Waste

• Overburden - this is the layer of sand and clay containing little or no ilmenite or zircon, which lies over the ore-rich horizons, and which must be removed before the heavy mineral rich sand beneath can be mined.
• Oversize pebbles and boulders, tree roots and other rubble separated using a screen from ilmenite bearing sand after excavation.
• Tailings sand - this is the left over sand from which the valuable heavy mineral concentrate has been extracted.

A pile of sand from which the valuable heavy minerals have been extracted.

• Iron oxides produced in the Synthetic Rutile plant. These can be converted into pig iron.
• Used acid from upgrading the reduced ilmenite into synthetic rutile. These are converted into sustained release fertilisers and soil amendments.
• Carbon fines produced in the Synthetic Rutile kilns which are recovered and treated in a small processing plant. This produces activated carbon that is used to clean flue gas systems.

The overburden, oversize material, and tailings sand are used to backfill pits created during mining. Because the overall proportion of heavy minerals extracted is very small, the pits are refilled and the land re-contoured close to it original topography.

The iron oxide material is transferred to a containment facility, that is similar to a large dam, lined on the bottom with impermeable clay material and a plastic liner to prevent seepage of contaminated water into the sand below. The water evaporates and leaves behind the iron-rich sediment that is similar to rust. Metallurgists at Capel are investigating technologies that will convert iron oxides into metallic iron that can be sold to manufacture steel. This work included the development of Iluka's own pig iron smelting process.

Tapping Iron and Slag from Iluka's Pilot Pig Iron Furnace

The used acid is neutralised with lime and is stored in dams similar to the iron oxide. This material has been developed in association with Agriculture WA, into a sustained sulphur release fertiliser called Iron Man GypsumTM that has major advantages for pastures on the coastal plains of SW Western Australia. The material has also been found to have excellent phosphorus absorption properties and when used as a soil conditioner or amendment will reduced the leaching of nutrients from sandy soils and hence reduce algal blooms in our waterways.

Promotional Poster after Successful Field Trials of Iron Man Gypsum™

Carbon fines are also stored in lined dams. Recent development work at Iluka has established a process to upgrade the carbon fines to an activated carbon that can be used to remove metal and organic residues from industrial and municipal flue gasses.