Pretium’s Brucejack Mine produces 32K ounces of gold in March

by Keith Powell
View of Brucejack Mine in winter.

The Brucejack Mine. — Photo courtesy Pretium Resources Inc.

Pretium Resources Inc. (TSX:PVG) (NYSE:PVG) (“Pretivm” or the “Company”) is pleased to report first quarter 2018 production results and provide an operations update as ramp-up advances at the high-grade gold Brucejack Mine.

First Quarter 2018 Production Summary

  • 75,689 ounces of gold produced
  • 96.8% gold recovery rate
  • 261,443 tonnes of ore milled
  • 2,905 tonnes per day ore milled
  • 10.9 grams per tonne gold mill feed grade for March; average 9.1 grams per tonne gold mill feed grade for the quarter

“Gold production improved steadily through the first quarter, with 32,910 ounces produced in March. This result is attributed to the successful implementation of a number of operational improvement initiatives,” said Pretivm President & CEO Joseph Ovsenek. “Our grade control program has now been fully integrated into our mining process and the rate of underground development has increased to provide for additional stopes in our inventory. We are focused on continuing to increase grade to the mill in Q2, and we remain on track to deliver on our H1 2018 production guidance of 150,000 to 200,000 ounces of gold at AISC of $900-$700 per ounce of gold sold. We are building on our healthy cash position, and expect to achieve steady-state production by mid-to-late 2018.”

Grade Control Integration and Improving Production

The grade control program is a data-driven and iterative process that is being used to optimize stope shapes resulting in reduced dilution and optimized grade to the mill.  The program comprises drilling, sampling and local modelling with improved short-term grade prediction. March production results reflect the first impact of grade control integration into the mining process during the month. In the second quarter, gold production results are expected to continue to improve with the full integration of the grade control program.

The absence of operational grade control and limited stope optionality contributed to low gold production for the month of January. Gold production subsequently increased significantly in February with stopes planned for the fourth quarter 2017 and other higher-grade stopes coming online.

Infill Drilling

As part of the grade control program, infill drilling is required at 5-meter to 7.5-meter centers to refine stope location and dimensions prior to mining. Currently, three diamond drills and one reverse circulation (RC) drill are being used for grade control drilling, with 11,100 meters completed as of April 1st.

The RC drill is part of a trial program for underground drilling. The RC drilling provides a larger sample per meter and is expected to be faster and more cost effective than core drilling, which has been used for infill drilling to date.

Local Grade Control Model

A local grade control model, which is based on data from drilling, is now being implemented for stope optimisation in areas of near-term production. The model is informed by tightly-spaced infill drilling (with areas drilled at 7.5 meters or better) and has a resolution of approximately 2.5 meters. The local grade control model is being used for stope shape optimization and estimating production grade, and will ultimately be used for medium-term planning for future production areas.

Stope Ring Sampling

Another component of the grade control program, stope ring sampling, provides grade information on a ring-by-ring basis to refine the shape of the long-hole stope prior to mining. Long-hole drill cuttings are collected from each ring within a stope and assayed. Assayed data from each of the rings is then fed back into the stope design to refine short-term mine planning.

Mining

To improve access and build stope inventory, the rate of underground development has been increased to 700 meters per month, up from the 420 meters considered in the Brucejack Feasibility Study.  The development rate increase began in January and is expected to remain at an average of 700 meters per month during the duration of stope inventory build-up in 2018. A third long-hole drill is now on site to support development and provide for back-up.

Stope inventory is expected to increase to 10 to 12 stopes.  The availability of stopes representing a range of grades, including multiple higher-grade stopes, allows mining operations to optimize stope blending and provides alternative stopes for mining if required. The increased stope inventory will improve the management of production grades.

2018 Guidance and Mineral Resource estimate Update

Brucejack Mine is on track to achieve H1 2018 production guidance of 150,000 to 200,000 ounces of gold at an all-in sustaining cash cost of $900-$700 per ounce of gold sold.  Guidance for H2 2018 is expected to be given at mid-year with the full integration of local grade control in the short-term mining cycle and optimal stope availability for production as the mine approaches steady state.

Annual updating of the Mineral Resource and Mineral Reserve for the Brucejack Mine will be initiated in the fall.

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