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ANGLOCOAL LANDAU COLLIERY. COMBATING SPONTANEOUS COMBUSTION. VERENA. LOCALITY PLAN. KROMDRAAI OPENCAST. WITBANK. WITBANK. MIDDELBURG. N4. PRETORIA. N4. NAVIGATION PLANT. RLT. CLEWER. GREENSIDE. KLEINKOPJE. BETHAL. JOHANNESBURG. N12. N. HISTORY OF KROMDRAAI.
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ANGLOCOAL LANDAU COLLIERY COMBATING SPONTANEOUS COMBUSTION
VERENA LOCALITY PLAN KROMDRAAI OPENCAST WITBANK WITBANK MIDDELBURG N4 PRETORIA N4 NAVIGATION PLANT RLT CLEWER GREENSIDE KLEINKOPJE BETHAL JOHANNESBURG N12 N
HISTORY OF KROMDRAAI • Known as Coronation Colliery, • Underground mining commenced in 1926, • Underground mining finished in 1966, • Total of 35 million tons mined, • Mined by “handgot” methods.
STRATIGRAPHIC COLUMN TOPSOIL AND SUBSOIL 2,0 WEATHERED SANDSTONE 6,0 CLAY 9,0 WEATHEREDSHALE 10,5 SHALE 12,5 SANDSTONE AND SILTSTONE 17,5-26 2,2 19,7 NO.2 SEAM 2,7 22,4 SANDSTONE PARTING 23,0 2,7 NO. 1 SEAM 25,7 SHALE 26,0 TILLITE
FACTORS ESSENTIAL FOR SPONTANEOUS COMBUSTION • HEAT SOURCE • CARBONACEOUS MATERIAL • AIR
LANDAU’S MAIN INITIATIVES WERE TO REDUCE THE AMOUNT OF AIR ENTERING THE WORKINGS
METHODS TO REDUCE AIRFLOW • SEALING OF GEOLOGICAL BOREHOLES, DISUSED SHAFTS & SINKHOLES • BUFFER BLASTING • BLAST DESIGN-HOLES IN PILLARS, EXTRA CHARGE IN THICKER PARTINGS • SEALING FIRES AND UN-COLLAPSED PILLARS, BY PUSHING SOFTS OVER THE HIGHWALL
DRILLING AND BLASTING TOP HAT SOFT OVERBURDEN HARD OVERBURDEN ANFO GAS BAG GAS BAG 2 SEAM PARTING U/G WORKINS 1 SEAM
PILLAR HOLES TO FLOOR INTERSECTION HOLES TO TOPOF COAL POSITIONING OF BLAST HOLES
BLASTING PROCEDURES • RISK ASSESSMENT ON HOT HOLE CHARGING DONE IN CONJUNCTION WITH AEL • TEMPERATURE OF EVERY SHOTHOLE IS MEASURED - MAX 60 DEG. • BENCHMASTERS REPLACED CORDTEX DOWN THE HOLE • EVERY HOLE PLUGGED WIT TOPHAT AFTER DRILLING
BURNING PIT CONDITIONS SHOWING THE WORST SCENARIO
ADVANTAGES AT KROMDRAAI • HIGH SOFTS TO HARDS RATIO - GOOD SEAL AFTER BLASTING • THE SIZE OF THE PIT (2.5KM) ENSURES A DRAGLINE CYCLE OF APPROXIMATELY 3 MONTHS - HENCE THE BUFFER DOES NOT STAND FOR EXTENDED PERIODS
FURTHER CONSIDERATIONS • DE-WATERING OF U/G WATER BODIES IS SCHEDULED SUCH THAT WATER REMAINS IN THE WORKINGS AS CLOSE AS POSSIBLE, TO THE MINING WINDOW
CURRENT PIT CONDITIONS • BLAST HOLES NOT WARM LESS THAN 4% OVER 60 deg. IN THE LAST YEAR • HOT HOLES ARE SEALED AND LEFT UNCHARGED, MARKED ON PLAN, REDRILLED 1m AWAY FROM PREVIOUS POSITION AND CHARGED WITH NEXT BUFFER LINE. (we have a second chance with buffer blasting)
HOTHOLE CONTROLE • CLAD THE SAME DAY FOR BEST RESULTS • DO NOT OPEN FIRES IN OPEN PIT MINING