Altamira Gold Corp. (TSX-V:ALTA, OTC:EQTRF) has announced that it has received the results of initial metallurgical characterisation tests on two composite drill core samples from the recently completed scout diamond drill campaign at the Maria Bonita target within its Cajueiro project in Brazil’s Pará state.
The gold projects explorer and developer said excellent assay results from the initial drill holes at Maria Bonita were sufficiently encouraging for it to immediately commission metallurgical tests on the mineralized material.
“We are very pleased with these initial test results as they show the potential for high gold recoveries in the 90% range for both saprolite and fresh rock,” Altamira Gold president and CEO Michael Bennett said in a statement. “Importantly, key leach reagent consumptions were low and the tests confirmed that the mineralization does not contain significant deleterious elements.”
READ: Altamira Gold gets more promising assay results from final batch of initial drill holes at Maria Bonita target in Brazil
“With these positive metallurgical results in hand, we will continue the planning of a follow-up drill campaign aimed at determining the size of the mineralized body,” Bennett added.
Highlights include:
- Cyanide leach in a 24-hour agitated leach test at a grind size of 80% passing the 75 microns (µm) screen recovered 92% of total gold content in a saprolite composite (oxide) sample, while the fresh rock composite sample recovered 90% of gold content;
- Drill assay composite head grades for the saprolite (1.2 grams per ton (g/t) gold) and fresh rock (1.1 g/t gold) correspond well with the laboratory head grades of 1.3 g/t and 1.07 g/t gold respectively; and
- Average cyanide (0.11 kg/t) consumptions were very low by industry standards (0.45-0.75 kg/t) as a result of very low sulphide contents in the mineralized material.
As a next step, the company said it plans to conduct preliminary tests on crushing and grinding characteristics plus the amenability of the leach dynamics to heap leaching.
Consulting metallurgist Ian Gordon Hall Dun, who has 45 years of experience as a metallurgist in Brazil, observed: "The main body of tests were conducted at a specialist laboratory in Brazil (Testwork Desenvolvimento de Processo Ltda) which is highly regarded for its evaluation of gold ores. Initial results show excellent gold recoveries from both the saprolite and hard rock samples in an agitated cyanide leach test.
“These initial results point successfully in the direction of a heap leach scenario with high gold recovery and modest reagent consumptions,” he added. “More laboratory testing will now be focused on that heap leach scenario."
The Cajueiro project is located about 75 kilometres (km) northwest of the town of Alta Floresta in the state of Mato Grosso in centralwestern Brazil. Cajueiro forms one of three key projects that Altamira controls in the region, the other two being Apiacas and Santa Helena.
Cajueiro has current NI 43-101 resources of 5.66 megatonnes at 1.02 g/t gold for a total of 185,000 ounces in the indicated resource category and 12.66 megatonnes at 1.26 g/t gold for a total of 515,000 ounces in the inferred resource category.
The Maria Bonita target is located approximately 7 km northwest of the Cajueiro resource area and is defined by a gold-in-soil anomaly which is at least 800 x 800m in size and open to the west. The central part of the anomaly returned gold values above 1g/t gold in soils.
Altamira Gold is focused on the exploration and development of gold projects within Western Central Brazil.
Contact the author at stephen.gunnion@proactiveinvestors.com