22 results about "Sodium chromate" patented technology

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 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 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 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 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 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 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 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.

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

This invention provides a method for recovering vanadium, chromium, and sodium from a vanadium-chromium sodium salt solution: (1) Adjusting the pH value of the vanadium-chromium sodium salt solution, adding a chromium precipitation agent and performing a first hydrothermal reaction to obtain chromium hydroxide product and chromium precipitation mother liquor; sequentially performing a first washing and a first heat treatment on the chromium hydroxide product to obtain chromium oxide product; (2) Adjusting the pH value of the chromium precipitation mother liquor, adding a vanadium precipitation agent and performing a second hydrothermal reaction to obtain vanadium dioxide product and vanadium precipitation mother liquor; sequentially performing a second washing and a second heat treatment on the vanadium dioxide product to obtain vanadium pentoxide product; (3) Mixing the first washing residue from step (1), the second washing residue from step (2), and the vanadium precipitation mother liquor, and evaporating and crystallizing the resulting sodium-containing solution to obtain sodium carbonate product. This method avoids the introduction of sulfur and ammonia nitrogen from the source, generates no chromium-containing solid waste, and has a short process, clean process, and low energy consumption.

The invention discloses a method for circularly and continuously neutralizing a carbonization solution in sodium chromate production, which comprises the following steps: adding the carbonization solution into a sodium chromate alkaline solution or slurry for continuous neutralization, and then washing with a filter to obtain a sodium chromate neutral solution and filter residues; adding a carbonization solution into the sodium chromate neutral solution for acidification pretreatment to obtain a pretreatment solution, evaporating the pretreatment solution, introducing CO2 for carbonization, filtering a carbonization product with a filter, and washing with hot water to obtain a carbonization solution and sodium bicarbonate; and adding the carbonized solution into a new sodium chromate alkaline solution or slurry, carrying out continuous neutralization and washing with a filter to obtain a sodium chromate neutral solution, and repeating the operation to realize cyclic continuous neutralization of the carbonized solution in sodium chromate production. The method is simple to operate, the generation of chromium-containing sodium sulfate in the existing sodium bichromate production process can be reduced, the environmental protection risk and the production cost are reduced, the produced by-product sodium bicarbonate returns to a calcium-free roasting system to replace part of sodium carbonate to participate in batching, and industrial green production is facilitated.

The invention relates to a method for producing sodium chromate by using ferrochrome dedusting ash and calcium-free chromium slag, which comprises the following steps: adding a reaction device at a flue gas outlet of a ferrochrome smelting furnace, automatically feeding back and introducing oxygen according to the detected carbon monoxide content, and increasing the content of Na2CO3 in the dedusting ash generated by ferrochrome smelting; a mixture of the fly ash and the calcium-free chromium slag is used as a raw material, pulverized coal is used as a fuel, roasting and clinker leaching are performed in an oxygen-enriched environment, and then the chromium slag is dried for ferrochrome smelting. According to the method, the sodium chromate production process is optimized, the investment of the traditional raw materials of the chromium ore powder and the sodium carbonate is reduced, the resource recycling rate is increased, the production cost is reduced, the content of hexavalent chromium in the finally obtained chromium slag is greatly reduced, detoxification is easy, and pollution is small.

The invention discloses a high-valued utilization method of chromium-containing sodium hydrogen sulfate, which comprises the following steps: step 1, adding chromium-containing sodium hydrogen sulfate into a sodium chromate neutral solution for dilution, and uniformly stirring to obtain a diluent; 2, mixing the diluent with the calcium-free roasting alkaline leaching slurry, carrying out a neutralization reaction, filtering, and washing to obtain a sodium chromate neutral solution and filter residues; wherein a part of the sodium chromate neutral solution is returned to the step 1 to dilute the chromium-containing sodium hydrogen sulfate, and the rest part is used for acidizing and converting to generate sodium bichromate. According to the method, the chromium-containing sodium hydrogen sulfate is returned to the calcium-free roasting leaching system and is continuously neutralized with the calcium-free roasting alkaline leaching slurry, so that the acid value, hexavalent chromium and trivalent chromium of the chromium-containing sodium hydrogen sulfate can be efficiently recovered and utilized in a high-valued manner, aluminate impurities are effectively removed, the leaching rate is increased, and the band loss of the hexavalent chromium is reduced; according to the method, benefits are increased, and the environmental protection problems such as secondary pollution are solved.

The invention discloses a method for preparing high-purity sodium chromite by a low-temperature solid-phase method based on a hydroxide precursor and atmosphere gradient regulation, which comprises the following steps: adding sodium hydroxide and chromium hydroxide into deionized water to prepare slurry, and carrying out ball milling and spray drying under the protection of inert atmosphere to form a spherical precursor; heating the precursor in a nitrogen atmosphere in stages to obtain a dehydrated product; a dehydration product is transferred into a second-section temperature zone, mixed gas of hydrogen and argon is introduced firstly, the temperature is increased to 600-850 DEG C at the speed of 3-5 DEG C / min, and calcination is conducted for 3-5 h; switching to a pure nitrogen atmosphere, cooling to 500-600 DEG C at the speed of 1-2 DEG C / min, and calcining for 1-2 hours to obtain a calcined product; and cooling to room temperature under the protection of inert gas, carrying out graded crushing by adopting gas flow, and then sequentially carrying out supercritical CO2 washing, deionized water ultrasonic washing, centrifugal separation and vacuum drying to obtain the high-purity sodium chromite. The method has the advantages of being high in universality, economical, capable of saving energy, high in product purity and consistency and environmentally friendly.