Reclamation of Industrial Tailings by Means of Metallurgical Slag

In a microplot field trial, the use of crushed slag to break down the capillary borders in recultivation of toxic tailings (at enrichment facilities and solid waste dumps) with minimum application of fertile soil was studied. In this approach, metallurgical wastes may be used in low-cost energy-saving technologies. Four basic types of slag produced at AO EVRAZ ZSMK in steel smelting were studied: white nonferrous slag; blast-furnace (open-hearth) slag; electrosmelting slag; and converter slag. Such slag forms an inert layer under a minimal layer of fertile soil on trial plots, where perennials (a legume–grass mixture) were planted. For each slag, we used a control plot (without fertilizer); a plot with a potassium-humate preparation; a plot with complete mineral fertilizer; and a plot with a mixture of these approaches. At the end of the growing season, the above-ground phytomass is 17–128 g/m². The best results were obtained with converter slag and blast-furnace slag, characterized by the lowest phytoxicity. Addition of mineral fertilizer alone or in combination with potassium humate increases the phytomass by a factor of 2–4. Added alone, potassium humate had no influence on plant production but, in combination with mineral fertilizer, it increased the phytomass by a factor of 1.6–1.8. To stimulate germination and phytomass production, the addition of both mineral fertilizers and humic preparations is recommended. The converter and blast-furnace slag may be used as an inert material in reclamation, with minimum application of fertile soil. White slag and electrosmelting slag are not recommended, on account of their high phytotoxicity; in those trials, the perennials employed did not thrive.