Abstract
The article aims at determining possible annual production considering mining and technical capabilities of the underground mine. Deepening of mining operations at Kryvyi Rih iron ore basin reduces considerably annual production of the useful mineral which results in increased mining costs. To maintain annual production, it is reasonable to build the second stage of opening the depth of which depends on production volumes. When determining the optimal depth of the first stage opening, it is necessary to apply a complex research method including the graphoanalytical one for determining the underground mine’s annual production and the industrial one for adjusting the methods considering technical conditions of the enterprise. It has been determined that annual production is influenced not only by mining and geological but also by mining and technical conditions. It has been proved that annual production of an underground mine decreases in direct proportion to the increased depth of mining. The speed of skips in the shaft is greatly impacted by the length of the main opening and its operating life. With the increase of the shaft operating life the skip speed decreases from 12 to 6 – 8 m/s. When designing the flowchart of further opening of underlying levels, it is necessary to consider both mining capabilities and technical conditions of the shaft and headgear, mining depth and the main opening operating life as well as the strategy of the mining enterprise. Consideration of the above mentioned factors enables maintaining the required annual production when mining iron ores at great depths. Under conditions of Kryvyi Rih iron ore basin, it has been determined reasonable to apply the main vertical shaft flowchart when mining reserves to the depth of 1650 m.
Highlights
Kryvyi Rih iron ore basin accounts for 10 bn t of ferruginous quartzite mined by open-pit and underground methods
The research conducted enables determining the fact that annual production of the underground mine impacts significantly the choice of an opening flowchart when mining reserves at great deaths
Combination of underground mine fields will considerably facilitate growth of economic indicators at the expense of increased annual production and distribution of the mined ore mass according to the useful component content
Summary
Kryvyi Rih iron ore basin accounts for 10 bn t of ferruginous quartzite mined by open-pit and underground methods. 1.1 bn t is made by rich ores with the useful mineral component of over 60% which is mined by the underground method. Underground mining of iron ores has deteriorated mining-geological and miningtechnical conditions resulting in 2 – 3-fold decrease of annual production and 1.5 – 2.5-fold increase of mining costs. Iron ore is mined at the depth of over 1300 m by traditional mining systems: bulk caving and open stoping. Ore drawing is performed by obsolete equipment (slusher or vibrofeeder), ore is transported in cars to the shaft and by 50t-skips to the surface [4 – 6]
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