Interview with Alcoa Innovation New Concept of a Weight-Reduced Aluminum Mega Trailer
Alcoa Innovation, a non-profit organization based in Quebec, Canada, supporting enterprises in their innovative projects based on aluminum, from design to prototypes, developed a concept for an aluminum mega trailer with a payload of 120 MT for a greenfield project of Arianne Phosphate Inc. We talked to Yves Archambault, Project Engineer Alcoa Innovation, and Jean-Sébastien David, Chief of Operations of Arianne Phosphate, about that cooperation.
SPOTLIGHTMETAL: What kind of project is it and why was it started?
Yves Archambault: The mega trailers, with 4 - 5 times the payload of conventional trailers, will be used on remote and private roads to transport phosphate from the mine to the port. The use of aluminum, due to its light weight, will allow the payload to be increased while maintaining the same fuel consumption. Arianne Phosphate, a Canadian exploration company, says this concept will result in fewer trucks on the road after integration, increasing safety and reducing overall environmental impact, thereby improving freight efficiency. In addition, this design will lead to greater economies of scale, reducing the cost of transporting the phosphate concentrate to the port.
SPOTLIGHTMETAL: How did this cooperation come about and when was it started?
Jean-Sébastien David: The cooperation started in 2017 when our Chairman of the Board, Dominique Bouchard who has worked his entire career in the aluminum industry came up with the idea of integrating aluminum in our trailers designed to carry three million tonnes of concentrate of phosphate yearly. He introduced us to the CQRDA (Centre québecois en Recherche et de développement de l’Aluminium). The team from the CQRDA, a member of Alcoa Innovation, based in Saguenay are well connected to the aluminum industry and offer financial support for projects of this kind. They introduced us to Mr. Yves Archambault from Alcoa Innovation and suggested a partnership between Alcoa Innovation and National Research Council Canada. This was realized with the financial support from CQRDA, the Société de la Vallée de l’Aluminium and the reseau Trans-Al and the expertise of our partner Groupe Alfred Boivin, which will be in charge of the transportation of the three million tonnes of concentrate when the mine will be in operation.
SPOTLIGHTMETAL: Which problems has the mega-trailer and how should they be solved with this project?
Yves Archambault: Thanks to the ongoing implication of the fleet operator and the mine owner during the preliminary design phase, it was found that the existing mega-trailers where overdesigned for the transportation of fine powder, almost like talc powder, having a design density of 1500 kg/m3. The mine owner, Arianne Phosphate, is also concerned by the containment of any dust generated by the unloading operation. It was concluded that bottom discharge trailers and a designed unloading dock would be the best configuration making easier the control of dusts. We evaluated the use of standard, road use, bottom discharge trailers in B-Train configuration; it was argued by the fleet operator that the stability of this type of vehicle, on icy roads, would represent a critical concern for the drivers. It must be noted that the geographical location of the mine makes it covered by snow for at least 5 months. In winter, the temperatures will often be around -20°C, with low peaks near -40°C.
SPOTLIGHTMETAL: Which aluminium alloys were considered? And have you considered other materials besides aluminum for the concept?
Yves Archambault: The concept design was based on typical 6061 and 6005A extrusion alloys and 5XXX series plates. It is obvious that further steps in the design will raise questions on the fabrication of parts and casting could represent a viable solution for complex geometries. The economic justifications remain however the absolute leader in our project and a final design is generally a compromise between performance and cost. On the other hand, as Alcoa Innovation has always had a close relationship with the Alcoa Technical Center, in Pittsburgh, US, we might take a closer look at the benefits that would come from using advanced alloys, for instance that for high-strength extrusions or EZCast-NHT™ for cast parts.
As for other materials, yes, steel will be used. Even if the design is in a preliminary stage, we foresee that steel will be needed in the parts that are located in restricted spaces and need to have a sufficient stiffness to reduce the deformation of moving parts. So far, we see that the bottom doors could be in this situation. Due to the geometric specifications of the walls, those doors carry a lot of load and need to be slim and stiff to ensure tightness. We promote the use of the right material at the right place and, in this case, although the use of aluminum makes sense for the overall structure, those doors are more likely to be made of steel.
SPOTLIGHTMETAL: Is it possible to quantify, in figures, how much the payload can be increased?
Yves Archambault: Given the non existence of adapted trailers for this use, , we could not compare the gain in freight efficiency using hard numbers like net and gross weight obtained from a commercial brochure. A lot of work still needs to be done to come up with a final design and a final weight. We used theory to figure out some numbers:
- The aluminum structure represents 50 % of the total net weight of the trailer. The remaining 50 % comes from the axles and a plastic internal coating of the bins to ensure no adhesion of the powder on the metallic surface. At this point we have not considered the weight of any additional accessories like air tanks or hydraulic equipment.
- In theory, a conversion of a simple beam, from steel to aluminum, and based on equivalent stiffness, leads to a weight reduction of 45 % (Ref: Aluminium in commercial vehicles, European aluminium association, page 19).
- Working in the opposite direction to find how heavier a steel structure having an equivalent stiffness would be: We add 45% to the weight of the structure and keep the same axles. The new weight would then be: 50% X 1.45 + 50% = 122.5% heavier than the reference aluminum trailer.
- The relative weight of the aluminum structure over the total gross weight is reduced by 2.7 % when compared to the steel one. This 2.7 % represents the theoretical gain in payload.
- Applying this to the case of Arianne Phosphate, where the target is 120 metric tons per load: a steel trailer would carry a little less than 116 metric tons. On an annual production of 3 000 000 tons, the increase of carrying capacity due to the use of aluminum means a theoretical reduction of approximately 650 trips.
SPOTLIGHTMETAL: When is the integration planned?
Jean-Sébastien David: This was the first phase of our planning to integrate aluminum in the trailers. We have other phases that will lead to the construction of a prototype. The trailers must be ready for the operation of the Lac a Paul phosphate mine.
SPOTLIGHTMETAL: Can you give an initial forecast? How many trucks could be “eliminated” and what exactly does this mean for the environment?
Jean-Sébastien David: The initial forecast is to put 61 trucks and trailers on the road carrying 120 tonnes each. Each tonne we can save in the structure of the trailers will allow us to carry more concentrate. Our estimation is that with two tonnes saved on the trailers structure we will reduce by one truck on the road. Our initial estimate at this point is that the structure can support 150 tonnes, but it needs to be confirmed in further studies. Every truck removed from the road will have a reduction of 890 tonnes of CO2 annually. We have the chance to have a logging road network and we take advantage of this network.
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