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Search Mining Rules of Thumb
| | | Mining Field: Backfill |
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Area: General |
| | • | The cost of backfilling will be near 20% of the total underground operating cost. Source: Bob Rappolt |
| | • | The capital cost of a paste fill plant installation is approximately twice the cost of a conventional hydraulic fill plant of the same capacity. Source: Barrett, Fuller, and Miller |
| | • | If a mine backfills all production stopes to avoid significant delays in ore production, the daily capacity of the backfill system should be should be at least 1.25 times the average daily mining rate (expressed in terms of volume). Source: Robert Currie |
| | • | The typical requirement for backfill is approximately 50% of the tonnage mined. It is theoretically about 60%, but all stopes are not completely filled and tertiary stopes may not be filled at all. Source: Ross Gowan |
| | • | It is common to measure the strength of cemented backfill as if it were concrete (i.e. 28 days), probably because this time coincides with the planned stope turn-around cycle. Here it should be noted that while concrete obtains over 80% of its long- term strength at 28 days, cemented fill might only obtain 50%. In other words, a structural fill may have almost twice the strength at 90 days as it had at 28 days. Source: Jack de la Vergne |
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Area: Hydraulic Fill |
| | • | Because the density of hydraulic fill when placed is only about half that of ore, unless half the tailings can be recovered to meet gradation requirements, a supplementary or substitute source of fill material is required. Source: E. G. Thomas |
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Area: Cemented Rock Fill |
| | • | A 6% binder will give almost the same CRF strength in 14 days that a 5% binder will give in 28 days. This rule is useful to know when a faster stope turn-around time becomes necessary. Source: Joel Rheault |
| | • | As the fly ash content of a CRF slurry is increased above 50%, the strength of the backfill drops rapidly and the curing time increases dramatically. A binder consisting of 35% fly ash and 65% cement is deemed to be the optimal mix. Source: Joel Rheault |
| | • | The size of water flush for a CRF slurry line should be 4,000 US gallons. Source: George Greer |
| | • | The optimum W/C ratio for a CRF slurry is 0.8:1, but in practice, the water content may have to be reduced when the rock is wet due to ice and snow content of quarried rock or ground water seepage into the fill raise. Source: Finland Tech |
| | • | The actual strength of CRF placed in a mine will be approximately 2/3 the laboratory value that is obtained from standard 6 inch diameter concrete test cylinders, but will be about 90% of the value obtained from 12 inch diameter cylinders. Source: Thiann Yu |
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Area: Paste Fill |
| | • | Only about 60% of mill tailings can be used for paste fill over the life of a mine because of the volume increase, which occurs as a result of breaking and comminuting the ore. Source: David Landriault |
| | • | Experience to date at the Golden Giant mine indicates that only 46% of the tailings produced can be used for paste fill. Source: Jim Paynter |
| | • | Very precise control of pulp density is required for gravity flow of paste fill. A small (1-2%) increase in pulp density can more than double pipeline pressures (and resistance to flow). Source: David Landriault |
| | • | 40% of paste fill distribution piping may be salvaged for re-use. Source: BM&S Corporation |
Mining Rules of Thumb have been gathered over 30 years of hard rock mining service provided by Stantec / Mining and predecessor firms.
The primary usage of Rules of Thumb should be in the development of conceptual
designs and feasibility studies or, when a quick decision is required in the solution of an operating
problem. Although an approximated answer, derived from a Rule of Thumb may solve an
immediate problem, Rules of Thumb are not a substitute for the application of sound engineering
and design methodologies. Although we firmly believe that the presented Rules of Thumb provide
great continuing value to our industry, McIntosh Engineering does not guarantee their validity, nor
do we (or the referenced individual sources) accept responsibility for application of the Rules of
Thumb by others. Where possible, direct quotes have been provided from individual references;
however, it is possible that referenced sources may not have directly stated the Rule of Thumb for
which they are assigned credit. Although we have endeavored to accurately quote all individual
references contained in the Rules of Thumb compilation, we apologize in advance for any misquotes
that may be attributed to individual sources. We will provide updates to the Rules of Thumb
compilation, as we become aware of corrections that may be necessary.
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