Breakthrough Drilling Video
Zereko Mining presents “Breakthrough Drilling”. A combination of knowledge and experience to provide the mining and civil industries with innovative drilling technology. This video highlights the development of a specialized 24″ cased drilling machine for backfill and rock.
The rig and tools were tailor made for the underground environment, drilling through rock and unpredictable backfill to the top of an open stope where there was no access. Conventional methods of drilling had repeatedly failed. We innovated a unique method of drilling a cased hole through the most difficult material.
It was determined that utilization of reverse circulation in the hole hammer and under reamer with the method of inducing the casing down the hole as it drilled would all be necessary to successfully bore through the unpredictable and contrasting material.
Reverse circulation is a very effective way to utilize power and air. Air travels down the outer wall of the dual wall pipe, the cuttings are returned through the centre of all the components to return to the top of the drill.
All of the components were specially designed to accommodate reverse circulation. From bottom to top URG full gauge under reamer 24″ hammer, dual wall reverse circulation drill pipe casing driver and top drive. These tools are fitted on a low profile mast 15′ in height when fully erected.
This unique under reamer is full gauge meaning the 3 collapsible gauge reamers drill 360 degrees around the hole rather than an eccentric design. The 3 wings cam out 25″ in diameter on forward rotation and retreat at 23″ on reverse rotation.
Pressurized air exhausts on the outer face of the bit and across to the return discharge at the centre of the bit. It is designed to keep mechanical parts clean and to keep a smooth flow of air. This bit powered by an ITH can drill through a variety of materials. It can effectively drill through the hardest rock or the softest backfill.
The hammer is 24″ reverse circulation, it is low profile accommodating a torus shaped piston. Besides the piston there are no moving parts making a the system very dependable as well as powerful.
This system can drill through a variety of materials provided you maintain the integrity of the hole. This is done by pushing the casing closely behind the bit.
The drill pipe and casing are loaded together, therefore casing is cut at the same length as the drill string(4′ 6″) making the process possible.
Rather than pulling the casing from the bottom with the shoe and the in hole hammer, we drive it from the top using a casing driver. We found this was the most reliable as well as the least complicated process.
The low profile driver accommodates the 1000 lbs piston pushing the anvil seated on the top lip of the casing. It is fastened to the top drive with a pair of hydraulic cylinders. This allows the operator flexibility to synchronize the bottom of the casing to the gauge reamers on the bit.