A Review of Sensor-Based Sorting in Mineral Processing: The Potential Benefits of Sensor Fusion

Published: 27 October 2022Sensor-based sorting techniques offer the potential to improve ore grades and reduce the amount of waste material processed. Previous studies show that sensor-based sorting can reduce energy, water and reagent consumption and fine waste production by discarding waste prior to further processing. In this literature review, recent investigations of sensor-based sorting and the fundamental mechanisms of the main sorting techniques are evaluated to inform optimal sensor selection. Additionally, the fusing of data from multiple sensing techniques to improve characterization of the sensed material and hence sorting capability is investigated. It was found that the key to effective implementation of sensor-based sorting is the selection of a sensing technique which can sense a characteristic capable of separating ore from waste with a sampling distribution sufficient for the considered sorting method. Classes of potential sensor fusion sorting applications in mineral processing are proposed and illustrated with example cases. It was also determined that the main holdup for implementing sensor fusion is a lack of correlatable data on the response of multiple sensing techniques for the same ore sample. A combined approach of experimental testing supplemented by simulations is proposed to provide data to enable the evaluation and development of sensor fusion techniques.Dylan Peukert, Chaoshui Xu and Peter Dow

A numerical sensitivity study -The effectiveness of RFID-based ore tracking through a simulated coarse ore stockpile and the impacts of key process variables

Available online 24 August 2023The ability to understand ore characteristics in real-time during mining processes is vital for ensuring product quality control. However, it is challenging to continuously track ore flow from the mine to the mill due to the blending of ore batches, especially within stockpiles. This paper presents a numerical study of copper ore tracking through a coarse ore stockpile. A discrete element model of a 3D stockpile was created using the EDEM software to evaluate the effectiveness of using RFID tags for ore tracking. To identify the primary variables and their effect on ore transport and tracking through the stockpile, a sensitivity study was conducted to investigate a range of process variables, such as ore size distribution, ore size range, RFID tag size, wall friction, the trajectory of charging particles and stockpile charging methods. The results show that the stockpile model is not sensitive to variables such as the ore size distribution, ore size range and RFID tag size, while wall friction, stockpile feed belt speed, segregation in the ore flow region and contact model have a significant effect on ore blending within the stockpile. It was found that the overall performance of RFID-based ore tracking through the stockpile is poor. For cases with only one or a few tags per ore batch the order in which the tags are read did not provide a good representation of the ore distribution for most scenarios This sensitivity study provides insights into new tracking strategies given the poor performance of RFID tracking shown by the simulation study.Juan Chen, Tien-Fu Lu, Dylan Peukert, Peter Dow

Translational and rotational diffusion coefficients in nanofluids from polarized dynamic light scattering

Nanofluids representing nanometer-sized solid particles dispersed in liquids are of interest in many fields of process and energy engineering, e.g., heat transfer, catalysis, and the design of functionalized materials [1]. The physical, chemical, optical, and electronic properties of nanofluids are strongly driven by the size, shape, surface potential, and concentration of the nanoparticles. For the analysis of diffusive processes in nanofluids allowing access to, e.g., particle size and its distribution, dynamic light scattering (DLS) is the state-of-the-art technique. It is based on the analysis of microscopic fluctuations originating from the random thermal movement of particles in the continuous liquid phase at macroscopic thermodynamic equilibrium. For anisotropic particles or particle aggregates, besides translational diffusion also rotational diffusion occurs. To obtain the sum of the orientation-averaged translational (DT) and rotational (DR) diffusivities by depolarized DLS [2], a homodyne detection scheme is usually applied which can hardly be fulfilled in the experimental realization. Furthermore, the experiments are restricted to limited ranges for temperature, particle concentration, and viscosity

Spatial variation in soil properties and diffuse losses between and within grassland fields with similar short-term management

One of the major challenges for agriculture is to understand the effects of agricultural practices on soil properties and diffuse pollution, to support practical farm-scale land management. Three conventionally managed grassland fields with similar short-term management, but different ploughing histories, were studied on a long-term research platform: the North Wyke Farm Platform. The aims were to (i) quantify the between-field and within-field spatial variation in soil properties by geostatistical analysis, (ii) understand the effects of soil condition (in terms of nitrogen, phosphorus and carbon contents) on the quality of discharge water and (iii) establish robust baseline data before the implementation of various grassland management scenarios. Although the fields sampled had experienced the same land use and similar management for at least 6 years, there were differences in their mean soil properties. They showed different patterns of soil spatial variation and different rates of diffuse nutrient losses to water. The oldest permanent pasture field had the largest soil macronutrient concentrations and the greatest diffuse nutrient losses. We show that management histories affect soil properties and diffuse losses. Potential gains in herbage yield or benefits in water quality might be achieved by characterizing every field or by area-specific management within fields (a form of precision agriculture for grasslands). Permanent pasture per se cannot be considered a mitigation measure for diffuse pollution. The between-and within-field soil spatial variation emphasizes the importance of baseline characterization and will enable the reliable identification of any effects of future management change on the Farm Platform