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GROUND CONTROL. BASIC GEOLOGY, MINING METHODS AND GROUND CONTROL HAZARDS UNDERGROUND. BASIC GEOLOGY. THE STUDY OF THE EARTH IS CALLED GEOLOGY THE SOLAR SYSTEM INCLUDING EARTH WAS FORMED WITH GREAT FORCE AND HEAT INTERACTING WITH GRAVITY
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GROUND CONTROL BASIC GEOLOGY, MINING METHODS AND GROUND CONTROL HAZARDS UNDERGROUND
BASIC GEOLOGY • THE STUDY OF THE EARTH IS CALLED GEOLOGY • THE SOLAR SYSTEM INCLUDING EARTH WAS FORMED WITH GREAT FORCE AND HEAT INTERACTING WITH GRAVITY • THE EARTH COOLED WHICH RESULTED IN BUCKLING AND CRACKLING CAUSING PLACES OF ELEVATION AND DEPRESSION.
BASIC GEOLOGY • STRONG WINDS, WATER VAPOR AND ACIDS WEATHER ROCKS AND MINERALS • WEATHERING OF BEDROCK PRODUCES FINE PARTICLES FORMING SOIL OVER ROCK • FORCES OF EROSION CARRY AWAY SOIL CREATING DEPOSITS OF SEDIMENTS • PRESENT DAY ROCKS AND MINERIALS FORMED
BASIC DEFINITIONS • Mineral - a naturally occurring inorganic compound with fairly definite physical properties and chemical composition. • Rock - extensive mineral bodies, composed of one or more minerals in varying proportions, which constitute an important part of the earth’s crust. • Ore - are minerals from which one or more metals may be extracted at a profit.
TYPES OF ROCKS • IGNEOUS-SOLIDIFIED FROM MOLTEN MATERIAL AND INCLUDE GRANITE, FELSITE, DOLERITE AND BASALT • SEDIMENTARY-DEPOSITED AS A RESULT OF EROISION AND INCLUDE SAND, GRAVEL, SILT & CLAY AND LIME DEPOSITS • METAMORPHIC- IGNEOUS & SEDIMENTARY ROCK WHICH CHANGED FORM BY HEAT & PRESSURE AND INCLUDE SLATE, ANTHRACITE COAL, SANDSTONE, LIMESTONE, QUARTZITE AND MARBLE.
TYPES OF MINERAL DEPOSITS • MASSIVE--CONSIDERABLE LATERAL AND VERTICAL EXTENT WITH UNIFORMLY DISTRIBUTED ORE SUCH AS DOME SALT AND LEAD-ZINC DEPOSITS • BEDDED OR STRATA-BOUND--PARALLELS STRATIFICATION OF MOST OFTEN SEDIMENTALY ROCK, LATERALLY EXTENSIVE AND LIMITED THICKNESS SUCH AS COAL, POTASH, COPPER AND URANIUM DEPOSITS.
NARROW VEIN-- A TYPICALLY LONG, NARROW ZONE OR BELT OF ORE OFTEN DIPPING STEEPLY AND USUALLY LYING IN BOUNDARIES SEPARATING IT FROM NEIGHBORING ROCK SUCH AS NARROR VEINS OF GOLD OR METALLIC MINERALS • WIDE VEIN-- AS DEFINED ABOVE EXCEPT THAT THE VEIN THICKNESS IS GREATER THAN 10 FEET. • LENTICULAR OR POCKET--ISOLATED ORE BODY OR AN ENRICHMENT OF LIMITED VERTICAL OR HORIZONTAL EXTEND IN A MASSIVE, BEDDED OR VEINDEPOSIT SUCH AS LEAD, ZINC OR IRON
PORPHYRY--DISSEMINATED COPPER MINERALS IN A FINE GRAINED IGNEOUS ROCK MATRIX SUCH AS LARGE COPPER DEPOSITS • PLACER-FORMED BY SEDIMENTARY PROCESSES AT THE SURFACE OR NEAR-SURFACE CONTAINING MINERAL PARTICLES SUCH AS GOLD AND PLATINUM IN SAND OR GRAVEL
GEOLOGY AND GROUND CONTROL • Geology can be variable and geological conditions cannot usually be changed. • Mine planning must take into account as much detail as possible about the geological conditions that will be encountered by the mining operation. • Ground support method will be dictated by the geological conditions that will be encountered in the mining operation.
UNDERGROUND MINING METHODS • ROOM AND PILLAR • LONGWALL • CUT AND FILL • STOPES • BLOCK CAVING • SQUARE SET
CAUSES OF UNDERGROUND GROUND CONTROL PROBLEMS • BLASTING PRACTICES • FAILURE TO SCALE LOOSE GROUND • WATER EFFECTS • GEOLOGICAL--FAULTS, SEAMS,OR POOR GROUND
FAILURES AND GEOLOGY • Underground • Roof falls • Span • Discontinuities • Rib rolls (falls)
PREVENTATIVE MEASURES • Geology • Qualitative description of conditions • Rock types both composition & extent • Discontinuities • Numerical rating of rock - a consistent method to evaluate rock and put the results into a format that can be used for subsequent comparison and engineering design.
PREVENTATIVE MEASURES CONTINUED: • Mine design • Strength of rock (compressive, tensile, shear) • Shape of openings • Size of openings and pillars • Number of openings and spatial relation • Vertical and/or Horizontal stress
PREVENTATIVE MEASURES CONTINUED: • Recognizing hazards • Use your eyes and ears to evaluate conditions • Cracks, joints or loose pieces • Weight on pillars, roof, and supports • Be alert when rock composition changes • Floor heave • Wet conditions
PREVENTATIVE MEASURES CONTINUED: • Scaling • Factors to consider • Scaling Vs. Bolting • Two methods of scaling • Manual (hand) - equipment, location, technique • Mechanical (remote) - safer, sensitivity
VISUAL INSPECTIONS-ROOF & RIB • STRESS CRACKS IN ROOF, FLOOR & RIB • KETTLEBOTTOMS, CLAY VEINS, OR ABNORMAL ROCK FORMATIONS • A FORMERLY DRY PLACE THAT BECOMES WET • SMALL CHIPS OR BARK AROUND TIMBERS • MOISTURE OR CRACKS THAT APPEAR IN THE ROOF AFTER BEING SUPPORTED
VISUAL INSPECTIONS-SUPPORTS • BENT CROSSBARS, TIMBERS, OR POSTS OR HEAVY PRESSURE • ROCK BOLT BEARING PLATES THAT SHOW SIGNS OF STRESS • CAP PIECES SQUEEZED DOWN AND OVER POSTS • TIMBERS DECAYED THROUGH TIME.
PROPER ROOF TESTING • VISUAL EXAMINATION • SOUND AND VIBRATION METHOD • ALWAYS STAND UNDER SUPPORTED ROOF WHEN TESTING • ALWAYS START FROM SUPPORTED ROOF AND EXAMINE TOWARD THE FACE • NEVER TURN YOUR BACK TO THE FACE OR RIB WHEN TESTING
PROPER ROOF TESTING • START TAPPING THE ROOF LIGHTLY AT FIRST WITH A SOUNDING ROD; THEN INCREASE YOUR STROKE TO HEAR THE SOUND OF THE ROOF AND/OR FEEL THE VIBRATION • ALWAYS USE AN APPROVED TESTING TOOL • ALWAYS WEAR GOGGLES TO PROTECT YOUR EYES
57.3430 Activity Between Machinery or Equipment and the Highwall or Bank. • Persons shall not work or travel between machinery or equipment and the highwall or bank where the machinery or equipment may hinder escape from falls or slides of the highwall or bank. Travel is permitted when necessary for persons to dismount.
57.3430 PPM • This standard is applicable to surface mines and surface areas of underground mines. It addresses the hazards which exist when persons work or travel near a highwall or bank and their escape from a fall or slide of material could be hindered by the machinery and equipment in their escape path.
57.3430 PPM Cont. • If escape could be hindered, no work or travel is permitted. If, however, the machinery or equipment poses no hindrance, the standard is not applicable. Consideration must be given to: the height of the wall or bank; the distance between the equipment and wall or bank; the size and positioning of the equipment; the location of the worker in relation to the escape route; and any surrounding noise levels or distractions which could prevent the detection of falling ground.
57.3430 PPM Cont. • Where machinery or equipment becomes disabled near a highwall or bank, the equipment operator can often safely exit on the side away from the hazard. If this is not possible, exit on the wall side is permitted. Remounting on the wall side may also become necessary in order to reposition or move the equipment to a safe location for repairs.-
57.3430 PPM Cont. • -When the equipment is not removed for repair, it must be repositioned at the site so that workers will not be exposed to fall of ground hazards from which their escape is hindered.