Both open pit and underground mine periodically take stock of how much mining has been done over a period, typically a month. Some operations may opt to carry out this process weekly or fortnightly. This of course is a matter of preference and a function of several factors one of which is the presence of the staff that can carry it out i.e. the mine surveyors. So, what exactly is being done during the End of Month process? Primarily the EOM effectively measures the outputs of the mining process by creating a “snapshot” of the operation at a point in time. Usually this consists of determining the meters developed, the volumes excavated, the volumes of stockpiles at their respective locations etc. The differences between two successive snapshots forms the basis of the calculations. This information has varying uses and applications. A few are detailed below:
Measure of efficiency
Efficiency is a measure of process outputs compared against the inputs used to gain said outputs. In mining, it is imperative to have a firm grasp of progress made in comparison to the inputs into the operation.
The mining process has a wide range of inputs; Equipment, labour, fuel, tyres, electricity etc and all of these cost money and in order to calculate the cost per ton or metre, the number tons or the metres mined need to be calculated. This input is drawn from the EOM process.
For one reason or another mining companies tend to use contractors to carry out their mining operation the most common reason being a cost related one as you only pay for what you mine. Most contracts for mine development are based on the metres mined or cubic metres of ground moved. Being able to establish these numbers accurately and consistently is very important to both parties in these arrangements.
The EOM process is used to establish how much money will be paid to the contractors for the works done for the month.
Progress of mining
The EOM process keeps track of how the actual mine development compares with what had been intended at the point of design. This is used in the calculation of how profitable an operation is when compared against the economic models. Faster mining is generally more economic than slow mining due to the presence of massive fixed costs.
Some countries required a submission of the state of the mines on a periodic basic. The snapshots of the mines combined with various other datasets provide this information adequately. The EOM process takes care of these requirements by showing the positions of the mined excavations, the volumes extracted and whether these conform to agreements made with the respective mining agencies with regards to safety and development rates.
The operational crews daily provide management with information regarding what has been achieved for the day. As an audit of these claim the EOM process provides accurate figures to verify these performance claims. These are primarily the reason behind the frequency of measurement. Accurate claims negate the need for frequent checks.