The in-house design of National Asphalt’s new asphalt plant at its Laezonia site north of Johannesburg will give customers the comfort of lower environmental impact while still enjoying competitive pricing of asphalt supply.
The 120 tonne capacity plant, which has boosted the company’s capability in the region, incorporates several tried-and-tested improvements based on the company’s extensive industry experience. According to Dave Bennett, general manager at National Asphalt, among these is better burner fuel efficiency and reduced hydrocarbon emissions.
“The plant design reduces emissions from the combined aggregates, efficiently burning this up before it goes to the bag house,” Bennett says. “This gives our new installation a far cleaner and environmentally friendly stack than a conventional plant.”
Dust is removed using both a pre-cleaner and a bag house. In the pre-cleaner, material sized between 0,6 mm and up to 2 mm is dropped into a rotary valve, from where carefully controlled volumes are fed back into the plant. Material smaller than 0,3 mm, and right down to 0,075 mm, is caught in bags, removed using pulsing and similarly fed back into production.
Recognising the growing importance of using recycled asphalt (RA), the innovative design of the new National Asphalt plant employs efficient heating methods to reduce environmental impact as well as fuel costs.
While many plants in the market use super-heated virgin aggregate to heat the RA, the super-heating process consumes considerable fuel resources. Significantly, the design installed at the National Asphalt Laezonia plant does away with the requirement to super-heat. This has been done by ‘scavenging’ heat through both conductive and radiant heat transfer to the RA and the combined mix.
“The plant is built according to specifications developed by National Asphalt over time, and which represent the best value to our customers,” Bennett says. “Asphalt users in and around Gauteng can now benefit from the increased efficiency, economy and environmental benefits of our new facility,” he concludes.