VANCOUVER (miningweekly.com) – Quebec-based diamond miner Stornoway Diamond Corp on Thursday announced that its first diamond sale would be held in Antwerp, Belgium, on November 14, two months ahead of plan.
However, the company tempered expectations, stating that the first diamond batch to be sold would include a higher proportion of small diamonds than expected, which could yield a lower-than-planned diamond price.
More medium-sized stones in line with bulk sample expectations could be recovered as the mill progresses toward steady state. Stornoway expects the size and quality of diamond sales to remain variable in the near term as the ramp-up continues.
During the second quarter, Stornoway's Renard operation processed 91 000 t of ore at an average grade of 123 carats-per-hundred-tonnes for attributable carat output of 111 600 ct. During September, the operation operated at an average rate of 1 792 t/d, which is about 30% of the full design, which was restricted owing to the dewatering circuit in the mill.
To date, Stornoway has recovered 21 special stones over 10.8 ct, with most being gem-quality. The company did not give their specific sizes.
According to Desjardins Capital Markets analyst Michael Parkin, the mill circuit used to dewater the processed kimberlite is proving to be a bottleneck. He noted that Stornoway management confirmed that the issue relates to the amount of fines remaining in the process water.
The analyst also stated that management had informed Desjardins that it was confident of identifying and installing a modification in time to achieve commercial production (60% of design for 30 days) before year-end, as originally planned.
Openpit mining has been progressing well, with more high-grade ore volume present than modelled, which is resulting in bigger and better stockpiles than initially planned. Recovered diamond grades have shown positive correlation with the project’s expected mineral resource grades.
Stornoway is scheduled to host an official opening ceremony at Renard on October 19.