Aluminum smelting is a very large global industry. There are many different options for smelting facilities and systems, but a blast furnace is a common option and one that offers a long-life cycle and a cost-effective process.
Within the blast furnace systems, carbon blocks and used in several areas. There are carbon cathode blocks in use, but there are also carbon blocks that are used in the lining of the furnace hearths. It is in this latter type of application that carbon provides a top material with different options to consider to stand up the demanding environment and high temperatures required for the process.
The Basics
The basic type of carbon blocks that are used for this purpose are known as carbon refractories. These are not pure carbon but rather a mixture of carbon filler materials with coal tar or petroleum pitch which becomes the binder.
Depending on the manufacturer, these blocks can be extruded or molded to create the specific size and shape of blocks for different applications. These blocks are then baked in an oven at up to 1400 degrees Celsius to completely fuse the filler and binder.
The resulting blocks can be porous. This results from the evaporation of liquids during the baking process. Additional binders can be used to create specific densities in the carbon blocks and reduce the amount of porosity. There is also material that can be impregnated into the baked blocks. This can be repeated as necessary to develop the required density.
The additional processes after the initial development of the blocks and the baking will add to the overall cost of the particular type of block. However, with increased density and decreased porosity comes a longer life cycle, something that may well be worth considering for small or large aluminum smelting facilities.
