Post by melody on Oct 22, 2013 21:03:57 GMT -5
Joint Legislative Conservation Committee
10/21/13, 12:00 p.m., Room G-50, Irvis Office Building
By Mike Howells, PLS
The committee received a briefing on Trompe technology and its applications in acid mine drainage and other systems.
Bruce Leavitt, a professional mining hydrogeologist, speaking along with Tim Danehy, from BioMost Inc., offered a history of trompe systems, which use water pressure to compress gas. In the case of flooded mines, water pressurizes air which is used to aerate the mine water, thereby raising its pH.
Leavitt first detailed the history of passage systems in Pennsylvania, funded through the Good Samaritan Act, Growing Greener, and Act 13. He said despite such efforts, 5,596 miles of streams remain impacted by acid mine drainage. He highlighted mines around the Pittsburgh region and the number that are discharging into nearby waterways. He said waters that are alkaline or circumneutral can be treated passively, even when there are large discharges.
Leavitt explained in more detail how trompe systems are used to treat acidic mine water. Using a vertical pipe, he said, high velocity water falling through the pipe carries the air down along with it to an air separation chamber, where the air is collected for use and the water passes through and discharged.
The trompe itself is not a treatment but an air compressor, he explained, with flow dependent on pipe diameter and maximum air pressure dependent on the length of the return pipe - typically 13 feet in acid mine drainage applications. Depending on requirements, they can be constructed in parallel or series, multiplying the amount of air generated by the same water.
Developed in the 1600s in Italy, Leavitt said the technology was embraced by the Spanish and was integral in the Catalan Forge, where it replaced the use of bellows and brought fame to “Catalan steel.” Brought to America, the Spanish constructed forges utilizing the design in California. Leavitt said the principle was “rediscovered” after a period by Canadian Charles Taylor, who built massive trompes, the largest of which went down 345 feet and delivered 128 psi to area silver mines near Cobalt, Ontario, where it was used to operate rock drills and ventilate the mines.
Leavitt explained the process by which mine water is treated. He said ventilation is needed in several cases: when ferrous iron is present, and air can turn it to ferric iron; when raw water has a low dissolved oxygen content; and when it has elevated carbon dioxide. Aeration removes CO2 and increases pH. The higher the pH, he said, the faster iron is oxidized, shortening the need for long retention times.
Leavitt reported the technology works not only for bituminous but also anthracite mine sites, though it will not affect manganese levels.
Detailing the costs of trompe systems, Leavitt said smaller systems can use PVC bought from Home Depot or Lowes. Larger systems require tubing purchased from specialist stores. A 20 to 100 gallon per minute (GPM) system costs around $12,400, while a 500 to 300 GPM flow rate system nears $50,000. Comparable traditional systems, he said, require ongoing electricity and maintenance costs while trompe systems will not. Danehy added it is the only option for places where electricity is not available or affordable.
Leavitt said there are four systems in place at three sites, with another system being installed in several weeks. He reported a number of grant applications are in place awaiting approval.
Shifting to semi-active lime dissolution treatment, Leavitt described waterwheel-powered lime dosers, which react with carbon dioxide to form calcite. He explained Danehy’s “MixWell” concept, in which raw water is fed to the bottom of the MixWell chamber, where lime or lime slurry is added and agitated by raw water and disintegrates into smaller particles, defeating the problem of buildup on the waterwheels. Leavitt explained how by incorporating a trompe, circulation keeps lime particles moving while they dissolve further. He said this translates into a 40-percent reduction in the cost of lime at a given site.
Leavitt noted that beyond mind drainage, trompe systems could be applied to sewage treatment, aquaculture, lake aeration, and chemical mixing.
10/21/13, 12:00 p.m., Room G-50, Irvis Office Building
By Mike Howells, PLS
The committee received a briefing on Trompe technology and its applications in acid mine drainage and other systems.
Bruce Leavitt, a professional mining hydrogeologist, speaking along with Tim Danehy, from BioMost Inc., offered a history of trompe systems, which use water pressure to compress gas. In the case of flooded mines, water pressurizes air which is used to aerate the mine water, thereby raising its pH.
Leavitt first detailed the history of passage systems in Pennsylvania, funded through the Good Samaritan Act, Growing Greener, and Act 13. He said despite such efforts, 5,596 miles of streams remain impacted by acid mine drainage. He highlighted mines around the Pittsburgh region and the number that are discharging into nearby waterways. He said waters that are alkaline or circumneutral can be treated passively, even when there are large discharges.
Leavitt explained in more detail how trompe systems are used to treat acidic mine water. Using a vertical pipe, he said, high velocity water falling through the pipe carries the air down along with it to an air separation chamber, where the air is collected for use and the water passes through and discharged.
The trompe itself is not a treatment but an air compressor, he explained, with flow dependent on pipe diameter and maximum air pressure dependent on the length of the return pipe - typically 13 feet in acid mine drainage applications. Depending on requirements, they can be constructed in parallel or series, multiplying the amount of air generated by the same water.
Developed in the 1600s in Italy, Leavitt said the technology was embraced by the Spanish and was integral in the Catalan Forge, where it replaced the use of bellows and brought fame to “Catalan steel.” Brought to America, the Spanish constructed forges utilizing the design in California. Leavitt said the principle was “rediscovered” after a period by Canadian Charles Taylor, who built massive trompes, the largest of which went down 345 feet and delivered 128 psi to area silver mines near Cobalt, Ontario, where it was used to operate rock drills and ventilate the mines.
Leavitt explained the process by which mine water is treated. He said ventilation is needed in several cases: when ferrous iron is present, and air can turn it to ferric iron; when raw water has a low dissolved oxygen content; and when it has elevated carbon dioxide. Aeration removes CO2 and increases pH. The higher the pH, he said, the faster iron is oxidized, shortening the need for long retention times.
Leavitt reported the technology works not only for bituminous but also anthracite mine sites, though it will not affect manganese levels.
Detailing the costs of trompe systems, Leavitt said smaller systems can use PVC bought from Home Depot or Lowes. Larger systems require tubing purchased from specialist stores. A 20 to 100 gallon per minute (GPM) system costs around $12,400, while a 500 to 300 GPM flow rate system nears $50,000. Comparable traditional systems, he said, require ongoing electricity and maintenance costs while trompe systems will not. Danehy added it is the only option for places where electricity is not available or affordable.
Leavitt said there are four systems in place at three sites, with another system being installed in several weeks. He reported a number of grant applications are in place awaiting approval.
Shifting to semi-active lime dissolution treatment, Leavitt described waterwheel-powered lime dosers, which react with carbon dioxide to form calcite. He explained Danehy’s “MixWell” concept, in which raw water is fed to the bottom of the MixWell chamber, where lime or lime slurry is added and agitated by raw water and disintegrates into smaller particles, defeating the problem of buildup on the waterwheels. Leavitt explained how by incorporating a trompe, circulation keeps lime particles moving while they dissolve further. He said this translates into a 40-percent reduction in the cost of lime at a given site.
Leavitt noted that beyond mind drainage, trompe systems could be applied to sewage treatment, aquaculture, lake aeration, and chemical mixing.