Reducing Airborne Silica During Coreless Furnace Lining Using A Refractory Installation System--Best Available Technology

摘要

Silica refractory with a respirable fraction of quartz at approximately 99 percent has long been the refractory of choice for lining coreless induction furnaces. About 80 percent of foundries use coreless furnaces in the United States to melt ferrous and nonferrous metals. Furnace lining is often overlooked in foundries as a potential source for silica overexposure when high risk activities are listed. It may be because the melting operation is less visible than other production departments and linings typically occur on weekends. A random sampling of 24 U.S. foundries lining furnaces with silica shows that workers are exposed an average 8.6 hours during a furnace rebuild and 54.3 times annually, far more frequently than many believe. The annual average exposure rate for this group based on a work year of 1950 hours is 467 hours or 24 percent of time spent working in very hazardous conditions. A refractory installation system was introduced to the market specifically to redress the hazardous health and safety concerns associated with lining a furnace manually. Its effectiveness in reducing silica overexposure is shown by repeated air samples as low as 5 to 10 times below OSHA's permissible exposure level for respirable silica. In addition, the advanced technology has permanently eliminated the laborious tasks associated with lining a furnace that typically can lead to compensable injury. Significant and sustained production improvements have been shown at all foundries using the system. Lining life improvements are reported between 50 and 75 percent and higher tonnage through put per campaign has resulted from the extended refractory life. Dramatic labor savings are realized because only two workers operate the machinery despite the size of the furnace. The refractory installation and vibration system has provided a permanent solution to significantly reducing airborne silica and resolving other safety and health hazards when lining a coreless furnace.