The use of injectable resins in mining operations has become increasingly versatile due to their ability to strengthen ground conditions and optimise processes in complex geological scenarios. A recent case study from Weber Mining examines the application of resin for stabilising a pillar on both sides of an ore block located near collapsed zones across multiple levels to facilitate long-hole drilling.
Initially, extracting the ore block without any fortification treatment was considered but ultimately dismissed due to safety concerns. While this approach would have allowed for complete ore extraction, it also posed a significant risk of losing the entire block and extending the collapse zone into the extraction area. The danger was further intensified by the presence of a significant collapse zone.
Weber Mining proposed an alternative: reinforcing a pillar between the ore block to be extracted and the collapsed area, stabilising both sides of the block to create a secure barrier for safe ore extraction.
Since there was no access to the upper gallery of the block, an upward drilling pattern was designed from the lower gallery to the block. This design enabled sectorised resin injection around the block’s perimeter. The drilling strategy included eight injection lines, spaced three meters apart, with three boreholes of varying depths, ranging from six to thirteen metres.
Given the variability of the ground – comprising different rock types and potential collapsed zones – this drilling template was crucial to ensuring the resin was applied effectively. During the injection phase, the resin migrated into the rock fractures until reaching a saturation point, at which injection was halted. A variability of up to 30% in resin consumption was observed on both sides of the drift due to fractures of different magnitudes.
Additionally, it was necessary to determine the most suitable type of resin for the varying ground conditions, as well as assess different levels of voids, injection distances, stabilisation surfaces, and the injection equipment used. Based on these parameters, a non-expanding resin was selected, offering a compressive strength of 35 MPa and a setting time of four minutes.
The resin’s rapid reaction time, along with the injection equipment used, ensured that the resin was applied solely for pillar reinforcement, avoiding unnecessary costs and delays. Ultimately, the entire drilling pattern was injected within just three days.
The strategic placement of injection points enhanced the precision of the ground fortification operation. Furthermore, the injection process started with the lowest boreholes to begin saturation from the pillar’s base, followed by an upward injection sequence. This approach allowed for sectorised injection, ensuring homogeneous coverage of the block.
Weber Mining says it is important to highlight that the resin’s adhesion capability is crucial for maintaining the integrity of the ore block. During long-hole drilling operations, the ground is subjected to high levels of stress, and the resin’s flexibility helps maintain cohesion throughout these phases, preventing any structural failure in the pillar’s stabilisation.
Starting from a highly complex scenario, where the most apparent solution would have been to leave a natural pillar, all relevant data was gathered to adapt the injection conditions and successfully stabilise two pillars with resin, optimising the long-hole drilling process.
Weber Mining has offices in France, Poland, Turkey, Australia, and Mexico, providing global support to mines with chemical solutions for ground reinforcement.
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