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1332 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

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

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 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

Surface treated steel plate excellent in corrosion resitance electroconductivity and appearance of coating film

The present invention provides a surface-treated steel sheet including a steel sheet; a plating layer provided on at least one of the surfaces of the steel sheet, the plating layer containing at least one metal selected from the group consisting of zinc and aluminum; a first layer film provided on the surface of the plating layer and containing (α) 1 to 2000 mg/m2 of silica in terms of SiO2, (β) a total of 1 to 1000 mg/m2 of phosphoric acid groups in terms of P, (γ) a total of 0.5 to 800 mg/m2 of at least one metal selected from the group consisting of Mg, Mn, and Al in terms of a metal element, and (δ) 0.1 to 50 mg/m2 of a tetravalent vanadium compound in terms of V; and a second layer film formed to a thickness of 0.1 to 5 μm on the first layer film and containing a resin (A) having at least one type of functional group selected from the group consisting of OH and COOH groups, and at least one rust-proofing additive (B) selected from the group consisting of (a) a phosphate, (b) Ca ion-exchanged silica, (c) a molybdate, (d) silicon oxide, and (e) at least one organic compound selected from the group consisting of triazoles, thiols, thiadiazoles, thiazoles, and thiurams. The surface-treated steel sheet has excellent corrosion resistance without containing hexavalent chromium in a coating, and also has excellent conductivity and coating appearance.
Owner:JFE STEEL CORP

Non-chromium treatment fluid for preparation of corrosion-resistant oxidation film on magnesium alloy surface and method of use thereof

The invention discloses a preparation and application method for conversion liquid of a corrosion resistant oxide film on magnesium alloy surface, which is characterized in that: the conversion liquid adopts rare-earth-containing salt, permanganate, persulphate, nitrate and perchlorate as composite oxidant, zirconium salt, vanadic salt and strontium salt as film forming promoter, boric acid, aminoacetic acid-hydrochloric acid solution as pH buffer regulator, pyridine, thiourea and derivatives, tannins, phytic acid and the salt compound as corrosion inhibitor, sodium dodecyl benzene sulfonate and dodecyl phenol polyoxyethlene ether (OP-10) as wetting agent; the conversion liquid is free from hexavalent chromium and environment-friendly; heating is not required for chemical conversion treatment, and the treatment time is 1 to 5min; composite oxide film with good corrosion resistance performance comprising rare-earth composite oxide, magnesia and manganese oxide can be rapidly prepared at on magnesium alloy surface at ambient temperature. The preparation method for conversion liquid of a corrosion resistant oxide film on magnesium alloy surface has the advantages of fast film forming, simple process, uniform film, strong corrosion resistance and less environmental pollution.
Owner:广州市宏盈机械设备有限公司

Circularly-tanning technology for chrome tanning liquor of sheep garment leather

The invention discloses a circularly-tanning technology for chrome tanning liquor of sheep garment leather. The circularly-tanning technology comprises the following steps: conditioning, drying, shearing, main-soaking, fleshing, degreasing, pickling, softening, disacidifying, softening, pickling, tanning, wet grinding, retanning, neutralizing, adding grease, retanning, dyeing hair, and dyeing plates. According to the circularly-tanning technology for chrome tanning liquor of sheep garment leather, the formation of hexavalent chromium can be effectively reduced, and the chrome waste liquor flocculation is omitted. According to the test on the chrome content after the chrome tanning liquor is utilized, the chrome waste liquor can be recycled repeatedly by supplementing corresponding chrome powder during next-time recycling, thereby realizing the clean production of tanned leather industry. According to the circularly-tanning technology, the sealed no-emission utilization of a chrome resource can be guaranteed so as to greatly reduce environmental pollution, effectively lower waste water emission and save enterprise waste treatment and production cost. In addition, the quality of the produced leather is consistent with that of the common chrome tanned leather, the shrinkage temperature is above 100DEG C, and a leather body is soft, plump and flexible, is colorful, has pure white hair and has no effect on the dyed hair and the dyed plates.
Owner:ZHEJIANG ZHONGHUI FUR & LEATHER +2

Two-stage countercurrent washing medicament addition stabilization combined restoration method of chromium polluted soil

The invention relates to a two-stage countercurrent washing medicament addition stabilization combined restoration method of chromium polluted soil, comprising the following steps of: (1) pouring polluted soil into fist-stage washing equipment, stirring and washing the soil with a liquid-to-solid ratio of 10:1 and then carrying out solid-liquid separation; filling separated waste water into a water treatment system, and pouring dewatered soil into second-stage washing equipment; (2) using clearing water which is treated by the water treatment system and reaches the standard as the water of the second-stage washing equipment, stirring and washing the dewatered soil with a liquid-to-solid ratio of 10:1 and then carrying out solid-liquid separation; sending separated washing liquid to the first-stage washing equipment for recycling; (3) adding FeSO4 to the soil after second-stage washing to carry out stabilization treatment, wherein the addition quantity of the FeSO4 is 1-5 percent of the soil to further reduce the content of Cr6 in the soil and reduce the pH to 6-9 meanwhile; and (4) directly backfilling the stabilized soil. The invention has the advantages of thorough elimination of hexavalent chromium pollution, low price and easy obtain of medicaments, environmental security, use function recovery of restored soil, and the like.
Owner:CHINESE RES ACAD OF ENVIRONMENTAL SCI
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