Cement, Energy and Environment

and to save non-renewable resources . • In terms of waste management the cement industry contributes to conventional disposal of waste, usually directed to waste incinerators or in landfills, reducing the waste disposal problems and maximizing the recovery of energy. It has been widely proven that thermal utilization in cement kilns has many advantages in terms of savings (both economical and of raw material) and in terms of environmental conservation as well, both in an absolute sense and in comparison with traditional incinerators. From an ecological point of view, kiln emissions remain rather unchanged in quantity, but there is a lower C0 2 concentration . The emissions of a dedicated incineration kiln are next to zero. By working with the maximum capacity that is granted by law (equal to 40 per cent of the total necessary power), a fossil coal saving of 1.7Mta can be achieved. The reuse of it in cement kilns produces neither solid waste, slags or liquids nor any other problem associated with their elimination, unlike conventional incineratt.~, s. Moreover, the continuous control that the cement plant has to undergo guarantees safer recycling practices. It is important to point out that the use of these residues in cement kilns do not alter the cement composition or the quality of the final product and remains completely eco– compatible without jeopardizing human health. The interest of cement factories in improving the use of cement kilns for waste elimination is even strengthened by other elements: the regular distribution of the cement factories in the country, the costs of adapting cement factories kilns to the thermal utilization system are high but still more competitive than the necessary investments for a new incinerator plant, the present existence of plants for ashes elimination makes cement factories a potential resource to deal with the challenge of waste elimination and environment preservation. Using waste as fuel Alternative fuels are frequently prepared and blended outside the cement plant by specialized companies specifically for this purpose. Waste materials which are generally reusable as Refuse Derived Fuel (RDF) include tyres, rubber, paper, textiles, exhausted oils, wood, plastics, industrial waste, hazardous waste and solid urban waste. Cement kilns are required to have an homogeneous RDF composition which is uniform not only in shape and size but also in calorific value. In terms of uniform size, it is generally required that waste has to go through an adequate process of size reduction to make them reusable as a quality RDF. The material has to be uniform in size to facilitate its transportation and in many cases must be selected by a screen to obtain the optimal final size for the kilns depending on the feeding location. In terms of uniform heating value, it is important to guarantee an homogenous composition of waste allowing the material to burn releasing the same constant quantity of heat. It is therefore important to blend the different material types before the size reduction process or when the final material is in a pit. Recycling equipment Satrind SpA, has been involved in solving recycling , waste reduction and material handling problems for several worldwide cement companies. Satrind has developed and supplied to large international cement groups, solutions for processing different types of waste (such as industrial waste, hazardous waste , tyres, municipal waste) turning them into valuable RDF for cement kilns. To obtain an homogeneous RDF composition in terms of shape and calorific value, many competitors' solutions require to prepare and select the waste to be shredded prior to the size reduction process. The preparation of the material is necessary, when shredding heterogeneous waste, 66 --