MONITORING JAW CRUSHING PARAMETERS VIA VIBRATION SIGNAL MEASUREMENT

Fine crushing tests were performed on a laboratory scale jaw crusher w ith dry, monosize dolomite. The source vibration signal was picked up by an accelerometer, the acceleration signal was amplified by a vibrom eter, and then stored on a DAT recorder during whole testing period. F or each crushing test, three vibration signal samples were taken and c onverted into an IBM PC accessible data format using a digital oscillo scope. The digitised vibration signal was analysed with the aid of dig ital signal processing technique. Through spectral inspection and prin cipal component analysis, it was found that two major frequency bands, 250-400 and 700-900 Hz, were strongly related with the variation of t he operating parameters. The first four principal components account f or 91% of the total variation of the vibration signal. It was found th at the inter-particle collision and attrition without breakage mainly affects the energy of the 250-400 Hz frequency band, and the variation of the frequency band of 700-900 Hz characterises the breakage events of dolomite. With the aid of the multivariate data analysis, the rela tionship was established between the power spectral density and the op erating parameters such as the feed rate to the crusher, the close sid e crusher setting and the charge volume of dolomite in the crusher cha mber. The product size distribution described by Gaudin equation was a lso related to the vibration signal. Thus, an alternative method for m onitoring the operating state can therefore be developed through measu ring and processing the vibration signal from crushing.