In an order worth around £700,000, the hoist is to be built incorporating reusable components, such as drum sides and disc brake frames, salvaged from a Markham double drum unit originally supplied in 1996.
This follows a competitive tender call issued by Agnico-Eagle Mines, one of North America’s leading mineral exploration companies, with more than 30 years experience of gold production, mainly through underground operations.
The hoist will be deployed for shaft sinking, then production duties on the LaRonde II project, the 3,300m (two miles) deep extension to the current LaRonde operation, based around 650km northwest of Montreal.
The complex machining and fabrication work necessitates matching these existing parts precisely with newly-manufactured mechanical components, such as the drum shell plates, shaft, water-cooled gearbox and clutch operating system.
Recycling and reutilising existing parts leads to significant savings over the price of a new double-drum hoist, which can cost as much as Can$2 million, especially as NDT (non-destructive testing) methods are applied to verify freedom from service-induced structural defects.
Agnico-Eagle’s flagship LaRonde operation, which includes underground mining, a mill complex, treatment plant and secondary crusher building, has produced more than 2.9 million ounces of gold since 1988 and currently uses the 2,250m deep Penna Shaft, the deepest single-lift shaft in the western hemisphere.
The LaRonde II project involves a deeper ore reserve containing an estimated 3.6 million ounces of gold, inaccessible by the existing Penna Shaft, which requires sinking an internal shaft or ‘winze’ to a depth of around 2,900m below ground. A series of ramps will then enable mining down to approximately 3,300m.
The hoist will be used initially to sink the new winze, before being converted to a production-only winch carrying 17t skips, and is being manufactured by DavyMarkham to meet health and safety criteria for both duties. With a line pulling rate of 87,000lbs, it consists of two drums on a single shaft, one fixed and the other clutched, which means they can work independently, one drum being disengaged via the clutch for loading, while the other is raised to the surface for emptying.
The hoist will actually be installed deep underground at a depth of 2,060m, enabling Agnico-Eagle to sink a shaft a further 810m, then ultimately mine to a depth of 3,300m below ground. For the initial duty, the total cycle time for each drum will be 125 seconds, including loading, raising and emptying, and, for the final stage, 171 seconds, the hoist typically working 10 hours per day.
The reused components of the hoist itself have an interesting engineering history that links back to Britain’s coal mining industry. In 1996, DavyMarkham acquired a used hoist from Frickley Colliery in Yorkshire for Agnico-Eagle, designing and fabricating two new 16ft diameter drums to fit the existing shaft, bearings and bedplates. In 1999, it upgraded the same unit for skip hoisting duties down to 2,250m in the Penna Shaft, supplying new 19ft drums, a new shaft, clutch mechanism and disc brake system.
Installation underground is expected to commence in May, with commissioning completed by the end of July 2007.
The hoist is to be built incorporating reusable components, such as drum sides and disc brake frames, salvaged from a Markham double drum unit originally supplied in 1996 wire rope drum
