Shawinigan Aluminium (SAI), operator of the cast house at the former Rio Tinto Alcan plant in Shawinigan, was faced with a dual challenge to remain profitable over the long term: reduce its raw material supply costs and improve the environmental sustainability of its operations. In this article, we are giving a glimpse into how the company has deployed innovative solutions to meet this challenge and position itself favourably in its industry.
The challenge: Adapting to changing market conditions
Due to the constant variability in the price of primary aluminium and billet premiums, SAI made the strategic decision to source aluminium scrap to produce a portion of its billets.1
“The market is such that processing costs are increasingly high, while the market premium for the billet is not systematically correlated to cost variations. We therefore had to save money on the purchase of raw materials,” explains Julien Houde-Lord, SAI’s Chief Financial and Sales Officer.
The solution: optimizing energy-efficient technologies
As a result, SAI wanted to develop a 30,000 metric tonne (MT) remelt capacity for industrial aluminum scrap per year. To achieve this, the company studied two technico-economic scenarios aimed at ensuring the achievement of its production and energy efficiency objectives.
Before carrying out the project, most of the aluminium received was in solid form and remelted in the remelt furnace (F7). Part of the aluminium was also delivered in liquid form and poured into the remelt furnace (F7). Tilting furnaces F3 and F4 were then used to prepare the aluminum alloys before casting. Once cast, the billets were sent to homogenization furnaces for heat treatment and optimization of their mechanical properties before sawing, packaging and shipping.
The first scenario was to use the existing preparation furnaces (F3 and F4, see figure “Scenario A” below) to melt the scrap. At first, this solution seemed interesting, since these furnaces were already used to add alloy elements prior to casting (the F7 furnace intended for receiving aluminium in liquid form). However, these furnaces were not optimized or designed for remelting and would have required very high cycle times and energy costs — a major drawback. In addition, this scenario still involved the construction of a new building and the acquisition of a preheating furnace to ensure safe scrap management prior to remelting, which would have significantly increased the cost of this solution.
Scenario B, shown in the diagram below, was the optimal solution and was selected by SAI's team. It is based on the use of two independent remelt furnaces (F21 and F22) with a capacity of 20 MT each, coupled with a scrap preheating furnace that recovers the heat from the two remelt furnaces. In addition to benefiting from the most modern technology in terms of production and efficiency, these furnaces have the advantage of being able to process smaller batches of scrap and thus offer a lower overall remelting cost. Hence, the new cast house can sort, preheat (without a burner), melt, process and transfer the liquid metal to the existing cast house.
Not only did this solution allow for a production of 10,000 MT in 2022 ,annual production is expected to reach 20,000 to 30,000 MT by 2023, allowing the company to meet its production targets while saving annually nearly 2,000,000 m3 of natural gas as compared to the base case. It has also led to a significant reduction in GHG emissions, given that recycling 1 MT of material generates only 0.4 MT of CO2, compared to 3‑12 MT for the production of 1 MT of primary aluminium.
“The main factor in consumption reduction is the fact that scrap remelting will be carried out by a new furnace system with integrated preheating; this system should lead to the consumption of 112 m3/MT, according to the manufacturer’s data, whereas in scenario A, consumption would be 227 m3/MT,” says Julien Houde Lord.
Aluminum remelting area with both high efficiency furnaces and a preheating furnace without burner.
Énergir’s key role in this project
Thanks to more than $175,000 in grants from Énergir and more than $1.5 million in financial assistance from Energy Transition Quebec under its EcoPerformance program, the manufacturer was able to significantly reduce its payback period.
“The ease of access to Énergir’s energy efficiency team and programs is an important advantage in planning a major project. In addition to receiving a non-repayable grant that reduces investment costs, we get quick and effective support from the Énergir team, not only during the planning phase but also during the project implementation phase,” states Julien Houde Lord.
SAI has implemented a win-win solution to ensure its plant’s long-term sustainability and competitiveness by acquiring equipment that allows it to use clean industrial aluminum scrap as raw material and by optimizing the use of natural gas for this process. With these changes, SAI is becoming a true leader in its field and will serve as an example for companies aspiring to become leaders in sustainable aluminium production — in Quebec and elsewhere in the world.
Omar El-Rouby, Eng.
1 SAI's aluminium billets are used namely for medical and diving equipment.