A method for removing heavy metal ion impurities from a solution containing iron salts and an apparatus therefor

Abstract

The application discloses a method for removing heavy metal ion impurities in a solution containing iron salts, and comprises the following steps: step one: oxidizing a solution containing iron salts to be treated by adding an oxidizing agent and / or an electrochemical method to obtain an acidic solution containing iron A; or, after oxidizing the solution containing iron salts to be treated by adding an oxidizing agent and / or an electrochemical method, reducing the solution by adding a reducing agent and / or an electrochemical method to obtain the acidic solution containing iron A; the redox potential of the acidic solution containing iron A is 100-700 mV; step two: adding oxalic acid and / or oxalate to the acidic solution containing iron A to generate a precipitate of heavy metal impurities oxalate, and ensuring that the pH value of the mixture is in the range of 0.5-3 during the reaction; and then performing solid-liquid separation treatment on the solid-liquid mixture obtained after the reaction. The method can effectively remove heavy metal ion impurities such as manganese, cadmium, lead, nickel and chromium in the solution containing iron salts, and can also reduce the loss of iron ions to improve the yield.

Description

Technical Field

[0001] This invention specifically relates to a method and apparatus for removing heavy metal ion impurities from iron-containing salts. Background Technology

[0002] In nature, iron ore often contains trace amounts of other heavy metals, such as copper, manganese, cadmium, zinc, and lead. Furthermore, to improve the applicability of steel for different applications, the modern steel industry typically adds metals such as chromium, nickel, manganese, and titanium during the steelmaking process. Both iron ore and scrap steel from the steel industry are commonly used iron sources in the manufacture of iron-containing salt solutions. Most commercially available iron-containing salt solutions are made from iron-containing waste, while higher-purity solutions use iron ore as the iron source, resulting in a price at least 25% higher. Because these iron sources contain impurities other than iron, iron-containing salt solutions often also contain various heavy metal ions such as nickel, chromium, manganese, and cadmium ions.

[0003] Heavy metals can interact strongly with proteins and various enzymes in the human body, causing them to lose activity, or they can accumulate in certain organs, leading to poisoning. Furthermore, the vast majority of heavy metal ions cannot be broken down in water. Heavy metals existing in various chemical states or forms will remain, accumulate, and migrate after entering the environment or ecosystem, causing pollution. For example, heavy metal ions discharged with wastewater, even at low concentrations, can accumulate in algae and sediment and be adsorbed onto the surface of fish and shellfish, or combine with other toxins in the water to form more toxic organic compounds. Therefore, current regulations have strict requirements on the heavy metal content in discharged industrial wastewater.

[0004] Iron-containing salt solutions have wide applications in production and daily life, such as wastewater treatment, metal etching, concrete preparation, printing and dyeing, metallurgy, coloring, and pharmaceuticals. They can also be used as agricultural fertilizer and as raw materials for producing iron-containing products. Therefore, it is necessary to remove harmful heavy metal elements from iron-containing salt solutions during their chemical use. Furthermore, while recovering and reusing iron from iron-containing salt waste liquids, it is also essential to remove various harmful heavy metal elements.

[0005] Currently, common iron-containing salt solutions and waste liquids (hereinafter collectively referred to as iron-containing salt solutions) are usually acidic aqueous solutions containing one or more of ferric chloride, ferrous chloride, ferrous sulfate, ferrous sulfate, and ferric nitrate. Existing methods for removing heavy metal ions from iron-containing salt solutions typically involve: first, introducing iron metal into the iron-containing salt solution to reduce ferric ions to ferrous ions, and displacing and reducing nickel ions to metallic nickel; simultaneously, reducing high-valent manganese ions to ferrous ions and hexavalent chromium ions to ferric ions; then, adjusting the pH of the resulting solution, which is predominantly composed of ferrous ions, with sodium hydroxide to cause the chromium ions to precipitate as chromium hydroxide, thus removing the chromium ions.

[0006] Its drawback is that the removal of heavy metal impurities cannot be balanced with the loss of iron ions:

[0007] (1) The optimal solution pH for removing chromium ions by generating chromium hydroxide in the above method is 5 to 7. At this pH, the ferrous ions in the solution will also react to generate a certain amount of ferrous hydroxide precipitate, resulting in the loss of ferrous ions. When the pH is lower than the above range, although the loss of ferrous ions can be reduced, more chromium ions will remain in the solution.

[0008] (2) The above method cannot remove manganese and cadmium ions. This is because the optimal solution pH for removing manganese and cadmium ions by adding sodium hydroxide to generate manganese hydroxide and cadmium hydroxide is 7 to 9. This pH range largely overlaps with the pH range for precipitation of ferrous hydroxide. Therefore, it is impossible to remove manganese and cadmium ions from the iron-containing solution while retaining more iron ions.

[0009] (3) When sodium hydroxide is added to adjust the pH of the solution upward, the local concentration of the solution is uneven, resulting in an excessively high local pH value. This causes the solution to easily form ferrous hydroxide precipitate in some areas, resulting in the loss of iron ions.

[0010] Iron-containing chemicals are widely used raw materials in industrial production and water treatment, and the demand is very large. Because manganese and chromium ions in iron-containing salt solutions cannot be effectively removed, they can introduce heavy metal impurities into the process, causing side reactions or adverse effects. When used in water treatment, they can introduce heavy metal impurities, leading to excessive levels of heavy metals. Therefore, existing iron-containing salt solutions are not suitable for producing industrial products with high requirements or for use in industrial production processes with high requirements, nor are they suitable for domestic water purification.

[0011] Therefore, the industry is still looking forward to using other more effective methods to remove heavy metal ions from iron salt solutions, so as to remove heavy metal ions from iron salt solutions more thoroughly and reduce environmental pollution in widespread use. Summary of the Invention

[0012] The first objective of this invention is to provide a method for removing heavy metal ion impurities from iron-containing salt solutions. This method can effectively remove heavy metal ion impurities such as manganese, cadmium, lead, nickel, and chromium from iron-containing salt solutions, while reducing iron ion loss to improve yield.

[0013] A second objective of this invention is to provide an apparatus suitable for the method of removing heavy metal ion impurities from iron-containing salt solutions.

[0014] The first objective of this invention is achieved through the following technical solution:

[0015] A method for removing heavy metal ion impurities from an iron-containing salt solution, characterized by comprising the following steps:

[0016] Step 1: The iron-containing salt solution to be treated is oxidized by adding an oxidant and / or by electrochemical methods to obtain an iron-containing acidic solution A;

[0017] Alternatively, the iron-containing salt solution to be treated can be oxidized by adding an oxidant and / or by electrochemical methods, and then reduced by adding a reducing agent and / or by electrochemical methods to obtain an iron-containing acidic solution A;

[0018] The redox potential of the iron-containing acidic solution A is 100-700 mV;

[0019] Step 2: Add oxalic acid and / or oxalate to the iron-containing acidic solution A obtained in Step 1, mix them, and let the heavy metal ion impurities in the solution react chemically to form a precipitate of heavy metal impurity oxalate. During the reaction, ensure that the pH value of the mixture is within the range of 0.5-3.

[0020] Then, the solid-liquid mixture obtained after the reaction is subjected to solid-liquid separation treatment.

[0021] The iron-containing salt solution to be treated in this invention is specifically an iron-containing salt solution containing heavy metal ion impurities.

[0022] The inventors discovered that oxalate ions can react with low-valence heavy metal ions such as ferrous ions, manganese ions, cadmium ions, lead ions, nickel ions, ferrous ions, and chromium ions to form insoluble cadmium oxalate, lead oxalate, manganese oxalate, nickel oxalate, ferrous oxalate, and chromium oxalate. However, in acidic environments, oxalate ions are difficult to react with high-valence manganese ions, hexavalent chromium ions, and ferric ions to form precipitates. Therefore, this invention utilizes the property that oxalic acid and / or oxalates can react with some of the above-mentioned heavy metal ions to form insoluble substances to remove heavy metal ion impurities. Moreover, before adding oxalic acid and / or oxalates, the ferrous ions in the iron-containing solution to be treated are first oxidized to ferric ions, thereby reducing the loss of iron source during the subsequent removal of heavy metal ion impurities. When the redox potential of the iron-containing acidic solution A is 100-700mV, the iron-containing acidic solution A contains an appropriate amount of ferric ions, while most of the heavy metal ions such as manganese ions, cadmium ions, lead ions, nickel ions, and chromium ions are in a low valence state, thus enabling the precipitation reaction and removal of heavy metal ion impurities.

[0023] This invention oxidizes the iron-containing salt solution to be treated by adding an oxidizing agent and / or using an electrochemical oxidation reaction, enabling the ferrous ions in the iron-containing solution to be oxidized to ferric ions. However, when the redox potential of the iron-containing solution to be treated is higher than 700 mV, a large number of heavy metal ion impurities in the solution will also be oxidized to a higher valence state. In this case, by adding a reducing agent and / or using an electrochemical reduction reaction, the redox potential of the oxidized iron-containing solution to be treated with a redox potential higher than 700 mV is adjusted downward to the range of 100-700 mV. This allows most of the iron ions in the solution to remain in the ferric ion state while reducing the valence of the high-valence heavy metal ion impurities that have a higher oxidizing power than ferric ions to lower valence states. Thus, most of the iron ions in the iron-containing acidic solution A obtained in step one exist in the ferric ion state, while all or most of the heavy metal ion impurities exist in the lower valence state. Furthermore, when the iron-containing solution to be treated contains nitrate ions, the original nitrate ions in the solution can be decomposed and consumed through the chemical reaction of variable valence metal ions during the process of adjusting the redox potential of the solution downward.

[0024] In step two, by adding oxalic acid and / or oxalate to the iron-containing acidic solution A, when the pH of the resulting mixture is in the range of 0.5-3, the low-valence heavy metal ion impurities in the iron-containing acidic solution A can combine with oxalate ions to form water-insoluble heavy metal impurity oxalate precipitates.

[0025] Since the heavy metal impurity oxalate readily reacts with acid and dissolves back, the pH of the solution in which the precipitation reaction occurs is closely related to the precipitation removal rate of heavy metal ion impurities. To improve the removal rate of heavy metal ion impurities, the pH of the solution environment needs to be adjusted to create suitable pH reaction conditions to promote the reaction and generate heavy metal impurity oxalate, while preventing its back dissolution. In step two, the addition of oxalic acid and / or oxalate to the iron-containing acidic solution A can be performed simultaneously with the pH adjustment operation involving the addition of acidic or alkaline substances, or in any order, to allow the solution to react and precipitate insoluble heavy metal impurity oxalate and ferrous oxalate precipitates. The reaction mixture can also be stirred and the temperature controlled during the reaction process to further promote the formation of heavy metal impurity oxalate.

[0026] After the solid-liquid separation process in step two removes the oxalate precipitate containing heavy metal impurities, the resulting filtrate is an iron salt solution in which most of the heavy metal ion impurities have been removed.

[0027] The oxidant is selected from one or more of hydrogen peroxide, sodium perchlorate, potassium perchlorate, sodium chlorate, potassium chlorate, sodium hypochlorite, calcium hypochlorite, sodium chlorite, sodium dichromate, potassium dichromate, sodium percarbonate, potassium percarbonate, potassium permanganate, sodium perborate, potassium perborate, sodium persulfate, potassium persulfate, ammonium persulfate, chlorine, ozone, oxygen, and air; the above oxidants can be combined in any proportion. Preferably, the oxidant is selected from one or more of sodium persulfate, sodium chlorate, chlorine, ozone, oxygen, air, and hydrogen peroxide.

[0028] In step one, the iron-containing salt solution to be treated is oxidized by an electrochemical method. Specifically, the iron-containing salt solution to be treated is placed in the anode area of ​​the electrolytic cell, and the electrochemical reaction at the anode is used to oxidize it.

[0029] In step one, the iron-containing salt solution to be treated is reduced by an electrochemical method. Specifically, the iron-containing salt solution to be treated is placed in the cathode area of ​​the electrolytic cell, and the reduction is carried out by the electrochemical reaction at the cathode.

[0030] The reducing agent is selected from one or more of ferrous metals, ferrous sulfate, ferrous chloride, ferrous hydroxide, sodium sulfite, and sodium bisulfite; the reducing agents can be combined in any proportion. The reducing agent can be added directly or dissolved in water to form an aqueous solution for addition.

[0031] The oxalic acid and / or oxalate salts mentioned in step two can be added directly or dissolved in water to form an aqueous solution. The amount of oxalic acid and / or oxalate salts added is determined based on the amount of heavy metal ion impurities to be removed from the iron salt solution.

[0032] In a preferred embodiment of the present invention, the redox potential of the iron-containing acidic solution A is 300-700mV.

[0033] Since adding an oxidant to the iron-containing salt solution in step one is costly and may introduce new impurities into the solution, it is preferable that electrolytic cell B is used in step one to oxidize the iron-containing salt solution through an electrochemical method. Specifically, electrolytic cell B includes an insoluble anode, an insoluble cathode, an electrolytic cell separator, and an electrolytic power source, and is divided into an anode tank area and a cathode tank area by the electrolytic cell separator.

[0034] More preferably, the insoluble anode of electrolytic cell B is selected from one or more of conductive graphite, titanium-based coated electrodes, gold, platinum, and alloys containing the above metals; the insoluble cathode of electrolytic cell B is selected from one or more of conductive graphite, stainless steel, gold, platinum, silver, copper, iron, nickel, tin, zinc, aluminum, titanium, and alloys containing the above metals. The electrolytic cell separator of electrolytic cell B is a material that can effectively prevent metal cations from migrating from the anode area to the cathode area of ​​electrolytic cell B during operation, specifically selected from one or more of anion exchange membranes, bipolar membranes, reverse osmosis membranes, and neutral filter membranes; the anolyte of electrolytic cell B is an iron-containing salt solution to be treated, and the catholyte of electrolytic cell B is an aqueous electrolyte solution.

[0035] More preferably, the insoluble anode of the electrolytic cell B is a titanium-based coated electrode, the separator of the electrolytic cell is an anion exchange membrane, and the anion in the cathode electrolyte is one or more of the anion types contained in the anolyte.

[0036] When the insoluble anode and insoluble cathode of the electrolytic cell B are connected to the positive and negative terminals of the electrolytic power supply, respectively, and are immersed in the anolyte and cathode electrolyte, respectively, an oxidation reaction is carried out on the anolyte by applying electricity: in the electrochemical oxidation process, in addition to oxidizing the ferrous ions in the iron-containing salt solution to be treated to ferric ions, the ferric ions in the solution are also oxidized to hexavalent chromium ions and / or the low-valent manganese ions are oxidized to high-valent manganese ions.

[0037] In a preferred embodiment, the oxidation result of metal ions can be obtained by laboratory testing or ORP electrode measurement during the electrochemical oxidation of the iron-containing salt solution to be treated. During the electrochemical oxidation process, process testing and / or process control using a redox potentiometer are required to detect whether the concentration of ferric ions generated meets the process concentration requirements. Once the concentration of ferric ions in the oxidized iron-containing salt solution reaches the process concentration requirement, the electrolytic power supply is shut down to stop the electrochemical oxidation operation.

[0038] The present invention can be improved as follows: A sulfide is added to the iron-containing acidic solution A obtained in step one, causing heavy metal ion impurities such as mercury, lead, and zinc to combine with sulfur ions to form mercuric sulfide, lead sulfide, and zinc sulfide precipitates. The precipitates are removed by solid-liquid separation before proceeding to step two, or they can be removed by solid-liquid separation in step two. Preferably, the sulfide is at least one selected from sodium sulfide, potassium sulfide, and hydrogen sulfide; the sodium sulfide, potassium sulfide, and hydrogen sulfide can be combined in any proportion.

[0039] This invention can be improved as follows: To obtain a solution of iron-containing salts with a high iron ion concentration, or to increase the iron ion concentration in the solution of iron-containing salts while removing heavy metal ion impurities, thereby further improving product value, this invention adds iron metal to an acidic liquid or the solution of iron-containing salts to be treated, and / or uses the acidic liquid or the solution of iron-containing salts to be treated as an electrolyte and the iron metal as a soluble anode to carry out an electrolytic reaction, thereby increasing the iron ion concentration in the solution and creating a new solution of iron-containing salts to be treated. Step one can be performed simultaneously with this improved step, or in an alternating manner, or step one can be performed after completing this improved step.

[0040] Preferably, the acidic liquid is an acidic solution with one or more of the following as its main components: hydrochloric acid, sulfuric acid, ferric chloride, ferrous chloride, ferric sulfate, and ferrous sulfate.

[0041] Preferably, before proceeding to step two, the iron-containing acidic solution A undergoes solid-liquid separation. Since iron metal often contains sulfur impurities, sulfur will chemically react with some heavy metal ion impurities in the solution during the iron's dissolution process, forming sulfide precipitates of heavy metal impurities. These precipitates need to be removed through solid-liquid separation.

[0042] When using an acidic liquid or a solution of iron-containing salts as the electrolyte and an iron-containing metal as the soluble anode to increase the concentration of iron ions in the solution: Electrolytic cell A is used, in which an iron-containing metal or iron fragments contained in a titanium basket are used as the soluble electrolytic anode. When electrolytic cell A is connected to the electrolytic power supply for electrolysis, two main chemical reactions occur in the solution within electrolytic cell A.

[0043] (1) Reaction of iron metal with acid in electrolyte: ;

[0044] (2) Electrochemical reaction at the soluble electrolytic anode: ;

[0045] Electrochemical reactions at the insoluble electrolytic cathode: .

[0046] When the electrolyte contains nitric acid, the excess metallic iron and the ferrous ions in the electrolyte will further decompose and deplete the nitrate ions in the iron-containing salt solution. The specific chemical reaction equation is as follows:

[0047] 3Fe+8HNO3→3Fe(NO3)2+2NO↑+4H2O;

[0048] 3Fe 2+ +NO3 - +4H + →3Fe 3+ +NO↑+2H2O.

[0049] Preferably, in order to ensure the smooth and continuous progress of the electrolysis reaction, an acidic substance is added to electrolytic cell A during the electrolysis process.

[0050] Preferably, a hydrometer and / or pH meter are used to monitor and control the process data of the solution in electrolytic cell A. A higher specific gravity value indicates a higher iron content in the resulting iron-containing salt solution. Using a pH meter to control the reaction means that, given a certain acidity in the original solution, a higher pH value after iron dissolution indicates a greater amount of dissolved iron in the solution.

[0051] More preferably, once the iron ion concentration in the obtained iron-containing salt solution has reached the process requirements, the electrolysis power supply is turned off, and / or the soluble anode is removed.

[0052] Preferably, the electrolytic cathode of the electrolytic cell A is an insoluble cathode, specifically selected from at least one of conductive graphite, gold, platinum, silver, copper, nickel, iron, titanium, stainless steel, and alloys containing any of the above metals. When the electrolytic cathode of the electrolytic cell A is made of the above materials, some of the nickel ions in the electrolyte can be electrolyzed onto the cathode during the electrolysis of molten iron, thereby reducing the nickel ion concentration in the iron-containing salt solution. More preferably, the electrolytic cathode of the electrolytic cell A is titanium and / or a titanium alloy.

[0053] This invention can be further improved: when using an acidic liquid or an iron-containing salt solution as the electrolyte to increase the iron ion concentration in the solution via electrolysis, a soluble anode and an insoluble anode are simultaneously set in the electrolytic cell A. The soluble anode is an iron-containing metal, and the acidic liquid or iron-containing salt solution does not contain nitric acid. The presence of the soluble anode results in the presence of iron metal in the electrolytic cell A, causing the generation of ferrous ions in the electrolyte. To accelerate the iron dissolution rate, an insoluble anode is added to the electrolytic cell A, causing the ferrous ions in the electrolyte to be oxidized to ferric ions due to the electrochemical reaction of the insoluble anode. This oxidizing ferrous ions helps corrode the iron metal, thereby increasing the iron dissolution rate of the electrolyte and simultaneously shifting the pH value of the electrolyte upwards. The specific reaction is as follows:

[0054] Electrochemical reactions at the insoluble electrolytic anode: .

[0055] The chemical reaction of ferric ions corroding ferrous metals: .

[0056] Preferably, in step one, when the iron-containing salt solution to be treated is oxidized and then reduced by adding a reducing agent and / or by using an electrochemical method, the concentration of heavy metal ion impurities in the iron-containing salt solution to be treated or the oxidized iron-containing salt solution to be treated is detected and measured. Based on the detection results, an appropriate amount of reducing agent is added to the oxidized iron-containing salt solution to be treated to completely reduce the high-valence heavy metal ions to the lowest valence state, thereby obtaining an iron-containing acidic solution A.

[0057] Preferably, the reducing agent in step one is at least one selected from iron powder, ferrous hydroxide, ferrous chloride, and ferrous sulfate.

[0058] Preferably, in step one, after oxidizing the iron-containing salt solution to be treated, an electrochemical reduction reaction is performed. The oxidized iron-containing salt solution to be treated is added to the cathode area of ​​the electrolytic cell B for reduction, so that the high-valence heavy metal ion impurities in the solution are reduced to low-valence heavy metal ions, resulting in an iron-containing acidic solution A. At this time, the electrolytic cathode material of the electrolytic cell B is one or more selected from conductive graphite, gold, platinum, silver, titanium, iron, alloys containing the above metals, and stainless steel.

[0059] Preferably, the oxalate in step two is sodium oxalate and / or potassium oxalate.

[0060] Preferably, the alkaline substance used to adjust the pH value in step two is selected from at least one of sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, potassium carbonate, and potassium bicarbonate, and the above alkaline substances can be combined in any proportion.

[0061] Preferably, in step two, an alkaline substance is first used to adjust the pH value of the iron-containing solution A to the pH value close to the precipitation of ferric hydroxide or to the point where the solution begins to become turbid and ferric hydroxide precipitates slightly. Then, appropriate amounts of oxalic acid and / or oxalate are added to it in batches and multiple times to give the heavy metal ions more opportunities to undergo chemical reactions to produce water-insoluble oxalate precipitates.

[0062] The second objective of this invention is achieved through the following technical solution:

[0063] An apparatus suitable for the method of removing heavy metal ion impurities from iron-containing salt solutions, characterized in that it comprises a chemical reaction tank, a redox potentiometer, a stirring device, a solid-liquid separator, and a temporary storage tank; wherein:

[0064] The chemical reaction tank is used for at least one of the following treatment steps: oxidation treatment of the iron-containing salt solution to be treated, reduction treatment of the oxidized iron-containing solution to be treated, and chemical reaction precipitation treatment of iron-containing acidic solution A with oxalic acid and / or oxalate.

[0065] The redox potentiometer is used for detection and control according to process requirements during the oxidation and / or reduction treatment of the iron-containing salt solution to be treated; the solid-liquid separator is used for solid-liquid separation of the precipitate that appears in the solution after the chemical reaction in the tank; the temporary storage tank is used for temporary storage of the clear liquid obtained after filtration by the solid-liquid separator.

[0066] The present invention can be improved as follows: an electrolytic cell B is added and connected to a chemical reaction tank for oxidizing and / or reducing the iron-containing salt solution to be treated. In electrolytic cell B, a redox potentiometer is used to monitor and control the oxidation and / or reduction reactions.

[0067] Electrolytic cell B is divided into an anode cell and an cathode cell by a separator. Specifically, the anode cell of electrolytic cell B is used to oxidize ferrous ions in the iron-containing salt solution to ferric ions. The cathode cell of electrolytic cell B can perform ordinary water electrolysis or electroreduction of high-valence ions, and can also be used to reduce the high-valence heavy metal ions in the oxidized iron-containing salt solution to low-valence heavy metal ions.

[0068] The main function of the separator in electrolytic cell B is to prevent cations in the electrolyte from migrating between the anode and cathode regions during electrolysis. The separator is at least one of anion exchange membranes, bipolar membranes, reverse osmosis membranes, and neutral filtration membranes, with anion exchange membranes being preferred.

[0069] The electrolytic anode of electrolytic cell B can be made of one or more of the following materials: conductive graphite, titanium-based coated electrode, gold, platinum, and gold / platinum alloy. The electrolytic anode is preferably made of titanium-based coated electrode. The electrolytic cathode of electrolytic cell B can be made of one or more of the following materials: conductive graphite, gold, platinum, silver, titanium, gold / platinum / silver / titanium alloy, stainless steel, and iron.

[0070] The present invention can be improved as follows: a precipitation reaction tank is added, which is connected to the chemical reaction tank and / or electrolytic cell B for use in chemical neutralization treatment and / or precipitation reaction processes; the bottom of the precipitation reaction tank has a funnel-shaped structure. The funnel-shaped structure at the bottom of the precipitation reaction tank allows for better collection of precipitates from the chemical reaction, thus improving efficiency; furthermore, this frees up the chemical reaction tank and / or electrolytic cell B from being used as a precipitation reaction tank, thereby saving on equipment investment.

[0071] The present invention can be improved in the following ways: In order to improve the product value by producing a solution with a higher iron concentration, two methods can be used: adding iron metal fragments to the acid solution to dissolve the iron in the acid solution or using electrolysis to dissolve the iron in the acid solution. This method can be carried out simultaneously with step one or before step one.

[0072] In a preferred embodiment of the present invention, the method of dissolving iron in acid by electrolysis involves: adding an electrolytic cell A, wherein the electrolytic anode is a soluble anode of iron; and the electrolytic cathode is at least one selected from conductive graphite, stainless steel, gold, platinum, silver, copper, iron, titanium, and alloys of the above metals, serving as an insoluble cathode. The mixture treated in electrolytic cell A is then sent to a chemical reaction tank and / or a precipitation reaction tank and / or electrolytic cell B for further processing. When the iron-containing solution contains nickel ions, because the cathode of electrolytic cell A is an insoluble cathode, some nickel ions can be electrolyzed onto the cathode during the iron dissolution process, thereby reducing the nickel ion concentration in the iron-containing solution.

[0073] Preferably, a hydrometer and / or pH meter are installed in electrolytic cell A for detection and process control. The higher the specific gravity value, the higher the iron content of the resulting iron-containing solution. By using a pH meter to control the reaction, given a constant acidity in the original solution, the higher the pH value after iron dissolution, the greater the amount of iron dissolved.

[0074] This invention can be further improved as follows: In electrolytic cell A, an iron-containing salt solution is prepared in an acidic electrolyte using iron metal as a soluble anode. Because electrolytic cell A contains excess iron metal, the iron-containing salt solution obtained in this iron-dissolving process is an aqueous solution primarily composed of ferrous ions (Fe2+). To accelerate the iron-dissolving rate, the anode performance structure of electrolytic cell A is modified so that, during the iron-dissolving process, ferrous ions are oxidized to ferric ions (Fe3+) under the electrochemical reaction of the anode. Specifically, in electrolytic cell A, an insoluble electrolytic anode device is added to the existing soluble anode, resulting in the presence of both insoluble and soluble iron anodes in electrolytic cell A. Adding the insoluble electrolytic anode device introduces ferric ions into the electrolyte. These ferric ions help corrode the iron metal, thereby increasing the iron-dissolving rate and raising the pH value of the iron-containing solution to near the critical point for the precipitation of ferric hydroxide. Once the iron ion concentration in the prepared iron-containing salt solution has reached the process requirements, stop adding iron fragments to the titanium basket in electrolytic cell A, and remove the iron fragments from the titanium basket or remove the entire titanium basket from the electrolyte, or turn off the electrolytic power supply.

[0075] The present invention can be improved as follows: exhaust hoods or exhaust pipes are installed on the top of the chemical reaction tank, electrolytic tank B, precipitation reaction tank and electrolytic tank A to collect and treat the gases released by the liquid in the tank area during the chemical reaction.

[0076] The present invention can be improved in the following way: multiple temporary storage tanks are added to store iron salt solutions and various solutions in the process.

[0077] The present invention can be improved in the following way: by adding a vacuum jet device and a liquid spraying device, so as to use the jet and / or spraying device to mix gas and liquid to treat the reaction gas generated in the chemical reaction tank, electrolytic tank B, precipitation reaction tank, electrolytic tank A and temporary storage tank.

[0078] The present invention can be improved as follows: In order to remove oil from the iron-containing salt solution before the operation in step one, a water-oil separator is added to separate the oil in the iron-containing solution, and a solid-liquid separator is set after the water-oil separator to adsorb organic impurities in the solution using its filter medium.

[0079] The present invention can be improved by adding detection sensors and placing them in the various tanks and / or pipes through which the liquid flows, so as to automatically detect process data during the process of removing heavy metals from the iron-containing salt solution.

[0080] The detection sensor devices include one or more of the following: level gauge, pH meter, hydrometer, acidity meter, redox potentiometer, and COD detector.

[0081] The present invention can be improved in the following way: an automatic detection and feeding controller is added to automatically control the iron salt solution during the heavy metal removal process according to the on-site data obtained from the detection, thereby ensuring safe production.

[0082] The present invention can be improved in the following way: a solution stirrer is added to the above-mentioned tanks to make the chemical reaction of the solution reactants in the tank uniform and safe and controllable.

[0083] The present invention can be improved in the following way: a solution hot and cold temperature exchanger is added to the chemical reaction tank and / or electrolytic tank B and / or precipitation reaction tank and / or electrolytic tank A, so that the chemical reaction of the solution is carried out at a process-controllable temperature, which can improve the reaction rate efficiency and achieve safe production.

[0084] Compared with the prior art, the present invention has the following beneficial effects.

[0085] 1. This invention can remove heavy metal ion impurities such as manganese, cadmium, lead, nickel, and chromium from iron-containing salt solutions, while reducing the loss of iron ions, so as to ensure that the product meets the required specifications.

[0086] Moreover, compared to iron ore-based solutions with higher purity, the method of this invention can convert iron ore-based solutions with lower heavy metal impurities into products with lower purity. This increases the source of raw materials for high-purity products, promotes the application of iron-containing products, and better realizes the utilization of iron-containing waste.

[0087] 2. This invention can complete a round of treatment for removing heavy metal ion impurities from iron-containing salt solutions within a few hours. The process has a short operating time, minimal iron loss, and high production efficiency, making it suitable for large-scale production applications.

[0088] 3. The method of this invention removes heavy metal ion impurities from iron-containing salt solutions, enabling iron-containing salt solutions to be more widely used in water purification and further promoted for use in the production of industrial products or industrial production processes with high requirements.

[0089] 4. The process for treating iron-containing salt solutions according to this invention can be automated, reducing the labor intensity of workers.

[0090] 5. The present invention provides a simple, low-investment, and quick-resulting process for removing heavy metal ion impurities from iron-containing salt solutions.

[0091] 6. This invention can effectively remove heavy metal ion impurities using widely used iron-containing salts, which has significant implications for environmental protection. Attached Figure Description

[0092] Figure 1 This is the device used in Example 1 for removing heavy metal ion impurities from iron-containing salt solutions;

[0093] Figure 2 This is the device used in Example 2 for removing heavy metal ion impurities from iron-containing salt solutions;

[0094] Figure 3 This is the device used in Example 3 for removing heavy metal ion impurities from iron-containing salt solutions;

[0095] Figure 4 This is the device used in Example 4 for removing heavy metal ion impurities from iron-containing salt solutions;

[0096] Figure 5 This is the device used in Example 5 for removing heavy metal ion impurities from iron-containing salt solutions.

[0097] Figure reference numerals: 11-Electrolytic cell A, 12-Electrolytic cell A with titanium basket anode, 13-Insoluble anode of electrolytic cell A, 14-Cathode of electrolytic cell A, 15-Electrolytic cell B, 16-Anode of electrolytic cell B, 17-Cathode of electrolytic cell B, 18-Electrolytic cell separator, 19~20-Chemical reaction tank, 21~24-Oxidation-reduction potentiometer, 25~30-Solid-liquid separator, 31~35-Temporary storage tank, 36~38-Impeller agitator, 39-~42-Circulating liquid flow agitator, 43~45-Solid feeding mechanism, 46~48-Water-oil separator 49~53-Vacuum jet generator, 54~56-Liquid spraying device, 57~60-Tank cover exhaust hood or exhaust pipe, 61~62-Heat and cold exchanger, 63~69-Detection device, 71-Automatic detection and feeding controller, 72~73-Hydrogen direct exhaust device, 74~75-Precipitation reaction tank, 76~80-Feeding port, 81~84-Tail gas discharge port, 85-Iron salt solution containing heavy metal ion impurities, 86~87-Electrolysis power supply, 88-COD detector, 89~99-Valve, 100~110-Pump. Detailed Implementation

[0098] The present invention will be further described below through specific embodiments.

[0099] In the embodiments described below, the electrolytic cell A, electrolytic cell B, electrolytic cathode and anode electrodes, chemical reaction tank, solid-liquid separator, precipitation reaction tank, automatic detection and feeding controller, temporary storage tank, liquid jetter, and liquid spraying device used are all manufactured by Foshan Yegao Environmental Protection Equipment Co., Ltd.; the electrolytic cell separators, detection devices, and oxidation-reduction potentiometers used, including ferric chloride, potassium dichromate, nickel chloride, hydrogen peroxide, and ferrous sulfate, are all commercially available products. Besides those listed above, those skilled in the art can also choose other products with similar performance to those listed above, based on conventional selection, to achieve the objectives of this invention.

[0100] Example 1

[0101] like Figure 1 The diagram shows a basic embodiment of the method for removing heavy metal ion impurities from iron-containing salt solutions according to the present invention. The equipment used includes a chemical reaction tank 19, a redox potentiometer 21, a solid-liquid separator 25, a temporary storage tank 31, and an impeller-type stirrer 36. The chemical reaction tank 19 is connected to the solid-liquid separator 25 via a valve 89 and a pump 100. The outlet of the solid-liquid separator 25 is connected to the temporary storage tank 31, which is equipped with a tail gas discharge port 81. The chemical reaction tank 19 is equipped with an impeller-type stirrer 36 and a redox potentiometer 21.

[0102] In this embodiment, the iron salt solution 85 containing heavy metal ion impurities to be treated is an aqueous solution with ferrous chloride and ferrous sulfate as the main components, and the heavy metal impurities are mainly chromium and nickel.

[0103] This embodiment 1 is performed according to the following steps:

[0104] (1) Inject the iron salt solution 85 containing heavy metal ion impurities into the chemical reaction tank 19, and install the redox potentiometer 21 in the tank and immerse it in the solution in the tank, and start the impeller stirrer 36.

[0105] (2) By adding a mixed solution of sodium perchlorate, potassium perchlorate, potassium chlorate, sodium chlorite, sodium hypochlorite, calcium hypochlorite, sodium dichromate, potassium dichromate, sodium persulfate and potassium persulfate (mixing ratio of each component 1:1:1:1:1:1:1:1:1:1) to the chemical reaction tank 19, the iron salt solution 85 containing heavy metal ion impurities is oxidized to the redox potential shown in Table 1, the ferrous ions in the solution are oxidized to ferric ions, while most of the heavy metal impurity ions are kept in a low valence state, thus producing an iron-containing acidic solution A with ferric ions as the main component and containing heavy metal ion impurities in the lowest valence state.

[0106] (3) Adjust the pH value of the iron-containing acidic solution A in the chemical reaction tank 19, that is, add the alkaline substance required for the neutralization reaction to the iron-containing acidic solution A, wherein the alkaline substance is a mixture of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate and potassium bicarbonate (the mixing ratio of each component is 5:1:1:1:1:1), and adjust the pH value to 1.1; then add oxalic acid solution according to the reaction amount required for the heavy metal ions to be removed in the solution, so that the solution produces water-insoluble heavy metal oxalate and ferrous oxalate precipitates; during this reaction process, add an appropriate amount of alkaline substance to maintain the original pH value of the solution.

[0107] (4) The solution in the chemical reaction tank 19 is separated into solid and liquid by the solid-liquid separator 25. The clear liquid obtained is the iron salt solution after most of the heavy metal ions have been removed, and it is temporarily stored in the temporary storage tank 31.

[0108] The removal results of this embodiment are listed in Table 1.

[0109] Example 2

[0110] like Figure 2The illustration shows an embodiment of the present invention for removing heavy metal ion impurities from iron-containing salt solutions. The equipment used includes a chemical reaction tank 19, a redox potentiometer 21, a solid-liquid separator 25, a solid-liquid separator 26, a temporary storage tank 31, a water-oil separator 46, and a detection device 63. The water-oil separator 46 is connected to the chemical reaction tank 19 via a combination of a pump 100 and the solid-liquid separator 25. The chemical reaction tank 19 is connected to the solid-liquid separator 26 via a valve 89 and a pump 101. The outlet of the solid-liquid separator 26 is connected to the temporary storage tank 31, which has a tail gas discharge port 81. The chemical reaction tank 19 is equipped with the redox potentiometer 21 and the detection device 63, which is a pH meter.

[0111] In this embodiment, the iron salt solution 85 containing heavy metal ion impurities to be treated is an aqueous solution with ferrous chloride as the main component, wherein the heavy metal impurities are mainly chromium and nickel.

[0112] This embodiment 2 is performed according to the following steps:

[0113] (1) The iron salt solution 85 containing heavy metal ion impurities is injected into the water-oil separator 46 to separate the oil layer. The overflow solution is pumped to the solid-liquid separator 25 for filtration. The filtered solution is then directed into the chemical reaction tank 19, so that the redox potentiometer 21 in the tank is immersed in the solution.

[0114] (2) Chlorine and ozone (mixed in a 5:1 ratio) are added to the chemical reaction tank 19 by means of a redox potentiometer 21 to oxidize the iron salt solution 85 containing heavy metal ion impurities to a redox potential of 650 mV. At the same time, the acidity value is measured by the detection device 63 to control the addition of hydrochloric acid, so that the ferrous ions in the solution are oxidized to ferric ions. The redox potentiometer 21 is used for process control during this reaction.

[0115] (3) After the oxidation reaction is completed, a mixed acidic solution of ferrous chloride, sodium sulfite and sodium bisulfite (mixing ratio of each component 2:1:1) is added to the solution in the chemical reaction tank 19 according to the total ion equivalent concentration of heavy metals to carry out the reduction reaction to the redox potential shown in Table 1, so that the high valence state heavy metal ions in the solution are reduced to the lowest valence state heavy metal ions, and an iron-containing acidic solution A is prepared with trivalent iron ions as the main component and containing the lowest valence state heavy metal ion impurities.

[0116] (4) Adjust the pH value of the iron-containing acidic solution A in the chemical reaction tank 19 by adding alkaline substances required for the neutralization reaction to the iron-containing acidic solution A. The alkaline substances are a mixed aqueous solution of sodium hydroxide, potassium hydroxide, sodium carbonate, and potassium carbonate and a mixture of sodium bicarbonate and potassium bicarbonate (the ratio of each component is 1:1:1:1:2:2) to raise the pH value to 0.5. Then, add a mixed solid of oxalic acid and sodium oxalate (the ratio of each component is 2:1) according to the reaction amount required to remove the heavy metal ions in the solution, so that the solution in the tank produces water-insoluble heavy metal oxalate and ferrous oxalate precipitates. During this reaction process, add an appropriate amount of alkaline substances to maintain the original pH value of the solution.

[0117] (5) The solution in the chemical reaction tank 19 is separated into solid and liquid by the solid-liquid separator 25. The clear liquid obtained is the iron salt solution after most of the heavy metal ions have been removed, and it is temporarily stored in the temporary storage tank 31.

[0118] The removal results of this embodiment are listed in Table 1.

[0119] Example 3

[0120] like Figure 3 The image shows an embodiment of the method for removing heavy metal ion impurities from iron-containing salt solutions according to the present invention. The equipment used includes a chemical reaction tank 19, a chemical reaction tank 20, an oxidation-reduction potentiometer 21, an oxidation-reduction potentiometer 22, a solid-liquid separator 25, a solid-liquid separator 26, a temporary storage tank 31, a temporary storage tank 32, an impeller-type agitator 36, an impeller-type agitator 37, a water-oil separator 46, a vacuum jet generator 49, a tank cover exhaust hood or exhaust pipe 58, a tank cover exhaust hood or exhaust pipe 59, and a heat exchanger 61. Wherein:

[0121] Chemical reaction tank 19 is equipped with an oxidation-reduction potentiometer 21, an impeller agitator 36, and a detection device 63. It also has a tank cover, an exhaust hood or an exhaust pipe 58, a feeding port 76, and a feeding port 77. The detection device 63 is a level gauge. Chemical reaction tank 20 is equipped with an oxidation-reduction potentiometer 22, an impeller agitator 37, a heat exchanger 61, and a detection device 64. It also has a tank cover, an exhaust hood or an exhaust pipe 59, a feeding port 78, and a feeding port 79. The detection device 64 is a pH meter. Temporary storage tanks 31 and 32 are respectively equipped with exhaust ports 81 and 82 at their tops.

[0122] The water-oil separator 46 is connected to the feed port 76 of the chemical reaction tank 19. The chemical reaction tank 19 is connected to the solid-liquid separator 25 via valve 89 and pump 101. The solid-liquid separator 25 is connected to the feed port 78 of the chemical reaction tank 20. The chemical reaction tank 20 is also connected to the solid-liquid separator 26 and the temporary storage tank 31 in sequence via valve 90 and pump 101. The vacuum jet injector 49 and the temporary storage tank 32 form a waste gas treatment assembly. The tank cover exhaust hood or exhaust pipe 58, the tank cover exhaust hood or exhaust pipe 59, and the tail gas discharge port 81 are all connected to this waste gas treatment assembly.

[0123] In this embodiment, the iron salt solution 85 containing heavy metal ion impurities to be processed is a solution with ferrous sulfate as the main component, wherein the heavy metal impurities are mainly mercury, manganese, nickel, chromium, cadmium and zinc.

[0124] The method in this embodiment 3 is performed according to the following steps.

[0125] (1) The iron salt solution 85 containing heavy metal ion impurities is injected into the water-oil separator 46. After the oil layer is separated, the solution flows into the chemical reaction tank 19. The stirrer 36 and the detection device 63 installed in the tank start working. Sodium sulfide, potassium sulfide and hydrogen sulfide mixture (each component added in a ratio of 1:1:1) are added to the chemical reaction tank 19 through the feed port 77 according to the amount of sulfur element required to remove mercury, zinc and cadmium heavy metal ions in the solution. The solution in the tank undergoes a chemical reaction and some heavy metal sulfide precipitates are produced. Then, the solid-liquid separator 25 is used to remove mercury sulfide, zinc sulfide, cadmium sulfide and so on. After filtration through the solid-liquid separator 25, the solution is pumped to the chemical reaction tank 20 through the feed port 78.

[0126] (2) Oxidizing agent and sulfuric acid are added to the chemical reaction tank 20 through the feed port 79. The oxidizing agent is a mixed solution of hydrogen peroxide, sodium percarbonate, potassium percarbonate, sodium perborate, ammonium persulfate and potassium perborate, as well as oxygen and air (the ratio of each component added is 10:1:1:1:1:1:1:1). This causes the ferrous ions in the iron salt solution 85 containing heavy metal ion impurities in the tank to be oxidized to ferric ions. At the same time, the low-valence ions of heavy metals in the solution are also oxidized to high-valence heavy metal ions. During this reaction process, stirring and constant temperature control are continuously performed. The oxidation process is also controlled by the oxidation-reduction potentiometer 22 until the solution reaches the oxidation-reduction potential value required by the process.

[0127] (3) After the oxidation reaction is completed, a reducing agent is added to the solution in the chemical reaction tank 20 according to the reaction equivalent of the total heavy metal ion concentration. The reducing agent is a solution of metallic iron, ferrous hydroxide and ferrous sulfate (each component is added in a ratio of 1:1:3). While stirring and mixing, a reducing chemical reaction is carried out to the redox potential shown in Table 1, so that the high-valence heavy metal ions in the solution are reduced to the lowest valence heavy metal ion impurities, and an iron-containing acidic solution A is prepared, which is mainly composed of ferric ions and contains the lowest valence heavy metal ion impurities.

[0128] (4) Adjust the pH value of the iron-containing acidic solution A in the chemical reaction tank 20. Add the alkaline substance required for the neutralization reaction to the iron-containing acidic solution A through the feed port 79. The alkaline substance is a mixed solution of sodium hydroxide, potassium hydroxide and sodium carbonate (the ratio of each component is 2:1:1) to adjust the pH value to 2.3. Then add a mixed solution of sodium oxalate and potassium oxalate (the ratio of each component is 1:1). During this reaction, add an appropriate amount of sulfuric acid to maintain the original pH value of the solution. Without causing too much iron hydroxide to precipitate, the solution in the tank produces heavy metal oxalate precipitate that is insoluble in weak acid aqueous solution.

[0129] (5) The solution in the chemical reaction tank 20 is separated into solid and liquid by the solid-liquid separator 26. The clear liquid obtained is the iron salt solution with most heavy metal ion impurities removed, and is temporarily stored in the temporary storage tank 31.

[0130] In the above steps, the exhaust gases from chemical reaction tank 19 and chemical reaction tank 20 and the exhaust gases from temporary storage tank 31 are directed to the waste gas treatment combination system of temporary storage tank 32 and vacuum jet 49 for treatment; wherein the exhaust gas absorption liquid stored in temporary storage tank 32 is sodium hydroxide solution.

[0131] The removal process results of this embodiment are listed in Table 1.

[0132] Example 4

[0133] like Figure 4The image shows an embodiment of the present invention for removing heavy metal ion impurities from iron-containing salt solutions. The equipment used includes an electrolytic cell A11, an electrolytic cell A with a titanium basket anode 12, an electrolytic cell A cathode 14, a redox potentiometer 21, a redox potentiometer 22, a solid-liquid separator 25, a solid-liquid separator 26, a temporary storage tank 31, a temporary storage tank 32, a circulating liquid flow agitator 39, a circulating liquid flow agitator 40, a solid feeding mechanism 43, and a water-oil separator. 46. ​​Liquid spraying device; 54. Tank cover exhaust hood or exhaust pipe; 59. Tank cover exhaust hood or exhaust pipe; 60. Detection device; 63. Detection device; 64. Hydrogen direct vent; 72. Precipitation reaction tank; 74. Feed port; 76. Feed port; 77. Feed port; 78. Electrolysis power supply; 86. COD detector; 88. Valve; 89. Valve; 90. Valve; 91. Pump; 100. Pump; 101. Pump; 102. Pump; 103. Pump; 104. Among them:

[0134] The water-oil separator 46 is connected to the COD detector 88 and the electrolytic cell A11 via a combination of pump 100 and solid-liquid separator 25. The electrolytic cell A11 is connected to the feed port 77 of the sedimentation reaction tank 74 via valve 89 and pump 101. Then the sedimentation reaction tank 74 is connected to the solid-liquid separator 26 and the temporary storage tank 31 in sequence.

[0135] The precipitation reaction tank 74 is equipped with an oxidation-reduction potentiometer 22 and a detection device 64, and is also equipped with a feed port 77, a feed port 78 and a circulating liquid flow agitator 40; the temporary storage tank 32 and the liquid spray device 54 form a waste gas treatment combination; the detection device 63 is a hydrometer and the detection device 64 is a pH meter.

[0136] The iron-containing salt solution 85, containing heavy metal ion impurities, first flows into the oil-water separator 46. After oil removal treatment, the solution passes through the solid-liquid separator 25, the COD detector 88, and the feed inlet 76 before flowing into the electrolytic cell A11. The COD detector 88 detects the concentration of organic matter in the liquid flowing into the electrolytic cell A11. When the detection result is higher than the process set value, an alarm is issued, requiring the solid-liquid separator 25 to replace the filter medium to improve the filter medium's adsorption performance of oily substances. The electrolytic cell A11 is equipped with an anode 12 with a titanium basket, a cathode 14, a redox potentiometer 21, a detection device 63, and a circulating liquid flow stirrer 39. The top of the cathode area of ​​the electrolytic cell A11 is also equipped with a tank cover exhaust hood or exhaust pipe 59 and a feed inlet 76. The tank cover exhaust hood or exhaust pipe 59 is used to extract hydrogen, acid gas, hydrogen sulfide gas, and ammonia nitrogen gas produced during the production process. The solid feeding machine 43 is installed on top of the titanium basket anode 12. The solid feeding machine 43 contains metal iron fragments or iron powder. During the reaction process, iron metal or iron powder is added to the titanium basket of the electrolytic cell A with titanium basket anode 12 according to the process requirements.

[0137] After the electrolytic power supply 86 is connected to the anode and cathode of electrolytic cell A, the iron metal in the titanium basket acts as a soluble anode and participates in the electrochemical reaction of electrolytic cell A, dissolving in the solution. During the reaction, the data detected by the redox potentiometer 21 and the detection device 63 are reflected by the instruments, allowing the operator to adjust the output current of the electrolytic power supply or shut it down according to the process requirements, and to add acidic substances to maintain the electrochemical reaction. When the required iron ion concentration is reached, the valve 89 is opened and the pump 101 is started, pumping the electrolyte from electrolytic cell A into the precipitation reaction tank 74 through the feed port 77. In the precipitation reaction tank 74, heavy metal ion removal is performed. During the process, alkaline substances and oxalate aqueous solutions are added sequentially through the feed port 78. After filtration by the solid-liquid separator 26, the iron-containing salt solution that has been de-metallized is temporarily stored in the temporary storage tank 31.

[0138] In this embodiment, the iron-containing salt solution 85 containing heavy metal ion impurities to be treated is an acidic aqueous solution with ferric chloride as the main component, wherein the heavy metal impurity component is chromium, and the solution also contains a small amount of nitric acid.

[0139] This embodiment 4 is performed according to the following steps:

[0140] (1) The iron salt solution 85 containing heavy metal ion impurities is poured into the water-oil separator 46. After the oil layer is separated, the solution is pressurized by the pump 100 and flows into the solid-liquid separator 25. Then it flows into the COD detector 88 and flows into the electrolytic cell A through the feed port 76 connected to the pipeline outlet.

[0141] (2) The iron metal contained in the solid feeding machine 43 is fed into the electrolytic cell A with titanium basket anode 12 according to the process requirements. The iron ion concentration in the iron-containing salt solution 85 containing heavy metal ion impurities is increased through the iron dissolution reaction. At the same time, acidic substances are added to the electrolytic cell A according to the process to maintain the chemical reaction of electrolytic iron dissolution. When the process requirement of iron concentration of 400 g / L is reached, the solution is pumped to the precipitation reaction tank 74.

[0142] (3) Sodium chlorate is added to the precipitation reaction tank 74 through the feeding port 78, and oxygen and air are introduced through the pipeline (the ratio of each component added is 5:1:1). Hydrochloric acid is also added according to the detection device 64, so that the ferrous ions in the solution in the tank are oxidized to ferric ions. At the same time, some heavy metal ions in the solution are also oxidized to higher valence heavy metal ions. During the reaction, the acidity is controlled by the detection device 64, and the mixture is continuously stirred and the oxidation-reduction potentiometer is used for feedback process control until the oxidation-reduction potential of the solution reaches the oxidation process requirements.

[0143] (4) After the oxidation reaction is completed, iron powder reducing agent is added to the precipitation reaction tank 74 through the feed port 78. The amount added is measured according to the reaction equivalence of the total heavy metal ion concentration and is appropriately excessive to bring the oxidation-reduction potential to the value shown in Table 1. The solution is then mixed by the circulating liquid flow stirrer 40 to reduce the heavy metal ions in the solution to the lowest valence state, thus preparing an iron-containing acidic solution A, which is mainly composed of ferric ions and contains the lowest valence state heavy metal ion impurities.

[0144] (5) Adjust the pH value of the iron-containing acidic solution A in the precipitation reaction tank 74, that is, add the sodium hydroxide and sodium bicarbonate solution required for the neutralization reaction (the ratio of each component is 1:1) to the iron-containing acidic solution A through the feed port 78 to raise the pH value by 1.6, and add a mixed aqueous solution of sodium oxalate and potassium oxalate (the ratio of each component is 2:1); at the same time, during the reaction, according to the pH value change of the solution being treated due to the addition of oxalate, add hydrochloric acid to maintain the original pH value of the solution, so that heavy metal oxalate precipitates that are insoluble in weak acid aqueous solution are generated in the solution.

[0145] (6) The solution in the precipitation reaction tank 74 is subjected to solid-liquid separation by the solid-liquid separator 26. The clear liquid obtained by separation is an iron-containing acidic solution with most of the heavy metal ions removed, and is temporarily stored in the temporary storage tank 31.

[0146] The steps of this embodiment are explained in detail as follows: In step (1), the iron-containing salt solution to be treated is de-oiled from the oil-water separator 46 and then enters the solid-liquid separator 25 via pump 100, and flows through the COD detector 88. The COD detector 88 samples and analyzes the solution in the pipeline. If the organic matter content of the solution is higher than the set value of the process requirements, the COD detector 88 issues an alarm and stops pump 100. The solid-liquid separator 25 continues to work only after the filter medium is replaced to improve the adsorption performance of organic matter. Step (2) uses the hydrometer in the detection device 63 to control the iron content in the electrolytic solution. During the iron dissolution process, hydrochloric acid is added according to the process requirements based on the pH meter in the detection device 63. During the chemical reaction, since iron metal contains trace amounts of sulfur, hydrogen sulfide gas will be released in the acidic solution. In addition, since the iron-containing salt acidic solution contains a small amount of nitric acid impurities, barium nitrate decomposes during the iron dissolution process to release nitrogen oxide gas. In the third step, the redox potential is controlled by a redox potentiometer, and the solution is controlled based on the redox potential value at a certain iron content. In step (4), an appropriate excess of reducing agent is added according to the reduction and valence reduction reaction equivalent of the total heavy metal ion impurities, so that the solution reacts to generate an acidic solution of iron salts, mainly composed of ferric ions and containing the lowest valence state ions of heavy metal impurities. In the fifth step, the main issues are the phenomenon of oxalate re-dissolving in acidic solutions and the low production yield caused by the precipitation of a large amount of ferric hydroxide when the pH of the solution is adjusted to too high. Therefore, acidic or alkaline substances need to be added to maintain the original pH value when the solution becomes turbid, so as to achieve the production objective of precipitation of heavy metal oxalate and reduction of ferric hydroxide precipitation.

[0147] The nitrogen oxide gas, sulfide gas, hydrogen gas, and acid gas produced in the electrolyte of electrolytic cell A, as well as the tail gas from precipitation reaction tank 74 and temporary storage tank 31, are all directed by liquid spray device 54 to a combined tail gas reaction device with temporary storage tank 32 for treatment. The tail gas is neutralized by a sodium hydroxide solution in temporary storage tank 32. The remaining gas after the chemical reaction is directly discharged through high-altitude hydrogen direct vent 72.

[0148] The removal process results of this embodiment are listed in Table 1.

[0149] Example 5

[0150] like Figure 5The image shown is also an embodiment of the present invention for removing heavy metal ion impurities from iron-containing salt solutions. The equipment used includes an electrolytic cell A11, an electrolytic cell A anode with a titanium basket 12, an insoluble anode 13, an electrolytic cell A cathode 14, an electrolytic cell B 15, an electrolytic cell B anode 16, an electrolytic cell B cathode 17, an electrolytic cell separator 18 for electrolytic cell B, oxidation-reduction potentiometers 21, 22, and 23, a solid-liquid separator 25, a temporary storage tank 31, a temporary storage tank 32, an impeller-type agitator 36, an impeller-type agitator 37, a circulating liquid flow agitator 39, a solid feeding mechanism 43, a vacuum jet injector 49, and a tank cover extractor. 58. Exhaust hood or extraction pipe; 59. Tank cover exhaust hood or extraction pipe; 60. Tank cover exhaust hood or extraction pipe; 63. Detection device; 64. Detection device; 65. Automatic detection and feeding controller; 71. Hydrogen direct vent; 72. Precipitation reaction tank; 74. Feeding port; 76. Feeding port; 77. Feeding port; 78. Tail gas discharge port; 81. Tail gas discharge port; 82. Iron-containing salt solution containing heavy metal ion impurities; 85. Electrolysis power supply; 86. Electrolysis power supply; 87. COD detector; 88. Valve; 89. Valve; 90. Valve; 91. Valve; 92. Valve; 93. Pump; 100. Pump; 101. Pump; 102. Pump; 103. Pump; 104. Among them:

[0151] Electrolytic cell A11 is connected to the feed port 77 of electrolytic cell B15 via valve 89, pump 100, and solid-liquid separator 25. Electrolytic cell B15 is connected to the feed port 78 of precipitation reaction tank 74 via pump 101 and valve 90. Then, precipitation reaction tank 74 is connected to solid-liquid separator 26 and temporary storage tank 31 in sequence via valve 92 and pump 103.

[0152] In this embodiment, the iron salt solution 85 containing heavy metal ion impurities to be treated is an acidic ferric sulfate solution, and its heavy metal impurity components are lead, cadmium, manganese, chromium, nickel, and zinc.

[0153] A sulfuric acid solution and a ferric sulfate solution are added to electrolytic cell A11 to prepare an iron-containing salt solution 85 containing heavy metal ion impurities. Electrolytic cell A11 is equipped with an electrolytic cell A with a titanium basket anode 12, an electrolytic cell A insoluble anode 13, an electrolytic cell A cathode 14, a redox potentiometer 21, a detection device 63, and a circulating liquid flow stirrer 39. An exhaust hood or exhaust pipe 57 is also installed on the top of the cathode area of ​​electrolytic cell A11. The detection device 63 is a pH meter, and the exhaust hood or exhaust pipe 57 is used to extract hydrogen, acid gas, and hydrogen sulfide gas produced during the production process. The solid feeding device 43 is installed on top of the titanium basket anode 12. The solid feeding device 43 contains metal iron fragments or iron powder. After the electrolysis power supply 86 is turned on and the circulating liquid flow agitator 39 is started, the solid feeding device 43 continuously adds iron metal into the titanium basket of the titanium basket anode 12 in the electrolysis cell A to carry out iron dissolution operation according to the process requirements.

[0154] The two anodes of electrolytic cell A are connected in parallel to the positive terminal of electrolytic power supply 86. The iron metal in the titanium basket acts as a soluble anode, participating in the electrochemical reaction of electrolytic cell A and dissolving in the solution. The insoluble anode 13 continuously oxidizes the ferrous ions in the electrolyte to ferric ions through an electrochemical oxidation reaction. The presence of ferric ions in the solution accelerates the iron dissolution reaction. During this process, the data detected by the redox potentiometer 21 and the detection device 63 are reflected by the instrument and transmitted to the automatic detection and feeding controller for processing. The controller then outputs instructions to the actuator to adjust the output current of the electrolytic power supply 86 or to shut it down, add acidic substances, and activate the solid feeding mechanism 43 to maintain the iron dissolution reaction. When the solution reaches the required iron ion concentration, the valve 89 is opened and the pump 100 is started, pumping the electrolyte from electrolytic cell A11 to electrolytic cell B15 through the feeding port 77.

[0155] Electrolytic cell B15 is divided into an anode tank area and a cathode tank area by an electrolytic cell separator 18, wherein the electrolytic cell separator 18 of electrolytic cell B is preferably an anion exchange membrane; the anode tank area is equipped with an anode 16 of electrolytic cell B, a redox potentiometer 23, a detection device 65, an impeller-type stirrer 37, and a feed port 77; the cathode tank area is equipped with a cathode 17 of electrolytic cell B, a redox potentiometer 22, a detection device 64, an impeller-type stirrer 36, and a feed port 76; the top of the anode tank area and the cathode tank area are respectively equipped with a tank cover exhaust hood or exhaust pipe 59 and a tank cover exhaust hood or exhaust pipe 58; wherein, the detection device 64 is a pH meter and the detection device 65 is a pH meter.

[0156] The solution processed by electrolytic cell A is added to the anode zone of electrolytic cell B15 through feed port 77 for oxidation reaction, which oxidizes the ferrous ions in the solution to ferric ions. The solution after oxidation reaction is pumped to feed port 76 through valve 90 and pump 101 and placed in the cathode zone for reduction reaction, which reduces the heavy metal ions in the solution to the lowest valence state, thus producing an iron-containing acidic solution A, which is mainly composed of ferric ions and contains heavy metal ion impurities in the lowest valence state.

[0157] Then, the iron-containing acidic solution A is pumped into the precipitation reaction tank 74. The precipitation reaction tank 74 is equipped with a feed port 78 and contains an oxidation-reduction potentiometer 24, a detection device 66, and an impeller-type stirrer 38. A tank cover and exhaust hood or exhaust pipe 60 are installed on top. The detection device 66 is a pH meter. During the treatment process in the precipitation reaction tank 74, alkaline substances and a mixed solution of oxalic acid and sodium oxalate are added sequentially through the feed port 78 to react and precipitate more precipitate. After filtration by the solid-liquid separator 26, the iron-containing salt solution, after heavy metal removal, is temporarily stored in a temporary storage tank 31. The temporary storage tank 31 is equipped with a detection device 67, which is a pH meter.

[0158] This embodiment 5 is performed according to the following steps:

[0159] (1) After mixing sulfuric acid and ferric sulfate solution containing heavy metal ions, the resulting iron salt solution 85 containing heavy metal ion impurities is poured into electrolytic cell A11.

[0160] (2) The automatic detection and feeding controller 71 performs automatic detection. After the detection of each process is ready, the electrolysis power supply 86 is turned on to carry out the operation.

[0161] (3) The iron metal installed in the solid feeding machine 43 is fed into the anode 12 with titanium basket in electrolytic cell A according to the process requirements. The iron concentration in the iron salt solution 85 containing heavy metal ion impurities is increased by dissolving the iron. At the same time, the data of the detection device 63 is transmitted to the automatic detection and feeding controller 71 for processing. Acidic substances are added to electrolytic cell A according to the process to maintain the chemical reaction of electrolytic iron dissolution. When the process requirement of iron concentration of 100g / L is reached, the solution in the electrolyte cell A is pumped to the anode area of ​​electrolytic cell B.

[0162] (4) The electrolysis power supply 87 is automatically switched on according to the program to carry out the oxidation reaction of the anolyte in electrolytic cell B, so that the ferrous ions in the solution in the cell are oxidized to ferric ions. At the same time, some heavy metal ions in the solution are also oxidized to higher valence heavy metal ions. During the reaction, the detection device 65 controls the acidity, and continuously stirs and uses the redox potentiometer 23 for automatic feedback process control until the redox potential value of the solution reaches the oxidation process requirement of 550mV, and then pumps it to the cathode area of ​​electrolytic cell B15.

[0163] (5) The solution undergoes an electrochemical reduction reaction in the cathode area of ​​electrolytic cell B15, so that its oxidation-reduction potential reaches the value shown in Table 1. At this time, the heavy metal ions in the solution are reduced to the lowest valence state heavy metal ions, and an iron-containing acidic solution A is prepared, which is mainly composed of ferric ions and contains the lowest valence state heavy metal ion impurities. The solution is then pumped into precipitation reaction tank 74.

[0164] (6) Adjust the pH value of the iron-containing acidic solution A in the precipitation reaction tank 74. Add the sodium hydroxide solution required for the neutralization reaction to the iron-containing acidic solution A through the feed port 78 to raise the pH value to 3.0. Then add a mixed aqueous solution of oxalic acid and sodium oxalate (the ratio of each component added is 2:1) and add sulfuric acid at the same time to maintain the original pH value of the solution so that heavy metal salt precipitates insoluble in weak acid aqueous solution are generated in the solution without generating too much iron hydroxide precipitate.

[0165] (7) The solution in the precipitation reaction tank 74 is subjected to solid-liquid separation by the solid-liquid separator 26. The clear liquid obtained by separation is the iron-containing acidic solution with most of the heavy metal ions removed, and it is temporarily stored in the temporary storage tank 31.

[0166] The steps of this embodiment are explained in detail as follows: In step (2), during the electrolysis and acid etching of the ferric sulfate acidic solution containing heavy metal ions, the iron metal contains ferric sulfide impurities which dissolve in the acid, resulting in lead sulfide and zinc sulfide precipitates in the solution. When the iron concentration reaches the process parameters, the solution is pressurized by pump 100 and processed by solid-liquid separator 25, and then pumped to the anode tank area of ​​electrolytic cell B15. Step (3) uses redox potentiometer 23 to control the oxidation process in the anode electrolyte of electrolytic cell B15. During the process, sulfuric acid is added according to the process requirements based on the pH meter in detection device 65. In the initial operation, dilute sulfuric acid is used as the cathode electrolyte of electrolytic cell B15. During the electrolysis operation, the acidity of the cathode electrolyte continuously decreases, while the acidity of the anode electrolyte continuously increases. After the anode electrolyte of electrolytic cell B15 is oxidized according to the process, it is pumped to the cathode tank area of ​​electrolytic cell B15 according to the procedure. In step (4), the solution undergoes an electrochemical reduction reaction in the cathode tank. During this process, the data detected by the redox potentiometer 22 is transmitted to the automatic detection and feeding controller 71. The solution is controlled based on the redox potential value at a certain iron content. In the reduction and valence reduction reaction of heavy metal ion concentration impurities, an iron-containing acidic solution A is generated, which is mainly composed of ferric ions and contains the lowest valence state ions of heavy metal impurities. In step (5), in order to solve the phenomenon of heavy metal oxalate re-dissolving in acidic solution and to avoid the pH value of the solution being adjusted too high, resulting in a large amount of ferric hydroxide precipitation and low production yield, sulfuric acid is added to maintain the original pH value of the solution at just the point of turbidity. This achieves the production objective of precipitating heavy metal oxalate as much as possible while reducing the precipitation of ferric hydroxide.

[0167] The tail gases of sulfide gas, hydrogen gas, and acid gas produced in the electrolyte of electrolytic cell A11, the acid gas and hydrogen gas produced in electrolytic cell B15, and the tail gases of precipitation reaction tank 74 and temporary storage tank 31 are all drawn by their respective tank covers and exhaust hoods or exhaust pipes to the combined tail gas reaction device of vacuum jet 49 and temporary storage tank 32 for treatment. The tail gases are neutralized by the sodium hydroxide solution in temporary storage tank 32. The remaining gas after the chemical reaction is directly discharged through high-altitude hydrogen direct exhaust device 72.

[0168] The removal process results of this embodiment are listed in Table 1.

[0169] Comparative Example 1

[0170] In this comparative example, the iron salt solution containing heavy metal ion impurities to be treated is the same as in Example 5, which is an acidic ferric sulfate solution, and the heavy metal impurity components are lead, cadmium, manganese, chromium, nickel, and zinc.

[0171] Iron was added to an iron-containing salt solution containing heavy metal ion impurities until no more nickel was reduced and precipitated. The resulting solution was then mixed with sodium hydroxide solution until the pH reached 6. After solid-liquid separation, the resulting solution was tested.

[0172] The removal process results for this comparative example are listed in Table 2.

[0173] Comparative Example 2

[0174] In this comparative example, the iron salt solution containing heavy metal ion impurities to be treated is the same as in Example 1, which is an aqueous solution with ferrous chloride and ferrous sulfate as the main components, and the heavy metal impurities are mainly chromium and nickel.

[0175] A solution containing iron salts and heavy metal ion impurities was mixed with a sodium hydroxide solution until the pH reached 8. After solid-liquid separation, the resulting solution was tested.

[0176] The removal process results for this comparative example are listed in Table 2.

[0177] Table 1

[0178]

[0179] Table 2

[0180]

[0181] As can be seen from the above results, the iron ion loss rate of Examples 1-5 is much lower than that of Comparative Examples 1 and 2, and the ratio of heavy metal content to iron content after treatment in Examples 1-5 is also much lower than that in Comparative Examples 1 and 2. Since the usage of iron salt products in various fields is calculated based on the amount of iron, a higher ratio of heavy metal content to iron content means more heavy metal impurities are introduced when using the same amount of iron. Therefore, the method of the present invention can effectively improve the problems of iron ion loss and heavy metal impurity concentration in the prior art.

[0182] This invention can be summarized in other specific forms that do not depart from the spirit or main features of the invention. The above embodiments of the invention are merely illustrative and not restrictive. Therefore, any minor modifications, equivalent variations, and alterations made to the above embodiments based on the essential technology of this invention fall within the scope of the invention's technical solution.

Claims

1. A method for removing heavy metal ion impurities from an iron-containing salt solution, characterized in that, Includes the following steps: Step 1: The iron-containing salt solution to be treated is oxidized by adding an oxidant and / or by electrochemical methods to obtain an iron-containing acidic solution A; Alternatively, the iron-containing salt solution to be treated can be oxidized by adding an oxidant and / or by electrochemical methods, and then reduced by adding a reducing agent and / or by electrochemical methods to obtain an iron-containing acidic solution A; The redox potential of the iron-containing acidic solution A is 100-700 mV; Step 2: Add oxalic acid and / or oxalate to the iron-containing acidic solution A obtained in Step 1, mix them, and let the heavy metal ion impurities in the solution react chemically to form a precipitate of heavy metal impurity oxalate. During the reaction, ensure that the pH value of the mixture is within the range of 0.5-3. Then, the solid-liquid mixture obtained after the reaction is subjected to solid-liquid separation treatment.

2. The method for removing heavy metal ion impurities from iron-containing salt solutions according to claim 1, characterized in that, The oxidizing agent is selected from one or more of hydrogen peroxide, sodium perchlorate, potassium perchlorate, sodium chlorate, potassium chlorate, sodium hypochlorite, calcium hypochlorite, sodium chlorite, sodium dichromate, potassium dichromate, sodium percarbonate, potassium percarbonate, potassium permanganate, sodium perborate, potassium perborate, sodium persulfate, potassium persulfate, ammonium persulfate, chlorine, ozone, oxygen, and air; the reducing agent is selected from one or more of ferrous metal, ferrous sulfate, ferrous chloride, ferrous hydroxide, sodium sulfite, and sodium bisulfite.

3. The method for removing heavy metal ion impurities from iron-containing salt solutions according to claim 2, characterized in that, In step one, an electrolytic cell B is used to oxidize the iron-containing salt solution to be treated by an electrochemical method. The electrolytic cell B includes an insoluble anode, an insoluble cathode, an electrolytic cell separator, and an electrolytic power source. The electrolytic cell B is divided into an anode tank area and a cathode tank area by the electrolytic cell separator. The insoluble anode of electrolytic cell B is selected from one or more of conductive graphite, titanium-based coated electrodes, gold, platinum, and alloys containing the above metals; the insoluble cathode of electrolytic cell B is selected from one or more of conductive graphite, stainless steel, gold, platinum, silver, copper, iron, nickel, tin, zinc, aluminum, titanium, and alloys containing the above metals; the electrolytic cell separator of electrolytic cell B is a material that can effectively prevent metal cations from migrating from the anode area to the cathode area of ​​electrolytic cell B during operation, specifically selected from one or more of anion exchange membranes, bipolar membranes, reverse osmosis membranes, and neutral filter membranes; the anolyte of electrolytic cell B is an iron-containing salt solution to be treated, and the catholyte of electrolytic cell B is an aqueous electrolyte solution.

4. The method for removing heavy metal ion impurities from iron-containing salt solutions according to claim 3, characterized in that, In step one, when the iron-containing salt solution to be treated is oxidized and then reduced by adding a reducing agent and / or by using an electrochemical method, the concentration of heavy metal ion impurities in the iron-containing salt solution to be treated or the oxidized iron-containing salt solution to be treated is detected and measured. Based on the detection results, a reducing agent is added to the oxidized iron-containing salt solution to be treated to completely reduce the high-valence heavy metal ions to the lowest valence state, thus obtaining an iron-containing acidic solution A.

5. The method for removing heavy metal ion impurities from iron-containing salt solutions according to claim 4, characterized in that, In step one, after oxidizing the iron-containing salt solution to be treated, an electrochemical reduction reaction is carried out. The oxidized iron-containing salt solution to be treated is added to the cathode area of ​​the electrolytic cell B for reduction, so that the high-valence heavy metal ion impurities in the solution are reduced to low-valence heavy metal ions, resulting in an iron-containing acidic solution A. The electrolytic cathode material of the electrolytic cell B is selected from one or more of conductive graphite, gold, platinum, silver, titanium, iron, alloys containing the above metals, and stainless steel.

6. The method for removing heavy metal ion impurities from iron-containing salt solutions according to claim 5, characterized in that, The oxalate mentioned in step two is sodium oxalate and / or potassium oxalate.

7. The method for removing heavy metal ion impurities from iron-containing salt solutions according to claim 6, characterized in that, The alkaline substance used to adjust the pH value in step two is selected from at least one of sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, potassium carbonate, and potassium bicarbonate.

8. The method for removing heavy metal ion impurities from iron-containing salt solutions according to any one of claims 1-7, characterized in that, Sulfide is added to the iron-containing acidic solution A obtained in step one. The resulting precipitate is removed by solid-liquid separation before proceeding to step two, or it is removed by solid-liquid separation in step two. The sulfide is at least one selected from sodium sulfide, potassium sulfide, and hydrogen sulfide.

9. An apparatus suitable for the method of removing heavy metal ion impurities from iron-containing salt solutions as described in claim 1, characterized in that, It includes a chemical reaction tank, a redox potentiometer, a stirring device, a solid-liquid separator, and a temporary storage tank; among which: The chemical reaction tank is used for at least one of the following treatment steps: oxidation treatment of the iron-containing salt solution to be treated, reduction treatment of the oxidized iron-containing salt solution to be treated, and chemical reaction precipitation treatment of iron-containing acidic solution A with oxalic acid and / or oxalate. The redox potentiometer is used for detection and control according to process requirements during the oxidation and / or reduction treatment of the iron-containing salt solution to be treated; the solid-liquid separator is used for solid-liquid separation of the precipitate that appears in the solution after the chemical reaction in the tank; the temporary storage tank is used for temporary storage of the clear liquid obtained after filtration by the solid-liquid separator.

10. The device according to claim 9, characterized in that, An additional electrolytic cell B is added and connected to a chemical reaction cell for oxidation and / or reduction treatment of the iron-containing salt solution to be treated. In electrolytic cell B, a redox potentiometer is used to detect process data and control the oxidation and / or reduction reactions.

11. The device according to claim 10, characterized in that, The electrolytic cell B is divided into an electrolytic anode cell and an electrolytic cathode cell by an electrolytic cell separator; the electrolytic cell separator is at least one of anion exchange membrane, bipolar membrane, reverse osmosis membrane and neutral filter membrane. The electrolytic anode of the electrolytic cell B is made of one or more of the following materials: conductive graphite, titanium-based coated electrode, gold, platinum, and gold / platinum alloy; the electrolytic cathode of the electrolytic cell B is made of one or more of the following materials: conductive graphite, gold, platinum, silver, titanium, gold / platinum / silver / titanium alloy, stainless steel, and iron.

12. The device according to claim 11, characterized in that, An electrolytic cell A is added, and the mixture after being treated in electrolytic cell A is sent to a chemical reaction tank and / or electrolytic cell B for further processing; the electrolytic anode of electrolytic cell A is a soluble anode of iron; the electrolytic cathode is at least one selected from conductive graphite, stainless steel, gold, platinum, silver, copper, iron, titanium and alloys of the above metals, as an insoluble cathode.

Images