Can you dig it?

23 December 2020

The mining industry relies on highly-specialised lifting equipment for maximum efficiency and minimal downtime. Daniel Searle spoke to some of the leading manufacturers in the sector.

When it comes to providing lifting equipment for the mining sector, one size does not fit all.

Johannesburg, South Africa-based Condra Cranes produces ranges of cranes and hoists suitable for all types of mining exploration and production, the company explains, tailored to the type of ore and specific operating environment of the individual customer.

The company runs two factories in South Africa and one in each of Bulgaria and Chile, alongside a worldwide network of service agents to support all of its installations. Its full product portfolio includes single- and double-girder overhead cranes, portal cranes, bridge cranes, cantilever cranes and hoists, as well as end carriages, crabs, bottom-blocks, cable-loop systems and other crane components.

The company highlights a couple of flagship projects: a 47m-lift, 150t overhead maintenance crane at Sishen’s primary crusher plant, which is one of several Condra machines at that South African mine, and its pre-sink portal crane at Oyu Tolgoi in Mongolia.

The pre-sink portal crane reduces by up to 75% the time needed for the pre-sink phase of mine development, explains Condra. It’s a very different type of crane to the level-luffing type of crane traditionally used for pre-sinking, instead using a high-speed, high-lift main hoist to remove excavated spoil vertical by kibble, through an opening in the centre of a drilling stage, positioned by two separate stage-winders mounted on the same portal frame. Lift speed is a metre per second—15 times faster than the four metres per minute found in standard mine workshop applications, says Condra.

More recently, the company also installed a fully-automated grabbing crane at a platinum mine in South Africa. It follows a series of semi-automated systems installed since 2003, all of increasing sophistication. The fully-automated system, which was delivered at the beginning of 2020, is a grabbing machine with dual hoists, variable-speed drives throughout, and four long-travel motors to provide remote crane positioning accurate to within 5mm. The crane is programmed from a remotely-located control room, with onscreen monitoring provided via closed circuit television.

Spreading The Net

Any sector can be liable to experience fluctuations in prosperity and demand: as well as mining, Condra targets heavy industry, general manufacturing and the energy sector, so that should demand in one area decline, it is compensated for with continuing sales in the other three.

And, within the mining sector, the company further spreads its interests by actively selling into mines associated with different minerals, Condra explains.

The company also offers refurbishment services, including the refurbishment of competitors’ cranes: in markets such as South Africa that are geographically distant from northern-hemisphere manufacturers, says Condra, the availability of local crane refurbishment can often mean that an end user avoids a long delay.

The company’s refurbishment division targets cranes that have been operating for between 15 and 30 years, at which time a mine will often consider the options of either replacing or refurbishing the crane, depending on maintenance policy and the workload of the crane. Condra provides a consulting service to advise on the best options, covering a range of solutions with varying productivity gains and costs. The refurbishing services often also includes a technical upgrade.

Commenting on the effects of the Covid pandemic on business, Condra’s managing director Marc Kleiner said that there has been a noticeable increase in the postponement of delivery dates for confirmed orders, due to the difficulties of mining under pandemic conditions. The company has factored the delays caused the pandemic into the next two years of the company’s medium-term planning.

High-Tech In The Right Areas

At Italy-based Misia, around 90% of the company’s production is the standard versions of its XM series of wire rope hoists. The remaining 10% of production is dedicated to special applications and revamping, says Misia, which highlights the flexibility of the company’s product offerings and its ability to adapt to a range of industrial applications such as the mining sector.

Misia has always been appreciated in the mining sector for the reliability, high-level performance and long life-spans of its lifting equipment, says the company. Its market acceptance is now better than ever, for an interesting reason: the company’s competitors are continuing to use higher technology components in their products.

These include smaller high-tensile wire ropes, smaller-diameter drums, lowerkilowatt motors, and smaller brakes.

However, high-tech components offer no long-term advantage, says Misia, and are more expensive to service and maintain. That’s a view shared by Gerry McLernon, director at Australia-based SPT, which sells Misia cranes. The mining sector represents SPT’s biggest market, accounting for around 70% of its customer base.

“We first sold Misia in Australia in 1996 and the market acceptance is better now than ever, this is because our competitors continue to change models to higher technical components,” says McLernon.

There are other reasons too for the popularity of Misia’s products in the Australian market, adds McLernon: “Customers prefer Misia because the hoist is manufactured as a heavy-duty industrial product. “All hoists and cranes must comply with Australian standard AS1418 and Worksafe Australia Government Regulations. Misia complies with these requirements.” Through its distributors, Misia supplies equipment to mines all over the world. The mining sector needs specialists and the company has found a number of suitable partners, including SPT, says Misia. “To deal with a specialist like SPT means to supply hundreds of hoists chosen directly by the customer and installed as lifting equipment without really having ever had any issues,” adds Misia.

The company adds that through its options of conical or cylindrical asynchronous electric motor, both with single and double speeds, it offers a choice of products that can meet all the requirements of its customers.

Brake Time

For personnel cages, FLSmidth has recently launched its Cage Guardian Safety Brake for steel guides, which uses mechanical systems to enhance safety of underground mine workers in the event of slack-rope or a rope break.

The brake uses steel guides rather than conventional timber guides, which eliminates the inherent uncertainties of wood, says FLSmidth, and provides an enhanced degree of safety, repeatability and reliability. Timber guides can be subject to moisture and defects, adds the manufacturer, while steel guides provide stable properties and dimensions and are easier to maintain.

The brake is also purely mechanical, with no hydraulics, pneumatics or electricity, to provide fail-safe operation even in wet or contaminated guides. The actuation and operation are performed by redundant mechanical systems, which only require a slack-rope or rope break to bring the cage to a safe stop. Average deceleration rates of 0.9g–2g (9–20m/s/s) provide a low jerk rate.

The cage can be easily retrieved after the brake is used: the Cage Guardian inflicts minimal damage on the cage and guide components, says FLSmidth, resulting in faster redeployment of the cage. Timber guides, by comparison, need to be replaced after a safety catch event, adds the company.

Each brake system is factory-tested and calibrated for the mine-specific applications. The systems are also free-fall tested, with results documented with a certified test certificate.

A customised Condra pre-sink portal crane in Mongolia
SPT first sold Misia hoists in Australia in 1996
Misia supplies lifting equipment to the mining sector in Australia through distributor SPT
Condra’s pre-sink portal crane in Mongolia in more detail