Agriculture, Recycling, Silos

Product knowledge key to quality outcomes

Recycling plastics onshore is more important than ever for reducing waste, with offshore processing opportunities now limited. Increasing the nation’s capacity for efficient plastic handling has become a specialty for Kotzur.

Recycling plastics onshore is more important than ever for reducing waste, with offshore processing opportunities now limited. Increasing the nation’s capacity for efficient plastic handling has become a specialty for Kotzur.

Kotzur’s silos are best known across Australia’s grain-producing regions. However, the company’s understanding of chemical properties has allowed it to engineer storage and handling of shredded plastics.

Pellets and flakes behave very differently, requiring different silo types to avoid eccentric discharge.

ABHR spoke with Ben Kotzur, Kotzur’s chief technical engineer, about the challenges of storing and handling plastics and the considerations which need to go into the design and engineering of silos to be used in the plastics industry.

“Pellets being uniform in shape can be stored in core flow silos. However, the inconsistency in the size and shape of flakes means this type of plastic can be prone to hang up (where pieces get stuck to the sides of the silo) and preferential flow paths resulting in uneven unloading of the silo,” Kotzur said.

Bulk materials present a particular challenge to ensure even unloading. To avoid eccentric discharge when handling products, designing silos to achieve mass flow discharge is critical.

Kotzur’s expertise in silo theory allows it to work closely with the needs of all its clients, including putting products through rigorous testing to understand the bulk material properties and how they will behave when unloading. 

This allows Kotzur’s design and engineering team to identify and ultimately design bespoke silos to achieve flow modes required for specific material types.

Building relationships is key to successfully designing solutions, and Kotzur’s long-time partnership with Consonic Pty Limited demonstrates the importance of a deep understanding of the material being handled. 

Kotzur has partnered with Consonic for plastics material handling and recycling, in Australia and New Zealand, for the last 30 years. Consonic has 50 years of dedicated experience in Plastics with a strong technical, local manufacturing and engineering focus.

Consonic managing director Michael Vincent said the company’s philosophy is based on bringing together experienced teams and partners to deliver quality projects and equipment for our customers across plastic processing, recycling, packaging, food processing, technical plastics and medical device industries.

“Thirty years ago, we changed our approach to bulk material handling and formed an alliance with Kotzur. Our previous partners could not provide us with the level of engineering professionalism and quality of manufacture the plastics industry demanded,” Vincent said.

“To be very honest, I was searching for reliability and consistency, and thirty years on Kotzur continues to deliver both. Today we rely on Kotzur for our material testing, material flow studies and even Engineering Design Certification for our smaller vessels and structures.”

“The recycling sector has been a significant segment of our business in the last five years, and we would not consider any other partner for industrial silos other than Kotzur. The same is true for custom-designed hoppers, structures, mezzanines, truck fill stations, screw feeders and conveyors.”

For Ben Kotzur, product hygiene is a priority consideration when handling plastics. 

Even trace amounts of contamination can result in changes to the mechanical and chemical characteristics. 

To circumvent undesirable properties with the end products, for example, opaque plastic rather than transparent, the company’s long involvement in plastic handling ensures construction material and silo design deliver for its end user.

“To account for the inherent strength of bulk material, silo walls need to be designed to hold vertical loads,” Kotzur said. 

“Again, intimate knowledge gained from testing and experience allows Kotzur to engineer silos that are manufactured to exceed Australian standard AS3774, along with AS1170.2 for wind and AS1170.4 for seismic activity.”

When presented with the difficulties of uneven unloading of flaked plastics Kotzur engineers coupled a screw feeder into the mass flow unloading system. Allowing flow rate control via the feeding mechanism through a variable speed drive gives clients added control and a more reliable discharge of their bulk product, providing greater functionality for clients.

“Another important aspect of using this type of screw feeder with a mass flow silo is pairing it with a Kotzur plane flow hopper, again improving reliability when handling difficult material,” he said.

“When designing systems for our clients there are two main features we take into consideration for reliable discharge from the particular geometry of a hopper.

“We look at the critical outlet dimension (diameter of the outlet) of the hopper and secondly, is the hopper angle.”

Kotzur said it was important to activate the whole outlet area when unloading to ensure the bulk material is existing the silo across the full outlet space. Using a traditional screw to feed from a silo will draw material from one side of the hopper and can result in eccentric discharge, potentially causing catastrophic failure. Kotzur screw feeder design ensures the full outlet area is activated and true mass flow is achieved.

The company’s expertise in silo theory has allowed the business to provide bespoke solutions for several industries, plastic recycling being one of them. The core values of the business, welded with society’s increased demand and expectations of reducing waste, have led to a natural progression, resulting in Kotzur developing over two decades of experience in handling plastics. 

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