Assessment of element mobility from copper smelting waste slag into forest soils

Abstract

Research subject. In this paper, we investigate the possibility of recycling wastes from copper smelting facilities in brown mountain forest soils. The research object was “technical sand” obtained at the Sredneuralsky copper smelter as a byproduct. This finely dispersed material rich in copper, zinc and other chalcophilic elements undergo mechanical activation during crushing of the cast slag.Materials and methods. Experiments were carried out in the southern taiga district of the Trans-Ural hilly-foothill province (Middle Urals) in autumn before snow cover. Two types of forest areas identified according to the genetic forest typology were investigated: cowberry shrub pine forest and berry pine forest with linden, both under trees and in clear-cutting areas. The experiments involved scattering 1kg of waste across 1m2 of experimental soil, packing such a sand in 100 g packages made of non-woven material and burying these packages in 3 experimental plots a depth of 7–10 cm. Following 2 years, the packages were retrieved and weighed. The microelement analysis of soil samples was carried out by the method of inductively coupled plasma mass-spectrometry using an Elan-9000 ICP mass-spectrometer at the Geoanalitik center of the Institute of Geology and Geochemistry, Ural Branch of RAS.Results. It was found that, after 2 years of residing in the soil, copper smelting waste slag loses 11% of its mass. The majority of chalcophilic elements are involved in the biogeochemical cycle. The content of zinc, arsenic, cadmium and selenium varies most signfificantly. A difference in the degree of element migration from the “technical sand” to the brown mountain forest soil was observed for 2 forest types and clear-cutting areas. A single surface application of mineral waste (1 kg/m2 ) in autumn did not affect the qualitative composition of the grassy layer of all forest types and clear-cutting areas in the following spring–summer period.Conclusion. The findings can be of interest for specialists developing new methods for recycling mineral wastes from copper smelters. Future research should analyse the distribution of components migrating from the “technical sand” along the soil profile of forest soils, as well as their involvement in biogeochemical cycles.