Recycling von Härtesalzen. Diskussion

Supported by the,, Deutsche Bundesstiftung Umwelt, two novel aqueous processes have been developed for the recovery of waste salts containing chlorides and cyanides as well as nitrites and nitrates. After destruction of the cyanides and removal of the impurities the recovery of chlorides is carried out by selective crystallization. Nitrate salts are recovered by a reaction of nitrites, hydroxides and carbonates to nitrates, removal of the impurities and selective crystallization of the nitrates. Rather simple technologies are used in the processes. Purity of the recovered salts is 95-99.9 %. Waste salts, which until now had to be disposed off as hazardous waste, can now be re-used. The recovered salts are equivalent to standard raw materials and can be used in the production of heat treating salts.