Evidence of trace element emission during the combustion of sulfide-bearing metallurgical slags

Abstract

The present study shows the results of field and laboratory studies of trace element transfer from waste heaps of metallurgical slags (Kemerovo region, town of Belovo). Temperature anomalies were observed, with high temperatures up to 81.2 °C on the top of the heap. A visual geophysical model of the inner parts of the heap with contrasting resistivity zones was obtained using the electrical resistivity tomography (ERT) method, and quantitative characteristics were derived. Dry and frozen slag zones were characterized by resistivity of 50–500 Ohm·m. The resistivity of wet slag varied from 5 to 10 Ohm·m for slag with low humidity of 1–2 Ohm·m for slag saturated with highly mineralized solutions. The local anomaly of extremely low resistivity (0.3–0.5 Ohm·m) might be associated with a combustion centre or high pore solutions TDS. Basic major elements (Ca, Mg, K, Na, Si, and Al), metals (Cu, Zn, Pb, and Cd) and anionic elements (As, Sb, and V) were determined in gas condensates in situ. The most volatile elements were basic elements: Ca > Cu > Mg > Na > Mn > Fe, Zn. Lower concentration in the condensates was determined for Si > K > As > Sr > Al > V and Pb, Ba, La were also found. The observed mineral paragenetic sequences were primary minerals of barite-polymetallic ores and sphalerite concentrate, high-temperature minerals formed during pyrometallurgical processing and/or permanent combustion of the heap surface, efflorescence minerals formed by atmospheric oxidation accelerated by acid steam condensation. An experimental investigations using stepwise and 500 °C heating of the same samples were performed to compare the elements that were released into the gas phase in situ and off-site.