Cement, Energy and Environment

solution and be reprecipitated as fast as possible so that further dissolution can take place. Finer gains assist in three ways. The finer grains will generally assist with workability of concrete, providing some benefits as discussed in the last issue. They also provide a greater surface to the water for reaction and provide a larger surface for precipitation of hydration product. Figure 5 shows the effect of finer grinding on strength development irrespective of improvements in water demand because the strengths relate to mortar prisms made to a specified water content. As expected, the early strengths are improved. There is also some improvement at 28- days but less marked than the earlier results. While finer milling is universally used as a means of improving strengths when quality looks like taking a fall , the amount of extra milling required to make a significant difference at 28 days is very large. Within the normal range of the 52.5N product the variability due to fineness exceeds any benefit likely to be gained from a typical 20m 2 /kg (200 Blaine) increase, but the cost in lower output and extra power is large. To optimize strength growth it is important to optimize the C 3 S content and the fineness. This does not, however, mean to maximize both. In real concrete the provision of a cement which minimizes the water requirement needs to be matched by one which provides the mix of reaction products which will fill space, but provide stability over the long-term. Courtesy: International Cement Review, November 2009, P67-70. ENERGY EFFICIENCY & CONSERVATION Energy Security & Management COAL CONSUMTION TO CROSS 2BN TONNE BY 2030: Minister The Ministry of Coal has projected coal intake to cross 2 billion tonne by 2030, according to Coal Minister Sriprakash Jaiswal. To meet this surging demand, the industry has to adopt scientific mining practices, which, besides increasing productivity, would also cause mrnrmum damages to the environment said Jaiswal. The government is serious about bringing reforms in the coal sector to improve production , safety and the overall competitiveness of the industry, he said and stressed the industry is required to match global benchmarks in every area of its operation and establish the best practices for long-term sustainability. The overall energy mix at present is envisaged to be in the range of 52-62 per cent and 70 per cent of the country's power generation is still coal-based. Total coal demand during 11 1 h Plan (2007-12) is expected to touch 700 million tonne. To reduce the exposure of workforce to hazardous mining conditions particularly in underground mines, the government is encouraging clean coal technologies like underground coal gasification , coal-bed methane etc which are comparatively safer as persons are less directly exposed to natural hazard, he added. Courtesy: FIMI (Federation of Indian Mineral Industries) News Bulletin, Apri/15, 2010, P3. COAL INDIA TO PRODUCE 461.5 MILLION TONNES OF COAL IN FY 2011 According to London Commodity News report, CIL plans to produce 461.5 million tonnes of coal in 2010-11 against the envisaged production of 435 million tonnes in the current fiscal, a top company official said. CIL is planning a production of 461.5 million tonnes in the next fiscal and will enter into an agreement with the coal ministry the CIL official said. The country's largest coal producer is facing land acquisition problems and regulatory bottlenecks to meet its production target of the current fiscal. Coal India has market share of 80 per cent and meets major raw material requirements of domestic power, steel and cement producers. Courtesy: FIMI (Federation of Indian Mineral Industries) News Bulletin, April15, 2010, P4. ENERGY SECURITY WITH COAL - A TOUGH AND CHALLENGING PROPOSITION True, coal is currently the dominant fuel in India's energy mix. It meets more than half of the country's energy needs and fuels 78% of the electricity generation. The Government of India places great reliance on coal energy and projections indicate that this situation will prevail for the next two or three decades. The question is - why did our country get locked in a coal-dominated fuel mix? Four major factors are responsible for the situation: technology, relative cost, beliefs and perceptions, 23