Simple Solutions That Work! Issue 9

The following example illustrates how flux additions can improve melting efficiency. Foundry G is a medium sized foundry that manufactures gray iron castings. The foundry has historically experienced extensive slag buildup on the upper sidewalls of its four 3-ton medium frequency coreless induction furnaces in a semi-batch melting operation. With a newly installed lining, melting capacity is 1,525 tons per month with 2 furnaces running 5 days a week, 21 days per month. Foundry G’s charge consisted of 100% metallic fines and machining chips. Each coreless furnace is lined with a silica based dry vibratable refractory. During melting, slag generation and accompanying buildup Improper use of fluxes can rapidly erode refractory furnace linings, especially if potent fluorspar-based fluxes are used. However, if a flux is carefully engineered for specific applications and used properly, refractory life may actually increase. Some foundries using specialty fluxes have reported increased refractory life. One large foundry significantly increased lining life from 11 months to 26 months solely by incorporating Redux EF40 in their operation. Refractory life can also be extended by reduced damage due to mechanical chipping required to remove tenacious slag deposits. Elimination of buildup optimizes power utilization, thereby reducing energy consumption. 54 Figure 2. Effect of Lining Thickness on Coil Efficiency and Percentage of Power Requirements for a 3 ton coreless induction furnace. Figure 3. Typical Slag Build Up in a Coreless Induction Furnace. Figure 4. Insoluble buildup removed from Foundry G's coreless induction furnace after 48 hours of operation.