is usually from about 400 u00b0 c to about 1500 u00b0 c and more preferably from about 600 u00b0 c to about 1400 u00b0 c for an unseeded sol gel alumina the hot zone is preferably maintained at a temperature of from about 400 u00b0 c to about 1650 u00b0 c and more preferably from about 600 u00b0 c to about 1550 u00b0 c the particles obtained by the explosive comminution process of the invention tend to have pronounced aspect ratios that is they have one dimension that is substantially longer than any other such particles are particularly useful in coated abrasive applications the process of the invention is applicable to all types of sol gel particle production particularly where these are intended for abrasive applications the sol gel can be seeded or unseeded the only difference in the conditions used is that a higher sintering temperature is generally required when the sol gel is unseeded because the process of the invention permits the elimination of the physical comminution stage typical of the prior art the dried gel can be fed directly into the furnace from the drier this saves considerable time and energy costs the process of the present invention is now described with particular reference to the firing of a seeded sol gel alumina in a rotary furnace these examples are for the sake of illustration only and are intended to imply no essential limitations on the essential scope of the invention a ross mixer was charged with 74 657 gm of deionized water.