Sandspring Resources has announced positive results from a preliminary economic assessment (PEA) of its Toroparu gold project in the Mazaruni-Cuyuni district of northwest Guyana. The conclusions and results of the study update and replace a 2013 prefeasibility study.

The Toroparu project has been re-scoped to include the Sona Hill satellite deposit and modification of the project’s processing strategy to start with gold-only production from a carbon-in-leach (CIL) circuit for the initial 10 years, followed by an expansion in year 11 to add flotation processing capacity.

Key aspects of the PEA include total production of 4.5 million ounces (oz) of gold over a 24-year mine life. Production during the initial 10 years would total 1.5 million oz in gold doré bars, followed by 14 years of operations that would produce 2.2 million oz in doré bars and 876,000 oz of gold in concentrate.

Preproduction capex to develop the Toroparu project is estimated at $378 million. Payback is estimated at 2.9 years.

The $232 million phase 2 expansion would be financed from internal cash flow.

During phase 1, gold and by-product silver would be produced by processing through an 11,500-mt/d carbon-in-leach circuit fed at mill head grades ranging from 1.67 g/mt to 1.2 g/mt gold. During phase 2, processing throughput would increase to 23,000 mt/d based on introduction of an 11,500-mt/d flotation circuit.

In addition to life-of-mine production of 4.5 million oz of gold, Toroparu production would include 4.46 million oz of silver and 124.7 million lb of copper as by-products.

Mining will be based on conventional open-pit methods from three pits: Toroparu, SE Zone (1.2 km southeast of Toroparu), and Sona Hill (4.9 km southeast of Toroparu). Mining operations are planned to begin during the second year of construction at a rate of 8 million mt/y, increasing to 20 million mt/y by production year three, 32 million mt/y by year 10, and 42 million mt/y by year 15.

Material containing higher sulphides will be stockpiled for feed into the flotation circuit beginning in year 11. Rehandling of stockpiled mineralized material will be accomplished with wheel loaders and trucks. Production in years 23 and 24 is planned to be from stockpile rehandling only.

“The re-scoping study shows the significant changes to the profile of the Toroparu project that have occurred since the 2013 prefeasibility study was issued,” Sandspring CEO Rich Munson said. “With a reduction of preproduction capex by more than $120 million, an increase in total gold production, and an upfront monetary deposit based on a precious-metals purchasing agreement with Wheaton Precious Metals, the economics of the re-scoped project compare favorably to those of the 2013 prefeasibility study even though they are modeled at a gold price that is $100/oz less than the 2013 prefeasibility study.”