The U.S. Department of Energy (DOE) Office of Industrial Technologies, Mining Industry of the Future Program, works with the mining industry to further the industry’s advances toward environmental and economic goals. Two of these goals are (1) responsible emission and by- product management and (2) low-cost and efficient production DOE formed an alliance with the National Mining Association to strengthen the basis for research projects conducted to benefit the mining industry. The research described in this paper resulted the collaboration between DOE and In fact, NMA and industry representatives reviewed the results of this DOE project that was conducted by Oak Ridge National
Laboratory (ORNL) and Colorado School of Mines engineers.
This paper generally describes copper, lead, and zinc mining and their associated process wastes and residues. This description can serve as a basis for identifying the process residues and waste that contain both impurities and products which currently cannot be economically recovered. This information can be used to develop a market-based approach to by-product recovery by evaluating potential revenue generated from the sale of by-products along with innovative recovery techniques. Accordingly, this paper is intended to facilitate discussions between researchers and mining company representatives to clarify by-product recovery . opportunities by providing easy-to-understand descriptions of mining processes. When by- product recovery opportunities are identified, they can be evaluated by using criteria such as favorable economics and reduced environmental impact. Collaboration between research and industry representatives can identify by-product recovery research on processing methods that promise to improve the economics of mining.
ORNL engineers evaluated copper mining operations, prepared flow diagrams of those operations, and identified process residues with by-product recovery potential (Figure 1) The United States currently holds 16% of the world’s refined copper reserves in 30 active mines. Fifteen copper mines located in Arizona, New Mexico, Utah, Michigan, and Montana
produced 99% of domestic production in 2000
The U.S. copper sector generates
metric tons per year of process
Hydrometallurgical processing is important. In 1991,
leached 15.7 million metric tons of copper ore to recover 441,000 metric tons of copper.
However, 80% of the world’s
ores with concentrations of 0.7% or less copper. These ores are treated by
pyrometallurgical methods that generate major process residue streams. Ore
sizing and froth flotation of-ore-concentrates copper tailings. Smelting concentrates copper to matte
dust, fine particles, and waste. Gas cleaning and
acid production generates sludge. Depending on processing details, each of these residues presents differing opportunities for by-product recovery.
Dust, fine particles, and tailings
Beneticiation of copper ore by sizing and froth flotation concentrates the copper while producing dust, fine particles, and tailings. Excavated ores are reduced to pulp by adding water and crushing in jaw, gyratory, and cone crushers, then sized with vibrating screens.
Pulp is ground in rod and
mills, followed by semi-dutogenous or autogenous milling