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Strengthening an Existing 20-PSI Mine Seal with PPG's Polyurea Coated Retrofit.

PB2013101136

Publication Date	2008
Personal Author	Millero, E. R.
Page Count	147
Abstract	Analysis and testing have been completed for utilization of polyurea coating in a mine seal application to improve blast effectiveness of the mine seal. The MICON 550 seal was selected for analysis and testing for the polyurea coated modification. The baseline seal used two walls of dry stacked solid concrete blocks separated by a 16 inch thick polyurethane core. The unmodified seal was an approved 20 psi mine seal. The program goal was to increase the mine seal blast pressure sustainability of a baseline 20 psi seal to greater than 60 psi. A coated retrofit design was developed for the Micon 550 seal which includes a secondary 8 inch thick polyurethane core, secondary block wall, and .125 inch thick polyurea coating. The retrofit configuration was installed and tested at the Lake Lynn Experimental Mine, and survived a blast test with a peak blast pressure of 78.5 psi with permanent displacement of one inch. A second test was conducted after reinforcement was added by bolting heavy steel angle to the floor on the outby side of the retrofit; the modified retrofit survived a second blast test with a peak blast pressure of 84.4 psi with total permanent displacement of 3 inches. An alternative seal design was also analyzed with and without polyurea coating. A solid concrete block seal was selected for analysis. The uncoated seal was rated at 50 psi, and was predicted by the models to fail at 70 psi peak blast pressure. The coated seal was predicted to survive a minimum 90 psi blast using conservative predictions of potential coating failure. The completed analyses and testing have shown that the PPG polyurea coating can be used to improve the blast protection of mine seal structures.
Keywords	Coal mines Underground mining Mine safety Sealing Polyurea coatings Air infiltration Analytical processes Explosions Mine bursts Mine ventilation Mining industry Retrofitting Mine seals
Source Agency	National Institute for Occupational Safety and Health
Corporate Authors	PPG Industries Coatings Innovation Center, Allison Park, PA; National Inst. for Occupational Safety and Health, Pittsburgh, PA.
Supplemental Notes	Sponsored by National Inst. for Occupational Safety and Health, Pittsburgh, PA.
Document Type	Technical Report
Title Note	Final rept.
NTIS Issue Number	201301
Contract Number	200-2007-20426

Strengthening an Existing 20-PSI Mine Seal with PPG's Polyurea Coated Retrofit.

Strengthening an Existing 20-PSI Mine Seal with PPG's Polyurea Coated Retrofit.
PB2013101136

Publication Date	2008
Personal Author	Millero, E. R.
Page Count	147
Abstract	Analysis and testing have been completed for utilization of polyurea coating in a mine seal application to improve blast effectiveness of the mine seal. The MICON 550 seal was selected for analysis and testing for the polyurea coated modification. The baseline seal used two walls of dry stacked solid concrete blocks separated by a 16 inch thick polyurethane core. The unmodified seal was an approved 20 psi mine seal. The program goal was to increase the mine seal blast pressure sustainability of a baseline 20 psi seal to greater than 60 psi. A coated retrofit design was developed for the Micon 550 seal which includes a secondary 8 inch thick polyurethane core, secondary block wall, and .125 inch thick polyurea coating. The retrofit configuration was installed and tested at the Lake Lynn Experimental Mine, and survived a blast test with a peak blast pressure of 78.5 psi with permanent displacement of one inch. A second test was conducted after reinforcement was added by bolting heavy steel angle to the floor on the outby side of the retrofit; the modified retrofit survived a second blast test with a peak blast pressure of 84.4 psi with total permanent displacement of 3 inches. An alternative seal design was also analyzed with and without polyurea coating. A solid concrete block seal was selected for analysis. The uncoated seal was rated at 50 psi, and was predicted by the models to fail at 70 psi peak blast pressure. The coated seal was predicted to survive a minimum 90 psi blast using conservative predictions of potential coating failure. The completed analyses and testing have shown that the PPG polyurea coating can be used to improve the blast protection of mine seal structures.
Keywords	Coal mines Underground mining Mine safety Sealing Polyurea coatings Air infiltration Analytical processes Explosions Mine bursts Mine ventilation Mining industry Retrofitting Mine seals
Source Agency	National Institute for Occupational Safety and Health
Corporate Authors	PPG Industries Coatings Innovation Center, Allison Park, PA; National Inst. for Occupational Safety and Health, Pittsburgh, PA.
Supplemental Notes	Sponsored by National Inst. for Occupational Safety and Health, Pittsburgh, PA.
Document Type	Technical Report
Title Note	Final rept.
NTIS Issue Number	201301
Contract Number	200-2007-20426