Statistical assessment of geological risks on the example of BIF deposits

摘要

Geological risks express the probability of confirming quantity and quality of reserves during the further reserves exploitation. Most of Ukrainian BIF deposits are exploited so geological risks as a result affect the mining profitability. In domestic practice, statistical risk assessment is carried out in determining the complexity of the geological structure. Most of evaluation objects (BIF deposits within Kryvyi Rih region) belong to 2 or 3 group of complexity. Geological parameters in such groups are characterized by variations above 40%. The study object was one of BIF deposits within Kryvyi Rih region which is exploited for iron concentrate and pellets production. Statistical analysis of quality and quantity parameters was done for Fe common grade, Fe grade associated with magnetite, thickness of ore bodies, processing indicators (Fe grade in concentrate, Fe extracting level, output of iron concentrate and pellets). It was defined that largest values o f variation and associated risks are characteristic of Fe grade associated with magnetite and thickness of ore bodies with variation coefficient 0. 26 and more 0. 8 respectively. Processing indicators (especially Fe grade in concentrate, Fe extracting level) are relatively stable. The most sensitive indicator to changes in ore grade is output of iron concentrate and pellets.