Estimates of Electricity Requirements for the Recovery of Mineral Commodities, with Examples Applied to Sub-Saharan Africa Open-File Report 2011–1253 U.S. Department of the Interior U.S. Geological Survey Cover. High voltage power lines over the San Andreas Fault at Cajon Pass, California. Photograph by Don Becker, U.S. Geological Survey. Estimates of Electricity Requirements for the Recovery of Mineral Commodities, with Examples Applied to Sub-Saharan Africa By Donald I. Bleiwas Open-File Report 2011–1253 U.S. Department of the Interior U.S. Geological Survey U.S. Department of the Interior KEN SALAZAR, Secretary U.S. Geological Survey Marcia K. McNutt, Director U.S. Geological Survey, Reston, Virginia: 2011 For more information on the USGS—the Federal source for science about the Earth, its natural and living resources, natural hazards, and the environment—visit http://www.usgs.gov or call 1–888–ASK– USGS For an overview of USGS information products, including maps, imagery, and publications, visit http://www.usgs.gov/pubprod Any use of trade, product, or names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this report is in the public domain, permission must be secured from the individual copyright owners to reproduce any copyrighted materials contained within this report. Suggested citation: Bleiwas, D.I., 2011, Estimates of electricity requirements for the recovery of mineral commodities, with examples applied to sub-Saharan Africa: U.S. Geological Survey Open-File Report 2011–1253, 100 p. ii Contents Introduction .................................................................................................................................................................... 1 Analytical Applications of Electricity Consumption Estimates ........................................................................................ 1 Limitations on Use of Estimates .................................................................................................................................... 2 References .................................................................................................................................................................... 4 Examples of an Application of Electricity Consumption Data ......................................................................................... 7 Electricity Production in Sub-Saharan Africa .............................................................................................................. 7 Electricity Requirements for Selected Mineral Prospects Anticipated to Start Production by 2019 ...........................10 South Africa ...........................................................................................................................................................10 Ghana ...................................................................................................................................................................11 Appendix 1. Electricity Requirements for the Production of Selected Mineral Commodities .........................................21 Figures Figure 1. Map showing Eskom’s southern Africa power grid map for fiscal year 2010 .............................................. 9 Figure 2. Estimated distribution of 26 TWh of electricity consumption during 2005 among selected mineral commodity industries in South Africa............................................................................................10 Appendix Figures Figure 3. Large electrically-driven ball mills used for grinding ore to a size suitable as feedstock to the flotation cells .............................................................................................................................................27 Figure 4. Ground ore is directed to a series of froth flotation cells in which hydrophobic copper sulfides and other minerals attach to bubbles where they form a froth that is skimmed off ....................................28 Figure 5. Copper anode arrives at a refinery for electrorefining ...............................................................................41 Figure 6. Photograph of electrolytic cells in a copper refinery ..................................................................................42 Figure 7. A photograph of the Cripple Creek & Victor Mining Company’s open-pit gold operation in Cripple Creek, Colorado, showing a fairly typical heap leach gold operation ............................................55 Figure 8. A photograph of an electric rope shovel of the type used in large open pit mines .....................................81 Figure 9. A segment of an 8 kilometer-long electrically-driven conveyor belt used to transport ore from the in-pit crusher at the Bingham Canyon Mine to the Copperton beneficiation plant in Utah, USA...........................................................................................................................................................82 Tables Table 1. Estimated efficiencies for the conversion of selected fossil fuels to electricity ........................................... 6 Table 2. A compilation of estimated net generation of electricity in gigawatt hours for selected sub- Saharan African countries in 2008 ............................................................................................................11 Table 3. Number of sites and estimated annual electricity consumption for mines and facilities considered likely to come into production by 2019 in countries comprising sub-Saharan Africa ...............13 Table 4. Electricity consumption estimate for mining and processing bauxite for export in Ghana .........................15 Table 5. Estimated unit and annual electricity consumption for an alumina-aluminum facility in Ghana .................16 Table 6. Estimated electricity requirements for selected operating and prospective gold operations in Ghana .......................................................................................................................................................18 iii Appendix Tables Table 7. (A) Generalized electricity requirements for mining and producing aggregate ..........................................21 Table 7. (B) Generalized electricity requirements for mining and processing unconsolidated sand and gravel for construction ...............................................................................................................................22 Table 7. (C) Estimated electricity requirements for the production of aluminum from bauxite ore...........................24 Table 8. Estimated electricity requirements for production of ore from a multi-million t/yr block-caving operation with an underground cone crusher and a 10-mile conveyor belt to the beneficiation plant that produces one concentrate by flotation .......................................................................................26 Table 9. Estimated electricity requirements for cement production .........................................................................29 Table 10. Estimated electricity requirements for the production of chromite ore products (lump, chip, and fines of chemical, metallurgical, and foundry grade chromite) from underground room and pillar mining and gravity beneficiation ................................................................................................................31 Table 11. Estimated electricity requirements for the production of coal ....................................................................32 Table 12. Estimated electricity requirements for the recovery of cobalt cathode from intermediate products from primary and secondary feedstock by electrowinning in chloride and sulfate media ........................................................................................................................................................35 Table 13. Generalized electricity requirements for mining and heap leaching copper oxide ores .............................36 Table 14. Estimated electricity requirements for mining, beneficiation, smelting, and refining for copper oxide ores and sulfide ores .......................................................................................................................38 Table 15. Generalized electricity requirements for mining and processing diamondiferous kimberlitic and lamprolitic pipes (weathered and fresh) from selected open pit mines ......................................................43 Table 16. Generalized electricity requirements for recovering diamonds from alluvial and colluvial deposits .....................................................................................................................................................44 Table 17. Estimated electricity requirements for production of ore from a polymetallic ore body producing two base-metal concentrates ....................................................................................................................45 Table 18. Estimated electricity requirements for producing selected types of common ferroalloys ...........................46 Table 19. Electricity requirement for the production of charge-grade ferrochrome and electrolysis of chromium metal in a solution of sulfuric acid .............................................................................................48 Table 20. Estimated electricity requirements for the mining and production of gold using carbon