Slag Testing

Slags are an important by-product of iron and steelmaking and are commonly used in a number of secondary products, including aggregates and cement. Corus Research, Development & Technology (RD&T) Group can perform standard quality tests for blast furnace and steelmaking slags, as well as conducting specific research programmes. Corus has extensive experience in the testing and re-use of slag materials

The new European standards EN1097-2:1998 and EN1744-1:1998 contain the industry standard tests for slag used as an aggregate. Corus can perform the following EN tests:

• Los Angeles test (resistance to fragmentation)
• Dicalcium silicate disintegration of air-cooled blast furnace slag (UV test)
• Iron disintegration of air-cooled blast furnace slag
• Expansion of steel slag (steam test)

Corresponding British standards will not be withdrawn until 2003. Many of these tests can be also carried out, together with other tests not detailed in the standards, including:

• Free lime in steel slag by ICP
• Free lime in steel slag by acid titration
• Calcium hydroxide and calcium carbonate by thermogravimetric analysis
• Petrographic examination by reflected and transmitted light microscopy, including hot stage microscopy up to 1500°C.
• X-ray diffraction and image analysis

Detailed examination of slag can be undertaken utilising a variety of techniques. Recent work includes identification of slag types, assessing old slag tips for use as construction aggregate, glass content and crystal size in pelletised slag, mineral phases present and degree of assimilation of additives and assessing the effectiveness of various weathering routines for steelmaking slags.

Benefits to be gained by investigation of slag re-use:

• reduction in landfill, both in terms of volume and cost
• provides a source of additional revenue to the business, typically a 3Mt/a steelworks may generate a net gain of around $14M /a for selling rather than landfill (dependent upon landfill costs)
• highly visible contribution to improvements in environmental activities
• recovery of old slag dumps are also potential income generators and may release land infill for other use
• used to ensure the quality of the slag is suitable for resale