As a Refractory Material Supplier, share it with you.
Silica Brick for Hot Blast Stove is used to build siliceous refractory products with tridymite as the main crystal phase in the high temperature part of the blast furnace hot blast stove. The hot air temperature of the blast furnace increased from 500-650°C in the 1940s to 1000°C in the 1970s, and the hot air temperature of the large blast furnaces in the 1980s has increased to 1350°C. Due to the increase in air temperature, the clay bricks or high alumina bricks used in the high temperature parts of the previous hot blast stoves are gradually replaced by silica bricks and low creep high alumina bricks.
Silica Bricks
Hot blast stove silica brick has the following characteristics:
(1) Under long-term high temperature and load conditions, the volume is stable and the high temperature creep rate is low, and one or even two blast furnace campaigns can be used continuously.
(2) Good thermal shock resistance above 600℃. Adapt to the variability of the temperature of the hot blast stove to keep the bricks and masonry intact.
(3) The chemical resistance is better than clay bricks and general high alumina bricks. The corrosion of the alkaline substances in the gas and smoke on the silica brick is limited to the formation of a layer of glass on the surface, and no peeling occurs.
(4) The thermal conductivity of silica bricks is larger than that of clay bricks and high alumina bricks, which is conducive to storing and releasing heat in a shorter time.
The shape of the product should be regular and the size deviation should be small. The hole diameter of the checker bricks should be ±1mm. The bricks used in other parts should not exceed ±1%. If the joints of the upper pipe of the external combustion hot blast stove are made of combined bricks, they must be cut before masonry. Grind and pre-assemble. The width of the surface crack is not more than 0.5mm, and there should be a length limit side. Cracks with a width of less than 0.1mm will not affect the use, and there should be no cracks caused by improper cooling.
Use quartzite containing 98% SiO2 to crush into particles and fine powder less than 2.5mm. Stored separately according to particle size, using appropriate gradation. Add mineralizers and binders, knead in a wet mill, and then shape them on a brick press. After the bricks are dried, they are fired at a temperature of 1308-1450°C. Products after cooling should be selected one by one.
It should be stored in a waterproof warehouse, and it can still be used after being dried slowly at a temperature below 100°C after being wet. After freezing, the strength of hydrated silica bricks will be affected, and they need to be inspected again. Furnace construction should leave expansion joints according to the thermal expansion rate provided by the manufacturer. The temperature-time heating curve of the oven should be formulated reasonably, especially in the stage of intense expansion before 600℃, which should be strictly controlled.
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