The nature and application of silica fume

Silica fume commonly refers to the soot of furnace flue in industrial silicon and ferrosilicon production. Its particle size is extra fine and the composition is mainly about silicon oxide with small density. But it is larger than resistance with strong bonding and adhesion. It is difficult to settlement. With the increase in industrial silicon and ferrosilicon production, the amount of silicon powder generation is also growing. It is estimated that the potential resources of silica fume are more than 400 000 t per year. But many manufacturers in China have no dust recovery units. A large number of silica fume have no recovery, thus it produces great pollutions for the environment.

Silica fume resources development and utilization of research began in the 1950s, existing engineering applications to the late 1960s, domestic and international long-term research and practice, in turn silica fume used in cement, chemicals, rubber and other fields, to obtain a more good results, and the development of a number of excellent new products.

In the 1970s, the Nordic countries, first examine the application of silica fume in concrete, concrete mixed with silica fume performance improved. After the 1980s, Europe and Japan have been carrying out comprehensive utilization of silica fume, and has made considerable progress. For the application of nickel powder in Canada in 1983, in Spain in 1986, convened two international conferences. , Western Europe and North American countries has been mixed with silica fume concrete used in high-rise buildings, highways, bridges and oil platforms and other projects.

Low cement castable is developed in the 1970s a new type of high temperature refractory injection materials, first developed by the French. Low cement castable blended with silica fume and superplasticizer aluminate cement, it can save 50 to 70 percent. Compared with ordinary castable, low cement castable porosity, strength, refractoriness has also been enhanced.

Several years ago to study the silicon powder in the manufacture of sodium silicate (water glass) to be successful. Mostly quartz sand currently manufacture of sodium silicate and its modulus is not greater than 3.5, the use of silica fume system sodium silicate, both removed from the crushing, grinding quartz sand hazards to workers, but also simplify the process, energy conservation and create a modulus greater than 4, sodium silicate. Silica fume as a system to take rubber, resin, mineral raw materials containing silica fume fillers rubber, the relative elongation, pull tear strength and aging resistance are improved. Silica fume instead of white carbon black for rubber industry is entirely possible.

Silica fume with KOH or K2CO3 hybrid heating can be made into a slow concentrated fertilizer potassium silicate, it is difficult to drain, to promote crop root development, inhibition of pests and diseases for metal powder exporter. Silica fume can also be used as a fertilizer anti-caking agent. In addition, the former Soviet Union also used silica fume silicate brick label up to the M250 to M300, when blended with 7% silica fume.

It has been decades of years for foreign countries study on the application of silica fume. In the last twenty years, there are more and more systematic study works in recycling, product development, use and the mechanism. Many countries have set up research institutions and established production plants. Micro-silica fume has entered into the commercialization stage. Although China started late in applications of silica fume, in recent years it has rapid developing progress. On the basis of good electric furnace dust work, China should concentrate on opening up a new way for silica fume application with small investment, low cost, quick and simple process.

Source:http://www.mhcmp.com