WASTE ROCK MANAGEMENT AT SANGATTA COAL MINE A CULTURAL CHANGE. By Peter Scott HLA- Envirosciences Pty Limited

Transcription

1 WASTE ROK MANAGEMENT AT SANGATTA OAL MINE A ULTURAL HANGE By Peter Scott HLA- Envirosciences Pty Limited

2 WASTE ROK MANAGEMENT AT SANGATTA OAL MINE - A ULTURAL HANGE AKNOWLEDGEMENTS Deddi Hndiko Mtthew Orr

3 AID DRAINAGE IS THE MOST SIGNIFIANT ENVIRONMENTAL MANAGEMENT IUE FOR THE MINING INDUSTRY IT IS AVOIDABLE

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5 AGREEMENT AREA MINE AREA

6 ULTURAL HALLENGE hnging the wy mine trditionlly opertes to solve very serious environmentl nd potentilly high cost prolem hnging the culture of Mine mngement t one the Worlds lrgest col mines Used science to cross culturl oundries Good news story

7 SETTING Sngtt ol mine formerly owned nd operted y PT Kltim Prim ol is locted in undulting costl uplnds of Est Klimntn degree north of the equtor The site hs n equtoril climte with high nnul rinfll of 2500mm The mine is one of the Worlds lrgest truck nd shovel opertions with lrge volumes of overurden mined nnully with high stripping rtio Pyrite is the principl sulfide in the wste rock

8 SETTING Potentilly cid forming wste rock (PAF) contining pyrite represents 20% of the overurden tht will e mined to extrct the col resource. The wy the mine PAF wste ws eing mixed with non-cid forming wste (NAF) which ment tht most of the dumps could potentilly generte cid dringe This hd to e chnged to control cid dringe

9 PRODUTION 8 Bcms moved to produce 8 Mtonnes of col Wste rock is removed nd plced in wste rock dumps to provide 290 Hectres for rehilittion. min pits re currently operting 00,000 cm wste rock re moved dily to four dump res

10 HISTORY Acid Dringe ws not considered n issue for the overurden when mining commenced in the erly 990s Sulfides nd AD potentil hd een recognised within the col wshings The first pit hd produced low AD genertion The next pit strted to generte AD in 99 from wste dumps (legcy dumps) Detiled testing of overurden ws undertken to determine AD potentil fter mine strt-up Retro-engineering to cp nd cover cid generting legcy dumps

11 E N V I R O N M E N T Acid dringe STUNTED VEGETATION AID DRAINAGE LEGAY DUMP

12 Acid dringe generted from exposure of sem roof nd floor

13 ULTURAL HALLENGE AD ws extensive with most of the dumps generting cid nd AD diverted to lrge holding ponds for tretment Needed to reduce to mngele stte the cid dringe within the site, reduce the cost of reprocessing wste dumps nd eliminte legcy dumps Needed to chnge the wy the mine operted with respect to its wste hndling In effect we hd to crete culturl chnge in the thinking of the mine mngement Assisted y smrt young geologist Deddi Hndiko nd supported y the Generl Mnger of Helth Sfety nd Environment Mtthew Orr

14 Acid dringe is low ph wter with dissolved metls nd sulfte tht drins from pyrite-rich rocks tht hve een exposed to oxidtion. pyrite + oxygen + wter cid + iron + sulphte

15 HISTORY Wste clssifiction complex 7 wste clsses sed on NAG ph Brod drill hole spcing used to define wste distriution - grid spcing m Blst hole smpling used to define hndling of wste Limited onsite l cpcity for testing lst holes smples for AD Short nd long term plnning of wste ws interpreted mnully to clculte the quntity of potentilly cid forming overurden Acid dringe ws common within the mine re nd wste dumps No dischrge to the environment hd occurred ontrolling cid dringe ppered impossile

16 URRENT Wste clssifiction simplified Detiled smpling for Wste definition in proposed pit res drilling grid 00m spcing omputer modelling of Wste used to define in situ wste rock distriution Wste smpled from lst holes to vlidte wste model in pit only L cpcity incresed to 00 smples per dy processed nd QA check y two offsite ls Wste model merged with resource model nd wste schedule for ROM generted for selective mining nd plcement of NAF nd PAF wste Mining Deprtment were encourged to tke responsiility for AD mngement

17 Acid dringe The pyrite is lrgely confined to specific sedimentry lyers

18 MANAGING WASTE Mngement of cid dringe needs knowledge of the distriution of pyrite within the mine sequence tht will e mined s wste rock Mngement of cid dringe is fcilitted through Wste Modelling, Plnning nd Selective Wste Hndling

19 WASTE MODELLING omines geologicl knowledge of the pit with wste geochemistry nd defines the Sptil distriution of non cid forming wste (NAF) nd potentilly cid forming wste (PAF) The wste model is like the col resource model it defines the distriution nd volume of wste rock types tht will e mined hnged from lock modelling to lyer modelling using geology nd geochemistry

20 Exmple of Previous Wste Grde Modelling Brown = High PAF Vlues grding to Blue = NAF Vlues ol sem

21 GAMMA LSD NAG Vlue SO I Z I Z S I Z M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M SN GAMMA LSD NAG Vlue S S M M M M M M M M M M M M M M M M M M M M M M M M M M M GAMMA LSD NAG Vlue M M M M M M M M M M M GAMMA LSD NAG Vlue SO BS BS I Z S S I Z S S S M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M Bsic Drillhole Dt ompiled to form the Dtse for the Wste Model INTERP LITHO LOGGED LITHO ALIPER GAMMA BRD NAG SAMPLES

22 GAMMA LSD NAG Vlue SO I Z I Z S I Z M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M SN GAMMA LSD NAG Vlue S S M M M M M M M M M M M M M M M M M M M M M M M M M M M GAMMA LSD NAG Vlue M M M M M M M M M M M GAMMA LSD NAG Vlue SO BS BS I Z S S I Z S S S M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M ol ol lssifiction of Lyered ol nd Wste Surfce topogrphy nd wethering defined y 2D grid surfces NAF NAF NAF ol sems nd NAF wste defined y roof nd floor elevtion s 2D grids. PAF PAF PAF

23 AD Lyered ol nd Wste Model onstructed BENH BENH PAF PAF NAF Surfce topogrphy nd wethering defined y 2D grid surfces ol Volumetrics held on lyer sis for ech mining ench,strip nd lock PAF BENH NAF ol NAF PAF ol sems nd NAF wste defined y roof nd floor elevtion s 2D grids. Other ttriutes such s thickness nd interurden my e computed from these surfces. The wste is constrined y the Sems

24 WASTE PLANNING The Mine plnning process for cid dringe mngement involves wste dump design nd scheduling overurden removl from pit for selective plcement Sufficient NAF wste is scheduled for encpsulting PAF nd plcement of finl cover for mnging ingress of oxygen nd wter

25 IN PIT VALIDATION A set of ench plns for ech Pit re is constructed showing NAF, PAF nd col The res of NAF re mrked out prior to lsting nd checked following lsting to ensure no PAF is mixed with the NAF

26 BLAST HOLE PROFILE

27 OVER DESIGN FOR OUT OF PIT DUMPS The covers re designed to minimise oxygen entering the dump nd therey minimise oxidtion of plced PAF wste rock The covers will only work if the correct mteril is used in their construction, this mens tht NAF must e crefully identified nd selectively hndled

28 OVER DESIGN Following the plcement of the PAF wste reducing the risk of AMD from the PAF wste is chieved y constructing cover over the dump from non-cid forming wste rock with or without compcted cly lyer.

29 OVER DESIGN The current dumps tht hve high degree of wste plcement control utilise the TYPE cover Legcy dumps hve een covered using TYPE 2 covers

30 Drwn y Drfting Section -Mining Services- Environt/Slope_Rev TYPE OVER over involves plcement of 0 metre un-compcted cover of NAF over PAF mteril with topsoil growth medium Topsoil >0m

31 TYPE OVER 0m Loose dumped NAF wste PAF wste MENTARI DUMP

32 Drwn y Drfting Section -Mining Services- Environt/Slope_Rev00.cdr TYPE 2 OVER This involves plcement of one metre compcted cly lyer over the PAF followed y 2 metres of loose dumped NAF followed y lyer of topsoil 2m m

33 TYPE 2 OVER 2 METRES OF NAF MATERIAL METRE LAYER OF OMPATED LAY MURUNG DUMP

34 MANAGING AID DRAINAGE WAS INTEGRATED INTO THE MINING PROE BY INVOLVING ALL DEPARTMENTS MINING OPERATIONS GEOLOGY AID DRAINAGE AID DRAINAGE GEOTEHNIAL MINE PLANNING ENVIRONMENTAL

35 The current mngement prctices for cid dringe hs ensured tht no Type 2 cover hs een required Acid dringe mngement is now integrl component of the mine opertion Acid dringe hs een gretly reduced nd is now mngele

36 THANK YOU