Kim Dowling

Carbon Capture and Storage

Rising oil and gas prices, insecure energy supplies, and increased energy consumption in transition economies have boosted the use of coal—the most abundant fossil fuel and one that many countries have considerable reserves of. The United States, China, and some other countries are highly dependent on coal. In the United States, coal-powered plants generate more than half the electricity, and some observers expect that expanding the use of coal will help reduce U.S. reliance on foreign oil. But coal is the most carbon-intensive fossil fuel. Thus a new technology called carbon capture and storage (CCS) has recently gained considerable attention. CCS aims to capture carbon dioxide (CO2) from any large point source, liquefy it, and store it underground. Because of its high costs and complex infrastructure, CCS is by necessity suited primarily for centralized, large-scale power stations or big industrial facilities like cement plants and steelworks. With today’s technologies, there are three ways to capture CO2. Post-combustion capture, which involves capturing CO2 from flue gases in conventional power stations, is basically available today, but it has not yet been demonstrated at a commercial power station scale. In the longer term, this technology is unlikely to become widely established unless its energy consumption can be reduced significantly. A more efficient method is pre-combustion capture of CO2 in coal-fired power stations with integrated gasification combined cycle technology. These plants use heat to gasify coal that is then burned to generate electricity. During the gasification step, CO2 can be removed relatively easily. Apart from its higher efficiency levels, the prime advantage of this method lies in its flexibility in terms of both fuel (coal, biomass, and substitute fuels) and product (electricity, hydrogen, synthetic gas, and liquid fuel). Pre-combustion capture of CO2 has not yet been demonstrated on a large scale. The so-called oxyfuel process currently offers the best prospects for CO2 capture in terms of achievable overall process efficiency as well as costs because it is largely based on conventional power station components and technology. Combustion takes place in 95 percent pure oxygen rather than air, enabling efficient CO2 capture due to the concentrated flue gas. This process is still near the beginning of its demonstration phase. It is expected to capture 99.5 percent of the emissions directly at the stack, while the post-combustion and pre-combustion methods would reduce CO2 by 88–90 percent on average.1 Carbon Capture and Storage

Sustainability in the Mineral and Energy Sectors

The mining industry has long sought a step change in productivity by integrating operations from mine to market. While there have been some success stories, in general the promise has not been delivered due to some crucial gaps in technology and systems. Many of those gaps have now been closed, or at least recognized, meaning the tools are now available to deliver the benefits of integration. THE MINING PRODUCTIVITY CHALLENGE The minerals industry faces a productivity and investment crisis. The “Millennium Super Cycle” from 2003 to 2011 was an unprecedented period of growth and investment. Throughput was increased and lower grade resources were developed to meet demand. The urgency to bring production to market quickly stretched people, project, and management resources. But the “boom” ended and prices have declined, with the industry left with a legacy of high costs, declining ore quality, and less efficient operating practices. Step changes to practice and productivity are needed to sustainably produce the minerals society needs. Groups including the Cooperative Research Centre for Optimising Resource Extraction (CRC ORE) are working with the global resources industries to reverse the trend of declining feed grade and quality through novel approaches and innovative solutions (Figures 3.1 and 3.2). TRANSFORMING MINING PRODUCTIVITY: AN INTEGRATED APPROACH CRC ORE was established in 2010 to address these productivity challenges. It is a large scale, industry-led initiative that brings together orebody knowledge, mass mining, mineral processing, * This Chapter is based on an article first published in the Australasian Institute of Mining and Metallurgy Bulletin of March 2015. CONTENTS Abstract ............................................................................................................................................27 The Mining Productivity Challenge .................................................................................................27 Transforming Mining Productivity: An Integrated Approach ..........................................................27 Closing the Gaps ..............................................................................................................................29 Measurements ..................................................................................................................................29 Heterogeneity: Friend or Foe? .........................................................................................................30 Coarse Upgrading of Ores ............................................................................................................... 31 The Need for Integrated Site Simulation .........................................................................................34 Supporting Management and Organization Systems .......................................................................34 The Time Is Right ............................................................................................................................34