How silica fume use for refractory?

- Jul 25, 2017 -

How silica fume use for refractory?

Micro-silica fume used to improve the refractory has more than 40 years of history, micro-silica fume for refractory materials will have the following characteristics:

1. To improve the flow of refractory refractory materials, reduce water consumption, making it easy to shape, greatly improve the production efficiency;

2. Due to the interstitial action of its ultrastructure, the compactness and strength of refractory materials have been greatly improved.

3. Micro-silica fume with high activity, in the presence of Al2O3 components under the premise of more easily generated mullite phase, so that refractory high temperature strength, thermal shock significantly improved.

According to the different performance of refractory materials, orthogonal design, through the comparative test, select the best formula, the company's technical experts can help the refractory plant to work. Refractory materials usually use non-encrypted micro-silica fume. In addition to casting refractories in the general use, in the fused and sintered refractories are also a lot of applications. Such as the use of low-cement castables, low-cement castables developed in the 1970s a new type of high-performance refractory castables, first developed by the French success. It is widely used in a variety of industrial high temperature furnace, a very good technical and economic results. In 1983 the United States Pittsburgh City General refractory company will be low cement castable for dry blast furnace main trench ditch cover lining, the service life is three times the original castable, from 75-100 furnace to 300-400 furnace. Metallurgical Department of Building Research Institute since 1985 for low-cement castables research, in 1988 through the ministerial-level identification. It has been used in Baosteel, Shougang thermal equipment.

Low cement castables and ordinary castables use calcium aluminate cement. , But with the pre-mixed with silicon powder and superplasticizer, the cement dosage of 4-8%, adding only 5-8% of water, compared with the latter 15-20% of cement, water 10-15% Amplitude reduction. Low cement castables not only save 50-70% of expensive aluminate cement, but also improve performance. Metallurgical Department of Building Research Institute of low cement castables test results are as follows:

Porosity and pore structure to reduce the cement castable and ordinary castable at 1400 ℃ after heating the apparent porosity comparison, the former was 20.4%, while the latter was 26.4%, an increase of nearly 30%. The total pore size of the low cement castable is lower than that of the ordinary castable by the pressure pump method. The general castable after heating at 800 ° C increased by nearly 40% when dried at 110 ° C. From the pore size distribution, the pore size of more than 100A in the common castable is 2-3 times of that of the low cement castable, and the pore size of less than 1000A is only 30-50% of the low cement castable. Strength characteristics of low cement castable strength, whether low temperature, medium temperature and high temperature stage can continue to grow, while the general castable medium temperature strength decreased significantly. The hot compressibility of the two castables is as follows: 1100 ° C * 1h 1400 ° C * 1h

Low cement castable 9.4Mpa 2.0Mpa

Ordinary castable 4.8Mpa 0,7Mpa line changes in the heating, the low cement castable shrinkage value is lower than the ordinary castable, to 1500 ℃, low cement castables appeared 0.1-0.8% micro-expansion, so the material will not There is a crack. The refractoriness is measured and the refractoriness of the low cement castable is 1790-1830 ° C, higher than the ordinary castable (1690-1710 ° C). Load softening point test results are as follows: ordinary castable low cement castable

Load softening point KD 4% KD 4% Temperature, ° C 1170 1325 1240 1395 Thermal expansion at 1400 ° C The two castables are substantially identical. After 1400 ℃, the low cement castable began to expand after shrinkage, and the expansion rate was 1.5% at 1500 ℃, while the castable was drastically shrink at 1400 ℃. The expansion rate at 1500 ℃ was negative (-1.8%). Resistance to corrosion test with converter slag heated to 1450 ℃, constant temperature 3 hours, low cement castable erosion rate of about 4CM2, better than ordinary castables 7CM2. So far, the rule of the General Hospital has successfully developed a variety of grades of DJ cement castables and used for many projects. DJ-C165Z, DJ-C17Z two low-cement castables are in Baosteel blast furnace trench cover. The original Japanese imports of castables usually life of 20 days, now all the domestic low-cement castables instead, the average life expectancy is about 20 days. Up to 26 days, save a lot of foreign exchange. DJ-C70, DJ-60 low cement castable for Shougang 250 step heating furnace and 430 heating furnace burner brick. 250 without into the furnace life of 9 months (the original use of only half a month), increased nearly 20 times. DJ-C60 low cement castable for Shougang 500 open billet furnace by high temperature steam erosion erosion serious depressing parts, the use of a year is still intact.

According to the available data, low cement castables are widely used in coke oven, sintering, ironmaking, steelmaking, rolling, nonferrous metallurgy, petroleum and chemical, cement, glass ceramics and power generation industries.

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