New Approach Study on Dry Coal Cleaning System with Two-Stage Corona Electrostatic Processes for High-Sulfur Low-Grade Fine Coals

Corona electrostatic separation can remove inorganic materials from coal, reduce coal ash content and sulfur content and improve coal quality, reduce air pollution caused by smoke dust, SOX, and COX. The performance of corona electrostatic separation technology in cleaning a middle ash medium-ash, high-sulfur coal was experimentally investigated. The electrode voltage, drum rotational speed, and feeding speed were tested, whereas other parameters were maintained constant during the experiment. The results indicate that the performance of this technology in cleaning medium-ash, high-sulfur coal can be improved by optimizing the process parameters. The results demonstrate that corona electrostatic separation is effective for the beneficiation of this grade coal. In addition, the efficiency of coal cleaning is significantly improved by adding the second stage beneficiation to clean the middlings out from the first stage beneficiation. In this study, the first stage of beneficiation recovered 38.00% (by weight) of clean coal (ash content below 20%), and the second stage recovered 48.58% (by weight) of clean coal, improving the overall separation efficiency from 0.69 to 1.74. Furthermore, the sulfur content was reduced from 4.71% (raw coal) to 3.53% (clean coal). Our result show that corona electrostatic separation can effectively reject inorganic sulfur from raw coal, and the two-stage separate is also very helpful for coal purification.

Simulation of Corona Electrostatic Separator for End-of-Life Management in Printed Circuit Boards

Printed circuit boards (PCBs) are made of several materials, including platinum, gold, silver, and rare earth elements, which are very valuable from a circular economy perspective. The PCB end of life management starts with the component removal, then the PCBs are shredded into small particles. Eventually, different separation methods are applied to the pulverized material to separate metals and non-metals. The corona electrostatic separation is one of the methods that can be used for this purpose since it is able to separate the conductive and non-conductive materials. However, the lack of knowledge to set the process parameters may affect the efficiency of the corona electrostatic separation process, ultimately resulting in the loss of valuable materials. The simulation of particle trajectory can be very helpful to identify the effective process parameters of the separation process. Thus, in this study, a simulation model to predict the particles trajectories in a belt type corona electrostatic separator is developed with the help of COMSOL Multiphysics and MATLAB software. The model simulates the particle behavior taking into account the electrostatic, gravitational, centrifugal, electric image, and air drag forces. Moreover, the predicted particles trajectories are used to analyze the effects of the roll electrode voltage, angular velocity of roll electrode, and size of the particles on the separation process.

Analysis of the Triboelectrostatic Charging Behaviour of a Synthetic Sulfidic Copper Ore

In this study, several tests were performed to analyse the triboelectrostatic charging behaviour of an artificially mixed sulfidic copper ore consisting of quartz and chalcopyrite. To check the surface charge of the pure mineral samples, they were analysed in a self-developed triboelectrostatic charging unit. After that, the artificially mixed sulfidic copper ore was sorted by using a triboelectrostatic belt separator.The objective of the study is to generate basic knowledge about the triboelectrostatic charge behaviour and furthermore the sortability by using electrostatic separation. All separation tests were carried out under controlled ambient conditions.

The Technology of Precision-selective Electrostatic Separation of Mixed Secondary Polymers

This technology of precision-selective electrostatic separation of mixed secondary polymers with pre-activation of their surfaces with surfactants for chemical destruction of surface polymer is described. A prototype of the process of precision selective separation of mixed polymer materials in the electrostatic field has been developed. Optimum operating modes of the process of activation of polymer surfaces with surfactant solutions as a preliminary stage of separation of mixed polymers in the electrostatic field are determined. An experimental prototype of a process line has been created for selective electrostatic separation chemically activated narrow-fractional mixed crushed polymer waste.