79results about How to "Low content of metal impurities" patented technology

The invention provides a method for preparing mesoporous asphaltic base globular active carbon by dipping metal salt and secondary carbonization. The method comprises the steps of dipping and mixing the mipor asphaltic base globular active carbon prepared by the traditional method with an inorganic metal salt solution by a certain ration; heating under an inert atmosphere to 600-1200 DEG C at a temperature increasing rate of 1 to 20 DEG C/min for the secondary carbonization; using acid to wash off the remaining metal inside the carbonized material, so as to obtain asphaltic base globular active carbon with high mesoporous rate and narrow distribution of mesoporous spertures.

The invention belongs to the technical fields of a novel material as well as preparation, and particularly relates to mesoporous graphene foam as well as a preparation method thereof. The invention realizes hydrothermal preparation of a magnesium oxide texture structure and preparation of the mesoporous graphene foam by using textured magnesium oxide as a template. The mesoporous graphene foam material has abundant mesoporous structures and excellent electric property and can be used as an electrode material of batteries and supercapacitors, so that the energy density and the power density of the batteries or the supercapacitors are expectedly improved to a great extent. The cycling stability of the mesoporous graphene foam material is increased, and the mesoporous graphene foam material combined with materials with high draw ratio or the mesoporous graphene foam material can soften energy storage apparatuses. The advantages have important meaning for realization of commercialization of a new generation of energy storage apparatuses for electromobiles and development of smaller, lighter and flexible portable mobile power supplies. The business prospect is wide. Meanwhile, preparation processes of the high temperature hydrothermal method and a fluidized bed can realize engineering enlargement, so that the method is expected to be industrialized.

The invention discloses a method for removing metal impurities from carbon nano tubes. The method includes following steps: (1) preparing a carbon nano tube acid solution from the carbon nano tubes with an inoxidizing acid solution; (2) mixing and stirring the carbon nano tube acid solution uniformly and grinding the carbon nano tube acid solution in a grinder; (3) stirring the grinded carbon nano tube acid solution in a stirring kettle, taking out the grinded carbon nano tube acid solution and removing waste solution with a filter press to prepare a carbon nano tube filter cake; (4) feeding the carbon nano tube filter cake in the stirring kettle, adding deinoized water with stirring for cleaning metal ions in the solution until a filtrate is neutral; and (5) drying and crushihng the carbon nano tube filter cake to obtain high-purity carbon nano tubes. The method is characterized in that original lengths and structures of the purified carbon nano tubes are retained and the carbon nano tubes is excellent in electric-conductive performance. By means of the method, the content of metal impurities in the carbon nano tubes can be reduced from 20% to less than 2%. The method is high in efficiency, is simple in operations and can achieve industrialized production.

The invention relates to the technical field of metallurgical polysilicon purification, in particular to a hydrometallurgical purification method. The purification method of the present invention is as follows: the silicon powder with a particle size of 100 to 200 meshes is subjected to magnetic separation by a magnetic separator for use, and is prepared by pre-cleaning, pickling with dilute hydrochloric acid, pickling with dilute hydrofluoric acid, pickling with aqua regia, and dilute hydrofluoric acid. Acid and hydrogen peroxide pickling process pickling, the solid-to-liquid ratio is 1:3, soak for 12-16 hours, stir for 15 minutes every hour during soaking, and then rinse with deionized water for many times until the pH value of the water For neutrality, centrifugal drying, drying, packaging. Using the purification method of the present invention, by optimizing the conditions such as silicon powder particles, acid concentration, soaking time and stirring, the total content of metal impurities in metallurgical polysilicon is reduced to 100ppmw in advance, and the effect of 4N purity metallurgical silicon can be obtained, and reach A simple, easy, low-cost method that can be mass-produced.

The invention relates to a preparation method of a semiconductor wafer cutting blade material. In the preparation method, high-purity green silicon carbide and black silicon carbide are adopted as raw materials, and a wafer cutting blade material is prepared through the steps of jaw crushing and sifting, wet ball milling classification, pickling, overflow size separation, concentrating and dewatering, drying, blending, fine screening and the like. Silicon carbide blade materials prepared through the method are most in equiareal shape and keep sharp edges and strong cutting power, can minimize TTV of a silicon wafer, and have strong adaptability to cutting fluid such as polyethylene glycol and the like because blade material particles have larger specific area and clean surfaces. Products crushed by a wet ball mill are most in equiareal shape, have high output, and can avoid excessive crushing. The preparation method of the invention can reach over 50% of rate of finished products, and products milled with the technology have more uniform size and distribution of particles, thereby better cutting effect to silicon wafers can be achieved.

The invention discloses a method for dealkalizing aluminum-reinforced red mud and separating and recovering aluminum and iron, which comprises the following steps: dissolving red mud in water, introducing excessive SO2, introducing oxygen for aeration at the same time, and enabling a part of filtered alkaline leachate to flow back; when the pH value of a red mud mixed solution is reduced to 3 or below, conducting washing and filtering on the red mud mixed solution, then adding NaOH into an acidic leachate to adjust the pH value to strong alkalinity, conducting aging and filtering on a leachateagain, treating filter residues, recovering Fe2O3, and meanwhile, enabling the filtered alkaline leachate to flow back to the red mud mixed solution; and adjusting the pH value of the residual filtered alkaline leachate to be weakly acidic, and then conducting filtering to recover aluminum. According to the method, SO2 is introduced into the red mud mixed solution for acidification and desulfurization, a part of filtered alkaline leachate containing Al<3+> flows back to the red mud mixed solution, and thus dealkalization of the red mud is reinforced; and filter residues obtained by filteringthe alkaline leachate are subjected to the steps of drying, sintering and the like, and almost pure Fe2O3 can be obtained; and the pH value of the residual filtered alkaline leachate is adjusted to beweakly acidic, and Al(OH)3 can be recovered through filtering.

The invention provides a method for preparing silicon tetrachloride for optical fiber. The method comprises the following steps of: introducing chloride under the protective atmosphere of inactive gas or inert gas and under the condition of illumination, so that trichlorosilane is subjected to a photochemical reaction in a rectifying tower, wherein high-boiling-point silicon tetrachloride generated in the production process of polycrystalline silicon serves as a raw material; and controlling the tower kettle temperature and the tower top temperature and taking materials by selecting proper reflux ratio to obtain an intermediate product; further rectifying and purifying the intermediate product to obtain high-purity silicon tetrachloride, wherein infrared transmissivity of hydrogen-containing impurities meets the requirement of the silicon tetrachloride for the optical fiber on impurity transmissivity; and the metal ion content meets the metal content standard of the silicon tetrachloride for the optical fiber. The method has the advantages that: the trichlorosilane with the boiling point close to that of the silicon tetrachloride is removed effectively; the hydrogen-containing impurity content and the metal impurity content of the silicon tetrachloride are reduced; the quality of the silicon tetrachloride purified and prepared by the process completely meets the requirement of optical fiber products; the reaction condition and the completeness are easy to control; other impurities are not introduced; and the method is implemented in an industrial scale and in an effective and economic mode.

The present invention discloses a low-ash and high-density polyethylene resin and a preparation method thereof, wherein the weight average relative molecular mass of the low-ash and high-density polyethylene resin is 3.0*10<5>-9.0*10<5>, the relative molecular mass distribution is 5-9, the density is 0.940-0.965 g/cm<3>, and the ash content is less than 100 ppm. According to the present invention, the low-ash and high-density polyethylene resin has advantages of uniform composition, low ash, low metal impurity content, and the like; with the three-reaction kettle series connection method, the relative molecular mass, the relative molecular mass distribution and the co-polymerization monomer distribution of the polymerization product are easy to adjust, and the method can be directly used for molding of the wet lithium-ion battery separation membrane; and the molded microporous separation membrane has characteristics of uniform pore size distribution, less pinholes, less fisheye, high yield, high tensile strength, and high puncture strength.

The present invention relates to a method for preparing silicon nitride by using recovery purification silicon wafer sawdust powder. The method is characterized by comprising the following steps: 1) adding silicon wafer sawdust powder to a container, introducing a protection gas, carrying out first heating under the protection of the protection gas, and carrying out a first thermal insulation treatment to obtain a powder A; 2) carrying out second heating on the powder A under the protection of the protection gas, carrying out a second thermal insulation treatment, and cooling to a room temperature to obtain a powder B, wherein the powder A is maintained to continuously rotate during the thermal insulation process; and 3) carrying out third heating on the powder B under the protection of the protection gas, carrying out a third thermal insulation treatment, and cooling to a room temperature to obtain the silicon nitride. With the method of the present invention, reasonable recovery utilization of a large amount of silicon wafer sawdust produced by photovoltaic industry can be achieved so as to reduce solar photovoltaic power generation cost.

The invention relates to a chemical deposition method of high-purity low-hydroxyl high-uniformity quartz glass, which comprises the following steps: (1) depositing a silicon source in a deposition cavity by adopting a vapor phase axial deposition method to obtain a low-density SiO2 loose body; wherein in the deposition process, the interior of the deposition cavity is controlled to be in a negative pressure environment, and the temperature is not higher than 500 DEG C; (2) in a closed environment filled with dehydroxylation airflow and oxygen, heating the low-density SiO2 loose body to 1100-1300 DEG C, so that the low-density SiO2 loose body is dehydrated, dehydroxylated and densified; then, placing the low-density SiO2 loose body in an inert gas environment, heating to 1470-1600 DEG C, and vitrifying the low-density SiO2 loose body to form transparent quartz glass; and (3) annealing the transparent quartz glass to obtain the high-purity low-hydroxyl high-uniformity quartz glass. The invention further discloses a device adopting the chemical deposition process. According to the chemical deposition method of the high-purity low-hydroxyl high-uniformity quartz glass, the production process is high in continuity, and the content of metal impurities in the produced quartz glass is extremely low.

The invention relates to a saggar used for graphene preparation. A material of the saggar is high-density graphite, the saggar comprises a saggar main body and a saggar cover, the top of the saggar main body is opened, the top of the saggar main body is covered by the saggar cover, wherein, the saggar main body comprises an external saggar wall body and an external cavity formed by the external saggar wall body, a gap is arranged on the external saggar wall body, so that the external cavity is communicated with the outside part; an internal saggar is arranged in the saggar main body, the internal comprises an internal saggar wall body and an internal cavity formed by the internal saggar wall body, and the external cavity is communicated with the internal cavity. The invention also provides a method for preparing a graphene material by using the saggar and the graphene material.

The invention relates to a purification process of octamethylcyclotetrasiloxane. The purification process comprises the following steps: by using high-purity argon as a carrier gas, removing metal impurities in octamethylcyclotetrasiloxane by an adsorption reaction in a slight boiling state; carrying out rectification purification, separating octamethylcyclotetrasiloxane from the adsorbent, and removing organic impurities, water and oxygen to obtain an octamethylcyclotetrasiloxane intermediate product; and conducting secondary rectification to further purify an octamethylcyclotetrasiloxane intermediate product so as to obtain a pure octamethylcyclotetrasiloxane product with purity of greater than 99.999%. The pure octamethylcyclotetrasiloxane product meets the cladding deposition requirement of an optical fiber preform.

The invention discloses environment-friendly cured carbon felt and a preparation method thereof. The cured carbon felt is prepared by taking natural bamboo fiber as the raw material. The preparation method of the cured carbon felt comprises the steps of cutting and degumming, pickling and silk making, acid treatment and softening, loosening and felting, carbonization and finalization, CVD treatment and high temperature treatment. Compared with an existing cured carbon felt preparation method, the preparation method of the cured carbon felt is environmentally friendly, the raw materials are rich in source, and the price is low. The monofilament diameter of the cured carbon felt is 10-15 micrometer; the cured carbon felt is mainly carbon, and the carbon content is 95-97%; the cured carbon felt can tolerate the temperature of 2,500 DEG C to the maximum, and the metal impurity content is less than 295ppm.

The invention discloses a method for preparing high-purity manganese sulfate from alabandite and a product prepared according to the method. The method comprises the following steps: I, calcining a raw material, and performing sulfuric acid leaching; II, performing decontamination; and III, performing purification, thereby obtaining the high-purity manganese sulfate. The method is simple in process, easy to operate, free of secondary environment pollution since a great amount of additive chemical reagents are not used in the preparation process, low in production cost and easy in on-scale industrial production; and the problem of heavy metal separation can be solved, the contents of heavy metal impurities of common manganese sulfate products can be remarkably reduced, and manganese sulfatewith very low metal impurities can be prepared.

A process for preparing white carbon black and sodium hexametaphosphate incldues such steps as neutralizing reaction between phosphoric acid and water glass to obtain white carbon black, filtering the resultant liquid, regulating pH value, evaporating, polymerizing reaction, cooling by roller pair, breaking and sieving to obtain finished sodium hexametaphosphate.

The invention discloses a deposition reaction device for manufacturing a low-loss optical fiber preform rod and a pressure adjusting method, and relates to the technical field of manufacturing of optical fiber preform rods. The device comprises a pressure gauge, a controller and a reaction vessel with an open top, wherein the pressure gauge and the reaction vessel are connected, and high-purity inert gas with purity higher than 99 percent circulates in the reaction vessel; a first blast burner for making a cladding layer and a second blast burner for making a core layer are arranged on one side of the reaction vessel, and the second blast burner is located between the first blast burner and a plane of the bottom of the reaction vessel; the bottom of the reaction vessel is connected with a matching pipe, the matching pipe is communicated with the inside of the reaction vessel, a flow adjuster is arranged on the matching pipe and the flow adjuster is connected with the pressure gauge through the controller. According to the deposition reaction device for manufacturing the low-loss optical fiber preform rod and the pressure adjusting method, metal impurities can be effectively prevented from entering glass micro-particle sedimentary bodies, the content of metal impurities in the manufactured optical fiber preform rod is low and the impurity absorption loss is smaller.