Also called micro silica or silica fume cohesion, also called silica fume. Is iron alloy in smelting ferrosilicon and industrial silicon, silicon metal, mineral hot furnace produce large amounts of volatile SiO2 and Si gas, gas emissions and air rapid oxidation condensation precipitation. In the 1980s, China's most ferroalloy production enterprises environmental protection facilities is not perfect, silica fume is discharged into the nature, serious pollution of the environment, in the 1990s, with the countries of the importance of protecting the environment, many domestic ferrosilicon and industrial silicon production enterprises are installed flue gas dust removal facilities, silica fume for recovery and utilization. And continuous introduction of the world's advanced technology, the transformation of equipment, improve the production of silica fume, quality.
It is understood, micro silica is very difficult in the recovery process. Because of the micro silicon powder particle size is too small, mechanical dust collector, including dust dust, inertial dust collection and rotation of the settlement, simply capture set to it. It is also very difficult to catch the water film dust catcher. And micro silica fume than resistance is particularly high, up to 1013 Omega - cm, if the constant current electric dust removing device, will produce anti corona phenomenon, is difficult to capture it. If the use of the international advanced electric dust removal device - pulse electric dust collector, from its performance, can capture high specific resistance dust, but its equipment investment is very expensive, about 10 times the conventional electric precipitator. So the current domestic and foreign capture device of micro silica fume set most of the big bag dust collector, the reason why it is in the cloth bag dust remover ahead of the crown in "big" word is due to the characteristics of the dust. If the bag dust collector for collecting dust in general experience is directly used to capture micro silica, may not reach the expected effect. At present America, the former Soviet Union, Norway and other countries are also adopting large bag trapping micro silicon powder. Many enterprises in our country have adopted this method, however, there are some problems in this method:
First, in industrial silicon and ferrosilicon in the smelting process, the exhaust gas temperature is high, up to 500 to 600 DEG C, and very unstable, which is totally due to production status, so in front of the bag dust removing device must be set cooling device, it also increased the investment of dust removal equipment, otherwise will burn the bag.
Second, dust removal equipment failure rate is high. Due to the micro silica fume particles of very fine viscosity is large, it is not easy to rapping cleaning, serious influence on the dust removal effect, at the same time, increasing the resistance of the system, energy consumption increases. And easily lead to broken bags, bags, at this time is bound to stop repair, will affect the normal production, but also increased the maintenance of zero.
Third, high operating costs. The essence of the bag type dust collector is used to donate dust cloth filter gas.
It is very important that how to select a good travel market with the characteristics of high temperature and particle size of the flue gas. Even so, running time is not long, cloth hole will be blocked, regular cleaning, also did not reach the required gas flow, prone to breakage phenomenon of cloth, bag replacement cost is very high. A more serious problem is the cloth resistance increases, the required power is also increased.
Currently on the market with a new micro silica fume collecting device, the device is the technical route of new high-voltage electrostatic collection method and completely different from conventional bag trapping methods. The high voltage electrostatic trapping device is not used in the current domestic and foreign conventional power supply power supply, but the soft characteristic is difficult to be used as power supply. From the body structure, the use of conventional fixed plate line type and the way to sleep and hit the dust, but the use of mobile dust collection pole and the way of cleaning dust. This device has the following outstanding characteristics as compared with the big bag filter.
First, low investment. Full set of equipment investment, a large bag filter 70%;
Second, low operating costs. The power required for each level of the kVA furnace blower is 12KW, which is equivalent to 20% of the bag filter;
Third, low failure rate. In the process of operation, there is no broken bag, the bag of the impact of the production problem, the machine is very low, basically to maintain synchronous operation with the main equipment. Maintenance management is very convenient;
Fourth, operability is good. The equipment and materials used in the whole set of equipment are made in China, and it is a general material.