519 results about "Metallic impurities" patented technology

The invention relates to the technical field of engineering, in particular to a geomembrane defect detection system and method under the earth and stone medium coverage condition, and the geomembrane defect detection system comprises a multi-mode adaptive sensing module, an edge calculation module, a data fusion module, a digital twinning module and a decision and application module; compared with the defects that single resistivity or geological radar detection is adopted in the prior art, interference of medium conductivity and metal impurities is likely to happen, and the deep resolution is insufficient, the scheme adopts multi-mode sensor network cooperative work, and a dynamic density layout and time-phased acquisition strategy is combined; through multi-mode complementation of an electrode array, an ultra-wideband radar, a distributed optical fiber and an MEMS vibration sensor, a dominant sensing mode is automatically switched in a conductive clay area, temperature gradient interference is avoided through night acquisition, the penetration depth is increased to 15 meters through multi-band radar fusion, and metal interference is inhibited; the detection precision and the anti-interference capability in a complex medium environment are remarkably improved, and the problems of high false alarm rate and high omission ratio of a traditional method are effectively solved.

The invention discloses a preparation method of a rare earth composite fluorine removal agent, the rare earth composite fluorine removal agent and application. The preparation method of the rare earth composite fluorine removal agent comprises the following steps that S1, a heavy metal capturing agent is added into rare earth slag raffinate for metal impurity adsorption treatment, the heavy metal capturing agent is removed after adsorption treatment, and intermediate treatment liquid is obtained; s2, preheating the intermediate treatment liquid to obtain a preheated material; s3, evaporating and concentrating the preheated material to obtain a concentrated solution; and S4, cooling and crystallizing to obtain the rare earth composite fluorine removal agent. According to the process for preparing the rare earth composite fluorine removal agent for water treatment through resourceful treatment on the rare earth raffinate and the fluorine removal agent product prepared by the process, the efficient fluorine removal agent is prepared from cheap and easily available raw materials.

The invention relates to the technical field of quartz sand purification, in particular to a high-purity quartz sand purification method and equipment. 2, a magnetic separation stage; 3, an acid leaching stage; 4, an ultrasonic-assisted cleaning stage; 5, a high-temperature chlorination treatment stage; according to the quartz sand purification method, various impurities such as magnetic impurities, non-magnetic metal impurities and silicate impurities in the quartz sand can be deeply removed through the synergistic effect of multiple steps such as pretreatment, magnetic separation, acid leaching, ultrasonic-assisted cleaning and high-temperature chlorination treatment, the purity of the quartz sand reaches 99.999% or above, the strict requirements of high-end fields such as semiconductors and photovoltaics are met, and the method is suitable for industrial production. The purification steps are closely linked to form a modular purification process, and meanwhile, advanced technologies such as ultrasonic-assisted cleaning and high-temperature chlorination treatment are adopted, so that the impurity removal efficiency is remarkably improved, the purification time is shortened, and the energy consumption and the use amount of chemical reagents are reduced by optimizing the process and equipment.

The invention discloses an actinide purification method and device, and belongs to the technical field of medical radioactive isotope separation and purification. The method comprises the following steps: passing a thorium target solution containing actinide through a cation exchange column, and leaching with inorganic acid to obtain a first effluent containing Ac < 3 + >; enabling the first effluent containing the Ac < 3 + > to pass through a TK221 resin extraction column to obtain a second effluent containing the Ac < 3 + >; the second effluent containing Ac3 + passes through a TRU resin extraction column, and actinide is obtained. The TK221 resin also contains phosphine oxide and a small amount of long alkyl chain alcohol on the basis of diglycolamide, and shows better performance on purification of Ac < 3 + >. Meanwhile, the elution acidity in the TRU resin separation process is properly improved, and the outflow speed of Ac, La and Ce can be delayed, so that the effect of separating Ac from La and Ce is achieved, and the yield of 225Ac is improved while the concentration of metal impurities is reduced.

This invention belongs to the field of wastewater treatment technology, specifically relating to a method for removing metallic impurities from acidic copper-containing etching wastewater at room temperature and pressure. The method includes the following steps: S1, adding an oxidant to the acidic copper-containing etching wastewater to conduct an oxidation-reduction reaction, obtaining a pretreatment solution; S2, adding phosphoric acid or soluble phosphate to the pretreatment solution, adjusting the pH to 1.3-1.7 using a pH adjuster, stirring, and filtering to obtain a purified copper-containing solution. The method provided by this invention achieves high removal rates for Fe, Ni, Zn, Ca, and Mg, while maintaining a high copper ion content. It can recycle and regenerate high-purity copper salt products for application in food, cosmetics, medical, electroplating, and other fields, while also reducing hazardous waste generation, improving economic efficiency, and significantly reducing costs.

The invention relates to a method for preparing high-purity quartz sand by burning organic silicon as a raw material, and belongs to the technical field of synthesis of quartz sand. The method comprises the following steps: introducing purified organic silicon into a combustor, and combusting to obtain nano silicon dioxide powder; then sintering is carried out to remove moisture, hydroxyl and carbon impurities on the surface of the powder, sintered silicon dioxide powder is obtained, and acid leaching and cleaning are carried out to remove metal impurities on the surface and in the powder; roasting the cleaned silicon dioxide powder in a chlorine atmosphere to remove moisture, hydroxyl and residual metal impurities; and carrying out high-temperature densification treatment on the roasted silicon dioxide powder, and then crushing, grinding and screening to obtain the high-purity quartz sand. The particle size of the prepared high-purity quartz sand ranges from 50 micrometers to 300 micrometers, the purity is larger than or equal to 99.999%, and the apparent density is larger than or equal to 2.1 g / cm < 3 >. The method breaks through the limitation of natural mineral purification, and provides a brand new path for large-scale production of high-added-value quartz sand.

The invention relates to a quartz sand pickling process. The quartz sand pickling process comprises the following steps: S1, preparing a pickling solution; s2, under the condition of 100 + / -2 DEG C, quartz sand is soaked in acid liquor for 7-10 hours, and stirring is conducted at the speed of 1-2 r / min; and S3, cooling to below 50 DEG C after pickling, separating out quartz sand, washing for multiple times until the pH is neutral, and then drying to obtain a finished product. The mixed acid liquor of hydrofluoric acid and hydrochloric acid is adopted, and efficient impurity removal is achieved through the optimized acid liquor proportion. HF has strong complexing ability and can form soluble complexes with metal impurities in the quartz sand, and HCl dissolves metal oxides to generate soluble chlorides. And through combined regulation and control of high-temperature short-time stirring and low-speed stirring, the chemical reaction rate is further accelerated, and thoroughness and uniformity of impurity removal are ensured.

Natural renewable resources are used as raw materials, efficient and environment-friendly catalytic performance is achieved through multi-stage optimization, coconut shells, fruit shells, reeds and wood chips are used as base materials in the process, a channel template is introduced after fine crushing, a graded pore structure is constructed, and the mercury-free catalyst is prepared. Dynamic extrusion forming and program temperature control carbonization-activation technologies are adopted to form an active carbon skeleton with a high specific surface area, a pulsating pressure impregnation system is innovatively designed, ultrasonic vibration is combined to strengthen copper chloride solution permeation, deep and uniform loading of active components is realized, and a mixed pickling process is developed in a matched manner. Metal impurities are efficiently removed through the synergistic effect of hydrochloric acid and citric acid, and the obtained catalyst has three-dimensional through pore channels and high-activity component dispersity, can replace a traditional mercury-containing catalyst to be applied to the fields of vinyl chloride synthesis and the like, remarkably reduces the risk of environmental pollution, improves the reaction selectivity and prolongs the service life of the catalyst, and is suitable for industrial production. And a technical support is provided for green transformation of the chemical industry.

The invention relates to a continuous production method of high-purity tetraethoxysilane, and belongs to the technical field of tetraethoxysilane preparation. The method comprises a raw material pretreatment stage and a purification and rectification stage: in the pretreatment stage, silicon tetrachloride and ethanol are subjected to an esterification reaction in a molar ratio of 1: (3-4) under the protection of nitrogen, the pH is adjusted to be neutral through triethylamine, and triethylamine hydrochloride is removed through reduced pressure distillation; then, a cerium oxide-molecular sieve composite adsorbent with the specific surface area larger than or equal to 800 m / g and the pore diameter of 2-5 nm is adopted for dehydration under the pressure of 0.8-1.2 MPa till the water content is smaller than or equal to 5 ppm, and volatile impurities are removed through high-purity nitrogen purging; in the purification stage, metal ions and Cl are synergistically removed through a titanate modified resin layer and a nano TiOtube layer, and then step-by-step separation is performed through a four-stage differential pressure rectifying tower. Through collaborative optimization of structural design of the composite adsorbent, construction of an organic-inorganic hybrid interface of the resin layer and pressure gradient rectification, 72-hour continuous production is achieved, the single-pass yield of the product is 92%, and the total amount of metal impurities is smaller than or equal to 5 ppb.

The invention discloses a preparation method of regenerated glass fiber reinforced PA6 plastic particles based on a fan blade, and the preparation method comprises the following steps: crushing the fan blade and removing metal impurities to obtain a crushed material; the crushed material is subjected to pyrolysis treatment, and a primary treatment material is obtained; performing low-temperature oxidation treatment on the primary treatment material to obtain a secondary treatment material; the secondary treatment material is placed in an impregnating compound to be subjected to impregnating treatment, and surface-modified regenerated glass fibers are obtained; mixing the regenerated glass fiber with a resin matrix to obtain a mixed material; and melting the mixed material, and carrying out injection molding extrusion to obtain the recycled glass fiber reinforced plastic particles. According to the preparation method of the reinforced PA6 plastic particles based on the regenerated glass fibers of the fan blades, the pure glass fibers can be recycled from the fan blades, the reinforced plastic particles can be prepared after the recycled glass fibers are mixed with the resin, and further high-value utilization of recycled products is achieved.

The invention belongs to the technical field of wastewater treatment, and particularly relates to a method for removing metal impurities from acidic copper-containing etching wastewater at normal temperature and pressure. The method for removing the metal impurities from the acidic copper-containing etching wastewater at normal temperature and pressure comprises the following steps: S1, adding an oxidizing agent into the acidic copper-containing etching wastewater to carry out oxidation-reduction reaction to obtain a pretreatment solution; and S2, phosphoric acid or soluble phosphate is added into the pretreatment solution, the pH is adjusted to 1.3-1.7 through a pH adjusting agent, stirring and filtering are conducted, and the purified copper-containing solution is obtained. According to the method, the removal rate of Fe, Ni, Zn, Ca and Mg is high, high-content copper ions can be kept, a high-purity copper salt product can be recycled and regenerated to be applied to the fields of food, cosmetics, medical treatment, electroplating and the like, hazardous waste can be reduced, economic benefits are improved, and cost is greatly reduced.

The invention relates to the field of industrial silicon melt purification, and discloses an industrial silicon melt purification method based on directional solidification and composite adsorption, which comprises the following steps: S1, multi-stage directional solidification pre-enrichment: carrying out primary directional solidification treatment on an industrial silicon melt, and controlling the solidification rate to be 0.5-5mm / min and the temperature gradient parameter, most of metal impurities in the melt are pre-enriched in a specific area; s2, dynamic targeted adsorption: in or after the primary directional solidification process, an efficient composite adsorbent is dynamically and continuously added into an impurity-rich area of the melt or the whole melt in batches, and the composite adsorbent has selective adsorption capacity for different impurities; and S3, intelligent regulation and control: constructing a full-flow adaptive intelligent dynamic regulation and control system based on digital twinning and AI algorithms. Compared with the prior art, the method has the advantages that the impurities are efficiently and stably removed, the grain structure is accurately modified, and meanwhile, the green and low-carbon production target is achieved.

The invention relates to the technical field of card breaking machines, in particular to a card breaking machine for waste card treatment, which comprises a bottom plate, a card breaking mechanism is arranged at the top end of the bottom plate, protective shells are arranged on two sides of the card breaking mechanism, a card recycling mechanism is arranged at one end of the bottom plate, and the card recycling mechanism is matched with the card breaking mechanism. The card crushing mechanism comprises a main body frame arranged in the middle of the top end of the bottom plate, a supporting frame is arranged at the top of the main body frame, a cover plate is arranged at the top of the supporting frame, a card pressing plate is arranged on one side of the supporting frame, and through cooperative work of a card crushing cutter set and a crushing assembly, cards are thoroughly crushed to avoid information leakage; and rapid disassembly and assembly of the tile breaking mechanism and the recycling box are achieved through cooperation of a tile assembling groove and a butt joint block, meanwhile, the equipment maintenance time and the labor cost are reduced, the tile breaking device meets the tile breaking treatment requirements of different scenes, and metal impurities are separated through an L-shaped plate and a filter plate.

The invention relates to a semiconductor device manufacturing technology, and aims to provide a preparation method of refined coke powder and high-purity isostatic pressing graphite. The method comprises the following steps: by taking calcined petroleum coke or calcined pitch coke as a raw material, crushing and grinding to obtain primary coke powder, then carrying out high-temperature halogen impurity removal treatment in a continuous heating manner, and introducing Freon gas in the process; cooling to obtain impurity-removed coke powder; and carrying out dispersion, grinding, shaping treatment, airflow classification and magnetic separation to obtain refined coke powder. According to the method, the impurity content is greatly reduced from the raw material end, the situation that a large number of metal impurities generated during smashing and grinding treatment cannot be eliminated in the graphitization process due to the fact that the metal impurities are located below the surface layer of a blank can be avoided, and the internal impurity content of a final graphite product is smaller than 20 ppm; higher tap density can be obtained, and a better mixing and kneading effect is realized; the porosity of an isostatic pressing graphite product can be reduced, the microstructure of a graphite material is effectively improved, and the corrosion resistance of the graphite material is effectively improved.

The invention discloses a low-cost high-first-effect micron silicon negative electrode material and a preparation method and application thereof. The preparation method comprises the following steps: treating the surface of micron silicon by adopting an oxidant solution to form a silicon dioxide passivation layer, and then carrying out surface modification by using a silane coupling agent; the method comprises the following steps: performing acid-base alternate soaking treatment on a biomass carbon source to reduce the content of metal impurities; mixing the delimed biomass carbon source, the composite carbon source and the pretreated micron silicon, firstly adding a weak acid catalyst for hydrothermal reaction to form a hard carbon inner layer, then adding a weak base catalyst for regulating the pH value of the system to alkalescence in batches, and continuing hydrothermal reaction to form a soft carbon outer layer; and washing and drying the product, and carrying out carbonization treatment in an inert atmosphere to obtain the composite coated micron silicon material. The first efficiency of the material is greater than or equal to 92%, the 1C 1000-time circulation capacity retention ratio is greater than or equal to 82%, the raw material cost is low, the process is simple, and the material is suitable for lithium ion batteries in the fields of power, energy storage and consumer electronics.

The invention relates to the technical field of crystalline silicon growth equipment, and provides a composite heat preservation cover for a crystalline silicon growth reduction furnace and a preparation method, the composite heat preservation cover comprises a heat insulation layer and a function protection lining, and the heat insulation layer is arranged on the outer side of the function protection lining; the heat insulation layer is made of a high-purity fiber heat insulation material or a ceramic fiber heat insulation material, the metal impurity content of the heat insulation layer is smaller than 100 ppm, and the heat conductivity coefficient is smaller than or equal to 0.1 W / (m.K); the function protection lining is made of a high-purity and high-density carbon-ceramic composite material, and the metal impurity content of the high-purity and high-density carbon-ceramic composite material is smaller than or equal to 200 ppm; or the functional protection lining is made of a carbon-carbon composite material, and a silicon carbide coating and / or a silicon nitride coating are / is arranged on the surface of the functional protection lining. The high-purity and high-density carbon-ceramic composite material lining is compounded with the efficient thermal insulation material, so that high-speed gas scouring protection, corrosive atmosphere blocking and accurate axial heat flow regulation and control are synchronously realized. Compared with a traditional structure, the power consumption of the structure is reduced by more than 20%, and the service life reaches more than 6 months.

The invention discloses a preparation method of electronic-grade high-purity manganese metal, which comprises the following steps: taking 99.8% manganese metal as an anode in an electrolytic bath, additionally arranging an ion diaphragm bag on the anode, taking a titanium plate as a cathode, and taking a manganese nitrate solution purified and adsorbed by alpha-manganese dioxide and chelating resin containing iminodiacetic acid group as an electrolyte. The method effectively avoids pollution of non-metal impurities and metal impurities, and has the technical advantage of high purity of the obtained manganese metal.

The invention discloses a method for preparing high-purity octamethylcyclotetrasiloxane, and belongs to the technical field of octamethylcyclotetrasiloxane purification. The invention treats crude octamethylcyclotetrasiloxane by combining distillation-adsorption-re-distillation, thereby overcoming the problem that trace impurities are difficult to be removed by a single distillation method. The distillation-adsorption-re-distillation method is combined for operation, and the advantages of each method are brought into play, and impurities such as hexamethylcyclotrisiloxane and decamethylcyclopentasiloxane with similar boiling points are reduced, so that the octamethylcyclotetrasiloxane product reaches a very high purity. The invention adopts an adsorption treatment method to adsorb and separate phosphorus-containing and boron impurities and metal impurities in alkane residues in the octamethylcyclotetrasiloxane, thereby obtaining electronic-grade octamethylcyclotetrasiloxane, and the product purity can reach more than 99.99%.

To provide a carbon nano-tube that can reduce metallic impurities and have excellent dispersibility.SOLUTION: A carbon nano-tube is subjected to graphitization treatment and then pulverization treatment to have a particle size D50 of 100 μm or less.SELECTED DRAWING: None

The invention discloses a preparation method of high-purity fused quartz powder, and the preparation method specifically comprises the following steps: S1, crushing; s2, fully washing the quartz powder with water, and then removing impurities; s3, feeding the crushed particles subjected to impurity removal into a pickling tank for pickling; s4, dissolving the crude product in two times of alkaline solution, carrying out alkali washing treatment, and carrying out ultrasonic cleaning after the treatment is completed; s5, the cleaned raw materials are fed into a heating furnace to be subjected to high-temperature heat treatment; s6, magnetic separation is repeated; and S7, further crushing into fused quartz sand of which the particle size is less than 2mm by adopting an impact crusher. According to the preparation method of the high-purity fused quartz powder, circulating pickling is adopted, the optimal pickling condition acid concentration, acid dosage, pickling time, pickling temperature and the like are selected, metal impurities are effectively removed, and the purification effect is good; repeated magnetic separation is carried out under high and low field intensities, the magnetic separation effect is good, magnetic impurities are preliminarily and efficiently removed, and the purity of the whole manufactured product is high.

The invention provides a production device and process for recovering electronic-grade phosphoric acid from waste etching liquid. The device comprises a raw material storage tank, a multi-stage filtration system, a phosphoric acid evaporation kettle, a purification system, a mixed acid storage tank and a neutralization reaction and crystallization system. The waste etching liquid enters an evaporation kettle after being subjected to multi-stage filtration to remove suspended solid particles, and phosphoric acid is separated from volatile nitric acid and acetic acid; and condensing the volatile acid into mixed acid for storage, and removing metal ions from the semi-finished phosphoric acid through a purification system to obtain the electronic-grade phosphoric acid. The mixed acid reacts with alkali to generate a mixed solution of sodium acetate and nitric acid, sodium acetate crystals are separated out through evaporation and concentration, a solid product is obtained after separation, nitric acid is obtained by condensing gas, and suspended particles and metal impurities are subjected to incineration treatment. Through the steps of filtering, negative-pressure evaporation, neutralization and crystallization and the like, the process realizes efficient recovery of electronic-grade phosphoric acid and byproducts of sodium acetate and nitric acid, and has the characteristics of high resource recovery rate and low pollution emission.

The utility model relates to the field of wet tissue processing, in particular to a metal foreign matter detection device which comprises a workbench, table legs, a conveying mechanism and a detection classification mechanism. The conveying mechanism is arranged on the outer side of the workbench and used for fixing wet tissues and conveying the wet tissues to a detection point; the detecting and classifying mechanism is arranged on the top of the workbench and used for detecting the content of metal foreign matter of the wet tissue at a fixed point and separating qualified products from defective products. Through the arrangement of the conveying mechanism, wet tissues are conveyed and detected at fixed points, continuous and rapid metal impurity detection can be realized, manual intervention is reduced, the production efficiency is improved, meanwhile, the consistency of a detection environment can be ensured, and the influence of factors such as position change or vibration on a detection result is reduced, so that the detection accuracy is improved, and the detection efficiency is improved. And the wet tissues can pass through the metal detector one by one, so that missing detection is effectively avoided, and each wet tissue is ensured to be fully detected.

The invention provides a method for purifying silicon from an organic silicon synthesis waste contact body and application of the method in preparation of a silicon-based alloy. The method comprises the following steps: pickling the waste contact body by using acid liquor; acid liquor is added into the silicon enriched material obtained through acid pickling separation, acid leaching slurry is obtained, the acid leaching slurry is diluted, and waste contact electrolyte is obtained; adjusting the pH value of the waste contact electrolyte to 5.5-6.5, and introducing the waste contact electrolyte into an electrolytic cell; introducing oxygen-containing gas near a cathode plate of the electrolytic bath, and introducing direct current on an electrode plate of the electrolytic bath to carry out electrolytic reaction; adjusting the pH value of the electrolyte in the electrolytic bath to 7.0-7.5, and continuing the electrolytic reaction to obtain a metal precipitate; and separating the liquid part and the precipitation part in the electrolytic bath, adding water into the precipitation part, fully stirring, and carrying out centrifugal separation, washing and drying treatment to obtain the silicon powder. According to the method, metal impurities and organic matters in the waste contact bodies can be effectively removed, high-purity silicon is obtained, and the high-quality silicon-based alloy is prepared.

The invention belongs to the field of metal purification, and particularly relates to a metal impurity element separation device and method. The invention provides a magnesium-zinc separation method and device aiming at the problem that magnesium and zinc are difficult to separate in a traditional vacuum distillation technology. According to the magnesium-zinc separation method, a magnetic field is used for rapidly stirring a metal melt, and it is ensured that the flowing direction of the metal melt is parallel to a solid / liquid interface at the front edge of the solid / liquid interface. The stirring in the form can effectively reduce the thickness of a solute enrichment layer, increase the liquid phase diffusion coefficient and reduce the effective distribution coefficient. The device is composed of a crucible unit, a crystallizer unit, a magnet stirring unit, a vacuum unit and the like. The device utilizes the rotation of the magnet to promote the magnesium melt to flow, reduce the effective distribution coefficient and obtain the high-purity magnesium ingot. The device is simple in structure, convenient to operate and beneficial to application and popularization.

The invention discloses a multi-material high-speed 3D printer, and relates to the technical field of 3D printers, the multi-material high-speed 3D printer comprises a printer assembly, a forming assembly is arranged in the printer assembly, and the forming assembly comprises a forming cavity. According to the multi-material high-speed 3D printer, when the interior of a forming cavity works, inert gas starts to flow in the forming cavity, by starting a suction pump, under the action of working pressurization of the suction pump, the inert gas can be continuously pumped out of the interior of the forming cavity, smoke dust and metal impurities doped in the inert gas can be filtered out when passing through a filter screen plate, and therefore the smoke dust and the metal impurities are filtered out; clean gas is conveyed out, under the action of airflow, a magnetic suction plate is blown, then a rotating rod rotates in a rotating groove, metal impurities are adsorbed through the magnetic suction plate, the metal impurities are adsorbed to the magnetic suction plate, and when the metal impurities need to be taken out, the rotating rod can be taken out by opening a sealing plate; and smoke dust and metal in the inert gas can be prevented from entering the environment.

The invention relates to a silver recovery technology, in particular to a method for preparing high-purity silver powder by recovering silver from retired photovoltaic module cells, which comprises the procedures of pretreatment, leaching treatment, suction filtration treatment, silver precipitation treatment, silver chloride precipitation and purification treatment, silver ammonia solution reduction and the like. The method comprises the following steps: by taking a disassembled retired photovoltaic module battery piece as a raw material, firstly, removing dust on the surface of the battery piece and metal impurities partially attached to the surface of the battery piece through pretreatment, leaching the cleaned battery piece by using a nitric acid solution, carrying out suction filtration by using a suction filtration machine, and separating to obtain silicon slag and a silver nitrate solution; the method comprises the following steps: adding a chlorinating agent into a silver nitrate solution, reacting to generate silver chloride precipitate, dissolving the separated silver chloride precipitate by using ammonia water to form a silver-ammonia solution, and finally adding a reducing agent into the silver-ammonia solution to obtain high-purity silver powder and ammonia water; compared with the conventional technology, the method for recovering silver has the advantages of low cost, no wastewater generation and simpler process, and meets the requirements of economy, high efficiency and environmental protection.

The invention provides a lithium ion battery negative electrode graphite recovery method which comprises the following steps: putting powder obtained by stripping into an acid solution for soaking, and removing impurities; the powder is taken out of the acid liquor, the powder is cleaned, and the cleaned powder is dried; grinding and crushing the dried powder to obtain powder, and carrying out heat treatment on the powder in a preset high-temperature environment to remove impurities; the powder subjected to heat treatment is put into a reaction kettle, an adhesive is added, stirring is conducted, and secondary particles are obtained; and demagnetizing the secondary particles to obtain the negative electrode graphite. After metal impurities are removed through acid pickling, organic impurities are synchronously removed through high-temperature heat treatment, surface defects are repaired, a binding agent is added, stirring is conducted to form secondary particles, the gram volume and the first effect are improved, the graphite surface structure is complete, obvious defects and damage do not exist, the first effect and the gram volume of graphite are effectively improved, and better cycle performance is achieved.

The invention provides a method for synthesizing low-oxygen high-alpha-phase silicon nitride powder through direct nitridation of silicon sawdust, and belongs to the technical field of silicon nitride preparation. The method comprises the following steps: carrying out acid pickling, impurity removal and purification treatment on silicon sawdust to obtain a silicon raw material of which the main metal impurities are less than 10ppm and the oxygen content is less than 2%; the silicon raw material and a regulator are mixed according to a preset proportion and subjected to ball milling treatment, a mixed material is obtained, and the regulator comprises sodium chloride and carbon powder; introducing a gaseous nitrogen source, and carrying out vacuum gradient heating nitridation treatment on the mixed material to obtain a silicon nitride crude product; and sequentially carrying out acid pickling, solid-liquid separation, cleaning and drying post-treatment on the silicon nitride crude product to obtain the low-oxygen high-alpha-phase silicon nitride powder. According to the invention, the silicon sawdust is subjected to pickling purification, and the obtained silicon sawdust is directly nitrided at low temperature under the assistance of sodium chloride and carbon powder to synthesize alpha-phase silicon nitride; and then the high-dispersion and high-purity alpha-phase silicon nitride powder can be obtained through an acid pickling-water washing-drying process. The silicon nitride product prepared by the method can be used as a raw material of silicon nitride ceramic.

The invention belongs to the technical field of secondary batteries, and particularly relates to a regeneration method of a lithium iron phosphate positive electrode material and a regenerated lithium iron phosphate positive electrode material. The regeneration method of the lithium iron phosphate positive electrode material provided by the invention comprises the following steps: pyrolyzing the lithium iron phosphate positive electrode material to be repaired to remove volatile impurities; carrying out activating treatment on a pyrolysis product and an activating agent; dissolving out metal impurity ions from the activated product in organic acid, and filtering, washing and drying to obtain a purified activated product; and mixing the purified activated product with a lithium source and a carbon source, and sintering. Impurities in the waste lithium iron phosphate positive electrode material are further removed through low-temperature pyrolysis, activation, metal impurity ion removal and sintering, crystal structure defects are repaired, the obtained regenerated lithium iron phosphate is high in purity and complete in crystal structure, the specific capacity and cycle performance of the lithium iron phosphate positive electrode material are improved, and the service life of the lithium iron phosphate positive electrode material is prolonged. The performance level equal to that of a commercial lithium iron phosphate positive electrode material is achieved.

The invention provides a method for purifying silicon waste of a solar cell. The method comprises the following steps: cleaning the silicon waste with an organic solvent, and removing impurities with a mixed acid solution; the organic solvent is a polar organic solvent of which the dielectric constant is greater than or equal to 18.3 and the dipole moment is greater than or equal to 1.66 D; the molar ratio of hydrofluoric acid in the mixed acid solution to total acid is 1-6%, and the molar concentration of the total acid in the mixed acid solution is 1.5-4 mol / L. According to the method, the crystalline silicon cutting waste is cleaned through the polar organic solvent, metal impurities in the crystalline silicon cutting waste can be better removed with the assistance of the mixed acid solution with the specific concentration and molar ratio, and the recovery rate of silicon in the crystalline silicon cutting waste is greatly increased; and moreover, the use amount of hydrofluoric acid in the mixed acid solution is greatly reduced, and production of high-purity silicon with high recovery rate is possible.