Blockages at draw points in caving operations can cause delays and disruptions to production and plans. They create safety risks and the need for unscheduled work to remove such blockages.
Draw point blockages are usually caused by oversize material and th ability to quickly and reliably identify large rocks in draw points is critical to enabling fast, safe reactions to these events.
In 2019 a large block caving copper mine in Chile required a solution for this problem. Oversize was difficult to predict and identify.
An oversize event in a scheduled production location in a block cave mine can cause typically 10% loss of production for a given shift, depending upon the ability to relocate equipment and alternate location availability. A consistent, reliable way of evaluating the availability for production and safety in each drawpoint was required.
Cave draw points are required to have high availability for production. Long durations of measurement or complex measurement requiring placement of scale objects in a scene are not practical in a mining production environment. Draw points are safety risk areas and the main priority is to maintain consistent production rates at all scheduled locations.
The solution recommended to enable oversize identification for this mine was PETRA’s FRAGx system using data available from the vehicle mounted Maptek SR3 scanner already in use at the mine.
The use of a vehicle mounted scanner enabled safe and very fast data acquisition at appropriate intervals to ensure the material at each draw point was not being blocked by oversize. Capturing appropriate scan data for FRAGx takes only 6 minutes and does not require any personnel to leave the light vehicle the scanner is mounted on.
As soon as that data is captured, it can be processed using FRAGx to identify any large rock fragments in the material. Processing by FRAGx only requires another 5 minutes and a report and graphical view of the fragmentation distribution is available to production decision makers about the availability and safety of the draw point. Informed decisions about production at each planned location can be made and decisions about clearing any blocked draw points can be made with better information available.
This solution was identified as being the most suitable for this mine as it was a priority to not interfere with production operations while still providing decision support about oversize blockages at drawpoints. The need to have information quickly and accurately was critical to the success of the solution.
The mine was routinely using the vehicle mounted scanner for various survey pickups of stockpiles already, so the addition of drawpoint scanning was quite easy. A sample of data at recommended spatial density was provided to PETRA by the site surveyors and FRAGx machine learning models were trained to identify oversize material.
Point spacing of minimum 20mm was adequate to provide good definition of the shapes and sizes of material in the pile. These models were provided with FRAGx to allow the mine to then analyse each pickup within minutes.
The training and creation of the FRAGx models took about one week, and the solution was ready to be used after then. The total cost for the solution was less than $USD40,000 for the whole mine.
The outcomes from using FRAGx were that the mine production management team had timely reports on oversize occurrences at drawpoints and could quickly replan in advance equipment locations and allocations to best meet production targets.
Safety risks were reduced by not having boggers exposed to oversize material and blocked drawpoints could be scheduled for clearing faster. Production losses and delays were reduced as a result of this implementation. The longer term benefits were better compliance to plan, more proactive production scheduling and better safety performance with less equipment damage.