Cement, Energy and Environment

linkage to any international financial instrument for emission reduction. The big cement firms in the world have joined an outfit called the Cement Sustainability Initiative (CSI), which promises to realise voluntary emissions cuts. But with demand for cement growing by around 5% annually, the industry's environmental problems are only likely to grow. The emission cuts for cement industry come in three main areas. • • First, cement-makers are trying to make their machinery more energy-efficient to reduce the amount of energy needed per unit of output. Second, they are replacing fossil fuels such as coal and coke with alternatives such as farm waste or used tyres. • Third, they are mixing more additives into their cement, and so reducing the proportion of emissions-intensive clinker. The potential of introducing energy- efficient machinery in cement plants is very high. Energy conservation is urgent need of the time due to the following reasons. Economic reasons. • To reduce cost of production. • To conserve the scarce mineral wea lth. Environmental reasons. • To reduce environmental pollution . • To utilize wastes which otherwise cause environmental degradation. • To reduce emission of Green House Gases. Liberalization and globalization has brought intense competition among producers. The competition from the global producers has made the Indian manufacturers more cost conscious now. The customers demand quality for the product and value for their money. Only the fittest would survive in such competitive market. Energy conservation is the only way for energy intensive industry like cement industry to reduce the cost of production. Indian Cement industry is the most efficient in energy usage compared to its peers in the world. Even today the America gets nearly 30% cement production from wet process kilns. China's share of cement production from highly polluting vertical shaft kilns is nearly 40% now. Until 1975 India was producing 70% of its cement production in wet kilns. India has converted almost all wet process plants into dry process now. Still India has few cement plants of old vintage and old technology. The Indian Cement industry which earlier consumed roughly 120 kwh/tonne of cement electrical energy and 1500 kcal/kg of clinker heat energy has substantially reduced to 90 kwh/tonne and 750 kcal/kg respectively. Some plants even achieve 65 kwh/tonne and 650 kcal/kg. The table below shows potential energy saving in converting old plants into modern precalcinator technology plants. Energy Saving potential in the Conversion of Wet process to Dry Process Wet process (Long Kiln) Dry process (Long Kiln) Pre-heater kiln without pre-calcinator Pre-heater kiln with Pre-calcinator 110 100 120 90 1500 1200 900 750 Energy Saving in Grinding Machinery: Grinding consumes approximately two-third of the total electrical energy used in cement-making. The table below shows different energy-efficient cement grinding machinery and their investment cost. Energy saving machinery is also capital– intensive and it is not always text book case to pick up energy-efficient machinery. Sometimes other issues like hard and highly abrasive material; quality of the product; capital requirement etc. would come in the vvay of selection of the energy– efficient machinery. Open Circuit Ball Mill Closed Circuit Ball Mill Roll press-Ball Mill Combi-grinding Roll press finish grinding Vertical roller Mill 30 33 26 25 24 Energy Saving in Preheater System: 100% 130% 160% 140% 200% Nowadays 6-stage preheater system for kiln is in vogue due to its heat-saving potential. There are many 4-stage kilns in operation which have option •