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The formal opening of FLSmidth’s expanded facilities at its Delmas Supercenter in Mpumalanga is good news for customers, while boosting the engineering capability of the South African economy.

According to Stephan Kruger, FLSmidth director for Manufacturing and Warehousing in the region, the added capacity of the facility will further contribute to the group’s productivity and customer service while improving stock availability and lead times.

FLSmidth SAGwise optimisation plant solutions

The facility is now double the size it was a year ago, with a total of 10 500 m2 under roof and under crane. The workshop is one of fewer than 10% of facilities countrywide that boasts a 120 t lifting capacity with 11.5 m under crane hook.

“The expansion is aligned with our corporate mission to provide sustainable productivity enhancements for our customers,” says Kruger. “It raises our engineering capability to support local customers, while also improving our efficiencies to compete globally in certain lines of products.”

The Delmas facility engineers components for FLSmidth equipment, as well as whole assemblies and complete plant solutions. The addition of new manufacturing equipment in the workshop – including CNC-controlled six axis machines – will increase the range of items that can be machined on site. The work process has also been optimised to promote quality, reliability, efficiency and cost effectiveness.

The facility’s services include refurbishment, retrofitting and upgrading of existing equipment. It also holds substantial strategic stocks of spare parts such as exciter gearboxes, rotors and stators, as well as wear parts such as screen panels.

“The FLSmidth Delmas Supercenter is a world class OEM facility that consolidates and grows specialist expertise within the South African market, and will create exciting opportunities for the future,” says Kruger. “This expansion is a vote of confidence in the specialised knowledge embedded in this facility, which makes an important contribution to sustaining technical skill levels in South Africa.”

Kruger emphasises the company’s commitment to safety, reflected in the Supercenter’s enviable record of just one lost-time injury since operations began over five years ago. He adds that strict quality control is governed through the ISO 9001 standard and careful environmental management by ISO 14001 with safety to OHSAS 18001.

“FLSmidth’s commitment to continuous improvement is also embodied in this facility,” he says. “We are now in an even better position to play a role in value engineering for the group, particularly in our vibrating equipment and screens.”

In line with the company’s corporate social responsibility, the construction activities last year reached out to local small businesses, he adds. Some 5% of the value of the total budgeted spend was allocated to these firms, ensuring that they benefitted directly from the expansion.

Getting SAG mills to listen and learn

Using acoustic sensors, mineral process specialist FLSmidth has developed an innovative solution for semi-autogenous (SAG) mills that improves milling performance and stability while reducing the cost of wear parts and energy consumed.

According to FLSmidth’s key account manager, Winston Mokoena, SAG mill optimisation demands that the feed rate of material into a mill, the mill speed rate and the water input be carefully controlled. “Too little material in the mill means that critical impacts occur between the grinding media and the mill liners, essentially damaging both elements without producing value,” says Mokoena. “On the other hand, if the mill is over-filled with mined material, grinding becomes inefficient.”

The SAGwise™ total process control solution reduces critical impacts inside the mill by up to 45%, giving longer life to liners, cutting ball consumption and, consequently, reducing downtime for liner replacements or repairs.

At the same time, production levels can be raised by up to 6%, energy consumption cut by a similar amount, and process variability reduced by up to 30%, contributing to smoother downstream operations and a healthier bottom line.

“A significant attraction of this solution is the direct value that it immediately adds to the performance of the mill, which can result in a payback time on the investment of less than six months, depending on the value of the commodity being milled,” Mokoena says.

The SAGwise system employs four or eight unidirectional or bidirectional audio sensors, located outside but in close proximity to the mill, to ‘listen’ for key acoustic indicators of mill performance. To accommodate the extreme conditions in the mill environment, the sensors are encased in secure enclosures. They differentiate between standard, low-energy impact emanating mostly from tumbling action and the critical ball-on-liner impacts that cause damage.

“The system’s data acquisition module then processes the analogue sound signals into a digital signal and sends it to a processing unit where intelligent software and algorithms analyse the sound patterns and adjust the mill feed, speed and pulp density for optimal efficiency,” explains Mokoena.

He highlights that traditional instrumentation and conventional process control loops (PIDs) are not fully up to the task of minimising power consumption, maximising production and reducing liner damage.

“PIDs are reactive in nature and not multi-variable and not sufficiently robust to handle process delays such as those caused by materials transportation, and these shortcomings undermine SAG mill process stability,” he says. “While operators often choose conservative mill parameters, the SAGwise solution provides an electronic system that allows the equipment to run constantly as close as possible to its design limits.”

SAGwise offers an overview of what is taking place inside the mill and also constantly monitors and adjusts conditions to ensure a stable grinding circuit, combining advanced instrumentation with multi-variable process control techniques.

The main parameters that it monitors are mill power consumption, load impacts, mill load and pulp density. It responds to these by controlling the mill speed, the feed rate and the water to achieve an optimal ‘sweet spot’ where the mill runs as efficiently as possible.

Being an open system, SAGwise is versatile enough to implement a solution that is specifically tailored to the needs of each plant; it does this by incorporating the best overall control knowledge and assisting operators in the control tasks on a 24-hour basis.

“What is important to remember is that the benefits emanating from the application of SAGwise go beyond improved mill production and more economical energy use,” he says. “The more stable operation and output of the mill, combined with more uptime, ultimately enhance the performance of the whole plant.”

While improving grinding efficiency, SAGwise also reduces process variability, which has the positive impact of ensuring that the mill provides a constant and optimal feed to the next stage of the process. By contrast, fluctuations in the flow and particle size coming from the mill can cause significant disruptions to downstream processes, in turn reducing the performance of other equipment.

There are a range of control tools available to solve a specific problem, and multiple tools can be applied at the same time within a chosen control strategy. For instance, model predictive control can build mathematical models of process units to verify and estimate controller performance before manipulating the controlled variables.

The behaviour of the SAGwise controller can also be tested and simulated in an on-line environment, where all objects in the controller can be monitored at different levels of detail for easy trouble-shooting.

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Crown Publications, one of South Africa’s largest business-to-business publishing houses, came into existence in 1986. Since then, the company has grown from producing a single magazine, Electricity SA (renamed Electricity+Control), to publishing six monthly magazines, three quarterlies, and a number of engineering handbooks.