Simple Solutions That Work! Issue 9

Contact: ROD NARO [email protected] immediately reduced furnace capacity and contributed to increased power consumption. After 48 hours of operation, three inches of buildup occurred along the entire sidewall. (see Figure 4) Foundry G initially incorporated 2 pounds of Redux EF40L flux per ton of charge, added to each back-charge to determine its effect on buildup. EF40L was added to the furnace before back charging on top of existing molten metal to ensure excellent mixing, (a minimum 50% molten metal bath). Immediate improvements were observed and buildup along the sidewalls was essentially eliminated. Since the optimum refractory thickness is maintained, it is estimated that the power utilization increased by 25% compared to pre-buildup days. Energy savings have been estimated to approach $14.4K a month or $174K per year based on electrical usage of 550 kW/ ton and an electrical rate of $0.069 per kilowatt resulting from the percentage of rated power reduced by 25% (125% with buildup compared to 100% with no buildup). Foundry G observed the following benefits by using Redux on a continuous basis: • Using Redux EF40 has reduced charging hang up issues due to cleaner refractory walls • Reduced power consumption during each melt • Hourly maintenance from scraping was greatly reduced • Consistent furnace capacities: Furnace capacity was reduced by 0.95 tons (28.7%) when slag built up to 3 inches thick • Improved “electrical coupling” was observed with improved temperature control • No adverse effects on the dry vibratable silica refractory linings • Estimated electrical savings of $174,000 annually. In summary, insoluble buildup and slag related problems have become serious issues for today’s foundry operations. These problems will likely only increase as the quality of scrap continues to deteriorate. However, using fluxes properly can help alleviate these challenges while increasing melting efficiency and saving foundries time, electricity, and most importantly, improve profitability. References: 1. Saving Electrical Energy in Coreless Induction Furnaces, R. Naro, Wm Duca, Wm Williams, Foundry M&T, 2009 2. "Efficient melting in coreless induction furnaces" GOOD PRACTICE GUIDE No. 50, ETSU, Harwell, Didcot, Oxfordshire, 2000 3. Mike Nutt, Inductotherm private correspondence, Coil Efficiency versus Lining Thickness Graph. Percentage of rated power approximated by authors based on review of the technical literature and discussions with coreless induction experts. 4. Private Communication, Pete Satre, Allied Mineral Products, Dimensions of the Refractory Installation for a 3 Ton Coreless Induction furnace. Co-written by: D. C. Williams ASI International, Ltd., Columbus, Ohio Pete Satre Allied Mineral Products, Inc., Columbus, Ohio BACK-2-BASICS 55