The latest hammer mill batch from Orinoco Gold’s (ASX: OGX) Cascavel gold project in Brazil has continued to impress with gold grading up to 40.74 grams per tonne returned in the fifth campaign.
This latest fifth campaign contained six samples totalling 9.25 tonnes that produced gold grading 40.74g/t, 31.85g/t, 30.45g/t, 16.71g/t, and 8.31g/t.
To-date, samples have returned an average gold grade of 36.17g/t, with the latest campaign averaging 25.91g/t.
Meanwhile, the larger hammer mill has now been installed and will be commissioned today, with production ramping up to 25 tonnes per hour by Tuesday.
“We are quietly confident the much larger hammer mill 3 can deliver the same kind of recoveries and grades as the two smaller mills,” Orinoco managing director Jeremy Gray said.
“It is also comforting that the underground performance is really taking shape which should support our ‘Back to Basics’ target of delivering consistent low cost ounces week in and week out,” he added.
In mid-January, Orinoco reported a bonanza 265g/t gold from Mestre had been recovered from the hammer mill pilot.
The hammer mill pilot program is part of Orinoco’s “Back to Basics” approach, which was developed after initial mining and processing failed to recover economic gold ounces.
After a review, this was attributed to the gravity circuit being unsuitable to the finer gold particles that were typical of Cascavel.
Orinoco’s team came up with the hammer mill processing method as more suitable to the project’s finer gold.
The hammer mill can crush the ore into smaller particles and enables far larger gold recoveries.
In late November and mid-December last, this method was trialled on Cascavel gold for the first time with more than 90% of the precious metal recovered grading between 30g/t and 149g/t.
In addition to the higher gold recoveries, Orinoco broke through the Mestre access and Mestre decline to reduce the haulage route, resulting in lower bogging machine cycle times, decreased fuel costs and machine wear.
Trial mining at the Cuca deposit within Cascavel is scheduled to begin later this month, which, if successful, will progress to commercial mining by April.
Hammer Mill 4, which also has 25tph capacity, is expected to be commissioned next month to boost operations.
Shares in Orinoco lifted more than 2% to A$0.083 in early morning trade.