A process for enrichment of anatase mechanical concentrates in order to obtain synthetic rutile with low contents of rare earth and radioactive elements

摘要

A process for obtaining synthetic rutile with low contents of rare earth and radioactive elementsfrom anatase mechanical concentrates, comprising the following sequential operations:calcination (1) of the anatase concentrate in a fluidized bed or rotary kiln whereinhydrated iron oxides are converted into hematite after hydration water is removed,providing a reduction in the time required for next step; reduction (2) of thecalcined product, in a fluidized bed or rotary kiln, using hydrogen, naturalgas or any carbon based reducing agent such as metallurgical coke, charcoal, petroleumcoke, graphite, among others, the result of which is the transformation of 15allurgical coke, charcoal, petroleum coke, graphite, among others, the resultof which is the transformation of hematite into magnetite; dry or wet low-intensity magneticseparation (3) of the reduced product, high-intensity, high-gradient magneticseparation (4) of the low-intensity non-magnetic fraction, extracting silicates,secondary phosphates, monazite, calzirtite, zircolinite and uranium and thorium-containingminerals; leaching (5) of the magnetic fraction of the high-intensity, high-gradientseparation in agitated tanks or fluidized bed columns, with a solution providingsolubilization of impurities rich in iron, aluminium, phosphates, magnesium,barium, calcium, strontium, rare earths, uranium and thorium; filtering ofthe leached product drying of the filtered product oxidation (6) of the driedproduct in the presence of a mixture of the following substances, alkali, metalsulphates (mainly lithium, sodium and potassium), alkali metal carbonates(mainly lithium, sodium and potassium), phosphoric acid (H3PO4) and, eventually,sodium chroride; quenching of the oxidized product in water or compressed air;leaching (7) of the queched product in agitated tanks or colums, filtering ofthe product from the second leaching (7) in a belt filter; and drying of the filteredproduct in a rotary or fluidized bed drier, dry, high-intensity, high-gradientmagnetic separation (8) of the product of the second leaching, in rare-earthpermanent magnet, discarding of the magnetic fraction and recovering the non-magneticfraction as final product (P), that is, the synthetic rutile of interest.