The installation of a paste conveyor system is required that will enable delivery of paste to the footwall orebody. As shown in Figure 1, there is a need to convey the material approximately 375 meters. At the start of the conveyor, a feeding system will be necessary, while a hopper system will be required at the end(see schematic in figure 2).
Cannington Mine is seeking engineering design of the conveyor, feeder, hoppers and related infrastructure. The quote is to be presented in lump sum form.
Background Information
Cannington Mine currently use tailings based paste as the mine backfill, at production rates of up to 300 tonnes per hour. The paste fill is prepared at the surface backfill plant in 9 tonne batches and reticulated underground by gravity. The design tonnage is 300 wet tonnes per hour(wtph). The paste consists of tailings 74% by weight (p80 = 100um), 4% cement and 22% by water. Paste has an S.G of 2.2, a consistency similar to toothpaste and is very sticky. A transportation system is now needed to transport paste across the surface to a borehole situated 350m from the paste plant. Filling of the footwall is required by June 1 2001.
Currently the paste is mixed in 9 tonne batches and dropped into a 7m3 holding hopper. The paste must be placed onto a conveyor in a continuous manner which eliminates spillage, and takes into account the continuous conveyor versus the batch mixing process.
After exiting the paste plant the conveyor must go down an embankment go down an embankment of 20 degrees and total height of 3.5 metres. The conveyor must also pass beneath a raised road approximately 15m wide. Culverts 3.6 x 2.4 x 1.2m long will likely be used.
The motor for the conveyor must be sized accordingly to start with a full load. The motor will also require a variable speed drive. These motors are to be Pope motors.
The conveying system will require scraper and water cleaning systems to eliminate spillage entirely. This water will need to be pumped back to the paste plant. The conveyor will also need a half cover to eliminate spillage. Beneath the conveyor a catchment system may need to be employed for any spillage.
At the end of the conveyer, a hopper system is required to remove any surge within the system, ,maintain a vacuum in the borehole, and lastly to remove any dried material in the case of the conveyor stopping. This hopper system will require air and water, and electrics to operate valves. It must also incorporate a sump pump and concrete bunded area which may be cleaned using a bobcat.
Other requirements of the design include;
Access to the top of the hopper for easy cleaning.
Maintenance of the system must be minimised.
The system must be robust and take into account process variations and /or breakdowns
Deliverables
The following items are required from the service firm;
1. Engineering drawings (GAs) of the feeder, conveyor, hoppers and associated equipment.
2. Construction drawings of civil, mechanical and electrical components
3. Mechanical design of conveyor system
4. Civil design
5. Electrical design
6. Full material specification for mechanical, electrical and civil components.
7. A detailed methodology of approach to construction will be required, including a list of materials and equipment required.
8. The final deliverable is a detailed engineering report with all drawings and a detailed tender document detailing the scope of work.
It is expected that the design is done in close conjunction with BHP Cannington, to ensure a system that incorporates, safety, environment, ease of operation and maintenance.
Deadline for submission is no later than 5 pm, EST 16 February, 2001. Faxed quotes of the submission will be accepted, provided originals are also mailed to site.
Yours faithfully




Mat Revell
Metallurgist

Phone Business (07) 4769 2123
Home (07) 4723 7668
Fax (07) 4746 8555
E-mail revell.mathew.mb@bhp.com.au

Attachments : Figure 1 - Conceptual Layout conveyor system
Figure 2 - Schematic of hopper above borehole.