Secondary Breaka e Practice at the DOZ Block Cave Mine

摘要

Ore fragmentation at the DOZ block cave mine is highly variable,both asrna function of rock type and column height of draw.rnInitially,the mine was constructed and equipped with limited capabilityrnto handle drawpoint oversize material.Significant issues with drawpointrnavailability and achieving overall mine production targets resulted.A suiternof secondary sizing tools was added to the mine equipment fleet over arnone-year time frame.Although significant oversize continues to bernexperienced,use of the correct secondary breakage tool for each particularrnoversize or hang-up occurrence has resulted in increased drawpointrnavailability,production rate,draw compliance,and operator safety.rnCurrently,a range of secondary breakage techniques is being utilised tornsize material for delivery to the primary crusher.Run-of-mine materialrn(<1 m 3 )is directly mucked to ore passes fitted with grizzlys that havernone-metre square openings.Ore containing small boulders (>1 m 3 ,<2m 3 )rnis loader-trammed to ore passes fitted with rockbreakers.Medium-sizedrnboulders (>2 m 3 )accessible from the drawpoint are drilled with SandvikrnTamrock Commando drills.Boulders hung-up within the drawbell arerndrilled and charged with a Sandvik Tamrock Secondary Breakage Unit.rnCompacted,fine-grained muck is blasted utilising 55 mm cartridge powderrnconcussion bombs.rnThis paper will:rn1.provide a summary of predicted ore fragmentation,rn2.describe the utility of each secondary sizing piece in the minernequipment fleet,andrn3.describe the benefit of these sizing tools.