Name: Soledad Mountain mine.
Location: The Soledad Mountain mine project is located in Kern County, in southern California, in the US, about 8 km south of the town of Mojave.
Controlling Company: Golden Queen Mining.
Brief History: Golden Queen Mining Co Ltd was formed in November 1985 to acquire Golden Queen Mining Co Inc, a Californian corporation, which had secured, by agreement, a core group of claims on Soledad Mountain.
Brief Description: The operation has been designed to mine an estimated 5.1-million tonnes of ore and associated waste rock a year. The permitted combined ore and waste mining rate is 14-million tonnes a year. Gold and silver production is projected to average about 77 000 oz/y and 890 000 oz/y respectively, although this is expected to fluctuate from year to year depending on the ore head grades. Gold and silver production is projected to be an estimated 1.07-million ounces and 1.2-billion ounces respectively over 15 years.
Geology/Mineralisation: Soledad Mountain is located within the Mojave structural block, a triangular-shaped area bounded to the east by the north-west-trending San Andreas fault and to the north by the north-east-trending Garlock fault. The Mojave block is broken into an orthogonal pattern of N50E to N60E and N40W to N50W fracture systems. These fracture zones likely developed as the result of Late Cretaceous compressional stresses that were present before the formation of the Garlock and San Andreas faults.
Gold and silver mineralisation at Soledad Mountain is hosted by north-west-trending, en-echelon faults and fracture systems. Cretaceous quartz monzonite forms the basement of stratigraphic sequences in the Mojave block. The quartz monzonite is overlain by Miocene-age quartz latite and rhyolitic volcanic rocks. Volcanic centres appear to have formed at intersections of the north-east- and north-west-trending fracture systems. Major volcanic centres are present at Soledad Mountain, Willow Springs and Middle Buttes. These volcanic centres consist generally of initial widespread sheet flows and pyroclastics of quartz latite, followed by restricted centres of rhyolitic flows and rhyolite porphyry intrusives. Rhyolitic flows and intrusives are elongated somewhat along north-west-trending vents and feeder zones.
Reserves: Total proven and probable reserves as at August 31, 2012, were 60.61-million tonnes grading 0.644 g/t of gold and 11.77 g/t of silver.
Resources: Total measured and indicated resources as at February 29, 2012, were 144.82-million tonnes grading 0.517 g/t of gold and 9.42 g/t silver. Inferred mineral resources are estimated at 14.55-million tonnes grading 0.362 g/t gold and 7.89 g/t of silver.
Products: Gold and silver.
Mining Method: The project will use conventional openpit mining methods and the cyanide heap-leach and Merrill-Crowe processes to recover gold and silver from crushed, agglomerated ore.
Major Infrastructure and Equipment: Wheel loaders and haul trucks, with a capacity of 90 t, will be used as the primary mining equipment. Smaller equipment will be used for pioneering access roads, mining narrower benches, and final ore extraction at the bottom of the various mining phases. Support equipment, such as a grader, a water truck, a wheel dozer and tracked dozers will be used for road and bench maintenance, dust control and work in the waste rock disposal areas.
Ore will be fed to the mine’s crushing-screening plant. The plant includes a primary and secondary crusher and screen in closed circuit with the secondary crusher. A high-pressure grinding roll (HPGR) will be used as part of the crushing circuit to prepare the ore for stacking on the two leach pads.
The HPGR consists of two counter-rotating rolls – one a fixed roll and the other a floating roll. The floating roll is mounted on and can move freely on two slides, with the grinding forces applied by four hydraulic rams. Ore is choke-fed to the gap between the rolls.
Prospects: The Soledad Mountain mine project is proceeding on schedule, with processing facilities set to be commissioned in late 2015.
Contact Person: President and CEO Lutz Klingmann.
Contact Details:
Golden Queen Mining,
tel + 1 604 921 7570, and
email lklingmann@goldenqueen.com.