The Use of Steelmaking
Slag in Cement manufacturing
“An Environmental Solution with Commercial Value”
Presentation Objectives:
• Review of Portland Cement Industry Challenges– Short-Term Excess Capacity Issues– Increasing Environmental Regulations
• Chemical Requirements for Clinker Production– Traditional raw material selection
Presentation Objectives:• Review of Iron & Steel Making Process• Converting Slag to Cement Clinker• Commercial Evaluation of Slag as Kiln Feed
– Cost effective solution for improved productivity
– Documented Improvement in reducing CO2& NOx emissions
– Point of introduction evaluation• Slag to Clinker Summary
Chemical Oxide ComparisonRaw Mix for Clinker
(Ignited Basis) Blast Furnace Slag Steel Furnace Slag
% % %
CaO 65-68 42 32-45
SiO2 20-23 15 32-42
Al2O3 4-6 5 7-16
Fe2O3 2-4 24 1-1.5
MgO 1-5 8 5-15
Mn2O3 0.1-3 5 .2-1.0
TiO2 0.1-1 N/A .2-2.0
SO3 0.1-2 .08 1-2
K2O 0.1-1 N/A N/A
Na2O 0.1-0.5 N/A N/A
Cement IndustryGreenhouse Gas Emissions
CO2 Equivalents
Source: US Environmental Protection Agency, The US Inventory of Greenhouse Gas Emissions and Sinks (2005), April 2007
Prepared by the Committee on Energy and Commerce staff – October 2007
1 Ton of Clinker Production ≈ 1 ton of CO2 Emissions
“As slags have already been calcined calcined and contain trace
components that act as mineralizers, they can be converted into the clinker
clinker minerals with little or no further energy input into the cement
kiln.”
Dr. Michael Clark – Technical ConsultantInternational Cement Review – Feb. 2003
Steel-Making Process
• Blast Furnace (BF) Slag
• Basic Oxygen Furnace (BOF) SlagIntegrated
• Electric Arc Furnace (EAF) Slag Mini Mills
Lime + Iron + 3000Lime + Iron + 3000°°F = Steel SlagF = Steel Slag
Purifying Steel Produces SlagPurifying Steel Produces Slag
Steel FurnaceSteel Furnace
Calcium OxideCalcium Oxideis added to theis added to themolten Steelmolten Steel
Slag floats Slag floats to the Topto the Top
Portland Cement Compounds
C3S: (Alite) 3 CaO . SiO2 (40-70%)
C2S: (belite) 2 CaO. SiO2 (20-40%)
C3A: 3 CaO. Al2O3 (3-17%)
C4AF: 4 CaO . Al2O3 . Fe2O3 (5-15%)
Converting Slag to ClinkerConverting Slag to Clinker
CC22S to CS to C33S S -- Exothermic ReactionExothermic Reaction
CC33S + Heat S + Heat C2S +C2S + CaO CaO + Heat =+ Heat =
SteelSteel--making making Slag Slag
MinimumMinimumHeatHeatLimeLime Clinker PlusClinker Plus
Heat is ReleasedHeat is Released
Commercial Evaluation of Slag As Kiln Feed
• Incremental Clinker Requirements?- Cost of outside clinker purchases
• Is Facility Permitted to Generate Additional Clinker?• Is Company Motivated to Reduce CO2
and/or NOx emissions?• Does Facility Have Production Bottlenecks?
- Raw Grinding- Feed System- Clinker Cooler- Finish Grinding
Commercial Evaluation of Slag As Kiln Feed (continued)
• Compare Existing Raw Mix With Adjusted Raw Mix Utilizing Slag- Additional Savings Associated
With Purchases, Grinding costs or full requirementof materials
• Prepare Proforma Based Upon Plant Specific Information
• Implement Pilot Test- Utilize established protocol for accurate evaluation
Andover Technology Partners“An Environmental Evaluation of Steelmaking slag
in Cement Manufacturing”
MildothianMildothian, TX , TX -- Long WetLong Wet
OroOro Grande, CA Grande, CA -- Long Long DryDry
Hunter, TX Hunter, TX -- PrecalcinerPrecalciner
TXI Facilities TXI Facilities -- Three Kiln Three Kiln TechnologiesTechnologies
38.4
0.0
38.7
3.6
20
30
40Tons per
Hour Clinker
Pre-Steel Slag Steel Slag
Clinker From Raw Fd Slag TPH
Steel Slag Testing Data : Steel Slag Testing Data : Midlothian Plant ProductionMidlothian Plant Production
10% Increase in Production10% Increase in Production
Raw Materials ImpactRaw Materials Impact--MidlothianMidlothian
Pre-Steel Slag Post Steel Slag
Limestone 89% 93%Shale 4% -Sand 6% 7%Mill Scale 1% -
Hunter Production: Clinker TPH, 1992-1997
90
95
100
105
110
115
1992 1993 1994 1995 1996 1997
TPH Before Steel Slag With Steel Slag
Steel Slag Historical Data : Steel Slag Historical Data : Hunter Plant ProductionHunter Plant Production
1.04
0.97
0.6
0.7
0.8
0.9
1.0
Tons CO2 perton clinker
Pre-Steel Slag Steel Slag
Steel Slag Testing Data: Midlothian Plant CO2 Emissions
~ 7% Reduction in CO~ 7% Reduction in CO22 EmissionsEmissions
843
495
0
200
400
600
800
Lbs NOxper hour
Pre-Steel Slag Steel Slag
Steel Slag Testing Data: Midlothian Plant NOx Emissions
> 40% Reduction in > 40% Reduction in NOx NOx EmissionsEmissions
HunterHunter MidlothianMidlothian
Production Increase Production Increase 10%10% 10%10%
Fuel DecreaseFuel Decrease 2.3% 2.3% 12%12%
COCO22 DecreaseDecrease 7%7% 7%7%
NOxNOx DecreaseDecrease 40%40% 48%48%
Steel SlagTest Summary
Steel Slag as aSteel Slag as a NOxNOx Reduction TechnologyReduction Technology
““Kiln temperatures while operating with the Kiln temperatures while operating with the CemStarCemStar
process are significantly lower than under normal process are significantly lower than under normal
conditions. Testing showed that, on average, kiln conditions. Testing showed that, on average, kiln
temperature with temperature with CemStarCemStar is over 200 F lower at the is over 200 F lower at the
Midlothian plant. The lower kiln temperature with Midlothian plant. The lower kiln temperature with CemStarCemStar
results in lowerresults in lower NOxNOx generation.generation.””
Andover Technology Partners CemStar Report Andover Technology Partners CemStar Report
Awards For Awards For Emissions ReductionsEmissions Reductions
1999 1999 -- U.S. EPAU.S. EPA’’s Climate Protection Awards Climate Protection Award1999 1999 -- U.S. EPAU.S. EPA’’s Climate Wise Awards Climate Wise Award
““TXI has shown exceptional leadership, personal TXI has shown exceptional leadership, personal
dedication and outstanding technical achievements dedication and outstanding technical achievements
in protecting the climate,in protecting the climate,”” said Kathleen Hogan, said Kathleen Hogan,
director of the EPAdirector of the EPA’’s Climate Protection Division. s Climate Protection Division.
““We are pleased to recognize their achievements by We are pleased to recognize their achievements by
bestowing this award.bestowing this award.””
Lower Stack Emissions (Lower Stack Emissions (NOx NOx & CO& CO22))
5 5 -- 20% Increased Clinker 20% Increased Clinker ProductionProduction
Better Fuel Efficiency & Kiln StabilityBetter Fuel Efficiency & Kiln Stability
Raw Materials Use and Product FlexibilityRaw Materials Use and Product Flexibility
Minimum Implementation and CostMinimum Implementation and Cost
Summary of BenefitsSummary of Benefits
Kiln Feed Introduction Methods
• Through Raw Milling System• CemStar Patented Technology
– After Raw Milling System– Directly Fed Into Kiln
WEIGHWEIGHFEEDERFEEDER
Process DiagramProcess Diagram-- PreheaterPreheater PlantPlant““CemStarCemStar TechnologyTechnology””
ROTARY ROTARY KILNKILN
PREHEATER PREHEATER TOWERTOWER