Keeping machines moving

The fact that demand for many bulk commodities is currently in the doldrums is well known. In fact, investment bank Goldman Sachs issued a report in February claiming that demand for thermal coal could face an “irreversible” decline.
 
For coal producers, this latest in a long line of grim warnings outlines a future of shuttered power plants, mine closures, and bankruptcies.
 
The support previously provided by China’s growth no longer seems to offer a respite. And while India could add almost 900 Mt of coal demand by 2040, much of that could be met by domestic producers, such that, according to the bank, “the peak and decline in seaborne trade volumes may arrive earlier than we had previously expected”.
 
Such is the fall in demand that Goldman Sachs cut its forecast for thermal coal prices in the key global benchmark of Newcastle, Australia, to just US$45 per tonne in 2018, down from US$48 a tonne this year.
 
Similarly, the price of iron ore tumbled to less than a quarter of its 2011 peak by the end of 2015, as the biggest producers pressed ahead with expansions that were planned when the market was  soaring. At below US$40 a tonne, only a handful of producers – the largest and lowest-cost operations – are expected to ride out the storm.
 
China continues to consume more than two-thirds of the world’s iron ore exports and produces about half the world’s steel. Yet, demand for steel inside China has peaked, many analysts say, leaving the market oversupplied.
 
Taking stock
 
All this spells uncertain times, to say the least, for manufacturers of stockyard handling systems. Equipment orders have slowed, although this has probably hit demand for new units the worst.
 
Stacker/reclaimers, generally, have a longevity that astonishes other cargo handling sectors. It is not unusual to find machines in bulk terminals that have been in place for 40 years or more.
 
Nevertheless, while the basic structure can last for decades, a fiercely competitive environment – and now falling commodity prices – necessitates keeping systems up to speed, in order to sweat existing assets as much as possible.
 
A good example is the most recent expansion phase at Newcastle Coal Infrastructure Group’s (NCIG) export terminal in New South Wales, Australia.
 
The capex programme, designed to add 13 Mtpa of capacity, raising the total to 66 Mtpa, focused on the performance and reliability of its stacker/reclaimers, which are some of the largest in the world.
 
NCIG hired Chute Technology, a Tomago, New South Wales-based engineering group, to conduct a design review, to improve the performance of the transfer processes at each of the four stacker/reclaimers, to enable them to feed more coal from the stockpiles to vessels at the quayside.
 
Coal flow
 
The Newcastle facility has the capacity to unload more than two dozen 7,000t trainloads of coal each day, exporting thermal coal (and, on occasion, metallurgical coal) from the Newcastle, Hunter Valley, Gloucester, Gunnedah and Western coalfields.
 
According to Chute, the review process had to focus on maximising coal flow, while also minimising maintenance on the stacker/reclaimers’ tripper transfer and boom transfer chutes.
 
As of late 2015, improvements on the first unit had been completed, the first step in a process that will ultimately facilitate the movement of coal from stockpile to ship at up to 11,000 t/h, 25% more than previously.
 
The upgrade uses as much of the existing equipment as possible, to minimise costs and installation time.
 
An immediate benefit has been a reduction in product spillage, says Chute, which is a major advantage, given the man hours, expense and lost production through downtime required to correct the problem. Chute Technology and NCIG are also looking to see what benefits might result from smoother product flows on belt life.
 
Go with the flow
 
Improved flow has already been proven in operational service, with the completion of work on the first of four stacker/reclaimers, which was upgraded in a planned operation during the Hunter region rail network shutdown, such that production was not interrupted. As a result of the upgrade’s success, similar enhancements are now scheduled, in order to bring the remaining three units up to the same standard.
 
“The introduction of our series of engineering enhancements on the first stacker was the breakthrough practical step that translated our programme of enhancements into production reality,” said Chute Technology engineer, Dennis Pomfret. “Now, NCIG is replicating that success on the remaining stackers, to realise the total benefit.”
 
NCIG identified that the stacker/reclaimers were the essential link in the production chain that had to be upgraded if the whole chain was ultimately to perform at its best.
 
“NCIG was aware that the conveyors from trains to the stackers – and from the stackers to the ships – could handle greater capacities than the average 8,500 t/h throughput capability of the stacker/reclaimers [which are] at the centre of the process,” continued Pomfret. “So we had to bring the stacker/reclaimer capacity up to the same level to achieve uniform optimum output.”
 
A big task was to fix on going maintenance problems with the two transfer chutes on each unit, the tripper transfer and the boom transfer chutes. The problems here that were frustrating output were spillage and wear at the loading zones of the respective conveyors.
 
Wear was associated with both the skirtboard wear linings and the receiving belts.
 
Root cause
 
The solution was to remove the root cause of the problems, which lay in the poor directional control of the coal and in its flow path through the chutes.
 
The three approaches taken to find a solution were: