Managing Waste Rock Facilities at mines

Waste rock facilities (WRF) generally have a large footprint depending on the strip ratio the mine plan provides. Considerable planning is involved during the initial phase of the mine plan regarding the location of the WRF. As the mining operations are commenced the locations of the WRF change accordingly with the variations in the mine plan involving feedback and support from local communities and stakeholders. WRF management becomes challenging when the area available for placement is limited due to terrain topography, environmental and permitting constraints. Risks associated in the design of waste rock facilities constitute particle size of rock, chemistry associated with the rock for reactivity and stability of the overall facility.

WRF at the mines pose continuous challenges as most of the short haul WRF locations are valley fill and side hill fill. The contouring during construction becomes critical as the final WRF design have to blend with neighboring natural topography. The contouring is primarily achieved with operator experience and effective use of grade control technologies available in the new generation dozers. Effective scheduling during the construction of the WRF can be associated with cost-benefit analysis like fleet management, increase in tire life with respect to up-hill or down-hill haul, improvements in cycle time of the haul trucks by allocating multiple facility locations, efficiency in production tonnage by managing the shovel hang time by scheduling and sequencing the facility priorities.

WRF management becomes challenging when the area available for placement is limited and/or subject to permitting constraints. Risks associated in the design of waste rock facilities constitute type of rock size, chemistry associated with the rock for reactivity and stability of the overall facility. Considerable planning of WRFs is needed to allow flexibility in the strategic placement of materials on a day-to-day basis. WRF slope stability becomes critical under site specific conditions like steeply sloping terrain. Mitigation of potential failures of the WRF slopes at steep terrain can be achieved by designing buttresses and impact berms. Another mitigation of WRF stability is to control the placement of material; soft and fine grained material must be placed in the form of cells (plug facilities) and encapsulated with coarser rock.

The best management practices in WRF design can be achieved when geotechnical, geophysics and geochemical are considered from initial phase to closure phase of the WRF. 3I’s to sustainability and consistency in WRF operations can be: Improve – design with safety, technology usage for grade controls and slope contours. Involve – ideas and feedbacks from stakeholders should be considered and appropriate decision making needs to be initiated for implementation. Initiate – operations and engineering coordination for utilizing resources and technology for waste rock facility locations and monitoring during the life of mine.

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