Satellite elevation data of the Murray Basin, shown in blue-green colours, in southeastern Australia. Source: Geoscience Australia. Rutile and ilmenite originally grew as crystals in igneous rocks such as granite, pegmatite and basalt and some metamorphic rocks.
Over millions of years, these rocks were weathered and eroded forming small grains of quartz and other minerals including rutile and ilmenite. These grains were washed down to the sea by heavy rainfall and fast flowing streams and became part of the coastal sands.
The relative density of common sand minerals such as quartz is around 2. As waves washed up and down on the beach they carried the lighter quartz grains with them back out to sea, leaving the grains of the heavy minerals on the beach. Wind also helped to concentrate the heavy minerals by blowing away the lighter quartz sand. Repeated many times over millions of years, these processes eventually created large deposits of mineral sands. Heavy mineral layers dark in a quartz beach sand Chennai, India.
As the sea level fell and rose over geological time, the shoreline moved further inland and then back again. As this happened, the deposits of mineral sand were covered by more sediment and built up or were eroded and redeposited elsewhere. This is why we sometimes find mineral sand deposits many kilometres inland and as much as 50 metres below the surface.
Rutile and ilmenite are found in mineral sand deposits associated with modern and ancient beaches and dunes on the east, west and southern coastlines of Australia.
In Western Australia, deposits are distributed from the southern tip of the state to Geraldton and are located at the present coastline or as relic deposits up to 35 km inland. Australia's major titanium from rutile and ilmenite deposits and mines Australia is rich in mineral sand resources but, because they are mainly located at or near the coast, their mining competes with other land uses such as agriculture, national parks, urban or tourist development and recreation.
Allocation of land to other uses has rendered some mineral sands resources inaccessible to exploration or mining. Throughout the late s, a large number of coarse-grained strandlines were identified in the Murray Basin, which occurs within New South Wales, Victoria and South Australia. Over million tonnes of heavy mineral sand concentrates were outlined.
Large resources of fine-grained mineral sands deposits referred to as WIM-type deposits occur in the Horsham region of Victoria. Further resource and production information.
Although mineral sand deposits were noticed back in , sands were first mined in Australia in the s at Byron Bay on the north coast of New South Wales.
Mining of ilmenite began in the mids near Bunbury in southwest Western Australia. Today, Western Australia is the largest producer. To mine these minerals, sands are dredged through a large suction pipe and the heavy minerals are separated from the lighter sand particles. As the dredge moves slowly forward, the clean sand tailings are pumped back to fill the mined area. Some higher-grade deposits containing moderately hardened material or layers are mined using equipment such as self-loading scrapers, bucket-wheel excavators, bulldozers and front-end loaders.
Careful environmental rehabilitation of mined areas is carried out progressively as the dredge moves forward. It is found in both oxide and silicate minerals. In such low concentrations it is not economical to extract. Titanium can be mined from intrusive crystalline rocks, weathered rock and unconsolidated sediment. Half of all Titanium mined comes from unconsolidated sediments known as shoreline placer deposits.
Placers are alluvial deposits formed by rivers as they reach the sea. Suspended sediments have different densities known as specific gravities. A river will deposit different sediments as its speed fluctuates, forming separate layers of sediment. Rutile has traditionally been the primary input in the manufacture of Titanium metal. Its name comes from the Latin rutilus meaning red. Its deep red colour is caused by iron impurities in its lattice.
Rutile is formed under high pressures and temperatures as an accessory mineral in metamorphic rocks like eclogite. It is not economical to mine rutile from primary rock so it is recovered from weathered deposits in mineral sands. Important sites include Gbangbama, Rotifunk, Sembehun and Kambia. The ore ilmenite is much more abundant than rutile. It is formed in magma chambers in intrusive rocks like nortite, anothosite and gabbro.
Extracting the Titanium Most titanium mining is done by open pit, meaning that the soil is taken from the ground and sent to factories where the ore can be removed. This process is usually done with a suction bucket wheel on a floating dredge. Mineral-rich sand is sent through its screens, called trammels, which starts filtering out the unwanted or unnecessary elements. The separation is usually gravity powered, and the waste can be removed with a wet spiral concentrator.
At this point, the separated material can be sent through some electrostatic, magnetic, and other gravity-fed equipment to further refine the materials into something useful. Processing the Material. So far, this process is not too far removed from other mining and extraction operations. However, this is where things get a little more difficult.
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