590results about "Ferric oxides" patented technology

The invention relates to a waste lithium iron phosphate battery recycling method, in particular to a graded recycling method for lithium, iron, phosphorus and graphite in a waste lithium iron phosphate battery, and belongs to the technical field of lithium ion batteries and resource recycling of the lithium ion batteries. According to the method, the mode that oxidizing roasting and selective leaching are combined is adopted, the leaching rate and selectivity of lithium are effectively improved, the leaching rate of the lithium element is close to 100% under the optimized condition, and limit recovery of the lithium element is achieved; meanwhile, aiming at the problem that iron and phosphorus in the leaching residues are difficult to utilize, a wet ball milling and secondary acid leaching method is combined, phosphorus and iron elements are separated from negative electrode graphite firstly, and graded recovery of iron, phosphorus and graphite is achieved. According to the method, the high recovery rate of lithium is realized, and meanwhile, high-added-value products such as ferric oxide and sodium phosphate are prepared by efficiently recovering ferric phosphate.

The invention relates to the field of gas sensors, and discloses a hydrogen sulfide gas sensor and a method for detecting the concentration of hydrogen sulfide in gas. The hydrogen sulfide gas sensor comprises a substrate and a gas sensitive material, a cavity is formed in the substrate, the gas-sensitive material is located above the cavity, and the two ends of the gas-sensitive material are connected with the gold electrodes on the substrate; the gas sensitive material comprises graphene fiber and metal oxide loaded on the graphene fiber. The metal oxide is selected from one or more than two of oxides of Zn, Cd, Cu, Ni, Pd, Pt, Co, Ir, Fe, Mn, Cr, Mo, W, V, Ti, Mg and Al; the specific surface area of the gas sensitive material is 80-150m < 2 > / g; the loading capacity of the metal oxide is 0.05 to 5 weight percent. The hydrogen sulfide gas sensor can be self-heated, has high sensitivity to hydrogen sulfide gas, and is suitable for being applied to the field of gas monitoring.

The invention discloses a method for comprehensively recovering valuable elements from a waste lithium iron phosphate battery material. The method comprises the following steps: carrying out alkali leaching on black powder and / or pole piece materials of the waste lithium iron phosphate batteries, and then carrying out solid-liquid separation to obtain alkali leaching residues and an alkali leaching solution; carrying out acid leaching on the alkaline leaching residues, and then carrying out solid-liquid separation to obtain an iron oxide powder product and an acid leaching solution; the alkali leaching liquid is cooled and crystallized to obtain a sodium phosphate product and crystallization mother liquor, and the crystallization mother liquor can be circularly used for the alkali leaching process; adjusting the pH value of the acid leaching solution, precipitating and separating to obtain a lithium phosphate product and a lithium precipitation mother solution, wherein the lithium precipitation mother solution can be used for preparing a sodium sulfate product. The method can effectively separate iron, phosphorus and lithium products, and is high in recovery rate, simple, short in process, low in cost and suitable for industrial application.

The invention relates to the technical field of iron ore tailing resource utilization, in particular to a method for preparing iron oxide yellow by leaching iron ore tailings through an advanced oxidation technology, which comprises the following steps: adding a required amount of iron ore tailing powder into a persulfate solution, stirring to react, adding a reducing agent, boiling, filtering, adding alkali liquor to adjust the pH value, and filtering, thereby obtaining the iron oxide yellow. Pure liquid containing ferrous ions is obtained; taking part of the pure solution containing ferrous ions, and adding a potassium hydroxide solution to obtain an iron oxide yellow seed crystal solution; adding a pure solution containing ferrous ions into the iron oxide yellow seed crystal solution, adding an alkali solution to adjust the pH value, reacting, and separating and drying a product to obtain the iron oxide yellow. According to the method, the persulfate is adopted to leach iron from the iron ore tailings, and the iron oxide yellow is prepared from the leachate; harmless treatment of the iron ore tailings and value-added utilization of valuable resources are achieved, the raw material source of the iron oxide yellow industry is widened, and a wider prospect is provided for development of iron oxide yellow.

The invention discloses a Fe-Beta molecular sieve for N2O catalytic decomposition and a preparation method of the Fe-Beta molecular sieve. According to the method, chitosan and metal Fe < 3 + > ions are complexed to form a chitosan Fe < 3 + > complex, and then the complex, a silicon source, an aluminum source and a template agent are used as raw materials to prepare the Fe-Beta molecular sieve in one step through a hydrothermal method. Hydroxyl, amino and other groups rich in a chitosan molecular chain can effectively complex metal Fe < 3 + > ions to form a stable chitosan Fe < 3 + > complex, and the stable chitosan Fe < 3 + > complex is used as a Fe source to realize uniform dispersion of Fe species in the molecular sieve and effectively reduce formation of FexOy clusters and Fe2O3 nanoparticles, so that the N2O decomposition catalytic performance of the Fe-Beta molecular sieve is improved. Inorganic alkali metal ions are not introduced, so that a large amount of ammonia-nitrogen wastewater generated in a subsequent tedious ammonium exchange process can be avoided, the synthesis period is effectively shortened, and energy consumption, material consumption and environmental pollution are reduced.

The invention provides an amorphous nano oxide and a preparation method thereof, a negative electrode, a battery and an electric device, and relates to the technical field of lithium batteries. The preparation method comprises the following steps: carrying out coordination reaction on a raw material substance containing target metal ions and fumaric acid to obtain a metal organic framework material; and carrying out etching treatment on the metal organic framework material by utilizing ozone to obtain the amorphous nano oxide corresponding to the target metal ions. According to the preparation method provided by the invention, the metal organic framework material is etched by ozone, the oxide material is prepared and is used as the negative electrode material of the lithium ion battery, and the prepared oxide material is of an amorphous structure, has a nano-size and a porous structure, is beneficial to diffusion of lithium ions of the battery material, and effectively improves the cycle performance of the negative electrode material.

The invention provides a wet treatment process for laterite-nickel ore. The wet treatment process comprises the following steps: S1, carrying out acid leaching treatment on the laterite-nickel ore by adopting inorganic acid to obtain leached ore pulp; s2, the leached ore pulp is sequentially subjected to liquid-solid separation and countercurrent washing, and washed pulp and leached residues are obtained; s3, a first oxidizing agent and a first neutralizing agent are added into the washed slurry for iron and aluminum removal treatment, and a solution with iron and aluminum removed and iron and aluminum slag are obtained; s4, carrying out nickel and cobalt precipitation treatment on the solution subjected to iron and aluminum removal, so as to obtain precipitated slurry; s5, continuously carrying out dense separation treatment on the precipitated slurry to obtain underflow and overflow; and S6, the underflow is subjected to washing aftertreatment in sequence, and a cobalt nickel hydroxide product is obtained. The invention provides a short-process wet treatment process for laterite-nickel ore, the production cost and energy consumption are reduced, and meanwhile, the recovery rate of nickel and cobalt, the overall recovery rate of scandium and the quality of nickel-cobalt oxide products are improved.

The invention relates to the technical field of preparation of a lithium ion battery negative electrode material, in particular to a metal organic framework coating for improving the performance of an iron oxide negative electrode lithium ion battery and a preparation method of the metal organic framework coating. The metal organic framework coating mainly comprises the step of coating the iron oxide by growing a metal organic framework on the surface of the iron oxide in situ. According to the invention, in-situ synthesis of a metal organic framework material on the surface of iron oxide is innovatively proposed, and the iron oxide material is coated in a hollow structure through a structure provided by an organic framework, so that volume expansion and shrinkage of iron oxide in charge and discharge processes are effectively buffered. By regulating and controlling the mass ratio of the organic framework to the ferric oxide, the high-rate discharge performance and the specific discharge capacity of the ferric oxide negative electrode are improved.

A raw material solution containing trivalent iron ions, or trivalent iron ions and ions of a metal element that partially substitutes Fe sites, and an alkaline aqueous solution for neutralizing the raw material solution are added to a reaction system to adjust the pH of the reaction system from 1.0 to 3.0 or lower. Hydroxycarboxylic acid is added to the obtained reaction solution and the pH of the reaction system is then neutralized from 7.0 to 10.0 or lower. The obtained precipitate of a substituent metal element-containing iron oxyhydroxide is coated with silicon oxide, followed by heating so as to form particles of ε-iron oxide in which Fe sites are partially substituted by other metal elements, and then, a slurry containing the particles is classified. The iron-based oxide magnetic powder has a particle shape close to a perfect sphere and is suitable for use in a magnetic recording medium.

The invention aims to provide a device and method for extracting iron from red mud and preparing iron oxide red, and belongs to the technical field of resource utilization, hydrochloric acid is adopted to leach iron element in the red mud, and a ferric chloride solution is separated from leachate through an extraction process. And then, carrying out alkali precipitation, washing and firing to prepare the high-purity iron oxide red. By using the method disclosed by the invention, the iron resource in the red mud can be recycled, so that the dual purposes of resource utilization and environment-friendly treatment are achieved.

The invention provides a graphene-based hydrogen sulfide gas sensor and a preparation method thereof, and relates to the technical field of gas sensors. The preparation method of the graphene-based hydrogen sulfide gas sensor comprises the following steps: soaking the wood substrate in a mixed metal salt solution containing a water-soluble silver salt and a water-soluble transition metal salt; irradiating the soaked wood substrate by using a laser beam at room temperature under the condition of no shielding gas, so that lignin and cellulose in the wood substrate are cracked and reconstructed to form graphene; meanwhile, the mixed metal salt immersed in the wood substrate is decomposed to form bimetallic oxide nanoparticles including silver oxide nanoparticles and transition metal oxide nanoparticles, and the bimetallic oxide nanoparticles are dispersed on the surface of each layer of graphene to obtain a sensitive layer; and coating conductive materials on the wooden substrate and on the two sides of the sensitive layer to form a connecting electrode in contact with the sensitive layer, thereby obtaining the graphene-based hydrogen sulfide gas sensor.

4, 4 '-bipyridine (Bpy), 2, 5-thiophenedicarboxylic acid (Tdc), FeCl3. 6H2O, NiCl2. 6H2O, urea and tetrabutylammonium bromide are used as raw materials, a simple hydrothermal-calcination method is adopted to prepare the Fe2O3-coated Ni-MOF composite nanomaterial catalyst, X-ray diffraction (XRD), a scanning electron microscope (SEM) and a N2 adsorption and desorption technology are adopted to characterize a prepared sample, and the electro-catalytic oxygen evolution reaction (OER) activity of the Fe2O3-coated Ni-MOF composite nanomaterial catalyst is tested. Results show that compared with a single component, the activity of the composite nano-material catalyst is greatly improved, especially the composition-optimized Fe2O3-coated Ni-MOF-1 composite nano-material catalyst shows the highest catalytic activity, the composite nano-material catalyst catalyzes OER in 1M KOH, and the overpotential (eta 10) is only 330mV when the current density is 10mA / cm < 2 > and is close to the overpotential 291mV of a noble metal catalyst RuO2.

The invention provides a lithium supplement agent, and belongs to the technical field of energy storage, the lithium supplement agent comprises a lithium-rich lithium ferrite material and a coating layer coating the surface of the lithium-rich lithium ferrite material, and the material of the coating layer comprises lithium pyrophosphate. According to the invention, the technical problems of poor air stability, relatively poor safety and the like of the lithium-rich positive electrode material in the related technology can be solved, so that lithium can be effectively supplemented.

The invention provides a high-crystallinity modified iron oxide as well as a preparation method and application thereof, and relates to the technical field of organic solid waste treatment. The preparation method comprises the following steps: preparing a precursor MIL-88B by utilizing a hydrothermal method; the precursor MIL-88B is subjected to calcination treatment, and an iron oxide with the MIL-88B as the precursor is obtained; the temperature condition of the calcination treatment is 550-850 DEG C. The high-crystallinity modified iron oxide prepared by the preparation method improves methane production efficiency and stability, avoids competition of iron reducing bacteria, is stable in long-term operation and low in cost, and has both environmental and economic benefits.

The invention discloses a method for preparing high-quality artificial rutile through strengthened acid leaching of ilmenite concentrate, and belongs to the technical field of metallurgy. The method is used for solving the problems that a titanium-rich material obtained by an existing titanium-rich material preparation process is high in impurity content; and low-concentration acid leaching cannot achieve an efficient leaching effect. According to the method, a magnetic field is added in the acid leaching process. By means of the method, efficient leaching of titanium and iron elements under the low-concentration acid condition can be achieved, and the obtained artificial rutile is high in grade, high in efficiency and good in leaching effect.

The invention discloses a spodumene concentrate resourceful treatment method which comprises the following steps: carrying out wet treatment on spodumene acid clinker to prepare lithium-removed filter residues and leachate; carrying out neutralization treatment and desulfurization treatment on the leachate to obtain a lithium-containing purified solution, gypsum and iron oxide red, and carrying out lithium extraction treatment on the lithium-containing purified solution to obtain a lithium salt and mirabilite; the lithium-removed filter residues are treated through a process combining a beneficiation method and a chemical method, and water glass, nano kaolinite, ceramsite aggregate and tantalum-niobium concentrate are obtained. According to the method, whole-process slag-free production of the spodumene concentrate is achieved, and meanwhile the lithium-containing compound with the high purity and the high quality is obtained; and various valuable products can be obtained.

The invention provides a positive electrode material, a preparation method thereof and a lithium ion battery, and belongs to the technical field of battery materials. Comprising the following steps: carrying out acid treatment on ferric oxide to obtain acid-modified ferric oxide; and mixing the acid-modified iron oxide, a second iron source, a lithium source and a phosphorus source to obtain a mixture, and then roasting the mixture to obtain the positive electrode material. By performing acid treatment on the ferric oxide, on one hand, impurities and a loose oxide layer on the surface of the ferric oxide can be removed, more active sites can be exposed, the reactivity of the ferric oxide is matched with that of the second iron source, the reaction process is carried out synergistically, and formation of a regular and uniform-size crystal structure is promoted; a foundation is laid for obtaining a positive electrode material with excellent electrochemical performance; on the other hand, the surfaces of the iron oxide particles can be regulated and controlled, so that agglomeration among the particles can be reduced when the iron oxide particles are mixed with the second iron source particles, the dispersity of the particles is improved, and the mixture forms more excellent gradation.

The invention relates to the technical field of industrial waste resource utilization, and discloses a method for preparing an alpha-Fe2O3 byproduct polysilicate aluminum ferric material through industrial waste collaboration.The method comprises the steps that copper slag and red mud are evenly mixed and ground, and a mixture A is obtained; adding waste alkali liquor into the mixture A to obtain a solid-liquid mixture B; carrying out alkalization roasting on the solid-liquid mixture B, then carrying out ultrasonic reaction and carrying out solid-liquid separation to obtain a solid precipitate C and a filtrate D; adding hydrogen peroxide into the solid precipitate C, and calcining to obtain a solid E; grinding the solid E, blending into ore pulp, and carrying out magnetic separation on the ore pulp to obtain alpha-Fe2O3 and mineral active micro powder F; and reacting the filtrate D under an acidic condition, and curing to finally obtain the polysilicate aluminum ferric material. According to the method, the copper slag, the red mud and the waste alkali liquor in the iron-containing solid waste are used as raw materials to replace pure chemical reagents to prepare the high-added-value material, the problems that the existing solid waste / liquid utilization rate is low, the disposal cost is high and the like are solved, and value-added utilization of the iron-containing solid waste and the waste alkali liquor is achieved.

The invention discloses a method for preparing iron oxide red by using acidic ferrous wastewater, and belongs to the technical field of iron oxide pigments. The method comprises the following steps: by taking acidic ferrous wastewater generated by an iron oxide red factory as a raw material, adjusting the pH value, adding iron powder and phosphate to remove impurities, and carrying out solid-liquid separation to obtain a high-purity ferrous sulfate solution; and concentrating and crystallizing the obtained ferrous sulfate solution, dehydrating and drying, crushing and grinding, calcining at high temperature, and crushing to obtain the high-purity iron oxide red. According to the method, the high-purity iron oxide red pigment is obtained by firstly adjusting the pH value, then adding the iron powder and the phosphate to remove impurities, then separating out FeSO4. 7H2O by utilizing a crystallization technology, dehydrating, drying and then carrying out high-temperature calcination, the process is reasonable, the preparation method is simple and feasible, and the method is suitable for industrial production. Iron oxide red production wastewater can be comprehensively utilized, and the product quality is equivalent to or partially superior to that of precipitated iron oxide red.

The invention relates to the technical field of comprehensive utilization of titanium gypsum resources, in particular to a method for green and efficient resource utilization of titanium gypsum. The method comprises the following steps: pretreating titanium gypsum, modifying with sodium carbonate to obtain modified slag and a Na2SO4 solution, carrying out acid leaching treatment on the modified slag with hydrochloric acid, carrying out pH adjustment, chemical precipitation, aging and solid-liquid separation on the acid leaching solution to obtain an iron-enriched precipitate and a calcium-containing filtrate, and roasting the iron-enriched precipitate to obtain high-grade Fe2O3. And performing liquid-liquid reaction on the Na2SO4 solution and the calcium-containing filtrate to synthesize CaSO4 and NaCl. According to the method, iron in the titanium gypsum can be effectively removed and recycled, so that the conversion rate of calcium sulfate in the titanium gypsum reaches 96.21%, iron and calcium enter a liquid phase after the modified slag is subjected to acidolysis, the iron removal rate reaches 97.57%, the Ca leaching rate reaches 99.70%, an iron enrichment with the Fe2O3 grade being 82.50% is obtained after the acid leaching solution is subjected to chemical precipitation and roasting, and CaSO4 and NaCl are synthesized by the Na2SO4 solution and the calcium-containing filtrate. The method not only realizes high iron removal rate, but also realizes comprehensive utilization of calcium and iron, is low in input cost and simple in process, not only solves the problem of stockpiling of titanium gypsum, but also realizes recycling of resources, and has relatively high popularization value.

The invention relates to a striker type micro-nano robot for cell membrane breakthrough and a preparation process of the striker type micro-nano robot, in particular to a striker type micro-nano robot driving control method based on a photomagnetic coupling field and a rotary blasting type cell membrane breakthrough method. The invention discloses a striker type micro-nano robot for cell membrane breakthrough. The striker type micro-nano robot consists of a magnetic iron oxide core and a silicon dioxide needle handle, wherein the surface of one side of the magnetic iron oxide core is coated with a gold layer. The invention discloses a preparation process of a firing pin type micro-nano robot. The preparation process of the firing pin type micro-nano robot comprises the steps of sol-gel core preparation, magnetron sputtering and chemical precipitation needle handle preparation. Under the cooperative driving of an external magnetic field and a near-infrared light field, rotary blasting type breakthrough can be performed on a mononuclear membrane through the tip end of the needle handle.

Separating the specific gravity gt of the solid-liquid mixture type underflow red mud discharged in aluminum oxide production from liquid; continuously grading and separating out ferric oxide, trace heavy metal minerals and rare earth from the 5 g / cm < 3 > material, and carrying out solid-liquid separation treatment; the separated materials with the specific gravity smaller than or equal to 5 g / cm < 3 > are atomized and dispersed into particles and liquid drops, the particles and the liquid drops are quickly freeze-dried to prepare fine particles, and the fine particles are divided into sodium aluminosilicate and silicon oxide mixed particles, calcium compound mixed particles and crystallized sodium hydroxide, sodium aluminate and ice crystal particles through multi-stage specific gravity classification in the environment with the temperature smaller than-5 DEG C; and sublimating and dehydrating the separated sodium aluminosilicate and silicon oxide mixed particles and calcium compound mixed particles to form powder materials, and melting sodium hydroxide, sodium aluminate and ice crystal particles at normal temperature to form a solution containing sodium aluminate and sodium hydroxide.

A method and equipment for recycling alumina red mud. First, the alumina red mud is added to a mixed acid of hydrochloric acid and sulfuric acid for reaction to dissolve metals such as iron, aluminum, calcium, sodium, and a small amount of zinc, copper, magnesium, etc., and the solid silicon dioxide is left to be separated as building materials or glass raw materials; after the solution is collected, ammonium bicarbonate is added to obtain aluminum, calcium, and some metal precipitates and separated. Iron and sodium remain in the solution and continue to react with sodium hydroxide to obtain iron hydroxide precipitate and separate out sodium salts. After evaporation of the concentrated solution, iron oxide is obtained as a raw material for steel production; the aluminum, calcium, and other metal precipitates are added to sulfuric acid with a concentration of 90-98% for reaction. After all are dissolved, the solution is subjected to membrane separation and then carbonates are added to obtain calcium carbonate precipitate as a raw material for cement production; after evaporation of the concentrated solution, high-purity alumina is obtained and sent to an aluminum processing plant to produce pure aluminum or aluminum alloy products; the separated sodium salt solution is evaporated to be used as industrial and agricultural salt; the acid mist and harmful gases in the reactor process are treated by an absorption tower and then discharged. The present invention can make full use of the iron oxide, alumina, and effective components of alumina red mud, solves the problem of environmental pollution caused by the large amount of piled-up alumina red mud at present, has a low cost, and is suitable for the current alumina production plants.

The invention belongs to the technical field of lithium batteries, and particularly relates to a preparation method of a positive electrode material, the positive electrode material, a positive electrode plate, a battery and an electric device. The method comprises the following steps: mixing nitrate and a precursor in a solvent, and roasting to obtain the positive electrode material, wherein the precursor comprises LiFe (1-y) MyPO4, M comprises one or more metal elements in IVB family, VB family, VIII family, IIA family, IIIA family, IVA family and VA family, and y is 0-0.1. According to the method, the electronic conductivity of the positive electrode material is improved, and the specific capacity and cycling stability of the battery are improved.

The invention provides an oxidation intermediate and application thereof. The oxidation intermediate is obtained by oxidizing and calcining a waste lithium iron phosphate positive electrode material; primary particles (D90-D10) / D50 in the oxidation intermediate are less than or equal to 3. According to the method, the oxidation intermediate with specific particle size distribution is obtained by oxidizing and calcining the waste lithium iron phosphate positive electrode material, the sizes of particles in the oxidation intermediate are relatively consistent, and relatively high compaction density can be realized when the oxidation intermediate and other small-particle materials form size grading. On the basis that the oxidation intermediate and an iron source with small granularity are ground, large and small particles are compounded, the compaction density and the battery energy density of the recycled lithium iron phosphate positive electrode material are greatly improved, and double excellent effects are achieved.

The invention discloses a method for recovering fine iron powder, and relates to the technical field of resource recovery. The invention provides a process route of hydrochloric acid leaching, iron powder reduction, sulfuration impurity removal, evaporative crystallization, size washing and roasting, and impurities such as Cu and Co can be removed through iron powder reduction; then the characteristic that Ksp of NiS and CoS is smaller than that of FeS is utilized, FeS is used for sulfuration impurity removal, and precipitation and recovery of Ni and Co can be completed under the condition that Fe is not lost; finally, through evaporative crystallization, residual trace impurity elements in the impurity removal liquid can be enriched in the solution and are prevented from entering ferrous chloride crystals; and ferrous chloride can be efficiently converted into iron oxide red (or iron oxide yellow) through a roasting process, so that the equipment investment is reduced. According to the method, through optimization of the whole process, the fine iron powder generated by high-grade matte nickel hydrometallurgy can be converted into high-purity iron oxide red (or iron oxide yellow) in a recycling mode, and impurities such as Ni, Cu and Co in the fine iron powder can be effectively recycled.

The invention provides a high-added-value recycling method of silicon and iron elements in iron tailings, and relates to the technical field of high-value and resource utilization of metallurgical solid wastes. The method comprises the steps of iron tailing grinding, middle-stage magnetic separation, microwave roasting, water quenching, grinding, high-stage magnetic separation, first-stage hot-pressing acid leaching, vacuum roasting, water quenching, second-stage hot-pressing acid leaching, low-stage magnetic separation of weakly magnetic minerals, ultrasonic acid leaching for iron extraction, aging reaction, filtering, drying and roasting. And finally obtaining high-purity quartz powder of more than 4N grade and nano iron oxide of which the purity of Fe2O3 is more than 95%. According to the method, silicon and iron elements in the iron tailings are recycled in a layered and stepped manner, and the acid leaching filtrate generated in the preparation process of the high-purity quartz powder is subjected to closed treatment, so that valuable components of silicon and iron in the iron tailings are utilized at a high value to the maximum extent, and no secondary waste liquid is discharged; meanwhile, the problem of fluorine pollution in the traditional process is avoided in the process of preparing the high-purity quartz powder, and the method is low-carbon and green and has remarkable economic benefits.

The invention discloses lithium sulfide and a preparation method thereof. The preparation method comprises the following steps: (1) carrying out ball-milling mixing on iron powder, sodium sulfide and lithium sulfate in a first inert atmosphere to obtain a mixture; (2) calcining the mixture in a second inert atmosphere for the first time to obtain a reaction material; (3) stirring and washing the reaction material with an alcohol solvent in a third inert atmosphere, filtering to obtain filtrate and a filter cake, performing reduced pressure distillation on the filtrate to obtain a lithium sulfide crude product, washing the filter cake with deionized water, and filtering to obtain a solid by-product; and (4) carrying out secondary calcination on the lithium sulfide crude product in a fourth inert atmosphere to obtain lithium sulfide. The preparation method provided by the invention has the advantages of few synthesis steps, simple product purification and environmental protection.

The invention belongs to the technical field of iron oxide preparation, and discloses a method for purifying iron oxide for soft magnetic ferrite from red mud and application of the method. The red mud is subjected to crushing and wet grinding, and red mud slurry is obtained; the red mud slurry is subjected to magnetic separation, drying and grinding into powder, and a magnetic product containing ferric oxide is obtained; the magnetic product is subjected to acid leaching and suction filtration with hydrochloric acid, and first filtrate is obtained; carrying out alkaline leaching treatment on the first filtrate by adopting sodium hydroxide, filtering and drying to obtain a red brown dry material; grinding the red brown dry material into powder, washing with deionized water, carrying out suction filtration, and drying to obtain a first dry material; and grinding the first dry material to a powder state, and carrying out aerobic sintering to obtain the reddish brown solid iron oxide. The iron oxide extracted through the method can replace existing high-purity commercial iron oxide and can be applied to preparation and development of soft magnetic materials, and various properties of the soft magnetic materials are indifferent or even higher.