Synthetic rutile is a chemically modified form of ilmenite which has had most of the iron removed. The product’s composition is between 85 and 95 per cent titanium dioxide (TiO2). The upgraded TiO2 products are similar to naturally formed rutile.
Ilmenite, an iron/titanium oxide mineral, can be upgraded to synthetic rutile (or upgraded ilmenite) containing between 85 and 95 per cent highly valued titanium dioxide. Iluka has four synthetic rutile kilns with a combined capacity of 500 – 550 thousand tonnes per annum.The ilmenite used in the process generally has between 57 and 60 per cent TiO2 and yields about 0.6 tonnes of SR for
every tonne of ilmenite used.
The main objective of the process is to remove the iron component of the ilmenite by reducing it to metal and “leaching” it to leave an upgraded titania product. This process is known as the Becher Process, after its inventor, Dr Robert Becher, who developed the process in Western Australia in 1961. The process was commercialised by Iluka’s predecessor company, RGC, in 1969
Synthetic Rutile Products
A number of SR products can be made in the process, depending on the quality of the ilmenite used in the process and the various additional processing steps utilised.
In the Standard SR process, the synthetic rutile, after aeration, is filtered and dried, and is ready for sale and produces a synthetic rutile of 85 per cent to 88 per cent TiO2 grade. In the Premium SR process, the synthetic rutile is upgraded by leaching with diluted sulphuric acid to remove the iron and manganese phases resulting from sulphur addition to the reduction process and produces a synthetic rutile of 91 per cent to 93 per cent TiO2 grade. Sulphur addition is made only in the Premium SR process. The sulphur improves iron and manganese removal in the downstream process by reacting in the kiln with the manganese, and stopping the stabilisation of irreducible iron/titanium compounds. After filtering and drying the Premium SR is ready for sale.
- In the SREP process, a boron flux is added to the mineral in the kiln to form a glassy phase on the mineral surface which extracts trace contaminants from the minerals. Post aeration, stages of acid and caustic scrubbing remove the glassy phase and the resulting synthetic rutile contains 94 to 95 per cent TiO2 Overall TiO2 recovery from ilmenite in the SR process is around 95 per cent.
SR FLOW DIAGRAM