To start, the crew performed a visual inspection to the silo exterior, interior, platforms and other appurtenances to assess the condition of the structure and document any anomalies. Schmidt Hammer readings were also carried out to measure the elastic properties of exterior concrete. The inspection allowed IA to quantify the location and type of material blockage issue and assign the Cardox blasting solution.
Cardox tubes are filled with liquid carbon dioxide, like a fire extinguisher. When energized by the application of a small electrical charge, the chemical heater instantly converts the liquid CO2 into a gas. The conversion expands the CO2 volume and builds up pressure inside the tube until it causes a disc, located at the end of the tube to burst, which releases CO2 through directional discharge nozzles. This creates a powerful force of pressure, up to 40,000 psi, strong enough to safely blast buildup off the walls in closed structures. This process can dislodge more than 3 tons of buildup in milliseconds.
In order to administer Cardox shots, strategic holes were drilled through the silo’s concrete wall to install Cardox ports and place Cardox tubes. Once activated, the Cardox system blasted off loose debris and dislodged congealed soybean meal stuck to the interior walls of the silo. Eventually the team was able to safely enter the silo with rope access and installed more Cardox shots inside the silo, drilled into the hardened buildup material to break it apart. The Cardox method allows blasting work to be performed remotely without directly exposing workers to unsafe conditions. BinWhip pneumatic whipping system was also utilized to scrape and break up the material. Once sufficient progress was made, the team was able to enter the silo again and hand shovel out the remaining debris.