Mammoth Water Extractor – Risk Matrix
Mammoth Water Extractor
FREQUENCY-LIKELIHOOD
| Frequency Level | Description | Frequency of Events |
|---|---|---|
| 5 | Almost certain (occurs often) Expected to happen | Occurs on very Blast |
| 4 | Likely (known to occur) May easily happen | Occurs Once a Week |
| 3 | Possible (known to occur occasionally) May Happen | Occurs Once a Month |
| 2 | Unlikely (has occurred somewhere) May happen sometimes | Occurs Once a Quarter |
| 1 | Rare (could happen but unlikely) | Occurs Once a Year |
SEVERITY-CONSEQUENCE
| Severity Level | Impact | Health & Safety | Blasting Result & Outcome | Loss/Damage |
|---|---|---|---|---|
| 5 | Catastrophic/Critical | - Multiple Injuries - Misfired blast - Work on dangerous ground |
- Frozen ground - Re blast & repair cost - Production interruption - Penalties |
>R 1.0 Mil |
| 4 | Severe/Major | - Single Fatality/Permanent disabilities - Uneven broken ground removal - Risky work environment |
- Poor fragmentation - High loading cost - Slow production - Secondary blasting |
R.0.8 – 1.0 Mil |
| 3 | Major/Moderate | - Reportable injury/noise induced hearing loss - Property damage |
- Flyrock - Property damage - Financial loss |
R 0.5- 0.8 Mil |
| 2 | Moderate/Minor | - Lost time injury/Health effect with reversible impairment | ||
| 1 | Minor/Low | - Medical treatment case/ Slight health effect with no impairment |
STEMMING WET HOLES
- Ensure that the stemming material is suited to the stemming length to achieve the required result
- Water in the stemming area will affect the effectiveness of a consolidated stemming
- Bottom charge all water-filled holes. This will result in water on top of the charge
- Remove the water and explosives gunk in the stemming length with a water extractor before stemming the hole. The hole will be dry and the stemming can affectively be consolidated.
- 10% aggregate is normally used when;
- holes are situated in a pool of water
- to ensure the optimum fragmentation in very hard rock
- a short stemming is needed i.e., hard rock in collar area that may create slabbing.
- no flyrock is allowed in restricted areas
Drill chippings (not fine sand) can be used effectively in dry holes as indicated below
GENERAL STEMMING CHART ‐ FLYROCK EFFECT
| Hole Diameter | x Burden | Dry Hole Graded Aggregate | Graded Aggregate in Water | Dry Hole Drill Chippings | Drill Chippings in Water | Result ‐ Flyrock Effect |
|---|---|---|---|---|---|---|
| 10 x Dia | 0.4 x B | Moderate | High | High | Excessive | |
| 15 x Dia | 0.6 x B | Little | Moderate | Moderate | High | |
| 20 x Dia | 0.8 x B | Little or none | Little | Little | High | |
| 25 x Dia | 1.0 x B | None | Little/none | Little/none | Moderate | |
| 30 x Dia | 1.2 x B | None | None | None | Little | |
| 35 x Dia | 1.5 x B | None | None | None | None |