42 results about "Chromium(III) hydroxide" patented technology

The invention provides a method for preparing an iron-chromium electrolyte and electronic-grade ferrous chloride by using a stainless steel waste liquid. The method comprises the following steps: firstly, adding elemental iron and / or elemental chromium into the stainless steel waste liquid to obtain a chromium-containing ferrous chloride solution; then, sulfide is added, and nickel is removed; adding iron powder to increase the pH value to obtain chromium hydroxide precipitate and a ferrous chloride solution; dissolving chromic hydroxide in hydrochloric acid to obtain a chromic chloride solution; purifying the ferrous chloride solution to obtain an electronic-grade ferrous chloride crystal; and finally, adding a chromium chloride solution, the electronic-grade ferrous chloride crystal and hydrochloric acid according to a certain proportion, and stirring and mixing to obtain the iron-chromium electrolyte. The ferrous chloride prepared by the steps is relatively high in purity and less in waste; meanwhile, the prepared electrolyte is good in electrical property, low in attenuation rate and low in cost, the purpose of comprehensive recycling of resources is achieved, and the general trend of technical improvement is met.

The invention discloses a method for co-producing benzoic acid and chromic hydroxide from methylbenzene and chromium-containing waste liquid. The method comprises the following steps: sequentially adding methylbenzene, a catalyst aqueous solution and an organic solvent into a reaction kettle; adding chromium-containing waste liquid to adjust the pH value of a reaction system in the reaction kettle; setting reaction temperature and reaction pressure, keeping the temperature for a certain time, and reacting; adding alkali liquor into the reaction liquid, adjusting the pH to be alkaline, filtering to obtain chromium hydroxide precipitate, and calcining chromium hydroxide to produce chromium oxide green; and adding an extracting agent into the filtrate, extracting and separating to obtain an organic phase, removing the organic solvent by using a rotary evaporator, and carrying out silica gel column chromatography to obtain benzoic acid. The characteristic that the chromium-containing waste liquid is acidic is utilized, the chromium-containing waste liquid is recycled, and the preparation method can improve the yield of chromium oxide green, reduce the usage amount of sulfuric acid and reduce the discharge of the chromium-containing waste liquid, and has important economic and environment-friendly significance.

The invention relates to the field of chromium-containing waste liquid recovery, in particular to a method and system for recovering chromium in leaching waste liquid, and the method comprises the following steps: S1, adding alkali into the chromium-containing leaching waste liquid to adjust the pH value to 8 or above, and then adding ozone for oxidation to oxidize trivalent chromium into hexavalent chromium to obtain alkali-adjusted oxidized waste liquid; s2, adding a flocculation precipitator into the alkali-adjusting oxidation waste liquid, and removing impurities in a precipitation form to obtain a flocculation precipitation waste liquid; s3, acid is added into the flocculent precipitation waste liquid to adjust the pH value to 6.5 or below, then a reducing agent is added, hexavalent chromium is reduced into trivalent chromium, and acid-adjusted reduction waste liquid is obtained; s4, alkali is added into the acid-adjusted reduction waste liquid, the pH is adjusted to 8.5-9.5, trivalent chromium is precipitated in the form of chromic hydroxide, and chromic hydroxide precipitate and supernate are obtained. The method can enrich and recover the chromium element in the leaching waste liquid, has a high recovery rate, and has the advantages of high treatment efficiency, strong treatment capability, simple operation, stable recovery and the like.

The utility model discloses an industrial chromium-containing wastewater treatment device which comprises a reduction reaction tank, the right end of the reduction reaction tank is connected with the neutralization reaction tank, the right end of the neutralization reaction tank is connected with the coagulation reaction tank, and the right end of the coagulation reaction tank is connected with the inclined tube sedimentation tank. The method comprises the following steps: adding sodium hydroxide into trivalent chromium ions to generate indissolvable chromic hydroxide, firstly adding a polyacrylamide flocculant to generate relatively large muddy alum, then adding polyaluminum chloride to settle, settling in an inclined tube settling zone in an inclined tube settling tank, enabling settled sewage to enter a clean water tank, and when the chromium content detected by an online heavy metal monitor is lower than 0.5 mg / L, discharging the sewage from the clean water tank. The industrial wastewater meeting the standard is discharged, and the device is compact in structure, small in occupied area, convenient to operate, high in treatment efficiency, low in treatment cost and easy to popularize.

The invention relates to the field of vanadium and chromium separation, and particularly discloses a method for removing impurities phosphorus, chromium and silicon in a sodium modified vanadium solution, which comprises the following steps: S100, adjusting the pH value of the sodium modified vanadium solution to enable the pH value of a solution system to be 8.0-9.0 at room temperature to obtain a pretreated sodium modified vanadium solution; s200, heating the pretreated sodium vanadium solution, sequentially adding a reducing agent and a polyelectrolyte into the solution while stirring, and carrying out phosphorus and chromium removal reaction while stirring; s300, after the removal reaction of phosphorus and chromium is carried out for a period of time, adding a silicon removal agent, and carrying out a removal reaction of silicon; and S400, after the silicon removal reaction is finished, standing sedimentation and solid-liquid separation are carried out, impurity-removed slag is washed with water and then merged into the filtrate, and purified vanadium liquid is obtained. According to the method, firstly, glucose is adopted to selectively reduce hexavalent chromium into trivalent chromium under the weakly alkaline condition, pentavalent vanadium is not reduced, the trivalent chromium forms chromium phosphate and chromium hydroxide precipitates in a weakly alkaline solution, and meanwhile, the chromium removal efficiency is improved in a polyelectrolyte coagulation mode.

The application discloses a preparation method of vanadium-doped and high-hydrated mangan-chromian spinel monocrystal under high temperature and high pressure. The cylindrical mangan-chromian spinel sample is prepared by taking solid rose triangular rhombic manganese carbonate crystal, solid chromium (III) acetate hydroxide crystalline powder, solid vanadium (IV) acetylacetonate oxide powder, solid oxalic acid powder, solid bixbyite powder, solid chromium hydroxide powder and liquid dilute nitric acid as starting raw materials; two pieces of water source sheets are made from the bixbyite powder and the chromium hydroxide powder with a weight ratio of 4:1; the two pieces of water source sheets are placed at two ends of the cylindrical mangan-chromian spinel sample and then are placed into a double-capsule structure experimental sample bin with an inner layer sleeve being a graphite tube and an outer layer sleeve being a gold-palladium alloy tube; the high temperature and high pressure reaction is carried out to obtain the mangan-chromian spinel monocrystal; and the preparation technology blank of the vanadium-doped and high-hydrated mangan-chromian spinel large-particle monocrystal under the current high temperature and high pressure conditions is solved.

The application discloses a preparation method of a nickel-doped and high-hydrated cobalt-chromium-iron ore monocrystal under high temperature and high pressure, and the method comprises the following steps: preparing a cylindrical cobalt-chromium-iron ore sample by taking solid basic cobalt carbonate powder, solid chromium (III) acetate hydroxide crystal powder, solid nickel stearate, solid oxalic acid powder, solid chromium hydroxide powder, solid nickel hydroxide powder and liquid dilute nitric acid as starting raw materials; preparing water source sheets by taking chromium hydroxide powder and nickel hydroxide powder in a weight ratio of 4:1; placing two water source sheets at two ends of the cylindrical cobalt-chromium-iron ore sample respectively and then putting them into a double-capsule structure sample bin; and obtaining a cobalt-chromium-iron ore monocrystal after high-temperature and high-pressure reaction, so that the blank of the preparation technology of the nickel-doped and high-hydrated cobalt-chromium-iron ore large-grain monocrystal under the current high-temperature and high-pressure condition is solved, and the experimental sample of the nickel-doped and high-hydrated cobalt-chromium-iron ore large-grain monocrystal is obtained.

The invention discloses a chromium-containing wastewater treatment and recovery treatment line and a recovery treatment method thereof. The ion exchange system is used for carrying out ion exchange adsorption on the hexavalent wastewater; the alkali washing system is used for outputting alkali liquor to the ion exchange system; the washing system is used for outputting washing water to the ion exchange system; the pickling system is used for outputting acid liquor to the ion exchange system; the chromium recovery treatment branch line is used for receiving the hexavalent wastewater of the ion exchange system, mixing the hexavalent wastewater with sulfur powder and alkali liquor to prepare chromium hydroxide, then carrying out filter pressing on the chromium hydroxide, outputting a chromium hydroxide filter cake to the recovery calcination treatment line, and outputting a press filtrate to the press filtrate recovery branch line; the press filtrate recovery branch line is used for recovering sodium thiosulfate from the press filtrate; and the recycling and calcining treatment line is used for calcining the chromium hydroxide filter cake into Cr2O3. According to the scheme, the purposes of micro discharge and even zero discharge of the chromium-containing wastewater are achieved, and the problem that a large amount of chromium-containing hazardous waste sludge is generated by depending on a chemical reduction-precipitation method in traditional chromium-containing wastewater treatment is solved.

The application discloses a preparation method of titanium-doped and high-hydrated magnesio-chromian spinel monocrystal under high temperature and high pressure, and the method comprises the following steps: preparing a cylindrical magnesio-chromian spinel sample by taking solid basic magnesium carbonate powder, solid basic chromium acetate crystal powder, liquid tetraisopropyl titanate, solid oxalic acid powder, solid brucite powder, solid chromium hydroxide powder and liquid dilute nitric acid as starting raw materials; preparing water source sheets by taking brucite powder and chromium hydroxide powder with a weight ratio of 4:1 as water sources; placing two water source sheets at two ends of the cylindrical magnesio-chromian spinel sample and putting them into a double-capsule structure sample bin together to carry out high temperature and high pressure reaction, so as to obtain titanium-doped and high-hydrated magnesio-chromian spinel monocrystal; and the method solves the blank of the preparation technology of the titanium-doped and high-hydrated magnesio-chromian spinel large-grain monocrystal under the current high temperature and high pressure conditions, and obtains experimental samples of the titanium-doped and high-hydrated magnesio-chromian spinel large-grain monocrystal.

The invention discloses a low-chromium-content propane dehydrogenation catalyst and application thereof. The catalyst comprises a composite carrier of aluminum oxide and an MCM-41 molecular sieve, an active component Cr and one or more of auxiliaries Yb, Ga, Sn, Zn and Ba. The preparation method comprises the following steps: preparing the composite carrier by adopting a wet mixing method; the preparation method comprises the following steps: carrying out high-temperature pressurized crystallization precipitation on a precursor of Cr and an auxiliary agent under an alkaline condition to prepare modified chromium hydroxide hydrogel; the hydrogel is washed, dried and crushed, then the hydrogel and the composite carrier are subjected to ultrasonic impregnation in acid liquor, then microwave radiation drying is conducted, and finally the catalyst is obtained through forming, drying, roasting and reduction. The catalyst obviously reduces the chromium content (the Cr loading amount is 1-3% based on the carrier), reduces the environmental pollution and the production cost, has high mechanical strength, high-temperature stability and hydrothermal stability, is used for the propane dehydrogenation reaction, has the propane conversion rate of 48% and the propylene selectivity of more than 95%, has low carbon deposition amount, and is suitable for industrial production. Wide industrial application prospects are shown.

The present invention provides a method for resource recovery of chromium-containing electroplating sludge, including the process steps of pigment preparation and metal recovery. Among them, the ceramic pigment is prepared by a solid-phase method using chromium-containing electroplating sludge and calcium-silicon substances as raw materials. The waste liquid generated during the preparation process realizes the cascade recovery of metals through the methods of adding iron powder to reduce and precipitate copper, hydrogen peroxide to oxidize and precipitate iron, and reduction and flocculation to precipitate chromium. The recovered chromium hydroxide can be returned to the raw material electroplating sludge for secondary utilization. The present invention prepares a ceramic pigment with good color rendering effect and excellent acid and alkali resistance through a simple solid-phase reaction method. Moreover, the purity of the grossularite phase Ca3Cr2(SiO4)3 is relatively high, with stable properties, acid and alkali resistance, and at the same time realizes the cascade recovery of metals. The present invention realizes the resource utilization of chromium-containing sludge, a solid hazardous waste, in the field of ceramic pigments. The process is simple, easy to control, environmentally friendly, and the raw materials are cheap and easily available, greatly reducing the production cost and having good economic and environmental benefits.

A recovery treatment line and method for chromium-containing wastewater; the recovery treatment line comprises a recovery reactor, a reducing agent feeder, a lye feeder and a recovery filter pressing system; the output end of the recovery reactor is communicated with the recovery filter pressing system, and is used for outputting chromium hydroxide wastewater to the recovery filter pressing system; a primary filter press is used for receiving the chromium hydroxide wastewater of the recovery reactor, and performing filter pressing treatment on the chromium hydroxide wastewater, outputting filtrate to a liquid phase recovery device, and outputting chromium hydroxide to a filter crushing device; the filter crushing device is used for performing crushing treatment on the chromium hydroxide, and outputting the chromium hydroxide to a cleaning tank; the cleaning tank is used for cleaning the chromium hydroxide, and outputting the chromium hydroxide to a secondary filter press; the secondary filter press performs filter pressing treatment on the chromium hydroxide of the cleaning tank, and obtains chromium hydroxide. The scheme solves the problem of high treatment difficulty of chromium-containing wastewater.

The invention relates to the technical field of hydrometallurgy, in particular to a vanadium and chromium separation method for a vanadium and chromium solution. The method comprises the following steps: adjusting the pH value of the vanadium-chromium solution to 2-4; adding a reducing agent into the vanadium-chromium solution; adding tetraalkylammonium into the obtained solution, stirring, and filtering to obtain a vanadium-containing precipitate and a chromium-containing solution; washing, drying and calcining the vanadium-containing precipitate to obtain vanadium pentoxide; adding alkali into the chromium-containing solution, stirring, filtering to obtain chromium hydroxide precipitate, washing, drying and calcining the chromium hydroxide precipitate to obtain chromium sesquioxide. According to the method, Cr (VI) is selectively reduced into Cr (III) through a reducing agent, vanadium in the solution exists in the form of polyvanadate anions and chromium exists in the form of Cr < 3 + >, then tetraalkylammonium is selected for vanadium precipitation, the radius of tetraalkylammonium ions is larger than that of NH4 < + > in a traditional vanadium precipitation agent, the tetraalkylammonium ions can be combined with the polyvanadate anions more easily to repel Cr < 3 + >, and therefore the vanadium precipitation effect is improved. Therefore, the separation of vanadium and chromium is simply, conveniently and efficiently completed.

The invention relates to a method for recycling iron, chromium and nickel in a waste acid solution, which comprises the following steps: (1) taking the waste acid solution containing + 3-valent iron ions, + 3-valent chromium ions and + 2-valent nickel ions as a reduction end solution, taking a chromium-containing iron acid solution containing + 2-valent iron as an oxidation end solution, carrying out diaphragm electrolysis treatment to obtain a ferrous iron acid solution at the reduction end, oxidizing the end to obtain an iron-chromium solution containing ferric iron; (2) carrying out nickel removal treatment on the ferrous-iron-containing acid liquor through hydrogen sulfide to obtain a nickel sulfide product and nickel-removed liquor; the nickel-removed solution is sequentially subjected to iron-chromium separation and acid dissolution to obtain a chromium-containing iron acid solution containing + 2-valent iron, and the chromium-containing iron acid solution is circulated to the step (1) to be used as an oxidation end solution; and (3) the iron-chromium solution is sequentially subjected to iron removal and chromium precipitation, and a chromium hydroxide product is obtained. Divalent iron and trivalent chromium are separated by utilizing valence change of iron and property difference between divalent iron and trivalent iron; nickel is removed by hydrogen sulfide, so that iron, chromium and nickel in the waste acid solution are completely separated, and no byproduct waste is produced.

A lead wire for a nonaqueous electrolyte battery according to the present disclosure is provided with: a conductor; and an insulating film that has one or more layers and covers at least a portion of the outer peripheral surface of the conductor, the conductor having a conductor film that covers at least a portion of the surface, the conductor film containing a metal element and a trivalent chromium compound containing chromium hydroxide, and the outermost surface of the conductor film being provided with an insulating layer that covers at least a portion of the outer peripheral surface of the conductor. The ratio of the mass [mg / m2] per unit area of chromium contained in the chromium hydroxide to the mass [mg / m2] per unit area of chromium contained in the trivalent chromium compound is 0.30-0.90, and the insulating film has an innermost layer laminated on the surface of the conductor coating film. The innermost layer is mainly composed of a resin component containing maleic anhydride-modified polypropylene, and the acid modification rate of the resin component is 0.02 mass% or more and 0.50 mass% or less.

The application provides a method for co-extracting vanadium and chromium from high-chromium vanadium slag and application thereof. The method comprises the following steps: roasting high-chromium vanadium slag and calcium salt to obtain roasted clinker, leaching the roasted clinker with a leaching agent to obtain a leaching solution, cooling the leaching solution to obtain sodium orthovanadate and a crystallization mother liquor; adding calcium oxide to the crystallization mother liquor to obtain a chromium-containing solution, performing first reduction on the chromium-containing solution to obtain chromium hydroxide, and performing first calcination on the chromium hydroxide to obtain chromium trioxide; mixing the sodium orthovanadate, water and carbon dioxide to obtain sodium metavanadate, sequentially performing transformation and second reduction on the sodium metavanadate, and performing second calcination to obtain a reduction clinker; mixing the reduction clinker, washing water and sodium bicarbonate mother liquor to obtain a sodium-containing solution and primary vanadium trioxide, and washing the primary vanadium trioxide to obtain vanadium trioxide. The application realizes high-value conversion of high-chromium vanadium slag, and simultaneously considers simplicity and economy, and no high ammonia nitrogen, high salt water and ammonia-containing waste gas are generated.

The present application relates to the technical field of chromium oxide preparation, and particularly relates to a preparation method of chromium oxide. The present application provides a preparation method of chromium oxide, comprising the following steps: after high-temperature leaching of a crude chromium hydroxide leaching solution, solid-liquid separation is performed to obtain a first solid phase and a first liquid phase; the first liquid phase is subjected to extraction to obtain an extraction phase and a raffinate phase; the raffinate phase is mixed with sodium hydroxide to perform chromium precipitation to obtain chromium hydroxide and a first chromium precipitation mother liquor; the chromium hydroxide is subjected to calcination to obtain chromium oxide; an extraction reagent used in the extraction includes an extractant and a diluent; the extractant includes two or more of P507, P204, TOPO, MIBK and TBP; and the diluent includes one or more of sulfonated kerosene, No. 260 solvent oil and isooctanol. The prepared chromium oxide has a main content of >98%, and can reach the smelting metal chromium level.

The invention relates to the technical field of catalysts, in particular to a chromium fluoride catalyst for a hydrofluorocarbon HF removal reaction and a preparation method and application of the chromium fluoride catalyst. Comprising the following steps: (1) precipitating and aging a chromium salt to obtain a trivalent chromium precipitate, mixing the trivalent chromium precipitate with ammonium fluoride, carrying out ball milling, and drying to obtain a chromium fluoride precursor, the mass ratio of the trivalent chromium precipitate to the ammonium fluoride being 1: (0.7-1.4); and (2) carrying out roasting fluorination treatment on the chromium fluoride precursor, and carrying out hydrogen fluoride fluorination treatment to obtain the chromium fluoride catalyst. The trivalent chromium precipitate and ammonium fluoride are subjected to ball-milling mixing, so that ammonium fluoride and chromium hydroxide are subjected to a pre-fluorination reaction, heat release in subsequent roasting fluorination treatment is reduced, the roasting fluorination treatment process is milder, ammonia gas generated during roasting is used as a pore-forming agent, the specific surface area and pore volume of the catalyst are increased, and the specific surface area and pore volume of the catalyst are increased. The sintering of chromium fluoride in the high-temperature roasting process is inhibited, and meanwhile, the generation of high-valence chromium is prevented.

The invention relates to an aluminum profile production wastewater treatment device which comprises a rack, a treatment barrel is arranged on the rack, a plurality of acid adjusting reduction barrels are arranged on the inner wall of the treatment barrel in a surrounding mode, and a chromium-containing wastewater storage and transportation mechanism and an acid adjusting reduction storage and transportation mechanism are arranged on the treatment barrel and located above the acid adjusting reduction barrels respectively. A first liquid discharging mechanism is arranged on the acid adjusting reduction cylinder; the area of an unreacted area can be reduced when the precipitant is in contact with the trivalent chromium solution, sudden increase of the local PH value of the surface of the trivalent chromium solution can be prevented, convective mixing can be formed after the precipitant is in contact with the trivalent chromium solution, so that the precipitant is in uniform contact with the trivalent chromium solution, and the reaction rate is increased; the method can prevent a chromium hydroxide precipitate layer generated by reaction on the surface of the trivalent chromium solution from hindering diffusion and flow of a subsequent precipitant, and can enable the trivalent chromium solution and the precipitant to uniformly, fully and completely react to generate a chromium hydroxide precipitate.

The invention discloses a method for preparing chromium oxide green from beta-menadione chromium-containing waste liquid, which comprises the following steps: step 1, adding a chromium source into the beta-menadione chromium-containing waste liquid to adjust the acid value, and heating the solution to form feed liquid A; step 2, adding sodium hydroxide and a reducing agent into the sodium dichromate or sodium chromate solution to prepare feed liquid B for later use; step 3, slowly and continuously adding the feed liquid B into the fully stirred feed liquid A, carrying out heat preservation and curing to form feed liquid C, carrying out plate-frame pressure filtration, pulping and washing on the feed liquid C to obtain a chromium hydroxide filter cake, and calcining and crushing the chromium hydroxide filter cake to obtain a chromium oxide green product; and performing chromium removal, filter pressing, concentration evaporation and electrolysis on the washing solution to obtain sodium hydroxide and sulfuric acid. The chromium oxide green prepared by the invention has lower hexavalent chromium content than other chromium oxide green, and is more stable; the cost of the method is lower than that of chromic anhydride calcination; the washing solution can also be converted into an important raw material in the chemical industry.

The application discloses a preparation method of 4N high-purity chromium, and comprises the following steps: step one, adding metal chromium into concentrated sulfuric acid mixed with water for leaching; step two, adopting a Mohr salt method; step three, obtaining a chromium (III) solution through extraction; step four, performing alkaline precipitation on the chromium (III) solution, and obtaining chromium hydroxide through filtration; step five, performing roasting on the chromium hydroxide, and obtaining chromium trioxide; step six, mixing the chromium trioxide with aluminum particles and a heating agent, and sequentially performing vacuum aluminothermic reduction and vacuum suspension smelting to obtain 4N chromium. The preparation method shortens the preparation period under the premise of ensuring the iron removal effect by adopting the process of the Mohr salt method combined with extraction of iron, and effectively reduces the impurity content of gas, iron and the like by adopting the process of vacuum aluminothermic reduction combined with vacuum suspension smelting, so that 4N chromium is obtained, and the method is suitable for the technical field of high-purity metal chromium preparation.

The invention discloses a method for producing an iron-chromium flow battery electrolyte by using an iron-chromium alloy. The method comprises the following steps: preparing an iron-chromium alloy solution, adding reduced iron powder, precipitating chromium ions, removing impurities, filtering, dissolving Cr (OH) 3, and removing impurities from filtrate to obtain a ferrous chloride solution; and preparing the iron-chromium flow battery electrolyte. According to the method for producing the iron-chromium flow battery electrolyte by using the iron-chromium alloy, the iron-chromium alloy reacts with hydrochloric acid, a solution containing iron and chromium is prepared, chromium ions generate chromium hydroxide precipitation separation by adjusting the pH value of the solution, ferric ions generate ferrous ions by adding reduced iron powder, and the iron-chromium flow battery electrolyte is obtained. The preparation method comprises the following steps: adding a chromium hydroxide precipitate into a chromium hydroxide solution, then adding a pure ferrous chloride solution obtained after impurity removal, reacting the chromium hydroxide precipitate with hydrochloric acid to form a pure chromium trichloride solution, and compounding the pure chromium trichloride solution with hydrochloric acid to form the iron-chromium flow battery electrolyte, thereby having the effects of simple process and cost reduction.

The invention discloses a method for preparing chromium trioxide and vanadium pentoxide by using chromium-containing vanadium slag, comprising: calcifying and roasting the chromium-containing vanadium slag to extract vanadium by acid leaching to obtain a vanadium-containing solution, then sodiumizing and roasting the separated solid to extract chromium by water to obtain a chromium-containing solution, adding ammonium carbonate to adjust the pH value and temperature of the vanadium-containing solution to precipitate vanadium, filtering and separating to obtain ammonium metavanadate, and roasting the ammonium metavanadate to obtain vanadium pentoxide; adding a reducing agent to the chromium-containing leaching solution, adjusting the pH to precipitate chromium, filtering to obtain chromium hydroxide precipitate, and precipitating and roasting to obtain chromium trioxide. The vanadium-chromium waste liquid can be recycled. The invention selects different roasting temperatures at the front end to achieve efficient separation of vanadium and chromium, avoids the complex separation process of vanadium and chromium at the back end, shortens the vanadium-chromium separation process, and the purity of the vanadium pentoxide and chromium trioxide obtained respectively is relatively high. At the same time, the vanadium-chromium waste liquid can be returned for recycling, thereby avoiding water pollution and effectively saving production costs.

The invention discloses a preparation method of 4N high-purity chromium. The preparation method comprises the following steps that 1, concentrated sulfuric acid and water are mixed, and then metal chromium is added for leaching; step 2, a Moire salt method; 3, extracting to obtain a chromium (III) solution; 4, performing alkaline precipitation on the chromium (III) solution, and filtering to obtain chromium hydroxide; 5, roasting the chromium hydroxide to obtain chromium trioxide; and 6, the chromium trioxide is mixed with aluminum particles and a heat generating agent, vacuum aluminothermic reduction and vacuum suspension smelting are sequentially conducted, and the 4N chromium is obtained. According to the preparation method, the preparation period is shortened on the premise that the iron removal effect is guaranteed by adopting the one-time Moire salt method matched with the extraction iron removal process, then the content of gas, iron elements and other impurities is effectively reduced by adopting the vacuum aluminothermic reduction matched with the vacuum suspension smelting process, 4N chromium is obtained, and the preparation method is suitable for the technical field of high-purity metal chromium preparation.

The invention belongs to the technical field of inorganic chemical industry, and particularly relates to a method for continuously preparing chromium hydroxide, which comprises the following steps: (1) heating a solution containing Cr < 6 + >, adding a reducing agent and a reducing auxiliary agent, maintaining the pH value of the system at 10-12, and carrying out a reduction reaction to obtain chromium hydroxide slurry; (2) standing and settling the obtained slurry, separating out two parts of chromium hydroxide slurry according to the volume ratio of (1.5-3): 1, and recycling the chromium hydroxide in the step (1) to control the growth of crystal nucleus; and (3) adding sulfuric acid and dilute sulfuric acid into the separated chromium hydroxide slurry step by step, adjusting the pH value of the system to 8-9, filtering, and washing until the pH value of washing water is 6.5-7.5 to obtain a target product. Through optimization of reaction conditions, introduction of the chromium hydroxide slurry and continuous process design, the problems of fine chromium hydroxide particles, high water content, low process efficiency and the like in the prior art are solved, and the method is suitable for the fields of chromium salt production, electroplating wastewater treatment, metal recovery and the like.

The invention relates to a method for selectively and efficiently separating and recovering chromium from vanadium and chromium slag leaching liquid. According to the technical scheme, the method comprises the steps that vanadium and chromium slag sub-molten salt is subjected to alkaline leaching, and vanadium and chromium slag leaching liquid is obtained; and the vanadium and chromium slag leaching solution is put into an evaporation device to be evaporated and concentrated, and the vanadium and chromium slag alkaline leaching concentrated solution is obtained. Putting the vanadium and chromium slag alkaline leaching concentrated solution into a crystallizer, adding a potassium-containing additive into the vanadium and chromium slag alkaline leaching concentrated solution, and carrying out reaction, solid-liquid separation and washing under a first stirring condition to obtain potassium sodium chromate crystals and a post-crystallization solution; dissolving the potassium sodium chromate crystal to obtain a potassium sodium chromate solution, and adjusting the pH value with sulfuric acid; and adding sodium sulfite into the potassium sodium chromate solution, reacting under a second stirring condition, and carrying out solid-liquid separation to obtain a chromium hydroxide solid. And calcining the chromium hydroxide solid to obtain chromium sesquioxide. The method has the characteristics of simple process, low cost, strong adaptability and environmental friendliness, is suitable for the vanadium-chromium-containing solution with high strong alkalinity, and is good in vanadium-chromium separation effect and high in chromium recovery rate.

A method for co-removing chromium and silicon from a sodium-containing vanadium solution by selective reduction. The method comprises: adjusting the pH value of a sodium-containing vanadium solution such that the pH value of the system solution is 10.5-11.5 at 60°C to obtain a pretreated sodium-containing vanadium solution; adding a preset amount of reducing agent to the pretreated sodium-containing vanadium solution at a time for reduction reaction; adding a silicon removal agent to a reaction system at the last stage of the reduction reaction for reaction to obtain a first intermediate reaction solution, carrying out solid-liquid separation on the first intermediate reaction solution, washing a solid phase with water, and then combining the solid phase with a filtrate to obtain an impurity removal solution; and carrying out an oxidation purification treatment on the impurity removal solution to obtain a purified solution. In the present invention, under specific concentration and pH conditions of a sodium-containing solution, vanadium mainly exists in the form of a pyrovanadate, shows relatively low oxidizability and stable properties, and is not prone to reducing. Even if a small part of vanadium is reduced, vanadium still remains as a vanadite in the solution, while a chromate is selectively reduced into chromium hydroxide, thereby completing the separation of vanadium and chromium in the form of a chromium hydroxide precipitate.

The invention discloses a comprehensive utilization technology of sodium thiosulfate wastewater and chromium-containing wastewater resources, which comprises the following steps: uniformly mixing sodium thiosulfate wastewater and hexavalent chromium wastewater in proportion, adding sulfuric acid to adjust the pH value, heating to a certain temperature through steam, and keeping the temperature for reduction reaction; adding caustic soda flakes into the completely reacted materials to adjust the pH value, then stirring and precipitating, and carrying out heat preservation for curing reaction; and carrying out plate-frame pressure filtration on the completely cured material, and washing to obtain a chromium hydroxide product, wherein the hexavalent chromium in the filtered water reaches the specified index. The method has the beneficial effects that the comprehensive value cost of two kinds of wastewater is fully utilized, comprehensive utilization of resources is realized, and the treatment cost is greatly reduced; the generated chromium hydroxide is used for calcining to produce 99% metallurgical grade chromium oxide green products, so that chromium resources in the wastewater are completely recovered and productized; a dispersing agent is added in the precipitation process, microwave and ultrasonic dispersion treatment is carried out at the same time to prevent precipitation from gathering, a calcined product is ground, and the nanoscale chromium oxide green is obtained.

The invention discloses a method for preparing a chromic oxide and sodium sulfate solution from chromium-containing sodium hydrogen sulfate, which comprises the following steps: preparing chromium-containing sodium hydrogen sulfate into a sheet by a sheet preparation machine, and calcining to obtain a calcined product; adding the calcined product into water to prepare a feed liquid, then adding sodium hydroxide for neutralization to prepare a mixed solution of chromic hydroxide and sodium sulfate, carrying out heat preservation and curing, then carrying out filter pressing to obtain a filter cake, then washing and carrying out filter pressing on the filter cake to obtain a chromic hydroxide filter cake, and carrying out filter pressing to obtain a filtrate which is a sodium sulfate solution; and calcining the chromium hydroxide filter cake to obtain chromium sesquioxide. According to the resource utilization method for the by-product chromium-containing sodium hydrogen sulfate in the chromic anhydride production process, the chromium-containing sodium hydrogen sulfate is converted into chromium sesquioxide and sodium sulfate solutions with high additional values, the problem of poison of waste is solved, and efficient recycling of chromium and sodium hydrogen sulfate is achieved; in addition, the method is simple in process, low in cost and suitable for industrial production.

The application discloses a method for preparing chromium acetate from chromium hydroxide, which comprises the following steps: mixing chromium hydroxide wet filter cake with sulfonic acid group-chromium oxide composite mesoporous silica balls according to a proportion, adding glacial acetic acid, and then carrying out reaction, heating, separation, concentration crystallization and drying to obtain high-purity chromium acetate. The sulfonic acid group-chromium oxide composite mesoporous silica ball modified material is prepared by the following steps: first, synthesizing a mesoporous silica ball base by using a template agent, then loading chromium oxide and grafting a mercapto group by silanization, and finally oxidizing to obtain a sulfonic acid group functionalized material. The material can selectively adsorb impurity ions in situ in the reaction, so that the traditional complicated purification steps are simplified. The application has the advantages of simple operation, high product purity, and good industrial application prospect.