Engineering & Mining Journal

SEP 2018

Engineering and Mining Journal - Whether the market is copper, gold, nickel, iron ore, lead/zinc, PGM, diamonds or other commodities, E&MJ takes the lead in projecting trends, following development and reporting on the most efficient operating pr

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NARROW VEIN MINING SEPTEMBER 2018 • E&MJ 45 www.e-mj.com designs for CAF included drill patterns, suggested explosive loading and PFs. An example of LHOS design for an ir- regular vein shown in Figure 1.3. Reducing Dilution To target idealized dilution, AMC recom- mends closely monitoring three areas: drive dimension optimization, drill-and- blast practices, and overall quality control. For the ore drives, engineers should consider the narrower veins and purchase equipment that fi ts into 2.7-m x 3-m drift. They should also consider the use of shan- ty ore drive backs. Development into ore- body hanging wall should be minimized. Technical support processes for designing narrow vein stopes should be reviewed. As far as the blast design, engineers should consider large relief raises (i.e, V30-760 mm) for slot development. They should also reduce drill hole size and implement recommended drill patterns, including perimeter blast control. Guide rods should be used to reduce deviation. For stope blasting, low-density emul- sion should be used in narrow-vein stopes. Engineers should properly implement the stope (long-hole and ore drive) blast designs provided. Trial work processes should be developed to optimize the drill- and-blast patterns and reduce dilution. And, when it comes to ore quality con- trol, all departments (planning, surveying, geology, geotechnical, ventilation and op- erations) need to provide input and sign- off for stope and mine designs. The stope markup and reference line should be set by surveyors. A surveyed drill setup process should be implement- ed to improve drill hole accuracy. Blasting engineers should be involved continuous- ly with blasting crews. The cavity should be monitored and surveyed for every stope blast. Engineers need to perform regular, quantitative reconciliations between the design and the blast results. The results should be shared with stakeholders to justify implementing changes. Paul Salmenmaki is a senior mining engineer working with AMC Consultants. He can be reached at psalmenmaki@ amcconsultants.com. Figure 1.3—For ideal dilution, mine engineers should closely monitor drive dimensions, drill-and-blast practices and overall quality control.

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