Rapid International Ltd

New Aggregate Feed System
The existing bin outlet feeders were replaced with new belt feeders, controlled by variable speed facility for accuracy in weighing. Underneath the bins, Rapid fitted a new weighed belt conveyor, supported on load cells, designed to accept the new batch size. When the batch has been weighed up, it is discharged into a mixer-filling skip hoist, bringing the material up to the mixer. For Brett, this results in more accurate dosing, less waste and more importantly, better quality concrete.

The Mixer
The new Rapid 3-door R1500 pan mixer produces 1.5m3 batches of semi-dry concrete. It is faster and more efficient than the previous one, resulting in a much higher output. It has a holding hopper beneath each door for each colour of concrete produced. Each of these hoppers has a variable level control, allowing the re-order level to be changed, according to the rate at which the concrete is used. This effectively guarantees continuous fresh concrete delivery to the press.

Access hatches are provided on the mixer (gulled winged lids opened by pneumatic cylinders) and the holding hoppers to allow access for maintenance. All the hatches are fitted with trapped key interlocks, requiring isolation of the mixer motor and pneumatics before entry.

Multi Colour Mixes
On the outlet of each holding hopper is a belt feeder with variable speed drive. This discharges onto a collecting conveyor to the press hopper. The conveyor has a reversing facility, allowing any unwanted concrete to be removed from the system. The belt feeders can be operated in various sequences to produce multi colour mixes.

Pigment is batched in powder form, from big bag dispensers, into a weigh hopper above the mixer, for consitent colours. Big bags are lifted from ground level up to the 2nd floor of the mixer platform using an electric chain hoist.

PIL
The PIL control system allows automatic control of the blending sequence, weighing and mixing. The system has modem access for production reports and data exchange with Brett management systems and also online technical support from PIL Head Office.

Result
The improved plant has resulted in Brett Landscaping producing a higher quality of concrete block paving. In fact 175,000 blocks are produced every day, which is the equivalent of a football pitch. The new Rapid mixer enables a much wider range of colours to be made and the surface texture of the blocks has also greatly improved.