A planned modification to a cement kiln at the Holnam Portland Cement Plant near Florence, Colorado required the removal of a ring of cast-in-place (CIP) refractory lining. The CIP lining was approximately 14 inches wide, 12 inches thick and 38 feet in circumference.In the original plan, the liner was to be removed with 60 pound paving breakers. It was believed that the removal could be accomplished in one day. However, due to the hardness of the liner, at the end of one day only eight feet of the 38 foot circumference was mechanically removed by two men using the pavement breakers. At this rate, it was apparent that mechanical removal would require at least 4 more days, which would delay the kiln start up at great expense to the company.In hope of getting the project back on schedule, the Quarry Supervisor was consulted to evaluate whether controlled blasting techniques might be used to quickly remove the liner. A small test shot was designed and fired with good results. Twenty-seven small diameter holes were drilled during the night. The holes were loaded with small charges early the next morning. The blast successfully removed the remaining liner without damaging the kiln. Over four days of down time were prevented by this successful blasting technique.This paper explains the process that was used to prepare the initial test and full scale blasts. Details of the drilling, explosive charges, initiation system and other practical elements of the blasting are also included.
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