Before mining companies embark on detailed discussions with transshipment operators, consultants can provide some useful guidance and information. Andrew Keith and Paulo Cardoso de Campos of Aurecon spoke with AJM's Mike Foley.
Mining infrastructure leader at Aurecon, Andrew Keith, ran through some factors important to transshipping operations, such as location, sea conditions, water depths and project life.
"The fundamental question for transshipping is 'can we easily get to deep water?' If the answer is yes, and you can build a port with access to deep water easily and cost effectively, then you wouldn't even consider transshipment," he said.
"However, smaller operators might be in a location where access to deep water is a long way distant, or they don't have the capital to spend on dredging and other infrastructure."
By way of example, Keith said "In the early days of the Indonesian coal industry, when the operators were producing between 500,000tpa up to about 2mtpa of exports, they all did offshore transshipment with geared Handymax vessels using the ships' gear to load the coal."
But there are more options available for miners looking to transship product now. Keith explained that there are many factors that determine the specifications of a transshipping system.
"Transshipment operations are quite limited in capacity. They are getting more efficient as time goes on, but there is probably a practical limit to their application. The throughput is dictated in terms of the cycle pick up, move, dump into the hold, go back, and pick up again. This limits how much throughput can be done by cranes.
"Then you go to the floating transhippers with shiploading booms and so on. They are limited by the unloading rate of the barges.
"Some operators try to compensate for that by having additional storage on board, and then when loading does not keep up with the rate, they draw from that. Also, the rate of the conveyor that goes to the shiploading boom is a limiting factor.
"The largest floating transshipper I have come across in practice so far is about 4,500tph peak loading rate. Shore based loading rates of 10,000tph are not uncommon these days.
"You have got this issue, because it is floating, to make the transshipper bigger you have got to compensate to keep it balanced and working in a sea state and all of those things. That is the challenge of going to larger capacities.
"One company, Adaro, has looked at having multiple floating cranes, but that can be expensive. And there are logistical problems with how many cranes you can get around the vessel and how many barges you need to invest in to feed it."
Keith said another issue to consider with transshipment for large volumes, in comparison to using shore based facilities, is that some shore based facilities will still be required to support the offshore transshipment operation.
"You have a handling cost at the shore based facility and an additional cost at the floating facility, so your operational costs will be higher.
"In this instance, Sea Transport's floating harbour terminal (see later story) has the potential to be an innovation in the industry, as it reduces the reliance on onshore facilities.
"It has the potential to make transshipment more accessible to large volume offshore transfers, but it remains to be proven at this point," Keith said.
Aurecon project manager, Paulo Cardoso de Campos, specialises in pit to port solutions. He has been in Australia for about a year and previously, while working in Canada, designed a transshipping system for London Mining in Sierra Leone.
Describing the service Aurecon offers miners investigating their supply chain options, he said "we are not the operators and we are not the miners. We are between both and it is always interesting how things change when we get involved, because we look at the alternatives and different technologies and so on.
"Sometimes the transshipping operators just want to sell their service and aren't interested in looking at any alternatives. That is not always the best outcome for the client.
"With transshipping, you don't see the money you have to pay now, because that will be the operational expenditure. But as soon as you start to operate and generate revenue, then you say 'I have a lot of money. Where can I make more?'
"You will realise that transshipment is one of the most costly things and usually a miner is locked into a long contract with an operator."
De Campos ran though some considerations a miner should be aware of when considering transshipment. He said third party operators are required to facilitate the transshipping.
"This will mean miners don't fully control their supply chain from the beginning to the end. If you have a transshipping operator, you have to examine their safety record and performance and all those sorts of things, which adds another thing to check during the evaluation."
De Campos explained that when ramping up the size of an operation, there are several key points to bear in mind. To plan effectively, it is important to know what capacities will be years in the future, he said.
"For example, if you are transshipping 5mtpa and you want to increase to 10mtpa, you may be able to duplicate the fleet and equipment.
"But there needs to be certain logic, because if you add too many barges or tugs, the traffic on the water is getting congested and the benefit will diminish.
"In that case, you have to go to bigger barges and bigger boats, or change the equipment so you don't go to a floating crane; you use floating storage instead perhaps.
"With London Mining for example, we designed the system to handle around 4.5mtpa or so, but we knew they would begin by producing about 2mtpa."
This article first appeared in the Australian Journal Of Mining, June 2012.