Colloid Mill for Asphalt Emulsions
Now asphalt emulsion plant owners have an additional choice. It’s a new mill for asphalt emulsions, marketed under our brand name Barracuda™. Our engineers thoroughly researched existing designs to see where improvements could be made. Consequently, our new mill employs special features created to overcome known drawbacks of other mills.
The Barracuda mill mixes virgin asphalt with a water/chemical solution to produce a stable, homogenous material, either cationic or anionic.
It has the ability to produce 15,000* gallons of emulsified asphalt per hour in a single pass through the mill. It is powered by a 150 hp electric motor. Other sizes of mills will soon be available.
Mixing in the mill takes place in the gap between the two mill plates. One plate is mounted on the stator and remains fixed during operation. The other plate is mounted on the rotor and spins at 3600 rpm. The liquids are combined by the action of the plates. The gap between the plates can be adjusted to produce the optimum mixture.
The plates have 100% machined surfaces and are precisely made from stainless steel.
The gap between the mill plates is controlled by the position of the stator. The stator is adjustable, unlike mills with adjustable rotors. The adjustable stator avoids inherent problems with seals on shafts of adjustable rotors. Adjustments can be made while the mill is running—a unique feature of this mill.
Adjustment of the stator is achieved using a self-locking worm drive. Manually rotating the worm moves the stator 0.002-inch each turn. Total adjustment is 0.375-inch or 187.5 turns.
The worm shaft is supported by precision bronze bushings that do not require lubrication.
The worm shaft can be rotated with an ordinary wrench to adjust the position of the stator.
A digital readout system using quadrature encoder technology indicates the gap between the mill plates for easy, precise (0.001-inch) adjustments of the gap.
LONG LIFE SEALS
The rotor shaft in the mill uses seals highly suitable for production of asphalt emulsions. Three seals are used. Two are lip seals used on the shaft in the rotor shaft frame. The third is a common, spring-loaded face seal used in the mill chamber. It is standard equipment.
The seals are not adversely affected by recurring expansion and contraction. For example the shaft elongates as much as 0.015-inch at the rotor seal due to thermal expansion.
BEARINGS AND LUBRICATION
The rotor shaft frame houses and supports the rotor shaft. The shaft has bearings at each end of the frame. The bearings permit elongation of the shaft as it heats.
Lubrication of the rotor shaft in the frame is critical for long bearing life. Lubrication is achieved by a simple, closed loop system with a 1/2 hp motor. The lubricating oil is filtered as it constantly circulates through the frame and is returned to its external reservoir by gravity. It is unaffected by temperatures in the mill housing and does not need water cooling used on some mills.
Heatec is producing a new skid for production of asphalt emulsions. It contains Heatec’s new Barracuda colloid mill and related systems. It has an automated PLC control system with touch screens.
The mill is heated by hot oil from an external source. It emulsifies a mixture of asphalt, latex and a chemical solution.The ingredients of the mixture are precisely metered.
A conventional Heatec metering package, which consists of a pump pushing a pump, meters the hot liquid asphalt. The asphalt is filtered through a strainer and controlled with an air actuated valve.
The latex and solutions systems are each controlled by an actuated valve and Siemens flow meter.
A variety of touch-screen controls are available for the skid.