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2774 results about "Hexavalent chromium" patented technology

Hexavalent chromium (chromium(VI), Cr(VI), chromium 6) is any chemical compound that contains the element chromium in the +6 oxidation state (thus hexavalent). Virtually all chromium ore is processed via hexavalent chromium, specifically the salt sodium dichromate. Approximately 136,000 tonnes (300,000,000 lb) of hexavalent chromium were produced in 1985. Additional hexavalent chromium compounds are chromium trioxide and various salts of chromate and dichromate, among others. Hexavalent chromium is used in textile dyes, wood preservation, anti-corrosion products, chromate conversion coatings, and a variety of niche uses. Industrial uses of hexavalent chromium compounds include chromate pigments in dyes, paints, inks, and plastics; chromates added as anticorrosive agents to paints, primers, and other surface coatings; and chromic acid electroplated onto metal parts to provide a decorative or protective coating. Hexavalent chromium can be formed when performing "hot work" such as welding on stainless steel or melting chromium metal. In these situations the chromium is not originally hexavalent, but the high temperatures involved in the process result in oxidation that converts the chromium to a hexavalent state. Hexavalent chromium can also be found in drinking water and public water systems.

Stabilized curing agent for heavy metal contaminated soil or solid waste treatment and treatment method

The invention discloses a stabilized curing agent for heavy metal contaminated soil or solid waste treatment and a treatment method. The stabilized curing agent comprises the following components in parts by weight: 5 to 10 parts of a magnesium-based compound, 1 to 5 parts of a sulfur-based compound and 1 to 3 parts of an activated silicon-based compound. The treatment method comprises the following steps of sampling inspection, experimental determination of adding proportion, mixing, backfill maintenance, sealing up for safekeeping and the like. The stabilized curing agent disclosed by the invention has an efficient long-term stabilizing effect on various heavy metals such as arsenic, mercury, hexavalent chromium, lead, cadmium, nickel, tin and cyanide, the repeated acid and alkali leaching experiments prove that the stabilized and cured harmful heavy metals cannot be dissolved out again, and the defects that in the traditional technology, the treatment effect and treatment agents are greatly affected by the environment, the long-term efficacy of harmless stabilization is poor, the medicament adding amount is difficult to control and the re-dissolution of harmful heavy metals is easily caused by the high alkalinity of cement solidification and the like are overcome.
Owner:GUIZHOU MEIRUITE ENVIRONMENTAL PROTECTION TECH

High temperature resistant environment-protective polychloroethylene material for electric wire and cable

The invention provides a high-temperature resistant environment-friendly polyvinyl chloride material for wires and cables. A raw material formulation mainly comprises the following materials in weight portion: 80 to 120 portions of loose-type polyvinyl chloride resin, 20 to 55 portions of tetraoctyl pyromellitate, 5 to 35 portions of polyester plasticizer and 12 to 18 portions of calcium-zinc stabilizer, wherein the polymerization degree of the loose-type polyvinyl chloride resin is between 2,000 and 3,000; in the calcium-zinc stabilizer, the total content of lead, cadmium, mercury and hexavalent chromium is less than or equal to 10 ppm of the total weight of the calcium-zinc stabilizer; the polyester plasticizer is polypropylene-1, 2-glycol adipate or polypropylene-1, 3-butylene terephthalate; and the molecular weight of the polyester plasticizer is between 3,000 and 4,000. After the material is aged in a hot-air oven for 168 hours at 158 DEG C, the retention rate of tensile strength is up to 106 percent; the retention rate of elongation at break is 97 percent; and the material is good in mechanical physical properties and insulating property. Therefore, the material meets the temperature-resistant requirement on long-term operating temperature at 125 DEG C in UL1581.
Owner:中广核三角洲(江苏)塑化有限公司

Film coating process for aluminium alloy wheel hub

The invention discloses an aluminum alloy wheel hub coating technology. The aluminum alloy wheel hub coating technology comprises the procedures of oil removing, cleaning and drying, pre-treating, epoxy polyester powder spraying and solidifying, grinding I, methyl methacrylate-acrylate copolymer paint spraying and solidifying, grinding II, polybutadiene high temperature resistant insulating coating spraying and solidifying, vacuum cathode arc ion chromium plating and magnetism control sputtering aluminum plating, and polyurethane methacrylate light solidifying paint spraying and solidifying in sequence. The aluminum alloy wheel hub coating technology adopts dry electric plating to replace the traditional wet electric plating, the plating layer surface quality and the physical and chemical properties are approximately equivalent to the wet electric plated aluminum alloy wheel hub, the chromium consumption is reduced to about one fifth of the wet electric plating, the water consumption is reduced to about one seventh of the wet electric plating, precious nickel and copper are not utilized, the poisonous metal substance such as hexavalent chromium is not contained, the pollution to the environment is reduced, the energy, water and precious metal consumption is remarkably reduced, the technological flow is simplified, the production efficiency is enhanced, the heavy polishing working sequence is omitted, the working condition is remarkably improved, and the cost is reduced.
Owner:HUZHOU JINTAI PLATING IND

Acid-resistant magnetic chitosan microspheres as well as preparation method and application thereof

The invention relates to an acid-resistant magnetic chitosan microsphere adsorbent as well as a preparation method and the application thereof, and in particular relates to acid-resistant magnetic chitosan microspheres which have the excellent absorption performance and recycling performance for acid waste water containing hexavalent chromium, a preparation method of the acid-resistant magnetic chitosan microspheres and the application of the acid-resistant magnetic chitosan microspheres. The preparation method of the acid-resistant magnetic chitosan microspheres comprises the following steps: (1) preparing Fe3O4 nano-particles modified by citric acid by using a coprecipitation method; (2) preparing single-coated magnetic SiO2 nano-particles by using a sodium silicate hydrolysis method or a sol-gel method; and (3) preparing the chitosan microspheres coated with magnetic SiO2 by taking chitosan powder as a raw material by adopting an emulsion crosslinking method. Furthermore, in order to further improve the adsorbing capacity of the microspheres, in the method, dendritic polyethylene imine is taken as a functional group for modifying the adsorbent, so that the modified chitosan microspheres can be obtained. The magnetic chitosan microspheres prepared by adopting the method not only have the excellent acid resistance, but also have the good absorption performance on Cr (VI) ions.
Owner:INST OF PROCESS ENG CHINESE ACAD OF SCI

Chromium-free composite passivator for hot-dip galvanized steel sheet and preparation and application methods of composite passivator

The invention relates to a chromium-free composite passivator for a hot-dip galvanized steel sheet. The passivator is prepared from the following raw materials in percentage by weight: 2.20-2.30% of water-base resin, 2.60-2.65% of main salt compound, 0.10-0.15% of organic silane, 0.07-0.09% of sulfate, 0.11-0.13% of inorganic zircon salt, 0.09-0.12% of inorganic acid and the balance of water. A preparation method of the passivator comprises the following steps: firstly, dissolving the organic silane in water; stirring till the organic silane is fully dissolved and adding the main salt compound; after the main salt compound is dissolved, adding the inorganic acid to measure the pH value; then, adding the sulfate and the inorganic zircon salt in the stirring state; after the sulfate and the inorganic zircon salt are fully dissolved, adding the water-base resin; stirring till the water-base resin is fully dissolved; adjusting the pH value to 3-4 by virtue of ammonium water; and standing for later use. An application method of the passivator comprises the following steps: firstly, degreasing the hot-dip galvanized steel sheet by virtue of an alkaline degreaser during use; then, respectively washing by using tap water and deionized water; and after drying, coating the composite passivator on the surface of the hot-dip galvanized steel sheet. The passivator provided by the invention is free from chromium and non-toxic and harmless. The thickness of a passivation film can reach 8-1.0mg/m<2>, and the corrosion resistance is close to that of a hexavalent chromium passivating liquid.
Owner:唐山正元管业有限公司

Method for preparing foam ceramic self-insulation wall material by utilizing solid wastes

The invention relates to a method for preparing a foam ceramic self-insulation wall material by utilizing solid wastes. The wall material comprises a main material and an admixture. The main material is prepared from the following components in proportion: 25% to 35% of chromium slags, 19% to 27% of coal gangue, 20% to 26% of waste ceramic polishing residues, 17% to 25% of albite and 1% to 6% of bentonite. The method comprises the following steps of: adding 16 to 20g of the admixture into every 200g of the main material; evenly mixing and screening the mixture; putting the mixture into a die; molding the mixture in a pressing manner and drying; sintering the mixture under a strong reducing atmosphere at the temperature of 1120-1180 DEG C, thereby obtaining the foam ceramic self-insulation wall material. The carbon in the coal gangue can serve as a foaming agent or a reducing agent, so that hexavalent chromium is reduced into chromium sesquioxide at the high temperature and under the strong reducing atmosphere. Thus, the toxicity of the chromium slags is eliminated. The prepared foam ceramic self-insulation wall material is low in pyroconductivity, small in density and low in water absorption rate; the usage temperature can reach 900 DEG C. In addition, the foam ceramic self-insulation wall material is complete in fire resistance, high in strength and long in service life, and can be used for replacing the existing wall materials and flammable insulation materials. The wall material integrates protection and thermal insulation functions; an exterior wall insulating layer is not required. Thus, the construction cost is lowered.
Owner:HENAN COAL CHEM IND GROUP INST +1

Preparation method and electroplating method of normal-temperature environment-friendly sulfate trivalent chromium electroplating liquid

The invention provides a preparation method and an electroplating method of normal-temperature environment-friendly sulfate trivalent chromium electroplating liquid, which relates to electroplating liquid and electroplating technology. The invention solves the problems of poor stability of the traditional trivalent chromium electroplating liquid, low precipitating and depositing rate of harmful gas in an electroplating process, more components of the electroplating liquid, sensitivity for impurities, poor corrosion resistance of an electroplating layer, and the like. The normal-temperature environment-friendly sulfate trivalent chromium electroplating liquid mainly comprises the following components of main salt, a complexation stabilizing agent, a combined additive, a buffering agent and a conducting salt. The electroplating liquid can work at normal temperature, thereby saving energy resources and having simple technology and high deposition rate, wherein the deposition rate can reach above 0.22micron.min<-1> under 6A / dm<2>. An anode of the invention is a Ti-based rare-metal tantalum-iridium-titanium anode, the anode oxygen-evolution overpotential is low, and harmful hexavalent chrome can not be generated. The normal-temperature environment-friendly sulfate trivalent chromium electroplating liquid has good corrosion resistance and high stability.
Owner:HARBIN INST OF TECH

Pretreatment process of chromium-containing wastewater

The invention relates to a pretreatment process of chromium-containing wastewater, which comprises the following steps that: 1) scrap iron filter tank is established, iron-containing spare is mixed with carbon-containing particles and porous filler to form a scrap iron filter tank after being washed by alkali so as to remove the oil and being washed by acid to remove the rust and to be activated; 2) chromium-containing wastewater is introduced into the scrap iron filter tank to be undertaken the micro electrolysis reaction after being aerated by an adjusting tank, and pH value and the oxidation reduction potential level ORP value are adjusted by acid liquid, so major hexavalent chrome is reduced to trivalent chromium; 3) the water which is discharged from the filter tank is guided to a reaction tank, neutralizing agent is added, heavy metal complex-precipitation happens, and discharged water is guided into a sedimentation tank; 4) after the majority of heavy metal pollutant inside the sedimentation tank is removed, the upper clean liquid is undertaken the advanced treatment and is discharged after reaching the standard. The pretreatment process not only realizes the resource utilization of waste scrap iron and waste acid liquid, but also greatly reduces the cost of the medicine, reduces the quantity of the following mud, and is easier to realize the resource utilization of the produced mud.
Owner:BAOSHAN IRON & STEEL CO LTD

Treating fluid and method for preparing vanadium-zirconium composite conversion coatings with self-repairing performance on aluminum alloy surfaces through same

The invention belongs to the technical field of chemical materials, and relates to a treating fluid and a method for preparing vanadium-zirconium composite conversion coatings with self-repairing performance on aluminum alloy surfaces through the same. The method includes the steps of firstly preparing the treating fluid containing fluorozirconate, metavanadate, sodium fluoride, nitrate, an accelerate and an additive; then putting an aluminum alloy after surface pretreatment into a working fluid made of the diluted treating fluid for 2min-10min; and finally subjecting the aluminum alloy to washing, drying and cooling to obtain the vanadium-zirconium composite conversion coatings. The preparation process is simple, heavy metals such as hexavalent chromium and nickel are not contained, the environment is friendly, the conversion coatings of the aluminum alloy after a conversion coating treatment are dense and high in binding force, metal ions in the conversion coatings can bond with base metal under a corrosion environment and provided with a certain self-repairing performance, and the treating technology of vanadium-zirconium conversion coatings can effectively replace chromate treatment on aluminum alloy surfaces.
Owner:湖南松井先进表面处理与功能涂层研究院有限公司

Method for detoxicating chromium residues and comprehensive utilization of detoxicated chromium residues

The invention relates to a method for detoxicating chromium residues and the comprehensive utilization of the detoxicated chromium residues. The method for detoxicating the chromium residues comprises the following steps of: performing wet ball milling on chromium-containing waste residues to obtain chromium residue powder; adding water into the chromium residue powder to prepare chromium residue slurry; adding acid into the chromium residue slurry to prepare chromium residue slurry solution, and fully stirring the chromium residue slurry solution simultaneously to make the chromium residue slurry immersed in the acid; adding a reducing agent into the immersed chromium residue slurry solution until hexavalent chromium does not exist in the immersed chromium residue slurry solution; curing the chromium residue slurry solution without the hexavalent chromium, and performing solid-liquid separation; and drying and grinding filter residues to obtain the detoxicated chromium residues without the hexavalent chromium. By the method for detoxicating the chromium residues, various hexavalent chromium compounds contained in the chromium residues can be systematically and completely detoxicated and removed, the hexavalent chromium in various produced building material products is comprehensively utilized, and the content of extract is less than 0.1mg / L.
Owner:刘杰

Method for processing chrome wastewater

The invention improves the reduction-precipitation process of traditional hexavalent chrome wastewater, changes the pH value of the trivalent chromium ion precipitation in the original process, and avoids the problem that the treated yielding water does not reach the mark caused by that the trivalent chromium precipitation is oxidized newly to generate the hexavalent chrome when performing the settlement and the filtering under the alkalescence condition. When avoiding the trivalent chromium is easily oxidized under the alkalescence condition, the adding quantity of reducing agent can be effectively reduced when reducing the hexavalent chrome. During the settlement procedure of the trivalent chromium ion in the process, the originally required precipitation pH value range 8.5-9.5 is changed, and the pH value range is adjusted to 6.0-6.3. After the settlement and the filtering, an adsorption unit is added. Treated earthnut shells are adopted to be used as a sorbent, so the trivalent chromium ion left in the solution after the adsorption and the filtering can be effectively adsorbed to lead the discharging of the yielding water to reach the mark. The sorbent containing the adsorption adopts acid solution with the pH value being 2-3 for the elution, and eluant can enter into a reduction reactor for adjusting the pH value of raw water.
Owner:NANJING UNIV
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