303 results about "Sodium dichromate" patented technology

The invention relates to a surface treatment process for stainless steel, in particular to a stainless steel passivation process. The process comprises the following steps of: dipping a stainless steel workpiece in an alkali degreasing solution for 10-30 seconds under a normal temperature condition; washing the workpiece by using water at the normal temperature; acid washing: acid washing the workpiece for 50-60 seconds by using a nitric acid solution at the normal temperature; washing the workpiece by using water at the normal temperature; soaking the workpiece in a passivation solution for 40-50 seconds at the normal temperature, wherein the passivation solution contains nitric acid and sodium dichromate; washing the workpiece by using water at the normal temperature; heating purified water to be higher than 75 DEG C, and putting and soaking the passivated and cleaned workpiece into the purified water for 4-5 seconds; taking out the workpiece and airing. The invention greatly saves the time for passivating the stainless steel workpiece, reduces the production requirements of the workpiece and ensures that the process is more suitable for practical production.

The invention relates to technology for preparing chromium oxide through hydrothermal reduction of sodium chromate or sodium dichromate, which comprises: preparing the sodium chromate or the sodium dichromate into an aqueous solution, placing the aqueous solution and starch or starch derivatives into a high-pressure reaction kettle for hydrothermal reduction, and obtaining chromic hydroxide slurry; filtering and separating the chromic hydroxide slurry to obtain chromic hydroxide filter cakes and a chromic hydroxide mother solution; and performing high-temperature roasting on the filter cakes to obtain chromium oxide products. The technology has short technological flow, simple operation, low cost and mild reaction conditions, and does not have overhigh requirements on equipment; not only the product quality is better than that of the prior method but also the reduction and conversion rate of sexavalent chromium reaches more than 98 percent; and the whole technology forms a closed cycle, realizes recycling of mixed alkali, the mother solution and a washing liquid, does not discharge pollutant in any form during the whole process, and fundamentally avoids pollution.

The present invention discloses a kind of anticorrosion mildew inhibitor for bamboo and timber material. The anticorrosion mildew inhibitor for bamboo and timber material has bamboo vinegar liquid as matrix and contains chlorthalonil, triazolone, boric acid, borax, copper sulfate, santobrite, sodium dichromate, sodium fluoride or their mixture. The anticorrosion mildew inhibitor has bamboo vinegar liquid, rather than water, as matrix, and possesses high anticorrosion and mildew inhibiting effect and less environmental pollution.

The invention relates to an improvement of a fire coal combustion improver. The improved fire coal combustion improver is characterized by being prepared by compounding and mixing the following components: 20 to 30 weight percent of dolomite powder, 5 to 15 weight percent of dicyclopentadieny iron, 3 to 10 weight percent of chromium trioxide, 3 to 10 weight percent of manganese dioxide, 3 to 15 weight percent of magnesium nitrate, 3 to 15 weight percent of sodium dichromate and/or potassium dichromate, 3 to 18 weight percent of zinc oxide, 15 to 30 weight percent of active clay. The fire coal combustion improver has a plurality of functions of combustion acceleration, sulfur solidification, smoke abatement and the like; the thermal efficiency of a boiler can be improved by 3 to 8 percent; the coal-saving efficiency is up to 5 to 15 percent; the Ringelmann smoke blackness is less than 1; the total removal rate of SO2, NOx and the like is 25 to 60 percent, and the combustion improver has remarkable coal-saving and environmental-protection effect. Since the combustion effect is improved, the inferior coal (such as coal gangue), which is difficult to combust normally, is combusted and comes into play. After the long use, the boiler is not corroded, the scaling of the calcium sulfate in the boiler can be reduced, the operation safety of the boiler can be improved and the service life of the boiler can be prolonged.

The invention provides a process for preparing sodium dichromate, namely producing the sodium dichromate through a carbonization method comprising: converting sodium chromate into the sodium dichromate via carbon dioxide under pressurizing condition; delivering sodium chromate neutral liquor with impurities removed to a carbonization tower after a cascade reaction of more than three continuous towers; obtaining carbonizing liquor by controlling different gradient parameters (concentration and temperature of the carbonizing liquor, partial pressure of the carbon dioxide, carbonizing time and the like), continuously carbonizing and separating under pressure; obtaining sodium dichromate finished products through concentrating, filtering, evaporating, crystallizing and centrifugal dehydrating.

The invention provides a boiler coal combustion-improving desulfurizing agent composition. The composition comprises the following components in parts by weight: 3-9 parts of sodium carbonate, 1-2 parts of sodium acetate, 3-9 parts of calcium carbonate, 4-9 parts of aluminium hydroxide, 2-5 parts of ferric trichloride, 3-10 parts of ferric oxide, 8-22 parts of potassium permanganate, 8-22 parts of potassium chlorate, 15-40 parts of activated attapulgite clay, 7-13 parts of manganese oxide, 4-8 parts of copper oxide, 4-8 parts of alumina, 3-8 parts of copper carbonate, 3-10 parts of zinc oxide, 3-10 parts of zinc nitrate, 4-11 parts of sodium dichromate, 0.5-1.5 parts of barium molybdate, 0.5-1.5 parts of vanadium pentoxide, 0.2-0.5 part of cerium oxide and 1-3 parts of dispersing agent JFC. The composition is an additive suitable for coal-fired boilers in the petroleum, chemical, power, thermoelectricity and metallurgy industries, can absorb and solidify sulfur dioxide generated in the combustion process, adsorbs dust and other harmful substances in quantity and simultaneously removes smoke dust scales and jelly adhering to the inner walls of combustors, thus inhibiting the concentration of flue gas emission.

The invention relates to an adjuvant for coal washing and desulfurizing. The adjuvant is prepared from the following raw materials in parts by weight: 20-25 parts of sodium hypochlorite NaClO, 12-15 parts of ammonium persulfate (NH4)S2O8, 8-12 parts of sodium glycollate HOCH2COONa, 6-10 parts of sodium acetate CH3COONa, 7-12 parts of potassium citrate K3C6H5O7H2O, 5-9 parts of sodium gluconate, 5-9 parts of edetic acid, 7-12 parts of potassium permanganate KMnO4, 25-32 parts of methanol CH3OH, 22-30 parts of triethanolamine (HOCH2CH2)3N, 12-16 parts of sodium dichromate Na2Cr2O7, 3-5 parts of polyaluminum ferric chloride PAFC,1-2 parts of urea CON2H4, 1-2 parts of polyacrylamide PAM, 0.5-0.8 part of sodium dodecyl benzene sulfonate C18H29NaO3S, 0.2-0.4 part of dispersing agent JFC and 100-120 parts of water. The adjuvant disclosed by the invention is simple to use, stable in performance and free of large investment and transformation equipment; the removal rate of inorganic sulfur and organic sulfur is more than 70 percent; and the removal rate of nitric oxides is more than 70 percent.

The utility model relates to a high-efficiency iron rust conversion agent, and belongs to the field of an antirust paint. The iron rust conversion agent comprises the following raw materials by weight: 0.1-10% of zinc oxide, 20-40% of phosphoric acid, 0.5-15% of dichromate, 0.5-10% of phosphate, 0.1-10% of corrosion inhibitor, and 50-70% of solvent, wherein the dichromate is potassium dichromate or sodium dichromate; the phosphate is sodium phosphate or potassium phosphate; the corrosion inhibitor is urotropine or urea; and the solvent is water or ethanol. The preparation method comprises the steps as follows: sequentially adding the solvent, the phosphoric acid, the dichromate, the phosphate, the corrosion inhibitor and the zinc oxide to a glass cup under persistently stirring according to the mass ratio, and dissolving for 10-20 min. The production method bases on the dissolving of the solid reactants in the phosphoric acid solution. The phosphorized film formed by iron rust conversion has the effects of preventing rust and fixing remnant rust, and the formed phosphorized layer protective film is long-acting, and stable in atmospheric environment, lubricating oil and organic solvent, has high adhesion, can be used as a primer, has dielectric properties, and can prevent electro-chemical corrosion on the metal surface.

The invention provides a profile modification agent for amphion jelly. The profile modification agent comprises the following components by weight percent: 0.1%-0.3% of amphion polymer, 0.1%-0.3% of compound cross-linking agent and the balance of water, wherein the molecule weight of the amphion polymer is above 1500 ten thousand. The compound cross-linking agent is prepared by a method comprising the following steps: firstly, adding phenol and formaldehyde in an enamel reaction kettle with a stirrer at a mass ratio of 1:1, heating and raising the temperature to 60 DEG C, then adding triethanolamine so that the phenol and formaldehyde are reacted to generate a mixture of monohydroxymethyl phenol, dihydroxymethyl phenol and trihydroxymethyl phenol for later use; next, adding sodium dichromate and thiourea in the reaction kettle with the stirrer at a weight ratio of 1:1, adding hydrochloric acid and a mixture of sodium acetate and sodium malonate which are at a weight ratio of 1:1 to react for 12 hours for later use; and mixing the products obtained from the former two steps at an isovolumetric ratio, and adding absolute ethyl alcohol for evenly stirring so as to obtain the compound cross-linking agent. According to the invention, the glue-forming property and glue-forming strength of the jelly profile modification agent in high-hypersalinity oil field water are improved, and the validity of the profile modification of the oil field is prolonged.

The invention provides a preparation method of a tin-plated plate and an application of the tin-plated plate prepared by the preparation method. The preparation method comprises the following steps that a strip steel sequentially undergoes tin plating, soft melting, passivation and oil coating to obtain a finished product, wherein in the tin plating process, the current density of the first pass and the last pass is 10-20 A/dm<2>, and the current density of the middle pass is 5-10 A/dm<2>, in the soft melting process, a pure induction soft melting process is adopted, the temperature of soft melting is 240-245 DEG C in the soft melting process, the soft melting time is 0.5-1.5 s, and in the passivation process, a sodium dichromate solution with the concentration being 27-31 g/L is used as apassivation solution. Through the preparation method, the tin-plated plate which is uniform in coating, good in welding performance, good in binding force with a PET film and extremely low in tin quantity is prepared, and the tin-plated plate can be used for replacing a chromium plated plate to be applied to the coated iron.

The invention relates to an injection well profile modification agent which comprises polyacrylamide with the molecular weight of 1-2 million, hydrolysis degree less than 5% and consistency of 0.5%, inorganic chromium salt cementing agent sodium dichromate with the consistency of 0.15-0.5%, thiocarbamide with the consistency of 0.05-0.4% and residual quantity of water. After the profile modification agent is adopted, the permeability of high permeability layer reaches 40-60% and proportion of the profile modification agent entering the destination layer can be improved from 70% to more than 95%.

The invention discloses a method for producing high-purity vanadium pentoxide by using vanadium-containing waste residues, and the method is designed for solving the problems that in the prior art, calcium slags are long in filtration time and large in washing water amount, the recovery rate of vanadium is low, the purity of vanadium pentoxide is low, and the like. The method is implemented by taking vanadium-containing calcium slags discharged in the process of sodium dichromate production as a raw material by virtue of the steps of adding a certain amount of sodium bicarbonate solution into the raw material, stirring and leaching the obtained mixture, feeding CO2 gas for deep leaching, and filtering the obtained product for impurity removal; feeding O2 into the obtained solution so as to oxidize the obtained solution, adding a concentrated sulfuric acid for adjusting the pH value of the obtained product and acidifying the obtained product, and after the obtained product is subjected to heat preservation and curing, filtering and precipitating the obtained product so as to obtain hydrous vanadium pentoxide; heating the hydrous vanadium pentoxide so as to dissolve the hydrous vanadium pentoxide, adjusting the PH value of the dissolved hydrous vanadium pentoxide, and filtering the obtained hydrous vanadium pentoxide so as to remove impurities; adding saturated ammonium chloride into the obtained solution to carry out vanadium precipitation, and filtering, washing and roasting the obtained product so as to obtain vanadium pentoxide. Compared with original methods, the method disclosed by the invention has the advantages that the washing water amount of calcium slags is reduced by 50%, the recovery rate of vanadium is increased by about 4%, and the purity of vanadium pentoxide is increased by over 99%. The utilization rate of vanadium-containing waste residues is improved, and the market competitiveness of products is enhanced.

This invention relates to preparation method of modified lignin poly carboxylic acid cement dispersant, belongs to concrete admixture. The process: whip amd heating-up lignin sulfonate to 50 to 80 deg, in turns add sodium dichromate 5 to 9 shares, polyvinyl alcohol 10 to 20 shares, acroleic acid 5 to 18 shares, initiator 0.1 to 3 shares, at temperature 80 to 100 deg, take reaction for 3 to 5 hours, gain modified lignin sulphonate water solution. The product brings the cement good consistency, not bleed air, without bleeding, good degree of fluidity and good flexibility.

The invention relates to a comprehensive detoxification and cleaning process for chromium slag by roasting and oxidation. The technical solution adopted is: a comprehensive detoxification and cleaning process of chromium slag roasting and oxidation, characterized in that: chromium slag is used as raw material, chromite and soda ash are auxiliary materials, and the material ratio is: chromium slag: chromite ore: soda ash=2:1 :0.6, at the roasting reaction temperature of 1050°C, the chromium trioxide in the mixed material is roasted and oxidized at high temperature to form sodium chromate, the conversion rate is more than 80%, and the extraction liquid is used as the mother liquor for the production of red alum sodium products. The main process flow: roasting and oxidation + ball mill leaching + plate and frame filter press dehydration + liquid production red alum sodium production + filter cake secondary beating to extract supernatant + acidification solidification + landfill or building materials. The total chromium content in the detoxification slag is low, and the comprehensive utilization rate is high, which solves the post-disposal problem existing in the traditional dry and wet chromium slag detoxification process, and the cost is low. The method is also applicable to the roasting production with calcium, less calcium and calcium-free in chromium salt production enterprises, and the effect is equally remarkable.

The invention discloses a preparation method of chlorine dioxide without production of solids. The method comprises the following steps: filtering a concentrated sodium chlorate solution sent from an electrolytic bath, then injecting into a generator to form a reaction mother solution, circulating in the generator and a circulating pipeline under the action of a circulating pump, maintaining the reaction mother solution at a certain density and temperature, then adding hydrochloric acid sent from a hydrochloric acid system, reacting to generate chlorine gas, chlorine dioxide gas and sodium chloride, cooling the chlorine dioxide gas, then absorbing the chlorine dioxide gas by low-temperature chilled water to obtain a chlorine dioxide water solution, sending the chlorine gas produced by reaction into a hydrochloric acid furnace to be burned with hydrogen gas produced in the electrolytic bath to prepare hydrochloric acid, and returning a dilute sodium chlorate solution after reaction into the electrolytic bath by a pump for re-preparing the concentrated sodium chlorate solution for recycling. According to the method disclosed by the invention, the production of the solids can be prevented in the whole reaction process and scaling of equipment can be avoided, so that sodium chloride and sodium dichromate can be completely recycled and do not need to be supplemented basically.

The invention discloses a method for jointly producing chromium salt and ferrochromium alloy by sintering with the wet-fire methods, comprising the following steps: grinding coarse ferrochromium ore into fine ferrochromium ore powder; mixing the fine ferrochromium ore powder and sodium carbonate into mixture, and sintering the mixture into primary sintered clinker; extracting primary sodium chromate solution from the primary sintered clinker and obtaining the left primary chromium slag; separating, sintering and crushing the primary chromium slag into primary chromium slag powder, and mixing the primary chromium slag powder and sodium carbonate into mixture, and sintering the mixture into secondary sintered clinker; extracting secondary alkaline sodium chromate solution from the secondary sintered clinker and obtaining the left secondary chromium slag; adding acidic solution to neutralize the alkaline sodium chromate solution; adding sodium dichromate to the sodium chromate solution, adjusting the acidifying with sulfuric acid to form sodium dichromate solution, and separating sodium dichromate crystals from the sodium dichromate solution; mixing the secondary chromium slag and iron ore with coke powder and auxiliary materials and sintering the mixture into sintered ore; and mixing the sintered ore and coke in a blast furnace to smelt the ferrochromium alloy.

The invention relates to a delayed crosslinked chromium gel profile control plugging agent, belonging to the technical field of oilfield profile control plugging. The delayed crosslinked chromium gel profile control plugging agent is formed by crosslinking partially hydrolyzed polyacrylamide and Cr<3+> generated by redox reaction. The delayed crosslinked chromium gel profile control plugging agent is composed of the following components in percentage by weight: 0.3-0.8% of partially hydrolyzed polyacrylamide, 0.02-0.20% of sodium dichromate, 0.15-0.50% of additive and the balance of water. Compared with the reported chromium gel, the delayed crosslinked chromium gel has the advantages of long gelling time, high heat stability and high gel strength. Under the optimal formula, the delayed crosslinked chromium gel has high plugging rate, favorable abrasion resistance and high practicality, and satisfies the demands for on-site construction.