Modern Mining December 2019

RARE EARTHS

Contractor mining is envisaged for the operation. Wood has identified reputable contract mining and earthmoving con- tractors with operations in Angola or the wider region, who have supplied budget quotes on the basis of preliminary mining schedules. Two contractors have pro- vided quotations and nominated mining equipment. Both contractors nominated 70-tonne hydraulic backhoes as the main excavation equipment and either Mercedes Benz Actros 25-tonne payload tippers or Bell B45E 41-tonne payload articulated dump trucks. The proposed plant will produce a high grade NdPr mineral concentrate to be shipped from the rail siding at Longonjo station located 4 km to the north of the project. The flowsheet adopted for the plant design is supported by testwork

data and incorporates mechanical equipment with a proven track record in the industry. The plant design does not feature sophisticated control systems in keeping with the desire to have a plant that is simple to operate and maintain whilst being able to accom- modate variable feed mineralogy. The Longonjo flowsheet includes the following major process operations:  ROM feed handling – mineralised feed receival and oversize rejection;  comminution – open circuit primary milling fol- lowed by closed circuit ball milling and size classification using hydrocyclones;  pre-flotation – removal of barite and other minerals;  rare earth flotation – rougher plus four stages of

also the potential to extend the near surface blanket of weathered mineralisation in several areas where it remains open along strike through additional drilling. The thick blanket of friable mineralisation at surface lends itself to excavation with hydraulic excavators. Haulage of plant feed and waste to their respective destinations is proposed by small haul trucks. A bench height of 5 m has been selected to suit the geometry of the mineralisation and the read- ily available mining equipment. The benches can be mined in 2,5 m flitches, where it is warranted by increased selectivity. The plant feed will be hauled to the ROM pad and dumped on dedicated stock- piles. Plant feed blending is achieved by a front-end loader feeding the primary breaker.

Reverse circulation drill rig at work in November 2019.

The Longonjo project is located adjacent to the US$1,8 billion Benguela rail line linking it to the Port of Lobito.

22  MODERN MINING  December 2019