Tag Archives: Mpumalanga

Mentis Africa helps prepare mine rescue drill for action

Mentis Africa is helping prepare South Africa’s Chamber of Mines for potential industry accidents by supplying positive-grip, pressed-section planks and walkways from its Die-Line range for the chamber’s rescue drilling unit based at Colliery Training College (CTC) at eMalahleni in Mpumalanga.

The walkway’s non-slip features, combined with its high strength to weight ratio, made it ideal for the vehicle-mounted drilling unit, according to Rene Lombard, External Sales Representative at Mentis Africa. The walkways and planks have been installed all around the drill vehicle to facilitate easy movement of personnel.

“Its positive serration ensures good traction even in muddy and wet conditions, enhancing the safety and efficiency of people working on the drill during a mine rescue mission,” Lombard said. “Significantly, Mentis Die-Line walkways are lightweight so, while being very strong, adds little extra weight to the vehicle.”

The rescue drill is on 24-hour standby to be deployed, with the assistance of CTC staff, in the case of mine accidents. It can drill a 150 mm diameter hole into the underground area where an accident has occurred, allowing the area to be assessed by camera, and for food and water to be supplied.

It is also capable of drilling a hole of 635 mm in diameter, down which a capsule is lowered to bring trapped mineworkers to surface.

“The Mentis Die-Line products are simple to install, requiring no specialised tools and minimal welding or clipping to supports,” Lombard says. “All the necessary bolts, nuts, washers, fishplates, jointing channels, saddle clamps, splice plates and mesh clips are provided.”

Lombard noted that the Mentis Die-Line walkway sections – plants with 2 mm thickness and walkways sections with a 2.5 mm thickness – can be provided in either 500 mm or 750 mm widths at a standard length of 2.4 m.

“Where the walkway or panel is subject to a corrosive environment – like harsh chemicals or saltwater – the mild steel construction can be bitumen-dipped or galvanised,” she says. “This allows these versatile products to be used in a wide variety of applications.”

Condra to show off crane building abilities on South Africa coal mine dragline contract

Condra is to manufacture a “technically complex crane” to service a dragline at a coal mine in Mpumalanga, South Africa, following a contract win by its authorised agent for the Witbank region, GTB Industrial Services.

The order, won against strong competition, calls for a maintenance crane capable of working within the very constricted area of the dragline house. This contains motors and gearboxes controlling the excavating boom and dragline, and large hydraulic cylinders to control the pontoons, meaning space is at a premium.

Condra said: “Condra proved better able than its rivals to meet the complex criteria of the specification, chief of which was the requirement that the hoist be capable of separating completely from the maintenance crane, and moving away along individual roof beams as an independently operated underslung hoist to recover machine components to the central working space.”

The hoist must also be able to independently deliver loads to transport waiting outside the dragline house, should component repair within the house not be possible, the company added.

The requirement was met by designing the crane’s 12.5 t hoist as a beam changing machine, and fitting the crane with an interlock to prevent the hoist from leaving it unless the crane is securely connected to the selected beam, according to Condra. Power to the hoist is supplied via a cable drum instead of by the crane’s cable loop system.

Managing Director, Marc Kleiner, said Condra was able to draw upon previous experience of dragline maintenance cranes, overcoming engineering complexities to deliver a machine that allows a single hoist to carry out work that would more usually be undertaken by multiple units.

“Our design office tabled an innovative proposal that was also able to deliver more working room than our competitors,” he said. “We can quite often pull a rabbit out of the hat when nobody else can, but we think that this time it was also our ability to manufacture within a short lead time that helped win the order (lead time for the contract is just 14 weeks).”

A key component of Condra’s overall design for the crane is its manual beam interlock, which incorporates an anti-derailment limit switch to prevent hoist movement until beams are locked together, the company said.

Besides rendering impossible any movement of the hoist close to the end of the beam, this design also delivers the large tolerances needed to cope with beam movement when the dragline moves position, according to the company. Dragline movement takes place by ‘walking’ on pontoons repositioned for each step, tilting the machine house forward and placing stress on the structure as well as on the crane itself.

A hoist from Condra’s K-Series was chosen for the design because of its adaptability and particularly robust construction, well suited to these stresses, the company said.

K-Series hoists are produced in three main configurations: foot-mounted, underslung monorail and double-rail crab. Fully covered hoists in the series provide lifting capacities to 32 t, while open-drum units have capacities in excess of 250 t (open-drum and closed-drum Condra K-Series hoists are featured in the photo, painted green).

Features on all models include electromagnetic DC disc brakes, standard frame-size motors with parallel rotors, double-acting limit switches, solid bronze rope guides and totally enclosed splash-lubricated gearboxes. Lifting and reeving arrangements include centre lift.

Condra says it will deliver the dragline maintenance crane during the month following the easing of COVID-19 quarantine restrictions.

Trafo powers through at Mpumalanga coal mine

Trafo Power Solutions says it has recently completed a dry-type transformer contract as part of a significant upgrade at a coal mine, in Mpumalanga, South Africa.

This involved the design, supply and installation of two 200 kVA – 22 kV-400 V – dry-type transformers, according to Trafo Power Solutions Managing Director, David Claassen. Housed in specialised IP42-rated ingress protected enclosures, the units were specified by a design house on behalf of the end-customer, the dry-type transformer leader said.

“The contract demonstrated our application engineering capability and our experience in co-ordinating our solution within a larger project,” Claassen said. “This included meeting detailed specifications, and ensuring that our design for the transformers and their enclosures matched the requirements and constraints of the site.”

Trafo Power Solutions also equipped the units with the necessary earth fault protection and surge protection, as well as vibration pads, it said.

“Dry-type transformers are well suited for the coal mining environment, with its hazardous areas and its regulations to mitigate fire risk,” Claassen says. “The dry-type technology uses air to cool the transformers, doing away with the need to use oil as a coolant.”

Claassen emphasised that the absence of oil has advantages for safety, as the oil ignition potential is removed. The units can also be protected against fine airborne coal dust. An added environmental advantage is the lack of oil leaks contaminating the ground or water, too.

Weir’s Cavex hydrocyclones boost yields, production at Yoctolux Collieries operation

Yoctolux Collieries in Mpumalanga, South Africa, has achieved improved yields and production throughput with the installation of a Cavex® 500CVXT20 DM hydrocyclone from Weir Minerals Africa, the OEM says.

Part of the Tala Group, the open-pit coal mine was looking to improve the performance of its dense media separation (DMS) circuit in its Wash Plant 1. The existing 610 mm cyclone, installed during the mine’s initial design phase, had an operational life of only six months between refurbishments.

Members of the Weir Minerals Middelburg branch and hydrocyclone product team conducted a site audit, revealing the incumbent cyclone was operating inefficiently. A “wash-ability” analysis showed that an improved yield could be achieved using the Cavex hydrocyclone technology on the DMS circuit, Weir said, with the customer specifying that the product would have to offer improved separation efficiency, increase wear life and match the existing cyclone footprint.

Following a proposal that included dense media (DM) hydrocyclone simulations, a Cavex 500CVXT20 DM hydrocyclone was installed in August 2017. Manufactured from mild steel, it is lined with 25 mm slip-casted radius ceramic tiles manufactured with 92% alumina content.

To date, the hydrocyclone has achieved higher separation efficiency through an average 15% yield increase, according to Weir. It has achieved an overall average of 75% yield for both of the mine’s coal types – grains and peas. This compares favourably with the 65% achieved previously by the competitor’s cyclone, Weir said.

There has been a 49% throughput increase in production tonnage, from 78 t/h to 116 t/h as a result of the reduced turbulence in the hydrocyclone’s design. The mine has also seen significant wear life improvement, with the Cavex DM hydrocyclone requiring only a spigot replacement after nine months, according to the equipment manufacturer.

So satisfied was the management at Yoctolux Collieries that they placed an order for an additional Cavex 500CVXT20 DM hydrocyclone in May 2018. This replaced the competitor’s cyclone on Wash Plant 2, with the replacement based on the improved metallurgical and operational benefits obtained by the Cavex hydrocyclones.

Concor Infrastructure helps Exxaro beat Belfast coal mine production goal

The start-up of Exxaro’s Belfast coal mine in Mpumalanga province, South Africa, has been aided by Concor Infrastructure’s work on building dams, roads, platforms and other infrastructure, the infrastructure group said.

At work since October 2017, Concor Infrastructure is constructing four major dams, 26 concrete platforms and terraces, 37 internal roads of 16 km in length, and is upgrading almost 13 km of provincial roads, among other aspects at the mine, it said.

This month, Exxaro announced that Belfast had produced its first coal six months ahead of schedule. The mine, which was only expected to start producing coal in 2020, was expected to cost R3.3 billion ($221 million) to build and would be a “first-of-its-kind digital mine”, ranking as the last good-quality A-grade, high-yield coal deposit in Mpumalanga, the coal miner said.

According to Concor Infrastructure Contracts Manager, Pierre van Vuuren, these tailings dams are being lined with both a geosynthetic clay liner and high-density polyethylene sheets, in accordance with the water use licence and related environmental regulations. Various structures around the dams are also being installed, including large silt traps, drying beds, inflow chutes to prevent scouring, and spillways and sumps.

Among the concrete platforms and terraces are two primary crusher bases being built for the run-of-mine crushing facilities. The various structures being built by Concor will demand almost 350 t of steel reinforcing and nearly 2,700 t of bulk cement. Other inputs will be around 15,000 t of 19 mm aggregate and nearly 13,000 t of crusher sand.

Extensive upgrading is being done on the D1770 and D1110 provincial roads – for the transport of coal to the rail siding – including eight major culverts under the roadway, Concor said. For all the project’s road works, almost 9.5 km of subsoil drains are to be installed, as well as 2.7 km of stormwater culverts. G5 and G6 construction material comes from an external quarry and crushing plant about 30 km from site towards Carolina.

Contracts Manager, Mabandla Dlamini, says the project has had a substantial local impact with a core labour complement of about 180 personnel being accommodated in the Emakhazeni municipal district. The overall workforce managed by Concor Infrastructure, with contractors, totals closer to 700 – all of which are transported 30 km daily by the local taxi network.

Dlamini also says various subcontracts are outsourced to local small enterprises, such as drainage, stone pitching, paving, kerbing, fencing, security services and catering. Diesel is sourced from a local fuel depot in Belfast with the project expected to consume about 4.3 million litres of diesel in site-wide applications.

Over 150 items of plant and equipment are active on the site, according to Site Agent, Sarel van der Berg, with about 40 items such as articulated dump trucks, tippers and graders sourced from local plant hirers.

Belfast is expected to produce 2.7 Mt of good-quality thermal coal a year for at least the next 17 years, starting in 2020. There is also potential for a second phase, which could take the mine life to 30 years.