Gold producer Sunridge Gold has completed a strategic production study that examined the metallurgical characteristics of four resources at its wholly owned Asmara mine, in Eritrea.

The study, carried out by consultancy PEG Mining Consultants, included a high-level evaluation of the economics and the possibilities of combining the development of the deposits. Further, it also focused on examin-
ing the possibility of fast-tracking a high-grade portion of the copper supergene zone at the Debarwa deposit, in the southern part of the project area, into production by selective mining and direct shipping of the material to a smelter.

The results of the study will serve as a road map for Sunridge for future engineering studies 
and project development. As a result of the positive conclusions of the study, the company 
intends to start prefeasibility studies for the Emba Derho, Adi Nefas and Debarwa deposits in the near future.

The three mineral deposits held by Sunridge together contain indicated resources of 580 000 t 
of copper, 1,13-million tons of zinc, 1,05-million ounces of gold and 31.8 million ounces of 
silver. Further, the Gupo Gold deposit contains 189 000 oz of gold in the inferred category.

Further, the study also examined the concept of the combined development of the Debarwa deposit and the other three properties to the north, all located within about 
7 km of one another.

PEG has found that it is possible to selectively mine a high-grade, 15%-copper portion of the Debarwa copper supergene zone for direct shipping to a smelter, known as a direct shipping option (DSO), thus eliminating the need for a process plant facility early in the mine life.

Following the DSO start-up period, a flotation plant and further mine development would be required to exploit the remaining transition, supergene and primary zones at Debarwa.

Further, this nine-year-term production 
scenario improves the economics of the deposit. 
Trade-off studies by PEG mining engineers have also concluded that underground mining using a ramp, as opposed to using the existing vertical shaft, is the preferred method of access 
to the mineralised material at Debarwa.

Meanwhile, recent mineralogy and metallurgical testwork indicates that copper and zinc mineralisation from the Emba Derho, Debarwa and Adi Nefas deposits all respond to extraction by froth flotation in a similar manner and, therefore, coprocessing these materials in a single flotation process plant is deemed feasible. 

The company also reports that oxide gold mineralisation from all four deposits 
responds well to gold recovery by cyanidation, which means that this material could be copro-
cessed in a single central cyanide leach plant.

The company also points out that a central 
process facility for both base metals and gold at Emba Derho will provide significant economic 
benefits for the other three deposits through capital cost synergies for items such as process 
plant equipment, infrastructure and tailings 
disposal facilities.