33 results about "Sodium bifluoride" patented technology

The invention relates to a preparation method for hydrogen fluoride and a preparation method of hydrofluoric acid, and belongs to the technical field of preparation of hydrogen fluoride. The preparation method for hydrogen fluoride includes the following steps of: heating bifluoride solid to 150-450 DEG C so as to enable 10-40% of the bifluoride solid to be pre-decomposed and obtain paste; and then calcining the paste at 500-550 DEG C for decomposition so as to obtain fluoride and crude hydrogen fluoride gas, wherein the bifluoride is sodium bifluoride or potassium bifluoride. According to thepreparation method of hydrogen fluoride, incomplete decomposition caused by melting of the bifluoride can be reduced by heating the bifluoride solid for pre-decomposition and then performing high-temperature calcination, the rate of the decomposition reaction is accelerated, and the production efficiency is improved; meanwhile, by heating the bifluoride solid for pre-decomposition at a low temperature before high-temperature calcination, corrosion, which is caused by the hydrogen fluoride gas generated by the decomposition due to moisture or water absorption of the bifluoride solid, to equipment can be reduced when high-temperature calcination is performed.

The invention provides a preparation method of large-particle sodium bifluoride. The method comprises the following steps: (1) preparing a sodium carbonate solution dissolving sodium carbonate in water to obtain the sodium carbonate solution; (2) carrying out a synthesis reaction on the sodium bifluoride: adding an appropriate amount of sodium bifluoride seed crystals into a reactor, adding the sodium carbonate solution, obtained in the step (1), and hydrofluoric acid into the reactor at the same time while stirring, and continuously stirring for carrying out a reaction after the end of feeding so as to obtain suspension; (3) filtering: filtering the suspension obtained in the step (2) so as to obtain a sodium bifluoride filter cake; (4) drying: drying the sodium bifluoride filter cake obtained in the step (3) so as to obtain the large-particle sodium bifluoride product. The method provided by the invention solves the problems that the sodium bifluoride product prepared by the traditional preparation method is fine in particles, high in drying difficulty and poor in operating environment.

The invention relates to a method for producing cryolite, which takes electrolyte blocks of aluminum factories and sodium bifluoride as raw materials which are then reacted with each other in a solid phase. The method adopts a great deal of waste residue of the electrolytic aluminum factories - the electrolyte blocks as the raw materials, thereby the method increases a source of raw materials forproducing villiaumite, relieves the dependency on fluorite, saves a large number of valuable resources, has low cost, greatly reduces the production cost, and relieves the ambient environmental pollution problem. Moreover, products generated during the reaction process of the method can be recycled, thereby the method greatly reduces the production cost to a certain degree, has good social benefit and economic benefit, and is easy to promote and apply.

The invention provides a preparation process for racemic cis-8-benzyl-2,8-diazabicyclo[4,3,0]nonane, which comprises the following steps: Step S1: preparing an attachment carrier: immersing a solid carrier into Prepare an attachment carrier in a roughening solution, the roughening solution is a sodium hydroxide solution or a sodium bifluoride solution; Step S2: Prepare a platinum dehydrogenation catalyst: use an impregnation method to support the precious metal platinum by impregnating it into an impregnation solution containing noble metal ions On the solid carrier, in parts by weight, the impregnation solution includes 30-40 parts of chloroplatinic acid and 1-5 parts of rice furoic acid; step S3: piperidine ring dehydrogenation reaction; step S4: high-pressure hydrogenation reaction. The invention provides a method for preparing racemic cis-8-benzyl-2,8-diazabicyclo[4,3,0]nonane with high selectivity, high catalytic efficiency and high product purity.

A brazing material outer coat and a method for preparing the same, an in-situ synthetic metal-coated flux-cored silver brazing material and a method for preparing the same, a welding method and a joint body, wherein the in-situ synthetic metal-coated flux-cored silver brazing material comprises a flux core and a brazing material outer coat wrapping the flux core, the brazing material outer coat comprises, in percentage by weight: silver Ag 20.0˜36.0%, copper Cu 35.0˜45.0%, zinc Zn 27.0˜37.0%, tin Sn 1.0˜3.0%, phosphorus P 0.1%˜0.5%, nickel Ni 0.5˜2.0%, germanium Ge 0.1˜0.3%, and lithium Li 0.1˜0.3%, the flux core comprises, in percentage by weight: elemental boron micropowder 5.0˜10.0%, sodium borohydride 5.0˜10.0%, potassium fluoroborate 15.0˜30.0%, boric anhydride 25.0˜40.0%, sodium fluoride 10.0˜30.0%, sodium bifluoride 2.0˜4.0%, and copper sulfate 1.0˜5.0%. The in-situ synthetic metal-coated flux-cored silver brazing material in the present disclosure realizes self-reaction in a brazing process to coat a layer of copper film on a surface of a brazed metal, the core of the brazing material has good wettability, good flowability, self-brazing function, and zinc being hard to volatilize, the flux coat has high activity, low hygroscopicity, few carbon residues, good plasticity and toughness, etc. The present disclosure is particularly suitable for brazing pipeline components of stainless steel, manganese brass and so on.

The invention provides a cleaning method of an ultra-filtration membrane used in membrane-process polymer-flooding oilfield wastewater treatment. The cleaning method comprises the steps of (1) physical cleaning and chemical cleaning, wherein chemical cleaning comprises the following steps: (2) cleaning with a pickling solution; (3) cleaning with a sodium hydrogenfluoride and alkaline mixed solution, a sodium hydrogenfluoride and acid mixed solution or a sodium hydrogenfluoride and sodium fluoride mixed solution; (4) cleaning with an oxidizing agent lotion; (5) cleaning with a membrane cleaning additive; (6) cleaning with a surfactant or an organic solvent cleaning agent.

The invention discloses a Mn4+ doped sodium hydrogen fluoride red light material and a preparation method thereof. The chemical composition of the material is NaHF2:Mn4+, with 15-30mL HF (concentration: wt 40%), 1×10‐4~9×10‐4mol K2MnF6 solid, 0.01~0.1mol NaF as raw materials, adding deionized water to make The total volume is 40 mL, stirred and reacted at room temperature for 0.5-2 hours, filtered with suction, and dried naturally at room temperature to obtain a white powder. The product emits bright red light under ultraviolet light, and its largest excitation band completely matches the blue light spectrum emitted by the white LED blue chip. Its emission spectrum consists of four red light emission peaks at 595-643nm. The material may be applied to dichroic white LEDs to improve their color rendering index. The product does not contain rare earth, has a simple preparation method and is suitable for industrial production.

The invention relates to a method for producing cryolite, which takes carbon residue of aluminum factories and sodium bifluoride as raw materials which are then reacted with each other in a solid phase. The raw materials of the method adopt a great deal of waste residue - the carbon residue of the electrolytic aluminum factories, and the cryolite product is prepared after flotation treatment and particularly refining treatment of products. The method increases a source of raw materials for producing villiaumite, relieves the dependency on fluorite, saves a large number of valuable resources, has low cost, greatly reduces the production cost, and relieves the ambient environmental pollution problem. Moreover, carbon powder containing about 10 percent of electrolyte obtained after flotation of the carbon residue can be dried and then used as auxiliary materials to be added when bottom paste is manufactured, and used for building a novel groove. Products generated during the reaction process of the method can be recycled, thereby the method greatly reduces the production cost to a certain degree, has good social benefit and economic benefit, and is easy to promote and apply.

In order to solve the deficiencies in the prior art, the invention provides a method for preparing sodium bifluoride by using fluorosilicic acid, a by-product of phosphorus chemical industry, comprising: S1. reacting fluorosilicic acid, a by-product of phosphorus chemical industry, with ammonia water, and solidifying after the reaction is completed Liquid separation to obtain solid phase component A and liquid phase component A. S2. react the liquid phase component A with the slaked lime, and perform three-phase separation after the reaction to obtain the solid phase component B, the liquid phase component B and the gas phase component A. S3. React the solid phase component B with concentrated sulfuric acid, and perform three-phase separation after the reaction to obtain solid phase component C, liquid phase component C and gas phase component B. S4. React the gas phase component B with saturated sodium carbonate solution, and perform three-phase separation after the reaction to obtain solid phase component D, liquid phase component D and gas phase component C. S5. The solid phase component D is dried and pulverized in sequence to obtain the sodium bifluoride product. The invention can prepare fluosilicic acid into sodium hydrogen fluoride, which makes up for the vacancy in the prior art.