Large Diameter DrillingPhotos: NUNA<strong>Nuna</strong> Drilling ServicesNUNA Drilling’s Bauer BG 36 drill rig systems are capable ofdrilling 1,200 mm (4') diameter holes to a depth of 350 m(1,150'). These diesel-powered electric/hydraulic units utilizeCaterpillar-powered crawler units with retractable masts. After aunit is walked to a large diameter drill (LDD) location, overburden toa maximum depth of 85 m (279') is augered using a Kelly systemwith a selection of excavation tools. A Bauer-supplied oscillator isused to set and recover double-walled casing to as much as 40m (131') depth. Beyond that depth, or in harder formations, thesystem is reconfigured to use reverse circulation drilling.In reverse circulation mode, 6 m (20') long sections of9-5/8" double-walled drill pipe are added to the drill string utilizinga manipulator which enables an operator to handle pipe whilesafely removed from the suspended load. Compressed air issupplied down the hole between the inner and outer pipe walls.Air valves which form part of the drill string allow <strong>high</strong>-pressureair to enter the inner pipe at a distance above the hole bottomand to escape to surface; the vacuum created lifts slurry from thehole bottom. Holes are drilled in flooded conditions utilizing drilling“muds” to stabilize open holes below the casing.A variety of drill bits are employed to suit conditionswhich range from soft soils to rock with <strong>high</strong> compressivestrengths. Drill data is electronically recorded for later analysis.Sampling for diamonds in kimberlite is accomplishedthrough the use of a desanding unit which separates drilling fluidsfrom the sample, washes the sample and recovers materialsgreater than a specified size. The samples are bagged andtransported to a designated area.Drilling operations are 24 hours per day, year-round.Successful Projects by NUNA & PartnersShore Gold Inc.Star Diamond Project, Prince Albert, Saskatchewan, CanadaBulk Sample 184 Holes (39,000 m) (128,000')Shore Gold Inc.’s Star Diamond Project lies in Fort à la Corne,Saskatchewan, hosting one of the most extensive kimberlite fieldsin the world. The kimberlite is overlain by as much as 120 m(394') of overburden consisting of sand, mudstone, bouldersand glacial till.NUNA Drilling was chosen to conduct a large diameterdrill program, with an initial target of 72 holes, to collect bulksamples from the extensive area. Holes were 1,200 mm indiameter (4') with depths ranging to over 300 m (984').Working with Bauer Maschinen GmbH, NUNA Drillingdeveloped new equipment and techniques to drill holes in 2 stages.The process used 2 sets of fully-equipped mobile BG 36 drill rigs,bentonite and polymer solutions and primary support equipment;all provided by NUNA Drilling. Holes were “Kelly drilled” through thefirst 85 m of overburden and then the rigs were switched to reversecirculation drilling and geologists were provided sampling intervals.Rigs were walked between holes and the skid-mounted supportequipment was repositioned with support equipment. Operationscontinued year-round on a 24 hour basis.NUNA Drillings’ work for Shore Gold extended onto theFALC Joint Venture ground where a series of similar holes weredrilled. Accumulated drill program covered 184 holes (39,000 m)(128,000').www.nunalogistics.com
Dependable Project DevelopmentCommitted to Northern DevelopmentContract MiningPhoto: NUNAWith a large heavy equipment fleet and comprehensive support facilities, NUNA deliversa complete turnkey package for site construction and contract mining.
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