Abstract
The objective of this paper is to deliver a quantitative model that can be used to trade off trucking versus conveying as distinct ore handling mechanisms in underground mechanised low profile platinum mining applications in Southern Africa and potentially globally. Mining the platinum reefs in Southern Africa presents its biggest challenge in that the stoping width is typically no more than 2 metres in height. In the last 10 years, mining equipment OEMs developed a range of „Low Profile‟ equipment, specifically designed to fit within a two metre stoping width and in some cases, as low as 1.6metres in height. More recently, conveying systems have been introduced as primary and secondary haulage mechanisms. Some mines have adopted conveyors as a haulage mechanism whilst other kept with the more traditional trucking and hoisting options. The question therefore to be answered by this paper is; at which mining parameters do mines opt for trucking or conveying or combinations of these. A production/cost model was developed to this end. Three mines were selected based on their success in utilizing these haulage options. The Author conducted site visits to these mines to learn first hand about the decision making influences. Time studies conducted on these operations, combined with site data over the past 5 years forms the core information utilized to construct a production/cost model. The model considers most parameters such as operating cost (energy and labour), capital cost (capital investment cost for equipment, excavations, associated infrastructure, rebuilds and replacements on machine life intervals) and maintenance cost (maintenance labour, materials, infrastructure and overheads). A further parameter inclusion to the model is the future use of „sizers‟ in lateral drive conveyors to study the improvement provided should mines employing this technology not have to deal with oversize material on conveyors and subsequently having to leave ore bearing material in the underground environment. The study results proved based on mine parameters collected, that the combination of using trucks on the horizontal strike drives and tipping onto a decline conveyor to do the vertical haulage was the most cost effective and flexible method. Conveying of material from the stope face via a decline conveyor to surface came a close second, although many mine personnel expressed their concern regarding system flexibility and required effort in activities such as belt extensions. Further sensitivity analysis rated trucking as the most effective haulage method for mines that produce less than 114 000 tonnes/month. Another study proved that mines with and extended life of mine and high production volumes should be more effective using the full conveyor option. The outcome of the studies mentioned is reliant on specific mine parameters utilised, such as stoping width, tramming distances etc. Although the study methodology as far as possible attempted to normalise the effect of mine specific design parameters, the study results for each option was too close to each other to identify one outright winner. The Author therefore strongly suggests the use of the production/cost model developed, during feasibility stage to determine the best option for specific mine parameters.
Translated title of the contribution | Truck vs Conveyor Study in Low Profile Room and Pillar Applications |
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Original language | English |
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Publication status | Published - 2011 |