UBC Theses and Dissertations

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UBC Theses and Dissertations

Size classification and dewatering for fine HPGR comminution circuit Saud Soto, Cherezade Karine


High-pressure grinding roll (HPGR)-based circuits are increasingly applied to replace the semi-autogenous grinding (SAG) mill circuits due to their higher energy efficiency and lower operating cost. A novel HPGR circuit is proposed to replace conventional ball mills and extend the energy benefits for final grinding before the flotation or leaching circuit. However, the typical moisture of the ball mill feed is 20–35%, while the highest acceptable feed moisture to the HPGR is ~10%. Therefore, replacing the ball mill with HPGR technology requires a size classification and dewatering system. The purpose of this thesis was to assess the applicability of a variety of size classification and dewatering technologies to a novel HPGR comminution circuit. A ranking system was developed to identify the size classification and dewatering technologies with the most potential for the proposed circuit. The ranking matrix was developed using criteria essential for selecting equipment—with weighting factors assigned for each criterion. The ranking results for size classification equipment showed that the screw classifier scored the highest, followed by the high-frequency screens and the Derrick® Stack Sizer®. Based on the ranking results, test work was conducted to evaluate the capabilities of the selected equipment to process the material for the novel circuit. As a result, the size classification using the screen or screw obtained efficiencies of over 85%. For the dewatering equipment ranking, the dewatering screw scored the highest, followed by the pan filter and the dewatering screen. Based on the ranking results, test work was conducted with these three selected pieces of equipment. The vacuum filtration and the screw could achieve a moisture content below 10%. Therefore, both technologies were suitable for the novel circuit. With the ranking and test results, three combinations of equipment were suggested for the novel HPGR circuit for fine grinding: 1- Screens, follow by screw dewatering 2- Screws, follow by dewatering screw, and 3- Single-stage of screw classifier. The three proposed circuits could achieve the target moisture (less than 10%), but only the first to can achieve the target fine content (less than 5%).

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Attribution-NonCommercial-NoDerivatives 4.0 International