DIRTWHACKER
(AUSTRALASIA)
INTRODUCTION
Conveyor belt cleaning is one of the most important operations on any mine site or processing refinery. Inefficient cleaning leads to spillage of the raw material and this falls to the ground in an untidy and unsafe manner leading to lost production through wasted material and loss in revenue through excessive maintenance costs.
There are many conveyor belt cleaning systems on the market - in principle, belt cleaning looks like a simple job. In contrast it is not.
To achieve optimum belt cleaning the following conditions are required:
As well as implied conditions, such as not damaging the belt, in the event of failure to be fail safe, and to minimize maintenance.
The only effective belt scraping system to satisfy all these requirements is the Dirtwhacker. It is installed as a secondary cleaner and, in most cases, does not require a primary scraper.
HISTORY
The Dirtwhacker was developed in South Africa and is used exclusively throughout many mine sites in that country. After extensive testing and improvements, it is now exported to many countries including Canada, USA, North Africa and Europe. Rojan Advanced Ceramics have been the Australasian agents for Dirtwhacker since 1996, and have steadily achieved great respect in the conveyor cleaning market for providing superior performance and service.
PRINCIPLE OF OPERATION
All competing systems work on a lever type principle as shown in Figure 1 below. With this design, the blade is not at a constant angle on the belt at all times and the pressure of the blade on the belt varies.
Figure1 Lever-type Principle
The Dirtwhacker consists of a set of hinged parallelograms mounted along a common rack with an inflatable rubber bladder running through the middle of the parallelograms as shown in Figure 2.
Figure 2 The Dirtwhacker blades and rubber bladder
The Dirtwhacker's unique parallelogram design (patented world-wide), shown in Figure 3 below, ensures that the blade is always held at 90o to the belt. The internal bladder ensures every blade on the rack is held at the set pressure.
Figure 3 Schematic diagram showing operating principles of the Dirtwhacker.
The Dirtwhacker belt cleaner relies on a blunt scraper blade. This round cornered blade (which cannot damage the rubber) is activated onto the belt surface by the hinged parallelograms and operates at a belt/blade pressure of 40 to 60kPa. This ensures a squeezing action on the belt rubber, encouraging the dirt to drop off the belt before it reaches the blade. This unique action results in negligible carry back and prolongs the life of the blades. As the blade begins to wear, the unique action of the parallelograms and inflatable bladder ensure that the blades are self-adjusting, maintaining a constant pressure onto the belt. A further feature is that all parallelograms operate independently of each other, ensuring maximum life of each blade and each part of the belt receiving equal cleaning opportunity.
IMPORTANT FEATURES
Pressurisation of a rubber sleeve alters the angles within parallelogram modules, thereby providing precise and uniform blade pressure on the belt surface. The system automatically compensates for scraper blade wear. The constant blade/belt angle and even blade/belt pressure over the full belt width are other unique features of the design.
Figure 4 The Dirtwhacker’s unique parallelogram design
INSTALLATION
The Dirtwhacker is installed as a secondary cleaner. Installation is made so that the blades are situated 50-100mm behind the head drum as shown in Figure 5. As the installation is different in principle to all other belt scrapers, Rojan requests that one of their staff be present at the first installation to ensure optimal fitting. This ensures that site operators are trained for future installations. Comprehensive instructions on installation are provided. A set of installation instructions should be followed when installing the Dirtwhacker.
Figure 5. Schematic diagram showing installation location of Dirtwhacker.
Maintenance work is virtually nil with the Dirtwhacker and involves ensuring that adequate air pressure is maintained in the bladder (this can be adjusted safely during operation) as well as a periodic check on the wear of the blades (these are tungsten carbide for extra long life and have indicators showing when blades should be changed).
Custom designed Dirtwhackers can also be manufactured in stainless steel for corrosive environments.
