FINLAND – The Allu Group, manufacturers of multi-purpose attachments for heavy equipment, now offers a dredging solution that reuses the removed material. If the company’s success at a historic canal in New Jersey is anything to go by, miners can look forward to using the same technology for their drainage ditches.
The dredging is taking place at the Delaware and Raritan Canal that provides water to millions of New Jersey residents. Sediment from road and land runoff is deposited in the canal, which periodically requires the sediment to be removed.
The stabilisation method used on sediments from the canal is a quick, mobile and cost effective solution to making the canal dredging reusable, and consists of three parts. The first is the Allu Processor which is a versatile hydraulic accessory for excavators; the second is the Allu PF Pressure Feeder, which feeds the binder (in this case, Portland cement) through the hose. The third is the Allu DAC, Data Acquisition System to measure, control and report the stabilisation. The latter enables the control of all the functions of the PF unit as well as also saving the data during the stabilisation project, thereby providing the facility to transfer data onto other computers for quality control purposes.
The main part of the system is the Allu Processor itself. This is an attachment for a conventional excavator, powered by the excavator’s hydraulic system, thereby converting the excavator into a powerful and versatile mixing tool. The mixing drums penetrate and mix a variety of material in situ, meaning that materials can be mixed anywhere the excavator can go, thus capitalizing on the excavator’s mobility and articulation to reach difficult or soft areas.
In the case of the canal project, the Portland cement is delivered directly to the area of the highest mixing shear by an attached 80-mm diameter pipe, injected via a nozzle located between the mixing drums. The Processor penetrates through any hard crust layers and mixes the dredged material with the Portland cement effectively, with penetration and mixing effectiveness being enhanced by the angled position of the drums which minimises the ‘dead’ area at the bottom frame.
The dredged material consists of varying mixtures of sands, gravels, silts and clays, which are ideal for reuse in a variety of applications. The added Portland cement helps dry out the material and gives the finer material more strength when used to reclaim a brownfield site.