Recommendations by Sector

MINING

Energy Use

The U.S. mining industry is a very diverse industry, ranging from production and processing of metals, coal, and industrial materials such as soda ash. The total value of mining industry output was about $54 billion as of 2000. The mining process includes excavation, mine operation, material transfer, mineral preparation, and separation processes. These operations are relatively energy-intensive, with mining accounting for over 3% of total industrial energy use in the U.S. For the mining industry as a whole, energy costs represent over 15% of the total cost of production.

Mining is becoming increasingly sophisticated, with some mines now using smart sensors to identify areas to prospect, guide sophisticated equipment used in extracting minerals, and monitor air quality in mines. Also, remotely-controlled machines are routinely used in guiding large equipment in extracting minerals, moving product, and in various processing operations.

In Colorado, mining accounts for 18 percent of all electricity use in the industrial sector (almost 1800 gigawatt-hours of electricity per year) and includes coal, hard rock, soda ash, and uranium mining. As of 1999, the Colorado mining industry produced $2.8 billion of materials, employing around 5,500 workers.

Energy Saving Opportunities

Opportunities for energy savings in mining include improving exploration techniques; raising the efficiency of the drilling, excavation, extraction, and ventilation processes; and improving the efficiency of the grinding, crushing, milling, pumping, rolling, and smelting processes. Since mining involves the potential exposure of workers and the environment to a wide range of harmful substances from uranium and radium to cyanide, methane, and coal dust, in some cases it is possible to improve environmental and safety conditions along with improving energy efficiency.

Specific efficiency measures that are frequently found to be cost-effective include the following:

Exploration

• Use non-invasive technologies such as remote sensing and ground-based technologies to minimize exploratory digging and drilling.
• Use remotely-operated sensors and associated computer modeling techniques along with remotely-controlled digging equipment to assess a possible site as efficiently as possible. The aim is to maximize useful fact gathering about the site while minimizing time and energy in assessment.
• Use advanced techniques for assaying mineral content at exploratory sites so promising leads may be followed—and less promising directions may be avoided.

Excavation

• Large numbers of motors and pumps are used in the excavation process. Correctly sizing these motors and pumps, as well as selecting premium-efficiency units, will save energy as will use of adjustable speed drives (ASDs) in applications with highly varying load requirements.
• A common technique for cooling spaces in underground mines is to cool air at the surface, and then transport this air underground using fans and ducts. Moving cooling energy in this fashion is hundreds of times more wasteful than moving it via insulated pipes and pumps to fan/coil heat exchangers located in the mine itself. The closed loop used to pipe chilled water takes advantage of gravity to move water into and out of the mine, and water can contain 55 times more energy per unit of volume than can air. In addition, it is simpler and more efficient to insulate pipe than ducts.

Processing

• Large numbers of motors, pumps, and blowers are used for moving, crushing, and handling ores and other materials. Once again, energy can be saved by properly sizing and maintaining motor systems, using premium-efficiency motors, and using ASDs in applications with varying load requirements.
• Use oxygen-fueled burners rather than air-fueled burners in the smelting process, which reduces energy use and emissions.

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