Mining industry technology and products supplier Tenova Takraf Africa, formerly Bateman Engineered Technology, supervised the commissioning of five bucket elevators at the Moma mineral sands mine, in Northern Mozambique.

The company supplied the bucket elevators to multidisciplinary engineering, project and construction management services company Aveng EPC, which is the main engineering, procurement and construction (EPC) contractor for the Kenmare Resources-owned and -operated process plant at Moma.

The Moma mine contains reserves of heavy minerals, which include the economic titanium minerals ilmenite and rutile used as feedstocks to produce titanium dioxide pigment, as well as the relatively high-value zirconium silicate mineral, zircon.

The Moma expansion project – which the bucket elevators were supplied for – aims to increase the current production capacity of the mine by about 50%, resulting in an increase in production of ilmenite from 800 000 t/y to 1.2-million tons a year.

The bucket elevators are used to elevate heavy mineral concentrate in the dry circuits of the mineral separation plant from the lower floors to the gravity distributors situated on the top floors of the building.

Tenova Takraf’s scope of work included project management and planning, the design, engineering, procurement, manufacture, inspection, painting and documentation of the bucket elevators, as well as loading them onto the client’s transport system.

Tenova Takraf supplied five new elevators, but also made modifications to another 15. “These modifications entail changing the elevator dynamics to enable them to be used at the increased tonnage rates,” says Tenova Takraf project manager Hector Matake.

He adds that this was achieved by modi- fying the head stations and changing the discharge characteristics by modifying the speed and bucket design.

“It was a difficult order from our side,” says Aveng EPC mechanical engineering manager Jacob Poulsen.

“It was not simply the delivery of new elevators, but also the refurbishment of a large number of elevators. There were several challenges to overcome, but, overall, it went well. We received high-quality drawings and good technical support from Tenova Takraf, and the design sheets received from them were comprehensive and contained detailed information,” he says.

Tenova Takraf senior product engineer Andrew Wager says that design challenges lay in re-engineering the existing bucket elevator machines to ensure that they meet the increased throughput. Timely delivery of equipment is critical as the client has specific dates for shipping equipment to Mozambique. “Despite this, the project team’s focus and commitment ensured delivery in the agreed time frame,” he says.

The main elements of the expansion at the Moma mineral sands mine include an upgrade of the capacity of the existing two dredges and wet concentrator plant to increase spiral feed capacity from 3 000 t/h to 3 500 t/h and the installation of a second wet concentrator plant with a spiral feed capacity of 2 000 t/h in a separate dredge pond, using a new third dredge on the Namalope reserve.

It also includes the addition of a wet high-intensity magnetic separation (Whims) circuit at the front of the ilmenite circuit of the mineral separation plant. Whims technology is commonplace in the mineral sands industry and is used to separate magnetic and nonmagnetic fractions in the heavy mineral concentrate while in a wet state. This will replace the dry primary separation stage and its associated costs.

The existing mineral separation plant will require some modifications, including an auxiliary 80 t/h ilmenite circuit, to increase throughput capacity from 135 t/h to 220 t/h.
An upgrade of the product storage facilities to increase capacity of final products from 140 000 t to 220 000 t will also be undertaken.

Tenova Takraf is a key supplier of equipment and systems for openpit mining, underground solutions and bulk handling, having provided several complete systems and individual machines for clients globally.