Month-end in contract mining: last load to invoice
Month-end in contract mining turns loads, hours and delays into a signed invoice: survey against truck counts, standing time, sign-off and a checklist.
What it costs to move a tonne or a bank cubic metre, and how contractors price, record and bill that work. This section covers cost per tonne, BCM and rates, standing time, plant hire, month-end and the contract terms that decide what gets paid.
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Economics Guide
Cost per tonne in contract mining: what goes into the number
Cost per tonne is the hourly cost of a fleet divided by the tonnes it moves in that hour. What goes into the hourly cost, with a worked example in rand.
- BCM (bank cubic metre)A bank cubic metre (BCM) is one cubic metre of rock or soil as it lies in the ground, before it is dug.
- Load factorIn earthmoving, the load factor is the number you multiply a loose volume by to get the equivalent bank volume, and it equals 100% divided by (100% plus the material's swell percentage).
- Standing timeStanding time is time when a contractor's machine, usually with its operator, is on site, available and ready to work, but cannot work for a reason outside the contractor's control, such as a client instruction, a blast or a loader out of digging.
- Strip ratioStrip ratio is the amount of waste rock or soil that must be removed for each unit of ore or coal mined, expressed by volume, by mass, or in South African opencast coal as bank cubic metres of waste per tonne of coal.
- Swell factorSwell factor is the percentage by which rock or soil increases in volume when it is dug out of its natural bank state, because the broken pieces no longer fit together and leave air gaps between them.
