Purpose. To develop a method for complex ultrasonic measurement of such parameters of the iron ore slurry flow passing through the working chamber of the magnetic separator as efficiency, concentration and grade size distribution of solid-phase particles. Methodology. The research uses methods of modelling processes of ultrasonic wave propagation in the iron ore slurry. Ultrasonic wave absorption and scattering in water with solid particles and air bubbles are considered. To characterize absorption and scattering of acoustic oscillations by oscillating gas bubbles, concepts of effective cross-sections of attenuation, absorption and scattering are introduced. Findings. The dependence of the phase velocity of asymmetric Lamb waves on the wall thickness of the magnetic separator was obtained. As a result of computer simulation of the process of ultrasonic waves propagation, its time and frequency characteristics were obtained. Based on the data obtained using ultrasonic measurements, the coefficients of the Rozin-Rammler equation for the characteristics of the ore material at various points of the technological line were calculated. Originality. The proposed method of ultrasonic measurement of characteristics of the iron ore slurry in the working chamber of the magnetic separator differs from the existing ones in the fact that the Lamb wave source operates in a wide pattern and is connected by a V-shaped scheme which makes it possible to create a beam of coherent waves propagating both in the container wall (the working separator chamber) and in the measured medium (the iron ore slurry). Practical value. The practical value consists in developing an ultrasonic measuring channel scheme for determining characteristics of the iron ore slurry in the working chamber of the magnetic separator.
Purpose. Improvement of the method for estimating sedimentation process parameters of the slurry solid phase particles in thickener on the basis of measurements of the nonlinear characteristics of ultrasonic waves propagating in a controlled medium. Methodology. The following methods were used: analysis of scientific results and practical developments; methods of mathematical statistics for evaluating the results of experiments; methods of analytical synthesis; methods of numerical modeling for the synthesis and analysis of a mathematical model. Findings. It was established that the nonlinearity of the process of propagation of ultrasonic waves in ore slurry, which is determined by the number and size of crushed ore particles in it, can be estimated by determining the amplitudes of several harmonics of the measured acoustic signal. This approach allows maintaining the productivity of the desliming process in accordance with the characteristics of the ore suspension, without allowing the loss of valuable components. Obtaining real-time information about the characteristics of the particle sedimentation process in the ore suspension at the initial stage enables reducing the duration of transitional processes in the control system. Originality. The method for estimating the parameters of the deposition of the solid phase of the pulp in the thickener has been improved, which is based on the fact that the nonlinearity of the process of propagation of a controlled ultrasonic signal in the thickener; this leads to modulation of the generated ultrasonic packet and, consequently, the appearance of higher harmonics. To obtain a more accurate estimate of the nonlinearity of this process, all the values obtained must be normalized to represent only the relative changes in the acoustic nonlinear response. Practical value. A system for automatic control of the thickener operation is proposed, which uses nonlinear ultrasonic measurements to estimate the parameters of the sedimentation of the solid phase of the pulp in the thickener. According to the results of industrial tests of the system of automatic control of the thickener based on ultrasonic control devices, it was established that its use as part of the automated control system for the technological processes of beneficiation of iron ore raw materials at the ore beneficiation factory of the Northern mining works will allow reducing water consumption by 3.5 % and iron-magnetite losses by 0.6–0.7 %.
Thickeners are process units that are often used at mining enterprises. There, they are involved in dehydration of mineral concentration products when water is removed from wet tailings containing metal concentrates. In mineral processing, large quantities of process water are used to separate different minerals from each other, so dehydration plays a major role in ore processing and preparation for concentration. This research aims to develop methods and tools of ultrasonic measurement of characteristics of settlement of solid-phase slurry particles and to assess their possible application to the automatic control system of the thickener to improve its efficiency.
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