Atlas Copco Secoroc Raiseboring tested a new carbide grade at Kiruna Mine in the North of Sweden with Bergteamet Raiseboring Group. The harder tougher grade of carbide was used on standard Magnum V cutters and dressed on an 18 cutter, 3.1 meter diameter integral reamer. This reamer employs 5 gage cutters, 3 next to gage cutters with 2 cutters on each of the remaining rows throughout to the center of the head. The total number of cutters on the reamer is 18 (eighteen).
The machine being used was an Indau 500 with 2 million pounds (8900 KN) of thrust and 295,000 Ft-lbs (400 KN-m) of torque. The cutters were loaded from 55,000 to 60,000 lbs (25 to 27 metric tonnes) each throughout the raise. The 1128 ft (344 meter) raise was pulled in massive, hard, abrasive and ductile Syanite with an Unconfined Compressive Strength averaging 350 MPa (50,700 psi) – (ranging from 300 to 420 Mpa or 43,500 to 60,900 psi).
The previous best at 3.1 meter diameter in this type of ground at Kiruna has been noted at about 820 feet (250 meters). This raise employed Sandvik CRH4 and CRH5 cutters on an integral 3.1 meter reamer which employed 4 gage cutters, 4 next to gage cutters and 2 cutters in each of the remaining rows. The total cutter count was 18.