Transforming perlite waste residue into construction bricks
50 houses in Argentina have already been constructed with a new type of bricks made with 90% perlite residue - this is a perfect illustration of applying circular economy to the mineral industry.
The Imerys plant in Tucumán, Argentina, has developed a more efficient way to eliminate waste from the manufacturing of perlite, which is essential for several markets, such as filtration, civil construction, and agribusiness - among others. This perlite waste is now used in the manufacturing of brick! Before that, perlite waste residue was used to fill arid quarries, an end-use that met environmental criteria but generated more costs and less value to society.
In 2018, the plant began donating perlite waste residue to a local cooperative called “Los Parceros” (the Partners in English). The cooperative produces the brick in the Tucumán region using 90% perlite waste residue and 10% cement.
Álvaro Alderete, president of the “Los Parceros” Cooperative explains the production steps. “The process begins with the transport of bagged perlite waste residue. We then introduce it to our production lines by adding the cement and water to begin the mixing process. As the mix becomes the right consistency, it’s placed in the hydraulic press - from where the bricks are formed and allowed to dry for a day. After that, they are stacked on pallets and stored for 28 days until they are ready to be used in construction.”
Each ton of perlite waste residue provides enough material to produce 1,000 bricks, which have excellent thermal and acoustic insulation attributes. Because of the high perlite content, the bricks are lighter, easier to handle, and more uniform than regular brick. As a result, the bricks are easier to assemble, which helps speed up the entire construction process. Another advantage is that during production, the bricks can be dried naturally in the open air, without the use of a furnace, thereby reducing energy consumption and associated greenhouse gas (CO2) emissions. While this makes the production process longer, it reduced the overall environmental footprint of the final product.
The partnership started 3 years ago with small trials quantities made with perlite residues to test the possibility of creating bricks. The tests progressed successfully over time and in 2020, the cooperative began production on a larger scale. By February 2021, 40,000 bricks were produced that were used in the construction of 50 houses. The Tucumán plant has the capacity to donate approximately 220 tons of waste per month, which will increase the donation, and with it the production of bricks to meet increased local demand.
“This is an example of circular economy, which benefits the environment, the company, and the surrounding community”, said Jacqueline Correa, Head of Quality and Integrated Management Systems (IMS) of Imerys in Tucumán, "The raw material does not end up as a waste, it enters a manufacturing process again to generate a new product. We are looking for innovative ways not only to reduce the environmental impact of our operations but also to provide the community with sustainable product alternatives.”