Noise Reduction in New Open-cut Coal Mines, Coal Handling and Preparation Plants

Noise emission from coal handling and preparation plants continues to be an important issue in Australia, with increasingly stringent legislation and environmental constraints being imposed on plant construction and operation. In recent times plant designers have endeavoured to obtain practical data to assist in the design of plants with reduced noise levels. A plant designed and built recently in the Hunter Valley of Australia, for Bengalla Mining Company, was the subject of very stringent requirements for noise emission, and a detailed sound emission analysis was carried out prior to completion of the design and construction. Noise models were produced to examine the anticipated levels of noise emission, and to assist in predicting the effects of various measures incorporated into the plant design to reduce generated noise levels. This paper discusses the various sources of noise associated with a coal mine and processing plant and the measures designed to minimise the noise. The plant has now been commissioned and has been operating for some time. Actual results from surveys during plant operation are compared with the predictions, and reasons for variations are discussed. In general, noise levels were found to match the predictions, however in certain areas discrepancies were encountered. In particular, noise associated with conveyors and bins was found to be higher than expected and several contributing factors were identified, including idler tolerances and belt surface finish for conveyors, and lining and fill level for bins. The paper details how these factors were identified, and the steps implemented to overcome them, together with typical readings before and after the rectifications.