Well how did Brewery Creek manage it?
"leaching circuit effectively doubles the amount of ore under leach, resulting in increased gold production. Continued success at the Brewery Creek mine has proven for the third winter in a row that low-cost heap leaching can be used effectively in the Yukon."
"For the first time in many years, exploration expenditures for gold surpassed expenditures for base metals in the Yukon. Recent exploration successes in Alaska related to mid-Cretaceous intrusive rocks, namely the Fort Knox and more recently the Pogo gold deposit, has boosted exploration in Yukon areas hosting similar geology to the Alaskan discoveries. The potential in the Yukon for similar plutonic-related deposits to these Alaskan discoveries has long been known and was illustrated by the discovery in 1991 of the Dublin Gulch gold deposit near Mayo, the closest known match to the Fort Knox model. The plutonic related, low-cost, heap-leach Brewery Creek gold mine near Dawson has proven that these types of deposits can be economically exploited in the Yukon. Several senior mining companies conducted reconnaissance exploration programs (Fig. 9) in the mid-Cretaceous Tombstone belt, which resulted in the staking of several new properties. Other properties staked in previous years in this belt had exploration programs ranging from prospecting to diamond drilling."
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"The mine successfully produced gold during its first winter
of operation by using heap leach technology in the extremes of a cold northern climate. Gold production during the first two months of operation, November and December 1996, totaled 316 kg (10 175 oz). A total of 79 396 oz was produced in 1998 compared to a total of 72 387 oz of gold in 1997. A total of 11.8 Mt grading 1.13 g/t gold of mineable reserves remained as of May 1999. The eight low-grade oxide gold deposits at Brewery Creek are distributed over a 7-km-long linear trend underlain by Cretaceous Tombstone suite quartz-monzonite sills and Devono-Mississippian greywacke of the Earn group."
"WINTER HEAP LEACHING AT PEGASUS GOLD'S BEAL MOUNTAIN MINE:J.E. Micheletti, T.J. Weitz, Beal Mountain Mining, Inc., Anaconda, MT 59711
Pegasus Gold's Beal Mountain Mine is located near the Continental Divide, SW Montana. Conventional surface mining utilizes crushing, heap leaching, carbon absorption/desorption, electrowinning and refining to produce approximately 60,000 oz gold annually. A leach pad sits at 2,300 meters (7,500 ft) elevation. Winters are long and cold with average snow accumulations of 1-2 meters; temperatures fall below minus 40°C and wind chill temperatures below minus 70°C. The Beal Mountain staff has developed special tools and procedures for burying drip emitter lines, and managing the heap and process solutions to allow for uninterrupted gold recovery during the winter season. Management of water balance and spring runoff is critical to the operations' success, due to mountainous terrain, high precipitation and proximity to a fishery and elk herd. The mine has an extensive network of land application disposal (LAD) and stormwater control systems to assure environmental protection and regulatory compliance. "
OVERCOMING CLIMATOLOGY LIMITATIONS ON HEAP LEACHING: J.J. Komadina, Executive Vice President, Pikes Peak Mining Company, Victor, CO; R.R. Beebe, Consultant, Tucson, AZ 85751-2O48
Heap leaching of gold ores has enjoyed wide acceptance in the arid and semi-arid regions of the western U.S., Australia and South America. There are areas, however, where cold weather or excessive precipitation can limit the usefulness of heap leaching. Even in Nevada, difficulties can be encountered which call for special operating procedures. This paper discusses general climatological limitations and some of the techniques used to extend heap leaching into colder conditions. A case history of the Pikes Peak operation in Colorado examines "Valley-fill" technology as an ideal cold-climate solutions, where topographical conditions permit.
Project Description
The Kisladag Gold Project in west central Turkey will be the largest gold mine in Turkey when in full production. We have advanced the project from exploration and development to construction and production. Kisladag is a 14 year open pit heap leach gold mine. At full production the mine should produce 240,000 ounces annually. Cash cost of life of mine is US$232.
Location
Kisladag is located between the major centres of Izmir (180 kilometers to the west) and Ankara (350 kilometers to the northeast). Usak is the closest large population center, located 35 kilometers to the northeast, and access to the site is via all-weather paved roads servicing several small villages in the immediate area.
The project sits on the western edge of the Anatolian Plateau, in gentle rolling topography, at an elevation of approximately 1,000 meters. The climate is arid with hot summers and cold winters. Annual rainfall is approximately 460 millimeters, occurring mainly from November to May. Economic activity in the area consists of a mixture of subsistence farming and grazing.
Development Activities and Work Plan
Metallurgical testwork on Kisladag oxide and primary ore material in 1999 and 2000 suggested that heap leaching was the most viable approach to gold recovery. In 2001, we commissioned a Pre-Feasibility Study with Kilborn Pacific Engineers, which considered a first phase of mine development dealing with the oxide and primary ore contained in a 39 million tonne starter pit. This approach was taken to minimize capital expenditure in the early years and allow for later expansion of the project to develop the total resource.
After we completed a total of 31,000 meters of drilling on the Kisladag deposit, Micon International prepared a resource estimate in accordance with NI 43-101, which increased the Measured and Indicated and Inferred resources to 7.86 million ounces.
The results of this work were used to revise the resource classification in line with requirements for a Feasibility Study, completed in April 2003. The Feasibility Study has been updated over the course of project development to reflect changes in the mine resources as well as metal prices and changes in other market and regulatory conditions. The Feasibility Study Cost Update provided in May 2004 by Hatch reflected both technical and economic conditions going forward into mine construction. |
