What Happens in
the Melt Shop?

There are a number of different slags
  • Steel Slag
  • Ladle Slag
  • Raked Slag
  • Clean up Slag from furnace pits.

There are different sources - BOF vs EAF

Steelmaker does affect slag quality

Why is the CSA Interested in OPSS?
Ontario produces ~80% of Canada's 16 M tonnes of steel

Cannot make steel without making slag
  • ~1.5 M tonnes BF slag
  • ~1.2 M tonnes "Steel Slag"
Appropriate specifications for the appropriate use of slag aggregates

Technical Reports for OPS Aggregate Standards Sub-Committee

Four Technical Papers:
  • BF slag in HMA
  • Steel slag in HMA
  • Slag for surface treatment
  • Slag aggregate in granular applications

Index of Terms
  • BF - Blast Furnace
  • BOF - Basic Oxygen Furnace
  • EAF- Electric Arc Furnace
  • HMA - Hot Mix Asphalt
  • OPSS - Ontario Provincial Standards Specifications
  • GGBS - Ground Granulated Blast Furnace Slag
  • CSA - Canadian Standards Association
  • MTO - Ministry of Transportation of Ontario

What is Slag?

Slag is a co-product of the manufacture of iron and steel. Essentially it is a mixture of oxides, silicates and aluminates.

History of Slag Usage

Blast Furnace Slag has been used in Canada as a road and plant base material since the early 1900's. Steel Slag was originally used in the 1970's and and consisted of premium surface course HMA. There was extensive use in 1980's and by the 1990's there was in excess of 488,000 tonnes consumed in a variety of applications. Performance problems surfaced however in 1991 (MTO moratorium). Additional technical work and development was conducted on behalf of the industry which lead to process changes, test strips (1992~96), with full commercial use by 1997.

The advances made in HMA has lead to:
  • Better understanding of the customer and their requirements.
  • Segrategate slags
  • Measure the product
  • Mix design
    • avoid 100% steel slag mixes
    • more problems with SSA fines
    • natural sand for better compaction
  • Better supervision of HM plant and contractor.

Good Hot-Mix Requires All!

  Steelmaker only controls aggregate.

Influence includes:
  • quality
  • stockpiles
  • aging
  • loading

There is a Slag Value Chain

Pre 1991 steelmakers barely looked beyond the slag processor. Some customers stopped using SSA because of price, not quality. More people than just the slag producer affects final product.