Cementation Americas completes one of the largest North American raise bores

Cementation Americas has announced the completion of the full faced raise bored raise at Solvay Chemicals #5 shaft in Green River, Wyoming. Project requirements were to complete a 6.7-metre diameter shaft, complete with concrete liner, from surface to a depth of 459 metres. Concrete liner thickness increased as the depth of the shaft increased, so the initial concept was to complete a pilot slash raise with a raise bore drill and then slash from the top down to achieve the differing diameters to accommodate concrete liner thickness.

Cementation instead proposed a full face raise bored shaft solution with variable diameters for each section. We worked closely with Sandvik to design, engineer and manufacture a reaming head that could be diminished in diameter rather than manufacturing different diameters of outside wings. Final design allowed for five diameter options; maximum of 8.1 metres, down to 7.5 metres, in increments of approxximately 15 cm. The 8.1-metre diameter reamer consisted of 12 individual sections, 46 cutters and weighed 136,000 lb.

Following completion of 20.7-metre deep collar excavation and lining, Cementation’s Strata 950 raise drill was set up over the collar and a 40-centimetre diameter pilot hole was drilled with Micon’s rotary vertical drilling system (RVDS). When the completed pilot hole was surveyed, the total deviation from vertical was found to be less than 10 cm over entire length of pilot hole.

Based on the pilot hole survey, it was determined that the first leg of the shaft would be reamed to 9-metre diameter for 179.2 metres of shaft, followed by 7.6-metre diameter for the next 86.9 metres of shaft and 7.5-metre diameter for the final 163.1 metres of shaft to surface.

Reaming of the shaft was completed on April 24, 2022, and the Cementation shaft crews are  now in the process of completing the shaft lining. This raise was one of the largest ever pulled in the America’s and was completed without incident. Its success was the result of a collaborative effort by all parties involved by providing the best technical solution for the Solvay Chemicals #5 shaft.

For more information on Cementation, visit www.cementation.com.