Sep 15 2016
Dalradian Resources Inc. ("Dalradian" or the "Company") announces preliminary results from two test stopes at its Curraghinalt Gold Project in Northern Ireland. Stope 1 attained an average width of 1.40 metres, with estimated dilution to the designed stope of 29% and removal of an estimated 439 ounces of gold at a grade of 13.27 g/t from 1,029 tonnes of material. Stope 2 achieved an average width of 1.33 metres, with estimated dilution of 10% to the designed stope and removal of an estimated 973 ounces of gold at a grade of 24.34 g/t from 1,244 tonnes of material (see Table 2). These results are based on extensive muck sampling. The quantity of gold in Stope 1 was 36% above the resource model estimation, while Stope 2 exceeded the resource model estimation by 73% (see Table 1). The test stoping results validate the selection of long-hole open stoping as the primary mining method at Curraghinalt and demonstrate that narrow mining widths can be achieved using mechanized methods. These results will contribute to the feasibility study that is nearing completion.
Table 1: Comparison of contained ounces of gold between resource model, Dalradian grade control model and test stoping results
Table 2: Comparison of stope design vs. actual results
Patrick F.N. Anderson, Dalradian President & CEO commented,
"This is a great result from our test stoping program. The dilution and the widths achieved as well as the muck grade returned exceeded expectations. The better results achieved in Stope 2 reflect the experience gained from completing the first stope. There are only a few outstanding studies left before we can deliver on our feasibility study, which we expect to release on time this fall."
Key findings of the test stoping for the feasibility study include achievability of:
- Mechanized long-hole stoping
- Narrow mining widths of between 1.2 -1.8 metres
- Stope lengths of 20 metres
- 15 vertical metres or more between sublevels
The test stoping area is located approximately 60 metres below the surface on the V-75 vein at the deepest point of the current development (see figures 1, 2, 3 for location; all figures referenced in this news release can be accessed at http://www.dalradian.com/news-and-events/news-releases/news-releases-details/September-14-2016-News-Release-Figures). This location was selected as it was readily accessible for pre-production delineation drilling and had an adequate crown pillar. It also occurs beneath a shallow zone of partial oxidation. It was therefore considered representative of the deposit as a whole for the purposes of such a trial. Observed ground conditions are excellent, with rock breaking as expected during blasting and good rock fragmentation evident in the muck (see Figure 6).
The test stopes were adjacent areas along the V-75 vein. Stope 1 was 16 metres long and 15.7 metres high (see Figure 4), while Stope 2 was 20 metres long and 15.5 metres high (see Figure 5), showing potential for faster mine scheduling using longer stopes. Orica Mining Services aided in the design of the test stoping program, while CMAC-Thyssen worked alongside Dalradian staff in drilling and blasting the test stopes. The design of the stopes was based on 100% recovery of the vein using zipper drilling to reduce the amount of drilling, the powder factor and minimize dilution. The dilution anticipated by the preliminary geotechnical model was 41% on Stope 1 with a length of 15 m, whereas actual results were 29% dilution with a 16 m length. For Stope 2, the geotechnical model predicted 39% dilution on a length of 20 m, whereas actual results were 10% dilution (length unchanged).
Split shot, a selective drilling and blasting technique, was also tested. By first blasting and removing the waste and then blasting the ore, we observed that we can reduce the tonnage from development material sent to the mill by more than 50%. Split shot is used to minimize dilution and high grade the development ore and also to improve results for the mechanized cut and fill production method (see Figure 7).
Qualified Persons
Eric Tremblay, P.Eng., Chief Operating Officer, and Greg Hope, MSc, MAIG, Chief Consulting Geologist, Dalradian Resources, are the Qualified Persons who supervised the preparation of the technical data in this news release.
Underground development along the veins was sampled by the production geologist via chip panel sampling, across the full width of the face for each round on advance. Distinct geological zones were sampled separately (vein separate from wall rock), with a general minimum-maximum horizontal sample width of 0.10m to 1m and chip sizes approximating 3-4cm. Four to five kilograms of material was chipped with a rock hammer from two thirds the height of each face down to the sill, in volumetric proportion based on relative abundance of mineralization versus gangue. Sample locations were measured from a surveyed control point. Channel samples were saw-cut into the sills of the 170 and 150 western sublevels along the V-75 vein for comparison with face and drill hole sampling. Samples were submitted to ALS Laboratories in the Republic of Ireland.
Muck samples were taken continuously throughout the mucking process of each stope, at a frequency of 1 sample taken every two scoop buckets from the stope (each scoop bucket contains an estimate of 2.6 tonnes of muck). Sampling was done by the scoop operator, using a shovel to put muck into the individual sample bags, which allowed a representative sample of both coarse and fine rock fragments to be collected. Sampling was done by the same three individuals over the whole period of the program for consistency and the Production Geologist performed regular audits of the sampling technique. Sample bags were numbered in sequence representing the scoop bucket from which they were taken. The sample bags were tagged and secured by the Production Geologist and samples were submitted to ALS Laboratories in the Republic of Ireland. 240 muck samples were taken from Stope 1, totalling 1.83 tonnes of ore, or an average of 7.63 kg per sample. 238 muck samples were taken from Stope 2, totalling 1.62 tonnes of ore, or an average of 6.81 kg per sample.
Quality assurance and quality control procedures identified no material issues. Face, channel and muck samples were analyzed by a 50 gram gold fire assay with either an atomic absorption, or a gravimetric finish for samples initially reporting over 100.0 g/t gold.
ALS Laboratories is accredited by the Irish National Accreditation Board (INAB) to undertake testing, including for Ores and Minerals (INAB P9 703), as detailed in the Schedule bearing the Registration Number 173T, in compliance with the International Standard ISO/IEC 17025:2005 2nd Edition "General Requirements for the Competence of Testing and Calibration Laboratories".
Source: http://www.dalradian.com/