For nearly 10 years, we have been working to return recycled glass to its primary state of sand,” Adam Somerscales, who is Alex Fraser Group’s Victorian recycling production manager, said.
“Glass from kerb side collection is broken down and optically sorted into different colours. It is then sold to glass bottle manufacturers, who have strict quality guidelines for recycled glass.
“When pieces of glass are too small to sort or contain large amounts of ceramic, stone and porcelain, this glass is stockpiled. Alex Fraser takes these problem glass fines and processes them to sand for use in drainage and road projects.”
A pilot plant has been used to prove the process and help develop a market over the past six years. In the past 12 months, Somerscales said, Alex Fraser has been looking at ways to effectively separate the glass from metal, sharps and plastics, and increase processing efficiency.
One way is through screening technology.
{{quote-A:R-W:300-I:2-Q:"We discovered a way to enhance the magnetic properties of tiny metallic pieces, and separate them off mechanically,"-WHO:Adam Somerscales, production manager, Alex Fraser Group}}“The process we use for crushing glass is quite similar to how we crush rock, concrete and brick, but the screens used are more suited to aggregate products than glass,” Somerscales said.
“Currently, the steel screens ‘blind over’ if the glass is wet, which means glass will fill in the holes in the 5mm screen where material should fall through. Our new plant will feature screens that vibrate faster and self-clean.”
The company has conducted plenty of research into the magnetic separation of fine metal objects.
“We discovered a way to enhance the magnetic properties of tiny metallic pieces, and separate them off mechanically,” Somerscales said.
The new plant design will potentially increase Alex Fraser’s production capability from 50 or 60 tonnes per hour (tph) to 100 tph.
“Through a long running series of laboratory tests and field trials, we have also demonstrated that we can increase the amount of recycled sand in road base while maintaining the specifications set by VicRoads and have precise mix registrations in place,” Somerscales added.
“The key differentiator for Alex Fraser is our customers trust that we can make a consistent road base, asphalt or sand for their projects, all day every day,” he said.
“By researching different plants used overseas and local scoping and testing over the past 12 months, we have been able to design a fixed plant at our Laverton facility.”
Somerscales said the new plant would include crushing processes and multiple screening and separation processes.
{{image3-a:r-w:250}}Conveyors will link it to the main crushing plant, substantially reducing mobile equipment movement and material handling costs. It will also maintain precise control of mix designs, and maximise the use of recycled sand in all the company’s products.
“This is an intricate project that we haven’t seen anywhere in the world, and there will be lessons to be learnt during commissioning and operation,” Somerscales said.
“The design process has included input from operators, maintenance personnel, consulting engineers and safety advisors.
“We are aiming for an efficient plant that has excellent maintenance access and makes a good product in high tonnages. It will be the first glass recycling facility licensed under Victoria’s new [EPA] regulations.”
The new plant is nearing completion and is due for commissioning in the second half of 2018.
Somerscales said that there is the potential to build more of these plants, but in the short term this one new plant will produce enough raw materials to supply the Laverton, Epping and Clayton plants.
Alex Fraser Group was established in Melbourne in 1879 and is now one of Australia’s largest C&D recycling contractors. Earlier this year the company was acquired by Hanson Australia as part of a sale worth $208 million.
Hanson, which operates quarries nationwide and is part of the multinational HeidelbergCement Group, is expected to use the acquisition of Alex Fraser to expand into parallel industries such as recycling and asphalt.
“Alex Fraser will continue to operate as a standalone business,” Murphy told Quarry at the time of the acquisition. “However, in recognition of the strong synergies in our values and culture, we are focused on bringing Alex Fraser and Hanson people together at every opportunity – to share and learn from each other.
“Hanson ownership also gives Alex Fraser people access to outstanding development and career opportunities.”
Source: Alex Fraser Group