I have recently finished work on a 'World Class' Cu-Mo-Au porphyry project, so I can give you an idea of the timescale and costs involved.
The deposit was discovered in 1957 and throughout the 1960's to the late 1990's it was explored by a number of junior to mid-tier companies before being picked up by a major. Major companies are not interested in doing exploration themselves, they want deposits that will fly handed to them on a plate with all the groundwork done and the final feasibility study completed. They optioned the deposit out to the company I worked for in 2005 and that company has borne all the costs of exploration, spending something like $150,000,000 over eight years (the exploration camp was costing over $1,000,000 a week to run during the field season). If the deposit had turned out to be a turkey, for any reason (poor grades, refractory ores, First Nations objections, etc) then the company, not the major, would have sunk.
Fortunately the deposit was a 1.3 billion ton winner and the company has recently signed a JV with the major, recouped their costs, handed the reins over and moved on to other projects. Start up costs for the open pit mine have been put at somewhere north of $2.5 billion.
While the ADL is certainly prospective, there is no data on the deposit that will pass modern reporting standards, so you're really at the start of the exploration cycle and it is very unlikely that ADL will feature on the radar of any major company. A listed junior is your best bet; someone to incrementally uprate the resource over a number of years with a view to passing it on if it reaches 'critical mass' in terms of tonnage and grade.
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