Benchmarking narrow vein dilution provides realistic dilution estimates. In narrow vein mining, it is often not possible to limit stope width to the vein width when utilising blasting for rock breakage and this dilution results in lost productivity. PRODFINDERTM probabilistic benchmarking was used to estimate benchmark stoping widths and benchmark dilution for three commonly used narrow vein longhole blast patterns.
Average stoping widths for inline, staggered and dice-5 blast patterns have been estimated at 1.3, 1.5 and 1.7 m respectively. Average stoping width can be used to assess planned and unplanned dilution. Additionally, a concept termed the benchmark stability stoping width has been defined and quantified for the three blasting patterns. Stability stoping widths for inline, staggered and dice-5 have been estimated at 1.6, 2.0 and 2.1 m respectively. Narrow vein stopes within these limits can be regarded as stable, and within benchmark levels for dilution.