Study On Particle Size Measurement And Concentration Characterization For Mineral Slurry By Ultrasonic Techniques

Compared with other particle size measurement methods, ultrasonic technique is given more and more attention for its advantages, for example, extremely wide size range of particles, its good adaptability to the on-line measurement and high concentration condition. Using ultrasonic technique in mineral production process can improve production quality and reduce production cost. But the technique develops slowly in our country. The measuring accuracy, the measuring range and the adaptability of theoretical model for ultrasonic particle size measurement have many limitations. For these problems, based on the research about the propagation features and the attenuation characteristics of ultrasound, the adaptability of several theoretical models is comparative analyzed; base on the simulation analysis of the attenuation law, a theory of composite model using linear superposition method is proposed; the hardware configuration of ultrasonic measurement system is designed, and experimental results shows well. The main contents are represented as follows:Firstly, the physical characteristics and propagation features of ultrasound are analyzed. In order to study the attenuation theory of ultrasound in solid-liquid two-phase flow, the sound velocity, sound pressure and sound intensity are researched, and the propagation feature of ultrasound both in homogeneous and inhomogeneous medium is analyzedSecondly, the adaptability of existing theoretical model for ultrasonic particle size measurement is comparative analyzed. In order to expand the adaptability of models, based on the research about the model parameters and the granular systems for model building, a theory of composite model using linear superposition method is proposed. And the correlation of attenuation with frequency of sound, concentration of particle and temperature of medium is simulated by Matlab.Thirdly, base on the velocity measurement method using transit time of ultrasound in solid-liquid two-phase flow, the hardware configuration of ultrasonic measurement system is designed. In addition, the velocity and the attenuation can be measured at the same time. The system consists of ultrasonic emission/receiver circuit, measurement case, data collection system, software system and so on.Finally, the experiments for attenuation and velocity measurement of ultrasound are conducted by single variable method, and the experimental results are consistent with the theoretical analysis. Base on the experimental data, the particle size is calculated by nonlinear inversion algorithm, and the experimental results show that the composite model has much wider adaptability and higher accuracy than the single model in quartzite slurry of which the mass concentration is 10%~50%.