Mineral-Sands

Mineral sands containing titanium-dioxide minerals are used as pigment for paint. Where zircon is present it is used in ceramics such as sanitary basins and tiles. The minerals contained in mineral sands would have originated as crystals in igneous rocks such as basalt, pegmatite and granite, or in some cases, metamorphic rocks.

Weathering Over Millions of Years Eventually Creates Mineral Sand
Over a period of millions of years these rocks would become eroded away through weathering with the grains of quartz and other minerals being washed into the sea by fast flowing streams following heavy rainfall. Waves eventually wash the minerals up onto the beach where they continue to be broken down with the continual washing action of the waves rolling in and retreating. This continuous motion eventually leaves the heavier minerals on the beach, these being; monazite, rutile, ilmenite and zircon. Wind, that is commonplace on exposed beaches, blows away the lighter quartz particles and eventually only the heavier mineral sands are left. This creates a deposit of highly valued mineral sands.

Moving Shoreline can Leave Deposits of Mineral Sands far Inland
Sea levels rising and falling over time meant the shoreline was never permanent having at one time been further inland and then retreating to where it is today. As this occurred deposits of mineral sands were left behind only to become buried by more sand being blown in and on occasions being re-deposited somewhere else. This is why some mineral sand deposits are located many kilometres from the sea and sometimes up to 50 metres below the present day surface.

Mineral Sands Mined via a Dry or Wet Method
Because of the varying deposits of mineral sands, mining involves dry and wet operations. Wet mining being dredge mining. In some countries mineral sand mining is carried out in a similar fashion as hard rock mining but in Australia it is mostly restricted to wet (dredging), or dry mining techniques:
• Dry mineral sands mining requires the use of scrapers, excavators and trucks. Dozers, or loaders are used to move the mineral sand to a processing, or washing plant. This type of mining mineral sands is suitable when shallow, hard bands of mineral sands deposits require mining, or when a series of unconnected ore bodies are encountered.
• Dredge mining, otherwise known as wet mining, is used when the mineral sand ore deposit is below the water table. The mineral sand is pumped from the bottom in the form of a slurry to a concentrator floating on a nearby barge. The slurry is washed through spirals using gravity to separate the heavier mineral sands from the clay or quartz that is much lighter.

Minerals Separated in a dry Processing Circuit
Heavy minerals such as monazite, zircon, leucoxene, rutile and ilmenite are separated in a dry processing circuit that uses electrostatic, density and magnetic characteristics. Zircon to be used in the ceramic industry requires further purification by means of an acid wash in order to remove coatings of iron oxide.