Sand Processing

A pugmill with plenty of sting

They are used for optimum moisture content (OMC), which is generally about eight per cent moisture, or making cement treated base for use in higher road specification, for increased stabilisation and longevity.

Local manufacturer Precisionscreen has its own iteration of the pugmill – the Scorpion, and this is one animal with plenty of sting.

It is a versatile machine that can be adapted to work with various applications for mixing. The Scorpion has an output of 300 tonnes per hour (tph) and is capable of doing any main road requirement. The standard machine is suitable for OMC roadbase jobs and is also capable of doing cement-stabilised applications (with the addition of a cement silo).

Unlike other plants, the Scorpion pugmill has an elevated pug head that discharges pugged material from a 3.5m height. This feature avoids the issue of segregation on the belt and makes it easier to clean the main belt, as the material is carried to the pug head dry.

This also allows trucks to be loaded directly from the pug head, and the operator has full control of material flow from the remote control start/stop action in their loader. The aggressive pug head action ensures a homogenous mix of materials.

The programmable logic controller (PLC) enables the operator to select different product mixes at the touch of a button, and the interface is easy to use, showing running tph and water/cement percentages.

There is also the option to add another hopper to blend different roadbase products together. This can help add bottom end or plasticity to the roadbase at a controlled rate.

Working pug

Milbrae Quarries is a family business headquartered in Leeton, in southern New South Wales, that specialises in quarry and concrete products, pre-cast panels and steel reinforcement products.

It operates out of three quarries in Leeton, Walleroobie and Rankin Springs, and three concrete plants in Leeton, Griffith and Narrendera. Its mobile crushing services comprise six mobile crushers that have completed work for 16 shire councils and NSW Roads and Maritime Services, and it also operates a mobile concrete batch plant. The business has now added the Scorpion pugmill to its mobile fleet.

Geoff Beard, the operations manager at Milbrae Quarries, said the key reason for purchasing the Scorpion was that Precisionscreen was “a known, reputable company with a track record of providing excellent back-up service. We are familiar with this model pugmill and appreciated its simplicity in operation and its reliability.”

Beard said Milbrae Quarries was currently engaged with a range of projects that required a pugmill.

“We have a semi-fixed pugmill at one of our hard rock quarries, which has been well utilised, supplying customer requirements aligned to quality materials,” he said. “The mobile pugmill will allow us to extend this customer service at multiple points of sale or at the customer’s site.

“The plant answers several of our business requirements. It can produce roadbase blended to contain our customers’ desired OMC. It improves roadbase grading consistency, providing customers with an improved material. The added blend bin with PLC allows us ease of operation and stringent control on quality, and we can offer modified roadbase blends for stabilisation projects.”

Beard has been impressed with the plant’s capabilities. “It is versatile, has proven reliability and is a rugged design. With a capability of 300 tonnes per hour, the size comfortably addresses the vast majority of our needs without being too large to easily move around.”

Source: Precisionscreen

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