Spherical Silica Powder Production
Spherical silicon powder has relatively high purity, very fine particles, good dielectric properties and thermal conductivity, and has the advantages of low expansion coefficient. It is widely used in large-scale integrated circuit packaging, aerospace, coatings, medicine and daily cosmetics, and is an irreplaceable important filler.
There are two methods for preparing spherical silicon micropowder: physical and chemical method and chemical method. The physical and chemical methods mainly include flame method, deflagration method, high temperature melt spray method, plasma method and self-propagating low temperature combustion method. The chemical method mainly includes gas phase method, liquid phase method (sol-gel method, precipitation method, microemulsion method), chemical synthesis method, etc.
In the production process of spherical silicon micropowder, strict control of each production link is the key to ensure that the product quality meets the standards.
The main raw material of spherical silicon micropowder is angular molten or crystalline silicon micropowder.
Stability of raw materials
The raw materials used to produce spherical silicon micropowder are preferably angular silicon micropowder processed from the same ore vein and the same production process, so as to maximize the uniformity of the raw materials and ensure that the products with high spheroidization rate are produced under the condition that the spheroidization temperature, gas supply, feed amount, pressure, flow rate and other factors remain unchanged.
The physical and chemical indicators of the raw materials should be controlled within a certain range
The physical and chemical indicators of the raw materials fluctuate too much, which will not only affect the spheroidization temperature, but also affect the dispersion of the spheres.
Raw material particle size and particle size distribution
Different particle sizes have different heating areas, and their passivation temperature points after heating are also different.
Raw material particle dispersibility
During the processing of angular silicon micropowder, especially ultrafine angular silicon micropowder, secondary agglomeration of powder often occurs due to the increase of surface energy.
Moisture content of raw materials
If the angular silicon micropowder used as the raw material of spherical silicon micropowder is affected by factors such as improper protection, too long storage time, and excessive environmental humidity, it will cause the powder to absorb moisture, have high moisture content, and agglomerate, which will also affect the spheroidization effect of spherical silicon micropowder.
Radioactive elements in raw materials should be low
For the raw materials for producing low-radiation spherical silicon micropowder, only when the radiation elements themselves (such as uranium U, thorium Th, etc.) are very low can the products produced meet the requirements of low-radiation spherical silicon micropowder.
There are two links in the surface modification of spherical silicon micropowder. One is to disperse the secondary agglomerated particles of spherical silicon micropowder raw materials - angular silicon micropowder, especially ultrafine angular silicon micropowder, and first perform surface activation treatment to disperse the particles before sphericalization. This requires that the surface dispersant used must be completely volatilized at high temperature, otherwise it will cause carbon deposits in the spherical silicon micropowder, affecting product quality.
The second is the late modification of spherical silicon micropowder. When silicon micropowder is used as an inorganic filler and mixed with organic resin, there are problems of poor compatibility and difficulty in dispersion, which leads to poor heat resistance and moisture resistance of materials such as integrated circuit packaging and substrates, thereby affecting the reliability and stability of the product. In order to improve the problem of interface bonding between silicon micropowder and organic polymer materials and improve its application performance, it is generally necessary to modify the surface of silicon micropowder.
The key to efficient powder modification
Powder surface modification, also known as surface modification, surface treatment, etc., refers to the use of certain methods (physical, chemical or mechanical, etc.) to treat, modify and process the surface of particles, and purposefully change the physical and chemical properties of the powder surface to meet the requirements of powder processing and application. Therefore, understanding the physical and chemical properties of powders is crucial to effectively change these properties of the powder surface to achieve efficient powder modification.
Specific surface area
The specific surface area of powder materials is related to their particle size, particle size distribution and porosity. For powder materials, the specific surface area is related to the particle size. The finer the particle, the larger the specific surface area; it is related to the roughness of the particle surface. The rougher the surface, the larger the specific surface area; it is greatly related to the pores on the particle surface. The specific surface area of porous powder increases sharply. The specific surface area of powder materials with developed micropores can be as high as several thousand square meters per gram.
Specific surface area is one of the most important surface properties of powder materials and one of the main bases for determining the amount of surface modifier. The amount of surface modifier is related to the specific surface area of the powder. The larger the specific surface area, the more surface modifier is required to achieve the same coverage rate.
Surface energy
The surface energy of the powder is related to its structure, the bond type and bonding force between atoms, the number of surface atoms and the surface functional groups. After the material is crushed, a new surface is generated, and part of the mechanical energy is converted into the surface energy of the new surface. Generally speaking, the higher the surface energy of the powder, the more it tends to agglomerate, and the stronger the water absorption and adhesion.
Surface wettability
The wettability or hydrophobicity of the surface of inorganic powder is one of the important surface properties of fillers for polymer-based composite materials such as plastics, rubbers, adhesives, and fillers or pigments for oily coatings.
Surface adsorption characteristics
When molecules (or atoms) in the gas phase or liquid phase collide with the surface of the powder, the interaction between them causes some molecules (atoms, ions) to remain on the surface of the powder, causing the concentration of these molecules (or atoms, ions) on the surface of the powder to be greater than that in the gas phase or liquid phase. This phenomenon is called adsorption. Powders are usually called adsorbents, and the adsorbed substances are called adsorbates. The larger the specific surface area of the powder, the more significant the adsorption phenomenon.
Surface electrical properties
The electrical properties of the powder surface are determined by the charged ions on the powder surface, such as H+, 0H-, etc. The electrical properties of powder materials in solution are also related to the pH value of the solution and the type of ions in the solution. The charge and size of the powder surface affect the electrostatic forces between particles, between particles and surfactant molecules and other chemical substances, thus affecting the cohesion and dispersion characteristics between particles and the adsorption of surface modifiers on the particle surface.
Surface chemical properties
The chemical properties of the powder surface are related to the crystal structure, chemical composition, surface adsorbents, etc. of the powder material. It determines the adsorption and chemical reaction activity of the powder under certain conditions, as well as the surface electrical properties and wettability, etc. Therefore, it has an important influence on its application performance and the interaction with the surface modifier molecules. The chemical properties of the powder surface in the solution are also related to the pH value of the solution.
Silicon carbide ceramics: photovoltaic industry applications
Silicon carbide ceramics have good mechanical strength, thermal stability, high temperature resistance, oxidation resistance, thermal shock resistance and chemical corrosion resistance, and are widely used in hot fields such as metallurgy, machinery, new energy, building materials and chemicals. Its performance is also sufficient for the diffusion of TOPcon cells in photovoltaic manufacturing, LPCVD (low pressure chemical vapor deposition), PECVD (plasma chemical vapor deposition) and other thermal process links.
Compared with traditional quartz materials, boat supports, boats, and pipe fittings made of silicon carbide ceramic materials have higher strength, better thermal stability, no deformation at high temperatures, and a lifespan of more than 5 times that of quartz materials. They can significantly reduce the cost of use and the energy loss caused by maintenance and downtime. They have obvious cost advantages and a wide range of raw materials.
Among them, reaction bonded silicon carbide (RBSC) has low sintering temperature, low production cost, and high material densification. In particular, there is almost no volume shrinkage during the reaction sintering process. It is particularly suitable for the preparation of large-sized and complex-shaped structural parts. Therefore, it is most suitable for the production of large-sized and complex products such as boat supports, boats, cantilever paddles, furnace tubes, etc.
Silicon carbide boats also have great development prospects in the future. Regardless of the LPCVD process or the boron diffusion process, the life of the quartz boat is relatively low, and the thermal expansion coefficient of the quartz material is inconsistent with that of the silicon carbide material. Therefore, it is easy to have deviations in the process of matching with the silicon carbide boat holder at high temperature, which can lead to the boat shaking or even breaking. The silicon carbide boat adopts an integrated molding and overall processing process route. Its shape and position tolerance requirements are high, and it cooperates better with the silicon carbide boat holder. In addition, silicon carbide has high strength, and the boat breakage caused by human collision is much less than that of quartz boats.
The furnace tube is the main heat transfer component of the furnace, which plays a role in sealing and uniform heat transfer. Compared with quartz furnace tubes, silicon carbide furnace tubes have good thermal conductivity, uniform heating, and good thermal stability. The service life is more than 5 times that of quartz tubes. However, the manufacturing difficulty of silicon carbide furnace tubes is very high, and the yield rate is also very low. It is still in the research and development stage and has not yet been mass-produced.
In a comprehensive comparison, whether in terms of product performance or cost of use, silicon carbide ceramic materials have more advantages than quartz materials in certain aspects of the solar cell field. The application of silicon carbide ceramic materials in the photovoltaic industry has greatly helped photovoltaic companies reduce the investment cost of auxiliary materials and improve product quality and competitiveness. In the future, with the large-scale application of large-size silicon carbide furnace tubes, high-purity silicon carbide boats, and boat supports, and the continuous reduction in costs, the application of silicon carbide ceramic materials in the field of photovoltaic cells will become a key factor in improving the efficiency of light energy conversion and reducing industry costs in the photovoltaic power generation field, and will have an important impact on the development of photovoltaic new energy.
Application of Silicon Carbide in Photovoltaic Industry
With the increasing global energy demand, fossil energy, mainly oil, coal and natural gas, will eventually be exhausted. In addition, fossil energy will also cause serious environmental pollution during use. In order to solve the above problems, renewable energy such as solar energy, wind energy, hydropower and nuclear energy have attracted people's attention.
The main way to utilize solar energy is photovoltaic power generation. Compared with other power generation technologies, photovoltaic power generation has the advantages of being green and environmentally friendly, having sufficient solar energy resources, being safe and reliable in the power generation process, and being easy to install and transport power generation equipment. It is foreseeable that the large-scale promotion of photovoltaic power generation will have a positive impact on the governance of energy and environmental crises.
According to the principle of photovoltaic power generation, when sunlight shines on photovoltaic components (such as solar panels), photons interact with electrons in photovoltaic materials, causing electrons to escape from the materials and form photocurrent, which is direct current. Since most electrical equipment is powered by AC, the direct current generated by the photovoltaic array cannot be used directly, and it is necessary to convert the direct current into alternating current to achieve photovoltaic grid-connected power generation.
The key device to achieve the above purpose is the inverter, so the photovoltaic grid-connected inverter is the core of photovoltaic power generation technology, and the working efficiency of the inverter largely determines the utilization efficiency of solar energy.
Power devices are the core components of photovoltaic grid-connected inverters. Nowadays, various semiconductor devices used in the electrical industry are mostly based on silicon (Si) materials and have developed quite maturely. Si is a semiconductor material that is widely used in various electronic tubes and integrated circuits. As the use of power semiconductor devices becomes increasingly diverse, the use of silicon devices is restricted in some applications with high performance requirements and harsh working environments. This requires people to develop semiconductor devices with better performance. As a result, wide bandgap semiconductor devices such as silicon carbide (SiC) came into being.
Compared with silicon-based devices, silicon carbide devices exhibit a series of remarkable excellent properties:
(1) High breakdown electric field strength: The breakdown electric field strength of SiC is about 10 times that of Si, which makes SiC devices have higher blocking voltage and can work under higher electric field conditions, which helps to improve power density.
(2) Wide bandgap: SiC has a lower intrinsic carrier concentration at room temperature, which will lead to lower on-resistance in the on state.
(3) High saturation drift velocity: SiC has a higher electron saturation drift velocity, which helps it reach a steady state faster during the switching process and reduces energy loss during the switching process.
(4) High thermal conductivity: SiC has a higher thermal conductivity, which will significantly improve the power density, further simplify the design of the heat dissipation system, and effectively extend the device life.
In short, silicon carbide power devices provide the required low reverse recovery and fast switching characteristics to achieve "high conversion efficiency" and "low energy consumption" of photovoltaic inverters, which is crucial to improving the power density of photovoltaic inverters and further reducing the cost per kilowatt-hour.
Application of ultrafine grinding equipment in the field of traditional Chinese medicine
Ultrafine grinding technology can improve the extraction rate and bioavailability of traditional Chinese medicine, enhance the quality of traditional Chinese medicine preparations, and save resources. Traditional Chinese medicine can be further made into various dosage forms after ultrafine grinding, and has broad development prospects.
Ultrafine grinding technology is an advanced technology that uses mechanical or fluid dynamics to deagglomerate 0.5~5.0mm materials to micrometer or even nanometer levels. Compared with traditional grinding, it has the advantages of saving materials, fast grinding speed, and uniform and fine powder particle size.
Depending on the grinding media, ultrafine grinding technology is divided into dry and wet grinding. Dry grinding is to grind materials under dry conditions, which can produce ultrafine powders with good adsorption, expansion and water solubility; wet grinding is to grind (semi) fluid materials. Compared with dry grinding, it has the advantages of less dust hazard and less heat generation, and at the same time has homogenization and emulsification effects, making the product taste more delicate.
Based on the inherent properties of Chinese medicinal materials, Chinese medicinal ultrafine powder is mostly prepared by adding mechanical force. There are three common mechanical equipment.
Jet mill is also called fluid energy mill. The core components are nozzle and crushing chamber. The working principle is to use high-speed airflow or superheated steam as the impact carrier, spray it from the nozzle, provide energy for the fracture behavior of the material, cause the material crack to become unstable and open and expand under the action of external force, and the macroscopic manifestation is the change of material particle size. Jet mill with high-speed airflow as the impact carrier is often used for Chinese medicine crushing, which can be divided into the following 5 types: horizontal disc type, circulating tube type, opposite spray type, impact plate target type, fluidized bed type.
Jet mill is suitable for Chinese medicine with crisp texture, heat sensitivity and low melting point, but not for medicinal materials containing volatile components. The product after crushing has uniform particle size distribution, high classification accuracy, strong affinity, and retains the inherent properties of the particles. Therefore, this technology has become the preferred method for the development of various high-performance micropowder materials.
High-speed mechanical impact mill
The high-speed mechanical impact mill uses a rotor rotating at high speed around the axis to transfer momentum to the material, causing the material to collide violently with the liner to obtain ultrafine powder. The grinding, shearing and eddy current effects generated in this process can promote the formation of new powder surfaces.
This equipment is convenient for feeding, occupies a small area, has high crushing efficiency, and has adjustable crushing particle size. It is widely used in the crushing of medium and low hardness Chinese medicines; but it has a thermal effect during the crushing process and is not suitable for heat-sensitive and low-melting-point Chinese medicines. This equipment mainly relies on high-speed operation of parts for crushing, which will cause serious wear of parts and pollution of Chinese medicines is inevitable. Therefore, the development of high-wear-resistant materials is an important way to promote the development of such equipment.
The vibration mill includes grinding media, grinding bowl and eccentric excitation device. Its working principle is complex and multi-scale. The eccentric mechanism drives the bowl to vibrate periodically at high frequency. The grinding media moves accordingly and produces multiple forces on the material, aggravating the extension of cracks in the material, thereby breaking the external structure.
The vibration mill is suitable for crushing Chinese medicines of different hardness, and the particle size distribution of the obtained particles is narrow. If the vibration mill is equipped with a cooling device, it can also achieve low-temperature crushing of heat-sensitive, low-melting-point and volatile Chinese medicinal materials.
Ultrafine grinding technology has brought new opportunities to the field of traditional Chinese medicine, but it also has some challenges, such as the energy consumption of air jet mills and the noise of vibration mills.
Application of silicon-based negative electrode materials in lithium-ion batteries
With the vigorous development of new energy vehicles, energy storage and other markets, the market size and technical level of lithium batteries and negative electrode materials continue to improve. At present, the specific capacity of commercial graphite negative electrode materials is close to the theoretical specific capacity of graphite materials, and the commercial application of silicon-based negative electrode materials has been further accelerated.
Silicon-based negative electrode materials have become a hot spot in the research of lithium-ion battery negative electrode materials due to their extremely high theoretical specific capacity. The theoretical specific capacity of silicon negative electrode materials is much higher than that of commercial graphite negative electrode materials, and the working voltage is moderate, which makes silicon-based negative electrode materials have significant advantages in improving battery energy density. However, the volume expansion and contraction of silicon during charging and discharging is too large, resulting in material cracking and fragmentation, as well as continuous thickening of SEI film, which seriously affects the cycle stability and rate performance of the battery.
In order to solve the defects of silicon-based negative electrode materials in lithium-ion battery applications, researchers have proposed a variety of technical routes, including nanotechnology, composite material technology, structural design, surface modification, electrolyte optimization, pre-lithiation, porous silicon and alloy silicon, etc.
These technical routes cover all stages from laboratory research to industrial application, alleviating the volume expansion problem through nano-sizing and composite materials technology, improving conductivity and stability through structural design and surface modification, and enhancing the overall performance of the battery by optimizing the electrolyte system. Pre-lithiation technology can improve the initial coulombic efficiency, porous silicon structure helps to alleviate volume changes, and alloy silicon can provide higher capacity and stability. The comprehensive application of these technical routes is expected to achieve high-performance, long-life and low-cost silicon-based negative electrode materials, and promote their widespread popularity in practical applications.
At present, silicon-carbon materials and silicon-oxygen materials are the two main technical routes for silicon-based negative electrodes.
Among them, silicon-carbon negative electrode materials are known for their high first coulombic efficiency, but their cycle life needs to be improved. By realizing the nano-sizing of silicon materials, the expansion and breakage problems generated during the charging and discharging process can be reduced, thereby further enhancing their cycle life. Relatively speaking, the main advantage of silicon-oxygen negative electrode materials is their excellent cycle stability, although the first efficiency is low. However, by adopting technical means such as pre-lithiation, their first efficiency can be effectively improved.
In terms of commercial applications, currently, the main commercial applications of silicon-based negative electrode materials include carbon-coated silicon oxide, nano silicon carbon, silicon nanowires and amorphous silicon alloys. Among them, carbon-coated silicon oxide and nano silicon carbon have the highest degree of commercialization, and they are usually mixed with graphite at a ratio of 5%-10%. In recent years, silicon-based negative electrode materials are gradually being industrialized.
In the field of solid-state batteries, silicon-based negative electrode materials are considered to be one of the key development directions of solid-state battery negative electrode materials due to their high theoretical energy density, excellent fast charge and discharge performance and excellent safety performance.
Next-generation communication core material: lithium tantalate
With the rapid development of the Internet of Things, artificial intelligence, and big data technology, lithium tantalate (LiTaO3) has been widely used in digital signal processing, 5G communications, guidance, infrared detectors and other fields due to its excellent properties such as piezoelectricity, acousto-optics, and electro-optics. Its single crystal film is considered to be a new material urgently needed for the development of new devices in the post-Moore era.
Lithium tantalate is a multifunctional crystal material with excellent performance. It has an ilmenite structure and is colorless or light yellow. Its crystal raw materials are abundant, its performance is stable, and it is easy to process. It can produce high-quality, large-size single crystals. Polished lithium tantalate crystals can be widely used in the manufacture of electronic communication devices such as resonators, surface filters, and transducers. It is an indispensable functional material in many high-end communication fields such as mobile phones, satellite communications, and aerospace.
Main Applications
Surface Acoustic Wave (SAW) Filter
Surface acoustic wave filter is a special filtering device made by using the piezoelectric effect of piezoelectric crystal oscillator materials and the physical characteristics of surface acoustic wave propagation. It has the advantages of low transmission loss, high reliability, large manufacturing flexibility, analog/digital compatibility, and excellent frequency selection characteristics. Its main components include transmission line, piezoelectric crystal and attenuator. When the signal reaches the surface of the piezoelectric crystal through the transmission line, surface acoustic waves will be generated. The speed of surface acoustic waves of different frequencies is different during propagation. By reasonably designing the geometric shape and transmission parameters of the piezoelectric crystal and the interdigital transducer and the existence of the reflector, filtering effects of different frequencies can be achieved.
Crystal Oscillator
A crystal oscillator is an energy conversion device that converts direct current into alternating current with a certain frequency. It mainly uses the piezoelectric effect of piezoelectric crystals to generate stable electrical oscillations. When voltage is applied to the two poles of the chip, the crystal will deform, thereby generating voltage on the metal sheet. Crystal oscillators are widely used in communication radio stations, GPS, satellite communications, remote control mobile devices, mobile phone transmitters, and high-end frequency counters because of their highly stable frequency AC signals. It usually uses crystals that can convert electrical energy and mechanical energy to provide stable and accurate single-frequency oscillations. Currently, commonly used crystal materials include quartz semiconductor materials and lithium tantalate chips.
Pyroelectric detector
A pyroelectric detector is a sensor that uses the pyroelectric effect to detect temperature changes or infrared radiation. It can detect the energy changes of the target in a non-contact form, thereby generating a measurable electrical signal. Its core component is a pyroelectric chip, a single crystal material with special properties, usually composed of units with opposite charges, with crystal axes and spontaneous polarization. Pyroelectric materials need to be prepared very thin, and electrodes are plated on the surface perpendicular to the crystal axis. The upper surface electrode needs to be plated with an absorption layer before it can be used. When infrared radiation reaches the absorption layer, the pyroelectric chip will be heated and a surface electrode will be generated; if the radiation is interrupted, a reverse polarization charge will be generated.
Lithium tantalate has broad application prospects in 5G communications, photonic chips, quantum information and other fields due to its large pyroelectric coefficient, high Curie temperature, small dielectric loss factor, low thermal melting point per unit volume, small relative dielectric constant and stable performance.
Ceramic materials used in tooth restorations
Dental restoration materials must undergo rigorous biological testing to ensure that they not only have the mechanical, physical, and chemical properties required for clinical use, but also have good biocompatibility. In recent years, with the continuous development of materials science and technology and the continuous improvement of people's living standards, ceramic materials, resin-based composite materials, metal materials, 3M nano-resins, glass-ceramics and other materials have gradually been widely used.
(1) Alumina ceramics
Alumina ceramics are white crystalline solids or powders with remarkable chemical stability and mechanical properties. As a dental restoration material, alumina has the color and light transmittance that match that of real teeth, meets aesthetic requirements, and has the advantages of weak toxicity to fibrous tissue in vitro.
(2) Zirconia ceramics
At the end of the 20th century, zirconia was developed as a dental restoration material. Zirconia ceramics have significant wear resistance, corrosion resistance, and high temperature resistance, good optical effects, are suitable for tooth restoration, and have high strength. Zirconia has strong stability and good biocompatibility. Compared with alumina, it has higher wear resistance and toughness. It is suitable for the production of valves, composite ceramic artificial bones, hip joints, bones, and tooth roots.
(3) Bioactive glass
Bioactive glass is an artificial biomaterial that can bond with bone tissue and connect with soft tissue at the same time. It has excellent properties such as biocompatibility, low toxicity, bone guidance and bone formation, and has good hemostasis and antibacterial effects. It can achieve specific biological and physiological functions when implanted in the body. Bioactive glass can be used as bone transplantation, bone filling material, alveolar ridge maintenance and reconstruction material, and oral implant coating material.
(4) Hydroxyapatite ceramics
Hydroxyapatite belongs to the hexagonal crystal system and is a typical bioactive ceramic. Its composition is close to the inorganic components of natural bone tissue and has good biocompatibility. It is not only safe and non-toxic when implanted in the body, but also can conduct bone growth. It is an excellent bioactive material. It is often used in the field of oral medicine for periodontal bone defect repair and artificial tooth root implants.
(5) Tricalcium phosphate ceramics
Tricalcium phosphate is an important calcium phosphate ceramic with good biocompatibility and biotoxicity. Tricalcium phosphate can be made into hollow structural components of a certain size and shape according to the requirements of degradation rate of different parts and different bone properties, and can be used to treat various orthopedic diseases. In addition, tricalcium phosphate has the biological characteristics of inducing periapical bone regeneration and pulp calcium bridge formation, and is widely used and valued in the field of oral medicine.
(6) Feldspar porcelain
Feldspar porcelain is a borosilicate feldspar glass with irregular grain structure distributed in the glass matrix. It is used in anterior tooth veneers, full crowns and posterior tooth inlays. It has good aesthetic effects and abrasion close to natural teeth. After grinding and polishing, it can be used in the mouth.
(7) Glass ceramics
Glass ceramics are polycrystalline solids with uniform and dense distribution of glass phase and crystal phase in a glass matrix obtained through a series of heat treatment procedures. They are also called microcrystalline glass. Glass ceramics have become the preferred material for aesthetic restoration of anterior teeth because of their transmittance and saturation close to natural teeth. Glass ceramics not only have excellent corrosion resistance and wear resistance, but also their flexural strength and fracture toughness can be controlled by adjusting the heat treatment process of the crystallization process. Therefore, products suitable for different uses have been developed one after another.
(8) Composite ceramics
Composite ceramics are a new type of resin-ceramic composite material that combines the characteristics of traditional ceramics with new resin process materials. Its advantage is that it can be realized using CAD/CAM technology. In addition, since composite ceramics contain a large amount of resin components, once the restoration is damaged, it is easy to repair it with resin.
The key to improving ball mill efficiency
Factors affecting grinding efficiency
Grinding efficiency is an important indicator of ball mill performance, which is crucial to improving mineral processing efficiency and reducing energy consumption.
Material properties are basic factors, and hardness, toughness, density and fracture characteristics affect the difficulty of grinding.
Mill operating parameters have a significant impact on efficiency, such as speed, filling rate, media size and type. Optimizing the speed can maximize the impact and friction, and the appropriate filling rate ensures effective contact between the material and the media. The type and size of the grinding media are also important. Media of different materials and sizes will affect the grinding efficiency. Choosing the right media can improve the grinding effect.
The choice of grinding process also affects the efficiency. Wet grinding is suitable for fine particle requirements, and dry grinding is suitable for materials with low water content.
The design and maintenance of the mill are also critical. The structural design affects the grinding efficiency, and improper maintenance will reduce the efficiency.
Ball mill speed
According to the kinetic energy theorem, when the mass of an object is constant, the greater the speed of the object, the higher the energy it carries. Similarly, the greater the speed of the ball mill grinding jar, the greater the crushing and grinding energy carried by the particle media particles, and the better the crushing and grinding effect, but there may be problems such as increased energy consumption, increased loss of the particle media itself, and severe heating in the grinding jar; if the grinding jar speed is too low, the energy carried by the particle media may not be enough to achieve the crushing and grinding of the material, and it will not play a grinding role.
Filling rate of particle media
The filling rate refers to the ratio of the internal volume of the grinding jar occupied by the particle media in a loose state to the actual volume of the grinding jar. The filling rate of the particle media in the grinding jar is one of the key factors affecting the grinding efficiency.
Particle size of particle media
According to the impulse equation of the object, objects of different masses carry different kinetic energy at the same speed. In the particle media of the same material, the particle size determines the mass of a single particle. Therefore, choosing the appropriate particle size of the particle media can effectively improve the grinding efficiency.
Ball ratio
The ball ratio is the ratio of the material to the grinding medium, which also has a significant impact on the grinding efficiency. An appropriate ball ratio can ensure that the grinding medium effectively transfers energy to the material. The determination of the ball ratio needs to consider the material characteristics, mill type and expected grinding fineness.
Grinding water volume
During the wet grinding process, the grinding water volume has a direct impact on the grinding efficiency and slurry concentration. The fluidity of the slurry needs to be controlled by adjusting the water volume to ensure good interaction between the medium and the material, while avoiding overloading the mill and reducing the grinding efficiency.
Steel ball size and ratio
In the operation of the ball mill, the steel ball is the grinding medium, and its size and ratio have a decisive influence on the grinding efficiency. Appropriate steel ball size and ratio can effectively improve the grinding efficiency of the material, reduce energy consumption, and extend the service life of the mill.
Improvement of process and equipment
Another key means to improve the operation rate of ball mill is the improvement of process and equipment. With the continuous development of modern technology and the progress of materials science, traditional ball milling process and equipment are facing the necessity of upgrading and transformation.
Fault analysis and prevention
The operating efficiency and stability of the ball mill directly affect the quality and efficiency of the entire production process. However, in the long-term operation process, due to the influence of various internal and external factors, the ball mill often has various faults, such as high main bearing temperature, abnormal running sound, bulging belly and other problems, which will not only affect production efficiency, but also may cause equipment damage and increase production costs.
How does barium sulfate play an important role in battery production?
The main component of barite is barium sulfate (BaSO4), and its most well-known uses are oil drilling mud weighting agents, barium chemicals, and raw materials for nuclear radiation protection.
Barium sulfate has the advantages of strong chemical inertness, good stability, acid and alkali resistance, moderate hardness, high specific gravity, high whiteness, and the ability to absorb harmful rays. It is an environmentally friendly material. High-purity nano barium sulfate not only has the uses of ordinary barium sulfate, but also has other special uses. For example, it is widely used in industrial sectors such as coatings, papermaking, rubber, ink, and plastics.
Barium sulfate also has an important use - the most commonly used inorganic expander in battery manufacturing. As a basic, renewable and recyclable new energy, batteries are widely used in various fields such as transportation, communications, electricity, railways, national defense, computers and scientific research.
As a new energy mineral, barium sulfate plays a very important role in battery production. The main reason for the shortened battery life is: sulfation of the negative plate of the battery. Therefore, in lead-acid batteries, the main role of barium sulfate is to enhance the activity of the negative plate, prevent the plate from hardening, and extend the service life of the battery.
In the negative lead paste of the battery, precipitated barium sulfate with excellent filling properties and stable properties is generally used to reduce the degree of sulfation of the negative electrode of the battery. The reasons are as follows:
1. Barium sulfate and lead sulfate have the same lattice structure, which is conducive to the lead sulfate (PbSO_4) produced by the negative electrode of the battery with the help of barium sulfate (BaSO4) to be evenly distributed in various positions of the plate, thereby inhibiting irreversible sulfation and extending the life of the battery.
2. The precipitated barium sulfate has a small particle size and good dispersibility. Experiments have shown that in the absence of agglomeration, the smaller the particle size of barium sulfate, the lower the degree of sulfation of the negative electrode of the battery.
3. Precipitated barium sulfate is of high purity, contains almost no iron, and is not easy to discharge. When the battery is discharged, PbSO4 can have more crystal centers, better prevent the lead specific surface area from shrinking, enhance the activity of the negative electrode plate, prevent the plate from hardening, and extend the service life of the battery.
4. Barium sulfate is extremely inert and does not participate in the redox process of the electrode. It mechanically separates lead from lead or lead sulfate, thereby maintaining a well-developed specific surface area of the electrode material.