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Every recycler knows that the success of their operation depends entirely on the quality and efficiency of their sorting processes.

Melimax, a construction and demolition (C&D) recycler based in Châteauguay, a suburb of Montreal, had been struggling with efficiency issues at its plant for the past few years due to poor performance of the sorting system which required multiple passes for the same material and a large number of manual manipulations. sorters.

“We had quite a few issues with our old system, but the main issues were double and triple handling of the material to bring it up to purity standards, while having a huge number of pickers. Our goal was to reduce our number of pickers as much as possible while having a “one in, one out” system where everything that entered the system came out as an end product or waste,” says Mario Landry, president and owner of Melimax. .

In early 2020, Landry began consulting Sherbrooke OEM about possible solutions to these problems. According to Billy Brasseur, marketing director at Sherbrooke OEM, the company proposed to implement a new sorting technology at the Melimax site in order to increase their recovery rate for materials over 2 inches and fine materials, as well as than reducing labor costs.

At first skeptical, the management of the establishment quickly became enthusiastic about the first technical sketch and the financial provisions of the project. According to Brasseur, Sherbrooke OEM mapped the entire project and shared very detailed plans, not only technically, but also in terms of the financial implications of the project centered on improving recovery rates.

After initial discussions which enabled the company to see the benefit of upgrading the site’s equipment, Melimax signed a complete overhaul of the sorting system.

The manufacturing and design of the system began in May 2020. Installation began towards the end of June and was completed in early October last year. Melimax began operations with the new system as soon as the installation was completed.

According to Brasseur, “The system was built from scratch. We didn’t use anything from the old system. The main difference between the new system equipment, however, was the implementation of optical sorters as well as various equipment to sort the fine part of the material.

A thing of sight

Until recently, in the C&D universe, only large pieces of wood could be easily salvaged, says Brasseur. This changed with the advent of more sophisticated sorting methods.

According to Brasseur, in order to help Melimax better recover its wood, the Sherbrooke OEM recommended the introduction of optical sorters, which have proven themselves on other C&D sites.

According to Brasseur, optical sorters are ideal for this application because they have the capacity to perform hundreds of thousands of ejections per hour. This sorting method has a capture rate of between 95 and 98 percent, depending on the company.

“Now every piece larger than 1/8 inch is salvageable, which is a huge step forward as it now allows the wood salvage rate to exceed 95% in C&D facilities,” said he declared.

According to Brasseur, the ability of optical sorters to differentiate between desirable and undesirable materials is one of the main selling points of the system.

“There will always be unwanted material that will be ejected along with the desired material. We call this the drag factor, and it’s often overlooked when talking about sorting, when in fact it has a substantial effect on the capture rate and purity of your material. The drag factor is caused by the unwanted material being either too close to the desired material or simply attached in some way to the desired material.

Brasseur explains that when programming the ejection parameters of the machines used at Melimax, the company made sorting out some of these unwanted materials a priority.

“By replacing manual quality control with optical sorters, it was possible to increase the quality of the wood, as well as to sort melamine, waferboard and plastic, which allowed the production of two grades of wood distinct with interesting value,” he added. Explain.

Feel good

With respect to fines processing, Sherbrooke decided to design the system as it had done for years in the southern United States, that is, to remove 1/8 inch fines from the remainder of 0 – to a 2 inch portion of salvaged material. This was done to recover not only the wood from this fraction, but also the aggregates, which made up a substantial part of the material.

“Starting up the Melimax installation made us quickly realize that [separating the 1/8 inch fines from the 0- to 2-inch portion] reduces the total volume of material from 0 to 2 inches from 30% to less than 15%,” explains Brasseur. “Furthermore, observations to date continue to demonstrate that there are as many aggregates in the 0-2” fraction as in the 2″+ portion, which is not negligible given that [that portion of the 0- to 2-inch material] is usually not recovered at all.

Landry says that thanks to improvements to its sorting system, Melimax is now able to process 50 tons per hour, or an average of 400 to 800 tons per day. Not only have the improvements to the site resulted in better material recovery, Landry says the new system has helped the company better market its products.

“The first improvement we saw was that we reduced the number of our pickers to five from our original number of 25, which was a significant expense for us. Not only that, but we obtain a better quality of our products with the Sherbrooke OEM system since it is fully automated. We also saw an increase in our availability and throughput per hour,” says Landry. “Perhaps the biggest advantage we have with this system is that fine materials are sorted. Being able to recover both wood and aggregates from this fraction has had a big impact for us. »

This article originally appeared in the March/April issue of Construction & Demolition Recycling magazine. The author is the editor of Construction & Demolition Recycling magazine and can be contacted at [email protected]