters in the iron removal process of the goethite method in step (3), as shown in Table 3.

[0076] Table 3 Goethite method iron removal parameter settings and results

[0077]

[0078] It can be seen from Table 3 that the Fe content in the second iron removal liquid obtained by the goethite method under different pH conditions is 3+ The concentration is different from the content of nickel and cobalt in goethite. It can be seen from Comparative Example 9 that in a pH range lower than that provided by the present invention, the Fe 3+ The concentration is high and iron cannot be effectively removed; it can be seen from Comparative Example 10 that in a pH range higher than that provided by the present invention, the content of nickel and cobalt in goethite increases, resulting in the loss of nickel and cobalt.

[0079] Fe in the second deironing liquid obtained by goethite method at different reaction temperatures 3+ From Comparative Example 11, it can be seen that the reaction temperature of the iron removal process by goethite is lower than the temperature range provided by the present invention, which will result in the liquid Fe 3+The concentration is high and the iron cannot be removed effectively. As can be seen from Comparative Example 12, the reaction temperature of the iron removal process by the goethite method is higher than the temperature range provided by the present invention, which makes Fe 3+ The hydrolysis rate increases, the pH value of the solution decreases rapidly, and the pH value during this period is difficult to control, resulting in increased costs. At the same time, the nickel and cobalt content in goethite increases, resulting in the loss of nickel and cobalt.

[0080] Compared with the iron removal process of Comparative Example 13 and Example 1, the only difference lies in the difference in technical parameters during the hydrothermal iron removal process in step (4), as shown in Table 4.

[0081] Table 4 Hydrothermal iron removal parameter settings and results

[0082] parameter Second iron removal liquid treatment method <![CDATA[Fe in the third iron-removed liquid (pure liquid) 3+ , g / L]]> Example 1 Hydrothermal iron removal 0.004 Comparative Example 13 none 0.036

[0083] It can be seen from Table 4 that, compared with Comparative Example 13, in the deironing method provided by the present invention, the iron content in the second deironing liquid is greatly reduced after deironing by hydrothermal method.

[0084] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and the embodiments having the same structure as the technical idea and exerting the same effect within the scope of the technical solution of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the main purpose of the present application, various modifications that can be thought of by those skilled in the art to the embodiments and other methods of combining some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A process for removing iron, It is characterized in that The following steps are involved: The Fe in the iron-containing solution 3+ Reducing agent to Fe 2+ , obtaining a reduced iron-containing solution; After adjusting the pH of the reduced iron-containing solution, an oxidant is added to maintain the Fe 3+ The concentration is 2.0-8.2 g / L, and then sulfate is added to carry out the ferroalloy method to remove iron. After solid-liquid separation, ferroalloy slag and the first deironing liquid are obtained.

2. The iron removal process according to claim 1, It is characterized in that The reducing agent includes at least one of SO2, sodium sulfite, ammonium sulfite and iron powder; and / or, adjusting the pH of the reduced iron-containing solution to 1.0-1.5; And / or, the oxidant comprises H 2 O 2 , sodium hypochlorite, potassium permanganate and sodium chlorate; And / or, the sulfate includes at least one of sodium sulfate, ammonium sulfate and potassium sulfate.

3. The iron removal process according to claim 1, It is characterized in that The temperature of the iron removal reaction by the jacinth method is 75-105° C., and a neutralizing agent is added to maintain the pH of the reaction solution at 1.0-2.

5.

4. The iron removal process according to claim 1, It is characterized in that The first deironed liquid is deironed by a goethite method to obtain a second deironed liquid and goethite; The second deironed liquid is deironed by a hydrothermal method to obtain a pure liquid and goethite.

5. The iron removal process according to claim 4, It is characterized in that The goethite method for removing iron comprises adding the first iron removal solution to an acid solution with a pH value of 2.0-3.5 to make Fe 3+ The concentration is 1.0-2.0g / L, and a neutralizer is added to maintain the pH of the solution at 2.0-3.5 during the reaction process, and the reaction temperature is maintained at 50-70°C.

6. The iron removal process according to claim 4, It is characterized in that The hydrothermal deironing comprises adding alkali to the second deironing liquid for precipitation reaction, then adding acid to adjust the pH of the reaction solution to 3.0-4.0 and performing hydrothermal reaction, solid-liquid separation, to obtain the goethite and the pure liquid; wherein the hydrothermal reaction temperature is 100-200°C and the pressure is 0.1-10MPa.

7. The iron removal process according to claim 1, It is characterized in that The iron alum residue is roasted, washed, dried, ground and sieved to obtain iron red powder.

8. The iron removal process according to claim 7, It is characterized in that The calcination temperature is 450-550°C, and the calcination time is 2-3h; The water washing includes primary water washing and secondary water washing; the primary water washing has a solid-liquid mass ratio of 2-4:1, a temperature of 60-70°C, and a stirring time of 1-2h; the secondary water washing has a solid-liquid mass ratio of 3-5:1, a temperature of 50-70°C, and a stirring time of 0.5-1.2h.

9. The iron removal process according to any one of claims 3 or 5, It is characterized in that The neutralizing agent is at least one of sodium carbonate, ammonium carbonate, potassium carbonate, ammonium bicarbonate and sodium bicarbonate.

10. Application of the iron removal process according to any one of claims 1 to 9 in the recycling of waste lithium-ion batteries.

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