Abstract
Paste backfill has become the industry standard for sustainable mine fill; minimizing surface tailings storage requirements, while maximizing resource recovery underground through the effective placement of good quality backfill.
To realize all the benefits of paste backfill, a ‘good’ product must be produced, meeting all the specified uncured and cured material properties, including ingredient quantities, rheology, early strength, and final strength. The consequences of a ‘bad’ product can be catastrophic in terms of safety, environment, and economics over the life of the mine.
The immediately short-term consequences of ‘bad paste’ include premature wear of distribution infrastructure, ruptures and blockages, re-entry delays, and bulkhead failure leading to the severe risk of inrush. While the often, less focused on, long-term consequences include full re-designs of stoping regions, paste failures and dilution, inefficient tele-remote mucking, and sterilization of ore. These consequences all have significant effects on the mining cycle, requiring labour and equipment hours to rectify and manage.
With a growing number of operations implementing paste backfill globally; surface plant and underground strategies, technologies and systems are continually being developed to aid in the production of a ‘good’ paste product. These include advanced plant control systems, live material and slurry property measurements, live remote pipeline pressure monitoring, live remote barricade monitoring, in-situ paste pressure monitoring, and direct/indirect in-field QAQC instruments. While the focus on qualified and trained backfill personnel to implement and operate these strategies, technologies and systems cannot be overlooked as being fundamental to the paste systems success. As often the root cause of ‘bad’ paste is not process or mechanical deficiencies, but rather the inability of the personnel to identify and rectify poor paste quality.
This presentation discusses ‘what is bad paste’, the immediate and long-term downstream effects of ‘bad’ paste fill and the technologies, strategies, and systems available along with personnel requirements to ensure quality production and placement, a safe environment underground and sustainable workplace. Two theoretical case studies have been developed to show the direct and downstream effects of ‘bad paste’ when placed into an underground void.