A process for the elimination and/or reconditioning of carburizing salt wastes resulting from the hardening of various steel products, including, nitrite- and nitrate-containing wastes, sometimes containing barium, and cyanide- and cyanatecontaining wastes in which the nitrite- and nitrate-containing wastes are melted at a temperature between about 120* and 400*C, the resultant melt is filtered to obtain a reusable liquid nitrite/nitrate mixture and a solid residue, an excess of the residue is mixed with a solid cyanide- and cyanate-containing waste, if the barium-containing waste is to be eliminated rather than reconditioned, a sulfate of calcium, sodium, iron or mixtures thereof is added to the mixture in an amount equivalent to the barium content, and if it is desired to prevent the formation of nitric oxides, a reducing agent, such as, fine coal, charcoal, etc., is added to the mixture, the mixture is heated to a temperature of at least 150*C for a time sufficient to cause ignition of the mixture, preferably in a thin layer on a moving belt, the ignited product is washed with water and filtered to obtain a reusable barium carbonate residue and a strongly alkaline solution containing alkali carbonate suitable for use in the preliminary clean-up of heavy metal salt-containing industrial waste waters or the neutralization of waste acids, and, if a sulfate has been added, directly discarding the ignited product as a storable refuse.