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Investigation of laboratory conditions effect on prediction accuracy of size distribution of industrial ball mill discharge by using a perfect mixing model. A case study: Ozdogu copper-molybdenum plant

Gharehgheshlagh H. H., Ergun L., Chehreghani S.

Physicochemical Problems of Mineral Processing

2017

Vol. 53, iss. 2

1175--1187

In this study, the perfect mixing model was used to investigate its accuracy level, under different laboratory conditions, in predicting the particle size distribution of industrial ball mills discharges. For this purpose, data sets of two laboratory ball mills with eight different compositions of balls and two industrial mills of a copper processing plant for seven different tonnages, which totally included 56 simulation operations, were used. For simulation, the necessary data were obtained through performing the breakage distribution function and kinetic grinding tests using laboratory mills. The results were used to determine the first order grinding kinetics and normalized breakage rate parameters. For the industrial scale, the simulation process was carried out using data, perfect mixing model equations and JKSimMet software. The results showed that the operating conditions of the laboratory mills were quite affected by the predictive power of the desired model. Comparing the measured and simulated values of P80, it is clear that 2 minutes of first order grinding using the Bond laboratory ball mill with standard operating conditions and single size ball load of 20 mm provided the best prediction with trivial errors, less than 10%, for all seven tonnages of the industrial mills. The results of this study together with more investigations on different plants can be helpful in optimization, simulation and scale-up procedures of ball mills.

Kinetic grinding test approach to estimate the ball mill work index

Gharehgheshlagh H. H.

Physicochemical Problems of Mineral Processing

2016

Vol. 52, iss. 1

342--352

The standard Bond method is the most acceptable method for designing and selecting ball/rod mills described by their basic parameter called work index (Wi). The standard Bond method is a tedious time consuming procedure requiring at least 7 – 10 grinding cycles, so that many researchers have tried to simplify this method to be able to perform a rapid calculation of a work index. This study aims to develop a new approach toward estimating the Bond ball mill work index (BBWI) by applying a series of kinetic grinding tests with Bond standard mill. Establishing a series of relationships between grinding parameters and Bond equation parameters, this approach is fast and practical due to eliminating laboratory control steps while reducing the number of milling steps. In this scope, thirteen ore samples were used to compare Wi values obtained by standard Bond method with those of the proposed kinetic approach. The kinetic periods were determined as 0.33, 1, 2, 4 and 8 minutes. The results of kinetic tests were found to be logical and acceptable as they were so close to the values obtained by Bond standard method, for all samples error was ≤ 2.60%. It was therefore concluded that the proposed approach could be considered as a simple yet practical alternative for the standard Bond method.