40 results about "Sodium chromate" patented technology

The present invention provides a method for producing a molybdenum-vanadium-aluminum-chromium alloy with high uniformity. The composition of the molybdenum-vanadium-aluminum-chromium alloy is as follows: Mo 25% - 28%, V 24% - 27%, Cr 28% - 31%, with the balance being Al, O ≤ 0.05%, C ≤ 0.05%, and the segregation of the main content being < 0.6%. It relates to the field of metallurgical technology. The technological steps are as follows: (1) Prepare an ammonium molybdate-ammonium dichromate-ammonium metavanadate precursor by hydrothermal method using sodium molybdate, sodium metavanadate, sodium dichromate, and ammonium chloride; (2) Perform high-temperature treatment on the precursor to obtain a MoO3 / V2O5 / CrO3 composite material; (3) Mix the MoO3 / V2O5 / CrO3 composite material, refined aluminum powder, and calcium oxide in proportion, load them into a furnace and ignite to undergo a thermite reaction to obtain a molybdenum-vanadium-aluminum-chromium alloy ingot. Compared with the molybdenum-vanadium-aluminum-chromium alloy produced by the traditional thermite method, the uniformity of the present invention is greatly improved, and it can be used for the production of titanium alloys such as TB2, TB9, TB15, and TB16.

The invention discloses a sodium dichromate production roasting tail gas dust recycling device, and relates to the technical field of boiler equipment.The sodium dichromate production roasting tail gas dust recycling device comprises a mounting frame, a driving unit, a reducing unit, an anti-blocking unit and a recycling unit, the mounting frame is used for mounting and fixing the driving unit, the driving unit is used for working of a kiln body, and the reducing unit is used for changing the filter hole diameter of a filter screen; the anti-blocking unit is used for cleaning dust accumulated on the surface of the filter screen, the recovery unit is used for recovering the dust, and when the driving unit drives the kiln body to work and sodium dichromate production roasting is carried out, the filtering hole diameter of the filter screen is changed through the reducing unit, so that the situation that dust collection is affected due to the fact that the filter screen is blocked when the flow speed is too large is avoided; and dust attached to the surface of the filter screen is scraped through the anti-blocking unit to prevent blocking, the separated dust is secondarily recycled through the recycling unit, and the utilization rate of resources is increased.

The invention discloses a preparation method and application of a sodium-ion battery positive electrode material, and relates to the technical field of sodium-ion batteries, and the preparation method comprises the following steps: (1) dissolving a compound containing a Cr element in water, adding the solution into a reaction kettle, gradually dropwise adding a NaOH solution, after the reaction is completed, gradually adding a chitosan hydrochloride aqueous solution into the reaction kettle according to a certain ratio, and stirring to obtain a mixed solution; after reacting for a certain time, filtering, washing and drying to obtain chitosan-coated chromium hydroxide Cr (OH) 3 (at) CS; (2) blending the Cr (OH) 3 (at) CS prepared in the step (1) with a sodium source according to a certain molar ratio, sintering the mixture under protective gas, and then grinding and sieving to obtain a carbon-coated sodium chromite positive electrode material NaCrO2 (at) C; the sodium-ion battery has good electrochemical performance and cycle performance, and the sustainable development of the sodium-ion battery industry is promoted.

The invention relates to a preparation method of a carbon-coated sodium chromite material and application of the carbon-coated sodium chromite material prepared by the method, and the preparation method comprises the following steps: (1) weighing a chromium source, a sodium source and a carbon source, respectively heating and drying, and uniformly mixing to obtain mixed powder; (2) putting the mixed powder into a ball mill for ball milling, and then preparing into sheets; (3) calcining in an inert atmosphere to obtain a sodium chromite precursor; (4) performing ball milling in a ball mill, and stirring in a carbon source saturated solution; (5) baking the stirred materials at a high temperature; and (6) calcining the baked product in an inert atmosphere. The preparation method is simple, low in cost and free of redundant by-products, comprehensive and complete carbon coating of the sodium chromite material is achieved through a distributed carbon coating method, side reactions are effectively prevented, the formed carbon coating layer is good in uniformity, and the service life of the sodium chromite material is prolonged. The sodium ion battery prepared from the material has high specific capacity, good rate capability and excellent cycle stability.

The present invention provides a preparation method of a structure-modified sodium ion battery positive electrode material, comprising the following steps: S1, mixing a sodium source, an iron source, a phosphorus source, a first carbon source, a structure modifier, and deionized water, adding the mixture to a high-gravity reactor rotating at 25,000 to 35,000 rpm, reacting at a temperature of 80 to 100° C. for 1 to 2 h, drying, and then calcining at 400 to 650° C. for 8 to 12 h in an inert gas atmosphere to obtain a precursor, wherein the structure modifier is at least one of sodium vanadate, sodium titanate, sodium manganate, sodium cobaltate, sodium chromate, metatitanic acid, magnesium oxide, copper oxide, zinc oxide, and yttrium oxide; S2, mixing the precursor, a second carbon source, and a chelate solution, adjusting the pH to 2.5 to 4.0, grinding the mixture at a temperature of 60 to 90° C. until the D50 is less than 0.95 μm, spray drying, and calcining at 400 to 650° C. for 8 to 12 h in an inert gas atmosphere. h obtain the structure-modified sodium ion battery positive electrode material.

The invention discloses a method for comprehensively utilizing vanadium and chromium resources, which comprises the following steps: mixing chromium hydroxide with sodium hydroxide, and introducing oxygen for liquid-phase oxidation to obtain an oxidation solution; adding calcium oxide into the oxidation liquid, stirring and mixing, and performing solid-liquid separation after reaction to obtain calcium vanadate solid and vanadium-free alkali liquid; adding a decalcifying agent into the vanadium-free alkali liquor, and carrying out solid-liquid separation to obtain calcium carbonate and refined sodium chromate alkali liquor; reacting calcium vanadate with roasting slurry containing aluminum, silicon and carbonate to form calcium aluminosilicate precipitate and desiliconized high-vanadium alkali liquor; continuously neutralizing the desiliconized high-vanadium alkali liquor and the carbonization solution to obtain an aluminum-vanadium high-valued product and a neutral solution; the neutral liquid is carbonized, and obtained sodium bicarbonate and carbonized liquid can be returned to a system for recycling. The method for comprehensively utilizing the vanadium and chromium resources has the advantages of being simple in process, environmentally friendly, efficient, easy to control in operation, easy to obtain raw materials, low in production cost and the like.

The invention provides a method and a system for recovering chromium and aluminum from a waste chromium catalyst. The method comprises the following steps: carrying out alkali fusion reaction on the waste chromium catalyst and sodium hydroxide to obtain alkali fusion clinker; mixing the alkali fusion clinker with water, pulping, leaching, and carrying out solid-liquid separation to obtain a water leaching solution containing Na2CrO4 and NaAlO2 and a filter cake containing Al2O3; adding a barium salt solution or solid into the aqueous extract containing Na2CrO4 and NaAlO2, reacting to generate a BaCrO4 precipitate, and carrying out solid-liquid separation to obtain a BaCrO4 filter cake and a sodium metaaluminate filtrate; reacting the BaCrO4 filter cake with an inorganic acid, and carrying out solid-liquid separation to obtain a chromic acid solution and a barium sulfate precipitate; and adding an acid solution into the sodium metaaluminate filtrate, adjusting the pH value to 7-8, and carrying out solid-liquid separation to obtain an Al (OH) 3 filter cake. According to the method, Cr (III) in the waste catalyst is directionally converted into Cr (VI) through an alkali fusion oxidation process, then the solubility difference of sodium chromate and sodium metaaluminate in an aqueous solution is fully utilized, the high-selectivity separation characteristic of barium chromate precipitation is combined, the chromium-aluminum separation problem is fundamentally solved, and the finally obtained product is excellent in purity.

This invention relates to the field of chromium slag resource utilization technology, specifically to a method for pre-reduction enhanced oxidation extraction of chromium from chromium slag, comprising: S1, mixing calcium-free roasted chromium slag, carbonaceous reducing agent, and sodium carbonate in a mass ratio of 1:(0.4~0.9):(0.05~0.25) and pressing them into shape to obtain a chromium slag preform; S2, under an inert atmosphere, reducing and roasting the chromium slag preform at 850~1050℃ for 30~150 min to generate sodium chromite, and cooling it to room temperature with the furnace to obtain a pre-reduced chromium slag mixture; S3, under an oxygen-containing atmosphere, oxidizing and roasting the pre-reduced chromium slag mixture at 850~1050℃ for 30~150 min to convert trivalent chromium into water-soluble hexavalent chromium compounds, and air-cooling it to room temperature to obtain a roasting product; S4, stirring and leaching the roasting product in an acidic solution, separating the solid and liquid to obtain a leaching residue and a leachate containing hexavalent chromium. The pre-reduction stage enables lattice reconstruction and micropore optimization, creating favorable reaction conditions for the subsequent oxidation stage, thereby significantly improving the oxidation conversion efficiency of chromium.

The invention belongs to the technical field of wafer processing, and particularly relates to an organic etching solution for etching a groove of a quartz wafer and application of the organic etching solution. The organic etching liquid comprises 10%-20% of hydrogen fluoride, 20%-30% of ammonium bifluoride, 40% of pure water, 10%-12% of trisodium phosphate, 4%-8% of sodium chromate and 2% of polyethylene glycol. According to the organic etching solution prepared by the invention, the stability of the tuning fork quartz frequency chip is improved, the electrical property of the tuning fork quartz frequency chip is improved, the corrosion shape of the groove can be controlled by changing the corrosion rate of different crystal faces, and the effect of improving the performance is achieved.

The invention discloses a method for preparing chromic anhydride from a sodium chromate neutral solution, which comprises the following steps: transferring the sodium chromate neutral solution into a storage tank of an anode head tank by using a pump, adjusting the temperature, transferring a sodium hydroxide solution into a storage tank of a cathode head tank, and adjusting the temperature; overflowing the sodium chromate neutral solution after temperature regulation to an anode chamber of an electrolytic bath and then overflowing to an anode circulating tank, and overflowing the sodium hydroxide solution after temperature regulation to a cathode chamber of the electrolytic bath and then overflowing to a cathode circulating tank; electrifying a cathode plate and an anode plate of the electrolytic bath with direct current to start electrolysis; pumping out an anode solution after electrolysis, adding the anode solution into a reaction kettle after evaporation, adding concentrated sulfuric acid, heating and dehydrating, and standing in a clarifier until layering; the upper layer is sodium hydrogen sulfate, and the lower layer is chromic anhydride liquid, cooling and flaking to obtain the high-quality chromic anhydride. The method can effectively shorten the production period, greatly improve the production yield, reduce the labor intensity of workers, avoid high cost of an electrolytic method and avoid a large amount of byproduct chromium-containing sodium hydrogen sulfate of a sulfuric acid method, and is economical and practical.

The application discloses a sodium dichromate production roasting waste heat recycling device and relates to the technical field of boiler equipment. The device comprises a mounting frame, a rotary kiln, a driving unit, a detection scraping unit, a waste heat recycling unit and a fixed feeding unit. The mounting frame is used for mounting and fixing the rotary kiln and the driving unit. The rotary kiln is used for sodium dichromate production roasting. The driving unit is used for power output. The detection scraping unit is used for nodular detection and scraping of the rotary kiln inner wall. The waste heat recycling unit is used for raw material temperature detection. The fixed feeding unit is used for feeding the preheated raw material into the rotary kiln. When the sodium dichromate is produced and roasted in the rotary kiln, the detection scraping unit is driven by the driving unit to detect and scrape the nodules in the rotary kiln at any time, so that uneven roasting is avoided. The raw material is preheated to a preset temperature by the waste heat recycling unit, and the raw material is fed by the fixed feeding unit, so that waste heat recycling is realized.

The application relates to the technical field of electroplating, and discloses a chromium electroplating process for improving the hardness of a connector terminal, which comprises the following steps: performing surface pretreatment on the connector terminal, removing surface impurities through ultrasonic cleaning and micro-etching treatment; performing heating treatment on the connector terminal; performing electroplating treatment on the connector terminal by using an electroplating solution comprising trivalent chromium salt, boron nitride nanoparticles, ferroferric oxide nanoparticles, nickel ions, sodium dichromate and chromium alloy additives, so as to form a chromium plating layer; performing passivation treatment on the plating layer; performing low-temperature treatment on the plating layer; and spraying a protective layer on the chromium plating layer. Through the trivalent chromium salt and the sodium dichromate, the trivalent chromium salt is used to reduce hexavalent chromium ions into trivalent chromium, the toxicity of the hexavalent chromium is reduced, the sodium dichromate is used to provide a stable chromium source, the deposition of chromium elements in the electroplating process is ensured, the pollution of hexavalent chromium to the environment and the harm of hexavalent chromium to the health of operators are solved, and the environmental protection and safety of the electroplating process are improved.

The invention discloses a method for preparing sodium chromate from chromium-containing wastewater, comprising the steps of resin activation, resin adsorption elution and resin regeneration. The method can achieve high efficiency and low cost in preparing sodium chromate from chromium-containing wastewater by selecting appropriate resin and optimizing process parameters, without secondary pollution to the environment. The treated water has good quality and meets national emission standards. Moreover, a large amount of chromium-containing compounds can be recycled and utilized, thereby generating economic benefits.

The invention discloses a method for liquid-phase decomposition of vanadium slag under low alkalinity. The method comprises the following steps: preparing a sodium hydroxide solution; adding vanadium slag into the sodium hydroxide solution, and uniformly stirring to obtain a mixed solution; adding the mixed solution into a high-pressure reaction kettle, and controlling the reaction temperature, the reaction pressure, the reaction time, the oxygen rate and the rotating speed; after the reaction is finished, the mixed solution is filtered while hot, a mixed solution of sodium vanadate and sodium chromate is obtained, vanadium and chromium in the vanadium slag are recycled into the mixed solution of sodium vanadate and sodium chromate respectively, and the purpose of recycling vanadium and chromium resources is achieved. Compared with the high temperature required by the traditional sodium salt roasting process, the reaction temperature is reduced by more than 600 DEG C, and the energy consumption is obviously reduced. The method has high vanadium and chromium resource utilization rate. After liquid-phase oxygenolysis, the content of vanadium in the tailings is 1-2 wt%, and the content of chromium is 2-3 wt%. According to the method, comprehensive high-value utilization of vanadium and chromium resources is achieved, meanwhile, generation of hazardous waste is reduced, and a high-efficiency and low-cost green production process system is constructed.

The present invention relates to a process for comprehensively recovering valuable metals from cobalt-rich waste. Cobalt silicate in the waste is converted into sodium cobalt silicate through sodium carbonate roasting pretreatment, cobalt ferrite is converted into cobaltous oxide and ferric oxide, and composite oxides of tungsten, tantalum, and niobium are converted into soluble sodium salts such as sodium tungstate and sodium chromate. These are then separated from alkaline oxides such as cobaltous oxide in a subsequent water leaching process. Cobalt, iron, and copper in the water leaching residue are leached into a solution through sulfuric acid reduction leaching, while metals such as tantalum and niobium are contained in the acid leaching residue. Tungsten and chromium in the water leaching solution are separated by concentrated hydrochloric acid neutralization followed by tungsten precipitation followed by chromium reduction precipitation. This process has the advantages of a high elemental leaching rate and high separation efficiency of cobalt from elements such as tungsten and chromium. Furthermore, the process is simple, the reaction conditions are mild, and the raw materials used are inexpensive. It can achieve comprehensive recovery of elements such as cobalt, tungsten, and tantalum.

The application provides a method for rapid detection of barium ions in oil-based drilling fluid and a method for preventing drill pipe blockage, the method for rapid detection of barium ions comprising the steps of: mixing an oil-based drilling fluid sample and a demulsification solvent, stirring uniformly to obtain a mixed solution; mixing the mixed solution with distilled water, stirring and then standing until oil and water are separated; filtering the lower water phase to obtain a colorless and clear liquid, adding a sodium chromate solution, and observing whether a yellow precipitate appears, if a yellow precipitate appears, it indicates that the oil-based drilling fluid contains barium ions, and if no yellow precipitate appears, it indicates that the oil-based drilling fluid does not contain barium ions. The method for preventing drill pipe blockage comprises: taking an oil-based drilling fluid sample to be detected to detect whether it contains barium ions; and taking preventive measures in advance to prevent the internal circulation channel of the drill pipe from being blocked in the case that it is determined that the oil-based drilling fluid contains barium ions. The application has the advantages of simple and rapid operation, low cost, and the result can be obtained within 30 min without special instruments, equipment and medicines.

This invention belongs to the field of solid waste resource utilization in the battery industry, specifically disclosing a method for utilizing chromium slag. Through steps such as mixing and grinding chromium slag and sodium-containing alkaline substances, low-temperature roasting and crystallization, water leaching, crystallization, and separation, this invention fully extracts Cr and P from the chromium slag, and separates and prepares sodium phosphate, sodium chromate, and industrial iron ore products. This achieves complete resource utilization of valuable elements in the chromium slag and solves the environmental pollution problem of chromium slag in the nickel salt production process of nickel-iron alloys.

The invention relates to the technical field of sludge treatment, and particularly discloses a resource recycling method and recycling device for chromium-containing electroplating sludge, the chromium-containing electroplating sludge is directly mixed with water, a dispergator is added for dispergation, high-pressure shearing is carried out through a homogenizer to promote slurry refinement, liquid caustic soda, a catalyst and an oxidizing agent are added, and the chromium-containing electroplating sludge is obtained at a certain temperature and pressure. Trivalent chromium in the chromium-containing electroplating sludge is oxidized into a sodium chromate solution of hexavalent chromium, and the highest oxidation rate can reach 99.9%; the method comprises the following steps: adding a low-value mixed reducing agent into sodium chromate, reducing the sodium chromate into a chromium oxide hydrate under the action of certain temperature and pressure, calcining the chromium oxide hydrate to obtain chromium oxide green, and producing barium sulfate and sodium carbonate by using the generated mother liquor, thereby implementing resource utilization of the chromium-containing electroplating sludge. According to the method, the metal recovery rate of the chromium-containing electroplating sludge can be increased, chromium, nickel, copper and iron in the sludge can be recovered, and high-purity sodium carbonate and barium sulfate can be recycled.

The invention discloses an NFPP-coated sodium chromite core-shell structure positive electrode material and a preparation method thereof, and belongs to the technical field of sodium ion battery positive electrode materials. The preparation method comprises the following steps: firstly, synthesizing a sodium chromite core material by adopting a high-temperature solid-phase method; then preparing NFPP precursor sol containing an iron source, a phosphorus source and a sodium source; the preparation method comprises the following steps: uniformly dispersing a NaCrO2 core in a sol, carrying out controllable heterogeneous nucleation and growth on an NFPP precursor on the surfaces of NaCrO2 particles by controlling the pH value and the concentration, drying, and carrying out heat treatment in an inert atmosphere to finally form a core-shell structure positive electrode material taking NaCrO2 as a core and NFPP as a shell. According to the invention, the NFPP coating layer is utilized to effectively inhibit the side reaction between NaCrO2 and electrolyte, the dissolution of transition metal and the collapse of a layered structure in the circulation process, so that the circulation stability and safety of the material are greatly improved, and meanwhile, the high voltage and high capacity characteristics of NaCrO2 are maintained.

The invention discloses a method for extracting and converting bromine ions dissolved in a water body and detecting stable bromine isotopes, and belongs to the field of isotope detection methods. The method comprises the following steps: oxidizing bromide ions in a water body by using acidic sodium dichromate based on the oxidation-reduction characteristic of the bromide ions in the water body to obtain bromine gas, reacting the bromine gas with an alkaline solution to obtain sodium bromide, adding silver ions into the solution to generate silver bromide precipitates, drying the precipitates, quantitatively putting the precipitates into a jaw headspace bottle in a dark environment, and adding methyl iodide; reacting under optimized conditions to generate methyl bromide gas; a gas isotope mass spectrometer and a gas chromatograph which are provided with receiving cups with the mass numbers of 94 and 96 are used in a combined mode, interference of impurity gas is eliminated through modified Isolink II equipment, after bromomethane mixed gas is separated through a chromatographic column, the impurity gas is emptied, bromomethane enters the mass spectrometer, and the bromine isotope ratio is accurately measured. The method can be used for evaluating and researching sources, causes and formation hydrogeochemical and physical processes of oil field water, underground brine, salt water and the like.

The application discloses a method for preparing sodium chromate by high-temperature separation and recovery of chromium slag, and belongs to the technical field of sodium chromate separation and preparation. The process comprises the following steps: adding sodium carbonate with a molar ratio close to that of chromium into the chromium slag and stirring uniformly, then, passing in air and roasting to 1200 DEG C-1400 DEG C and keeping the temperature until the weight is no longer reduced, when the temperature reaches 1200 DEG C, collecting the condensed material volatilized, namely, sodium chromate. Since the volatilization temperature range of sodium chromate is relatively wide, and the sodiumized roasting high-temperature volatilization temperature section 1200 DEG C-1400 DEG C of the chromium-iron slag has only sodium chromate, the process heating parameters can be easily adjusted and industrial control can be realized. Therefore, the method for preparing sodium chromate by high-temperature separation of chromium based on the volatilization phenomenon of sodium chromate combines the advantages of the previous processes, and has the advantages of simple process, environmental protection and remarkable economic benefits.

The invention relates to a method for recovering chromate. The method comprises the following steps: (1) adsorbing the chromium-containing wastewater by using ion exchange resin; (2) eluting and regenerating the adsorbed resin by using an alkaline solution, and collecting an eluent; (3) adjusting the pH value of the collected eluent to be acidic, and concentrating to obtain a chromate concentrated solution; (4) adding a sulfate precipitator into the chromate concentrated solution, and removing sulfate in a precipitation manner; (5) crystallizing and drying the obtained chromate solution; wherein the alkali solution is a sodium hydroxide solution, and the concentration of the alkali solution is 20-25%. According to the method, the cost required by evaporation and concentration can be greatly reduced, and the removal efficiency of sodium sulfate is improved.

The application discloses a method for in-situ transformation and chromium removal of aluminum mud in chromium salt production, and belongs to the field of chromium-containing aluminum mud resource utilization, and solves the problems of harsh process conditions, low recovery rate and difficult chromium removal in the utilization method of the chromium-containing aluminum mud.The method comprises the following steps: adding a sodium chromate alkaline solution into a reaction kettle, spraying a sodium chromate solution from the top of the reaction kettle, continuously stirring, and keeping the reaction temperature at 80-90 DEG C; keeping the pH value of the reaction slurry at 9-9.5, continuously discharging from the bottom of the reaction kettle, realizing continuous production, washing the product after filtration and separation, and obtaining the chromium-containing aluminum mud; and washing the chromium-containing aluminum mud three times by using a sodium hydroxide solution to obtain the aluminum mud after chromium removal.The application utilizes the reaction between the alkali and the chromium-containing aluminum mud by using the in-situ chemical conversion method, deeply removes the hexavalent chromium in the aluminum mud, and prepares qualified aluminum hydroxide, so that the defects of the traditional method, such as complicated process, low product quality and long production cycle, are avoided.

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 present invention relates to the technical field of sludge treatment, and specifically discloses a resource recovery method and recovery device for chromium-containing electroplating sludge. The chromium-containing electroplating sludge is directly mixed with water, and then a disintegrating agent is added for disintegration. The slurry is then sheared by a homogenizer at high pressure to promote slurry refinement. Liquid caustic soda, a catalyst, and an oxidizing agent are then added. Under a certain temperature and pressure, the trivalent chromium in the chromium-containing electroplating sludge is oxidized to a sodium chromate solution containing hexavalent chromium, with an oxidation rate of up to 99.9%. A low-value mixed reducing agent is added, and under a certain temperature and pressure, the sodium chromate is reduced to chromium oxide hydrate. The chromium oxide hydrate is calcined to obtain chromium oxide green. The resulting mother liquor is used to produce barium sulfate and sodium carbonate, thereby realizing resource utilization of the chromium-containing electroplating sludge. The present invention can improve the metal recovery rate of the chromium-containing electroplating sludge, and can not only recover chromium, nickel, copper, and iron in the sludge, but also recover high-purity sodium carbonate and barium sulfate.

The utility model discloses a kind of automatic impurity removal filter equipment in sodium dichromate continuous crystallization production, including filter box, the top of the filter box is connected with feed hopper, the bottom of the filter box is connected with discharge pipe, adjusting plate is inserted and connected and installed in the inside of the discharge pipe, the upper portion of the filter box inner chamber is installed with filter frame, the middle part of the filter frame is embedded and installed with coarse filter screen, the bottom of the coarse filter screen is installed with vibration motor.The utility model realizes two-stage filtration by setting coarse filter screen and fine filter plate, simultaneously, vibration motor is used to drive coarse filter screen vibration, driving motor is used to drive impact plate to make fine filter plate vibrate, effectively prevent filter material blockage, significantly improve the filtration speed and efficiency, meet the continuous production demand, two-stage filtration structure cooperates vibration cleaning function, can effectively intercept different particle size impurities, improve filtration precision, ensure the stability of sodium dichromate product quality.

This utility model discloses a treatment system for recovering industrial-grade sodium chromate from chromium-containing electroplating wastewater. The system is sequentially connected to a pretreatment system, an ion exchange system, an evaporation and concentration system, a purification system, and an evaporation and crystallization system. The pretreatment system removes suspended solids. The ion exchange system contains at least four ion exchange columns and an eluent tank; the coordinated operation of multiple columns ensures sufficient adsorption and elution of chromium, increasing the concentration of hexavalent chromium in the eluent, reducing the load on subsequent evaporation equipment, and shortening processing time. The evaporation and concentration system uses an MVR evaporator and integrates an online density meter. The purification system is equipped with a purification reaction vessel with a detachable pH meter probe, which can quantitatively remove sulfate, reducing the difficulty of salt separation and crystallization, increasing the number of mother liquor circulations, and thus improving the chromium recovery rate. The feed to the eluent tank allows for reasonable adjustment of the alkali dosage according to different concentrations of components, avoiding waste and reducing costs. The detachable pH meter probe facilitates maintenance, ensures accurate monitoring, and improves the stability of sulfate removal rate and the quality of sodium chromate products.

The invention relates to the technical field of sodium ion electronics, and particularly discloses a sodium chromite preparation device and method based on a mechanochemical method.The sodium chromite preparation device comprises a base, a driving disc is rotationally arranged on the base, a main ball milling tank is rotationally arranged in the middle of the driving disc, and two symmetrically-arranged auxiliary ball milling tanks are rotationally arranged on the driving disc. Through the synergistic effect of the main ball-milling tank and the auxiliary ball-milling tank, argon serving as protective gas serves as a carrier to continuously flow and dynamically carry refined chromic oxide and sodium carbonate in the auxiliary ball-milling tank into the main ball-milling tank, the continuous process of raw material pretreatment and mechanochemical reaction is achieved, material accumulation is avoided, real-time contact of reactants is ensured, and the production efficiency is improved. And the product is the sodium chromite powder under high-energy ball milling, and mechanical crushing and secondary ball milling are not required to be performed on the product, so that the production period can be greatly shortened, and the production efficiency is improved.

The invention discloses a method for removing chromium from aluminum mud through in-situ transformation in chromium salt production, belongs to the field of resource utilization of chromium-containing aluminum mud, and solves the problems of harsh process conditions, low recovery rate and difficulty in removing chromium in a utilization method of the chromium-containing aluminum mud. The method comprises the following steps: adding a sodium chromate alkaline solution into a reaction kettle, adding the sodium chromate solution from the top of the reaction kettle through spraying, continuously stirring, and keeping the reaction temperature at 80-90 DEG C; keeping the pH value of the reaction slurry at 9-9.5, continuously discharging from the bottom of the reaction kettle at the same time to realize continuous production, filtering and separating a product, and washing with water to obtain chromium-containing aluminum mud; and carrying out three times of in-situ transformation washing on the chromium-containing aluminum mud by using a sodium hydroxide solution to obtain the chromium-removed aluminum mud. Through the in-situ chemical conversion method, the alkali reacts with the chromium-containing aluminum mud, hexavalent chromium in the aluminum mud is deeply removed, the qualified product aluminum hydroxide is prepared, and the defects that a traditional method is complex in procedure, low in product quality, long in production period and the like are overcome.

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.