ernest henry mine versus aum

have a look at ernest henry. then have a good look at what aum have. with more drilling aum will have as much copper as ernest henry


MIM (MIM acquired the remaining 49% on 27 June 2002)
Reserves of 89 million tonnes at an average of 1% copper (as at 30 June, 2002)
Significant gold credits at 0.53 g/t
Average production of 100,000 tonnes a year copper and 125,000 ounces gold
Commenced operations in August 1997
Transition from contractor to owner operator for mining operations during 1999/2000
It plans to improve metallurgical performance and costs in the face of reduced headgrades in 2002/03
Awarded the inaugural Australasian Institute of Mining and Metallurgy Occupational Health and Safety Award for the development of an exceptional safety and health management culture
Ernest Henry's current mine plan extends to 2010, exploration drilling is being undertaken to extend mining
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Overview



The Ernest Henry copper-gold mine, located around 38 kilometres north-east of Cloncurry in north-west Queensland, was officially opened in October 1997. Commercial production commenced in May 1998.

The mine plant provides for up to 10 million tonnes of ore to be extracted each year from an open cut operation to produce approximately 360,000 tonnes of concentrate containing 100,000 tonnes of copper and 125,000 ounces of gold.

The concentrate is transported by road to Mount Isa, about 117 km west of Cloncurry, for smelting by Mount Isa Mines, which has agreed terms to purchase all of Ernest Henry's concentrate.

Some 3,500 people were involved in building the mine at a cost of $310 million, more than 10% under budget.



The Ernest Henry project has been a major catalyst for significant infrastructure development in north-west Queensland benefiting the project and other users in the region.

Infrastructure developments included a 115 kilometre water pipeline, electricity transmission lines, upgrading and conversion of Mount Isa's Mica Creek Power Station from coal to gas, a new airport terminal and improved air services for a remote region.

Ernest Henry took over the operation of mining activities from a contractor in December 1999, resulting in lower mining costs.

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History

The mine is named after the explorer/prospector/miner Ernest Henry, born in England in 1837, who founded Cloncurry.

He explored the district in 1866, in the company of Roger Sheaffe. Sheaffe went on to establish Fort Constantine, the first pastoral property in the district.

Ernest Henry subsequently discovered numerous copper deposits in the district including the Great Australia and Mount Oxide.

The Ernest Henry mine is located within the present day boundaries of the Fort Constantine pastoral property.

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Geology

The Ernest Henry copper-gold deposit lies within a south-east plunging breccia system developed in a sequence of altered, porphyritic, intermediate volcanic rocks.

The breccia body dips 30 to 50 degrees south south-east and lies between a hanging wall sequence of variably altered felsic volcanic rocks and a footwall sequence of carbonate altered mafic volcanic rocks and siltstone.

Economic mineralisation is hosted by a breccia comprising strongly altered and replaced felsic volcanic fragments in a matrix assemblage of predominantly magnetite, chalcopyrite and carbonate.

The magnetite, copper and gold minerals are thought to have been introduced to these rocks around 1500 million years ago as a result of the nearby intrusion of a large granite pluton. Fluids from the granite passed through fractures, altering and replacing some minerals and forming the minerals present in the ore body - magnetite, chalcopyrite, pyrite, gold, cobalt molybdenum, rare earth elements and low levels of uranium.

Mineralisation boundaries are commonly sharp and conform to the limits of brecciation and fracturing.

The combined thickness of the mineralised sequence is around 250 metres, the width averages 300 metres. The ore body is open at depth and to the south west.

The upper portion of the mineralisation is weathered and variably oxidised and is classified as supergene ore.

This zone extends, in places, to 150 metres below surface and comprises about 12% of the entire resource. Supergene mineralogy is complex with copper occurring as native copper, bornite and chalcopyrite. Due to localised enrichment some of the highest copper and gold grades are present in this zone.

In the primary ore, copper occurs as chalcopyrite and gold occurs mainly in the molecular framework of the chalcopyrite. Copper to gold ratios stay consistent throughout at around 1% copper to 0.5 grams/tonne gold.


Mining processes

The Ernest Henry deposit, being close to the surface, is amenable to low cost, large scale open pit mining methods.

Over the 15 years of the currently planned mine life, in excess of 700 million tonnes of ore and waste will be mined. The pit will be mined in eight stages. Each stage will see the perimeter of the pit expanded and the overall depth of the pit increased. On current designs, the final pit will have a perimeter of 5 km, a diameter of 1.3 km and a total depth of 570 metres.

The scale of the mining allows large equipment to be used. The rock is drilled using rotary production drilling rigs. The rigs drill 17 metre deep holes of 270 mm or 311 mm diameter. Individual firings blast up to 500,000 tonnes of rock at a time.

The broken rock is loaded into 220 tonne capacity dump trucks by either a diesel-hydraulic shovel with a bucket capacity of 30m3 or an electric rope shovel with a bucket capacity of 43m3.

The 220 tonne dump trucks drive up a ramp at a gradient of 10% to deliver the ore to the crusher or waste rock to the dumps.