Abstract

Background : Cement industry has many process units. Basically all of these units can be considered as a source of noise. Since noise pollution is defined based on its offensive hearing effects, the importance of the noise sources depends directly on the number of workers in the unit. Materials and Methods : An experimental study has been done at Tehran cement factory to recognize and analyze the major noise pollution source machineries. In this survey, first, the mean A-weighted sound pressure level and the number of workers in each unit have been measured and the obtained data has been analyzed in Microsoft Excel. Afterwards, based on the mentioned ISO, some experiments have been done to calculate the A-weighted acoustic power level of the crusher which emits the highest level of noise. Results: The noisiest units have been recognized and some applicable suggestions have been offered to reduce the sound exposure level. Also by calculating the sound power levels and considering the design parameters which affect the sound power generated by the crusher, an empirical equation has been presented to calculate the acoustic power level as a function of horsepower, number of hammers and the weight of each hammer. Conclusion: The acoustic measurement results show that the crusher, cement mill and row mill units are the three major noise emission sources. In another experiment, based on ANSI S1.36 and ISO 3746 guidelines, the sound power level of the crusher unit has been measured indirectly. Afterwards, by using a multiple regression algorithm and minimizing the mean square error, an empirical equation has been proposed to correlate the acoustic power level as a function of the horsepower and the mass of all hammers of the crusher.