What you will learn
- Why stockpiles are hard to measure, and why guesses are costly
- How loads in and draws out are recorded
- How surveys and measurements correct the book inventory
- What the plant, sales and finance teams each need from stockpile data
- Where stockpile tracking ends and grade control begins
What this project is
Stockpiles are the buffer between mining and processing, and between processing and sales. Ore stockpiles feed the plant when mining pauses; product stockpiles hold finished material for sale. Their contents change daily as loads are added and drawn. Without a system, the contents are guessed, and the plant plans on a guess, sales promises on a guess, and finance values inventory on a guess. A stockpile system records every load in and every draw out, with tonnes and grade, so the book inventory reflects what was actually moved.
Book inventory drifts from reality. Loads are missed, moisture changes weight, and material compacts or is lost. Periodic surveys, by drone, laser or traditional methods, measure the physical pile and correct the book figure. The system should record both: the book inventory from load records, and the surveyed inventory, with the difference investigated rather than silently overwritten. A stockpile whose book and surveyed figures disagree persistently has a measurement problem that needs fixing.
Core features
- Stockpile records with location, material type, tonnes and grade
- Load-in and draw-out recording, linked to fleet, grade and plant data where available
- Survey management: survey dates, methods, volumes and the correction applied
- Book versus surveyed reconciliation, with differences flagged and investigated
- Moisture and density handling, so wet and dry tonnes are not confused
- Reporting for plant feed planning, sales availability and inventory valuation
How it is built
- Map the stockpiles first: locations, materials, and how loads are currently recorded
- Build load-in and draw-out recording, linked to fleet or plant data where it exists
- Add survey management and reconciliation, then moisture and density handling
- Add reporting for plant, sales and finance, each with the cut of data they need
- Pilot on one stockpile for a month, comparing book inventory with a survey before wider use
Technology considerations
Measurement is the technical challenge. Load tonnes come from truck payloads, belt scales or loader counts, each with its own error. Grade comes from sampling, with its own error. The system should record the source and method for each figure, so a stockpile built from belt scale data is not treated as equally precise as one built from weighbridge data. Survey volumes need density to become tonnes, and density varies by material and compaction, so the density assumption should be recorded and reviewed, not buried.
Integration helps accuracy. If load data flows automatically from fleet or plant systems, missed loads become rare. If it is retyped, missed loads become routine. The system should also handle stockpile splits and merges: a pile divided for blending, or two piles combined, must keep their combined tonnes and weighted grade correct through the change.
For the first version, track one stockpile for a month: every load in and draw out, with tonnes and grade, then compare the book figure with a survey. Plant and finance teams judge the system on whether that comparison is close and explainable. A system that reconciles one stockpile, with moisture and density recorded, proves the method before it is applied to every pile on site.
Challenges to plan for
- Loads missed because they were recorded on paper and never entered
- Moisture changes that make wet tonnes and dry tonnes diverge
- Survey corrections that are applied without investigating why the book figure drifted
- Stockpiles split or merged without the grade calculation following the material
Who it is for, and its limits
This suits a mine operator, a processing plant or a bulk materials business holding significant stockpiles. It fits operations where stockpile contents drive plant feed or sales commitments. It does not fit a small operation with one pile and occasional use, and it is not a survey system: it records and reconciles stockpile data, while surveys are done by surveyors.
A stockpile system does not measure the pile. It organises the measurements and movements so the pile's contents are known, not guessed. Costs vary with stockpile count and data sources, so confirm with a quote after the stockpiles are mapped.
Frequently asked questions
What is book inventory?
The inventory calculated from recorded loads in and draws out. It is updated daily from movement records, and corrected periodically by surveys that measure the physical pile.
Why do book and surveyed figures differ?
Because of missed loads, moisture changes, compaction and measurement error. Small differences are normal; persistent or growing differences mean a measurement or recording problem needs fixing.
How is grade tracked in a stockpile?
As a weighted average of the grades of loads added, adjusted when material is drawn. Drawing from a stockpile should follow a method, such as first-in-first-out, so the grade of drawn material can be estimated.
Does moisture matter?
Yes. Wet tonnes weigh more than dry tonnes for the same material. The system records moisture where it is measured, so wet and dry figures are not confused in planning or valuation.
Can sales use stockpile data?
Yes, for availability: what product, how much, and of what grade is ready for sale. Sales should still confirm availability before committing, because a stockpile can change between the report and the sale.