Coke quality effect on the grinding in an air swept ball mill circuit

Petroleum coke fines have been produced under varying operating conditions from four petrol coke qualities in an air swept computer controlled ball mill circuit with an online particle size analyzer. The aim of the work is to show how the coke quality influences the grinding process and the product quality. Enhanced awareness on the paste plant's ball mill operation and control is increasingly important in a petrol coke market characterized by scarcity of stable single source coke qualities. The use of coke blends (up to 20 sources in one cargo) is common. The paper presents results obtained from the fines production with the following variables; different product size, air sweeping velocity/particle residence time in the mill, circulating load, mill throughput and specific energy consumption. The circulating load and air sweeping velocity/particle residence time has a critical effect on the particle size distribution steepness although the same top size product is produced. Morphology analyses show that the product particle shape depends on the process control and the energy used for fines production.