Current developments in the manufacturing
and utilization of granulated blast furnace slag

1 Worldwide production of cement, crude steel, hot metal and GBFS

2 Changes in the crude steel production rate in the months January–
August 2009 in comparison to 2008

3 Monthly production rates of crude steel, hot metal and cement inland shipping quantities in Germany 2008/2009

4 Draining off the blast furnace slag

5 Transformation of a melt into glass [27]

6 Formation of top crust in the slag ladle of a central granulating plant (Bochumer Verein, 1939)

7 Modern granulating plant [28]

8 Effect of granulation water temperature on the particle morphology

9 Effect of granulation water temperature on the GBFS reactivity

10 “Freezing” of a state of higher disorder due to rapid cooling [27]

$11 Glass contents in individual GBFS fractions$

11 Glass contents in individual GBFS fractions

12 Granulation in the melt laboratory of the FEhS Institute

13 Dynamic viscosity of blast furnace slag as a function of the chemical composition

14 Effect of viscosity on the granulation properties of blast furnace slag

15 GBFS with low basicity produced in the lab from air-cooled blast furnace slag

16 Strength development of a blast furnace cement containing GBFS with low basicity produced in the lab from air-cooled blast furnace slag (GBFS/clinker = 75/25)

17 Superficially “bonded” GBFS particles after open-air storage for a period of more than 30 years

18 Contradiction between Blaine value and “real” particle size distribution at high loss on ignition of the GBFS

19 “Flow tracks” in a ground GBFS particle (1830 cm²/g)

20 “Flow tracks” in a ground GBFS particle (1940 cm²/g)

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Summary: Due to the necessity to reduce CO₂ emissions in cement making the partial substitution of cement clinker by granulated blast furnace slag (GBFS) has become established. This article deals comprehensively with the granulation process of GBFS as well as with the effects of the granulating process on the properties of GBFS. However, the properties of GBFS may further be optimized in the cement plant, mainly during the grinding process. In the future also artificial slags or slags from other technical processes with suitable properties could perhaps be used as clinker substitutes.

1 Introduction

Because of its latent-hydraulic properties, granulated blast furnace slag (GBFS) has been employed as a cement component and as a concrete additive for more than 100 years. Formed from liquid blast furnace slag, it is a by-product of hot metal production in blast furnaces and thus of the steel manufacturing process. 65 % of all the steel manufactured worldwide comes from the blast furnace/LD converter while only 35 % is produced by the electric furnace process. GBFS is created by the dispersion and extremely rapid cooling of liquid blast furnace slag by means of water or air...

ZKG 03/2010

ZKG 03/2010

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