Clean production process for recycling nickel-containing waste

Abstract

The invention discloses a clean production process for cyclic utilization of nickel-containing waste, which comprises the following steps: placing nitrogen trifluoride electrolysis nickel-containing waste residue in an electrothermal furnace, sublimating or decomposing ammonium bifluoride in the nickel-containing waste residue, condensing, liquefying and crystallizing through a condensing system to re-synthesize ammonium bifluoride for sale or reuse; the main components of the material a heated and volatilized by the electrothermal furnace are nickel fluoride, ferric fluoride and copper fluoride; adding the material a into an alkaline material solution for conversion leaching to obtain nickel hydroxide, ferric hydroxide and copper hydroxide, and converting a sodium hydroxide or potassium hydroxide solution into a sodium fluoride or potassium fluoride solution; adding an acid-carrying anolyte of a nickel electrolysis system into the obtained nickel hydroxide, ferric hydroxide and copper hydroxide slag, dissolving nickel hydroxide, ferric hydroxide and copper hydroxide into an electrolyte by using acid in the anolyte, removing metal impurities, and filtering to obtain a pure nickel electrolysis pre-solution; and electrolytic nickel with the nickel content larger than 99.96% of Ni is produced through insoluble anode electrolysis.

Description

Technical Field

[0001] The invention relates to the field of harmless treatment of nickel-containing hazardous waste, and in particular to a clean production process for recycling nickel-containing waste. Background Art

[0002] High-purity nitrogen trifluoride is an excellent plasma etching gas in the microelectronics industry and an essential material in the semiconductor LCD industry manufacturing process. It is mostly used as an etchant for semiconductor materials such as polysilicon and silicon nitride in the electronics industry, especially for etching integrated circuit materials with a thickness of less than 1.5μm; it can also play a cleaning role in the production of integrated circuit boards and liquid crystal displays, and is also used as a fluorine source for hydrogen fluoride and fluorine gas high-energy chemical lasers.

[0003] The production of high-purity nitrogen trifluoride is mostly prepared by ammonium bifluoride molten salt electrolysis. During the electrolysis process, the metal nickel plate as the anode is gradually dissolved, and the iron plate, which is usually used as the cathode, will also be slowly corroded and deposited at the bottom of the electrolytic cell in the form of nickel fluoride, ferric fluoride, copper fluoride, and corroded metal nickel slag and metal iron slag. Therefore, the sediment in the electrolytic cell must be cleaned regularly to maintain the smooth progress of electrolysis. The cleaned sediment is the electrolytic waste slag. In addition to nickel fluoride, ferrous fluoride, metal nickel slag, metal iron slag, etc., the electrolytic waste slag also carries a large amount of ammonium bifluoride. Nickel, as a precious metal, has a high economic value. If it is not recycled, it will cause waste and serious heavy metal pollution; the large amount of ammonium bifluoride carried in the electrolytic waste slag has fluorine and ammonia nitrogen as its characteristic pollutants. Fluorine is highly toxic, and ammonia nitrogen is also a serious pollutant. If it is not recycled, it will also cause serious environmental damage.

[0004] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a clean production process for comprehensive recovery of multiple metals and multiple elements in nickel-containing waste slag generated in the production process of nitrogen trifluoride, which can effectively produce nickel into high-purity electrolytic nickel for reuse in the production system, and at the same time convert the combined waste of fluorine and ammonia in the slag into raw materials that can be reused in the production process, thereby truly realizing a circular economy and a green and clean production process.

[0005] In view of this, this application is hereby filed. Summary of the invention

[0006] The purpose of the present invention is to provide a clean production process for the comprehensive recovery of multiple metals and multiple elements in nickel-containing waste slag generated in the production process of nitrogen trifluoride, which can effectively produce nickel into high-purity electrolytic nickel for reuse in the production system, and at the same time convert the combined waste of fluorine and ammonia in the slag into raw materials that can be reused in the production process, thereby truly realizing a circular economy and a green and clean production process.

[0007] The embodiment of the present invention is achieved as follows:

[0008] A clean production process for recycling nickel-containing waste, the clean production process comprising the following steps:

[0009] S1: placing the nickel-containing waste slag produced by the electrolysis of nitrogen trifluoride in an electric heating furnace for heating; controlling the temperature to 230-600°C;

[0010] S2: Sublime or decompose the ammonium bifluoride in the nickel-containing waste slag, condense, liquefy and crystallize through a condensation system to re-synthesize the ammonium bifluoride for sale or reuse;

[0011] S3: The unsynthesized hydrogen fluoride in S2 is absorbed by tail gas water to increase its concentration, and commercial hydrofluoric acid is obtained for sale or reuse;

[0012] S4: The main components of material a after volatilization treatment by heating in an electric furnace are nickel fluoride, iron fluoride and copper fluoride; material a is added to an alkaline material solution for conversion and leaching, and nickel fluoride, iron fluoride and copper fluoride are converted into nickel hydroxide, iron hydroxide and copper hydroxide, and sodium hydroxide or potassium hydroxide solution is converted into sodium fluoride or potassium fluoride solution; then evaporation is performed to obtain sodium fluoride or potassium fluoride crystal products for sale;

[0013] S5: adding the acidic anolyte of the electrolytic nickel system to the nickel hydroxide, iron hydroxide and copper hydroxide slag obtained in S4, dissolving the nickel hydroxide, iron hydroxide and copper hydroxide in the electrolyte by using the acid in the anolyte, adding acid to the insufficient acid, and then removing metal impurities. After completion, filtering the reaction slurry to obtain a pure nickel pre-electrolysis solution;

[0014] S6: The obtained pure nickel electrolytic pre-liquid is electrolyzed by insoluble anode to produce electrolytic nickel containing more than Ni99.96%.

[0015] In one implementation, the metal impurity removal process in step S5 is as follows: after filtering the solution, adding a copper removal agent a to replace copper to form metal copper powder and filtering it; then adding an oxidant to the filtrate to control the pH of the solution to 3-5, and removing the iron in the solution to form iron hydroxide; filtering the reaction slurry to obtain a pure nickel pre-electrolysis solution; the chemical equation of the reaction process is as follows:

[0016] Ni(OH)2+H2SO4=NiSO4+2H2O

[0017] Cu(OH)2+H2SO4=CuSO4+2H2O

[0018] Fe(OH)2+H2SO4=FeSO4+2H2O

[0019] CuSO4+Fe=Cu+FeSO4

[0020] 2Fe 2+ +H2O2+4OH- =2Fe(OH)3.

[0021] In one implementation, the metal impurity removal process in step S5 is as follows: adding an oxidant to control the pH of the solution to 3-5, removing the iron in the solution to form iron hydroxide; adding a copper removal agent b to precipitate copper after filtering the solution to form copper sulfide precipitation; filtering the reaction slurry to obtain a pure nickel pre-electrolysis solution; the chemical equation of the reaction process is as follows:

[0022] Ni(OH)2+H2SO4=NiSO4+2H2O

[0023] Cu(OH)2+H2SO4=CuSO4+2H2O

[0024] Fe(OH)2+H2SO4=FeSO4+2H2O

[0025] CuSO4+NiS=CuS+NiSO4

[0026] CuSO4+Na2S=CuS+Na2SO4

[0027] 2Fe 2+ +H2O2+4OH - =2Fe(OH)3.

[0028] In one implementation, in step S1, the electric heating furnace is an industrial frequency furnace, a medium frequency furnace, a resistance furnace, an induction furnace, an arc furnace, a plasma furnace, an electron beam furnace, and an electric steam boiler.

[0029] In one implementation, in step S3, in the process of increasing the concentration by absorbing the tail gas water to obtain commercial hydrofluoric acid for sale or reuse, the temperature of the tail gas water is controlled at 10-50°C and the flow rate of the tail gas water is controlled at 0.5-1.0 m / s.

[0030] In one implementation, in step S4, the alkaline material solution is any one of sodium hydroxide or potassium hydroxide.

[0031] In one implementation, the copper removal agent a is iron powder. In the process of replacing copper to form metallic copper powder and filtering, the amount of copper removal agent added is controlled to be 1.05 to 1.2 times the molar amount of copper ions in the solution; excess iron is removed by oxidation precipitation with hydrogen peroxide, wherein the oxidant is hydrogen peroxide.

[0032] In one implementation, the added oxidant is hydrogen peroxide, and the copper removal agent b is any one of nickel sulfide or sodium sulfide.

[0033] In one implementation, the insoluble anode for electrolysis is a resistant or titanium-coated iridium-ruthenium anode, and the cathode is a metal titanium plate. A nickel starting plate is first produced, and then the nickel starting plate is used as the cathode to produce Ni99.96% electrolytic nickel.

[0034] In one implementation, in step S6, the pure nickel pre-electrolysis solution is electrolyzed by an insoluble anode to produce electrolytic nickel containing more than 99.96% nickel, and the current density of the electrolysis is controlled at 0.1-0.5A / dm 2 , the electrolysis voltage is controlled at 2.0-3.0V.

[0035] The beneficial effects of the technical solution of the embodiment of the present invention include:

[0036] A clean production process for recycling nickel-containing waste provided by an embodiment of the present invention, the clean production process of the present invention can effectively recycle nickel in nickel-containing waste slag, produce it as high-purity electrolytic nickel, and reuse it in the production system. At the same time, the process can also convert the chemical waste of fluorine and ammonia in the slag into raw materials that can be reused in the production process, realizing circular economy and green clean production. This not only improves the utilization efficiency of resources and reduces the generation of waste, but also reduces production costs and improves economic benefits. In addition, the process also helps to reduce environmental pollution, protect the environment, and conform to the concept of sustainable development. Therefore, the clean production process of the present invention has a wide range of application prospects and important practical value.

[0037] Overall:

[0038] (1) The present invention utilizes an electric heating furnace to heat nickel-containing waste slag to sublime or decompose ammonium bifluoride therein, and resynthesizes ammonium bifluoride through a condensation system, or increases the concentration through tail gas water absorption to obtain hydrofluoric acid, thereby realizing the recycling of fluorine, reducing fluorine emission and pollution, and also saving raw material costs;

[0039] (2) The present invention utilizes an alkaline material solution to convert nickel fluoride, iron fluoride and copper fluoride in nickel-containing waste slag into nickel hydroxide, iron hydroxide and copper hydroxide, and simultaneously generates a sodium fluoride or potassium fluoride solution, which is evaporated to obtain a sodium fluoride or potassium fluoride crystal product, thereby achieving further recovery and utilization of fluorine and also increasing the income of by-products;

[0040] (3) The present invention utilizes the acidic anolyte of the electrolytic nickel system to dissolve nickel hydroxide, iron hydroxide and copper hydroxide in the electrolyte, removes metal impurities, obtains a pure nickel pre-electrolysis solution, and produces high-purity electrolytic nickel through insoluble anode electrolysis, thereby achieving efficient recovery and utilization of nickel and improving product quality;

[0041] (4) The present invention adopts a variety of copper removal agents and oxidants, and the most suitable method can be selected according to the actual situation, thereby realizing the recovery and utilization of copper and avoiding the influence of copper on nickel electrolysis;

[0042] (5) During the entire process of the present invention, no harmful waste is generated, achieving zero waste discharge, meeting the requirements of clean production, and having good environmental and social benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] 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.

[0044] Figure 1 A flow chart of a clean production process embodiment 1 for recycling nickel-containing waste provided by an embodiment of the present invention;

[0045] Figure 2 A flow chart of Example 2 of a clean production process for recycling nickel-containing waste provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0047] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0048] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0049] The terms “first”, “second”, etc. are only used for distinguishing descriptions and should not be understood as indicating or implying relative importance.

[0050] In addition, the terms "parallel", "vertical", etc. do not mean that the components must be absolutely parallel or vertical, but can be slightly tilted. For example, "parallel" only means that its direction is more parallel than "vertical", and does not mean that the structure must be completely parallel, but can be slightly tilted.

[0051] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0052] Please refer to Figure 1-2 The present embodiment provides a clean production process for recycling nickel-containing waste, and the clean production process comprises the following steps:

[0053] S1: Place the nickel-containing waste slag from the electrolysis of nitrogen trifluoride in an electric furnace for heating; control the temperature at 230-600°C; due to the difference in melting point and boiling point, the ammonium bifluoride contained in the nickel waste slag sublimates or decomposes under high temperature; in this step, the main purpose of this step is to convert the solid ammonium bifluoride into gaseous state, providing raw materials for subsequent recycling, so as to facilitate subsequent treatment and recycling. At the same time, it also reduces the fluorine content of the nickel-containing waste slag and reduces the harm of fluorine to the environment. The reaction is as follows:

[0054] NH4HF2(solid)=NH4HF2(gas)+NH3 ↑ +2HF ↑

[0055] S2: Sublime or decompose the ammonium bifluoride in the nickel-containing waste residue, condense, liquefy and crystallize it through a condensation system to synthesize ammonium bifluoride for sale or reuse; condense, liquefy and crystallize the sublimated or decomposed ammonium bifluoride through a condensation system to synthesize ammonium bifluoride again. The ammonium bifluoride product that can be used for industrial production is obtained, realizing the recycling of fluorine, reducing the generation of waste and environmental pollution, saving resources and increasing profits.

[0056] S3: The unsynthesized hydrogen fluoride in S2 is absorbed by tail gas water to increase its concentration, and commercial hydrofluoric acid is obtained for sale or reuse. By recovering hydrogen fluoride, hydrofluoric acid products that can be used for industrial production are obtained, thus realizing the recycling of fluorine to reduce waste generation and environmental pollution.

[0057] S4: The main components of material a after heating and volatilization in an electric furnace are nickel fluoride, iron fluoride and copper fluoride; material a is added to an alkaline material solution for conversion and leaching, and nickel fluoride, iron fluoride and copper fluoride are converted into nickel hydroxide, iron hydroxide and copper hydroxide, and sodium hydroxide or potassium hydroxide solution is converted into sodium fluoride or potassium fluoride solution; then evaporate to obtain sodium fluoride or potassium fluoride crystal products for sale; its main purpose is to convert valuable metal ions (such as nickel, iron and copper) in waste residue into a recyclable form. The chemical equation of the conversion process reaction is as follows:

[0058] NiF2+2NaOH=2NaF+Ni(OH)2

[0059] NiF2+2KOH=2KF+Ni(OH)2

[0060] CuF2+2NaOH=2NaF+Cu(OH)2

[0061] CuF2+2KOH=2KF+Cu(OH)2

[0062] FeF2+2KOH=2KF+Fe(OH)2

[0063] S5: adding the acidic anolyte of the electrolytic nickel system to the nickel hydroxide, iron hydroxide and copper hydroxide slag obtained in S4, dissolving the nickel hydroxide, iron hydroxide and copper hydroxide in the electrolyte by using the acid in the anolyte, adding acid to the insufficient acid, and then removing metal impurities. After completion, filtering the reaction slurry to obtain a pure nickel pre-electrolysis solution;

[0064] More specifically, when the metal impurity removal step is selected, further, the metal impurity removal process in step S5 is: after the solution is filtered, a copper removal agent a is added to replace copper to form metal copper powder and filter it; then an oxidant is added to the filtrate to control the pH of the solution at 3 to 5, and the iron in the injection solution is removed by forming iron hydroxide; the reaction slurry is filtered to obtain a pure nickel pre-electrolysis solution; the chemical equation of the reaction process is as follows:

[0065] Ni(OH)2+H2SO4=NiSO4+2H2O

[0066] Cu(OH)2+H2SO4=CuSO4+2H2O

[0067] Fe(OH)2+H2SO4=FeSO4+2H2O

[0068] CuSO4+Fe=Cu+FeSO4

[0069] 2Fe 2+ +H2O2+4OH - =2Fe(OH)3.

[0070] S6: The obtained pure nickel electrolytic pre-liquid is electrolyzed by insoluble anode to produce electrolytic nickel containing more than Ni99.96%.

[0071] By adopting the above-mentioned process, the clean production process of the present invention can effectively recycle nickel in nickel-containing waste slag, produce it into high-purity electrolytic nickel, and reuse it in the production system. At the same time, the process can also convert the chemical waste of fluorine and ammonia in the slag into raw materials that can be reused in the production process, thereby realizing circular economy and green clean production. This not only improves the utilization efficiency of resources and reduces the generation of waste, but also reduces production costs and improves economic benefits. In addition, the process also helps to reduce environmental pollution, protect the environment, and conform to the concept of sustainable development. Therefore, the clean production process of the present invention has a wide range of application prospects and important practical value.

[0072] Through the above process, valuable elements such as nickel, fluorine and ammonia in nickel-containing waste slag can be efficiently recycled and utilized, the utilization efficiency of resources can be improved, the generation of waste can be reduced, the production cost can be reduced, and the economic benefits can be improved; the recycling of fluorides such as ammonium bifluoride, hydrofluoric acid, sodium fluoride or potassium fluoride can be achieved, the harm of fluorine to the environment can be reduced, the environment can be protected, and it is in line with the concept of sustainable development; the acid-containing anode liquid of the electrolytic nickel system can be reused, the consumption of acid can be saved, and the cost can be reduced.

[0073] Furthermore, the metal impurity removal process in step S5 is as follows: adding an oxidant to control the pH of the solution at 3 to 5, and removing the iron in the solution by forming iron hydroxide; using an oxidant (such as hydrogen peroxide) to oxidize the iron ions in the solution to form water-insoluble iron hydroxide precipitates, thereby achieving iron removal. By controlling the pH value of the solution, the generation and precipitation of iron hydroxide is guaranteed to avoid the generation of water-soluble iron salts; after the solution is filtered, copper removal agent b is added to precipitate copper to form copper sulfide precipitates; copper removal agent b (such as sodium sulfide, nickel sulfide) is used to reduce the copper ions in the solution to form water-insoluble copper sulfide precipitates, thereby achieving copper removal; filtering the reaction slurry to obtain a pure nickel pre-electrolysis solution; using a filtration method to separate insoluble impurities such as iron hydroxide and copper sulfide in the solution to obtain a clear solution containing nickel ions as a pre-treatment solution for electrolytic nickel; the chemical equation of the reaction process is as follows:

[0074] Ni(OH)2+H2SO4=NiSO4+2H2O

[0075] Cu(OH)2+H2SO4=CuSO4+2H2O

[0076] Fe(OH)2+H2SO4=FeSO4+2H2O

[0077] CuSO4+NiS=CuS+NiSO4

[0078] CuSO4+Na2S=CuS+Na2SO4

[0079] 2Fe 2+ +H2O2+4OH - =2Fe(OH)3.

[0080] Further, in step S1, the electric heating furnace is an industrial frequency furnace, a medium frequency furnace, a resistance furnace, an induction furnace, an electric arc furnace, a plasma furnace, an electron beam furnace and an electric steam boiler.

[0081] Further, in step S3, in the process of increasing the concentration by absorbing the tail gas water and obtaining the commercial hydrofluoric acid for sale or reuse, the temperature of the tail gas water is controlled at 10-50°C, and the flow rate of the tail gas water is controlled at 0.5-1.0m / s. Specifically, the interaction between the aqueous solution and the gas is used to transfer the hydrogen fluoride in the gas to the aqueous solution, thereby realizing the recovery and purification of hydrogen fluoride. Throughout the process, in order to ensure the absorption efficiency and stability of the tail gas water, avoid overheating or overcooling of the tail gas water, and affect the solubility and reaction rate of hydrogen fluoride; the temperature of the tail gas water is controlled at 10-50°C. Generally speaking, the lower the temperature of the tail gas water, the higher the solubility of hydrogen fluoride and the higher the absorption efficiency, but too low a temperature will cause the viscosity of the tail gas water to increase, the flow resistance to increase, the flow rate to decrease, the reaction rate to decrease, and the absorption efficiency to decrease. Therefore, in the actual production process, according to the properties of the tail gas water and the composition of the tail gas, the temperature range suitable for the above-mentioned specified temperature is selected to achieve the best absorption effect. In addition, in order to ensure sufficient contact and mass transfer between tail gas water and gas, improve the absorption efficiency and uniformity of tail gas water, avoid stagnation or eddy current of tail gas water, and affect the transfer and reaction of hydrogen fluoride. The flow rate of tail gas water is controlled at 0.5-1.0m / s. It is found in the production process that the higher the flow rate of tail gas water, the greater the turbulence between gas and liquid, the higher the mass transfer coefficient, and the higher the absorption efficiency. However, too high a flow rate will lead to increased pressure loss of tail gas water, increased energy consumption, unstable flow, and reduced absorption efficiency. Therefore, it is also necessary to select a suitable flow rate range according to the properties of tail gas water and the flow rate of tail gas to achieve the best absorption effect. In short, the method of using this process has simple structure, low energy consumption, high purification efficiency and wide application range. It can effectively remove water-soluble gases such as hydrogen fluoride gas (HF), hydrogen chloride gas (HCl), ammonia (NH3), sulfuric acid mist (H2SO4), chromic acid mist (CrO3), and hydrocyanic acid gas (HCN). The purified acid mist waste gas meets the national emission standards.

[0082] In summary, in step S3, the concentration is increased by absorbing the tail gas water to obtain the commercial hydrofluoric acid for sale or reuse, which realizes the efficient recycling of hydrogen fluoride, saves resources and increases profits. At the same time, it also reduces the harm of hydrogen fluoride to the environment and human body, protects the environment, and conforms to the concept of sustainable development.

[0083] Further, in step S4, the alkaline material solution is any one of sodium hydroxide or potassium hydroxide.

[0084] Furthermore, the copper removal agent a is iron powder, and in the process of replacing copper, forming metal copper powder and filtering, the amount of copper removal agent added is controlled to be 1.05 to 1.2 times the molar amount of copper ions in the solution; the excess iron is removed by oxidation precipitation with hydrogen peroxide, wherein the oxidant is hydrogen peroxide. The beneficial effect of this process is that cheap iron powder can be used instead of expensive metal nickel as a copper removal agent, which reduces costs, and metal copper powder can be recovered as a by-product, increasing revenue. Hydrogen peroxide, as an oxidant, can effectively oxidize iron ions into iron hydroxide precipitation, which is convenient for separation and filtration, and will not cause environmental pollution.

[0085] Further, the added oxidant is hydrogen peroxide, and the copper remover b is any one of nickel sulfide or sodium sulfide. The beneficial effect of this process is that nickel sulfide or sodium sulfide can be used as a copper remover to generate copper sulfide precipitation, which is convenient for separation and filtration, and copper sulfide can also be recovered as a byproduct, increasing revenue. Hydrogen peroxide, as an oxidant, can also effectively oxidize iron ions to ferric hydroxide precipitation, which is convenient for separation and filtration, and also does not cause environmental pollution.

[0086] Furthermore, the insoluble anode for electrolysis is a corrosion-resistant titanium-coated lead dioxide anode, and the anode is a metal titanium plate. The electrode reaction equation is as follows:

[0087] The main reaction equation of nickel electrolysis is:

[0088] Anode: H2O-2e=2H + +1 / 2O2↑

[0089] Cathode: Main reaction Ni 2+ (Co 2+ )+2e=Ni(Co)

[0090] Side reaction: 2H + +2e=H2↑

[0091] The total electrode reaction of nickel sulfate solution electroplating process:

[0092] NiSO4+H2O=Ni+H2SO4+1 / 2O2↑

[0093] Further, in step S6, the pure nickel pre-electrolysis solution is electrolyzed by an insoluble anode to produce electrolytic nickel containing more than Ni99.96%, and the current density of the electrolysis is controlled at 0.1-0.5A / dm 2 , the voltage of electrolysis is controlled at 2.0-4.0V. The structure of the electrolytic cell of this embodiment includes an anode, a cathode, a diaphragm, an electrolyte, a power supply and an electrolyte circulation system. The anode is a corrosion-resistant titanium-coated lead dioxide anode, and the anode adopts a metal titanium plate. The cathode is a stainless steel plate. The diaphragm is a breathable diaphragm made of polypropylene fiber, which is used to prevent direct contact between the anode and the cathode while allowing the electrolyte to pass through. The electrolyte is a pure nickel electrolysis pre-liquid, and its main component is nickel sulfate. The power supply is a direct current power supply, which is used to provide the current and voltage required for electrolysis. The electrolyte circulation system includes a pump, a pipeline and a valve, which are used to extract the electrolyte from the bottom of the electrolytic cell, filter and cool it, and then reflux it from the top of the electrolytic cell to keep the electrolyte clean and at a temperature. The beneficial effect of this process is that the method of insoluble anode electrolysis can be used to efficiently produce high-purity electrolytic nickel, while avoiding the generation of anode mud, reducing waste treatment, and improving resource utilization.

[0094] In summary, the present invention provides a clean production process for comprehensive recovery of multiple metals and multiple elements in nickel-containing waste slag generated in the nitrogen trifluoride production process, which can effectively produce nickel into high-purity electrolytic nickel for reuse in the production system, and at the same time, the combined waste of fluorine and ammonia in the slag is converted into raw materials that can be reused in the production process, truly realizing a circular economy and a green and clean production process. The present invention has the following beneficial effects:

[0095] (1) The present invention utilizes an electric heating furnace to heat nickel-containing waste slag to sublime or decompose ammonium bifluoride therein, and resynthesizes ammonium bifluoride through a condensation system, or increases the concentration through tail gas water absorption to obtain hydrofluoric acid, thereby realizing the recycling of fluorine, reducing fluorine emission and pollution, and also saving raw material costs;

[0096] (2) The present invention utilizes an alkaline material solution to convert nickel fluoride, iron fluoride and copper fluoride in nickel-containing waste slag into nickel hydroxide, iron hydroxide and copper hydroxide, and simultaneously generates a sodium fluoride or potassium fluoride solution, which is evaporated to obtain a sodium fluoride or potassium fluoride crystal product, thereby achieving further recovery and utilization of fluorine and also increasing the income of by-products;

[0097] (3) The present invention utilizes the acidic anolyte of the electrolytic nickel system to dissolve nickel hydroxide, iron hydroxide and copper hydroxide in the electrolyte, removes metal impurities, obtains a pure nickel pre-electrolysis solution, and produces high-purity electrolytic nickel through insoluble anode electrolysis, thereby achieving efficient recovery and utilization of nickel and improving product quality;

[0098] (4) The present invention adopts a variety of copper removal agents and oxidants, and the most suitable method can be selected according to the actual situation, thereby realizing the recovery and utilization of copper and avoiding the influence of copper on nickel electrolysis;

[0099] (5) During the entire process of the present invention, no harmful waste is generated, achieving zero waste discharge, meeting the requirements of clean production, and having good environmental and social benefits.

[0100] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A clean production process for recycling nickel-containing waste, characterized in that: The clean production process includes the following steps: S1: placing the nickel-containing waste slag from nitrogen trifluoride electrolysis in an electric heating furnace for heating; S2: Sublime or decompose the ammonium bifluoride in the nickel-containing waste slag, condense, liquefy and crystallize through a condensation system to re-synthesize the ammonium bifluoride for sale or reuse; S3: The unsynthesized hydrogen fluoride in S2 is absorbed by tail gas water to increase its concentration, and commercial hydrofluoric acid is obtained for sale or reuse; S4: The main components of material a after volatilization treatment by heating in an electric furnace are nickel fluoride, iron fluoride and copper fluoride; material a is added to an alkaline material solution for conversion and leaching, and nickel fluoride, iron fluoride and copper fluoride are converted into nickel hydroxide, iron hydroxide and copper hydroxide, and sodium hydroxide or potassium hydroxide solution is converted into sodium fluoride or potassium fluoride solution; then evaporation is performed to obtain sodium fluoride or potassium fluoride crystal products for sale; S5: adding the acidic anolyte of the electrolytic nickel system to the nickel hydroxide, iron hydroxide and copper hydroxide slag obtained in S4, dissolving the nickel hydroxide, iron hydroxide and copper hydroxide in the electrolyte by using the acid in the anolyte, adding acid to the insufficient acid, and then removing metal impurities. After completion, filtering the reaction slurry to obtain a pure nickel pre-electrolysis solution; S6: The obtained pure nickel electrolytic pre-liquid is electrolyzed by insoluble anode to produce electrolytic nickel containing more than Ni99.96%.

2. A clean production process for recycling nickel-containing waste according to claim 1, characterized in that: The metal impurity removal process in step S5 is as follows: after filtering the solution, adding a copper removal agent a to replace copper, forming metal copper powder and filtering; then adding an oxidant to the filtrate to control the pH of the solution at 3-4, removing the iron in the solution into iron hydroxide; filtering the reaction slurry to obtain a pure nickel pre-electrolysis solution; the chemical equation of the reaction process is as follows: Ni(OH)2+H2SO4=NiSO4+2H2O Cu(OH)2+H2SO4=CuSO4+2H2O Fe(OH)2+H2SO4=FeSO4+2H2O CuSO4+Fe=Cu+FeSO4 2Fe 2+ +H2O2+4OH - =2Fe(OH)3。 3. A clean production process for recycling nickel-containing waste according to claim 1, characterized in that: The metal impurity removal process in step S5 is as follows: adding an oxidant to control the pH of the solution at 3-4, removing the iron in the solution as iron hydroxide; adding a copper removal agent b to precipitate copper after filtering the solution to form copper sulfide precipitation; filtering the reaction slurry to obtain a pure nickel pre-electrolysis solution; the chemical equation of the reaction process is as follows: Ni(OH)2+H2SO4=NiSO4+2H2O Cu(OH)2+H2SO4=CuSO4+2H2O Fe(OH)2+H2SO4=FeSO4+2H2O CuSO4+NiS=CuS+NiSO4 CuSO4+Na2S=CuS+Na2SO4 2Fe 2+ +H2O2+4OH - =2Fe(OH)3。 4. A clean production process for recycling nickel-containing waste according to claim 1, characterized in that: In step S1, the electric heating furnace is any one of an industrial frequency furnace, a medium frequency furnace, a resistance furnace, an induction furnace, an electric arc furnace, a plasma furnace, an electron beam furnace and an electric steam boiler.

5. A clean production process for recycling nickel-containing waste according to claim 1, characterized in that: In step S3, in the process of increasing the concentration by absorbing the tail gas water to obtain commercial hydrofluoric acid for sale or reuse, the temperature of the tail gas water is controlled at 10-50°C and the flow rate of the tail gas water is controlled at 0.5-1.0 m / s.

6. A clean production process for recycling nickel-containing waste according to claim 1, characterized in that: In step S4, the alkaline material solution is either sodium hydroxide or potassium hydroxide.

7. A clean production process for recycling nickel-containing waste according to claim 2, characterized in that: The copper removal agent a is iron powder. In the process of replacing copper to form metallic copper powder and filtering, the addition amount of the copper removal agent is controlled to be 1.05 to 1.2 times the molar amount of copper ions in the solution; the excess iron is removed by oxidation precipitation with hydrogen peroxide, wherein the oxidant is hydrogen peroxide.

8. A clean production process for recycling nickel-containing waste according to claim 3, characterized in that: The added oxidant is hydrogen peroxide, and the copper removal agent b is either nickel sulfide or sodium sulfide.

9. A clean production process for recycling nickel-containing waste according to claim 1, characterized in that: The insoluble anode for electrolysis is a corrosion-resistant titanium-coated lead dioxide anode or a titanium-coated iridium-ruthenium anode, and the cathode is a metal titanium plate; a nickel starter sheet is first produced, and then the nickel starter sheet is used as a cathode to produce Ni99.96% electrolytic nickel.

10. The clean production process for recycling nickel-containing waste according to claim 1, characterized in that: In step S6, the pure nickel pre-electrolysis solution is electrolyzed by an insoluble anode to produce electrolytic nickel containing more than 99.96% nickel, and the current density of the electrolysis is controlled at 0.1-0.5A / dm 2 , the electrolysis voltage is controlled at 2.0-4.0V.

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