78 results about "Chromic sulfate" patented technology

The invention discloses a method for treating chromite by sulfuric acid leaching, which comprises the following steps of: grinding the chromite into mineral powder, adding sulfuric acid into the mineral powder, stirring the mixture, and adding an oxidant into the mixture, wherein the oxidant is chromic anhydride, potassium chlorate or ammonium persulphate, and the adding amount of the oxidant is 0.2 to 7 percent of the mass of the mineral powder; heating the mixture at the temperature of between 120 and 190 DEG C for 30 to 90 minutes under the pressure of between 0.2 and 1.2MPa, filtering the reaction products after the reaction is finished, and performing solid-liquid separation, wherein the filter residue is directly used as a raw material for melting silicon iron; and removing iron from the filtrate to obtain chromium sulfate solution, and further preparing chromium sulfate by a direct crystallization method. Compared with the prior art, the method has the most remarkable characteristics of short process flow and no 'three-waste' emission. The filter residue does not contain hexavalent chromium, and the weight of the filter residue is light and only about 10 percent of the weight of the chromite, so the filter residue can be used as the raw material for melting the silicon iron.

The invention discloses a method for synthesizing 3-methyl-4-nitrobenzoic acid by using a stepped heating method and an indirect electrosynthesis method. The method is implemented by taking 2,4-dimethylnitrobenzene and chromium sulfate as main raw materials through the following steps of: firstly, carrying out electrolytic oxidation on chromium sulfate by using an electrolytic process so as to obtain chromium trioxide; then, selectively oxidizing 2,4-dimethylnitrobenzene into a 3-methyl-4-nitrobenzoic acid by using chromium trioxide through using the stepped heating method. According to the invention, through adopting the stepped heating method, the oxidation reaction rate of 2,4-dimethylnitrobenzene is controlled, and the selectivity and conversion rate of reaction are remarkably improved. The conversion rate of chromium trioxide obtained by using an electrolytic oxidation method is 85-95%, and the conversion rate of 3-methyl-4-nitrobenzoic acid obtained by using the stepped heating method can reach 65-86%. According to the invention, the problem that in the process of reaction, the reaction rate declines due to the consumption of acids is solved; through carrying out electrolytic oxidation on chromium sulfate produced after reaction, chromium trioxide is circularly produced, thereby not only avoiding the environment pollution, but also greatly saving the cost.

The invention relates to a high-salt-fog-resistance aluminum product passivator which is an environment-friendly passivator having excellent adhesive force and high corrosion resistance, remarkably prolonging the corrosion resistance time and containing no phosphate, nitrite or other toxic heavy metal ions. The aluminum product passivator mainly comprises the following components: fluozirconate, chromic sulfate, sodium hydroxide, fluoride salt, nitrate, nickel salt and water. A preparation method of the aluminum product passivator comprises the following steps: mixing the fluozirconate and the fluoride salt, dissolving in water; fully dissolving the chromic sulfate in water of 70-75 DEG C, then adding into the former solution, and evenly mixing; and then, sequentially adding the sodium hydroxide, the nitrate and the nickel salt into the mixed solution, evenly stirring, and adding water to a specified volume, thus obtaining the aluminum product passivator. The method is simple to operate and short in processing time; and the aluminum product passivator can be repeatedly used. Thus, the cost can be saved.

This invention is for the protection and surface treatment of aluminum, aluminum alloys and coated aluminum substrates against corrosion. The aluminum substrates are treated with an acidic aqueous solution containing small but effective amounts of at least one trivalent chromium salt such as a trivalent chromium sulfate, at least one alkali metal hexafluorazirconate such as potassium hexafluorozirconate in combination with small but effective amounts of at least one water soluble or dispersible thickening agent such as a cellulose compound and at least one water soluble surfactant. The corrosion resistant aluminum substrates of this invention have improved adhesion for overlaying coatings e.g. paints and a lower electrical resistance contact.

The invention relates to a method for producing chromic oxide from carbon ferrochrome which is a novel method that is basically different from the chromic oxide preparation technique. The method comprises the following steps: by using carbon ferrochrome with fewer impurity varieties as the raw material, dissolving in a sulfuric acid solution to obtain a chromic sulfate-ferrous sulfate acid hydrolysis solution, efficiently separating chrome and iron in the acid leaching solution by using an ammonium salt efficient iron removal technique, carrying out chrome precipitation, washing and calcination on the purified chromic sulfate solution to obtain a chromic oxide product, keeping the temperature of the chrome precipitation slag, converting with an alkali medium, calcining to obtain an Fe-Cr pigment, and carrying out evaporative crystallization on the ammonium sulfate solution subjected to chrome precipitation to obtain the ammonium sulfate solid. The novel method uses the ferrochrome as the raw material to form an efficient pollution-free chromic oxide preparation technique and synchronously obtain the Fe-Cr pigment and ammonium sulfate product. The technical line has the characteristic of diversified products. The invention provides an environment-friendly economical method for producing chromic oxide, and has wide application prospects.

The invention discloses a method for preparing industrial gelatin and industrial protein powder by using waste leftover materials of leather, and belongs to the technical field of leather waste recycling. The method comprises the following steps of alkali soaking and cleaning-pickling-water washing-extracting, the leather leftover materials are soaked in alkali to form chromium hydroxide flocculent precipitate by most chromium and hydroxide radical ions in the leather leftover materials, wherein the removal rate reaches more than 98%; the residual heavy metal chromium in the leather leftover materials can be removed by acid washing to generate soluble chromium sulfate salt; water washing is carried out to remove a small amount of impurities remaining in the inner layer of the skin and opena skin fiber interstitial channel, and the water washing is carried out until the pH value is neutral; in the extraction process, the upper layer glue solution is concentrated and used for preparingindustrial gelatin, and the residual precipitate is subjected to secondary extraction and is concentrated and used for preparing industrial protein powder. According to the invention, the leather leftover materials can be effectively treated, the environmental pollution and the treatment cost are reduced, industrial products are formed, the economic benefits are generated, and the economic and social benefits caused by changing waste into valuable are achieved.

The invention relates to an iron filings surface modifier and a method for preparing an alpha-Fe<(1-x)>Cr<x>OOH active layer. The surface modifier comprises the following components in percentage by mass: 30-50% of polyethylene butyral resin, 3-10% of chromium sulfate, 3-10% of ferric oxide, 0.2-2% of sodium phosphate, 0.5-5% of sodium dodecylsulfonate, and the balance water. The modification is performed by the following steps: (1) performing degreasing cleaning on waste iron filings; (2) performing surface modification in the iron filings surface modifier; and (3) cleanly rinsing the surfacewith water after the surface modification is completed, and then performing natural air-drying. Compared with the prior art, the method uses iron filings as a raw material, and the surface of the iron filings is modified by an appropriate chemical method, so that surface components of the iron filings have catalytic ozone activity, and a dense structure to protect the iron filings matrix, the total iron content in outlet water is reduced, the catalyst's dissolution loss is inhibited, and thereby the method is a feasible way to reduce the catalyst cost of an advanced oxidation method and improve the outlet water quality, and has important practical value.

The invention discloses a nickel-chromium-copper-cobalt alloy electroplating solution which comprises 10-20 g / L nickel sulfate, 23-38 g / L nickel nitrate, 12-18 g / L chromic sulfate dodecahydrate, 8-12 g / L copper sulfate hexahydrate, 1-3 g / L cobalt acetate, 5-9 mL / L brightening agent, 0.2-0.5 g / L ascorbic acid and 6-10 g / L citric acid. The pH value is 5-6. The electroplating solution has favorable stability; by adding the copper, chromium and cobalt, the corrosion resistance of the electroplated coating is enhanced, and the coating can not easily shed; and the addition of the cobalt salt can enhance the gloss of the nickel coating.

The invention discloses a high-efficiency environment-friendly pulse plating metallurgy method for performing thick chromium plating based on trivalent chromium in a sulfate system. The method is characterized by comprising the following steps: dissolving rare earth oxides in an acid, so as to obtain a rare-earth salt solution; dissolving chromium sulfate salt, aluminum sulfate, boric acid, a complexing agent and methanol with water, and adding the rare-earth salt solution, so as to obtain a chromium sulfate salt-aluminum sulfate-boric acid-complexing agent-methanol-rare-earth salt plating solution; electroplating a to-be-plated plating piece into the electroplating solution; controlling the electroplating process conditions as follows: the distance between a pulse electroplating power supply and a plating tank is 2-3m, a wire refers to a multi-stranded core wire, and an anode refers to a Cu-matrix coating electrode plate; the current density of a connecting wire is 28-90A / dm<2> and needs to be far higher than the average current, the pH value of the electroplating solution is 2-4, the temperature refers to 25-60 DEG C, the stirring speed is 100-600rpm, the plating time refers to 30-90 minutes, the pulse frequency refers to 100-500Hz, and the duty ratio is 5-100 percent; and washing the plating piece subjected to complete electroplating, and airing. The method disclosed by the invention has the advantages of coating flatness and compactness, good adhesiveness, high current efficiency, high environmental friendliness and the like.

The invention discloses a rare earth neodymium containing trivalent chromium blue and white passivation liquid and a preparation method thereof. Every liter of rare earth neodymium containing trivalent chromium blue and white passivation liquid comprises 15-20g of chromium sulfate, 2.0-3.0g of sodium nitrate, 6.0-8.0g of cobaltous sulfate heptahydrate, 2.5-4.0g of sodium hypophosphite, 0.5-0.8g of citric acid, 0.15-0.25g of ammonium bifluoride, 0.14-0.42g of neodymium nitrate and the balance of deionized water. The preparation method comprises steps of under a continuously stirring state, firstly dissolving chromium sulfate into part of deionized water, then sequentially adding citric acid, sodium hypophosphite and sodium nitrate and dissolving, adding cobaltous sulfate heptahydrate and fully dissolving, finally adding ammonium bifluoride and neodymium nitrate, adding the balance of deionized water, standing for 24 hours so as to obtain the rare earth neodymium containing the trivalent chromium blue and white passivation liquid. After a zinc plating piece is passivated by the passivation liquid, a bright, uniform and compact blue and white passivation membrane with good corrosion resistance can be formed.

The invention discloses a blue passivator for steel parts and a preparation method thereof. The blue passivator comprises the following raw materials in parts by weight: 150 to 220 parts of chromium sulfate, 80 to 120 parts of nano silica sol, 20 to 30 parts of malonic acid, 70 to 80 parts of sodium hydroxide, 100 to 120 parts of cobalt sulfate, 40 to 50 parts of citric acid, 10 to 20 parts of sodium nitrate, 20 to 30 parts of nitric acid, 30 to 40 parts of sulfuric acid, 10 to 20 parts of sodium fluoride and a proper amount of deionized water. According to the blue passivator for the steel parts provided by the invention, after the nanoscale silica sol is added, micropores of a passivating film layer can be filled with the nanoscale silica sol, so that a prepared film layer is thick, pores of the passivating film are sealed, and the corrosion resistance of the passivating film is greatly improved.