ductile iron slag management in - foundry gatefoundrygate.com/upload/artigos/ductile iron... ·...
TRANSCRIPT
Chris DeRosaMarket Manager Metallurgical Products
Washington Mills Hennepin
Ductile Iron Society Annual Meeting May 11‐13, 2010 Surrey BC
Ductile Iron Slag Management inDuctile Iron Slag Management in Coreless Furnaces
Slag Generation and Handling Optionsg g p
Di i f A l i l T i d R lDiscussion of Analytical Testing and Results
Tips on Minimizing Slag Generation
Ductile Iron Society Annual Meeting May 11‐13, 2010 Surrey BC
Slag GenerationInfluential Factors
Ch t i l•Charge materials
•Alloy addition
•Preheat
•Fines removal
Ductile Iron Society Annual Meeting May 11‐13, 2010 Surrey BC
Charge Materials
Steel / Plate / Shred
•Sizing and flowability
•Surface area to weight gratio
•Coated or galvanized steel
•Be aware of micro icontaminants
Ductile Iron Society Annual Meeting May 11‐13, 2010 Surrey BC
Charge MaterialsRemelt / Shop Scrap
Blasted vs unblasted
FlowabilityFlowability
Filters
Ductile Iron Society Annual Meeting May 11‐13, 2010 Surrey BC
Charge Materials
Pig IronGreat surface area : weightG eat su ace a ea : e g tUse magnetic handling
Alloy AdditionUse high qualitUse high qualityProper sizingEarly but not first
Pre Heat / Fines Ensure fines removalAvoid excessive preheatp
Ductile Iron Society Annual Meeting May 11‐13, 2010 Surrey BC
Slag Removal•Raking
•Twirl•Twirl
•Scoop
•Clam Shell
Ductile Iron Society Annual Meeting May 11‐13, 2010 Surrey BC
Slag Removal•Paddles
•Rakes•Rakes
•Spoons
•Refractory coatings
•Clam shells
•Slag coagulant•Slag coagulant
Ductile Iron Society Annual Meeting May 11‐13, 2010 Surrey BC
Slag Testing and SamplingAnalysis with XRD/XRFSmall Sample Size for AnalysisGathering Sample Critical
Gather 10‐20 lbsC h l h kCrush large chunksPull out contaminantsSubmit 3 5 lbsSubmit 3‐5 lbs
Ductile Iron Society Annual Meeting May 11‐13, 2010 Surrey BC
Slag Testing and SamplingDon’t use slag coagulantUse proper toolsCollect sample at the same time during melt cycleCollect sample at the same temperatures
Establish baselineSample frequency
Ductile Iron Society Annual Meeting May 11‐13, 2010 Surrey BC
Slag Testing and SamplingIdeas to Consider
Establish melt slag baselineTake samples from Take samples from holdersTake samples from ladlesConsider primary vsConsider primary vssecondary slags
Track charge conditionTrack charge changesMonitor alloy changesNote any defect trends
Ductile Iron Society Annual Meeting May 11‐13, 2010 Surrey BC
Slag AnalysisTypical Analysis Tramp Elements
Gray Ductile Gray/Ductile
SiO2 65% 55%
Al2O3 10% 15%
MgO 2% 10%
P2O5 <0.5%
K2O <0.5%
TiO2 <1 0%MgO 2% 10%
CaO 5% 5%
MnO 5% 5%
TiO2 <1.0%
V2O5 <0.2%
Na2O <0.2%
FeO 10% 10% Cr2O3 <0.2%
Ductile Iron Society Annual Meeting May 11‐13, 2010 Surrey BC
Slag AnalysisP2O5 B2O3 SiO2 TiO2 Al2O3 ZrO2 FeO PbO CuO Na2O MgO MnO CaO
ACIDIC BASIC
V R i i V Ratio is Sum of Basic Components
Sum of Acid & Neutral Components
V Ratio > 1, Slag is BasicV Ratio = 1, Slag is NeutralV Ratio < 1, Slag is Acidic
Ductile Iron Society Annual Meeting May 11‐13, 2010 Surrey BC
g
Monitoring Slag ChemistrySlag Chemistry Control
Most coreless operations have SiO2 refractory systemsSiO2 refractories require acidic slagImportance of SiO2 in charge
Sources of SiO2Sand on remeltSiC additionDirtAlloy lossyRefractory wear
Ductile Iron Society Annual Meeting May 11‐13, 2010 Surrey BC
Monitoring Slag ChemistrySources of SiO2
Example Foundry “A”Weigh remelt 292.96 lbsBlast remeltRe weigh remelt 291.92g 9 9Weight of sand on remelt 1.04lbs% of sand on remelt 0.355%
They found that there will be 7.1lbs of SiO2 per ton of remelt
Ductile Iron Society Annual Meeting May 11‐13, 2010 Surrey BC
Monitoring Slag ChemistrySources of SiO2
Example Foundry “A”Adds 6000lbs remelt in a 12000lb charge6000lbs x 0.355%=21 lbs sand/chargeSlag weight is 79.74 lbs/12000lb chargeg g 79 74 gSiO2 addition from remelt will be 26.7% of slag weight
Ductile Iron Society Annual Meeting May 11‐13, 2010 Surrey BC
Monitoring Slag ChemistrySources of SiO2
SiO2 from SiC50 lbs SiC addition7% SiO2 in SiC3.5 lbs SiO2 from SiC3 5SiO2 addition from SiC will be 4.4% of slag weight
SiO2 from Remelt (21 lbs) 26 7%SiO2 from Remelt (21 lbs) 26.7%SiO2 from SiC (3.5 lbs) 4.4%Total SiO2 intentionally added (24.5 lbs) 31.1%y
Ductile Iron Society Annual Meeting May 11‐13, 2010 Surrey BC
Monitoring Slag ChemistryAnalyzed SiO2 53.8%Added SiO2 31.1%Diff %
Slag AnalysisMgO 9.81
Al2O3 20.29Difference 22.7%
Slag weight 79 74 lbs
3 9
SiO2 53.8
S 0.05
K2O 0 24Slag weight 79.74 lbsMissing 18 lbs of SiO2
K2O 0.24
CaO 3.58
TiO2 0.34
Alloy LossRefractory
V2O5 0.06
Cr2O3 0.22
MnO 5.57
Dirt FeO 5.05
Ductile Iron Society Annual Meeting May 11‐13, 2010 Surrey BC
Minimizing Slag GenerationEvaluate charge materials thoroughlyP l i &
Fines removal systemIron level in the furnace
Proper selection & addition of alloysUse of SiC
Lid use & conditionSlag coagulant
Use of SiCAvoid excessive preheat
Right tools for the job
Ductile Iron Society Annual Meeting May 11‐13, 2010 Surrey BC