Solubility of harmful substances, leaching methodsJari Väätäinen2019-01-22T10:04:49+02:00
Solubility of harmful substances, leaching methods
Päivi M. Kauppila1 & Henna Punkkinen2, 1Geological Survey of Finland, P.O. BOX 1237, FI-70211 Kuopio, FINLAND, e-mail: paivi.kauppila(at)gtk.fi ; 2VTT Technical Research Centre of Finland, P.O. Box 1000, FI-02044 VTT, Finland
Mine wastes contain various elements and compounds that may be harmful to the environment. These compounds may be metals (e.g. Al, Cr, Cu, Fe, Mn, Mo, Pb, Ni, Zn, V), metalloids (As, Sb), salts (e.g. sulphates), nutrients (nitrogen compounds) or organic compounds. They originate in the deposit itself or from the explosives used in the excavation (nitrogen compounds), process chemicals (e.g. xanthates, cyanide, sulphur compounds, salts) or the fuels used in machines and equipment (mineral-based oils). The occurrence and concentrations of harmful metals, semimetals, sulphates and nutrients depend primarily on the geology and mineralogy of the ore deposit as well as the efficiency of the concentrating process (Kauppila et al. 2013). The leachability of potentially harmful constituents varies strongly for each waste type and each element. Therefore, leaching tests are needed to evaluate whether these elements or compounds are prone to mobilize from the mine waste (e.g. Technical Comittee 2012).
There is a wide variety of leaching tests available to evaluate leaching of potential contaminants from mine wastes. These tests range from short-term compliance tests to long-term laboratory and field tests. The most commonly used tests for mine wastes include column leaching test (CEN/TS 14405:2004), humidity cell test and sequential extractions. Field tests are currently gaining more interest and popularity, as they correspond to the actual disposal conditions of the waste but in smaller scale.