Superfine production process and modification process of silicon micropowder for copper clad laminate

Copper Clad Laminate (CCL for short) is an electronic basic material made by impregnating glass fiber cloth or other reinforcing materials with a resin matrix, covering one or both sides with copper foil and hot pressing. Used in communication equipment, consumer electronics, computers, automotive electronics, industrial control medical, aerospace and other fields. The choices of fillers for CCL include silica powder, aluminum hydroxide, magnesium hydroxide, talc powder, mica powder and other materials.

Silicon micropowder has relative advantages in heat resistance, mechanical properties, electrical properties and dispersibility in the resin system. It can be used to improve heat resistance and humidity resistance, thin CCL rigidity, dimensional stability, and drilling positioning accuracy The smoothness of the inner wall, the adhesion between the layers or the insulating layer and the copper foil, and the reduction of the thermal expansion coefficient.

Types of silicon powder for copper clad laminates

At present, the silicon powder used in integrated circuit copper clad laminates mainly includes five varieties: crystalline silicon powder, molten (amorphous) silicon powder, spherical silicon powder, composite silicon powder, and active silicon powder.

• Crystalline silica powder

Started early, the process is mature and simple, and the price is relatively cheap. It has a great effect on the improvement of the rigidity, thermal stability and water absorption of the copper clad laminate.

The impact on the resin system is not optimal, the dispersibility and sedimentation resistance are not as good as the molten spherical silicon powder, the impact resistance is not as good as the molten transparent silicon powder, the thermal expansion coefficient is high, and the hardness is large, and the processing is difficult.

• Fused silica powder

White color, high purity, low linear expansion coefficient, low stress, is mainly used in large-scale and ultra-large-scale integrated circuit molding compound, epoxy castable and potting compound, especially in the application of high-frequency copper clad laminates. .

The higher melting temperature requires higher production capacity of the enterprise, complicated process and higher production cost. Generally, the dielectric constant of the product is too high, which affects the signal transmission speed.

• Spherical silica powder

The fluidity is good, the filling rate in the resin is high, the internal stress is low, the size is stable, the thermal expansion coefficient is low after being made into the plate, and it has a high bulk density and uniform stress distribution, so it can increase the fluidity and Reduce viscosity.

The price is very high and the process is complicated. At present, it has not been used on a large scale in the copper clad laminate industry, and a small amount is used in the fields of integrated circuit carrier boards and printed circuit boards.

• Compound silicon powder

Good temperature resistance, good acid and alkali corrosion resistance, poor thermal conductivity, high insulation, low expansion, stable chemical properties; moderate hardness, easy to process, reduce the wear of the drill bit in the drilling process, and reduce the dust pollution during the drilling process .

If the performance of the copper clad laminate can be guaranteed, the cost needs to be reduced.

• Active silica powder

Good temperature resistance, good acid and alkali corrosion resistance, poor thermal conductivity, high insulation, low expansion, stable chemical properties, and high hardness.

The resin systems used by copper clad laminate manufacturers are not the same. It is difficult for the silicon powder manufacturers to make the same product suitable for all users' resin systems, and the copper clad laminate manufacturers are more willing to add modifiers themselves due to their habits.

Production process of ultra-fine silicon powder

As electronic products become lighter, thinner, shorter and smaller, the use of silicon micropowder filler in copper clad laminates also requires more and more ultra-fineness. The chemical synthesis method of ultra-fine silicon powder has low yield and complex process. The physical pulverization method has low cost, simple process, and is suitable for mass industrial production. The pulverization method is divided into a dry process and a wet process.

• Dry process

The process is feeding→grinding→classification→collection→packaging. The process is simple and the production cost is low. Generally, silicon powder production enterprises choose this process.

Grinding and classification equipment is the key. The grinding equipment mainly uses ball mills. The energy consumption of the ball mill is relatively low and the production capacity is large. For some products with higher purity requirements, the jet mill can be used because the jet mill does not introduce the grinding medium, but the energy consumption of the jet mill is relatively high. Low. The classification equipment is a general air flow classifier.

• Wet process

The process is feeding→grinding→drying→deaggregation→classification→collection→packaging. Drying and deaggregation processes are required. The process is complicated and the production cost is high. Fewer companies adopt this process. The cut point is less than 5 microns and requires a surface. This process is more suitable for processing products.

In fact, for the same process, the finer the particle size of the product, the lower the cut point, the higher the energy consumption, the lower the productivity, the more serious the equipment wear, the more obvious the increase in production costs, and the higher the cost.

Surface modification of ultra-fine silicon powder

The surface modification of ultra-fine silicon powder can reduce the interaction between particles, effectively prevent particle agglomeration, reduce the viscosity of the entire system, and increase the fluidity of the system; it can enhance the compatibility of the particles with the resin matrix and make the filler particles It can be evenly dispersed in the glue.

The key to surface modification lies in how to make the modifier uniformly dispersed on the surface of the particles while ensuring the chemical bonding conditions between the modifier and the particle surface.

The dry modification process is relatively simple and the production cost is relatively low, but the effect is relatively poor. The wet process has a better modification effect, but the process is complex, requires drying and depolymerization processes, and the production cost is high.

For conventional copper clad laminates with silicon powder, dry modification is generally recommended. For 8μm cut and 6μm cut comprehensive cost and performance considerations, dry process is recommended. For products with a cut of 5μm and below, a wet process is recommended. For finer products, gas phase synthesis has been used for surface modification.

With the continuous deepening of copper clad laminate manufacturers' understanding of silicon micropowder, new requirements are also put forward for the impurities of silicon micropowder. This is mainly because the silicon micropowder impurity affects the appearance, insulation and heat resistance of the PP and substrate of CCL. Come negatively. Silicon powder impurities can be divided into two categories: magnetic impurities and non-magnetic impurities according to whether they are magnetic or not.

The key to impurity control is to ensure that the raw material impurities are sufficiently low; to prevent the environment from being introduced during the production process; to prevent the equipment and pipes from wearing out; to remove impurities during the production process (using a magnetic separator to remove magnetic impurities, which is difficult to remove non-magnetic impurities).

The future trends of fillers for copper clad laminates are as follows:

• Functionalization: Low Dk, Low Df, high thermal conductivity, flame retardant, etc.
• High filling: High filling means better performance of inorganic fillers, including low CTE, low dielectric, and high thermal conductivity.
• Particle design: Interface and agglomeration issues require continuous improvement in surface treatment technology; spherical products are the choice for high-end applications.
• Particle size distribution design: In response to the thinning, the particle size needs to be continuously reduced, but it is also necessary to prevent the difficulty of dispersion.
• Impurity control: Ultra-thin, highly reliable, and highly thermally conductive substrates expect the impurity content of the filler to be as low as possible.

Article source: China Powder Network

by ALPA Powder

Types of grinding media balls

When the ball mill is working, it relies on the impact and grinding action of the medium on the material to complete the grinding of the material. In the mechanical process of the medium’s crushing of the material, the medium is used as the energy medium to convert the external energy into the crushing work of the material. And play a role in crushing the material.

Metal grinding media ball

Since the 1980s, chromium alloy cast iron grinding balls, multi-element low alloy cast iron grinding balls, various medium and high carbon low alloy waste heat quenched steel balls, bainite air-cold forging and rolling steel grinding balls, and multiphase matrix ductile iron grinding balls have been successively developed.

Non-metal grinding media ball

• Natural ball stone grinding media

The natural ball stone grinding media mainly refers to natural materials such as silica, sea pebbles and pebbles. In recent years, with the increasing depletion of high-grade natural ball stone and the rapid development of the ceramic industry, natural ball stone grinding media has been basically replaced by artificial grinding media.

• SiO₂ grinding media ball

There are two types of SiO₂ grinding balls: natural agate balls and glass balls made of quartz. Natural agate grinding balls are expensive and difficult to use in the ceramic production industry. They are only used in experiments and some special industries, and the amount is very small. The quartz glass balls used for grinding have low density, high abrasion, low grinding efficiency, and fragile. Except for the grinding of quartz powder and some special powders, no quartz glass is used for the grinding of other ceramic powders. Grind the ball.

• AI₂O₃ grinding media ball

AI₂O₃ grinding media ball is a ceramic ball with AI₂O₃ as the main component, also called AI₂O₃ ceramic ball. Because AI₂O₃ ceramic has excellent properties such as wear resistance, corrosion resistance, high temperature resistance, impact resistance, etc., AI₂O₃ ceramic balls are widely used in the raw materials of white cement, mineral processing, ceramics, electronic materials, magnetic materials, and coatings, paints and other industries. Grinding processing is a high-quality grinding medium.

• ZrSiO₄ grinding media ball

ZrSiO₄ grinding media balls are ZrSiO₄ ceramic balls prepared with ZrSiO₄ as the main raw material, and the mass fraction of ZrO₂ is about 65% to 68% or lower. ZrSiO₄ ceramic balls are mainly used for ultrafine grinding of ZrSiO₄ raw materials, which can increase the content of ZrSiO₄, but due to high abrasion and low strength, they lack a good market prospect. It is replaced by ZrO₂ grinding media with better performance.

• ZrO₂ grinding media ball

ZrO₂ grinding media ball refers to the ZrO₂ ceramic ball with stabilizer added and the ZrO₂ content reaches more than 90%. ZrO₂ ceramic ball has the following advantages and characteristics: it has a higher density and its impact force is large, so it has a higher grinding efficiency. Product contamination can be avoided. AI₂O₃, SiO₂ and metal grinding media will contaminate the product, while ZrO₂ is chemically inert to the dispersant. The surface is smooth and hard, it has excellent roundness and reasonable size distribution, and the wear of the medium itself and the grinding lining is very small during the grinding process. Has high fracture toughness, high strength, wear resistance and chipping resistance. It is suitable for wet grinding, dispersion of high-viscosity mud and running under high-speed operating conditions. Reduce the required grinding time, have higher production efficiency and lower production costs.

Article source: China Powder Network

by ALPA Powder

Modification process of kaolin

Kaolin, also known as porcelain stone, is a kind of clay and clay rock dominated by kaolinite clay minerals. It belongs to non-metallic minerals and is an aggregate of water-containing aluminosilicates composed of multiple minerals. The pure kaolin is white, fine, soft and soft, with good plasticity and fire resistance and other physical and chemical properties.

The structural units of kaolin are stacked in layers, mainly in the form of plates, which are easy to crack along the direction parallel to the layer, and are processed into ultra-fine powder. Kaolin exists in the form of scales in nature.

Because kaolin is prone to agglomeration when its specific surface area and surface energy are too high, it cannot be uniformly dispersed when filled with organic polymer materials such as rubber and plastic, which is not conducive to the improvement of product performance. Therefore, surface modification of kaolin is needed to reduce its surface energy. After surface modification, kaolin powder can achieve the effects of being hydrophobic, reducing surface energy, improving its dispersion and compatibility with polymer-based composite materials.

The physical properties of kaolin before and after modification

The surface modification of kaolin often uses surface chemical modification methods, so modifiers are added.

The surface modification process of kaolin generally has three methods: wet method, dry method and semi-dry method.

• Wet

The wet process requires pulping, dehydration, and drying processes, and the process is more complicated, especially dehydration filtration. If the particle size is less than 1250 mesh, it will be extremely difficult and complicated.

• Dry method

The dry modification process requires relatively high technology and equipment. The process completely eliminates the dehydration and drying link, and the process is simple.

• Semi-dry

While stirring the powder in the mixer, add an appropriate amount of water modifier and additives to mix in. After heating to a certain temperature and time, the product will be in a viscous state, and then slightly dried to obtain a modified product. The process omits the dehydration process and has higher production efficiency.

Commonly used modification methods of kaolin

• Calcined modification

In the calcining modification process, the reaction is carried out at a certain temperature, and the surface activation degree is different for different reaction times.

• Surface coating modification

Through surface coating, the stability of the material structure can be enhanced, the activity of the catalyst can be increased, the agglomeration of the powder can be prevented, and the dispersion characteristics and fluidity of the powder can be improved.

The main factors affecting surface coating modification are as follows:

The properties of kaolin: The specific surface area of kaolin determines the amount of surface modification. The larger the specific surface area, the more dosage required.

The properties of the modifier: From the perspective of dispersion, the adsorption of non-ionic substances on the surface of kaolin is relatively large, but the effect is not ideal; although the adsorption of negatively charged substances is not much, the dispersion is good.

Reaction conditions: Under different temperatures and pH values, the adsorption amount of coating ions on the surface of the powder is different, which will also affect the results of surface modification.

• Intercalation modification

Kaolin intercalation methods include mechanochemical method, microwave intercalation method, liquid intercalation method, and ultrasonic intercalation method.

Kaolin intercalation nanomaterials have better plasticity, whiteness, easy dispersibility, and adsorption properties, and can give the materials optical, electrical and magnetic properties, and expand the application range of kaolin clay. The intercalation method is currently the most promising and effective technology for preparing nano-kaolin. Commonly used chemical additives include: potassium acetate, dimethyl sulfoxide, urea, formamide, hydrazine hydrate and its extensions, etc.

Kaolin itself is a very versatile and important non-metallic mineral, which is widely used in more than a dozen industries such as petroleum, plastics, coatings, refractory materials, ceramics, and papermaking.

• Application of Modified Kaolin in Coatings

Kaolin is added to white paint or paint in an appropriate amount to enhance gloss and improve its covering ability.

• Application of modified kaolin in plastics

The application of modified calcined kaolin in plastic products can make the surface smooth, improve its dimensional accuracy, deformation temperature, impact strength, chemical resistance, etc., and increase the amount of filling and reduce the cost.

• Application of modified kaolin in rubber

Adding modified kaolin powder to the rubber can improve the physical and chemical properties of the product, greatly reduce the cost, improve the product level, and increase economic benefits.

Article source: China Powder Network

by ALPA Powder

Preparation technology of barite powder

Barite is the most common mineral. Its composition is barium sulfate ( BaSO₄ ), which can be produced in low-temperature hydrothermal veins and sedimentary rocks. The chemical composition includes 65.7% BaO and 34.3% SO₃ , and there are similar substitutions of Sr, Pb and Ca in the composition. Barite is usually plate-like, granular, fibrous aggregates and crystal clusters of plate-like crystals, a few of which are dense, massive, cryptocrystalline, and soil-like, and stalactites and nodules with concentric belt-like structures are also seen. .

The pure barite is colorless and transparent, generally white, gray, light yellow, light brown, and may be light blue, pink, dark gray, etc. with impurities. Glass luster, transparent to translucent, low abrasion, good shielding, can absorb X-rays and Y-rays, chemically stable, and pure ones are hard to dissolve in water and acid.

The world is rich in barite resources, with reserves of 2 billion tons. World-famous barite producing areas include: Westmanland and Cumbria in the United Kingdom, Phils Bonny in Romania, Saxony in Germany, Tianzhu in Guizhou, China, Gongxi in Hunan, Liulin in Hubei, and Guangxi Heifenggou in Gansu, Xiangzhou, Shuiping in Shaanxi, etc.

Barite is divided into high-purity barite, ultra-fine barite, and ultra-fine active barite.

Preparation technology of high-purity barite powder

• Physical purification

Hand selection: According to the difference in color and density of barite and associated minerals, select blocky barite.

Gravity separation: According to the density difference between barite and associated minerals, the raw ore is screened, crushed, grading desliming, jigging, shaking table and other processes to obtain products with a grade of more than 88%.

Magnetic separation: It is often used to remove some iron oxide magnetic minerals and use it as the raw material of barite for collar-based drugs that require very low iron content.

• Chemical purification and whitening

Flotation: Barite with a small particle size is embedded, and physical removal of impurities is not good, and flotation is often used.

Chemical purification and whitening: through acid (or alkali) leaching, oxidation-reduction to remove carbon and iron, manganese, magnesium, nickel and other impurities in the ore.

Calcining and whitening: The hydrothermal barite undergoes heat absorption and blasting at high temperatures to volatilize the color-causing organic matter distributed in the barite crystals or gaps.

Preparation technology of ultra-fine barite powder

• Dry process

Jaw crusher, Raymond mill air classifier → baking oven → washing → dilute pickling → pulping → reaction kettle pickling reduction → filter press → washing → filter press → drying → crushing → packaging → product

• Wet process

Stirring mill, vibration mill, ball mill→modifier or precipitant→hydroxide or hydrated oxide→coating film→washing→drying→roasting→fixing→product

Preparation technology of ultrafine active barite powder

Surface chemical coating: modifier molecules are covered on the surface to obtain modified products.

Mechanochemical modification: Activate the particle surface, improve the activity of BaSO₄ and other organic matter.

Encapsulation modification: The surface of the particles is covered with a homogeneous film with a certain thickness.

High-energy modification and acid-mechanical modification: use ultraviolet, infrared, corona discharge and plasma irradiation for surface treatment.

Application of barite powder

• Chemical raw materials

Reagents and catalysts, medicaments for mineral processing and paper production, additives for oils and fats, production of plastics, pesticides, herbicides, fungicides, production of various fireworks...

• Drilling mud

Barite is usually relatively pure, soft, relatively dense, chemically friendly, and inexpensive. 80-90% of its output is used as a weighting agent for drilling mud.

• Glass material

Barite is used in glass production to make the melt uniform and improve the brightness and transparency of the glass product.

• Chemical packing

Barite powder is a general industrial filler and a good brightening agent and weighting agent. Chemically bleached barite powder is a good white pigment.

• Other applications

Barite has good properties of absorbing Y radiation, so it can be used as a shielding material; it can also be used as a getter binder for vacuum tubes such as televisions.

The development trend of barite powder preparation technology

The main preparation technologies of barite-based mineral materials include ultra-fine and surface modification, but there are not many in-depth studies on the theoretical issues of barite ultra-fine processing, mechanochemistry, interface chemistry, doping modification and other processes. Traditional barite minerals are mainly used in low value-added fields such as petrochemicals, with low product utilization and low value.

We must transfer the traditional application of barite to how to combine the mineral composition, chemical composition structure, surface properties and other related characteristics, develop simple modification processes, study relatively inexpensive, non-toxic surface modifiers, and promote The development of barite processing, the comprehensive utilization of barite, and the improvement of the competitiveness of barite ore powder.

Article source: China Powder Network

by ALPA Powder

Production and modification process of heavy calcium carbonate

Heavy calcium carbonate, also known as ground calcium carbonate, or heavy calcium for short, is made by processing natural carbonate minerals as raw materials. It has high chemical purity, high inertness, good thermal stability, will not decompose below 400℃, high whiteness, low oil absorption, low refractive index, soft, dry, free of crystal water, low hardness, low abrasion value, non-toxic , Tasteless, odorless, good dispersion and other advantages.

As a functional inorganic filler, calcium carbonate is mainly used in papermaking, plastics, paint and coatings, rubber and other industries. From a global perspective, calcium carbonate for papermaking accounts for 60% of the consumption structure.

As a functional filler, heavy calcium carbonate, its mesh number, whiteness and calcium carbonate content determine its application areas. 325 mesh, whiteness 95%, calcium carbonate content 98% can be used for paper making; 325 mesh, whiteness 95%, calcium carbonate content 98.5% can be used for artificial marble; 325 mesh, whiteness 90%, calcium carbonate content 98% Can be used for construction; 400 mesh, whiteness 93%, 96% calcium carbonate content can be used for rubber; 400 mesh, whiteness 95%, calcium carbonate content 99% can be used for plastics; 400 mesh, whiteness 95%, carbonic acid 98.5% calcium content can be used for floor tiles.

With the development of grinding and grading equipment, the production and demand of ultrafine heavy calcium powder has increased significantly. Among them, the use of 2500-6500 mesh heavy calcium powder in high-end papermaking has also increased.

Production of heavy calcium carbonate

The raw materials are carbonate minerals such as shells, calcite, marble, limestone, chalk and dolomite.

Common heavy calcium processing methods include dry, wet, and dry-wet process combination methods. Dry processing is conducive to the realization of industrial scale and a certain degree of product refinement; wet processing is conducive to achieving a higher degree of product refinement and functional production; dry and wet process combination is conducive to making up for the dry process in high-end products The insufficiency.

From a practical point of view, products with D97=2500 mesh or less are generally produced by dry method; products with D97=2500~6500 mesh (or higher content of 2μm) are usually produced by wet method.

• Dry process

The main equipment of dry process is Raymond mill, ball mill, jet mill, ring roller mill, vibration mill, vertical mill, and high-speed mechanical impact mill.

At present, the dry processing of large-scale enterprises in the world mostly uses vertical mill processing equipment and technology. The large-scale and fine-grained benefits of vertical mill dry powder production are the most obvious. It has become one of the main research directions in the refined processing technology of heavy calcium powder in recent years.

• Wet process

The wet method is used to process refined and functional heavy calcium powder, the mesh number is above 3000, and the equipment mostly uses stirring mills. Adding pulverizing aids in the fine media mill can prepare sub-micron or even nano ultra-fine powder.

Wet grinding mainly produces products above 3000 mesh, and dry grinding mainly produces products below 2500 mesh. The particle size distribution of heavy calcium produced by wet method is narrow, which is unimodal or bimodal; the particle size distribution of heavy calcium produced by dry method is broad, and the distribution is bimodal or multimodal.

The particles of wet grinding products are generally spherical or quasi-spherical; dry products are mostly indeterminate and have obvious edges and corners.

• Dry and wet process combination

The dry-wet integrated process of vertical mill + secondary classification + tertiary classification and multi-stage wet grinding can be used to produce 325~800 mesh products to meet the basic needs of the market, and use super-subdivision equipment for secondary and tertiary The graded production of medium and high-end fine powders of 800 to 2500 meshes meets the needs of the medium and high-end markets. The lower product adopts wet grinding and other fine grinding and functional development, and produces 2500~6500 mesh ultra-fine functional powder to meet the high-end market demand.

The dry-wet integrated process of vertical mill + secondary classification + tertiary classification combined with multi-stage wet grinding not only realizes the large-scale industrialization of heavy calcium, refined and functional products, but also improves the product structure, which is the future of heavy carbonic acid An integrated demonstration process for the in-depth development of calcium industry transformation and upgrading.

Modification of heavy calcium carbonate

The minerals of heavy calcium carbonate dissociate during the crushing process, and unsaturated particles Ca²⁺ and CO₃^2- will be exposed. Unsaturated particles will hydrate with surface water, making the surface of heavy calcium carbonate particles hydrophilic and oleophobic. The active points on the surface of heavy calcium carbonate can be used for physical and chemical modification to change its hydrophilic and oleophobic properties.

Modification methods include: physical coating modification, surface deposition modification, surface chemical modification (coupling agent modification, composite coupling agent modification, polymer coating modification, organic matter modification), mechanochemical modification High-energy surface modification (irradiation, plasma, ultrasonic).

Optimize the effect of surface modification, the size of modified heavy calcium carbonate is nano-sized, green and environmentally friendly, and the conversion of calcium carbonate modification to special type, functional type and high value-added type is the development trend of heavy calcium surface modification.

Article source: China Powder Network

by ALPA Powder

Production Technology and Application of Silicon Micropowder

Silicon powder is made of natural quartz (SiO2) or fused quartz (amorphous SiO2 after high temperature melting and cooling of natural quartz), which is crushed, ball milled (or vibration, jet mill), flotation, pickling purification, high-purity water treatment, etc. The micro powder processed by this technology.

Silicon powder is gray or off-white powder, non-toxic, odorless, non-polluting, resistant to temperature, acid and alkali corrosion, poor thermal conductivity, high insulation, high hardness, low swelling, and stable chemical properties. According to the production process, it can be divided into crystalline silicon powder, fused silicon powder, cristobalite silicon powder, and active silicon powder. According to the level, it can be divided into ordinary silicon powder, electrical grade silicon powder, electronic grade silicon powder, fused silicon powder, ultrafine silicon powder, and "spherical" silicon powder. According to the purpose, it can be divided into silicon powder for paint and coating, silicon powder for epoxy floor, silicon powder for rubber, silicon powder for sealant, silicon powder for electronic and electrical plastic packaging materials, and silicon powder for precision ceramics.

Production process of silicon powder

• The beneficiation and purification of silicon powder raw materials

Mineral beneficiation and purification generally involves crushing, sieving and grinding siliceous raw materials with high impurity content to fully dissociate silica and impurities. In actual production, purification is carried out according to the required quality. Either through flotation, magnetic separation to remove impurities, or through water washing and grading to remove impurities, or pickling to remove impurities, and after drying, it is used as the raw material for silicon micropowder.

• Production process of silicon powder

1. Production process of angular silicon powder

Angular silicon micropowder is an irregularly angular silicon micropowder obtained by grinding the raw material of silicon micropowder. The main production equipment of angular silicon powder includes ball mill, powder classifier, vibration mill, and dryer.

2. Production process of spherical silicon powder

Spherical silicon powder is a kind of high-strength, high-hardness, and emotional spherical particles made of high-quality raw quartz ore and processed by a unique process. The production processes of spherical silicon micropowder abroad include high-temperature melting spray method, gas flame method, hydrolysis method of silicon tetroxide, etc., and control ethyl orthosilicate in the liquid phase. The main production equipment includes a powder quantitative conveying system, a gas volume control and mixing device, a gas fuel high temperature flame spray gun, and a cooling recovery device.

3. Recovery method of silicon micropowder recovery process

Pulse jet bag dust removal, anti-adhesive big bag dust removal, and electric dust removal.

Application of silicon powder

• Application fields of general silicon powder products

Ceramics, metallurgical flux, casting and metal surface treatment, electronic component packaging, rubber, high-grade paint, anti-corrosion coatings, welding rod coating, construction mortar and high-strength concrete aggregates, high-grade refractory materials, solar photovoltaic cells, military antenna reflectors, teeth Use materials, environmental protection and oil wells to pressurize.

• Application fields of fused silica powder products

Fused silicon powder has the characteristics of high purity, excellent electrical properties, high hardness, wear resistance, stable chemical properties, and good whiteness. It is often used in plastic packaging materials for ultra-large-scale integrated circuits, epoxy castables, potting materials, and other chemical fields.

• Application fields of spherical silica powder products

Low oil absorption, mixed viscosity and friction coefficient, easy to disperse, uniform mixing, can significantly increase the fluidity of materials, commonly used in VLSI plastic packaging materials, VLSI, fine chemicals, rewritable CDs and large areas Electronic substrates, special ceramics and special rubber, aviation, aerospace engineering, etc.

With the development of the high-tech industry, silicon micro-powder has become more widely used and used more and more, which has great market demand and potential. The rapid development of the microelectronics industry has put forward higher and higher requirements for silicon micropowder. Silicon micropowder not only needs to be ultra-fine, high-purity, and low-radioactive element content, but also spheroidizes the particle shape. For the huge market demand in the future, it is necessary to improve the quality of silicon raw materials, improve the technical level of silicon powder production, and strengthen the testing and control of the production process, so as to improve the quality of silicon powder products.

Article source: China Powder Network

by ALPA Powder

Flake graphite regrind process and equipment

Among graphite products, flake graphite is the most widely used and in demand, and its value is proportional to the size and grade of the flakes. However, the traditional flake graphite grinding and floating process generally damages the graphite flakes greatly. Therefore, for flake graphite ore with different embedded particle sizes, it is of great significance to select the regrind process and equipment reasonably.

Crystalline graphite, also known as flake graphite, has a series of excellent physical and chemical properties such as electrical conductivity, thermal conductivity, high temperature resistance, plasticity, lubricity, and chemical inertness. It is widely used in metallurgy, machinery, electrical, light industry, chemical industry, textile, and national defense. It is one of the non-metallic materials indispensable for global high-tech development.

Usually large flakes refer to flake graphite of +50 mesh, +80 mesh, and +100 mesh, and flake graphite below these particle sizes is called fine flake graphite.

The size of the scale and its fixed carbon content are the most important reference indicators for judging the value of graphite flakes, and the dissociation method and degree are the most important factors that determine the yield of large scales and the fixed carbon content in concentrate products. Therefore, for the optimization of flake graphite beneficiation process, we must first start from the grinding process.

In recent years, breakthroughs have been made in grinding technology, and many new technological processes have emerged, such as: graded grinding and flotation, rapid flotation technology, stage grinding and stage separation, pre-separation, collector-free flotation, and shear flocculation. Flotation process, ultrasonic strengthening process.

Flake graphite regrind equipment

Research has found that the sorting process and sorting equipment will not physically destroy the graphite flake structure, only the large flake graphite will be damaged and lost during the regrinding process. Therefore, the most critical technology for graphite beneficiation is the reasonable selection of regrinding equipment.

The most important and core part of protecting graphite flakes is the selection of regrind equipment.

• Ball mill

The ball mill is a grinding equipment with a wide range of applications, a long history, simple operation, and low production cost in the beneficiation plant. Lattice type ball mills and overflow type ball mills are widely used.

In the graphite regrinding process, the ball mill is mainly used for one-stage grinding or two-stage regrinding. The installed power is generally 80~120kW, the medium filling rate is 30%~40%, and the single processing capacity is 10~40t/h. Etc.

• Mixing mill

The biggest difference between the stirring mill and the ball mill is that the former has a stirring device inside. The stirring mill drives the grinding medium to rotate and revolve through the rotation of the stirring device, and then generates shear, impact, and friction effects to achieve the purpose of fine grinding of the material.

The common stirring device forms of agitating mills include spiral, disc, rod and impeller. In the graphite regrinding process, there are two types of impeller and rod, which are more widely used or have broad prospects. It is a double-layer impeller type and a multi-layer impeller type, which are used in graphite regrinding processes in many areas in China.

• Rod Mixing Mill

The rod-type stirring mill is a fluidized vertical stirring mill, which uses the rotating kinetic energy of the stirring rod to produce high-energy motions of the medium and slurry mixture in the grinding chamber, thereby generating shear, friction and The squeezing force forms an ideal grinding environment for fine grinding, regrinding and scrubbing.

The installed power of the rod-type stirring mill is generally 18.5~1100kW, but the application specifications in the graphite regrinding process are generally small, generally 18.5~185 kW, the grinding medium is ceramic balls, and the processing capacity of a single device is generally 1.5~ 15 t/h.

• Disc grinder

Starting from the research on the grinding characteristics of flake graphite, the regrind equipment is a disc mill. After the graphite flakes are ground under the action of the rotating thrust of the grinding disc, the scales are dissociated under the action of the grinding force along the crystal layer.

The shortcomings such as fast wear, large maintenance workload, strict requirements on the concentration of ore pulp and small processing capacity, have led to fewer applications in the graphite industry.

• Sand mill

Grinding medium and graphite pulp move both axially and radially in the sand mill. Due to the differential speed, they perform rotational friction with each other to form a peeling force, which separates the graphite from the gangues on it, and thus separates the graphite from the gangue. Body dissociation.

The protective effect of graphite flakes is average. Moreover, the equipment has certain shortcomings. For example, due to the high stirring speed during operation, the life of the equipment cylinder is short, and the replacement frequency in production is high, which directly affects the production efficiency.

• Vibration mill

Vibration mill is a kind of high-efficiency grinding equipment. As long as the amplitude is well controlled, using it as a regrinding equipment for graphite is beneficial to the protection of Dalin tablets.

Vibration mill is a dry grinding equipment, and graphite is in the form of slurry after flotation, and it must be dried before vibrating mill regrind, so it is difficult to realize in graphite production; and vibration mill has high noise and requires high infrastructure .

In the selection of grinding media, the use of rods, columns and cylinder rods to protect large scales is better than ball media. In the selection of mills, the use of disc mills, sand mills, vibration mills, vertical mixing mills, rod mills and other regrinding equipment with a grinding and stripping effect has obvious effects on the protection of large scales.

Because of the large processing capacity of the first and second stage grinding, the ball mill can be selected as the grinding equipment, but it must be noted that the ball mill is destructive to the large flake graphite and the grinding efficiency is low. Therefore, if the economic cost allows, consider using a large-size rod-type agitating mill to replace the ball mill for one or two stages of fine grinding.

For the regrind after the second stage, due to the moderate processing capacity, impeller and rod agitating mills can be selected as regrinding equipment. This type of equipment has the advantages of low power consumption, high efficiency, low consumption of grinding media, strong applicability, stronger production capacity, safer operation, and easy implementation of conventional and optimized control, especially the rod-type stirring mill, which is suitable for large The protection of flake graphite is more effective.

Article source: China Powder Network

by ALPA Powder

Application of inorganic powder in plastics

Plastic is everywhere in life, and powder is everywhere in plastic.

Powder materials for plastics include inorganic powders and carbon-containing powders.

Inorganic powder is divided into industrial waste residue and non-mineral powder. Industrial wastes include red mud, white mud, fly ash beads (glass beads), etc.; non-mineral powders are divided into heavy calcium, talc, kaolin, wollastonite, mica powder, brucite powder, which are crushed and classified , Barite powder, etc., light calcium (including nano-calcium carbonate), aluminum hydroxide, magnesium hydroxide, precipitated barium sulfate, etc. formed by chemical reaction.

Carbon-containing powder is divided into carbon and carbon oxide powder. Carbon includes carbon black, graphite, etc.; carbon oxide powder includes wood powder, straw powder, nutshell powder, starch, etc.

The role of traditional inorganic powder in plastics

• The modification effect of calcium carbonate on plastics

Mechanical properties: improve the rigidity and hardness of plastic products, improve tensile and flexural strength, and significantly increase the modulus of elasticity; thermal properties: the coefficient of thermal expansion and shrinkage are reduced in all aspects, and the warpage and curvature of the product become smaller. The deformation temperature increases with the increase of the filler, and the radiation performance: the filler has a certain absorption capacity for radiation, which can prevent the aging of plastic products.

• The modification effect of wollastonite on plastics

It has good insulation, wear resistance, and high refractive index; it can improve impact strength, enhance fluidity, and improve tensile strength and mold shrinkage; it can significantly reduce the water absorption of the material.

• Modification effect of talcum powder on plastics

It can improve the tensile strength, impact performance, creep resistance, heat resistance, tear resistance of plastic products, improve the surface appearance of the product, reduce the shrinkage of the product, improve the barrier effect, reduce the air permeability, and increase the rigidity of the plastic product And crispness.

In addition to the above inorganic powder fillers, steel sulfate can improve the chemical resistance, heat resistance, and appearance of plastic products. Mica powder can reduce the shrinkage, warpage, curvature and specific gravity of the product, and improve the product. The mechanical properties of the product increase the surface gloss and weather resistance of the product.

Comparison of application performance of different inorganic powders in plastics

Performance comparison of different materials filled in nylon 66

Comparison of properties of polypropylene filled with different materials

Several factors affecting the application of inorganic powder in plastics

• Surface modification and activation of inorganic powder

The compatibility of inorganic powder fillers with polymers is relatively poor. If added directly, inorganic powders cannot be uniformly dispersed in the polymer, and its surface modification and activation are very important. Activation rate + fastness = modification effect.

• Moisture and volatile matter in inorganic fractions

Moisture and volatile matter will form gas due to high temperature, friction and other factors during plastic processing. After cooling, it will cause irregular cracks in plastic products, and may also cause secondary agglomeration of dried fine powder. In actual production and application, when the moisture and volatile matter are at 20.3%, it will affect the plastic processing and product quality.

• Static electricity

Inorganic powder with flaky structure is easy to rub and generate static electricity in the middle of processing, which makes small particles agglomerate and affects the dispersion effect of the product.

What are the new applications of inorganic powders

• Kaolin

Improve the tensile strength and modulus of low-plasticity plastics with a lower glass transition temperature; refer to the rigidity and strength of high products; increase the electrical insulation strength of the plastic after burning, and be used for high-voltage insulation products.

• Wood flour, bamboo flour, straw flour

Rich sources, low prices, low-carbon and environmentally friendly; heat resistance is the main bottle precondition that restricts dosage and use.

• Fly ash

The specific gravity is small, the hardness is large, and the fluidity is good; the fly ash is processed into a new material with a certain particle size and has adsorption performance, which can effectively adsorb harmful substances, odors and moisture.

• Calcium silicate

Small specific gravity, strong odor adsorption, excellent physical properties; mainly used in waste plastic processing, plates, pipes, etc.

• Electric lime

The main discharge of chemical products is solid waste; it is mainly used in plastic materials.

• Black talc, black calcite

It can partially replace carbon black.

Six major trends in the development of inorganic powders

Harmless production and application, industrial extension, miniaturization of processing and application, scientific value, diversification of application, and high-performance products.

Inorganic powder is a new functional modified material with abundant resources, low price and excellent performance. However, we should strive to abandon the traditional cognition that inorganic powder is a low-value filler material. Significant technological breakthroughs should be made in low carbon and other aspects. Inorganic powders should develop in the direction of functionalization, greening, and miniaturization, so that low-value-added filler materials will be fully transformed into high-end functional modified materials.

Article source: China Powder Network

by ALPA Powder

High-purity ultra-fine electronic grade quartz powder

In semiconductor integrated circuit packaging, packaging materials can play a role in semiconductor chip support, chip protection, chip heat dissipation, chip insulation, and interconnection of the chip with external circuits and optical paths. In electronic packaging materials, filler occupies a larger share. The high-purity ultra-fine quartz powder used as a filler for packaging materials has incomparable advantages.

Quartz powder requirements for electronic packaging

• High purity and ultrafine

Traditional application areas of quartz powder

High-purity ultra-fine quartz powder can improve the acid and heat performance, mechanical strength, dielectric properties and thermal conductivity of the packaging material; reduce the thermal expansion coefficient, water absorption rate, molding shrinkage rate and cost rate of the packaging material. High-purity ultra-fine quartz powder is widely used in the manufacture of electronic inks, optical fibers, advanced precision ceramics, precision grinding of optical devices and electronic components, etc. The most important of which is in the field of electronic packaging. Quartz powder for electronic packaging must be high-purity and ultra-fine. Generally, the purity of SiO2 is required to be above 99.99%, Fe2O3 is less than 5ppm, and the total amount of impurities is required to be less than 300ppm.

• Spheroidization

With the rapid development of the microelectronics industry, large-scale and ultra-large-scale integrated circuits have increasingly higher requirements for packing materials for packaging materials. Not only ultra-fine and high-purity, but also low radioactive element content is required, especially for particle shapes. Sphericalization requirements.

High-purity ultra-fine spherical quartz powder has the properties of low friction coefficient, low impurity, low stress, low expansion, high dielectric, high heat resistance, high humidity resistance, and high filling.

The surface area of ​​the ball is the smallest, the isotropy is good, it is uniformly mixed with the resin to form a film, the amount of resin added is small, and the fluidity is the best. The higher the quartz powder filling rate, the smaller the thermal expansion coefficient of the molding compound, and the lower the thermal conductivity, the closer the thermal expansion coefficient of monocrystalline silicon is, and the better the performance of the electronic components produced therefrom.

The plastic molding compound made of spherical powder has the smallest stress concentration and the highest strength. When the stress concentration of the angular powder molding compound is 1, the stress of the spherical powder is only 0.6. Therefore, the spherical powder molding compound has a high yield when encapsulating integrated circuit chips. It is not easy to cause mechanical damage during transportation, installation and use.

The friction coefficient of spherical powder is small, and the wear on the mold is small, so that the service life of the mold is long. Can reduce costs and improve economic efficiency.

Preparation of High Purity Superfine Electronic Grade Spherical Quartz Powder

Experts show that as long as the purity can meet the requirements, it is best to use natural crystalline quartz as the raw material, with low cost and simpler process lines. Quartz raw materials include quartzite, vein quartz, quartz sandstone, powder quartz, and quartz sand.

Natural quartz minerals contain a large number of inclusions and cracks. The use of ultrafine pulverization technology can greatly reduce the number of cracks and defects. Combined with the purification process, the content of harmful impurities can be better reduced.

Thermal crushing first can greatly improve crushing efficiency, reduce equipment failure rate, and reduce crushing costs.

The requirement for grinding media is to choose less abrasion, high hardness, and a diameter between 1~5mm.

For ultrafine quartz powder, stirring mill, vibrating mill, and jet mill are often used.

• Processing technology

Quartz powder → magnetic separation → flotation → ultra-fine grinding → pickling → deacidification cleaning → filter press dehydration → drying → breaking up → finished product

The advantages of dry production of quartz powder are obvious: low comprehensive production cost, high output, and easy control of the process. However, the dust is too large and there is a crushing limit, it is difficult to produce micron-sized quartz powder. Therefore, the wet process is generally used when producing high-purity ultra-fine spherical quartz powder powder.

• Purification process

1.  Physical purification

Water washing and grading desliming, scrubbing, magnetic separation and flotation. But in order to obtain high-purity quartz powder, the quartz powder must be chemically purified.

2. Chemical purification

Acid leaching: The principle is to use the insoluble acid, but the impurities can be dissolved in the acid, and the impurities in the quartz powder are removed by acid leaching to achieve the purpose of purification. Commonly used acids are hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid and oxalic acid.

• Sphericalization process

The research of China's high-purity ultra-fine spherical quartz powder has entered the pilot stage, and has undergone three adjustments: AC high-frequency plasma fusion method, DC plasma fusion method, and arc method formed by carbon electrodes. The key to the technology is that the heating device requires a stable temperature field, an easy-to-adjust temperature range, and a clean heat source environment that will not cause secondary pollution to the quartz powder. There is currently no report on the industrialized production system.

Other commonly used silica high-temperature fusion spraying method, gas flame method, liquid phase control ethyl orthosilicate, silicon tetroxide hydrolysis method.

Status analysis and outlook

With the further development of the electronics industry, the fourth wave of development of electronic packaging technology is bound to usher in the system-in-package, which will lead to the sudden emergence of the spherical quartz powder market.

With the advancement of science and technology, especially the development of microelectronics technology, the demand for high-purity and ultra-fine electronic grade quartz powder has doubled, and its quality requirements have become higher and higher. Actively explore and promote the progress of quartz beneficiation and purification technology, and realize the low-cost, large-scale industrial production of refined quartz, high-purity and ultra-high-purity quartz, which is important for making up for the shortage of natural crystal resources and meeting the demand for high-purity ultra-fine quartz powder for high-tech use. The practical significance of.

Article source: China Powder Network

by ALPA Powder

Ultrafine talc grinding production line

Talc is generally lump, leaf, fibrous or radial, and the color is white, off-white, and it will have various colors due to other impurities. Talc is finally applied in powder form. Therefore, fine grinding and ultra-fine grinding are necessary processing techniques for talc. Superfine talcum powder is one of the most used ultrafine powder products in the world today. It is widely used in papermaking, plastics, rubber, paints, cosmetics, ceramics, etc.

At present, the processing of ultrafine talc powder mainly adopts the dry process. Although wet grinding has been studied, it is rarely used in industry.

Jet milling process

Raw material → feeding → crushing (hammer crusher → bucket elevator → vibrating feeder) → drying (vertical dryer) → medium crushing (hammer crusher) → fine grinding (Raymond mill) → superfine grinding (the jet mills used in industry include disc jet mills, fluidized bed counter-jet jet mills, circulating tube jet mills, etc.)→finished products

Talc has a Mohs hardness of 1, which is naturally crushable and has good grindability. For the fine grinding of talc, various types of Raymond mills are generally used, mainly producing 200 mesh and 325 mesh products. However, if fine grading equipment is installed, products with 500 to 1250 meshes can also be produced.

Dry production equipment mainly includes high-speed mechanical impact mills, jet mills, centrifugal self-mills, rotary mills, vibration mills, stirring mills, and tower mills. In addition to jet mills, in order to meet the requirements of user particle size distribution, other classification equipment generally needs to be equipped with fine classification equipment. Commonly used fine classification equipment is various turbo-type air centrifugal classifiers.

High-speed mechanical impact superfine grinding process

Raw material→crushing (hammer crusher, crushing to 8mm is enough)→mechanical impact superfine grinder→turbine type fine classifier (the coarse-grained product after classification can be returned to the mill or can be used as a separate product) →Finished product

The centrifugal self-grinding and rotary mill superfine grinding process of talc is generally similar to the high-speed mechanical impact superfine grinding process.

Acceptance standard for talcum powder entering the factory

Talc powder should be stored in a dry warehouse. It can be used for paper fillers and resins, stickies adsorbents, 600 mesh talcum powder is used for newsprint systems, high-end food packaging base paper (without fluorescence), and 325 mesh talcum powder is used for DIP pulping. , Low-grade food packaging base paper (no fluorescence).

Article source: China Powder Network

by ALPA Powder