A New Model to Predict the Power Draw in Tumbling Mills

Peche R.V. · IMPC 2024 - 31st IMPC-International Mineral Processing Congress (2024)

Resumen

or sizing tumbling mills, the first step is to determine the specific energy according to ore breakage properties and reduction work from a known feed size to a desired product size. For this first step, specific energy models are used, then the required power draw is determined by multiplying the specific energy by the desired throughput. If the first step is miscalculated, the consequence will be a failure to reach the desired throughput and/or product size, resulting in detrimental economic results for the stakeholders. However, if the first step is well calculated, the second step is to determine the right mill dimensions and operating conditions, such as ball load, total load, and speed that will draw the required power. The specific energy determination was discussed by the author (R. Valle – IMPC 2020 & Procemin 2020) presenting a new model of variable exponent in function of feed size. This paper deals with determining the required power draw from mill dimensions and operating variables for AG, SAG and Ball Mills, to have an accurate sizing of wet tumbling mills, ensuring the objective throughput and product size of mining projects. The enhanced model to predict the power draw has been proven with 191 industrial data sets in a wide range of gross power draw, from 6 to 22,800 kW. The relative errors of predicted vs actual gross power draw have a normal distribution with a standard deviation of 4.7% for all mills AG, SAG and Ball Mills, giving a precision of +/- 9.2% with 95% confidence level. The mathematical model has the same form, regardless of mill type; the only difference between grate and overflow discharge mills is the coefficient of the model. Copyright