Published in the May 2006 American Longwall Magazine
Highwall mining has been a part of the coal industry since the late 1980s. Despite numerous technological advancements over the years, the highwall mining method has still not realised a respected seat at the coal industry table.
Pros and cons
As with all things, there are pros and cons (click here for table) in the contractual vehicles used to employ highwall mining technologies. The primary approaches are purchase, lease or a contract mining agreement. ICG ADDCAR Systems is one company that offers all of these alternatives to the mining industry.
One of the major pros of highwall mining is its record as one of the safest methods of mining. According to the Mine Safety and Health Administration, the 2005 NFDL rate was 0 for ADDCAR, 1.49 for surface mining and 5.2 for underground mining.
Future Trends – Operations
The more highwall mining becomes integrated into a long-term mine plan and synchronized with the equipment and reserves of the entire operation, the more it should contribute positively to the bottom line.
The industry requires a mental paradigm shift to move highwall mining from an afterthought to a recognized and key contributor to an integrated mining operation.
One company that has embraced this paradigm change is ADDCAR, which said the benefits of new attitudes can be evidenced in the 2005 productivity statistics from MSHA:(click here for table).
Highwall mined coal should always be low-cost coal because all the system does is mine coal. Customary deep mining costs related to roof bolting, ventilation, rock dusting and the like are not incurred in a highwall mining operation.
Likewise, expensive costs of overburden removal associated with surface mining operations are avoided.
Another innovation, trench mining, holds significant promise. In trench mining, a trench is cut with traditional surface mining equipment and a highwall system extracts the coal from both walls in the trenches. In the proper setting, both overburden removal and environmental impacts can be reduced. The Midwest coal fields are likely candidates for this method of mining.
Reserves
In the east, coal reserves continue to thin and are now found in relatively smaller pockets. In the west, the final highwalls will be from extremely thick seams. Outside the United States, many of the opportunities involve steeply dipping seams.
The technologies still need to evolve to fully address these changing market needs.
Markets
Highwall operations are typically conducted in conjunction with surface mining operations. Table 2 is a tabulation of surface-mined production and number of surface mines by region in 2005 (source: MSHA).
The primary growth in surface mining tons will come from the Powder River Basin, which is not historically the most amenable setting for highwall mining. The regions are listed in order of decreasing potential for highwall mining.
Outside the US, countries such as Australia, South Africa, India, Indonesia, Columbia, Venezuela, Russia, Mongolia and China (listed in descending order of opportunity) have significant highwall mining potential.
Future technology
Highwall mining will likely continue to have an “intermittent use” aspect to an operation because often times it is only applicable during certain phases in the life of a mine.
This creates continuous pressure to reduce the capital costs related to the systems. Intermittent use may become more of an issue in the east as existing reserves are further depleted. However, highwall mining presents numerous opportunities in mining areas previously abandoned, such as pre-SMCRA unreclaimed highwalls.
Super-thin seam mining technology is an opportunity for the future.
As the cost of surface mining increases in the western US, highwall mining should become more viable in the Powder River Basin. However, the highwall mining equipment may require modification to adapt to the large volumes and to become more flexible in connection with large-scale surface mining operations.
Markets such as India, Columbia, Venezuela, Indonesia and Australia require a system that can operate in steeply dipping seams. Again, this will require a new design with much greater pull forces.
Guidance technologies available today work exceptionally well. However, lower-cost alternatives should continuously be pursued.
Rosy future
The secret is out – highwall mining is a viable solution for the near-term organic growth in the coal industry. The exciting and emerging opportunities for coal utilization (liquefaction, conversion and hydrogen) should further increase the demand for coal.
Highwall mining can be a significant, reliable and low-cost future supplier for these growing needs.
