Showing papers on "Sodium dichromate published in 2018"
TL;DR: Sodium dichromate is an essential solution additive for the electrocatalytic production of sodium chlorate, assuring selective hydrogen evolution and the serious environmental and health concerns.
24 citations
TL;DR: In this article, the anodized film of aluminum alloy was composed of an inner thin compact layer (the barrier layer) and an outer thick porous layer, and the sealing process was done by using sodium dichromate (Na2Cr2O7) potassium dichromates (K2Cr 2O7), and boiling water, respectively.
12 citations
22 Jun 2018
TL;DR: In this paper, a model system with ex situ formed chromium oxide/hydroxide films was used to study hypochlorite reduction and hydrogen evolution and the experimental results demonstrate that the reduction is fully blocked while hydrogen evolution readily occurs.
Abstract: Chlorate production is a highly energy demanding industrial process, where chlorate formation is accompanied with hydrogen formation on the cathode. To ensure a high cathodic current efficiency, sodium dichromate is added to the chlorate electrolyte to avoid reduction of hypochlorite formed as a reaction intermediate in the process. However, chromate is highly toxic to humans and environment, and therefore a replacement is desired. A model system with ex situ formed chromium oxide/hydroxide films were used to study hypochlorite reduction and hydrogen evolution. The experimental results demonstrate that the hypochlorite reduction is fully blocked while hydrogen evolution readily occurs. However, in the presence of hypochlorite the hydrogen evolution reaction is inhibited. By combining experimental findings with density functional theory (DFT) calculations, the mechanism of hypochlorite reduction was revealed and the reason for inhibition by the deposited chromium(III) film was demonstrated. Based on these results possible replacements for chromate are suggested.
9 citations
Patent•
23 Jan 2018
TL;DR: In this article, a method for separating the vanadium and the chromium from vanadium-chromium slags was proposed, which is beneficial for effectively realizing cleanly and efficiently recycle of vanadium resources in the slags.
Abstract: The invention relates to the metallurgy field of vanadium and chromium, in particular to a method for separating the vanadium and the chromium from vanadium-chromium slags. The method is beneficial for effectively realizing cleanly and efficiently recycle of vanadium and chromium resources in the vanadium-chromium slags, and comprises the following steps of a, mixing vanadium-chromium slag powder,sodium carbonate and aluminum salt, and preparing into a vanadium-chromium slag pellet; b, roasting the vanadium-chromium slag pellet to obtain a clinker pellet; c, carrying out water leaching on theclinker pellet, carrying out solid-liquid separation on a leached slurry, and obtaining a vanadium-chromium solution and residues; d, adding calcium oxide for carrying out molybdenum precipitation for 50 to 120min, and obtaining crude calcium vanadate and a chromium solution; e, obtaining refined calcium vanadate and washing water containing vanadium and chromium, wherein the washing water containing the vanadium and the chromium is used for leaching the roasted clinker; and f, adopting a carbonization method on the chromium solution so as to prepare sodium dichromate, wherein a byproduct sodium bicarbonate is used as a sodium additive for roasting the vanadium-chromium slags. The method provided by the invention is particularly suitable for processes for separating the vanadium and the chromium from the vanadium-chromium slags.
4 citations
Patent•
19 Oct 2018
TL;DR: In this paper, a production method for high-grade pigment chromium oxide green is described. But the method is not suitable for the production of high-quality products and no pollution is caused; the color of the obtained chromium dioxide green product is more bright, colors close to yellow, close to green, and light color can be achieved.
Abstract: The invention discloses a production method f high-grade pigment chromium oxide green. According to the production method, sodium dichromate, ammonium sulfate (or ammonium carbonate) are taken as rawmaterials; crystallization technology is adopted to produce a ammonium dichromate and sodium sulfate (or sodium carbonate) mixed crystal, a roasting additive is added, high temperature roasting in a rotary kiln is carried out, and at last water washing impurity removing, drying, and crushing are carried out so as to obtain the chromium oxide green product. The beneficial effects are that: the uniformly reacted product is obtained through crystallization process, production and feeding are convenient; the production method is friendly to the environment, and no pollution is caused; the color ofthe obtained chromium oxide green product is more bright, colors close to yellow, close to green, and light color can be achieved, and product standards of Bayer company can be achieved, the productcan be used for replacing inported high-grade pigment chromium oxide green, the market prospect is promising, and the profit value is high.
1 citations
01 Feb 2018
1 citations
TL;DR: A single crystal of monoclinic sodium dichromate dihydrate was investigated by FTIR-spectroscopy in the spectral region of 4000-80 cm-1 to gain the oscillator parameters of the transition dipole moments of Na2Cr2O7·2H2O and by that the dielectric tensor function.
1 citations
Patent•
01 Jun 2018
TL;DR: In this article, a high temperature soda fusion liquid phase oxidation method was proposed to produce anhydrous sodium chromate and ferric oxide after the reaction, wherein a main reaction equation is: 4CrFe+4Na2CO3+XO2=4Na 2CrO4+Y(FeO.Fe3O4)+4CO2; after chilling separation, soaking solid chromate into water, filtering residuals, performing pre-carbonation with carbon dioxide for removing impurities and directly taking solution as a chromium system chemical material, or producing sodium
Abstract: The invention discloses a process method for producing sodium chromate with carbon ferrochrome with a high temperature soda fusion liquid phase oxidation method. The process method comprises the following process steps: smashing, heating and drying carbon ferrochrome for later use, transferring heated fusion liquid phase soda into a preheated vertical oxidation furnace, uniformly adding carbon ferrochrome powder into the oxidation furnace, guiding pure oxygen into the oxidation furnace for an oxidation reaction at the temperature of 1,000-1,300 DEG C, so as to generate anhydrous sodium chromate and ferric oxide after the reaction, wherein a main reaction equation is: 4CrFe+4Na2CO3+XO2=4Na2CrO4+Y(FeO.Fe3O4)+4CO2; after chilling separation, soaking solid sodium chromate into water, filteringresidues, performing pre-carbonation with carbon dioxide for removing impurities and directly taking solution as a chromium system chemical material, or producing sodium chromate tetrahydrate or anhydrous sodium chromate through concentration and crystallization, or producing sodium dichromate through deep carbonization. The process method has the advantages that an original chromium salt production process route is changed fundamentally, the technological process of production is shortened, the product quality is improved, the production and manufacturing cost can be lowered, and the processmethod is energy-saving and environmentally friendly.
1 citations
Patent•
21 Dec 2018
TL;DR: In this paper, a method for extracting vanadium and chromium from chromium-vanadium ore/slag is presented, which aims to solve the problem that vanadium is difficult to extract and separate from the vanadium-chromium paragenic ore at the same time.
Abstract: The invention discloses a method for extracting vanadium and chromium from chromium-vanadium ore/slag, and belongs to the technical field of metallurgy. The method aims to solve the problem that the vanadium and the chromium are difficult to extract and separate from the vanadium-chromium paragenic ore at the same time. The method for extracting the vanadium and the chromium from the chromium-vanadium ore/slag comprises the following steps that the chromium-vanadium ore/slag is uniformly mixed with sodium salt and calcium salt, and the mixture is oxidized and calcined to obtain a clinker; theclinker is leached by using water, and separation is carried out to obtain a chromium-containing solution and chromium extraction tailings; the chromium extraction tailings are mixed with the water, the pH value of slurry is adjusted to be 2.5-3.5, and leaching and separating are carried out to obtain a vanadium-containing solution and vanadium-chromium extraction tailings; and treatment is correspondingly carried out on the chromium-containing solution and the vanadium-containing solution so as to obtain sodium dichromate and vanadium pentoxide. According to the method, a sodium-calcium combined roasting-water leaching chromium extraction-acid leaching vanadium extraction technology is adopted, the technology is short in technological process, easy to operate, high in production efficiency and capable of obtaining high-purity chromium products and vanadium products with high yield.
1 citations
Patent•
24 Apr 2018
TL;DR: In this paper, a continuous gradient neutralization, filtration and washing method of sodium chromate alkaline solution is proposed, where a commodity sodium dichromate solution serves as a neutralization agent, and an appropriate quantity of aluminum hydroxide crystal seeds are added into the bottom materials in the four-level impinging stream reactors.
Abstract: The invention relates to a continuous gradient neutralization, filtration and washing method of sodium chromate alkaline solution. According to the method, commodity sodium dichromate solution servesas a neutralization agent, sodium chromate neutral solution is added into four-level impinging stream reactors in advance and serves as bottom materials, gradient pH (potential of hydrogen) values ofthe bottom materials in the four-level impinging stream reactors are adjusted by the aid of caustic soda, an appropriate quantity of aluminum hydroxide crystal seeds are added into the bottom materials in the four-level impinging stream reactors, the concentration and the flow of the sodium chromate alkaline solution of an upper inlet and the concentration and the flow of the neutralization agentsof an lower inlet are controlled, the temperature, a pH value, the stirring rotating speed and the outlet feed liquid flow of feed liquid in the four-level impinging stream reactors are controlled, impurities such as aluminum in the sodium chromate alkaline solution are separated out in a sedimentation manner, neutralized feed liquid enters a feed liquid storage tank and filtered and washed by apumping and filtering device, sodium chromate neutral solution and aluminum sludge are separated, the formed aluminum sludge is low in chrome belt loss and easily filtered and washed, alkaline normal-pressure leaching of the aluminum sludge can be achieved at certain temperature, and cost is low when the aluminum sludge serves as a raw material for producing chrome-free aluminum hydroxide.
Patent•
21 Dec 2018
TL;DR: In this paper, a preparation method and application of a large-particle sodium chromite material, belonging to the technical field of sodium ion batteries, is described, which comprises the following steps of putting sodium dichromate in a crucible, calcining in a reducing atmosphere, controlling calcination temperature at 800-900 DEG C, and preserving heat for 3-24 h. After the calcination is completed, cool with a furnace, and the obtained product is a NaCrO 2 material.
Abstract: The invention relates to a preparation method and application of a large-particle sodium chromite material, belonging to the technical field of sodium ion batteries. The method comprises the followingsteps of putting sodium dichromate in a crucible, calcining in a reducing atmosphere, controlling calcination temperature at 800-900 DEG C, and preserving heat for 3-24 h. After the calcination is completed, cool with a furnace, and the obtained product is a NaCrO 2 material. The large-particle NaCrO2 prepared by the method has a particle size of 10-1,000mu m, and has excellent electrochemical performance and relatively high tap density; the preparation process is simple and easy, the raw materials are cheap, the product is single, less energy is consumed, the environment is protected, large-scale production is convenient to realize, and by applying the prepared sodium chromite material, which serves as a positive electrode material, in a sodium ion battery, the obtained sodium ion battery has high specific capacity, good rate performance and excellent cycle stability.
Patent•
20 Apr 2018
TL;DR: In this paper, a method for preparing anhydrous sodium sulfate from chromium-containing mirabilite as a byproduct in the production process of sodium dichromate was proposed.
Abstract: The invention relates to the field of a chemical industry and particularly relates to a method for preparing anhydrous sodium sulfate from chromium-containing mirabilite as a by-product in the production process of sodium dichromate. The method comprises dissolving a certain concentration of chrome-containing mirabilite in chromium-containing waste water, adding quantitative sodium thiosulfate into the waste water to promote reduction of hexavalent chromium into trivalent chromium under 0.1-1 Mpa at 80-190 DEG C, wherein the trivalent chromium in a form of chromium trioxide hydrate is precipitated, adding a small amount of sulfuric acid to neutralize, filtering to acquire the chromium trioxide hydrate, removing impurities, carrying out decoloration, evaporating to precipitate anhydrous sodium sulfate crystals, and carrying out continuous centrifugal separation and drying. The method is simple and easy, utilizes cheap raw materials, has low energy consumption and a high automation degree and is suitable for large-scale production. The quality of the industrial anhydrous sodium sulfate product obtained by the method meets the requirements of class I products in the GB/T 6009-2014 industrial anhydrous sodium sulfate standard.
Patent•
23 Mar 2018
TL;DR: In this paper, a method for preparing sodium chromate by utilizing a byproduct chromium chromate generated in a sodium dichromate production process is presented, where a mixture obtained through reaction to be in heat exchange with a cold sizing agent in the material-material heat exchange, filtering and washing after reducing the pressureto normal pressure, thus obtaining a sodium chromately solution, wherein the sodium chromates can be used as a raw material for preparing the sodium dichrome.
Abstract: The invention relates to the field of chemical industry, and in particular to a method for preparing sodium chromate by utilizing a byproduct chromium chromate generated in a sodium dichromate production process. The method comprises the following steps: pulping chromium chromate and sodium hydroxide in a sodium chromate solution into a sizing agent; heating the sizing agent through a material-material heat exchanger and a sleeve heater after being filtered, and carrying out continuous oxidation reaction on the sizing agent and oxygen in a tower reactor under certain temperature, pressure andultrasonic waves; enabling a mixture obtained through reaction to be in heat exchange with a cold sizing agent in the material-material heat exchange, filtering and washing after reducing the pressureto normal pressure, thus obtaining a sodium chromate solution, wherein the sodium chromate can be used as a raw material for preparing the sodium dichromate. By utilizing the technical method disclosed by the invention, the byproduct chromium chromate in chromium salt industry can be fully reutilized, a sodium chromate product with high additional value can be produced and prepared, optimizationof the product structure of a chromium salt enterprise can be promoted, and the economic benefit of the enterprise can be increased.
Patent•
08 Jun 2018
TL;DR: In this paper, a method for preparing mica iron oxide by using chromium-containing iron slag which is the byproduct of a chromium salt wet process is presented, and the chromium recovery rate is further improved while the iron content in the high-iron slag is ensured to be 95% or above.
Abstract: The invention discloses a method for preparing mica iron oxide by using chromium-containing iron slag which is the by-product of a chromium salt wet process. The method comprises the following steps:step one, adding chromium-containing iron slag into a reaction kettle, slowly adding an alkaline solution to the reaction kettle, closing a feed port, starting stirring, then adding a gas-phase oxidizing agent, controlling the pressure of the reaction kettle to be 0.1-8.0 MPa through an exhaust valve, and carrying out a reaction for 1-5 hours; and step two, opening a pressure valve of the reactionkettle, carrying out solid-liquid separation on the material liquid obtained in the step one through a positive pressure filter, recovering the obtained lower-layer material sodium chromate alkalinesolution as a raw material for producing sodium dichromate, washing the upper-layer solid phase, and carrying out drying to obtain the mica iron oxide. The invention provides the method for preparingthe mica iron oxide by using the chromium-containing iron slag which is the by-product of a chromium salt wet process, and the chromium recovery rate is further improved while the iron content in thehigh-iron slag is ensured to be 95% or above, so that the mica iron oxide with stable crystal form and high purity is obtained, the application field of the by-product iron slag is expanded, and the economic value is increased.
Patent•
06 Mar 2018
TL;DR: In this paper, a drug containing 2,3-epoxy-2-nonyl sulfone-5,8-dimethoxy-1,4-naphthoquinone as well as a preparation method was described.
Abstract: The invention discloses 2,3-epoxy-2-nonyl sulfone-5,8-dimethoxy-1,4-naphthoquinone as well as a preparation method and a drug containing 2,3-epoxy-2-nonyl sulfone-5,8-dimethoxy-1,4-naphthoquinone andbelongs to the technical field of medicines The structural formula is as shown in the specification The method disclosed by the invention comprises the following steps: 1, dissolving 5,8-dimethoxy-1,4-naphthoquinone into methanol, adding 1-nonanethiol, reacting at a room temperature, adding sodium dichromate and concentrated sulfuric acid, continuing reacting, extracting with dichloromethane andsaturated salt solution, drying anhydrous sodium sulfate, filtering, and concentrating to be dried; 2, dissolving into chloroform, continuing adding 3-chloroperoxybenzoic acid, reacting at a room temperature, adding a 5% NaHCO3 solution after the reaction is completed, neutralizing excessive metachloroperbenzoic acid in the reaction, ending the reaction, extracting with dichloromethane and saturated salt solution, drying anhydrous sodium sulfate, filtering, and concentrating to be dried The invention further discloses application of the compounds and pharmaceutical composition in preparationof medicines for treating liver cancer
Patent•
23 Nov 2018
TL;DR: In this article, a control method of a grain diameter in production of chromium oxide green was proposed. The control method comprises the following steps: (1) preparing sodium chromate mother solutions with different sodium dichromate content by adopting a carbonization method; (2) taking the mother solutions as oxidization raw materials of hydrothermal reaction; (3) carrying out the reaction on the oxidisation raw materials and starch and filtering an obtained reaction product; then carrying out two times of countercurrent washing; controlling the content of soda in a chromium hydrate filter cake
Abstract: The invention discloses a control method of a grain diameter in production of chromium oxide green The control method comprises the following steps: (1) preparing sodium chromate mother solutions with different sodium dichromate content by adopting a carbonization method; taking the sodium chromate mother solutions as oxidization raw materials of hydrothermal reaction; (2) carrying out the hydrothermal reaction on the oxidization raw materials and starch and filtering an obtained reaction product; then carrying out two times of countercurrent washing; controlling the content of soda in a chromium oxide hydrate filter cake; (3) adding the washed chromium oxide hydrate filter cake into a high-temperature furnace and carrying out calcination to prepare the chromium oxide green; (4) collecting and dispersing the chromium oxide green obtained by the calcination through a water extraction method; washing the chromium oxide green and drying, wherein a solution generated by washing is a puresodium chromate solution Compared with a traditional method for producing the chromium oxide green through calcining chromium oxide hydrate, the method provided by the invention has the advantages that atmosphere protection is not needed and the requirements on equipment are simple; sodium salt in the filter cake is used as a mineralizing agent of a production process of the chromium oxide green,and a high-quality environment is provided for the growth of chromium oxide green crystals, so that the growth of the crystals is more regular and complete
Patent•
09 Jan 2018
TL;DR: In this paper, a device and method for treating a weak sodium chlorate solution is described, which comprises the steps that weak sodium dichromate is concentrated, and part of sodium chloride is separated by crystallization; then concentration is performed by adopting a hydraulic cyclone separator; and concentrated sodium chloride crystal slurry is subjected to dissolution and pH value adjustment and then returns back to an electrolytic system.
Abstract: The invention discloses a device and method for treating a weak sodium chlorate solution. The method comprises the steps that weak sodium chlorate is concentrated, and part of sodium chloride is separated by crystallization; then concentration is performed by adopting a hydraulic cyclone separator; and concentrated sodium chloride crystal slurry is subjected to dissolution and pH value adjustmentand then returns back to an electrolytic system. Compared with a process that a weak sodium chlorate solution is treated by means of a traditional comprehensive method chlorine dioxide preparation system under equal productivity conditions, the volume of a configured chlorine dioxide generator can be decreased, and the investment cost is lowered; and meanwhile, closed cycle of sodium dichromate between the electrolytic system and a chlorine dioxide reaction system is achieved, loss is basically avoided, no extra sodium dichromate needs to be supplemented, a chlorine dioxide solution is not contaminated, and the device and method are economical and environmentally friendly.