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Articles from CONSTRUCTION PLANT & EQUIPMENT (469 Articles), RECYCLING (267 Articles), PUGMILLS (24 Articles)

Blending to perfection

Pugmills (or continuous mixing plants) are said to be the way of the future and they can’t be beaten for blending and correcting product. 
The Rocktec pugmill enables quarries to produce modified aggregates with superior grading and consistent performance to meet the standards now being demanded.

Rocktec can configure a continuous mixing plant, with any combination of feed bins and silos, to provide a complete turnkey  solution to the most exacting standards. Al Rocktec pugmills are built to withstand the most arduous operating conditions and provide maximum performance with minimal maintenance. 

A pugmill continuous mixing plant allows precise control over the addition of lime, cement, water, reclaimed aggregates, emulsions, polymers, recycled glass or crushed concrete to natural aggregates. These mixes make superior products in terms of grading and grading curve shape control, particularly better performing road bases. 

The Rocktec continuous mixing plants can handle capacities of up to 1000 metric tonnes per hour of granular or fine material, using either liquid or solid binders. Rocktec pugmills can be supplied as integrated units to provide a complete package for the end user. The mixer forms part of a total system, of which the feed metering is a critical part. 

A recently installed 400 tph pugmill plant has played an integral part in a major roadbase course supply contract for a section of expressway.
A recently installed 400 tph pugmill plant has played an integral part in a major roadbase course supply contract for a section of expressway.
The metering systems are designed to ensure the desired proportions are efficiently and accurately delivered to the pugmill. Aggregates are delivered, by volume or weight, in a “ribbon” stream, to enhance mixing efficiency. 

Rocktec pugmills feature heavy-duty rubber-lined side walls. These walls can be hydraulically or manually hinged and opened to allow unobstructed access to the mixing chamber for inspection and maintenance. The lower quadrants of the mixing chamber are also rubber-lined and can be hydraulically opened. When these “bomb” doors are opened the crust protecting the wearing surface is easily removed to eliminate cross-mix contamination. Moving floor options are also available. 

With all wear surfaces lined with rubber, and hinged for access, inspection, cleaning and routine maintenance is made easy. All additional contact surfaces are lined with ultra-high molecular weight polyethylene.

The solid mixer shafts have oversize arms welded to them. Each mixing plane features four reversible, cast, wear resistant ni-hard paddles, which form the advancing helix.

Discharge is by stockpile conveyor or direct feed into a truck. Rocktec offers a range of proprietary silos (equipped with reverse air filter, over pressure valve, high/low level sensors and fluidisation in the discharge cone) to suit specific system requirements. Silos discharge via rotary valves or screw conveyors. Weigh scales on a cement feed interlocked with aggregates feed control ensure accurate silo discharge rates.

With an advanced PLC, multiple mixes can be pre-programmed into the system. Level sensors will automatically initiate shutdown sequences if any ingredient runs out. Safety interlocks prevent the pugmill from operating if access doors are not locked shut.

One of Rocktec’s customers says a recently installed 400 tph pugmill plant has played an integral part in it being awarded a major roadbase course supply contract for a section of an expressway.

The customer’s plant consists of three in-feed hoppers and high efficiency belt feeders with integrated scales, driven by electric motors using a close-coupled gearbox to deliver the material to the pugmill. Products are discharged via the radial luffing conveyor into a stockpile, or directly into a truck.

The pugmill is a vital tool in ensuring superior grading control and consistent performance to meet the standard now being demanded on road contracts. It enables the customer to quickly produce large volumes of high performance aggregates within spec every time. The customer also benefits from the increased technical capacity and operational flexibility of the pugmill.

The design and manufacture of all Rocktec products takes place at the company’s manufacturing plant in Matamata, Waikato, New Zealand.

Along with design and manufacturing, Rocktec has a site service team readily available for the mechanical installation and servicing of new plants. Its services include process engineering, to identify which products are required to deliver the performance clients need. All Rocktec equipment complies with current Australian and New Zealand electrical and mechanical safety standards. 

Rocktec has more than 20 years of experience in the design and manufacture of quarry and mining equipment and has completed a number of large projects in Australia. •

Source: Rocktec 

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Thursday, 17 October, 2019 1:42am
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