How to choose refractory brick used for different parts of blast furnace?
When choosing refractory brick used for different lining parts of blast furnace, we should follow some principles. The refractory lining of every part should fit the parts thermal current intensity, so that the lining can maintain previous vertebral shape and stability under the impact of strong heat flux.
Here are some methods of selecting refractory brick for every part of furnace lining.
(1) Furnace throat. It mainly needs to withstand impact and abrasion of burden, so generally we use steel brick or water cooling steel brick for the furnace throat.
(2) The upper shaft. Plus the burden descent and ascending gas flow of scour and wear. Therefore, we should choose resistance to chemical erosion and abrasion resistance of refractory materials, the most appropriate is high relative density brick, high density, high aluminum brick or phosphoric acid impregnated clay brick.
(3) The middle and lower part of furnace and furnace bosh. The main mechanism of damage is thermal shock, high temperature gas scouring, and impact of alkali metals, zinc and carbon deposition, as well as chemical erosion of the initial slag. For those three parts, we should choose refractory materials with properties of thermal shock resistance, slag erosion resistance and erosion prevention. For blast furnace whose volume is smaller than 1000m3, we can use aluminum carbon brick.
(4) Furnace bosh. Hot gas erosion and iron slag erosion are the main reasons for furnace bosh damage, this part of the heat flux intensity, refractory material life not long (as long as 1 to 2 months, as short as 2 to 3 weeks), generally used in refractory degree is high, load softening temperature is high and the volume density of refractory material, such as the high aluminum brick, alumina carbon brick.
(5) Hearth tuber. This site is only in blast furnace of oxidation reaction area, high temperature from 1900 to 2400 DEG C, lining by damage caused by high temperature thermal stress. Composite brick masonry hearth tuyere zone is adopted by the modern blast furnace, material for high alumina, corundum Mo mullite; corundum and silicon nitride combined silicon carbide, useful also hot pressed carbon block.
(6) The lower part and bottom of hearth. For those two parts, we use hot pressing small carbon brick, micro porous carbon brick, and hot semi graphite carbon brick with high thermal conductivity, good resistance to penetration, good resistance to chemical erosion, low porosity and micro aperture, as well as brown corundum or gray corundum brick used for ceramic cup.