Structure and Evolution of Fugitive Particles from a Copper Smelter

Tetrahedrally branched particles have been observed among fugitive emissions from an Arizona copper smelter. Scanning and transmission electron microscopy, employed to investigate their structure and chemistry, has enabled us to trace their origin back to a specific stage of the copper smelting process. The particles exhibit a continuous variation in both morphology and chemical composition. This continuum of particle characteristics is subdivided into four particle types: (a) sharply profiled zinc oxide tetrahedra (fourlings) that consist of four single crystals arranged in an approximately tetrahedral array; (6) rounded, carbon-coated zinc oxide tetrahedra; (c) rounded, carbon-coated tetrahedra in which the skeletal zinc oxide core has suffered substantial decomposition; (d) well-rounded tetrahedra of carbon in which the zinc oxide cores have undergone complete decomposition. This variation in composition and morphology has enabled us to describe the evolution of the particles and to use them to identify the industrial process where they are generated and released.