PHYSICAL AND CHEMICAL PROPERTIES OF CLAY-RICH MINE TAILINGS FROM TONOPAH, NEVADA; EVALUATING RECYCLING POTENTIAL
Tonopah NV has a history of mining dating back to 1900, where a small town of 40 people grew to a population of over 3,000 within 2 years of the discovery of Ag ore. Major mining operations were conducted from 1901 to 1947, with major commodities in Au and Ag, lesser in Pb and Cu, and minor W and As. In total the Tonopah mines produced >5 million tons of ore worth ~$150 million, >$1 billion in today’s market equivalent, with peak production occurring from 1901–1921 where the mines earned $121 million. Ores were milled and processed through cyanide heap leaching, following which a waste stream produced stratified deposits of clay rich tailings.
15 samples were systematically collected from two of these stratified deposits, in addition to two bulk representative samples. The deposits outcrop as a small cliff 2-2.5m high with interbedded units of clay-sandy material, mostly 2.5Y 8/3 or 6/3 in color, with a few cobble stringers present 10YR 6/2. A detailed analysis of the mine waste including mineralogical, chemical, and physical characteristics aims to provide insight into these materials and their potential for recycling. X-Ray diffraction (XRD) will be used for major mineralogical analysis and scanning electron microscopy (SEM) will be used for textural/chemical characterization. Preliminary SEM results indicate the presence of pyrite and barite consistent throughout all 15 units. Pyrite generally forms cubes from ~80-100 µm in size, and barite forms elongated-irregular crystals from ~20-100 µm. Further characteristic analysis will determine the potential of recovery, recycling, or reuse for these deposits.