Date: December, 2007
Location: Chevron Mine Draw Points, Questa New Mexico
Contractor: Smith's Waterproofing, Almont MI
Engineer: Kevin Sparks P.E., Chevron Mining Corporation
Mining shafts are constructed by blasthole drilling, boring equipment, and shaft-sinking machinery. The reinforcement of these shafts usually includes metal horizontal components (buntons) and vertical components (conductors) to ensure the smooth operation of skips and cages.
In this case, Fortress Carbon Fiber Grid was used to reinforce the mine shaft illustrating the usefulness and applicability of carbon fiber in this industry.
Most mines have various levels. The top level is usually where blasting occurs, and the level(s) below act as a funnel to extract mining material. A Draw Point is an entry point to retrieve material. These Draw Points are poured in place with a small tolerance to fit bucket machinery and are usually in a classic arch design.
Each Draw Point is affected by 40 lb blasts of TNT once a day. Steel reinforcement would add to the problem of removing sheared draw point material. Smith's Waterproofing reinforced 2 Draw Points with Carbon Kevlar Grid for testing. Carbon Kevlar Grid was surface mounted on one Draw Point in a 2 ft on center checker grid pattern, while on the second it was installed in 1 ft on center pattern.
The closer pattern survived days of blasting before showing signs of damage, while the 2 ft pattern began to shear on the first blast. Also surface mounting needs to be protected from scrapping of the bucket machinery. However, Carbon Fiber has a big future in Mining Draw Points. We are now in the process of designing a product to meet these specific needs.