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Stabilization of Reactive Aluminum-Water Sludges

IP.com Disclosure Number: IPCOM000047727D
Original Publication Date: 1983-Dec-01
Included in the Prior Art Database: 2005-Feb-08
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Brown, CA: AUTHOR

Abstract

Current industrial processes for diamond turning of aluminum (Al) disk substrates produce 3% fine Al particles. These fines have been collected dry in the past, but fire codes and other considerations, including Al industry practice, have indicated a change to a collection system using water. While this eliminates the dust explosion hazard of dry collection, it presents a reactive hazard. Water and aluminum react to liberate explosive hydrogen gas. Damp Al fines are extremely flammable, and sludges of Al dust and water have been observed to heat and pressurize their containers, apparently spontaneously. These problems currently mandate an expensive process which involves draining sludge from the collection system, mixing with a large quantity of sand, and packing the mixture into steel drums for shipping.

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Stabilization of Reactive Aluminum-Water Sludges

Current industrial processes for diamond turning of aluminum (Al) disk substrates produce 3% fine Al particles. These fines have been collected dry in the past, but fire codes and other considerations, including Al industry practice, have indicated a change to a collection system using water. While this eliminates the dust explosion hazard of dry collection, it presents a reactive hazard. Water and aluminum react to liberate explosive hydrogen gas. Damp Al fines are extremely flammable, and sludges of Al dust and water have been observed to heat and pressurize their containers, apparently spontaneously. These problems currently mandate an expensive process which involves draining sludge from the collection system, mixing with a large quantity of sand, and packing the mixture into steel drums for shipping. It has been found that the sludge samples can be stabilized by the addition of 1-5% of sodium bicarbonate, which appears to suppress hydrogen evolution and the "souffle" effect, i.e., formation of a thick, spongy mass of Al dust, water, and hydrogen from sludges upon standing. Sodium bicarbonate is a harmless, non-toxic, non-corrosive agent, compatible with steel tanks as well as other construction materials. It represents no environmental hazard. The mode of action of this stabilizer is not certain, but may involve control of pH at a level where the oxide coating (normally present) on Al particles is stable and r...