Ovako's steel production generates residual products such as slag, mill scale, refractories and iron sulphate. Thanks to good planning and business thinking, much of this can toady be sold at a profit. Annual production of 450,000 tonnes of steel at Ovako in Hofors alone provides 90,000 tonnes of residual products, not including scrap.
"Residual products are resources we must utilise, not least for the environment," says Kjell Pålsson, residual product manager at Ovako in Hofors.
Ovako began targeted efforts in 2000 to reduce the amount of material taken to landfill. By late 2008, most of the residual products had found their use.
Mill scale instead of iron ore
Ovako currently produces a number of products in addition to steel:
• Mill scale from rolling mills/tube mills/ring mills consists of iron oxide. This product can replace iron ore as a raw material in, for example, the production of crude iron, ferrosilicon, ferrochromium or cement. There is currently great demand from customers producing ferrosilicon, and from manufacturers of heavy concrete. This latter is used, for example, in counterweights for cranes and hoists.
• External companies extract zinc from the filter dust from the Electric Arc Furnace in the steel mill.
• There are also refractories from the steel mill's casting system and from the linings of furnaces. These are recycled and used in the manufacture of new bricks or refractory masses.
• Another residual product, iron sulphate, can be used in cement production and in water purification.
The majority of residues consists of slag.
"By changing the slag forming recipe or adjusting the way the steel mill is run, we can control the slag mineral composition so that it becomes a construction material with excellent properties", says Kjell Pålsson.
"Some slag goes to asphalt production, but we are constantly working on developing new applications. It feels good to do something positive for the environment. We only have one earth, and we need to be careful with the available resources," says Kjell Pålsson.