Patent ID: 7572418
Filing Date: 2009-08-11
Classification: C01G,C22B,Y02P

Abstract:
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 (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 (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.