The Magarini Sands, which host the Kwale deposit, are of aeolian origin deposited as coastal dunes after conditions of intense erosion. The poorly stratified deposits form a belt of low hills running parallel to the coast. Heavy minerals (“HM”), mainly ilmenite, rutile and zircon, are concentrated locally and are abundant in some places. The deposits also contain a clay and silt fraction of about 24%.

The general stratigraphic sequence of the Kwale deposit, as seen below, is composed of brown sand at the surface, followed by orange or reddish sand, becoming more beige or pinkish at depth. The base of the deposit is weathered sandstone from the Mazeras Sandstone.

The Kwale Special Prospecting License comprises three mineralised zones, the Central, South and North Dunes, which occur as unconsolidated dunes. Only the Central and South Dunes form part of the Kwale Project.

Since the commencement of the project, mining at the Kwale Operations has been based on a conventional dozer trap mining unit (‘DMU’), using Caterpillar D11T dozers to feed the DMU. The DMU has proved well suited to the Kwale ore, particularly when mining the deeper central blocks of the deposit.

However, when mining the lower grade, thinner perimeter blocks of the ore body, the DMU is unable to achieve the same efficiencies partly due to the need for more frequent relocations between blocks, resulting in increased downtime. As a solution, during the year in review, a 400 tonnes-perhour (‘tph’) Hydraulic Mining Unit (‘HMU’) was introduced to compliment the DMU.

The plants at the Kwale Operations are designed to process ore to recover three separate products – rutile, ilmenite and zircon. Ore is received at the wet concentrator plant (‘WCP’) from the mining units via a slurry pipeline. The WCP removes slimes, concentrates the valuable heavy minerals (rutile, ilmenite and zircon) and rejects most of the non-valuable, lighter gangue minerals. The WCP incorporates a number of gravity separation steps using spiral oncentrators. The heavy mineral concentrate (‘HMC’), containing 90% heavy minerals, is then processed in the mineral separation plant (‘MSP’). The MSP cleans and separates the finished rutile, ilmenite and zircon minerals and removes any remaining gangue.

The Kwale Operation is designed to process ore to recover three separate products – rutile, ilmenite and zircon. Ore is received at the wet concentrator plant (‘WCP’) from the mining units via a slurry pipeline. The WCP removes slimes, concentrates the valuable heavy minerals (rutile, ilmenite and zircon) with a number of gravity separation steps and rejects most of the non valuable, lighter gangue minerals to produce a heavy mineral concentrate (‘HMC’). The HMC, containing approximately 90% heavy minerals, is then processed in the mineral separation plant (‘MSP’). The MSP cleans and separates the rutile, ilmenite and zircon minerals into finished products for sale. Despite the increase in mining volume, production of HMC fell to 708,404 tonnes, lower than the prior period’s 734,431 tonnes due to the lower mined ore grade. The HMC stockpile was drawn down during the year to 83,632 tonnes (139,364 tonnes at 30 June 2016) due to the lower HMC production and increased MSP throughput.

The HMC is upgraded using a combination of gravity, electromagnetic and electrostatic methods to generate marketable products of ilmenite, rutile and zircon. The ilmenite and rutile products are produced in bulk for sale to international markets, while zircon is typically bagged and containerised for export.