Prominent Hill
| Prominent Hill | |||
|---|---|---|---|
| General information about the mine | |||
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| Information about the mining company | |||
| Operating company | OZ Minerals | ||
| Start of operation | 2009 | ||
| Funded raw materials | |||
| Degradation of | Copper / gold / silver | ||
| Degradation of | gold | ||
| Raw material content | 0.000058% | ||
| Degradation of | silver | ||
| Raw material content | 0.00031% | ||
| Geographical location | |||
| Coordinates | 29 ° 43 '10 " S , 135 ° 35' 0" E | ||
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| Location | Coober Pedy | ||
| State | South Australia | ||
| Country | Australia | ||
Prominent Hill is a copper - gold - deposit in the Australian state of South Australia . The owner is the Australian mining company OZ Minerals (formerly Oxiana). The first copper-gold concentrate was produced in February 2009.
location
The deposit is located in central South Australia approximately 130 km southeast of Coober Pedy and 130 km northwest of Olympic Dam . It is connected to the Sturt Highway by a 40 km long unpaved road , and the mining complex also has a runway, which Alliance Air serves as a scheduled service from Adelaide. The processed ores are transported away by rail. It is connected to the Australian power grid in Olympic Dam via a specially constructed 130 km high voltage line.
history
The deposit was discovered in 2001 by Minotaur Resources in a joint venture with Oxiana. This was preceded by exploration work by smaller companies based on geomagnetic data , which indicated a strong positive anomaly. However, drilling on this anomaly was unsuccessful in the 1990s. Minotaur combined this data with gravimetric data, which also detected an anomaly, but slightly offset from the magnetic one. Minotaur then drilled in the overlap area and encountered a large ore body under about 90 m of cover . In 2006 a feasibility study was completed and Oxiana, which at that time had taken over Minotaur, decided to mine the deposit. In 2007, the construction of the processing plant and the opening of the open pit began. The ore body was encountered at a depth of around 90 m in spring 2008 and the first ore was mined. The processing went into operation in October 2008 and produces copper-gold concentrate, which is sold to Asian and Australian smelters.
The originally planned lifetime of the mining operation is 10 years. The construction of the mine costing 1.08 billion AUD . However, a feasibility study for underground operation is currently underway , which could increase the lifetime of the pit to 20 to 30 years.
geology
The deposit belongs to the so-called iron oxide-copper-gold deposits ( English Iron-Oxide-Copper-Gold , IOCG) and is very similar in many properties to the huge Olympic Dam deposit . It is located in the Gawler Craton in an approximately 1,585 billion year old volcanic sedimentary rock sequence. The volcanic rocks belong to the Gawler Range Volcanic (GRV) - Hiltaba event. This means that the deposit is roughly the same age as Olympic Dam, although the latter is located in a granite of the Hiltaba Suite , while Prominent Hill is bound to volcanic rocks. The side rocks of the deposit show almost no metamorphic overprint.
A distinction is made between three geological zones in the deposit: the skarn- granite package in the hanging wall of the ore body, the hanging -wall-fault zone (HWFZ - fault zone at the contact with the hanging wall of the ore body) and the volcanic-sedimentary package, which consists of carbonate rocks and sandstones , Greywacke and mafic to intermediate volcanic rocks. The skarns in the hanging wall of the ore body carry sub-economic magnetite-sulphide mineralization. The Mesoproterozoic rocks of the Gawler Craton are overlaid by about 90 m thick Permian and Cenozoic sediments at Prominent Hill .
The ore body itself is an extremely hydrothermally altered breccia body that occurs in the HWFZ and the volcanic sedimentary rocks. The alteration is essentially a hematite alteration. The copper minerals are restricted to the hematite breccia bodies. These breccias were created by hot, hydrothermal fluids. It is the channels through which the fluids flowed through the rock. The copper-mineralized areas consist of a crystalline hematite-sericite-fluorite-barite-carbonate matrix, which is interpreted as filling open spaces between the adjacent rock caves. In addition, there is a zone with earthy hematite, which has no copper mineralization and is interpreted as the displacement of the adjacent rock by hematite at lower temperatures. Outside of the copper-mineralized breccia bodies, a halo of gold mineralization that is low in copper or free of copper occurs, which consists of hair-fine gold-bearing carbonate fragments.
The main mineral of the ore is hematite , as described , but no iron is extracted. The most important copper minerals are chalcosine , bornite and chalcopyrite , with pyrite , barite , fluorite , solid gold and uraninite ( pitchblende ) as ore minerals. In contrast to Olympic Dam, however, the uranium content is only around 50 to 100 g / t, so that extraction of this metal is not worthwhile.
The current reserves of the deposit are 79.2 million tons, but the ore body is open on several sides (including at the depth), so that it is hoped to be able to develop further proven resources in civil engineering in the future. The deposit's current resource base includes 1.9 million tons of copper, 3.7 million ounces of gold and 15.8 million ounces of silver. The average ore grade is 1.24% copper, 0.58 g / t gold and 3.1 g / t silver. In the gold-only areas, gold grades are around 1.1 g / t and copper grades below 0.3%, but local intervals of up to 20 g / t gold are observed.
Dismantling and processing
The deposit will be developed in open-cast mining, which will ultimately be 1.5 × 1.2 km in size at a depth of 500 m. The rock is broken up by blasting and then removed with three Liebherr 996 backhoe excavators and 18 Caterpillar 793 dump trucks. The ore extraction is around 8 million tons per year. The ore is heaped up according to the quality and sent to processing with a planned throughput of 1000 t per hour. The ore is crushed and ground up in several stages. Then it is floated, cleaned, thickened and the concentrate is drained in a press. The processing residues are deposited in a circular tailing basin. The concentrate is transported by road trains to the Wirrida loading station on the Central Australian Railway and from there to Darwin . A small portion of the concentrate goes to the Olympic Dam hut .
There are several types of ores: Chalcosine-Bornite, Bornite-Chalcopyrite, Chalcopyrite-Pyrite and Gold-only mineralization. These are processed separately. Depending on the type of ore, there will be different concentrate qualities with 54% copper (chalcosine-bornite), 34% copper (bornite-chalcopyrite) and 25% (chalcopyrite-pyrite). There will also be a copper-free gold-only concentrate. The gold grades will be 10 to 15 g / t each. The high-quality chalcosine-bornite concentrate will be produced first. In 2009, 110,000 t to 120,000 t of copper and 75,000 to 85,000 ounces of gold are to be produced in concentrate. The other ore types are to be processed later and will be stocked up for the time being. As a result, production will drop to 90,000 tons of copper per year in later years of production.