Environmentally Safe Maintenance
Environmental compliance and employee safety are the goals for today’s modern, progressive worldwide mining operation. Regulatory agencies are enforcing current laws as well as passing new laws to remove harsh chemicals such as chromates and nitrates in maintenance products. These regulations will result in lawsuits for non-compliance, not to mention the liability suits from informed mine employees. No mining operation is excluded.
A new type of proactive preventative maintenance program using environmentally friendly vapour corrosion inhibitors (VCIs) is becoming a reality in major mining operations today.
VCIs are the assorted products that protect metal surfaces from attack by corrosive agents such as moisture, salty air, airborne acids and contaminants. They do this by conditioning the enclosed air with trace amounts of an inhibiting material. Protective vapours disseminate in the enclosed space through vapourization. The inhibiting process begins when the vapours contact the metal surface and condense to form a thin protective crystal layer one or two molecules thick. In the presence of even minute quantities of moisture or acids, the crystals dissolve and form a protective film between the moisture layer and the metal surface.
VCIs have been used by the United States Navy to help reduce misfires in its missile guidance systems. They are already used in numerous industries and have begun to be accepted in the mining industry as well.
Extreme environments exist around mining operations such as sulphuric acid drift that will attach to any metal surface in any remote area. Structural substrates, mobile equipment and parts storage areas are no exception. A large mining operation in Utah was losing dollars on stored parts and equipment due to corrosion. This is typical of most mining operations. Utilizing environmentally friendly VCI coatings, emitters, and packaging, this operation was able to bring previously wasted dollars back to the bottom line.
A major mining concern in San Manuel, Ariz., chose to halt operations in July 1999 at its US$2.5-billion facility due to the decline in copper prices. This complex entailed a smelter, acid plant, oxygen plant, rod mill, 51 km of underground tunnels, 12 locomotives, 500 tank cars, generation plants, cooling towers, and multiple fuel-powered equipment.
During shutdown, the company instituted the use of VCIs. Emitters were placed in all electrical enclosures. Fuel additives were used in all gas- and diesel-powered equipment. VCI additives were used in all hydraulic systems and water systems. VCI grease was used in all grease systems. All internals were protected by contact as well as the vapour phase action that reached all recessed areas. Exterior surfaces of equipment were coated with a waterborne VCI coating to protect substrates from the environment as well.
The same mining company used these procedures at some of its other facilities for preservation. Another mining company used these procedures to lay-up and preserve its operation in Plyas, N.M. Maintenance audits have shown there is no visible increase in the corrosion rate in all treated areas for the last 18 months at these facilities. (VCIs do not decrease existing corrosion, but significantly slow down further corrosion rate.)
The vapour corrosion inhibitors have been introduced into operating mines as well. Operations in Utah, Nevada and Minnesota are converting to vapour corrosion inhibitors as a “proactive” preventative maintenance program. Procedures were instituted in current preventative maintenance programs with no down time resulting.
These environmentally friendly VCI products and procedures are chosen by mining operations due to their cost-effectiveness and efficient delivery system. There is no need to remove VCIs before restart, and they provide up to 24 months of continuous protection. They do not contain nitrates, silicones, phosphates, and chromates. The VCI products meet Environmental Protection Agency and U.S. Mine Safety & Health Administration standards.
Independent testing laboratories have shown that when VCI emitters are used in electrical areas like MCCs (motor control centre) and switchgear, the contact resistance of relays and contacts remains much lower because they inhibit oxide and contaminant build-up on the contacts. Other tests have indicated no increase of leakage currents at any point on PC boards or electrical circuitry. Electrical failure would mean mine shutdown, and ultimately the loss of hundreds of thousands of dollars.
The worldwide mining industry is spending more energy on environmental compliance today, while keeping the worker safe. The use of VCIs can be a cost-effective way to improve compliance and safety.