Modern Mining April 2018

MODULAR PLANTS

He emphasises that substantial savings can be achieved by standardising the basic headgear design and employing the proven hoisting systems and technology that are trusted industry-wide. “This design approach even allows us to have accurate estimated headframe costs on hand – for each category of depth and hoisting load – for project planners to build into their feasibility studies,” says Delaney. “And by updating these prices annually in line with related cost fluctuations, mining projects can quickly and easily get access to vital data that would otherwise rely on a lengthy and costly head- frame design process for estimates for a project that may or may not go ahead.” Macnab says the cost-effectiveness of the modu- lar route is likely to raise interest not just among mineral project start-ups, but also among mines that are needing to concurrently ‘clean up’ the environ- mental risk posed by their waste dumps and tailings storage facilities or temporarily increase production. “South Africa does not have a dying mining industry – it is very much alive, and the opportuni- ties are there for modular strategies to be employed both in scalable process plants and in underground mining through headframe and hoisting technology,” says Macnab. 

relocate the facility as the need demands. “The limited footprint of a modular plant also adds to the flexibility of where to locate the facility, and drasti- cally cuts the amount of civils and infrastructural work required on site,” says Bruggink. “Most importantly, the capacity and spectrum of the plant can be adjusted to suit unexpected variances in geology, grade or other fac- tors related to the ore resource.” As the plant is not a permanent fixture, it remains a project asset – to be relocated as conditions demand – rather than a ‘sunk cost’ that may have to be abandoned in a worst-case scenario. “With these and other benefits, the modular option supports a whole new financial model for initiating mining projects in a country like South Africa,” he says. “Consider the value inherent in a rock dump or tailings dam where gold, copper, base metals or platinum group metals have historically been mined; the residual min- eral grades in that material may represent considerable value, especially now that processing efficiency has advanced in the intervening years.” Bruggink highlights the opportunities for a mineral project developer – unencumbered by mining costs – to establish a cost-effective and flexible modular process plant to treat ‘waste’ material as a commercial enter- prise; where such material exists alongside a closed underground or opencast resource, the waste re-treat- ment may even generate the cash-flow to assess and exploit the in-situ deposit. The modular philosophy at METS does not stop at process plants, says Macnab, and extends through to other aspects of the company’s design and project capa- bilities – including mine headgears for underground operations, settlers and crushers alike. “The design, manufacturing and construction of the headframe is another costly and time-consuming aspect of the mine establishment process, so any game- changing mining model must definitely address ways of cutting time and cost on this front,” he says. “That is why we are developing off-the-shelf headframe designs to cater for the two key considerations of almost every underground mine: depth and hoisting capacity.” With the hands-on experience of over 100 headgears during his career to date, METS DESIGN Divisional Director Frank Delaney says it is now possible to offer an almost standardised design for each of four step- changes: shafts of up 500 m; shafts of 500 to 1 000 m deep; shafts between 1 000 and 1 500 m; and shafts between 1 500 and 2 000 m. “The design is based mainly on the depth from which hoisting will take place, so that we know the sizes of the steel ropes (which equates to break strength and sheave diameters), and the production rates required to be hoisted (which equates to winder selection),” says Delaney. “These parameters provide the broad range within which our design will safely accommodate the anticipated loads and forces without the whole design process starting from scratch for each shaft.”

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April 2018  MODERN MINING  41