Latest mine winding contract for Sheffield engineers
Sheffield engineering skills will be helping to recover Canadian nickel and copper ore, at one of the largest mining and refining operations on earth.
A 16.5 foot diameter double drum hoist, part of a $12.7millionCDN mechanical, hydraulic and electrical drive package, is being manufactured at DavyMarkham’s Prince of Wales Road works to international quality and safety standards, involving regular audits and inspection of workmanship.
The customer is CVRD Inco, one of the top three diversified mining companies in the world, and the installation is for the reopening of its Totten #2 shaft at Sudbury, Ontario, 350km north of Toronto, where extreme winter temperatures rarely exceed –20ºC. The CVRD Inco turnkey project involves the design, manufacture, installation and commissioning of a double drum winch for hoisting around 2600 tonnes per day, operating two daily 10.5hr shifts, 354 days per year, and includes an electrical drive system with 3.5MW synchronous AC motor, subcontracted to ABB Canada. Final commissioning is scheduled for late summer 2008.
Acquired last year by Brazil-based CVRD, itself a global leader in iron ore production, the Canadian Inco company has operated for over 100 years in Sudbury, known as the nickel capital of the world, and has recently invested over $19 million annually on exploration in the area. The latest and most talked about of Inco’s projects is at Totten, where it announced plans to invest $400 million in starting up production again, its first new mining operation in Sudbury for over 35 years. The No 2 shaft was originally operated on a restricted basis in the 1960’s, then was subsequently closed and flooded, but strategic studies have now prompted its reopening, with an expected life span of 20 years.
CVRD Inco now proposes to dewater the existing shaft, replace the current headframe with a new 135ft unit, and install a new production service hoist, being built by DavyMarkham, then deepen the shaft. The hoisting plant will have the capacity to haul around 2,200 tonnes of ore and 400 tonnes of rock waste daily, from the 4,110ft level; although to cover the future possibility of removing deposits below that depth, it will be designed to accommodate hoisting from 6,110ft, or almost 1¼ miles below ground.
The production/service double drum hoist and associated mechanical, electrical, automation and control components, being supplied by DavyMarkham, will be capable of serving all duties, including shaft dewatering and deepening. Initially it will operate in single line mode for hoisting a skip-over-cage arrangement carrying men, equipment and material, with a maximum payload of 22,000lbs.
For normal and future duties, it will operate in double drum mode, carrying a production skip on one 21/16” diameter steel rope and a skip-over-cage on the other, with a maximum payload of 36,000lbs. In single drum operation, it will also hoist empty mine conveyances or cages, for level changing purposes.
The basic hoist configuration will consist of one fixed and one clutched drum assembly, running on a two-piece, three-bearing drumshaft, which will be directly coupled to a synchronous AC electric motor drive, with the clutched drum nearest the motor and the fixed one farthest from the drive. Each featuring an 18.5ft diameter flange, the two drum assemblies will be manufactured in halves from 2.75” thick rolled steel plate, then bolted together, with the 16.5ft diameter. 6” thick drum shell precision machined to provide parallel grooving and half-pitch crossovers, to accommodate the 21/16” diameter flattened-strand ropes.
The 32ft long, machined forged-steel drumshaft assembly will be manufactured in two sections, together weighing over 40 tonnes; these will be bolted together on site, using high tensile fasteners, in order to reduce the maximum lift weight of individual components, in line with hoisthouse craneage. It will run on three anti-friction bearing assemblies, with a service life of >300,000 hours, which will incorporate monitoring sensors linked to the hoist PLC.
The brake and clutch operating system will comprise a series of hydraulic circuit modules, interconnected to form a four-channel arrangement and powered by a 175 bar hydraulic power unit. The brakes are spring applied, hydraulically-released Svendborg disc units, providing a minimum static holding torque of 1,795 kNm at each drum, while the clutch mechanism will be a multi-tooth sliding type.
Powering the double drum winder is an AC mine hoist drive system, subcontracted to power and automation technology specialist, ABB Inc of Montreal, Quebec. This will comprise ABB’s ACS 6000 SD direct torque control unit, together with an AMZ2000 type synchronous motor, with outputs up to 3.5MW and a rated torque of 800kNm. Offering a relatively small footprint, 98 per cent efficiency and superior control performance, the ACS drive system features an active rectifier unit for 4-quadrant operation and reduced energy consumption. A digital hoist control system will also be supplied, complete with graphical PC-based HMI for operation and monitoring of the mine hoist parameters and comprehensive management reporting.
DavyMarkham will be responsible for installing and commissioning the mine hoist system, managing all the mechanical and electrical work on site, then scheduling final inspection and testing of the equipment prior to rope-up by the nominated shaft sinking contractor. It will also provide classroom instructions and hand-on training to local crew, for future operation and maintenance of the system.
