Avaliação das diferenças entre bolas forjadas e bolas fundidas no processo de moagem

Abstract

The differences in grinding capacity and wear between cast iron balls and forged steel balls was investigated based on grinding efficiency and wear experiments conducted in a mill with dimensions 0.3048m x 0.3048. The sample utilized, designated as concentrator feed, presented d50 of 210m and grades of 45.49% Fe and 32.05% SiO2. Three sets of grinding efficiency experiments were conducted for each ball type, the difference consisting in the composition of the balls charge. The wear experiments lasted for twenty hours and one single balls diameter was utilized. The forged steel balls presented higher energy efficiency, for the same processed weight the product of the mill operating with forged steel balls was finer. The energy efficiency was from 5 to 10% higher than that of the cast iron balls. The forged steel balls presented degree of wear 30% lower than that of cast iron balls. This significant difference is due to the severe wear of cast iron balls during the first five hours of testing, due to the surface porosity, inherent to the manufacture process. The results of this thesis will contribute to decisions and also in the negotiations with grinding media suppliers, aiming at costs reduction and enhanced operation efficiency.