1. Blast furnace
Blast furnaces are widely used in the rough smelting process of copper, lead, lead-zinc, antimony and other metals. The blast furnace consists of a furnace top, a furnace body, a main bed (also called a throat), a furnace cylinder, and a tuyere device. Smelting furnace charge (concentrate, sintered ore, etc.), coke, flux, counter-material and other solid materials are added from the furnace top. The high-pressure air blown into the tuyere device on the lower side of the furnace body melts, oxidizes, reduces and reacts with the downward materials in the process of moving upward to complete the smelting process. Liquid metal, matte and slag are discharged from the throat or furnace cylinder at the bottom of the furnace, and flue gas, smoke, gaseous metal or metal oxide is discharged from the flue gas outlet on the furnace top. At present, most of them have closed furnace tops, and the furnace body is fully water-jacketed. Refractory materials are only used in the throat and furnace. Because its slag is alkaline slag, the throat part is mainly made of magnesia bricks, magnesia-chrome bricks, and aluminum-chrome bricks; the side walls of the furnace and the upper part of the furnace bottom are made of magnesia bricks, magnesia-chrome bricks, and aluminum-chrome bricks; the furnace bottom is built in an anti-arch shape.
2. Reverberatory furnace
Reverberatory furnaces include smelting reverberatory furnaces and refining reverberatory furnaces. Their structural forms are basically the same, but the refining reverberatory furnace is smaller in size. It is a rectangular furnace body, and the production is continuous. The operating temperature of the reverberatory furnace head is generally 1400-1500℃, and the temperature of the flue gas out of the furnace is generally 1150-1200℃. The furnace bottom is composed of asbestos board, insulation brick layer, clay brick layer, magnesia-aluminum brick or magnesia brick layer from bottom to top. The furnace wall is mostly made of magnesia-aluminum bricks or magnesia bricks. Some important parts are built with magnesia-chrome bricks to extend the service life, and the outer wall is generally made of clay bricks. The furnace top adopts a hanging type furnace top, and the small reverberatory furnace top adopts a brick arch, and the arch material is magnesia-alumina brick.
3. Isa furnace (Ausmelt furnace)
The furnace bottom is generally an anti-arch, which is inclined about 2% toward the discharge port, or it can be a flat bottom, which is also inclined 2% toward the discharge port. The lining is divided into three layers: the upper working layer is made of fused rebonded magnesia-chrome bricks and semi-rebonded magnesia-chrome bricks; the lower part of the working layer is magnesia-chrome ramming material; the bottom is low-porosity clay bricks.
The working conditions of the furnace wall are very harsh, and the lower part (1000~2000mm from the furnace bottom) is eroded and washed by the strongly stirred melt. Therefore, fused rebonded magnesia-chrome bricks or semi-rebonded magnesia-chrome bricks with good high temperature resistance, scouring resistance and corrosion resistance are used.
The upper part is eroded by splashing slag and washed by high-temperature flue gas, and it is also appropriate to use direct-bonded magnesia-chrome bricks with the same material as the lower part of the furnace wall or with weak slag corrosion resistance.
Due to the complex structure of the furnace roof and the harsh working conditions, it is advisable to use magnesia-chrome castables that are easy to construct and resistant to corrosion. In order to increase its anti-stripping performance, some heat-resistant steel fibers can be added to it.
4. Kaldo furnace
The lining of the Kaldo furnace is composed of fused semi-rebonded magnesia-chrome bricks, directly bonded magnesia-chrome bricks, magnesia sand and refractory fiber felt. The fused semi-rebonded magnesia-chrome bricks are directly in contact with the liquid metal, liquid slag and furnace gas in the furnace during the blowing process, and are subjected to strong chemical erosion and mechanical scouring; during the rotation of the furnace body, the lining is constantly subjected to stress changes due to the deadweight of the furnace; the structure of the fused semi-rebonded magnesia-chrome refractory material combines the characteristics of directly bonded magnesia-chrome refractory materials and fused rebonded magnesia-chrome refractory materials. The products have strong slag erosion resistance and good thermal shock stability. It is a suitable lining material for the Kaldo furnace. Directly bonded magnesia-chrome bricks are used as permanent lining refractory materials, which have thermal shock resistance and corrosion resistance and can protect the furnace shell. There is a layer of magnesia sand filler between the bricks to reduce the pressure of the thermal expansion of magnesia-chrome bricks on the furnace shell and facilitate the construction and dismantling of the furnace. There is a refractory fiber felt with a thickness of 10~30mm close to the furnace shell, which plays a role of heat insulation. Practice has proved that laying a filling layer of appropriate thickness between the lining bricks and the furnace shell will not only not reduce the life of the furnace lining, but also reduce the heat loss of the furnace body, save fuel, and improve the operating conditions around the furnace.