Alpala now has an indicated and inferred mineral resource estimate of 2.95 billion tonnes at 0.52% copper equivalent, for 15.4 million tonnes contained copper. 

This is a 108% increase in the contained metal compared to the previous resource, which came out in January. 

Alpala has 8.4Mt copper and 19.4 million ounces of gold in the indicated category. 

The high-grade zone - with 0.96% copper cut-off instead of 0.2% - also doubled to 420Mt at 1.47% copper. 

SolGold CEO Nick Mather said there was more to come from Northern Ecuadorian project. 

"Alpala has got more to grow yet and we are pursuing that aggressively over the coming months," he said. 

The new resource estimate comes from another 80,000m of drilling at Alpala this year. 

The company said the 0.2% copper equivalent cut-off showed "high production rate mass mining methods such as block caving" could be part of the preliminary economic assessment for the project. 

Hannam & Partners director of mining research Roger Bell noted the company had used the end of October as a resource cut-off, meaning only around 82km of the expected 118km of drilling was included.

"In our view, this suggests more tonnes could yet be added as further assays are returned, not to mention the multiple high-potential drilling targets at Cascabel which have been identified for the 2019 program," he said. 

SolGold said growth would come in 2019 through drilling at Alpala SE, Alpala NW, Trivinio and Alpala Western Limb. 

In the northwest-Trivinio area of Alpala, SolGold reported intersections of 402m at 0.65% copper equivalent, including the discovery of a new zone, north of the Alpala Breccia unit, containing primary bornite mineralisation of 162m at 0.95% copper equivalent. 

A preliminary economic assessment is due in January.

"This will provide the first firm guidance on the potential scale, development capex and operating costs for the Cascabel/Alpala project," Bell said.

Bell has provisionally estimated an internal rate of return of 22% and discounted cashflow of around US$2.2 billion, based on a 16Mt per annum block cave operation and copper price of $7000 per tonne.

He left his 80p price target unchanged. SolGold shares closed at 37.60p in London.

Over September and October, BHP spent nearly $120 million to acquire an 11.2% stake in SolGold. 

BHP chief financial officer Peter Beaven was questioned by an analyst during a presentation in Melbourne this morning about whether the major had enough growth options.

He said the company had "more or less bought all of our resource bases" and reiterated it was keen on copper and oil opportunities.

Beaven made it clear BHP had a cautious approach to M&A.

"Of course it has a part to play," he said.

"But M&A is hard because you still have to pay the market price, then get a return."

BHP is now the company's second-largest shareholder, behind Newcrest Mining.

Newcrest managing director Sandeep Biswas said at the time he was fine with another big company getting involved in the project. 

"If Cascabel develops to the extent we'd all like it to - we'll have to see whether it's going to get there - it's going to be a big mine with a lot of investing capex, so in relation to developing a mine in the future, there's no question there can be more than one company accommodated in terms of those developments," he told reporters.