Mining and Processing

Broken Hammer Mine Design

Wallbridge Mining Company Limited

RPA was retained by Wallbridge Mining Company Limited to complete an open pit mine design and optimization for the Broken Hammer copper-nickel-palladium-platinum-gold project in connection with a prefeasibility study.  The Broken Hammer Property is located near Sudbury, Ontario.

 RPA’s involvement with the Broken Hammer Property dates back to 2005, when we were retained to complete an initial mineral resource estimate and NI 43-101 technical report.  In July 2012, RPA updated the mineral resource estimate based on drilling results and a 30,000 t bulk sample.  RPA was then retained to complete a mineral reserve estimate and mine design for Wallbridge’s prefeasibility study. 

The Broken Hammer Property hosts Cu-Ni-PGE-Au mineralization, typical of footwall-hosted mineralization in the Sudbury area.  Mineralization occurs as veins and irregular masses in Sudbury Breccia matrix as well as sulphide disseminations, clots, and veinlets in quartz monzonite gneiss.

Gemcom’s Whittle software was used to model an open pit based on the Indicated Mineral Resources.  A designed pit with ramps, benches, and berms was modelled in Vulcan, and used as the basis for Mineral Reserves.  A total of 196,605 t of ore and 1,710,770 t of waste will be mined over the 12 month mine life.  The ultimate pit will measure 90 m in depth with an area of approximately 3.0 ha.

Using the ultimate pit and economic cut-off grade, a detailed production schedule was completed.  Mining will be carried out by a contractor utilizing conventional open pit methods at an average rate of 5,800 tonnes per day.  Bench heights will be six metres in waste and three metres in ore to allow for greater selectivity.  Run-of-mine ore will be loaded into haul trucks and delivered to the crushers.  The ore will be sampled for metal accounting through a sample tower prior to being transported to offsite processing facilities.  Waste rock will be hauled to the storage facility and low grade material will be stock piled for potential processing at the end of mine life.

The prefeasibility study, which was completed by RPA and Genivar Inc., estimated a positive pre-tax net present value using a discount rate of 8%, US$3.50/lb copper price, and US$1,600/oz platinum price.  The results of the prefeasibility study were published on SEDAR on November 27, 2012.

In September 2013, RPA completed an updated Mineral Resource estimate, based on additional drilling completed. RPA also completed an update of the pit design based on the updated resource model. As of 2015, Wallbridge Company Limited is operating the Broken Hammer pit.