What is the difference between silicon micro-powder and microsilica?

- Jun 09, 2018 -

                                        What is the difference between Silicon Micropowder and microsilica ?

With the continuous deepening of foreign understanding of Silicon Micropowder and microsilica , Silicon Micropowder and microsilica have been widely used. 

Its commercial advantages and extensive market space have been well known. However, at present, most of the domestic manufacturers of Silicon Micropowder and microsilica confuse the concept of the two, and only consider the two as a product in literal terms. 

In fact, there is a big difference between silicon micro-powder and microsilica. If the difference is not clear, it will easily lead to trade negotiation mistakes and the market price of microsilica/silica fume will be confusing. 

The author now does a detailed analysis of the current situation of the two markets, production process, appearance, performance, purpose, indicators and other aspects. 

I. Market Status of Silicon Micropowder and Microsilica  At present, only a few countries in the world, such as China, the United States, and Germany, have silicon micron powder production capacity. The market for China's silicon micropowder is mainly domestic, and the volume of exports is relatively small. 

The acceleration of the solar energy industry has driven the market demand for silicon micropowder to grow rapidly, and silicon micropowders have been in short supply. According to relevant data, there are more than 170 manufacturers of silicon micropowder for domestic production of solar photovoltaic converters, of which about 40 are in Shanghai. Therefore, silicon micropowders have great market demand and potential in the country. 

The market of micro-silica fume is mostly concentrated in foreign countries. The research on micro-silica fume has been abroad for several decades. The research and system of micro-silica fume is comparatively systematic. Many countries have established corresponding research institutions and established corresponding production plants. In the United States, the use of micro-silica fume in a project to repair the Zizuba Dam stilling pool saved tens of millions of dollars in 1983. The micro-silica fume also belongs to an extensive industrial by-product in China. 

In the past, most companies did not pay enough attention to the recovery of micro-silica fume. Most of the silicon content of the micro-silicon fume that was not recovered or recovered could not reach the standard, and the value and benefits thereof were not fully reflected. The market still needs further development. With the strengthening of the country's environmental protection efforts, while forcing silicon-iron alloys and industrial silicon manufacturers to install environmentally-friendly dust removal equipment, they have introduced policies to curb excessive development of high-energy-consuming industries, and the resources of microsilica will become more and more abundant. Therefore, in the face of the cancellation of related preferential policies, each ferroalloy manufacturer should actively look for the benefits of the microsilica market brought about by the recovery of dust, and choose an economical dust removal equipment that integrates environmental dust removal and dust recovery. 

2.the difference between the silicon powder and microsilica in the production process The silicon micropowder is made of natural quartz (SiO2) or fused silica (natural quartz is melted at high temperature, cooled amorphous SiO2) by crushing, ball milling (or vibration, airflow) Milling), flotation, pickling, high-purity water processing and other multi-process processing of the powder. Microsilica, also known as silica fume, condensed silica fume, silica fume. 

When ferroalloys are used for the smelting of ferrosilicon and industrial silicon (silicon metal), a large amount of highly volatile SiO2 and Si gases are generated in the ore furnace, and the gas is discharged and quickly oxidized to condense and precipitate. It is a by-product of large-scale industrial smelting. The entire process needs to be recycled with environmentally friendly dust removal equipment. Because of its lighter weight, it needs to be encrypted with encryption equipment. In the actual transaction process, many manufacturers regard silicon micropowder as microsilica, but because of the essential difference between the two, there are often deviations in the transaction process, making the product indicators provided by the manufacturers and the demand-side index parameters exist. Huge difference. 

3.the difference between the appearance of silicon powder and micro-silica powder From the appearance of silicon powder and micro-silica powder is also relatively easy to identify the basic. Silica micropowder is pure, white and balanced, and it is a non-toxic, odorless, non-polluting inorganic non-metallic material. According to different silica raw materials, reducing agents or furnace conditions, most of the microsilica are gray or dark gray. . 

During the formation process, due to surface tension during the process of phase transformation, non-crystalline amorphous spherical particles are formed, and the surface is relatively smooth, and some are agglomerates with multiple spherical particles stuck together. White microsilica is rare and the number is relatively limited. IV. Differences in properties and uses of silicon microsilica and microsilica From the viewpoint of the performance or role of silicon microsilica and microsilica: Silica micropowder has good temperature resistance, acid and alkali resistance, poor thermal conductivity, high insulation, low expansion, and chemical properties. Stable performance, hardness and other excellent performance. According to its use of silicon powder is divided into the following categories: 

1), ordinary silicon powder, mainly used in epoxy resin casting materials, potting materials, welding rod protection layer, metal casting, ceramics, silicone rubber, paint and other chemical industries. 

2) Electrical grade silicon micropowder, mainly used for insulation pouring of ordinary electric devices, insulation pouring of high voltage electrical appliances, APG process injection materials, epoxy potting materials, high-grade ceramic glazes, etc. 

3)electronic grade silicon powder, mainly used in integrated circuits, electronic components, plastic sealants and packaging materials. 

4).The raw material used for fused quartz powder (WG) is the micro-powder of natural quartz that has been smelted at a high temperature, cooled amorphous SiO2 and processed through multiple processes. The product is of high purity and has excellent properties such as low thermal expansion coefficient, low internal stress, high moisture resistance, low radioactivity, and the like. Mainly used in large-scale and large-scale integrated circuit plastic molding materials, epoxy casting materials, potting materials, and other chemical fields. 

5)ultra-fine quartz powder, mainly used in coatings, paints, engineering plastics, adhesives, rubber, precision casting advanced ceramics.

6) nano-SiOx, as an important member of nano-materials, mainly used in electronic packaging materials, polymer composites, plastics, coatings, rubber, paints, ceramics, adhesives, glass steel, drug carriers, cosmetics and antibacterial materials and other fields, It has become a new material for upgrading traditional products. The micro-silica fume is mainly used in several aspects: 

A. Used in mortars and concretes: high-rise buildings, harbor docks, reservoir dams, water conservancy sluice gates, railway highway bridges, subways, tunnels, airport runways, rammed roads and coal roadways Anchor spray reinforcement. 

B. In the material industry: high-grade, high-performance, low-cement refractory castables and prefabricated parts, whose service life is three times that of ordinary castables, and the refractoriness is improved by about 100°C. The high-temperature strength and thermal shock resistance are significantly improved. They are used in: coke ovens. , iron making, steel making, steel rolling, non-ferrous metals, glass, ceramics and power generation industries; large iron ditch and steel materials, breathable bricks, smear repair materials, etc.; self-flowing refractory casting materials and dry and wet spray construction applications; oxides Combining silicon carbide products (ceramic kiln furniture, muffle panels, etc.); high-temperature calcium silicate lightweight heat insulation materials; electric porcelain kiln with corundum mullite push plates; high temperature wear resistant materials and products; corundum and ceramic products; Long-bonded products; In addition to the current widespread use in cast refractories, fused and sintered refractories are also gaining numerous applications. 

C.new wall materials, decorative materials: wall insulation with polymer mortar, insulation mortar, interface agent.

D. cement polymer waterproof material. 

E.lightweight aggregate insulation energy-saving products and products. 

F.the interior and exterior wall construction putty powder processing. 

G.other uses: 

silicate brick raw materials. 

production of water glass. 

used as a reinforcing material for organic compounds. 

Because its composition is similar to that produced by the gas phase method, it can be used as a reinforcing material in rubbers, resins, coatings, paints, unsaturated polyesters and other polymer materials.

 Used as an anti-caking agent in the fertilizer industry. 

5.the difference between the silicon micro-silicon and micro-silica powder indicators From the indicators, the two also have many differences. Specifically, the chemical composition of silicon powder and micro-silicon powder is basically the same, the main components are all silicon dioxide, and the impurities contain sodium oxide, calcium oxide, magnesium oxide, iron oxide, aluminum oxide and the like. However, the silicon content of silicon powders is relatively high, which is basically above 99%; 

while the silicon content of microsilica powders is generally 80-92%, and 94% or more are very uncommon. 

From the aspect of particle size, silicon micro-powder is processed from natural quartz and has a relatively large particle size, with 200 mesh, 300 mesh, 400 mesh, 500 mesh, 600 mesh, 800 mesh, 1000 mesh, 1250 mesh, 3000 mesh, 5000 mesh, etc. , is a powder state. Microsilica fines less than 1μm accounted for more than 80%, the average particle size of 0.1-0.3μm, is a gray state. In actual trade, the price of silicon micropowder is related to the number of meshes. 

The higher the number of meshes is, the higher the price is. The current market price of silicon micropowder is 200 mesh 500 yuan/ton, 325 mesh 600 yuan/ton, 400 mesh 750 yuan/ton. , 500 heads 950 yuan / ton, 600 heads 1,200 yuan / ton, 800 heads to 1,500 yuan / ton, 1000 heads to 2,200 yuan / ton, 1,250 heads to 2,600 yuan / ton, 3000 heads to 6,200 yuan / ton, 4000 heads to 8,400 yuan / ton; The price of micro-silica fume is related to silicon content and moisture, and the degree of burning. In general, the micro-silica fume containing 85% of silicon has a factory price of 1,700 yuan/ton. 

From the market perspective, the potential market for micro-silica fume is larger than that for silicon micro-powder, and there is still much room for development in the domestic micro-silica fume market. Above we can see that there is an essential difference between microsilica and microsilica. Different nature determines the difference in the use of the two. In the future commercial trade, it is necessary to distinguish the concepts and differences between the two to increase the success rate of trade.

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