The UK engineering company, DavyMarkham, has been awarded a $20 million order for the supply of mining hoists and associated electrical drives and controls by gold producer IAMGOLD of Toronto, Canada. The contract includes a large double drum hoist with a diameter of 6.4 m, a drum width of 2.4 m and a payload capacity of 20,000 kg. It will serve as the main production hoist, operating at depths down to 2,652 m, at IAMGOLD's new Westwood exploration programme in Canada.

IAMGOLD said in January that Westwood has the potential to produce 200,000 ounces of gold per year at a cash cost of $290 per ounce and that capex to bring a mone into production were estimated at $329 million. Over a projected mine life of 15 years, Westwood is estiomated to produce an average of 187,000 ounces of gold per year at an average cash cost of $298 per ounce, generating a pretax operating cash flow of $665 million.

This is a very important contract gain for DavyMarkham and it is testimony to the cutting-edge design engineering technology we are applying to this key market sector and the extreme precision of our heavy engineering, says Managing Director, Kevin Parkin. IAMGOLD is a major new customer for us and we are delighted to have won this major order in international competitive tender.

Over recent years DavyMarkham has been developing mine winder technology, making inroads into the Canadian minerals market, supplying, according to the company, more than a dozen new hoists for gold and nickel mining projects; it was also the first supplier to the North American market to comply with the South African SABS codes of practice, for deep shaft exploration. The company has worked closely with ABB Montreal on the provision of electrical plant for these projects and gained a thorough understanding of how its drive and control systems operate, ensuring the highest levels of safety, reliability and performance for mine hoisting installations.

For the Westwood project, DavyMarkham will design, manufacture and supply a 6.4 m diameter production hoist and a 5.5 m double drum service hoist, together with associated clutch assemblies and multi-channel hydraulic brake control system. ABB has been sub-contracted to provide drive systems for both hoists, including high voltage motors, industrial drive units, digital hoist control system and a hoist operator station. Delivery is scheduled for late spring, early summer 2010, presently on a supply to mine site basis, although there may be the option of providing installation and commissioning services at a later stage.

Located two kilometres from the company's existing Doyon mine operation in northern Quebec, IAMGOLD's Westwood advanced exploration project began in 2004 to identify potential new deposits. A raise boring machine is already excavating an initial shaft and, once this is complete, the sinking of the main 5.5 m diameter exploration shaft will begin.

This accelerated exploration program puts pressure on DavyMarkham to meet an extremely tight contract deadline, although work is currently progressing to schedule. The principal components were first subject to a rigorous engineering analysis process to predict stress levels and deflections at all critical points in the hoist, with the drums themselves modelled using finite element studies, which accurately represent the thickness of materials to be used throughout the structure. This process enabled the company to recommend a smaller 5.5 m diameter service hoist with geared drive, as the optimum size commensurate with duties, rather than the more expensive 5.79 m diameter, direct drive configuration originally specified.

A particular feature of the DavyMarkham mine hoist design is the provision of a multi-channel hydraulic brake control system, which ensures full SABS compliance and maximum safety under fault conditions. This system has been specified on both IAMGOLD hoists and will be interfaced with ABB's digital hoist control equipment, so that if a fault occurs with one brake channel, only one cluster of brake units is affected and the remaining clusters provide correct brake application and controlled deceleration.

On the drives side, ABB will be supplying a water-cooled ACS6000 series multidrive coupled to a 6,800 kW AC synchronous motor for the main production hoist, with an ACS800 multidrive and two 1,205 kW cast iron induction motors for the service hoist. It will also provide its well-proven digital hoist control and safety supervisory system, to monitor the hoist operating speed envelope and ensure reliable and accurate control of brake systems and other hoist subsystems. This will be linked to a Type PA1 hoist operator control station and Hoistlogger monitoring system, for a simple and clear means of mine hoist operation when full production starts in 2012.

John Chadwick is editor/proprietor of International Mining magazine