Process for the production of titanium dioxide from anatase ore through sulphuric acid digestion, followed by leaching, hydrolysis, and calcination

Patent metadata

Field	Value
Publication number	US-2023373809-A1
Application number	US-202118030632-A
Country	US
Kind code	A1
Filing date	Oct 6, 2021
Priority date	Oct 6, 2020
Publication date	Nov 23, 2023
Grant date	—

Abstract

Processes to solubilize the titanium and, later, hydrolyze it as titanium dioxide, in part based on the mineral ogical complexity of the anatase ore. The process described is capable of sufficiently solubilizing titanium in anatase using H2SO4, while overcoming the low reactivity of the ore to this acid. Moreover, the process does not require a reduction step prior to anatase digestion.

First claim

1 . A method of producing titanium dioxide concentrate from anatase or, the method comprising:
subjecting anatase ore particles to sulphuric acid to digest the anatase ore particles thereby forming digested ore; leaching the digested ore with water thereby forming leached ore; filtering the leached ore to produce a filtrate and a residue; subjecting the filtrate to hydrolysis to form a precipitate; and subjecting the precipitate to calcination, thereby forming titanium dioxide (TiO 2 ).

2 . The method of claim 1 , wherein the digestion step takes place in conditions such that a solubilization of titanium dioxide in the form of titanyl sulfate, TiOSO 4 , occurs, according to the reaction: TiO 2 +H 2 SO 4 →TiOSO 4 +H 2 O.

3 . The method of claim 2 , wherein the sulphuric acid has a concentration of at least 98%, the ratio of ore particles to sulphuric acid is 1:2, or both.

4 . The method of claim 2 , wherein a reaction temperature of the digestion step is in a range of about 180° C. to about 240° C., a reaction time is in a range of about 3 to about 6 hours, or both.

5 . The method of claim 1 , wherein the ore particles have an ore grain size of 99% less than 62 μm.

6 . The method of claim 1 , further comprising:
classifying raw anatase ore particles by grain size into a first portion and a second portion; discarding the first portion; and subjecting the second portion to a first grinding step until about 60% of the second portion has an ore grain size of less than 210 μm.

7 . The method of claim 6 , further comprising, after the first grinding step:
subjecting the second portion to a magnetic separation step to remove iron oxides from the second portion such that a reduction step is not required.

8 . The method of claim 7 , wherein the magnetic separation step comprises, in order:
subjecting the second portion to a first magnetic field; subjecting the second portion to a second magnetic field greater than the first magnetic field; and subjecting the second portion to a third magnetic field greater than the second magnetic field.

9 . The method of claim 8 , wherein the first magnetic field is in a range of from about 1,000 Gauss to about 2,000 Gauss, wherein the second magnetic field is in a range of from about 6,000 Gauss to about 8,000 Gauss, and wherein the third magnetic field is in a range of from about 11,000 Gauss to about 15,000 Gauss.

10 . The method of claim 7 , wherein, after the magnetic separation step, the second portion is subjected to a second grinding step until about 99% or more of the second portion has an ore grain size of less than 62 μm.

11 . The method of claim 1 , wherein the leaching step is carried out at a solid:liquid ratio of 1:4.

12 . The method of claim 1 , wherein the leaching step is carried out at a temperature in a range between 50° C. and 70° C., with mechanical agitation, for a period between about 2 and about 4 hours.

13 . The method of claim 1 , wherein the filtrate is rich in titanium.

14 . The method of claim 1 , wherein the hydrolysis step is carried out in a filtrate:water ratio of 1:5.

15 . The method of claim 1 , wherein the hydrolysis step comprises:
heating each the filtrate and water are heated separately to a temperature in the range of from about 50° C. to about 75° C.; subsequently mixing the filtrate and water; heating the mixed filtrate and water to a temperature in the range of from about 80° C. to about 105° C.; and maintaining, by stirring and heating, the mixed filtrate and water for a period of time in a range of from about 2 hours and about 5 hours.

16 . The method of claim 1 , wherein, during the hydrolysis step, hydrated titanium dioxide precipitates out of solution as the precipitate based on the reaction:
TiOSO 4 +2H 2 O→TiO(OH) 2 +H 2 SO 4

17 . The method of claim 16 , wherein the precipitate is filtered out of solution and washed with water to obtain TiO 2 ·nH 2 O.

18 . The method of claim 1 , wherein the calcination step is carried out at a temperature in a range of from about 900° C. to about 1100° C., and for a period of time in a range of from about 1 hour to about 4 hours.

19 . The method of claim 18 , wherein the calcination step thermally decomposes TiO(OH) 2 to TiO 2 .

20 . The method of claim 1 , wherein the method does not include a reduction step for removing iron oxides prior to anatase digestion.

21 . A titanium dioxide product formed from the method of claim 1 .

Assignees

• Mosaic Co
• Companhia De Desenvolvimento De Minas Gerais Codemage S/A

Inventors

• Ladeira Ana Cláudia Queiroz
• Da Castro João Batista
• Brandão Rafael Nogueira
• Costa Lílian Lís De Andrade Cantuário

Classifications

• C01G23/0532 Primary

  by hydrolysing sulfate-containing salts · CPC title

• C01G23/08 Primary

  Drying; Calcining {; After treatment of titanium oxide} · CPC title

• C01P2006/80

  Compositional purity · CPC title

• C01G23/008

  Titanium- and titanyl sulfate (C01G23/001 takes precedence) · CPC title

• C22B34/1213

  by wet processes, e.g. using leaching methods or flotation techniques · CPC title