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FAQ 1 : Question: What is blast furnace slag?

Answer: ASTM C 989-05 and CSA A3000-03 define slag as a "non-metallic product consisting essentially of silicates and alumino silicates of calcium and other bases, that is developed in a molten condition simultaneously with iron in a blast furnace."

FAQ 2 : Question: How is blast furnace slag made?

Answer: During the production of iron, the blast furnace is charged with iron ore, flux stone (limestone, dolomite) and coke for fuel. Two products are obtained from the furnace: molten iron and slag.  These materials exit the furnace at approximately 2,700 F, resembling molten lava.  The slag is cooled and solidified by any of four methods: air cooling, granulating, expanding and pelletizing.

FAQ 3 : Question: What is blast furnace slag used for?

Answer: Processed blast furnace slag can be used in a variety of applications. Most common examples include granulated / pelletized slag as a raw material for grinding into slag cement, air cooled slag as engineered road base and pelletized / expanded slag for the production of lightweight concrete for blocks.

FAQ 4 : Question: How much blast furnace slag does Lafarge process?

Answer: Annually, Lafarge Slag processes approximately 1 million tonnes.

FAQ 5 : Question: Are there different types or grades of blast furnace slag?

Answer: Slags differ in chemical composition based on the raw material fed into the blast furnace and the operating practices, but are generally similar.  ASTM C 989-05 classifies slag cement, produced by grinding granulated / pelletized slag, into three grades - Grade 80, Grade 100, Grade 120 - based on their physical properties.

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