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Mining for Copper & Zinc

Between 1978 and 1980, an underground exploration campaign was undertaken to provide additional exploration data to supplement previous surface exploration of the Sa’adah and Al Houra deposits. The underground development and exploration activities were undertaken by a North American Mining contractor. A (-) 15% straight decline with dimensions 6.5mW x 4.5mH was driven 700m from a portal located approx.8m above the floor of Wadi Sa’adah at 1620m elevation to provide access to an exploration drift at 1515mL. The exploration drive was excavated along the hanging wall side of the Sa’adah deposit and along the foot wall side of the Al Houra deposit.


The distance between the exploration drift and the respective hanging wall and foot wall was not consistent, and in some areas, the drift is located so close to the contacts that there is doubt as to whether access along the current development can be maintained throughout mine life.

The 5mW x 4.5mH exploration drift was extended 730m North from the decline intersection to 5110mN. Three cross cuts were driven to expose the full width of the Sa’adah deposit and provide additional deeper exploration drilling locations further from the hanging wall and foot wall. Exploration indicated that at 1515L, the Sa’adah mineralization was present along a strike length of approx. 650m between 4500mN and 5180mN.

The 5mW x 4.5mH exploration drift was extended 1280m South from the decline intersection to 3100mN. Two crosscuts were driven to expose the Al Houra mineralization and provide additional exploration drilling locations. At approximately 3600mN the dimensions of the exploration drift to the current face position were reduced to 4mW x 4mH. Exploration indicated that at 1515L the Sa’adah mineralization was present along a strike length of approximately 400m between 3550mN and 3950mN.

Identification of a small gossans on the hillside encouraged exploration drilling from the surface, and a third, high-grade deposit was identified. The Moyeath deposit is located some 700m to the East of the existing exploration development.

MINE ACCESS STRATEGY

Ore will be delivered to a primary crusher located on the surface, 250m from the portal. When mine waste must be transported to surface, the material will be added to a waste dump extending to the South East of the crusher, on the edge of Wadi Sa’adah. Rock movement within the mine is performed by Caterpillar AD30 dump trucks. In the first phase extension of the mine, we developed return ventilation raises from Sa’adah and Al Houra to the surface. Development and production using trackless equipment commenced in Sa’adah and Al Houra deposits. The ventilation raises are equipped with ladder-ways, providing a secondary means of emergency egress from both Sa’adah and Al Houra. A new decline will be driven from the surface to access the Moyeath deposit. The new decline will originate at a new portal located South of the existing portal on the lower slopes of Wadi Sa’adah.


The early production available for mining was from the Sa’adah deposit from 1525mL, close to the existing 1515L. A 4.5mW x 5mH upward ramp extension was provided to access the ore above 1515mL and below the 25m crown pillar with a base at about 1590m elevation. Ore and waste are being dumped into passes leading to the truck loading chutes on 1525mL. A ramp has been completed to the base of the Sa’adah zone at 1300m L.

MINE DEVELOPMENT

A 4.5mW x 5mL ramp has been provided for truck access to developing sites. The dimensions have been reduced to 4mW x 4mH at the entry point, using 4.8m3 scoops while it will be only 3mW x 3mH in the narrow parts of the vein, using 1.9m3 scoops. Ramps are 15% gradient.


Raises are installed with hand-held drills using an alimak raise climber or where possible, with shorter raises between sub-levels, by drop-raising using a long-hole drill. The main return air rises from each mining zone are equipped with a ladder for emergency egress due to the remote surface locations of Al Houra and Sa’adah.

MINING METHODS

AMAK has considered the following mining methods, which will be employed as required:

  • Open-Stope, Longhole Mining
  • Sub-Level Retreat Blast-Hole Stoping
  • Vertical Crater Retreat Blast-hole Stoping

” We completed the testing and commissioning of our mining facility , which is fully operational as of quarter 3 of 2012. The facility was officially inaugurated

by His Royal Highness Prince Mishaal bin Abdullah bin Abdulaziz Al Saud, Prince of Najran on 2 October 2012 “