Clean Chloride Hydrometallurgical Technologies

To have a clean sky over smelters we pay with overproduction of sulphuric acid, the further use of which contaminates waters. Technologies based on recyclable hydrochloric acid and its salts are proposed as a subject for consortium.

Reprocessing of sulphur dioxide into sulphuric acid was seen as an ecological victory of smelting technologies which recover metals from their sulphide deposits. About one tonne of sulphuric acid is generated per one ton of produced copper, zinc, nickel or other metal. In Europe about half of this acid is consumed for phosphoric acid and phosphate fertilizers production after which its transforms into ecologically acceptable gypsum. However, in prevailing number of other acid applications, also for metals recovery from ores, a significant amount of soluble in water sulphates retains in drains directed to rivers and other aquatic land resources. Of course, nor magnesium, nor sodium or potassium sulphates are toxic and 0.25kg sulphate ion per one cubic meter of water is today permissible in Europe. However, in spite of this, an ecological treat related to the current overproduction of sulphuric acid in Europe seems to be evident [1]. Just so, so-called "chloride hydrometallurgical technologies" [2] in which elemental sulphur and not sulphuric acid would be generated from metal-sulphide ores, should substitute traditional smelting processes. Hydrochloric acid and their salts are better acceptable by nature than sulphuric acid and sulphates. The European knowledge in the "chloride metallurgy" is the World knowledge. A European consortium taking advantage of this, just from ecological point of view, is proposed.,[1] F. Letowski, "Clean sky or ecological misleding in metallurgy" (in Polish), Pr.Nauk.Inst.Gorn.Politechniki Wroclawskiej, 95,konf.31,pp.37-46,2001,[2] E.Peek G.Van Weert (Editors), "Chloride Metallurgy 2002" ,CIM, Montreal, Que., Canada, 2002