A new, low sulfur coal mine was to be constructed. The main objective of the project was to use Cellular Concrete (Lightweight Grout) to fill the annular space between the Q-Decking, the Mine walls, and the ceiling.
MMSHA (Mine Safety) required the grout to have a minimum psi of 400. In addition, the mining company required the grout to weigh no more than 1400 pounds per cubic yard. The mine was also located in a very remote area.
The mine company planned to have 10 sections of the mine, with each section being approximately 250 feet in length, for a total slope length of 2500 feet. Helitech was to fill each section a quickly as possible to enable the slope to be continued as Helitech did its pumping.
The first section of the mine was filled from the brow (or the face of the mine). In order for Helitech to fill this section, the Cellular Grout had to be pumped over 1000 feet. For the rest of the sections, the Cellular Grout was pumped from the surface through a 10 inch diameter casing down to the slope and into the Q-Decking. As the slope went into the final depth Helitech had to pump the Cellular Grout 750 feet straight down into the final section.
There was one very challenging section to the mine approximately 750 feet into the slope where a cave-in occurred, where ten miners were trapped in the mine. Luckily, no one was hurt and the men were removed from the mine in less than 3 hours.
The challenging aspect was the mining company had to get this particular area secured and grouted as fast as possible before MMSHA would allow them to continue down the slope. The total cave in area was approximately 20 feet high by 70 feet in length.
The cave in was secured in just 3 days. Helitech jumped through many hoops to be out there in 3 days and worked two (2) 24-hour shifts to secure the mine so work could continue. The mining company was extremely pleased and MMSHA approved the cave- in filling job.
The project was completed in 12 sections. Each section took between 3 to 4 days. Helitech performed well and had no issues in completing this project. The mining company was pleased with Helitech’s performance and in meeting critical time paths.