604results about "Nitric acid" patented technology

An apparatus and method produces nitrate ions on-site from water, natural gas and air extracted in proximity to the apparatus. The apparatus generates nitrate ions and brings the nitrate ions into contact with an aqueous system. Hydrogen sulfide present in the aqueous system is removed and the production of hydrogen sulfide by sulfate-reducing bacteria (SRB) is eliminated by introducing into the system nitrate ions, whereby denitrifying microorganisms, using nitrate, outcompete the sulfate-reducing bacteria for the available carbon nutrients, thus preventing the SRB from producing hydrogen sulfide. Nitrate ions generated by the apparatus and added to the aqueous system which contains the denitrifying microorganisms can enhance oil recovery by means of microbial enhanced oil recovery mechanisms.

The invention discloses a process for preparing ultrapure nitric acid. The method comprises the following steps of: adding nitric acid metal salt to react with impurity anions, namely Cl<-> and SO4<2-> in industrial nitric acid serving as a raw material, precipitating, performing membrane filtration purification, rectifying to remove inorganic salt, regulating rectification liquid to form 69 to 70 weight percent nitric acid by using ultrapure water, white-blowing by using purified air in a white-blowing tower, absorbing blown nitrogen oxide by using saturated aqueous solution of sodium hydroxide, adding white-blowing liquid into a crude product groove, and performing membrane filtration to obtain the ultrapure nitric acid. The detection shows that: the content of the ultrapure nitric acidprepared by the process reaches 69 to 70 weight percent and various indexes of the product all meet the semiconductor equipment and material international (SEMI) C8 standard. The rectification is performed and waste acid is collected simultaneously, and the waste acid is treated and recycled, so that the quality and productivity of the product are improved; and the product has stable quality, lowimpurity content and high purity and is suitable for large-scale and continuous production.

An improved process for either the manufacturing of nitric acid, recycling of nitric acid, or recovering of nitric acid, comprising the steps of: providing a source of NOx; reacting NO from the source of NOx with HNO3 in the presence of NO2- to produce a resulting product; and reacting the resulting product with O2 and H2O to produce nitric acid.

The invention discloses a method for recovering nitric acid by pyrolyzing nitrate. The method comprises the following steps: (1) conveying the nitrate into at least two preheaters, heating the nitrateto firstly liquefy the nitrate, and then heating the nitrate to a temperature less than decomposition temperature in order to obtain a nitrate hot fluid; (2) conveying the nitrate hot fluid into a decomposer, and heating the nitrate hot fluid with a high temperature gas to maintain the internal temperature of the decomposer at 500-800 DEG C in order to decompose the nitrate into a mixed gas and asolid powder; and (3) separating mixed gas and the solid powder, conveying a part of the mixed gas into a nitric acid recovery tank, heating the remaining mixed gas to 500-800 DEG C, and then returning the heated remaining mixed gas into the decomposer to heat the nitrate hot fluid in order to thermally decompose the nitrate hot fluid. The method for recovering nitric acid has the advantages of less corrosion damages to devices, no introduction of other impurity components and no interference in the heating process, good decomposition speed and decomposition rate of the nitrate, and high recycling rate of the nitric acid.

The invention discloses a production method for a by-product alpha-hemihydrate gypsum of wet-process phosphoric acid. The method comprises the following steps: adding ground phosphate rock and a part of dilute sulfuric acid into an extraction tank, carrying out an extraction reaction, separating a clear liquid from obtained mixed slurry, using the clear liquid as a finished product phosphoric acid, sending the phosphoric acid into an acid pool, and transferring a separated solid and residual mixed slurry into a crystal transformation tank together; adding sulfuric acid and a crystal transformation agent into the crystal transformation tank, carrying out a crystal transformation reaction at 60 to 130 DEG C for 1.5 to 7.5 h, subjecting obtained mixed acid slurry to solid-liquid separation, and subjecting the obtained solid to drying so as to obtain gypsum powder or adding water into the solid without drying so as to prepare gypsum products like gypsum boards, gypsum building blocks and gypsum members. The production method provided by the invention improves traditional technology and the prior art, eliminates discharge of phosphogypsum and acid non-soluble substances, reduces the content of phosphorus in gypsum, improves the utilization rate of phosphorus, makes full use of dilution heat of concentrated sulfuric acid and realizes energy saving and emission reduction.

A joint production method of dilute nitric acid and concentrated nitric acid comprises the following steps: superazeotropic nitric acid with the mass concentration greater than 68.4% is produced by a dual-pressure dilute nitric acid production device, then concentrated nitric acid with the mass concentration greater than 98% is produced by a superazeotropic nitric acid distillation and rectification technology, and dilute nitric acid with the mass concentration greater than 60% is produced at the same time by matching. According to the production method, ammonia and air are employed to produce concentrated nitric acid, ammonia is oxidized at medium pressure, nitrogen oxides are absorbed at high pressure, the content of NOx in the exhaust gas after absorption is less than and equal to 30ppm after ammonia reduction reaction, the problem of environmental pollution is solved, and dilute nitric acid and concentrated nitric acid in any proportion and any concentration can be simultaneously produced without pure oxygen and any other dehydrating agent.

Carbon dioxide is purified by processes employing NOx-rich sulfuric acid that can be formed by removal of SO₂ from the carbon dioxide.

The invention discloses a recycling process of tin-removing waste liquid. The method includes the steps of S1, feeding the tin-removing waste liquid into a distilling device, and performing pressure reduction distillation under the temperature of 65-80 DEG C and the pressure of (0.2-0.5)*1.03*10<5>Pa to recycle nitric acid; S2, feeding distillation residual liquid into an electrolytic tank with an ion exchange membrane for electrolysis, controlling current density and cathode potential to recycle copper in the residual liquid through electrolysis, acquiring tin dioxide at the anode of the electrolytic tank, and acquiring metal copper at the cathode of the electrolytic tank; S3, controlling current density to be unchanged after metal copper is recycled, and changing cathode potential to recycle tin through electrolysis, constantly adding sulfuric acid solution in a cathode chamber during the electrolysis process until the electrolysis is ended, acquiring the tin dioxide at the anode of the electrolytic tank, and acquiring metal tin at the cathode of the electrolytic tank, wherein the current density is 100-200A/m<2>. The recycling process has the advantages that no chemical reagent is added, and secondary pollution is avoided.

The invention relates to the field of industrial waste treatment, in particular to the field of hydrometallurgical production which requires nitric acid as an oxidant, and discloses a method and a device for preparing the nitric acid through metal nitrate pyrolysis. The method includes the steps of pyrolyzing metal nitrate powder in a closed device to generate O2, NO2 and metal oxide powder, injecting the obtained O2 and the obtained NO2 into a absorption tower, and circularly absorbing the O2 and the NO2 by absorption liquid in the absorption tower to obtain the nitric acid with the requiredconcentration. The device and the method have the advantages that the whole system is sealed with positive pressure, nitrate is fully pyrolyzed in a rotary kiln, the gases generated in the process arecompletely absorbed by the liquid in the absorption tower, and almost no waste gas and waste water are discharged; the nitric acid concentration can meet hydrometallurgical production requirements, high recovery of the nitric acid is realized, the production cost of the nitric acid is reduced greatly, and recycling of metal nitrate is achieved effectively at the same time.

The invention relates to a process for continuously producing extra high purity nitric acid, which comprises the following steps: first, industrial grade 80-90% nitric acid raw material and double allyl 18-crown-6 ether organosilicon macromolecular complexing agent accounting for 0.2-2% of the weight of nitric acid raw material are mixed in a pretreater, then, the mixture is filtered by a micro-filtration membrane under a working pressure of 0.1-0.2 Mpa, the filtrate enters a rectification tower, and the semi-finished product going through the rectification tower is diluted by ultra pure water in a dilution device; after the dilution is finished, the dissociative NO2 is expelled by high pure nitrogen in a whitening device, and the obtained finished product is filtered by a nanometer filter membrane and enters a finished product receiver under the working pressure of 0.5-0.8 Mpa; wherein, the aperture of the micro filtration membrane is 0.2 to 0.8 Mu m, and the aperture of the nanometer filter membrane is 0.5 to 1.5 nm. In the prepared ultra high purity nitric acid, the content of single cation is lower than 1 ppb, the content of single anion is lower than 100 ppb, and the content of the dust particle larger than 0.5 Mu m is lower than 5 per milliliter. The production process for extra high purity nitric acid has the advantages of simple technique, low production costs, high purity of products, low content of impurity ions, and applicability for large-scale mass production.

Ammonia in a gas stream comprising oxygen and nitrogen may be effectively completely oxidized to a mixture of NO and NO₂ for further processing to nitric acid. The gas stream is flowed over fine particles of La_1-xSr_xCoO₃ and/or La_1-xSr_xMnO₃, and/or La_1-xSr_xFeO₃ where x=about 0.1, 0.2, or 0.3. The particles are supported as catalyst layers on gas stream-contacting surfaces of a flow-through catalyzed oxidation reactor. These relatively inexpensive perovskite-type materials may be used to promote oxidation of ammonia at temperatures below about 450° C. to about 500° C. to selectively produce a mixture of NO and NO₂. This mixture is suitable for further oxidation to NO₂ for adsorption into water to make nitric acid.

The invention discloses a nitric acid production technology with a double-pressurized method. The technology includes the steps of: (1) mixing of raw materials; (2) operation of an ammoxidation reaction; (3) thermal recovery and cooling; (4) absorption; (5) bleaching; and (6) treatment of tail gas. The production technology is reasonable and simple, and has high ammonia utilization rate, low platinum consumption, high absorptivity, high concentration of finished acid, and low content of NOx in the tail gas. Moreover, the production technology avoids wasting of energy resources, is suitable for promotion in various nitric acid manufactures, and has good thermal recovery so that the steam is more than self-sufficient.

The invention relates to a method utilizing the primary aluminum lime to produce the fluoride-bearing Beta alumina used on the aluminum electrolytic bath. The invention is characterized in that the process is to add the primary aluminum lime into the water with a weight of 1 to 3 times of the aluminum lime for immersion cleaning, filtering and dehydration; vapor the solution after the filtering and dehydration to obtain the mixture crystallization of the NaCl, the KCl and the NaF; add the dehydrated aluminum lime into the dilute hydrochloric acid solution for sufficient mixing; stir the solution for 3 to 5 hours at a temperature of 80 to 100 DEG C to generate the NH3 and the Al(OH)3; calcine the Al(OH)3 generated after the hydrolysis to prepare the fluoride-bearing Beta alumina. The invention has the advantages that the produced fluoride-bearing alumina has higher activation and can dissolve in the electrolyte very well and be used for electrolysis production; not only the environment pollution generated by the aluminum lime during the preparation of the primary aluminum can be solved, but also the industrial waste can be transformed to the resource for full utilization.

An indium leaching method from indium sulfide concentrate ore pertains to the smelting technique of indium extracting, in particular to the smelting technique of recovery and utilization to the independent indium sulfide concentrate ore. The method has steps that: the indium sulfide concentrate ore, sulfuric acid solution and nitric acid solution are added into a reactor container to do oxidation and dissolution and obtained indium sulfide is added into liquid; then indium is distilled and separated out through extraction, stripping, replacement technologies; meanwhile sulfur and iron concentrating in leaching slag are recovered after reaction. The invention can directly recover and utilize the independent indium sulfide concentrate ore, can simplify the smelting technology and strengthen the process, and the invention is characterized by high metal recovery rate, easy indium separation, low reagent consumption and valuable metals centralization and low pollution.

The invention belongs to the technical field of organic chemical nitrification reactions, and relates to a method for reclaiming nitric acid from nitrified waste acid. The method comprises the following steps of: adding a nitrified raw material into the nitrified waste acid, starting to stir, heating to a reaction temperature, and maintaining the reaction until the nitric acid in the nitrified waste acid is completely transformed; standing, and separating organic matters and the waste acid; and adding the organic matters into mixed acid for secondary nitrification, raising the temperature and maintaining the temperature until the reaction is completely performed. The method is used to remove oxynitride in the waste acid by recycling the nitric acid in the nitrified waste acid, so that corrosion of equipment is reduced; and the consumption of the nitric acid in the nitrifying process is reduced, and the production cost is reduced. According to the invention, the dose of the nitric acid in the nitrification reaction is reduced by sufficiently utilizing the nitric acid component in the nitrified waste acid; and the waste acid is concentrated after the nitric acid in the waste acid is reclaimed, and the corrosion of the oxynitride generated in the waste acid reclaiming process to reclaim equipment is reduced.

Methods and apparatus for the integration of a water splitting process with the production of fertilizer precursors such as ammonia, nitric acid, and sulfuric acid are provided. At least one of heat and electricity from a power plant are used to split water into hydrogen gas and oxygen gas. Nitrogen gas is provided by air separation. The hydrogen gas and nitrogen gas are used to produce ammonia. The ammonia and oxygen gas are used to produce nitric acid. The oxygen gas, water, and sulfur are used to produce sulfuric acid. Further disclosed is an apparatus for the production of nitric acid comprising a power plant and an apparatus for the production of nitric acid. Also disclosed is an apparatus for the production of sulfuric acid comprising a power plant and an apparatus for the production of sulfuric acid.

Methods and apparatus utilizing hydrogen peroxide are useful to reduce NOx, SOx and mercury (or other heavy metal) emissions from combustion flue gas streams. Continuous concentration of hydrogen peroxide to levels approaching or exceeding propellant-grade hydrogen peroxide facilitates increased system efficiency. In this manner, combustion flue gas streams can be treated for the removal of NOx, SOx and heavy metals, while isolating useful by-products streams of sulfuric acid and nitric acid as well as solids for the recovery of the heavy metals.

The invention provides a recovery method of benzene series nitration waste acid. The recovery method includes: mixing waste acid from a benzene series nitration reaction process with activated carbon for decolorizing, adding decolorized waste acid and solid potassium nitrate into an intermittent reactive distillation column bottom sequentially, heating to 60-70 DEG C with stirring for 0.5-3 hours, performing rectification operation while reaction is conducted, collecting overhead distillate, namely recovery liquid, adding water into the intermittent reactive distillation column bottom, heating with stirring to dissolve residues in the bottom, regulating a pH value of 1.4-2.1 by a potassium hydroxide water solution, filtering immediately, naturally cooling filtrate to separate out solids, filtering to obtain potassium bisulfate and recycling mother liquor. The recovery method of the benzene series nitration waste acid has the advantages that the waste acid is utilized effectively to obtain nitric acid required by the reaction and the high-added-value potassium bisulfate, so that the whole technological process is more environment friendly.

The invention discloses a method for preparing super-pure nitric acid. The method comprises the following steps: taking industrial nitric acid as a raw material; performing first stage filtration by a membrane filter consisting of dibenzo-18-crown-6 and solid-phase carrier composite membrane; performing second stage serial continuous rectification on the filtrate; collecting heavy waste acid and light waste acid respectively; and performing second stage filtration with the membrane filter to obtain the super-pure nitric acid serving as the target product. Upon analysis and detection, the content of each metal ion impurity is less than 1ppb, the dust particles bigger than 0.5microns are less than 5/ml and the SEMI C8 standard is met. By performing the second stage filtration with the membrane filter consisting of the dibenzo-18-crown-6 and the solid-phase carrier composite membrane, the method overcomes the disadvantage of instable quality of the product in an existing method; the method effectively improves the purity of the super-pure nitric acid product by using the second stage serial continuous rectification technology; and the super-pure nitric acid product obtained by the method has stable quality and high purity and is suitable for scale continuous production.