503 results about "Hydrogen fluoride" patented technology

The invention discloses an efficient thermal cycle drying device for producing flaky ammonium bifluoride, and relates to the technical field of ammonium bifluoride production. Comprising a machine body, an exhaust pipe and an air inlet sleeve, a first shell and a second shell are sequentially mounted at the upper end of the machine body from left to right, an air inlet cavity is formed in the bottom of the inner side of the machine body, and a mounting cylinder is connected to the upper end of the air inlet cavity through a spring; through cooperation of a mounting cylinder, a movable cylinder, a scraping plate and a first adjusting assembly, when materials are subjected to traditional one-way vibration blowing heat exchange, the materials are thrown and turned in the other direction to increase the drying uniformity, meanwhile, the air flow pressure of an exhaust hole is correspondingly adjusted, and the heat exchange drying effect is improved; and through cooperation of the movable barrel and the second adjusting assembly, when materials with the large water content and the large feeding amount are dried, the moving speed of the materials is increased, meanwhile, the air flow pressure of the exhaust holes is correspondingly adjusted, and the heat exchange drying effect is improved.

The invention relates to a method for recovering lithium and fluorine from aluminum electrolysis hazardous waste, which comprises the following steps: firstly, mixing organic polyol and alkaline hydroxide according to a molar ratio of 1: (0.5-2) to obtain a eutectic solvent; heating the eutectic solvent to 80-150 DEG C, and adding a proper amount of raw material fine powder and calcium oxide for reaction leaching; carbonating and filtering the leachate to obtain lithium carbonate; washing the leaching residues with an acetic acid solution to obtain a calcium fluoride product; the concentration of fluorine ions in the leachate is smaller than or equal to 200 ppm, and the purity of calcium fluoride is larger than or equal to 90%; the leaching rate of lithium in the method is greater than 85%; the slag feeding rate of fluorine is greater than 95%; and no hydrogen fluoride gas is generated in the method. According to the method, a non-toxic and biodegradable eutectic solvent is adopted as a leaching agent, and efficient leaching of lithium and fluorine in the aluminum electrolysis dangerous waste materials is achieved; calcium oxide is used as a precipitating agent, free fluorine is promoted to be precipitated and recycled as calcium fluoride, the whole process meets the requirement of green metallurgy, and the win-win situation of resources and the environment is achieved.

The invention discloses a simulated screening and process optimization method of an anhydrous hydrogen fluoride desulfurization adsorbent, and relates to the technical field of anhydrous hydrogen fluoride, and the method comprises the following steps: constructing a database, and establishing a basic screening library; constructing an intelligent screening engine, and performing force field parameter correction on the materials in the basic screening library to capture a high-polarity solvent effect; calculating and extracting adsorption selectivity, Henry coefficients and working capacity indexes, and screening out a primary candidate material set; a core candidate material is optimized; determining an optimal adsorbent model; the microscopic adsorption data of the optimal adsorbent model are converted into macroscopic process parameters, the macroscopic process parameters are imported into a macroscopic process simulator for prediction, and process optimization is completed. According to the method, the strong polar solvent effect is simulated by constructing the corrected force field environment, and high-throughput screening of the adsorption materials is achieved in combination with an active learning strategy; an electronic grade refinement and modification strategy is utilized to optimize adsorption sites, and microcosmic adsorption data and a macroscopic mass transfer model are coupled to realize accurate prediction and optimization of an adsorption process.

The invention relates to the technical field of hydrogen fluoride adsorption, and particularly discloses a hydrogen fluoride adsorption tower which comprises a tower body, a gas inlet pipeline arranged on the lower section of the tower body, a gas outlet pipeline arranged on the upper section of the tower body, a plurality of layers of adsorption beds arranged in the tower body in the vertical direction, and adsorbents arranged on the adsorption beds. The material changing mechanism comprises a waste material pipe rotationally arranged in the tower body, a driving part I for driving the waste material pipe to rotate, a plurality of inverted conical funnels respectively arranged below the plurality of layers of adsorption beds and a plurality of trapping boxes arranged on the waste material pipe, and the waste material pipe penetrates through all the adsorption beds; a plurality of spiral scrapers for driving the adsorbent to radially flow are arranged on the waste pipe, the upper end of the inverted-cone-shaped funnel exceeds the outer edge of the adsorption bed, an annular air jet hole is formed in an outlet in the bottom of the inverted-cone-shaped funnel, and the trapping boxes surround the waste pipe in an annular array; the device has the beneficial effects that saturated aluminum oxide is separated in time, so that the adsorption effect of the aluminum oxide is improved.

Provided is a method that allows for the etching of a silicon nitride film with respect to a silicon oxide film with high selectivity and high precision while preventing a degradation in the shape of the silicon oxide film portion during etching. The etching method of dry etching a film structure which is formed in advance on a wafer disposed in a processing chamber and in which an end portion of a film stack including a silicon nitride film and silicon oxide films vertically sandwiching the silicon nitride film forms a sidewall of a trench or hole, by supplying a gas for processing into the processing chamber, without using plasma includes: forming, as a first process, a reaction layer on the silicon nitride film by reaction of hydrogen fluoride gas at 30° C. or higher and 55° C. or lower; removing, thereafter, as a second process, the reaction layer having been formed in the first process, through volatilization by performing heating at 70° C. or higher and 110° C. or lower without causing the hydrogen fluoride gas to flow; and etching the silicon nitride film from the end portion in a lateral direction by performing the first and second processes a plurality of times.

An oxide film etching method includes: forming a protective film of a metal or a metal nitride that does not contain silicon so as to cover a protection target film, among the protection target film containing silicon and a silicon-containing oxide film exposed on a surface of a substrate; supplying, to the substrate, a mixed gas including a hydrogen fluoride gas and an ammonia gas to react with the silicon-containing oxide film, and modifying the oxide film to generate a reaction product; and sublimating and removing the reaction product.

The present application relates to a kind of methods for preparing ultra-high purity quartz sand by deep purification, belong to high-purity quartz high-efficiency preparation and non-metallic mineral fine and deep processing technical field.The method is placed in supercritical reaction device with quartz sand raw material, and mixed fluid of composite entraining agent and supercritical carbon dioxide is introduced into the device to carry out reaction, after separation, washing and drying, high-purity quartz sand product is obtained;The composite entraining agent is the combination of acid medium and metal complexing agent;The volume fraction of the acid medium in the mixed fluid is 0.5%~5%, and the acid medium is hydrogen fluoride and / or hydrogen chloride.The method has the advantages of simple process flow, high purification efficiency, controllable purification degree and stable product performance.

The etching method disclosed herein includes a process (a) of preparing a substrate within a chamber of a plasma processing apparatus. The substrate includes a silicon-containing film. The etching method also includes a process (b) of etching the silicon-containing film by chemical species from a plasma formed from a process gas within the chamber. The process gas includes a phosphorous-containing gas, a fluorine-containing gas, and a hydrogen-containing gas. The hydrogen-containing gas contains at least one selected from the group consisting of hydrogen fluoride, H2, ammonia, and a hydrocarbon.

The invention provides a nitrogen-fluorine double-element doped porous carbon material, a silicon-carbon negative electrode material and a preparation method thereof, and the preparation method of the porous carbon material comprises the following steps: mixing porous carbon with ammonium fluoride and / or ammonium bifluoride, and carrying out vapor deposition coating or liquid phase coating; and calcining the coated porous carbon material in a closed environment in an inert atmosphere to obtain the nitrogen-fluorine double-element doped porous carbon material. According to the invention, by utilizing the characteristics of nano-scale micropores and super-large specific surface of porous carbon and the properties of low melting point and low boiling point of ammonium fluoride and ammonium bifluoride, a uniformly coated ammonium fluoride and ammonium bifluoride coating layer is obtained by adopting a vapor deposition or liquid phase coating method, and then the porous carbon material is obtained by utilizing high-temperature calcination treatment. According to the present invention, the characteristics of high specific surface and nano-scale micropores can be simultaneously retained, and after the silicon-carbon negative electrode material is prepared, the expansion of the silicon-carbon negative electrode material is substantially reduced, the cycle performance of the material is ensured, and the rate capability of the obtained silicon-carbon negative electrode material is improved.

The utility model relates to the technical field of anhydrous ammonium hydrogen fluoride preparation, and discloses a micro-channel reaction device for preparing anhydrous ammonium hydrogen fluoride, which comprises a raw material tank, a vaporizer, a micro-channel reactor and a shell-and-tube heat exchanger, two driving motors are mounted at the upper end of the micro-channel reactor, stirring rods are mounted at the lower ends of the driving motors through motor shafts, a plurality of stirring blades are arranged on the stirring rods, a micro-channel groove is formed in the middle in the micro-channel reactor, a plurality of channels are uniformly distributed in the micro-channel groove, and two catalysts are mounted at the bottom end in the micro-channel reactor. Two driving motors are started, the driving motors drive stirring rods to rotate through motor shafts, the flow speed of ammonium bifluoride gas is increased, multiple channels are formed in the micro-channel groove, the contact area and the retention time of reaction gas can be increased through the channels, the reaction efficiency is improved, the reaction gas reacts with other reactants under the action of a catalyst, and the reaction efficiency is improved. Anhydrous ammonium bifluoride and other byproducts are generated, so that the reaction is sufficient.

The invention relates to an improved process for the manufacture of a fluorinated organic compound, wherein the process comprises a fluorination reaction of an organic precursor compound having at least one chlorine substituent and / or at least one double bond, and said organic precursor compound is reacted in liquid phase in HF (hydrogen fluoride) serving as solvent and fluorinating agent in the presence of a fluorinating catalyst, and wherein the fluorination reaction is performed in liquid phase in a SiC block chemical reactor, and wherein the reaction mixture is withdrawn from SiC block chemical reactor, and wherein the process comprises optionally isolating and / or purifying the targeted fluorinated organic compound.

The production of HFO-1132, and in particular HFO-1132 E, may be produced from 1, 1, 2-trichloro-1, 2, 2-trifluoroethane (CFC-113), and the production of HFO-1132, and in particular HFO-1132 E, may be produced from 1, 1, 2-trichloro-1, 2, 2- In a first step, 1, 1, 2-trifluoroethane (HFC-143) is produced by hydrogenating 1, 1, 2-trichloro-1, 2, 2-trifluoroethane (CFC-113) by reacting with hydrogen in the presence of a catalyst to produce 1, 1, 2-trifluoroethane (HFC-143). The 1, 1, 2-trifluoroethane (HFC-143) may then be dehydrofluorinated in the presence of a catalyst to produce trans-1, 2-difluoroethylene (HFO-1132E) and / or cis-1, 2-difluoroethylene (HFO-1132Z). The cis-1, 2-difluoroethylene (HFO-1132Z) may then be isomerized to produce the trans-1, 2-difluoroethylene (HFO-1132E), and then the cis-1, 2-difluoroethylene (HFO-1132Z) may be isomerized to produce the cis-1, 2

The invention discloses a method for producing anhydrous hydrofluoric acid from photovoltaic fluorine-containing waste materials. The waste materials are fluorine-containing solid press filter residues or filter cake biscuits obtained through solid-liquid separation after photovoltaic fluorine-containing waste liquid treatment. The method comprises the following steps: drying, crushing and screening the waste until the waste is matched with the fluorite powder in particle size, returning the oversize product to the crushing, closed-loop granulating and homogenizing; continuously metering and uniformly mixing the homogenized waste and fluorite powder according to a mass ratio of 20: 1 to obtain a mixed fluorine-containing raw material, and continuously feeding the mixed fluorine-containing raw material into a rotary reaction furnace; fuming sulfuric acid and concentrated sulfuric acid are mixed into mixed acid, the mixed acid is continuously added into a reaction furnace, the mixed acid reacts at the temperature of 300-350 DEG C to generate a fluorine-containing gas phase, and reaction heat is indirectly provided by circulation of high-temperature gas in a jacket of the reaction furnace; the crude product gas enters a degassing tower to remove SO2 and SiF4 after being subjected to dust removal, washing, cooling, condensation, rectification, deacidification and dehydration, and an anhydrous hydrofluoric acid product is obtained. According to the method, waste recycling is achieved, and fluorite consumption and waste disposal amount are reduced.

The application discloses a continuous production process and equipment for a trifluoromethylbenzene tower, and belongs to the field of organic fluorine chemistry. The production process comprises the following steps: S1: continuously feeding trichloromethylbenzene and hydrogen fluoride into a tower reactor connected with a heat exchanger circulating cooling system in a reverse direction, so that a three-stage continuous fluorination reaction occurs in the tower reactor to obtain crude trifluoromethylbenzene, and unreacted hydrogen fluoride is separated into liquid at the top of the tower and then flows back into the tower reactor; S2: the crude trifluoromethylbenzene obtained in the reaction is subjected to nitrogen bubbling in a bubble tower, and then is continuously distilled in a rectifying tower to obtain finished trifluoromethylbenzene; and S3: byproduct hydrogen chloride generated in the fluorination reaction is introduced into a hydrochloric acid tank to obtain hydrochloric acid, and the content of hydrofluoric acid in the hydrochloric acid is less than 1000 ppm. The method can greatly improve the utilization rate of raw material hydrogen fluoride, improve the purity of byproduct hydrochloric acid, reduce the generation amount of waste acid, avoid the sharp change of pressure in the reaction process, and realize large-scale, continuous, stable and safe production of trifluoromethylbenzene.

The present invention relates to an etching solution for an active metal solder, which is used to etch an active metal solder layer containing Ag, Cu, and an active metal, and which contains ammonium fluoride, borohydrofluoride acid, and one or two elements selected from the group consisting of hydrogen peroxide and ammonium peroxydisulfate.

The invention relates to an environment-friendly process method for improving the surface metal cleaning efficiency of a silicon wafer, and belongs to the technical field of semiconductor silicon wafer processing, and the process method comprises the following operation steps: S1, pre-cleaning and activation: placing the silicon wafer in a first cleaning tank, introducing ozone into ultrapure water, and processing in cooperation with low-frequency ultrasound; and S2, main cleaning and complexing: placing the silicon wafer subjected to pre-cleaning and activating treatment in a second cleaning tank, and treating the silicon wafer in a dilute citric acid solution in cooperation with high-frequency ultrasound. And S3, overflow rinsing: placing the silicon wafer subjected to main cleaning and complexing treatment in a third cleaning tank. And S4, drying: carrying out drying treatment on the silicon wafer subjected to the overflow rinsing treatment. Through the synergistic effect of physical stripping, chemical oxidation and complexing dissolution, under the condition that highly toxic chemicals such as hydrofluoric acid are not used, the cleanliness of metal on the surface of the silicon wafer reaches the ppt level, and the problems that traditional RCA cleaning is serious in environmental pollution and high in operation risk are effectively solved.

The invention provides novel azeotrope-like compositions and separation processes utilizing the same. An azeotrope-like composition comprising 1,2-difluoroethylene (HFO-1132) and hydrogen fluoride. An azeotrope-like composition comprising 1,1,2-trifluoroethylene (HFO-1123) and hydrogen fluoride. A separation process for a composition comprising at least one member selected from the group consisting of trans-1,2-difluoroethylene (HFO-1132(E)), cis-1,2-difluoroethylene (HFO-1132(Z)), and 1,1,2-trifluoroethylene (HFO-1123) and hydrogen fluoride.

This disclosure includes the following steps: (a) forming an oxide SiGe film on the first side and an oxide Si film on the second side by oxidizing a first side of the SiGe layer and a second side of the Si layer respectively using a gas containing free radicalized oxygen; and (b) selectively etching the oxide SiGe film using hydrogen fluoride or a mixture of hydrogen fluoride and an inactive gas while maintaining the temperature of the semiconductor substrate above TL (°C) and below TH (°C). When the atomic ratio of Ge to Si in the SiGe layer is set to C (%) and the pressure or partial pressure of hydrogen fluoride in step (b) is set to P (Pa), C (%) < 25%, 50Pa ≤ P (Pa) ≤ 1000Pa, TL = 11.3 × LN (P) + 0.23 × C - 97.4, TH = 13 × LN (P) + C - 102.

The invention belongs to the technical field of infrared focal plane sensor manufacturing, and particularly relates to a vanadium oxide etching post-processing method based on VHF wetting driving. Comprising the following steps: performing graded vacuumizing and temperature programming pretreatment on a wafer subjected to vanadium oxide etching, and continuously introducing VHF moistening mixed gas consisting of anhydrous hydrogen fluoride, ethanol steam and inert carrier gas into a treatment cavity; by accurately regulating and controlling the temperature and pressure of the cavity, anhydrous hydrogen fluoride is promoted to be subjected to a selective fluorination reaction with photoresist decomposition products and metal impurities left after etching to generate gaseous products, and ethanol steam synchronously exerts the dual effects of moistening, corrosion prevention and water molecule desorption promotion. According to the method, a gas phase processing mode is adopted in the whole process, liquid intervention is avoided, the problems of vanadium oxide pixel adhesion and film corrosion can be effectively solved, meanwhile, residual impurities are thoroughly removed, the electrical property stability of the vanadium oxide film is guaranteed, the yield and detection precision of the infrared focal plane sensor are remarkably improved, and the method has good industrial application prospects.

We provide technology to improve the etching shape. [Solution] The disclosed etching method includes (a) providing a substrate having a base film, a silicon-containing film on the base film, and a mask on the silicon-containing film into a chamber; (b) etching the silicon-containing film to form recesses using a first plasma generated from a first processing gas containing hydrogen fluoride gas and tungsten-containing gas; and (c) after step (b), further etching the silicon-containing film using a second plasma generated from a second processing gas containing hydrogen fluoride gas, wherein the second processing gas does not contain tungsten-containing gas, or contains tungsten-containing gas at a flow rate less than that of the tungsten-containing gas in the first processing gas.

The utility model discloses a kind of hydrogen fluoride acid-resistant storage tanks, including upper head, barrel and lower head sequentially arranged from top to bottom, upper head, barrel and lower head are cut after by hydrogen fluoride acid-resistant composite material, and assembled into storage tank.The hydrogen fluoride acid-resistant composite material sequentially includes inner lining layer, anti-permeation layer, strength layer, outer protective layer and anti-aging layer from inside to outside, and adjacent layer and layer are bonded fixed.In inner lining layer, anti-permeation layer of structure layer inside, reinforcing fiber is polyester fiber, in outer protective layer of structure layer outside, reinforcing fiber is also polyester fiber, polyester fiber can resist HF corrosion, structure layer is arranged between anti-permeation layer and outer protective layer, and glass fiber reinforced material cannot be subjected to medium corrosion by using.The storage tank structure of the utility model guarantees the corrosion resistance of storage tank while guaranteeing the strength of tank body.

To provide a new method for producing a fluorinated organic compound in which removal or separation of an auxiliary is easy and which is advantageous in production cost.SOLUTION: A compound represented by the following formula (1): wherein R1, R2 and n are as defined in the description. The method comprises reacting the compound represented by the formula (1) with (A) at least one fluorine source selected from hydrogen fluoride, a hydrogen fluoride salt and a fluoride salt, (B) at least one iodine source selected from iodine and ammonium iodide, and (C) a compound having at least one fluorinated quaternary nitrogen atom in the molecule. A step of difluorinating the compound represented by the formula (1), wherein the amount of the iodine source (B) used is less than 1.0 mol per 1 mol of the compound represented by the formula (1).SELECTED DRAWING: None

The present invention provides a method and apparatus for etching a semiconductor substrate to remove a target material from the substrate surface. [Solution] A thermal technology that does not rely on the use of plasma, the method involves supplying a specific gas mixture to a reaction chamber and reacting it with a target material. The gas mixture may include a mixture of a halogen source such as hydrogen fluoride (HF), an organic solvent and / or water, an additive, and a carrier gas. Multiple different materials may be used for the organic solvent and / or the additive.

The utility model relates to a kind of rectifying column of low-grade fluorite preparation anhydrous hydrogen fluoride.The rectifying column of low-grade fluorite preparation anhydrous hydrogen fluoride includes tower body, tower body is equipped with tray, tray includes plate body, plate body upper side is equipped with overflow plate, plate body between two overflow plates is equipped with steam passage, plate body is equipped with downcomer, steam passage is equipped with steam pipe, plate body upper side is equipped with cover cap covering steam pipe upper side, cover cap is equipped with steam outlet, the inboard of cover cap is equipped with adjusting ring, plate body is equipped with the guide rod moving up and down, the upper end of guide rod is fixedly connected with adjusting ring, the lower end of guide rod extends plate body lower side and is fixedly connected with push plate, and reset spring is equipped between guide rod and plate body lower side face.The utility model can increase the steam area of steam outlet when steam pressure rises, thereby relieving steam pressure rise, avoid the evaporation temperature rise caused by steam pressure rise, and increase the indirect contact between steam and hydrofluoric acid, improve rectification efficiency.

The utility model relates to hydrogen fluoride production technical field discloses a pipeline descaling system for hydrogen fluoride production, include: evaporative cooling device has the accommodation cavity, fills with domestic water in the accommodation cavity, the cooling pipe inside fills with freon, first pipeline sets up the outside of evaporative cooling device, the import of first pipeline communicates with the below outside end surface of evaporative cooling device, and the export of first pipeline communicates with the outside end surface of the above of evaporative cooling device, first pipeline circulates domestic water through the drive part, and the parallelly connected setting of permanent magnet descaling device is in first pipeline, the utility model discloses through setting permanent magnet descaling device, utilizes the magnetic field effect, changes the scale layer crystallization form, makes it difficult to adhere to the pipe wall, the freon in cooling pipe can more efficiently carry out the cooling at this moment, and the heat exchange effect is high.

The present application relates to a method for reducing the content of sulfur in aluminum fluoride, which comprises the following steps: uniformly mixing crude aluminum fluoride powder containing sulfate impurities with ammonium hydrogen fluoride powder to obtain a mixture; placing the mixture in a reactor and performing programmed temperature calcination under a protective atmosphere; discharging the sulfur and fluorine-containing volatile gas generated by calcination after treatment by an absorption system; cooling the calcined material to room temperature; washing the cooled material with water or blowing inert gas to remove residual ammonium salt or dust, and then drying to obtain a low-sulfur aluminum fluoride product. The in-situ HF generated by the decomposition of NH4HF2 is used for gas-solid reaction, which can effectively attack and convert stable sulfate impurities existing in various forms, has high desulfurization efficiency and is deep and thorough; the reaction conditions are mild, the main phase of the product is stable, the process flow is simple, and the energy consumption is low.

This invention discloses a method for treating ammonium fluorosulfate byproducts, comprising providing an ammonium fluorosulfate byproduct mainly comprising ammonium fluorosulfate and a small amount of fluorosulfonic acid and bis(fluorosulfonyl)imide; mixing the ammonium fluorosulfate byproducts with water; reacting the mixture of ammonium fluorosulfate byproducts and water at a hydrolysis reaction temperature to hydrolyze the ammonium fluorosulfate, fluorosulfonic acid and bis(fluorosulfonyl)imide to form an aqueous solution of ammonium bisulfate and hydrogen fluoride; and separating the ammonium bisulfate from the aqueous solution of hydrogen fluoride.

The present application relates to a kind of porous gel electrolyte membrane based on polyvinylidene fluoride and its preparation method, belong to polymer gel electrolyte field.The porous gel electrolyte membrane includes gel electrolyte matrix, inorganic ceramic nano filler, lithium salt electrolyte and lithium salt auxiliary agent.Using phase inversion solidification method, the uniform porous structure is obtained, the adsorption and storage capacity of porous gel electrolyte membrane to electrolyte are improved;Using inorganic ceramic nano filler with high ionic conductance, the ionic conductance and mechanical strength of porous gel electrolyte membrane are enhanced;Using lithium salt added during preparation, the dehydrofluorination reaction of PVdF is inhibited, the stability of slurry is ensured, and by inducing the transition of PVdF matrix from alpha phase to beta phase, the uniform deposition of Li ion is promoted, so as to improve the cycle stability of battery.The preparation method of the present application is simple, easy to control, green and environmentally friendly, can significantly improve the ion transport kinetics and electrochemical stability of lithium ion battery.

The invention provides a high-temperature-resistant anti-oxidation prebaked anode coating material. The coating material is prepared from the following materials in percentage by mass: 65%-68% of an aluminum oxide base material, 5% of a grain pre-activation material, 0.4%-0.6% of a nano yttrium oxide material, 21%-23% of a modified silica sol material and the balance of water, the invention further provides a preparation method of the high-temperature-resistant antioxidant prebaked anode coating material, the method is simple in process and controllable in cost, and the prepared coating material is convenient to use and suitable for large-scale popularization. The high-temperature-resistant anti-oxidation prebaked anode coating material prepared by the invention can be sintered at a low temperature, a protective layer is formed on the surface of an anode, and corrosion of oxygen, hydrogen fluoride gas, carbon dioxide gas and cryolite steam to an anode carbon block at a high temperature is prevented, so that the problems of high-temperature oxidation consumption of the prebaked anode in the service process and impurities brought in molten aluminum are solved.