Process to obtain titanium concentrates with high contents of TiO

1. A process to obtain titanium concentrates with high contents of TiO 2 and low contents of radionuclide elements from anatase mechanical concentrates, said process comprising the steps of:

(a) calcinating ore in a fluidized bed or rotary kiln in a temperature range of 400° C. to 550° C. for 30 minutes to one hour, converting hydrated iron oxides into hematite and reducing time necessary for a next reduction step, to form a calcinated product;

(b) conducting reduction of the calcinated product in the fluidized bed or rotary kiln at 400° C. to 550° C. for 5 to 30 minutes, using hydrogen, carbon monoxide, natural gas or any other reducing gas to convert hematite into magnetite, to form a reduced product having a first magnetic fraction;

(c) conducting low-intensity magnetic separation of the reduced product in drum separators in a 600 to 800 Gauss magnetic field, thereby extracting the first magnetic fraction formed in the reduction stage, to form a low-intensity non-magnetic fraction;

(d) conducting a dry, high-intensity magnetic separation of the low-intensity non-magnetic fraction in a drum or roll separator and a rare-earth permanent magnet in a 16000 to 20000 Gauss magnetic field, thereby extracting a second magnetic fraction from silicates, secondary phosphates, monazite, calzirtite, zirconolite and uranium and thorium bearing minerals, to form a high-intensity magnetic fraction;

(e) conducting hydrochloric acid leaching of the high-intensity magnetic fraction, in agitation or column tanks, with 20 to 30% w/w HCl, in a 1/2 w/w solid-liquid ratio at a temperature between 90° C. and 107° C. for 2 to 4 hours, thereby solubilizing primary phosphates, iron oxides, aluminium, magnesium, barium and calcium, to form a leached product;

(f) conducting filtration of the leached product in a belt filter, to form a first filtrated product;

(g) drying of the first filtrated product in a rotary or fluidized-bed drier, to form a first dried product;

(h) oxidizing of the first dried product in a rotary kiln or fluidized bed reactor, under a flow of air or oxygen at a temperature range of 1000° C. to 1100° C. in a presence of a mixture of sodium fluoride (NaF) and amorphous silica (SiO 2 ), in a 3% to 10% NaF and 1% to 10% SiO 2 proportion with respect to an amount of material fed to oxidation, thereby forming in a boundary of anatase grains a radionuclide-rich vitreous phase in addition to promoting radionuclide migration to an iron-rich phase, to form an oxidation product;

(i) quenching the oxidation product in water, thereby respectively stabilizing the vitreous and the iron-rich phases, to form a first quenched product;

(j) conducting hydrochloric acid leaching of the first quenched product in agitation or column tanks with 20 to 30% w/w HCl with in a 1/2 w/w solid-liquid ratio at a 90° C. to 107° C. temperature range for 2 to 4 hours, in a presence of sodium fluoride (NaF) or hydrofluoric acid (HF), thereby solubilizing a radionuclide-rich vitreous phase through generated or added fluoride ion (F − ) action, to form a second leached product;

(k) filtering of the second leached product in a belt filter, to form a second filtrated product;

(l) drying of the second filtrated product in a rotary or fluidized bed drier, to form a second dried product;

(m) conducting dry, high-intensity magnetic separation of the second dried product in a 16000 to 20000 Gauss magnetic field in a drum or roll separator and rare-earth permanent magnet, thereby separating an iron containing, radionuclide rich magnetic fraction from a non-magnetic fraction, the non-magnetic fraction becoming the end product concentrate and the iron containing, radionuclide rich magnetic fraction being discarded.

2. The process according to claim 1 , wherein the reduction in step (b) is carried out at 500° C. for 5 minutes.

3. The process according to claim 1 , wherein the magnetic field used in the dry, high intensity magnetic separation in step (d) forming the high-intensity magnetic fraction is 20000 Gauss magnetic field.

4. The process according to claim 1 , wherein the hydrochloric acid leaching in step (e) is carried out using a solution containing 20% to 25% w/w HCl for 4 hours at a temperature of 150° C.

5. The process according to claim 1 , wherein the oxidation in step (h) is carried out in a rotary horizontal kiln or in a fluidized bed with 6% to 7% NaF and 3% to 4% SiO 2 with respect to an amount of material fed to oxidation, under continuous air or oxygen injection, for a duration of 30 to 120 minutes.

6. The process according to claim 1 , wherein the hydrochloric acid leaching in step (j) is carried out with a solution containing 25% w/w HCl for 4 hours at a temperature of 105° C. and in the presence of sodium fluoride or hydrofluoric acid, with an amount ranging from 10 g to 30 g of fluoride ion (F − ) per liter of leaching solution.

7. The process according to claim 1 , wherein the magnetic field used in the dry, high-intensity magnetic separation of the second dried product in step (m) is a 20000 Gauss magnetic field.