··~-€~~;~ !--_. • .. -~- 'If " Royal Oak Mines Inc. - Yellowknife Division The Giant Mine Water License HlL3-0043 Submission in Support of an Application cy Royal Oak Mines Inc. to have the N.W.T, Water Board Renew the Water Use License for the Giant Mine September :1,1992 -1.~-~ ;. ~ •.:..,.._·~ -•·-• •• ·~ 'C 1.0 IDtrocluctioD This submission is in support of an application made by Royal Oak Mines Inc. on July 27,1992 to renew water use license# NlL3-0043. This license was isaued to Giant Yellowknife Mines Limited by the Northwest Territories Water Board on April Ol,1987 for the purpose of licensing the industrial use of water in mining, milling and associated uses at the Giant mine in Yellowknife. This license is scheduled to expire on April 30,1993. 2.0 Back9roW1d The first gold discovery in the Yellowknife area came nearly a century ago in 1896, when a prospector named Arthur Blakeney, on his way to the Yukon and the Klondike gold rush, found some rich samples not far north of where the Giant mine stands today. Blakeney, perhaps unwisely, continued on his way L O the Yukon; what happened to him no one seems to know. It wasn't until 1934 that the firs~ ma Jcr Ye~lowknife discoveries were made. By the next year, the shores o: Yellowknife Bay were dotted with the tents and hastil y ~r.rown up cabins of prospectors eager to get in on the action. Amo~ ~ them was C. J . Baker, better known as Yellowknife Johnny. In 1934 ne and h:s partner, Hugh Muir made an exciting find - the Burwash ?-'..l.ne proper~i·, but unfortunately this property proved to be only a sma:l depos:~ . The two of them persevered and later staked the 21 cr~gina: Gian~ claims in July of 193S. In August of 1937 Giant Yellowknife Mines was incorporated, but Baker's luck didn't improve for the next fe.. years of investigation and drilling on the property offered little encouragement. The property wasn't explored again unti~ 1941, when Donald w. Cameron, a veteran prospector re-examined a prc~ ir.enc quartz outcrop near the southeast boundary of the property. !-: was whil e conducting the task c! mapping the structurally complex geology c! the area that a consulting geologist, Dr. A.S. Dadsc~. specul ated that there may be a major shear zone underlying th~ area extending through the property to the east c f the Wes~ Ba:/ Fa~::.:., 1mo.. n as the Baker Creek Valley . An aggressive diamond dri:::. program conducted to test this theory resulted in a spectacular discovery which was far richer than anyone had anticipated. A staking rush ensued and plans were quickly adapted to bring this deposit, aptly ca lled the Giant Mine, into production. By May of 1948 the first gold bar was poured, and since then more than 7,000,000 ounces have oeen produced, valued at more than $900,000,000. During the 1960•s, two adjacent properties , the Lolor Mine, owned by Lolo:- Mines Limited and the Akaitcho Mine ( later called "Supercrest") , owned by Akaitcho Yellowknife Gold Mines Limited were developed. Through the exchange c: snares fer aevelopment dollars, Giant Yellowknife Mines acquired management control of Lolor Mines Limited, Akaitcho Yellowknife Gol d Mines Limited and the development company Supercrest Mines Limited. Toe Lalor Mine ceased production -- in 1948, while production at Supe=crest has bee~ sporadic since the mid 1980's. The Giant mine has been producing gold continuously for over 40 years and has accounted for SO\ of the 14 million ounces of gold produced in the Yellowknife area since its discovery in 1934. The discovery and development of the Giant Mine made the town of Yellowknife a familiar name the world over, and contributed to the jobs and the resources which supported and encouraged the growth that the town has encountered over the past 43 years. In 1986, Giant Resources of Australia acquired the controlling interest in Giant Yellowknife Mines Limited from Falconbridge Nickel Mines Limited. Subsequently in November of 1990 this controlling interest was sold to Royal Oak Resources Ltd. In July of 1991, Royal Oak Resources Ltd., Giant Yellowknife Mines Limited, Pamour Inc., Pamorex Minerals Inc, and Akaitcho Yellowknife Gold Mines Limited were amalgamated into a new corporate entity called Royal Oak Mines Inc. 3.0 Process Description The Giant Mine is operated as prima:-~.: y a~ underground mine although in past years ore has been recovere~ from a series of small open pits. The ore body has a strike lengtn of over 16,000 feet and is accessed through three shafts and~~~ ramp systems. Currently, only the "C" shaft is active and the centr£-l and northern portion of the ore body which are served from "C" Shaft are a l so accessed by the main ramp system to the base of the ore body. The southern portion is accessed from the bottom of the Al open pit by the "A~ ramp. Open pit mining operations were shut down in 1990. Underground mining is principally by mechanized cut and fil. !. technique. The surface layout of the minesite is shown in figure 3.1. A cross sectional view of the underground is shown in figure 3.2. Gold present in the Giant ore is assc =iated with the arsenic bearing sulphide mineral, arsenopyrite. The ore is refractory, meaning that the arsenopyrite mineral structure must be broken down and oxidized t o allow the effective recovery :::: tne contained gold. The arsenopyrite and other sulphide minera.L s ar<.? first concentrated by flotation. Tne flotation concentrates are tne~ roasted and leached in cyanide to achieve an overall golc recovery of 87.5\. The milling capacity of the ore processing plan~ at the Giant Mine is 1,300 tons per day with roasting capacity of 22C tons per day. A simplified mill flowsheet is shown 1n figure 3.3. Run of mine ore is crushed underground in a primary jaw crusher and then hoisted to surface through ":·· sna!t. to a surface coarse ore storage bin. Additional ore is truck hauled to surface through several underground ramp systems. The combined ore is then crushed and screened at a three stage surfac~ crusnin; plant with the minus 3/8th inch material being conveyed into tne mill storage bins. Ore is drawn off the mill storage bine into two parallel primary grinding lines each consisting of an 8' diameter x 10' ball mill - ~- ,...._. working in closed circuit with a spiral classifier. Water is added to the ore a-:: the feed end o: tne two ba_l mills. The spiral classifier is a particle sizing device using th~ specific gravity of 0 the ground ore particles to separate fine particles from coarae particle&. The coarse particles are returned to the primary ball mill to be ground again while the fine particles overflow the spiral classifier. The combined overflows from both spiral classifiers is then screened to remove wood chips and other debris that may interfere with later process equipment. The screened classifier overflow i s then subj ected to a processing step called flotation where under controlled conditions the sulphide minerals are separated from the ground ore slurry. The sulphide minerals contained in the Giant ore are principally areenopyrite and pyrite. The surface of these sulphide minerals is coated with copper sulphate which is added at the feed end of the ball mill. The copper ions selectively coat the sulphide mineral surfaces. A chemical flotation collector called xanthate i s added at the classifier overflows and attaches itself to the coated sulphide minerals. The xanthate has a high affinity for air which is bubbled through the flotation cells. A commercial frothing agent. called Dowfroth is added to the slurry at the chip screen and provides a strong stable air froth when air is bubbled through the slurry. The xanthate and the attached sulphide minerals attac:: tnemselves to these air bubbles and float t o the surface c : tn~ f l otation cell.. At the surface of the flotation cell, this s ulphide mineral rich froth is skirrwned into a concentrate launde:- an= collected for further processing. The flotation circuit is broken into two sections set in aeries. The first section is called the rougher circuit. Material that did not float off in the rougher circuit is reground in two parallel regrind circuits each consisting of a ball mili worki~g in closed circuit with a set of cyclone sizing devices. The fine particles contained in the cyclone overflow from these two regrind circuits are combined and subjected to a second flotatio~ circui~ called the scavenger circuit. Additional copper sulphate, xanthate and dowfroth are added to the regrind circuits. The f lotatio:, circuit is esse:1-. :..al~:,· .,_ pre-concentrating step enabling Royal Oak t o recover 9$~ c : tne gclc contained in the 1300 tons per day of ore milled in a sulpniae mineral concentrate that weighs 200 tons per day. The remaining llOC tons per day containing 5% of the gold are re;ected to the tailin9s impoundment area as what are called flotation tailings. The flotation concentrates from bot:1 the rougher and scavenger circuits are combined and dewatered in a circuit using a dewatering cyclone and a thickener. The wate:- i s returned to the grinding circuit as a recycle strearr.. The principa: gold bearing mineral contained in this flotation concentrate is arsenopyrite, which is an arsenic - iron sulphide. The gold is interstitially locked inside the arsenopyrite mineral matrix making .:.~ resistant to recovery without first destroying the arsenopyrite mineral structure, hence the term refractory gold. The breakdown c! the areenopyrite mineral matrix is accomplished in a two stage !luid bed roaster at high temperature.