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LKAB MASTER THESIS

The orebody is first divided into cells. Historical data on drawpoint abandonment and other performance-related information can provide a baseline for assessing loading issues. Other methods discussed would benefit significantly from either model improvement or improvement in drawpoint monitoring technologies. In Kiirunavaara mine, boulders are broken by a stationary, remotely controlled rock breaker located at the grizzly at the top of the orepass. Sensitivity to mine design and ore geometry: Loading from the muckpile should be stopped during the sampling period in order to ensure a representative sample. 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.

Sublevel caving at Granduc. At this point, only the two first criteria are displayed in the LHD cabin for operators. A dynamic draw control strategy should be sensitive to the mine design and ore geometry. As production advances, the flat front pattern changes to a V-shape. The draw control strategies in Table III are assessed the based on 10 factors. Guidelines for designing a new draw control strategy. Low hang-ups caused by big boulders are sometimes drilled and blasted by a special crew.

The assessment shows that traditional draw control strategy, dilution entry method, and non-dilution methods are not recommended for draw control purposes. An analysis of the draw control and loading operations at thewis Malmberget and Kiirunavaara mines is summarized using information collected through interviews, internal documents, meetings, and manuals.

lkab master thesis

Cut-off and shut-off grades should be included in the draw control strategy as well, while grade control should include marginal operating costs and metal prices to provide a more accurately calculation of the average ore grade and shut-off grade.

The method is an improvement on the dilution entry method and incorporates the recovery curves from the primary, secondary, thesos tertiary recoveries, i.

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Mining constraints are a set of defined constraints to ensure a safe and efficient operation. Like Malmberget, Kiirunavaara is constrained by seismicity and blasting.

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thesjs The performance of the drawpoints above a blasted ring has an influence on the ore grade that will be extracted from the drawpoint. The recovery model is calibrated by correlating the diluted average grade from past production data with the actual average grade measured at the mill.

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Drawpoints near the hangingwalls have an open cavern at later stages of the draw; thesiw hangingwalls have not yet caved or have just started llab cave, creating an open cavern above the drawpoint. The bucket weight reading is used to estimate the percentages of ore and waste in the bucket visualized in Figure 1 Gustafson et al. The draw control strategy at Telfer was optimized by maximizing the undiscounted profit of each draw column Jamieson, In future studies, the model will be calibrated against complete marker trial results, thus providing a better prediction of mineral production and material flow Power and Campbell, Non-dilution draw method Zhigui and Xingguo state that cut-off grades are the primary problem lkag the current draw control strategies and propose a ‘non-dilution draw’ method.

lkab master thesis

In general, a straight cave front is maintained; this transitions into a V-shaped sequence with the vertex pointing away from the entry point into the orebody.

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This data can be used to calculate the average grade of a mined ring and observe the variation in ore flow throughout the loading process. From a critical review of the published literature, a qualitative assessment can be performed to score the different draw control strategies and comment on their use in mines Table IV.

A model for gravity flow of mastfr rock in block caving mines. A cell is connected to other cells based on a weighted system used for neighbour calculations. Modeling granular flow in caving mines: A study of isolated draw zones in block caving mines by means of a large 3D physical model.

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Sublevel caving-today’s dependable low-cost ‘ore factory’. The initial inflow of loab 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.

The International Caving Study. 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.

Zhigui and Xingguo state that cut-off grades are the thsis problem with the current draw control strategies and propose a ‘non-dilution draw’ method. The loading process and draw control near the hangingwall are guided by safety concerns. Therefore the remaining parameters – final extraction ratio, ore grades, and stoppage issues are vital to an analysis of drawpoint performance in an operating mine. Sensitivity to mine design and ore geometry: The issue of when to stop loading from the drawpoint and blast the next ring is at the centre of draw control strategies Sarin, Services on Demand Article.

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Similarly, Bull and Page define an effective draw control strategy as one that maximizes ore recovery while minimizing dilution and delaying dilution entry thewis the drawpoint by deploying ‘corrective methods’.

It is, however, very expensive, and is more time-consuming than visual estimation. The monitoring of the ore grade at the drawpoint is termed ‘grade control’ Booth et al. How to cite this article. The weight is directly proportional to the distance from the main cell to the sampling point of the neighbouring cell Salinas, However, if partial development is under way, mining cannot be done in those production drifts.

lkab master thesis