Kaishan USA | January 24, 2023 | Uncategorized
The Kalgoorlie Super Pit, one of Australia’s largest open-pit gold mines, is more than three miles long, a mile wide and 650 yards deep.
Mining and compressed air have a long and distinguished history, with many of today’s leading air compressor manufacturers getting their start in mining. They began by making air compressors to power their drilling equipment. And thus initiated a close tie between the two.
Some manufacturers, including Kaishan, continue to make products for the mining industry. In our case, a sister company still makes drilling rigs and drilling equipment sold in many locations around the world.
This long-term, mutually beneficial relationship between the industry and the technology gives air compressor manufacturers deep insight into the needs of their mining customers. As a result, compressed air supports the sector at almost every step in mining and mineral recovery.
Air compressors offer mining and mineral processing operations several critical benefits:
Mines can run thousands of feet below the surface, making it challenging to supply breathable air.
One of the most important uses of compressed air in mining is in providing the ventilation that saves lives.
The U.S. Department of Labor’s Mine Safety and Health Administration requires that mining operators always make breathable air available to miners. It lists compressed air as one of a few possible sources.
Mining equipment and ventilation system in a coal mine.
Some of the compressed air piping can be miles long, reaching deep mine tunnels and refuge bays that protect miners and give them shelter during emergencies or fires.
Air compressors, vacuum pumps and blowers are also used to extract lethal methane gas, keeping it from building up and causing breathing problems.
Kaishan recently helped a Canadian gold mine develop an emergency air application for shelters thousands of feet below the surface, using compressor power to remove carbon dioxide and other contaminants and replace it with fresh air and oxygen.
Because of their longstanding presence in the mining industry, air compressors play a role in all areas of the mining industry.
Compressed air provides the power to drive rotating drill bits and other mining equipment.
A jumbo drilling rig used in an underground mine.
Power wrenches, drills, hacksaws and a wide range of hand tools rely on compressed air for their power source, avoiding electricity use.
Compressed air is used throughout the smelting and refining processes, helping the mining company extract the product from ores. It generates the bubbles coming out of the spargers, the porous devices at the bottom of a settling tank.
A flotation pool at a copper mine near Tucson, AZ.
Low-pressure air is used in flotation cells to help separate metals like chrome, copper, lead, aluminum, zinc, platinum and gold from the slurry. High-velocity air also helps set off explosives safely.
Compressed air powers material handling equipment and is even mixed or fluidized with materials like coal for easier handling.
Air compressors are involved in everything from cleaning filters to keeping mining equipment free of dirt and debris. Low-pressure air helps remove inorganic and organic matter from the activated carbon used in the leaching process.
Low-pressure blowers help circulate air through the wastewater from the refining process, allowing the water to be reclaimed and reused. Since most mining operations occur in remote, water-challenged locales, water conservation is critical.
Water treatment facilities in a copper mine and processing plant.
Most mining operations choose one of the three major types of compressors: centrifugal, reciprocating or rotary screw air compressors. Each offers some unique benefits, depending on the application.
Generally, a centrifugal air compressor is most cost-effective for high-volume applications (above 2,500 CFM). A reciprocating compressor is the best choice for low-volume applications (less than 20 CFM). But rotary screw air compressors are the best for everything in between. For more on the subject, read our blog post, “Which Type of Air Compressor Is Best for Your Application?”
Be careful not to oversize your system, especially if you’re using a rotary screw air compressor. It may seem counterintuitive, but with air compressors, “too much” is almost as bad as “not enough.”
Here’s why. Screw compressors are designed for a 100% duty cycle. Run them significantly less than that, and you’ll waste energy, reduce equipment lifetime and perform more maintenance. Similarly, when there’s not enough gas for a centrifugal air compressor to compress, it loses its ability to transfer energy from the shaft to the fluid, causing a dangerous reversal of flow, or surging.
As a result, do not try to size your compressor with “room to grow.” If you need help sizing your system appropriately, contact your local air compressor consultant.
Most rotary screw air compressors use load/no load controls, sometimes called online/offline. With this approach, you set load and unload pressures, such as 115 PSIG and 125 PSIG, respectively.
That gap of 10 PSIG (pounds) is called the pressure band. The goal is to keep your rotary screw air compressors from loading and unloading too fast because starting and stopping too often increases thrust loads, reducing bearing life. That process can exceed the maximum starts per hour on electrical components, specifically the inrush current on the motor. You can conserve energy by setting the header pressure as low as possible.
Compressed air systems lose between 30% and 50% of their volume to air compressor leaks, with poorly maintained systems running as high as 80%.
As a result, one of your first tasks is determining how many leaks you have. And estimating how much you can save by fixing them. (To find out how much you might save with an audit by an air compressor professional, see our blog post, “How an Air Compressor Audit Can Reduce Operating Costs.”)
More than 80% of leaks occur in the compressed air distribution system. What air compressor pros call “the dirty 30”—the last 30 feet before the end-use application. The dirty 30 includes hoses, reels, filters, regulators or lubricators on the piping that connect the air supply to your machinery. Plus, even end-use tools can have internal leaks, especially if they are old or poorly maintained.
The situation is complicated by the fact that 80% of leaks are inaudible. For more on leaks, see our blog post, “How to Find and Stop Air Leaks.”
It’s essential to make sure your compressed air system is properly maintained. Filters are critical. Clogged filters will impede and eventually block airflow, causing energy loss that is both unnecessary and avoidable. As a result, we recommend:
And with dryers, you’ll want to ensure that drains and traps are clear and open.
An air compressor audit (a more detailed evaluation than a distributor’s monthly or quarterly assessment) can produce significant benefits for your organization:
Most companies find an audit pays for itself many times over, as they record annual savings in the tens if not hundreds of thousands of dollars.
The good news is that an audit will require little, if any, interruption in your operation. Once installed, the dataloggers chug away, recording critical parameters in your system and quantifying air flow, pressure drops, humidity, temperature and energy consumption.
For more on the difference between an audit and an assessment, see our post, “When To Do a Compressed Air Audit, When To Do an Assessment.”
Mining companies will benefit from the advice of an air compressor professional when selecting equipment for their demanding applications. From sizing and peripheral equipment to operation and maintenance, a good consultant can help you optimize not only the performance of your system, but also its longevity and lifetime cost. We work with a nationwide network of independent distributors, who can provide the on-site help and guidance you need.
Choosing the right air compressor to support the mining equipment across your operation is critical to your success. If you need help with air compressor selection, operation or maintenance, get in touch with the experts at Kaishan. Contact us today.
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