In underground mining, steel casing or steel pipe is used to line holes that have been bored or drilled for rising mains water, utility lines and paste fill, protecting the contents from damage and loss into open voids or broken ground.
The installation of steel casing using conventional welded methods can be time consuming and costly for underground mining projects. Depending on the requirements, it can take days to install and necessitates additional labour and equipment hire such as boilermakers, chairing frames, cranes or Integrated Tool Carriers.
Following a rigorous development process, PYBAR Mining Services is now offering an improved solution.
PYBAR COO Brendan Rouse said, “Our specialist drilling division recently received a tender for ITH drilling and installation of steel casing for paste fill application.
“With the company’s core values of ‘Safety, Service, Respect and Results’ front of mind, the team identified an opportunity to streamline the drilling and installation process by using one drill to conduct the drilling, reaming and casing operations while also improving safety, efficiency and reducing delays associated with cranage, suspended loads and hot work in an underground environment.”
In collaboration with steel casing manufacturers and engineers, a threaded casing installation system, which is far more productive than traditional welded methods, was designed. The method not only cuts project timeframes but also reduces the manual handling and logistical issues encountered with the welded method, particularly in long shallow dipping holes.
The ability to lift, rotate and lower the casing mitigates some of the risk associated with the casing hanging up or becoming stuck part way down the bore hole – common issues often encountered when installing steel casing.
Eliminating hot work and the associated management controls from the underground environment, the threaded casing system features specially designed joints comprising external couplings with machined tool joints, specialised installation tooling and casing hanger. The casing has been engineered to exacting specifications and ensures a consistent pressure rating is maintained throughout the length of the installation.
The method results in flush internal joints, greatly increasing life expectancy over the butt welded casing method by reducing wear points for erosion of the casing. For life of mine applications, ceramic coating is also available to further increase the casing life. In addition to paste fill, casing can be manufactured to suit a variety of applications including service holes and rising mains applications.
The Cubex Aries ITH drill, a recent addition to PYBAR’s Drilling Division, was designated as the ideal drill for installing the system. While raise bore rigs have previously been used to install steel casing, the highly flexible Aries ITH offers a far greater range of angles where casing can be installed over raise bore or conventional welded methods. Costs can be further reduced with longer lengths of casing and compared to the raise bore installation there is no requirement for cement pads.