A study of the characteristics and behaviour of composite backfill material.

摘要

The history of mine backfill shows that in the past, considerable improvements in backfill-reliant mining technology were made when new fill systems were introduced. The present trend in mine backfill technology is towards the use of high-density fill systems. Tight filling and void reduction have also become essential requirements in engineering design of mines to ensure global stability. High-density fills have a low moisture content and are more competent products requiring less binder and time for stabilization, compared to conventional hydraulic backfill. Cemented rockfill and tailings/sand paste fills are two familiar high-density backfill systems in current use. In future there could be a high demand for low porosity high-density fills, as mines go deeper and ground stresses increase.; This study was an original attempt to investigate the characteristics and property of high-density composite fill systems. Composite fills are made up of derivatives of waste rock, tailings, sand and metallurgical by-products. Composite fills represent the future direction of backfill technology. As mines go deeper, the ore could be processed underground and the waste rock and tailings combined together to form a low-porosity competent fill product. The application of composite fill systems will also increase the material available for backfilling, provide more flexibility in backfill mix design and produce competent fill systems for ground support. It will also benefit the underground mine environment through effective utilization of mine wastes.; The fundamental basis of the work required the study and understanding of the characteristics and properties of cemented rockfill and paste backfill. The effects of sand addition to fine tailings as a means of reducing porosity and improving the mechanical properties of the fill product were also investigated. Additionally, a new concept of backfill, namely, Composite-Aggregate Paste (CAP) that consists of a mixture of fine tailings and graded coarse aggregates was introduced and the material properties were investigated.