VANCOUVER (miningweekly.com) – Project developer Dalradian Resources now has 32% more mineable gold ounces at its flagship Curraghinalt project, in Northern Ireland, after its undertook a sensitivity study on two of the best veins at the project.
The TSX- and Aim-listed junior used a revised resource modelling approach on the T17 and V75 veins. resulting in a 37% increase in grade and a 10% increase in ounces.
In the new study, the geology wireframes were remodelled using assays, with a heavier emphasis on logged geology. This approach yielded 24% narrower veins, accompanied by a 20% decrease in tonnage. The composite length was adjusted from 0.5 m to 0.3 m, to reflect the narrower domains, but all other parameters remain unchanged, with the aim to isolate the impact of re-wireframing.
Dalradian assessed the impact of the revised modelling methodology on potentially mineable material for the two veins by applying the same parameters as those used in the December 2016 feasibility study (FS). It was found that the revised vein block models resulted in a higher potentially mineable tonnage of 34% and a corresponding increase in mineable ounces of 32%, at the expense of a marginal decrease in grade (1.5%).
“The resulting shapes for the T17 and V75 veins are more heavily influenced by geology as opposed to previous models which were largely grade driven. This has resulted in smoother, higher-grade veins that are only slightly narrower than in the previous model. The implications are that we can use long-hole mining methods more extensively and bring new ounces into the mine plan, which had previously been below the cutoff grade,” president and CEO Patrick Anderson stated.
“The bottom line is that we have 32% more mineable ounces for the two veins tested."
This change in modelling sequence, where wireframing is carried out on geology and assays, followed by compositing within these wireframes, can in part explain the positive reconciliation between mill and resource (42% more ounces) resulting from the test stopes completed in 2016, the company advised.
An internal grade reconciliation study, completed in August 2016, showed a 13% higher grade on a portion of the V75 vein than was estimated in the May 2016 resource model. The grade control model was based on much tighter-spaced drilling and a higher number of on-vein face and channel samples.
In May, Dalradian reported positive results from processing nearly 14 500 t of mineralised material from three test stopes on the V75 vein, which was completed during the latter half of 2016. This yielded a gold grade 40% higher than modelled in the May 2016 resource estimate.
Further, material from development along five different veins, which was explored underground in 2015 and 2016, yielded a gold grade 6.6% higher than modelled in the May 2016 resource estimate.
These studies demonstrate that, as the drilling and sampling density is increased at Curraghinalt, the grade also increases. This pattern is also evident in the resource estimate, where the grade increases from inferred to indicated, to measured categories, as drill spacing and confidence increase.
Dalradian plans to drill 40 000 m in 2017. The main goal is to convert inferred ounces to the measured and indicated categories, so that they can be incorporated into the mine plan. A secondary goal is to show better rock conditions than assumed in the feasibility study, thereby increasing the amount of long-hole mining (66% in the December 2016 feasibility study) in the mine plan.
There are currently five surface rigs and three underground rigs on site.
Work continues on the environmental and social impact assessment report that, along with a project description based on the December 2016 FS, will form the basis of a planning (permitting) application. This application is expected to be submitted before the end of the year.Creamer Media Deputy Editor