Description
In the production of iron, iron ore, iron scrap, and
fluxes (limestone and/or dolomite) are charged into a blast furnace
along with coke for fuel. The coke is combusted to produce carbon
monoxide, which reduces the iron ore to a molten iron product. This
molten iron product can be cast into iron products, but is most
often used as a feedstock for steel
production.
Blast furnace slag is a nonmetallic coproduct
produced in the process. It consists primarily of silicates,
aluminosilicates, and calcium-alumina-silicates. The molten slag,
which absorbs much of the sulfur from the charge, comprises about
*0 percent by mass of iron production. Figure **1 presents a
general schematic, which depicts the blast furnace feedstocks and
the production of blast furnace coproducts (iron and
slag).
Granulated Blast Furnace
Slag
If the molten slag is cooled and solidified by rapid
water quenching to a glassy state, little or no crystallization
occurs. This process results in the formation of sand size (or
frit-like) fragments, usually with some friable clinkerlike
material. The physical structure and gradation of granulated slag
depend on the chemical composition of the slag, its temperature at
the time of water quenching, and the method of production. When
crushed or milled to very fine cement-sized particles, ground
granulated blast furnace slag (GGBFS) has cementitious properties,
which make a suitable partial replacement for or additive to
Portland cement.
Granulated Blast Furnace Slag has a glassy
structure and can be used as a fine aggregate or binder. GBFS
is commonly used in the manufacture of blended cements where it is
inter-ground or blended separately with cement usually at a *0% -
*0% proportion. Unblended GBFS is can be used in road
pavements and building products.
