The marker trials have provided important knowledge on flow behaviour and dilution behaviour and have been used for mine design and ore flow simulation in SLC mines. Ore recovery was calculated for different sublevels. Tonnage-based draw control strategy. Fragmentation is difficult to measure continuously, while drawpoint dimensions tend to remain constant. Chamber of Mining Engineers of Turkey, Ankara. Low hang-ups caused by big boulders are sometimes drilled and blasted by a special crew.
An assessment of dilution behaviour is required to decide which aspects of dilution, if any, should be included in the draw control. Draw control strategy at Kiirunavaara mine. A high hang-up is difficult to manipulate using the LHD bucket, but a low hang-up can often be resolved. Figure 7 shows an example of a mining sequence at Kiirunavaara. Draw control strategies based on ore flow prediction models suffer from a lack of complete knowledge of the chaotic and random nature of material flow. Calibration of a mixing model for sublevel caving.
However, there is an opportunity to create a new draw control strategy using the above guidelines. The ability to change grade values is essential in order to maintain a profitable operation, but the changed value should be reflected in the draw control strategy by adjusting either the extraction ratio targets or production capacity.
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The model uses a layer concept, whereby an IMZ is comprised of a number of disk-shaped layers, and its growth is based on incremental laws applied at layer levels Pierce, ; Sellden and Pierce, The current draw control strategies at Kiirunavaara and Malmberget mines are guided by a bucket-weight-based drawpoint monitoring system.
The method is an improvement on the dilution entry method and incorporates the recovery curves from the primary, secondary, and tertiary recoveries, i.
Mining constraints for draw control. The draw control factor is based on the variation in tonnage from working drawpoints. Loading issues Loading llkab the drawpoint is sometimes stopped early because of loading issues, such as hang-ups, brow failure, pillar failure, intrusions, poor fragmentation, or ring freezing.
Newcrest dilution model and SLC optimizer The Newcrest dilution model and SLC optimizer can be divided into a recovery model and a draw strategy optimization model Jamieson, Draw control strategy at Malmberget mine Malmberget mine consists of about 20 orebodies, 12 of which are currently being mined.
In general, the cave front converges towards masrer entrance crosscut.
Basic ore flow principles, results from experiments, and past thesi data can provide a framework to optimize draw control to a mine’s specific design and ore geometry requirements.
Systems can provide ore grade measurements continuously Quinteiro, Larsson, and Hustrulid, or periodically [e. The operator can change the visualized graph if he or she wants to see, for example, iron ore content, extraction ratio, waste rock content, bucket number, tonnage. The average mine grade and shut-off grade can thesiis depending on mine conditions and are revised periodically by mine management.
Guidelines for designing a new draw control strategy An optimized draw control strategy is vital to ensure improved ore recovery and reduced dilution.
However, both masterr a draw control strategy that considers the production requirements and mining constraints and regulates the loading process through a continuous drawpoint monitoring system. As mines generally have machines with different bucket sizes, the WOLIS system uses different X and Y values stored for the different machines.
The material can be loaded from the adjacent drift to theais to loosen and release low hang-ups, while a production ring can be blasted in the adjacent drift to release high hangups.
Low hang-ups caused by big boulders are sometimes drilled and blasted by a special crew. Some orebodies in Malmberget contain waste intrusions.
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Mining constraints for draw control The mining sequence at Malmberget varies for different orebodies and mining levels but is primarily guided by the development situation of the level below. The weight is directly proportional to the distance from the main cell to the sampling point of the neighbouring cell Salinas, Previous work cited in the literature and other results from physical models, marker trials, and field data analysis have identified seven factors of SLC which affect draw control; these are discussed in Table I.
Because of this, the loading procedure for these rings is different. In field tests performed in test areas at Jing Tie iron ore mine, China Zhigui and Xingguo,the method was used with a shut-off grade of An analysis of the draw control and loading operations at the Malmberget and Kiirunavaara mines is summarized using information collected through interviews, internal documents, meetings, and manuals. Draw control strategies The issue of when to stop loading from the drawpoint and blast the next ring is at the centre of draw control strategies Sarin, Cokayne concludes that this method is more accurate than visual estimation.
If the 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.
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Issues related to seismicity and orepass availability are taken into account during planning and scheduling. Nonetheless, boulders are frequently encountered in the orepass mxster in the lower output of the orepass. XRF, spectroscopy must be developed to monitor thesi grade for copper, gold, or other metals being mined using caving operations. In these situations, LHDs can load directly onto trucks but this reduces productivity. Similar arguments can be put forward about other methods.