South Railroad Project – Updated Preliminary Feasibility Study – Resources and Reserves
Gold Standard Ventures Corp. (“GSV”) is an advanced stage, gold exploration company focused on district scale, gold discoveries in Nevada. GSV contracted with MDA/RESPEC and other consultants to update the Railroad Project Prefeasibility Study in late 2018through early 2019. This built on previous work in which MDA/RESPEC was involved over the past few years. The main prefeasibility was compiled with M3 Engineering as the lead and MDA/RESPEC provided definition and signature of Mineral Resources and Mineral Reserves following Canadian Institute of Mining (“CIM”) definition standards. The results of the study were published in a Canadian NI 43-101 Technical Report: “South Railroad Project, Form 43-101F1 Technical Report, Updated Preliminary Feasibility Study, Elko County, Nevada”.
Reporting Mineral Reserves requires collaboration with other engineers and consultants to identify modifying factors that are applied to the resources. These modifying factors include consideration of land and legal issues, permitting requirements, metallurgical and processing requirements, geotechnical design requirements, pit and waste rock storage facility design, road design, equipment, and many other factors. The determination of reserves is an iterative process, requiring pit optimizations, pit design, waste dump design, and road design. These were done for each deposit from which a combined production schedule was created for the project.
The pit optimization was done based on geometrical and economic parameters. The geometric parameters included land boundaries and slope parameters which defined the angles to be used for the pit walls. Pit optimization started with assumed walls based on input from geotechnical engineers. The pit was designed based on the slope parameters provided. Due to the placement of haulage ramps, the final pit will likely be a bit flatter than the original parameters used. A second iteration of the pit optimization was done based on the measured slopes from the design. This was then compared back to the pit design and the design will be adjusted as needed. All pit and dump designs were completed using Surpac software.
The pit design also incorporates interior pit designs to act as initial mining phases. These phases were designed around smaller pit optimizations that allow more valuable material to be mined earlier in the schedule. The tonnes and grades are tabulated inside of the design to be reported as reserves. The resulting waste volumes were also tabulated and used as targets for the dump designs. These dump designs were also sequenced so that nearer portions of the waste dumps are filled first and then in a logical sequence outward. This reduces the costs early in the mine life, and while the costs increase later in the mine life, the time value of money is increased.
The production schedule was the primary input into the metallurgical recovery model as well as the economic analysis. MineSched was used to create the production schedule using the pit and dump designs as mining and fill locations. Material types were created to differentiate where material was to be sent and report the timing of ore placed on the run-of-mine pad as well as sent to the crusher. The haulage profiles were developed in MineSched to calculate the haulage hours required for the schedule.
Equipment and personnel requirements were developed in order to estimate the mining costs. These costs were detailed into drill, blast, load, haul, support equipment, mine maintenance and mine general. These costs were developed from first principles, meaning that the hours for the equipment were estimated, then costs per hour for the equipment were used to estimate the overall costs. The estimation of equipment hours considered standby, delay, and efficiency assumptions. The personnel requirements were simply an estimate of the personnel, operating, supporting, and supervisory required to operate the mine.
The mine capital estimate included the equipment costs based on vendor quotations along with other items required for the mining operations including roads, explosive silos, explosive magazines, radios, office equipment, survey equipment etc. The goal on the prefeasibility study was to provide costs estimated with an accuracy of -15% to +20%.
The culmination of this work is documented on Sedar.com for those interested in further details.