The investment necessary to start a mine is of the order of 10's to 100's of millions of dollars. In order for the investment to be profitable, the potential product in the ground must be present in adequate quantities and quality to justify a decision to invest. Mining and processing systems used to extract the products must then operate so as to produce revenue to offset the planned investment and to provide an acceptable profit. Clearly, all technological and financial decisions regarding planned production are built on an understanding of the mineral assets available.
Thus, the estimation of grade and location of material in the ground (in situ resources) must be known with an acceptable degree of confidence. This is especially true of certain large, low grade deposits for which grade is only slightly above minimum profitable levels, and for some precious metal deposits where only a small percentage of mineralized ground can be mined at a profit. Mining profits are strongly leveraged to product price and to realized grade of material mined. A small difference between planned (estimated) and realized production grade, or a small change in metal price, can have a large impact on mine profitability.
The three undertakings, ore estimation, mine planning and grade control, are complementary in an efficient mining operation and are natural progressions one to another. The integration of these three endeavors is important because the grade control system must balance with the ore reserve as well as with the final products of the operating plant, and both estimation and grade control are influenced by planned operational procedures. If this balance is not achieved then the original investment may be in jeopardy. Reappraisals of mineral inventories can be necessary many times both prior to and during the life of a mine.
Resource/reserve estimation procedures commonly are considered in two categories, empirical and geostatistical. This course is confined to the principal empirical methods of estimation.
The principal topics covered include:
- Essential Concepts, Geological Continuity, Value Continuity
- Dilution, Regionalized Variables, Accuracy and Precision, Block Estimation
- Ore/Waste Boundaries, Conditional Bias, Cross Validation, Systematic Approach
- Sectional Methods, Polygonal and Triangular Methods, Inverse Distance and Contouring
The course comprises 16 working sessions, 5 exercise sessions, numerous figures and supporting materials, and 4 interactive review sessions designed to confirm the learning objectives. Course duration is equivalent to approximately 18 hours of viewing content.