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Passivation of Aluminum Fines

IP.com Disclosure Number: IPCOM000047437D
Original Publication Date: 1983-Nov-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Brown, CA: AUTHOR [+2]

Abstract

Aluminum fines resulting from turning operations of aluminum (Al) disks are explosion-prone. In the presence or absence of kerosene, the fines can be ignited by welding sparks or other sources of high temperature and subsequent efforts to extinguish the fine with water naturally have to fail due to the generation of H2 gas on contact. Various suggestions aimed at rendering the fines inactive have been proposed; but all of them, for one reason or another, are unacceptable. The solution proposed here calls for passivation of the Al surface by formation of an impervious layer of aluminum silicate and subsequent encapsulation of the powder in silica gel. The Procedure 10 gms of Al fines were mixed with 100 cc of 10% solution of sodium silicate using a high speed blender. A dilute sulfuric acid was added to lower the pH below 9.

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Passivation of Aluminum Fines

Aluminum fines resulting from turning operations of aluminum (Al) disks are explosion-prone. In the presence or absence of kerosene, the fines can be ignited by welding sparks or other sources of high temperature and subsequent efforts to extinguish the fine with water naturally have to fail due to the generation of H2 gas on contact. Various suggestions aimed at rendering the fines inactive have been proposed; but all of them, for one reason or another, are unacceptable. The solution proposed here calls for passivation of the Al surface by formation of an impervious layer of aluminum silicate and subsequent encapsulation of the powder in silica gel. The Procedure 10 gms of Al fines were mixed with 100 cc of 10% solution of sodium silicate using a high speed blender. A dilute sulfuric acid was added to lower the pH below 9. Gel was formed in seconds although the final consolidation required several hours. (Gelling can be also affected by the addition of esters, aldehydes or amides, which liberate acid as a homogeneous gelling agent.) The gelled Al fines can be safely stored wet, or they can be dried. In wet storage, no gas liberation temperature build-up was noticed over a period of one month. The dried gel was also tested for its explosiveness by placing it in a furnace at 1100OEC for one hour. There was no reaction other than a setting to a strong solid. In contrast, the untreated powder was found to be pyrophoric in temperatures i...