COST REDUCTION THROUGH APPLICATION OF ADVANCED TECHNOLOGY

<正>There are two different ways of reducing production cost. One is the efficiency improvement of existing plant with minor modifications, when necessary, based on thorough diagnosis of existing operation. Another way is modernization of the plant by replacing of operating equipment to a equipment with much higher efficiency. The former way is sometimes more economical under certain limited conditions even though the attainable effectiveness may be less than the latter way. In this article, results of application of advanced technology developed by Onoda Cement Co., are described. Coal firing, especially low grade coal firing Is a matter of great interest to cement producer. Onoda Cement had conducted operation to clarify the effect in changing heat value of coal for four levels from 6,700 kcal/kg coal to 4,500 kcal/kg coal by using a 1,700 t/d RSP kiln in Onoda Works. It was confirmed that operation was very smooth and satisfactorily high quality clinker was produced in each level abovementioned under similar production and heat consumption. The use of low volatile matter coal as well as the use of waste fuel have contributed to cost reduction. Cement producers in many countries are now focussing their interest towards the roller mill for finish grinding as a powerful tool for power savings. Further to the development of high efficiency air separator O-SEPA, Onoda Cement has developed a roller mill named OK roller mill for finish grinding. It consumes about 20?0% less power for normal portland cement grinding than modern ball mill system in addition to about 30% lower maintenance cost. As the results of her energy saving efforts, Onoda has achieved about 20% reduction of energy per ton of cement during the past five years.