Facing the Drilling and Blasting Difficulties at Helwan Quarry, Egypt.

Helwan limestone quarry is located at a distance of 35 km (21.7 miles) to the south of Cairo downtown. Drilling and blasting operations are used to extract the limestone for the Helwan Cement Company (HCC). In 1980’s a new urban community was constructed adjacent to the quarry. This situation led to shifting of the old quarry 5.0 km (3.1 miles) to its current location, to avoid causing blasting problems to the new community. Unfortunately, the new quarry is opened in a highly faulted area, with weak zones of brittle materials. The drilling and blasting crew is facing many difficulties due to the geological complexity along these zones. Moreover, the extension of this community towards the new quarry makes the control of ground vibrations is very important. The above mentioned conditions drive us to apply a series of systematic procedures, to ensure consistent drilling efficiency. These procedures consist of assessment of the optimum type of drilling machine, assurance of drilling parameters by measuring both effective burden along the quarry face, and blast-hole deviation. Sometimes, casing of blast-holes is necessary to be applied. Furthermore, both of ground vibrations (PPV), and velocity of detonation (VOD) were recorded, and most of blasts were thoroughly filmed, using a high speed digital video camera, to audit the applied procedures. The results of this study were used to minimize the drilling difficulties within the faulted areas, improve the safety level of blasting works, and optimize the blasting results through all subsequent quarry operations. Then an adopted technique has been recommended for the future drilling and blasting activities at HCC quarry.