A team of engineers at the Big Gossan underground mine have found a way to make paste fast enough to keep up with the mining of the high grade copper and gold in PTFI’s only stope mine.
In early 2020, Big Gossan Engineering calculation show 2021 production would suffer due to low paste supply. Based on 2019 data on the mill and the paste plant (BGMF-BGPP), mine planners realized that paste production, which averaged 1,500 cubic meters per day, was falling behind ore production forecasted for 2,200 cubic meters in 2021.
Located relatively close to the existing mill facilities, Big Gossan reserves total about 54 million metric tons with a copper grade 2.26% and gold at 0.99 grams per metric ton. Production averages 7,000 tons of ore per day.
Because of the deposit geometry, Big Gossan is mined using a blasthole sublevel stoping method, were blocks of ore are mined out and filled back in with a pasted consisting of mill tailings and cement.
“Stope compliance issue will affect Big Gossan Ore production due to the limited space to run the stope sequence plan,” said John Wilmot, Vice President-Concentrating.
Without improvement in paste production, the potential loss of ore in Big Gossan for 2021 was estimated at 377,000 tons, equivalent to about $46 million in metal.
“We have been working on the project with maintenance improvement in BGMF-BGPP with the primary driving force behind the project is to increase paste production and to eliminate that production risk at BG Mining,” he added.
Improve Machine Performance and Field Devices
In June 2020, a number of critical improvements were identified by the Project Implementor team.
“Pumping a slurry to underground brings challenges. A flushing line has been installed to prevent plugs in the pipe and detect leaks," said Eko Purnomo, Senior Manager Concentrating Operation.
The team used an online platform from Honeywell to record downtime at the mill, which allows Mill personnel to plan and manage paste production more effectively.
“The insights provided by Honeywell help to eliminate ‘guess work’. Armed with quality data, the maintenance team can tackle accuracy, structured and recordable downtime event with a much better understanding,” said Aris Raharjo, Senior Manager Concentrating Maintenance.
Access to this high quality, accurate data is enabling underground mine engineers to optimize the Big Gossan mine plan.
Predictive and Preventive Planned Maintenance
To avoid unplanned downtime and increase equipment reliability, the running hours interface and preventive maintenance for machine and field devices has been established in Systems Applications and Products (SAP) for BGMF and BGPP.
Monthly past production has significantly increased since the project was completed in December 2020. Big Gossan went from having empty stopes waiting for paste to fill in the first quarter of 2020 to the superior position of having paste available and waiting for stopes to be emptied.
“In the long term, the additional paste production will eliminate this is as a production risk and big concern for Big Gossan Engineering,” Wilmot said.
Predictive and Preventive Planned Maintenance
To avoid unplanned downtime and increase equipment reliability, the running hours interface and preventive maintenance for machine and field devices has been established in Systems Applications and Products (SAP) for BGMF and BGPP
“By simulating the 2021 production plan, we can exceed the 2,200 cubic meter requirement and supply up to 2,492 cubic meters.” Wilmot said.
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