Analysis of rock fragmentation and its effect on gravity flow at the Kiruna sublevel caving mine. The final output is a block model containing both in-situ grade and diluted grade for all blocks based on planned extraction ratios for each ring on each level. Loading procedure and draw control in LKAB’s sublevel caving mines: The three main principles guiding the growth of IMZ are porosity, collapse, and erosion Pierce, Drawpoint monitoring systems can be divided into three types based on the technique used.
A high hang-up is difficult to manipulate using the LHD bucket, but a low hang-up can often be resolved. Based on the literature review and our baseline mapping study, we propose the following guidelines for a new draw control strategy: Like Malmberget, Kiirunavaara is constrained by seismicity and blasting. The Malmberget and Kiirunavaara mines are the two largest underground iron ore operations in the world. In caving operations, the draw control regulates loading by providing information on when to stop loading Shekhar, Gustafson, and Schunnesson, The draw control factor is based on the variation in tonnage from working drawpoints. In general, loading is stopped when all three loading criteria are fulfilled, but closing the drawpoints is a subjective decision and depends on the assessment of the loading personnel.
A new opening is made, the next set of production rings is drilled and blasted, and loading is continued. Orepass availability is another mine constraint that affects production scheduling. Loading criteria The loading criterion In the Kiirunavaara mine is the extraction ratio, which is the ratio of the total tonnage of material loaded from the mastwr to the estimated tonnage of the ring.
Loading near ore boundaries: Loading constraints The Kiirunavaara mine produced around However, there is an opportunity to create a new draw control strategy using the above guidelines. It took only hours to completely analyse more than 2 million draw strategies over the SLC footprint Jamieson, A load cell placed on the hydraulic cylinder of the load haul dump LHD bucket reads the hydraulic pressure in the cylinder and converts it into tonnage.
A model for gravity flow of fragmented rock in block caving mines. The draw control factor is based on the variation in tonnage from working drawpoints.
More recently, bulk sampling has been done at Perseverance mine, albeit on lkah occasions Booth et al. Dilution is given a grade which is an average of the top cave material grade and the grade of unrecovered material from the above levels Bull and Page, The initial inflow of waste is neglected, and extraction ratio targets for these rings are kept higher to recover ore that may have accumulated in the upper part of the rings. PFC3D modelling of flow behaviour in sublevel caving. This prediction is used for grade forecasting and production scheduling.
Doctoral thesis, University of Queensland, Australia. Study of the influence of interactive draw upon drawpoint spacing in block and sublevel caving mines. A study of isolated draw zones in block caving mines by means of a large 3D physical model. Malmberget mine has slightly more flexible loading criteria and uses both extraction ratio and trend of bucket grade as the primary input information.
Draw control optimization in the context of production scheduling.
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However, for certain cases such as diamond mining, sampling is difficult and ‘observational’ assessments of dilution are required or other indicators for drawpoint monitoring should be created. Guidelines for designing a new draw control strategy. Because of this, the loading procedure for these rings is different.
If ghesis loading at drawpoints in active seismic areas is not safe, the mining sequence is changed by halting the loading process in these areas or postponing blasting until the situation is stabilized. In the initial mining sequence in a mining level at Kiirunavaara, the cave front is kept flat; i.
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Loading criteria are a set of rules and guidelines that control the loading and lakb of drawpoints in SLC. Based on the literature review and our baseline mapping study, we propose the following guidelines for a new draw control strategy: The mining sequence is also changed if mining-induced seismicity occurs.
Introduction A consistent issue in sublevel caving SLC operations is the regulation of loading at the drawpoints, especially theiss the decision to stop loading from a particular drawpoint and blast the next ring is irreversible.
A new mine planning tool for sublevel caving mines. This is a separate process; it assumes that heavy finer ore flows faster than caved material Kvapil, and accumulates at the bottom of the caved material. Tonnage-based draw control strategy.
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The model was calibrated against initial marker trial results at Ernest Henry mine, Australia. All the contents of this journal, except where otherwise noted, is licensed under a Creative Commons Attribution License. Each production area needs two to three active drawpoints.