Dubal expands potline to meet demand

Global demand for aluminium is increasing at such a pace that even one of the world’s largest manufacturers of the metal has had to enlarge its smelter to keep up. Zoe Naylor visited Dubal’s Jebel Ali site to see how it will produce an extra 100,000 tonnes per year.

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By  Zoe Naylor Published  July 29, 2006

|~|132proj200.gif|~|A labourer at work inside Dubal’s aluminium potline expansion in Jebel Ali. When completed, it will add 100,000 tpy to its existing production capacity.|~|Working close to live cables that are carrying 245 kilo-amps of electricity is never a straightforward task. But that’s exactly what the site workers at the Dubal (Dubai Aluminium Company) expansion in Jebel Ali are doing. Home to one of the world’s largest aluminium smelters, Dubal currently produces around 761,000 tonnes per year (tpy). To keep up with the increasing global demand for aluminium the company is expanding its Jebel Ali smelter in a move that will add a further 100,000 tpy to its existing production capacity. SNC Lavalin is providing engineering, procurement and construction management services on the US $285 million (AED1.05 billion) project. This incorporates the expansion of two existing potlines — a series of electrolytic cells (known as pots) in which alumina (powdered aluminium) is reduced to high purity aluminum metal. Alumina arrives at Jebel Ali port by ship and is taken to the potline and put into the steel pots. From there, a high electrical current is passed through the pots, which causes the alumina powder to melt and become aluminium. This molten aluminium is transferred from the pots into ladles and taken by truck to a cast house on site. In the furnace it is shaped into whatever the customer wants, ready to be exported. SNC Lavalin has been working on Dubal’s Jebel Ali site since 2004 and is currently working on the potline 79B expansion. “Construction of potline 79B started in September 2005 and is due for completion in November 2006,” explains Ghyslain Deschamps, area manager, SNC Lavalin. The potline will be 130m long and will comprise four potlines, adding 128 pots to Dubal’s existing 1,300 pots. “Work on potline 79B is about 75% completed,” he explains. “We are currently doing the mechanical and electrical (M&E) works in the potrooms, installing the pots and soon we will start the pre-commissioning of the fume treatment plant.” SNC Lavalin is currently managing around 2,000 site workers on the 79B project, many of whom are involved in different activities. Civils work, for example digging the trenches, is being done by Al Futtaim Carillion. The electrical contractor is Danway, and Alstom is building the fume treatment plant within the potroom to control the aluminium fluoride gas emissions. The steel contractor on the project is Cleveland Bridge, and Dutco/McConnell Dowell is the mechanical contractor responsible for putting in the pipes and busbars — large, flat strips of copper that carry the electrical current up the pots. “This is a very fast-track project so a lot of things are happening at the same time, which means that coordinating the various disciplines working in the same place is a challenge,” says Deschamps. “On a construction site there is usually three phases: civils, who dig the trenches and do the concrete work; second is the structural steel; and the last is M&E. “This, however, is not like a tall building where there are floors in between the different disciplines — here all three are together.” The steel structure — known as the potroom — which is being built to house the pots for the project calls for 4,000 tonnes of steel and a very thick concrete slab since the pots themselves are installed 3m deep into the foundations. According to Jacques Erasmus, SNC Lavalin’s health and safety manager on 79B, one of the biggest challenges on the project is site safety. “Every morning we have a coordination meeting with the safety officer and we also have an internal meeting to see if there are any safety issues,” says Erasmus. “In addition, we meet with the workers themselves every week — we don’t just talk with their supervisors or site managers. What we try to do is to emphasise the positive — every time we see good safety practice on site, we give the workers a badge. When they have two badges, they are given a phone card.” The system seems to be working well since the 79B project has just clocked up three million man-hours without a lost time incident (LTI). “The fact that the workers come from so many different countries [there are over 25 languages spoken on site] means that reaching this safety record is a real success and is a record for Dubal,” adds Erasmus. One of the biggest safety challenges when it comes to the construction of 79B is that the new potline must be connected into the existing plant’s electrical circuit. This means the site team must connect the new and existing busbars — which on this project will carry the 225 kilo-amp electrical current to the pots. “If you earth yourself and touch the pot, you will disappear immediately — that’s how strong the current is,” says Erasmus. When it comes to welding the new busbar in place onto the existing one, the team has a maximum of just one hour to shut down the plant and complete the work. “If we fail to do so or can’t re-start the pots then we have a major problem,” explains Deschamps. The alumina that is inside the pots is around 500 degrees C — if you take the current away it will start to solidify in around an hour.” Each of the steel pots is lined with refractory material i.e. bricks and mortar to protect the pot shell from the molten aluminium so it doesn’t make a hole in it. “The heat inside is so high that the pots have to be insulated very well,” says Deschamps. “To line one pot alone costs around $1 million. If you freeze one of the pots then you have to break out the alumina that’s inside and you lose the pot.” The busbar connection for potline 79B is due to take place in two stages: one in September and the other in October this year. The team carried out a similar busbar installation and connection last June on potline nine, so it has the experience of how to do it — however it remains a highly technical job. “Firstly, we have to install different kinds of equipment to make sure it’s safe for the labourers to work close to the live busbar,” explains Erasmus. “It also involves a lot of civils works, for example large trenches need to be dug in order to bring the new busbar up to the existing busbar because it’s underground. “Since the bottom of the excavation is below the water level, around minus 2m, we have to use a dewatering system.” While this work is underway, the busbars themselves are being fabricated in the shop on site. “When it finally comes to putting the busbars in place, we hire Clauser, a specialist French construction company, to weld the plates together,” says Deschamps. The Clauser team is mobilised around six weeks before the welding itself is due to be carried out, to make sure it can produce the right quality of work — and can weld fast enough. “We practice a lot to make sure the right sequence and the right timing is achieved,” adds Deschamps. “The quality of the work is vital — in order to carry the current we have to make sure there is a good contact between the plates. But if the positive and negative poles touch one another, the pot can short circuit and explode — and one pot is equivalent to 60 tonnes of dynamite.” Connecting the busbar is the last activity before the live current is brought into the new 79B potline. Aluminium production is then scheduled to commence at the start of November. Dubal was established in 1979 under the leadership of HH Sheikh Rashid bin Saeed Al Maktoum, the late ruler of Dubai. Over the ensuing years it has transformed into a global aluminium producer. Abdullah Kalban, Dubal’s CEO, says: “We are determined to further enhance our international reputation through the continued development of advanced in-house technologies and the pursuit of excellence in all that we do. Furthermore, by placing environmental, health and safety issues at the forefront at all times, Dubal will play a prominent role in supporting Dubai’s quest to achieve sustainable development.” Demand for aluminium has seen a worldwide increase with prices soaring to around $2,800 a tonne in the first half of 2006. Much of this demand is being driven by the rapidly growing Chinese market, which is seeing a sustained growth in construction and manufacturing activities. With the global demand for aluminium predicted to increase even further over the next few years, Dubal’s 79B potline expansion is likely to find a ready market for its products.||**||

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