Chemical Characterization of Slags from an Old Smelter in Chihuahua, Mexico

Abstract

Slag is waste from pyrometallurgical processing, usually stored in stacks or warehouses around or near smelters. Slag research has focused on potential environmental problems associated with slag weathering or processing for secondary metal recovery and/or other uses (construction, landscaping, etc.). Located in northern Mexico, the city of Chihuahua has a mining history that dates back to the eighteenth century. A lead smelter located southeast of Chihuahua City; closed in 1997, leaving behind a large pile of slag. In this study, a chemical analysis of smelter slag was carried out. The tailings contain Zn (15 - 35 wt%), Pb (0.5 - 4 wt%), As (0.6 wt%), Sn (888 ppb) and Hg (170 ppb). XRD identified several minerals such as hardystonite (Ca2ZnSi2O7), melanotekite (), kentrolite () and sphalerite (ZnS) in the glass. Major elements are present in phases such as monticellite (CaMgSiO4), kirschsteinite (CaFe2+SiO4), hedenbergite (CaFe2+Si2O6), babingtonite (Fe2Si3O9), magnetite (Fe3O4), and calcite (CaCO3). Whether the goal is reuse, recycling or remediation, research into the properties of slag and its environmental and health impacts (on vulnerable exposed populations) should continue to be relevant.