BROONS Hire (Broons) has eked out a small but significant living catering specifically to the market for equipment for unsealed roads, both in Australia and overseas, and the company has made a significant contribution in the areas of compaction and mobile crushing.
Starting as a hire company Broons moved into manufacture with the Rockbuster, a trailed rock breaker introduced to Australia by Coates, who subsequently lost interest in the product, the design for which had not been registered.
While fulfilling a South African export order for a Rockbuster Broons was exposed to the 13.8t “Square” impact roller for which it was assigned the international rights (outside South Africa) in 1985. This became a huge success for Broons in Australia and around the world.
The hammermill action of the portable Rockbuster is designed to do the work previously done by stationary crushers found in a quarry, and produces an angular material that resists ravelling on unsealed roads. Tests have shown that the Rockbuster can achieve a –40mm result in one pass. This avoids the problem of hand-picking oversize rock from spread run-of-pit ridge gravel and stockpiling it by the side of the road, which creates a potential safety hazard. Oversize rocks are also prone to movement to create potholes if they are left on the road surface, either on an unsealed road or under a spray seal.
Infeed rock up to 500mm can be handled with the Rockbuster. Working best with a full chamber, the Rockbuster can handle hard material that few in situ crushers will handle.
Broons has also been active in building, refurbishing and hiring grid rollers. While grid rollers were designed to compact wet material, they have found abundant use in breaking rock.
Broons cautions that this is only effective in certain conditions. The size of rock should be limited to –200mm; a travel speed of 10 km/hr needs to be maintained for the grid knuckle to make the desired impact on the rock; breaking needs to take place on a hard surface (ideally a pad) so that the rock is broken rather than pushed into the ground; and the rock needs to be soft or have natural fissures to fracture easily. The grader operator working with the grid roller should continually blend the crushed rock to ensure a satisfactory grading and avoid leaving potential failures in the pavement.
Searching the world for a machine that filled the gap between the grid roller and their well-proven Rockbuster, Broons found the Kirpy range of specialist rock crushing equipment manufactured in France. The tractor-mounted rotary sizing attachment is more productive than a Rockbuster in some applications (150-200 m3/hr v 60-80m3/hr) and better able to handle abrasive material. Unlike the Rockbuster it can process material below ground level.
The Kirpy has a solid steel heavy duty rotor with fixed carbide-tipped hammers that crush material against replaceable crushing plates in the roof of the chamber and against a hydraulically controlled rear anvil. The Kirpy can handle windrows up to 500mm high and 1.2m wide.
Between the grid roller, the Kirpy and the Rockbuster, Broons believes that it has a suitable option for producing graded crushed stone in situ for use on unsealed roads in all types of materials. While portable crushers are ideal for large volumes they have high mobilisation costs, thus requiring large volumes of material to be processed at the one time.
Broons has already contributed design input to the Kirpy, liaising with the factory and undertaking R&D when this was previously impossible during the European winter.