Melting noxious waste-contg. charge to produce environmentally safe useful prod. - by mixing charge except cullet and frit, delivering batchwise with indirect preheating etc.

摘要

Charge comprises (by wt.) at least about 20% recycled cullet and/or frit, about 40% polluting waste material and balance (about 40%) raw material mix of basalt chips, barytes, calcite, Li2O, TiO2 and P2O5 formulated in accordance with the waste material analysis. All the constituents, except the cullet and frit, are mixed and, like the cullet and/or frit, are delivered batchwise with indirect preheating by furnace off-gases and, after attaining the desired temp., introduced into the furnace through a closed channel at a pressure higher than that within the furnace. Furnace has stepped sections along its length and stirrer devices extending over the section widths to produce different temp. mixed streams in which homogenisation and reaction are induced, the resulting gaseous prods. escaping with the flue gases; and melt is cast and subjected, in a subsequent cooling furnace, to consolidation with at least 70% crystalline structure formation by means of its nucleating and crystallising material content at 680-720 deg.C and by means of further temp. controlled cooling, so that non-polluting, physically and chemically high grade prods. are obtd. In a material compsn. ratio of pullutants to the vitrifiable raw material mix plus additives is about 1:1 with 10% variation, the overall melt having a frit and/or cullet content of about 20%. USE/ADVANTAGE - Esp. useful for disposal of heavy metal laden filtered solid waste, e.g. filter dust from steelmaking and filter cake from special waste incineration. Can convert large amts. of noxious waste into a non-polluting prod. having a wide variety of uses e.g. in the building, chemical and electrical industries.