1332 results about "Hexavalent chromium" patented technology

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.

An organic coating composition is described, which can be used to enrich the surface region of a metal-based substrate with aluminum. The composition comprises an aluminum-based powder and at least one organic resin, e.g., alkyds, epoxies, or silicone materials. At least some of the aluminum-based powder is in the form of substantially spherical powder particles. The coating composition is substantially free of hexavalent chromium. It can be applied to the substrate by a variety of techniques, such as spraying. It is then heat-treated, to cause diffusion of aluminum into the surface region of the substrate, e.g., a turbine engine component. The composition exhibits good thermal and chemical stability for extended periods of time. Related articles are also described.

A laser-based method of removing a coating from a surface comprises directing a laser pulse to a first position on the surface, removing the coating from the first position by rapidly elevating a surface temperature of the first position using the laser pulse and thereby disassociating the coating from the surface and collecting the disassociated coating. In some embodiments, the coating comprises an environmentally harmful substance such as Hexavalent Chromium. In some embodiments, the coating comprises Diamond-Like Carbon (DLC), Vitrified Contaminant Material (CMAS). The disassociated coating is collected by a waste collector.

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.

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.

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.

The invention discloses a transforming solution for preparing anti-corrosion compound oxidation film on an aluminum alloy surface and a using method for the oxidation film. The invention is characterized in that, the transforming solution is a film-forming promoter containing rare-earth salt (nitrate or sulfate and compound salt of cerium, praseodymium, and neodymium), such compound oxidant as radical of permanganate, nitrate and perchlorate, etc., film-forming promoter of vanadium salt and strontium salt, etc.; the transforming solution contains no sexavalent chromium, is environmental friendly; the reaction speed is improved by the compound oxidant and the film-forming promoter, no heating is needed for the chemical transforming, the treating time is 1-5 min. The invention can rapidly prepare under room temperature compound oxidation film comprising compound rare-earth oxide, alumina and manganese oxide with good resistance to corrosion on aluminum alloy surface. The treating solution from the invention is of rapid film-forming speed, simple process, even film layer, high resistance to corrosion, and low environmental pollution, etc.

Provided is a heavy metal treating agent and a heavy metal pollutants treating method. The invention provides a medicament and a treating method thereof. The medicament is used for treating heavy metal pollutants, like burning ash and fly ash discharged from a garbage burning field, soil polluted by heavy metal, sludge generated from waste water treatment, and heavy metal contained in the waste water discharged by factories. Heavy metal treating agent comprising piperazine dithiocarboxylic acids salt and reductible composition is used. In terms of reductible composition, water soluble bivalent iron compound and aliphatics Alpha - hydroxycarboxylic acid and/or salt, or sulfurated bi-alkali metal salt are preferably used. With the heavy metal treating agent, harmful cation species heavy metal like lead, zincum, cadmium, mercury, arsenic, selenium, and hexavalent chromium can be treated by encapsulation in a high concentration, and harmful anion species heavy metal like hexavalent chromium, arsenic and selenium can be treated by encapsulation in a high concentration.

Exemplary compositions and methods for reducing hexavalent chromium in cementitious compositions involve the use of a liquid additive composition, comprising stannous chloride. Along with the stannous chloride may be used at least one co-additive comprising an antioxidant, oxygen scavenger, or mixture thereof, and/or at least one agent comprising a cement grinding aid, cement quality improver, or mixture thereof.

Compositions and methods for increasing grinding efficiency of cement, cement clinker, raw materials for cement, and other inorganic particles. Use of biomass-derived polyols such as diols, triols, or mixtures thereof, optionally with a conventional grinding aid, cement quality improver, and/or hexavalent chromium reducer, are believed to provide less risk of sludging when compared to glycerides obtained from fossil fuel sources.

The invention discloses a method for separating and recycling chromium from the waste residue containing hexavalent chromium. The waste residue containing hexavalent chromium which has fine particles and is difficult to subside is added with mineralizer and then is subject to hydrothermal method or heating treatment to generate the waste residue which can subside, the upper clear liquid is separated from the waste residue and then the waste residue is cleaned and dried. Sodium bicarbonate or salt-mixture of sodium carbonate and sodium bicarbonate is adopted as mineralizer. The invention has simple process, low cost, quick results, large throughput, complete detoxification and no secondary pollution and can make use of all the residue, thereby bringing comparatively high social benefit and economic benefit.

The invention relates to a method for recovering hexavalent chromium resources from chromium slag. The method comprises the following steps of: subjecting chromium-containing slag to wet-process ball milling to obtain chromium slag powder, and adding water into the chromium slag powder to prepare chromium slag slurry; adding acid into the chromium slag slurry to prepare a chromium slag slurry solution, and simultaneously stirring the chromium slag slurry solution sufficiently to ensure that the chromium slag slurry is leached in the acid; subjecting the leached chromium slag slurry to solid-liquid separation to obtain hexavalent-chromium-containing filtrate, and adding acid into the hexavalent-chromium-containing filtrate; and adding a reducing agent into the hexavalent-chromium-containing filtrate added with the acid, adding base, washing and filtering to finally recover chromium hydroxide. By adopting the method for recovering the hexavalent chromium resources from the chromium slag, 60-80% of the hexavalent chromium resources can be recovered from the chromium slag, the total chromium residual amount in the chromium slag can be greatly reduced, and the residual amount of hexavalent chromium in the filtrate subjected to separation of the chromium hydroxide is below 0.5mg/L.

A water-based surface-treating agent for metallic materials which gives a film highly satisfactory in corrosion resistance, blackening resistance, wet secondary adhesion to topcoatings, low-pollution characteristics (amount of fixed chromium), chemical resistance (especially acid resistance and alkali resistance), etc., while retaining the intact practical liquid stability of conventional chromate-containing resinous coating agents. The water-based surface-treating agent comprises a synthetic resin emulsion and hexavalent chromium ions and has a pH of 5 or lower, the synthetic resin emulsion being one obtained by emulsion-polymerizing the following ingredients using a nonionic polymerizable emulsifier and a nonionic nonpolymerizable emulsifier: (1) an ethylenic carboxylic acid, (2) a functional acrylic monomer having at least one of N-((un)substituted methylol)carbamoyl, phosphonate, alkoxy, cyano, and carbamoyl groups, and (3) a third monomer which is different from the ingredients (1) and (2) and forms the skeleton of the copolymer to be obtained.

The invention discloses a treatment method of chromium-polluted soil, which comprises the following steps of: 1, adding a ferrous iron salt solution in the chromium-polluted soil, uniformly stirring to ensure that a ferrous iron salt reacts with hexavalent chromium in the soil, and reducing the hexavalent chromium in the soil into trivalent chromium; and 2, adding a lime solution in the soil obtained from the step 1, and uniformly stirring to ensure that the trivalent chromium in the soil is converted into chromium hydroxide. The high-concentration chromium-polluted soil is treated by using an in situ curing/stabilizing method, thus the treatment method is rapid and efficient, is simple in operation, and is especially suitable for in situ emergence treatment of chromium pollution accidents caused by paroxysmal heavy environmental contamination events. The curing/stabilizing rate reaches above 99 percent.

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.

The present disclosure provides an identification process which may employ various identification techniques on Zero platinum group metal (ZPGM) catalyst systems, in order to identify responsible materials for the formation of corrosion material, such as hexavalent chromium compounds. Identification analysis, such as X-ray diffraction analysis (XRD), X-ray fluorescence (XRF), and X-ray Photoelectron Spectroscopy (XPS) may be performed on various thermally treated ZPGM catalyst systems, such as in bare substrate, substrate with one type of ZPGM in washcoat, a substrate with one type of ZPGM in overcoat and substrate combination of ZPGM metals in both washcoat and overcoat. Results of identification analysis may show that regardless of metal catalyst (for example Ag, Cu, Ce), hexavalent chromium (Cr⁶⁺) may be formed on aged catalysts systems, which may be due to the high concentration of chromium in substrate. Therefore, corrosion and production of hexavalent chromium may initiate from elements found in the substrate and not from elements within the ZPGM metal catalysts.

A calcium-sodium polysulfide chemical reagent and methods for producing the reagent. The reagent is a blend of calcium polysulfide and sodium polysulfide that can be prepared using various types, sources and ratios of lime, elemental sulfur and sulfide ion using either virgin or waste materials. The reagent is amenable to inexpensive and high rate production methods at ambient or warmer temperatures. The reagent can be used to precipitate metals from wastewater, stabilize hexavalent chrome in hazardous waste residues, remove mercury from coal fired power plants, and as an electrolyte in large-scale bromide/polysulfide electrical storage batteries

The present invention relates to surface treatment of aluminum alloy, and especially a kind of chromium-free chemical aluminum alloy converting solution capable of endowing aluminum alloy surface with excellent corrosion resistance and its usage. The chromium-free chemical aluminum alloy converting solution consists of silicate, titanium salt, peroxide, fluoride, and water solution of sulfuric acid. The solution is used in 50-99 deg.c and pH 4-9 and has aluminum alloy contacting time of 2-20 min. The solution contains no hexavalent chromium and potassium ferricyanate, and has less environmental pollution, low cost, easy filming and high corrosion resistance.

A trivalent chromium electroplating solution in accordance with the present invention contains at least one trivalent chromium salt for electroplating a chromium coating layer on a workpiece. By using the low toxic trivalent chromium to substitute highly toxic hexavalent chromium, an electroplating process of the present trivalent chromium electroplating solution has less pollution.

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.

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.

The invention relates to a manufacturing process of the semi-vegetable tanned wrinkled leather of cow leather, which comprises the working procedures of initial tanning, deacidifying, vegetable tanning, filling and dry finishing. In the method provided by the invention, firstly tanning is carried out on raw hide by a small quantity of chromium tanning agent and then by a vegetable tanning agent, thereby under the premise of guaranteeing the quality of the leather, greatly reducing the content of chromium in tanning waste liquid, lightening the pollution of the chromium to the environment and effectively inhibiting the generation of hexavalent chromium through the vegetable tanning agent in the leather; and meanwhile, the granule surface of the leather is tightened through the working procedures of dry finishing and coating, and natural winkles are formed on the granule surface, thereby covering the injury of the granule surface of the leather and improving the additional value of the leather.

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.

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.

The invention discloses a batch hot-dip galvanizing chromium-free passivator and an application method thereof. According to the invention, toxic and harmful hexavalent chromium and trivalent chromium used in a traditional passivation process are replaced with an organic film-former, so that a chromium-free passivator which does not contain chromates, can be used at room temperature, is low in cost, good in corrosion resistance and easy to use, and can be practically applied to industrial production is provided for passivation treatment in the batch hot-dip galvanizing industry. The chromium-free passivator mainly comprises an organic film-former, an organic corrosion inhibitor, an oxidant, a surfactant and water. The chromium-free passivator disclosed by the invention is easy to use and simple in operation, and has no change in existing processes.

Corrosion resistant coatings are formed on aluminum by contacting with aqueous solutions containing trivalent chromium ions and fluorometallate ions, the solutions being substantially free of hexavalent chromium. Trivalent chromium films formed on the aluminum surface when tested in 5% NaCl salt spray chamber showed corrosion resistance in excess of 168 hours. Trivalent chromium coated aluminum also serves as an effective base for paint primers.

A slurry coating composition is described, which is very useful for enriching the surface region of a metal-based substrate with aluminum. The composition includes colloidal silica and particles of an aluminum-based powder, and is substantially free of hexavalent chromium. The slurry may include colloidal silica and an alloy of aluminum and silicon. Alternatively, the slurry includes colloidal silica, aluminum or aluminum-silicon, and an organic stabilizer such as glycerol. The slurry exhibits good thermal and chemical stability for extended periods of time, making it very useful for industrial applications. Related methods and articles are also described.

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.

A corrosion-inhibiting pigment comprising a rare earth element and a valence stabilizer combinded to form a rare earth/valence stabilizer complex. The rare earth element is selected from cerium, terbium, praseodymium, or a combination thereof, and at least one rare earth element is in the tetravalent oxidation state. An inorganic or organic material is used to stabilize the tetravalent rare earth ion to form a compound that is sparingly soluble in water. Specific stabilizers are chosen to control the release rate of tetravalent cerium, terbium, or praseodymium during exposure to water and to tailor the compatibility of the powder when used as a pigment in a chosen binder system. Stabilizers may also modify the processing and handling characteristics of the formed powders. Many rare earth-valence stabilizer combinations are presented that can equal the performance of conventional hexavalent chromium systems.

A black galvanized steel sheet including a composite coating layer formed on a surface of a blackened galvanized steel sheet by applying a treatment solution containing a phosphate ion, a vanadate ion, a metal ion, an α,β-unsaturated carboxylic acid and a glycoluril resin; and an organic resin layer formed on the composite coating layer, is provided. The black galvanized steel sheet is excellent in heat absorption and heat dissipation, electrical conductance, and corrosion resistance in a worked portion. Furthermore, the black galvanized steel sheet does not include hexavalent chromium.