Laserfiche WebLink
3.4 Resue Mining Method <br /> Based on the orientation and width of the mineralization, review of historic mining, and <br /> available geotechnical information, a resue mining method is used to mine ore where waste <br /> rock serves as backfill as the stope is advanced in an overhead manner. This method is highly <br /> selective and allows for mining narrow widths down to 0.5 ft. <br /> Resue mining involves identifying a stope block having minimum approximate dimensions of <br /> approximately 500 to 1,000 ft along strike and up to 300 ft in height. Stope block widths <br /> vary according to mineralization. Typically, an off-ore access drift is developed on the <br /> footwall along the length of the stope. Two-compartment raises known as cribbed manways, <br /> are developed on each end of the stope from the level below providing access to any level of <br /> the stope. In the center of the stope a four-compartment service raise with a manway, two ore <br /> passes, and equipment slide is constructed as the primary access. Each raise provides utility <br /> access into the stope so that miners can pull water or air from either side of the stope or from <br /> the middle service raise. <br /> The bottom portion of the stope, approximately 25 ft in height, is left in a pillar (sill pillar), <br /> which is partially recoverable from the stope below. A 3.5 ft wide scram drift is developed <br /> along the length of the stope above the pillar. Finger raises with ore chutes at the access level <br /> connect the scram drift to the development access below and are used to remove ore material <br /> from the stopes. Once the scram and finger raises are established,upholes are drilled into the <br /> vein,both in ore and waste. Ore material is blasted first and then removed using slushers <br /> operating on a conveyor belt muck sheet to the finger raise for transportation to the mill. Prior <br /> to blasting the waste material, cribbed timbers are placed to raise the ore passes (similarly to <br /> the manway and service raises) to the next level. Waste material is then blasted and left in the <br /> stope as fill material for accessing the next level of the stope. Where necessary, additional <br /> waste can be drilled and blasted to fill the stope as mining progresses. <br /> 3.5 Explosives and Blasting <br /> Various types of explosives have been used at the Revenue Mine and depending on the location <br /> can consist of dynamite (stick power),ANFO (ammonium nitrate/fuel oil), or some combination <br /> of the two. Detonators are fuse primers,nonels, or electric blasting caps. All explosives will be <br /> stored underground at two locations— one in the Yellow Rose drift and another near the Blue <br /> Lagoon on the Monongahela, as shown on Map C-IA and Map U-2,respectively. All explosives <br /> will be stored and handled according to Mine Safety and Health Administration (MSHA) and the <br /> Agency for Tobacco, Firearms and Explosives (ATFE) regulations. <br /> Blasting is not expected to impact surface structures. Little to no vibrations would be felt at the <br /> surface from underground blasting due to the size of the blasts and the distance to the surface. <br /> OSMI calculated the Peak Particle Velocity (PPV) for a variety of blasting scenarios. The closest <br /> OSMI would mine to the surface would be 50 feet. The PPV at that distance would be 17-20 <br /> mm/s,which is the lower limit that a drywall structure could be damaged. There are no structures <br /> planned that would be located above the areas where blasting will be taking place. Typical <br /> blasting scenarios would be more than 200 feet from the surface,would be barely detectible, and <br /> Revenue Mine <br /> Amendment 02 D-8 <br /> Updated August 2022 <br />