A Numerical Based Approach to Calculate Ore Dilution Rates Using Rolling Resistance Model and Upside-Down Drop Shape The
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ORIGINAL PAPER
A Numerical Based Approach to Calculate Ore Dilution Rates Using Rolling Resistance Model and Upside‑Down Drop Shape Theory Hao Sun1,2 · Aibing Jin1,2 · Davide Elmo3 · Yongtao Gao1,2 · Shunchuan Wu1,2,4 Received: 16 February 2019 / Accepted: 17 June 2020 © Springer-Verlag GmbH Austria, part of Springer Nature 2020
Abstract The chief characteristic of the caving mining method is that caved ores, surrounded by overlying rocks, are drawn from the drawpoint. And the ultimate objective of investigating the draw problems is to forecast the ore loss and dilution. In this paper, the rolling resistance model in the Particle Flow Code was used to simulate the effect of actual shape of different materials flowing towards a drawpoint under the near-field condition and improve the computational efficiency at the same time. The reliability of the rolling resistance model was validated against experimental results, and the new empirical equations were deduced for calculation of the ore dilution rates based on the upside-down drop shape theory (UDDS theory). Within the precision and range of values considered in this paper, the results show that when the height of IEZ is in the range of 30–80 m, the particle size, the drawpoint size and the column height have no significant influence on the (isolated extraction zone) IEZ’s shape and maximal width. And regardless of near-field gravity flow with one or two granular materials, the shape of IEZ was coincident with the upside-down drop shape. Keywords Cave mining method · Gravity flow · Model draw experiment · Rolling resistance model · Upside-down drop shape theory · Empirical equation of dilution rate
1 Introduction Block caving is an underground mass mining method used to recover low-grade deposits that may otherwise be uneconomical to recover (Brown 2003). A fundamental understanding of the gravity flow or flow characteristics of caved rock and rock within block caves can assist in developing strategies for the optimization of recovery from caving mines. The gravity flow is the process by which the broken * Aibing Jin [email protected] * Shunchuan Wu [email protected] 1
Key Laboratory of Ministry for Efficient Mining and Safety of Metal Mines, University of Science and Technology Beijing, Beijing, China
2
School of Civil and Resource Engineering, University of Science and Technology Beijing, Beijing, China
3
Norman B. Keevil Institute of Mining Engineering, University of British Columbia, Vancouver, Canada
4
Faculty of Land Resource Engineering, Kunming University of Science and Technology, Kunming, China
rock moves from its in situ location towards drawpoints in the production level. In practice, gravity flow has a direct impact on recovery and dilution content and, therefore, is important in determining optimal production level designs and draw control practices (Castro 2006). Predictive tools for gravity flow are often based upon test-scale physical models or mine-scale numerical simulations. Current understanding of gravity flow
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