The Moma mineral-sands processing facility in Mozambique
The heavy-minerals processing project at Moma in Mozambique for Kenmare Resources plc of Ireland is nearing completion. This project is being conducted under a US$265 million EPC (engineering, procurement and construction) contract by a joint venture between subsidiaries of Bateman Engineering and Multiplex Ltd of Australia. An integrated project team based in Bateman Engineering’s offices in Boksburg is handling the project.
The plant has been designed for an operational life of 22 years to process sands containing 4.3 % of heavy minerals composed of ilmenite (81.4 %), zircon (6.4 %) and rutile (2.2 %). An annual heavy-minerals production of about 800,000 t is expected. Moma will be a low-cost producer with the lowest production costs after the existing Richards Bay operation in South Africa.
Kenmare has the resources to sustain production at the initial production level for 80 years and has recently announced a further increase in its resource base of 60 %.
Processing the heavy-mineral sands
The processes used at Moma are based on proven technology. The heavy-mineral sands are mined by dredging a pond using two suction dredges with a combined capacity of 5,000 t/h. The sand is fed to the floating wet-concentrator plant (WCP) where it passes through trommels and desliming cyclones before processing in a twin-stream spiral circuit with a combined capacity of 3,000 t/h.
During the first six months after start-up, while the dredge pond is being expanded, a start-up tailings stockpile will be used for the coarse, sand tailings and a slimes dam for the fine tailings. Thereafter, the two waste streams will be returned under gravity to the back end of the dredge pond or pumped to a land-based stacker complete with cyclones.
The heavy-mineral concentrate from the WCP is transported through a 2,000 m pipeline, and thereafter dewatered and stockpiled on five 4,000 t operational stockpiles near the dry-mineral-separation plant (MSP). Provision is made in the design to expand the stockpiling capacity to provide for emergency and future requirements.
The MSP comprises a 120 t/h fluid-bed dryer; an ilmenite circuit with drum-magnets and electrostatic-plate separators; a wet non-magnetic and rutile circuit with filter, dryer and separators; wet and dry zircon separation circuits; hot-acid leach and zircon blending circuits as well as a roaster plant. The MSP produces four fractions of ilmenite (of which two can be roasted), two grades of rutile and two grades of zircon.
The products are stored in a shed with a capacity of 139,300 t (109,000 t of ilmenite, 11,200 t of rutile and 19,100 t of zircon). Tailings from the MSP are pumped about 5 km and deposited back into the dredge pond.
The wet-concentrator plant and part of the mineral-separation plant acquired by Kenmare from the now closed Beenup mine in Western Australia were important components of the new processing facilities at Moma. Both Beenup plants closely matched the Moma requirements and were in a substantially reusable condition. For Moma, the capacity of the Beenup WCP was increased by the addition of two more cyclones and, at the MSP, rutile- and zircon-processing circuits, a roaster and a hot acid-leach circuit were added. The Beenup plants were dismantled and then transported from the port of Bunbury in Australia, transhipped off the coast onto a barge and beach landed at the Moma site.
Exporting the product
The stored products are recovered by wheeled mobile equipment and fed onto a 2,320 m-long overland conveyor system, with a belt width of 0.75 m and a design capacity of 1,000 t/h. The system includes a conveyor on a 450 m long jetty at the beach. At the end of the jetty the product is transferred onto a purpose-built, shallow-draught self-unloading barge that transfers the products to bulk carriers moored beyond the shallow shelf off the coast at Moma. More details appeared in Bateman Globe, No. 60.
Moma’s infrastructure
The full infrastructure necessary to operate a processing plant such as that at Moma in this remote location was also provided. This included an upgraded 20 km bush track to the site, an upgraded tarred airstrip and a beach-landing facility to offload heavy cargo from sea-going barges that could not be carried by the road system in Mozambique.
Accommodation was provided for about 700 non-local construction personnel. This included more permanent premises for use subsequently by the operating staff at the plant.
Electrical power reaches the plant through a new 170 km overhead-transmission line from Nampula and communication with the outside world is through satellite data systems and cell phones. Water-purification, sewage-treatment and secure solid-waste disposal facilities are provided. A fuller description of the infrastructure is given in Bateman Globe No. 58.
Health and safety
The health and safety of the personnel involved in the project were a prime concern. A total of 8.2 million manhours were worked between early 2005 and May 2007. In that time lost-time injuries totalled three, including, regrettably, two fatalities. As at May 2007, 5.0 million lost-time injury-free (LTIF) manhours had been worked since the previous injury. The overall LTIF frequency rate of 0.07 per 200,000 manhours is well below the industry average and an exceptional performance in such difficult conditions. Malaria, which is endemic in the area, was by far the biggest hazard, with about 600 reported cases and three non-job-related fatalities.
Impact of the Moma project
The Moma project is, after the Mozal aluminium project near the capital, Maputo, the second-largest project to date in Mozambique. Significantly, it is located in one of the poorer and less developed areas of the country where, in full production, it will provide employment for about 500 workers.
More details on the Moma project may be obtained from John Hope, General Manager, Industrial Minerals or Nick Haywood, joint venture Bateman Project Manager, on +27-11-899-9111 or email Industrial.Minerals@BatemanEngineering.com.
VIEW PDF
©
Copyright BATEMAN 2007
