WORLD PROSPECTS
Anglo updates on continuous mining
In a recent interview, IM again spoke to Donovan Waller, Anglo American Group Head of Technology Development, on the group’ s latest progress on a range of important projects with a range of key mining machinery and technology OEMs. While these are difficult times for Anglo American and the whole industry, the learnings from these underground cutting and rapid mine development projects are vital to the future of underground operations in an era of deeper mines, lack of skilled workforces and an ever increasing focus on removing people from active mining areas.
Based on an Australian patent for oscillating-disc cutting, Joy Global developed a machine prototype in South Africa going back several years. After extensive cutting on surface in UG2 and Merensky orebodies, the proof-of-concept underground trial has been completed at the Bathopele mine of Anglo American Platinum. To cut a rectangular opening, the machine used tungsten carbide inserts in a oscillated cutting disc arrangement and in an undercutting mode. It also successfully demonstrated the use of a vacuum system for collection, transport, and material handling directly onto the mine conveyor belt system.“ The experience and knowledge gained during this trial provided invaluable input and knowhow for the future hard-rock cutting machine design. The collaborative work on a cutting system is continuing with Joy Global.”
Another technology development partnership has been formed with Atlas Copco to create a rapid mine development system( RMDS). On this concept, the TBM-style disc cutters are mounted on a horizontally rotating cutter head that protrudes from a roadheader type of mining machine. In this arrangement, the RMDS shows the distinctive features of a TBM, but excavates a rectangular-shaped tunnel, which is important for roof stability purposes in South African platinum mines, as well as providing the flat floor needed by mine vehicles. The ore removal system is mechanical, via two internally integrated conveyors. The RMDS is now undergoing a functional and operational test program.
On reef mining, building on the solid knowledge base gained during the years of trials of the ARM1100, Sandvik and Anglo American joined forces to work on the next stage of the undercutting narrow reef miner’ s development. The trial of the MN220 started at Anglo American Platinum’ s Bathopele mine in 2013, and after the successful achievement of the proof-ofconcept phase’ s KPIs, the development work is now
El Limón mine linked with RopeCon solution
The new Slot Borer cutting system is based on proven raise-boring technology and deploys the TBM-style steel discs in a compression cutting mode
concentrated in two directions: optimisation of the cutter arrangement as well as the installation and testing of the pneumatic ore removal and transport system.
Finally, leading from an early idea to extract ore by drilling narrow orebodies, Anglo American partnered with Atlas Copco to develop a platinum reef drilling system called Slot Borer. The cutting system is based on proven raise-boring technology and deploys TBMstyle steel discs in a compression cutting mode. The system consists of a cutting / drilling machine and a pneumatic conveying system to remove the cuttings and transport them to the conveyor belt. Upon successful completion of functional tests at the factory and the mine site in Sweden, the Slot Borer is expected to be subjected to proof-of-concept trials in South Africa in the near future. www. angloamerican. com
To connect the El Limón gold ore pit with the processing plant it was necessary to overcome an altitude difference of approximately 400 m of steep terrain. Minera Media Luna( MML), a 100 % owned subsidiary of Torex Gold Resources, opted for the Doppelmayr RopeCon ® as a means to transport 1,000 t / h of gold ore into the valley over a distance of 1.3 km. Along with other aspects, safety and environment were key considerations in prompting the decision.
The El Limón-Guajes gold ore pit of MML is located approximately 180 km south-west of Mexico City in the state of Guerrero, Mexico. The ore mined at the two pits of El Limón and Guajes is processed in one central processing plant. The El Limón pit, however, is some 400 m higher up on a steep ridge. During the planning phase, one of the issues that had to be addressed was the transport of the material from the pit down into the valley. Along with the costs, operational safety and the impact on the environment had to be taken into account.
In March 2013, MML decided to use the RopeCon as a means of transport, a system which covers the vertical rise of 400 m and the length of 1.3 km with just one tower structure before unloading the material onto a stockpile. Construction of the RopeCon started in early 2014. Doppelmayr’ s assembly team carried out the job in just six months, accident-free and on schedule. The RopeCon started operation as planned in March 2016. It now connects the pit with the processing plant.
RopeCon essentially relies on a flat belt with corrugated side walls to transport materials of all kinds. The belt performs a haulage function and is driven by, and guided around, a drum at both ends. To account for the great vertical rise and consequently the steep incline between the El Limón pit and the valley, the belt has been fitted with cleats to prevent the material from slipping. Axles are mounted on the belt at regular intervals to support it. They have plastic running wheels attached to their ends. These wheels run on track ropes with fixed anchoring and guide the belt. The track ropes run over tower structures so that this conveyor system is lifted off the ground, leaving only a minimal footprint. The system features three track rope
s
4 International Mining | JUNE 2016