Extraction of iron from titaniferous ores

Claim 2

Method for leaching the iron from finely divided ilmenite ores to produce a titanium dioxide concentrate according to claim 1 wherein the oxidiZing agent is ferric chloride.

Claim 3

Method for leaching the iron from finely divided ilmenite ores to produce a titanium dioxide concentrate according to claim 1 wherein the oxidizing agent is nitric acid.

Claim 4

Method for leaching the iron from finely divided ilmenite ores to produce a titanium dioxide concentrate according to claim 1 wherein said oxidizing leach is effected by introducing air or oxygen into the dilute sulfuric acid leach solution.

Claim 5

Method for leaching the iron from ilmenite ores to produce a titanium dioxide concentrate according to claim 5 wherein the oxidizing leach is accelerated by the addition of gaseous SO2.

Claim 6

Method for leaching the iron from finely divided ilmenite ores to produce a titanium dioxide concentrate according to claim 1 wherein the partially leached ore produced by said acid leach is filtered and washed prior to said oxidizing leach.

Claim 7

Method for leaching iron from finely divided titaniferous ores according to claim 1, wherein leaching with said dilute sulfuric acid is carried out for from 5 to 15 minutes and leaching with said oxidizing agent is carried out for 5 to 8 minutes.

Claim 8

Method for leaching the iron from finely divided ilmenite ores according to claim 1 wherein the dilute sulfuric acid is waste sulfuric acid having an acid strength within the range from 3 to 24% H2SO4 and said waste sulfuric acid being used in an amount corresponding to an acid to total iron ratio in the range from 1:1 to about 3:1.

Claim 9

Method for leaching the iron from finely divided ilmenite ores to produce a titanium dioxide concentrate according to claim 1 wherein the finely divided ore is roasted in an oxidizing atmosphere prior to reducing the iron values to metallic iron.

Claim 10

Method for leaching the iron from finely divided ilmenite ores to produce a titanium dioxide concentrate comprising the steps of: upgrading the finely divided ore by removing gangue materials, heating the gangue-free ore under reducing conditions to reduce the iron values in said ore to metallic iron, leaching the metallized ore with waste sulfuric acid at a concentration in the range of from 5 to 15% H2SO4, at an acid pH, and at a temperature from 25*-100* C. for a period of time from 5- 15 minutes to dissolve a major portion of the metallized iron from said ore, said waste sulfuric acid being added in an amount corresponding to an acid to total iron ratio of about 3:1, and thereafter leaching the acid leached ore with an oxidizing leach comprising an aqueous solution of a water-soluble ferric salt, said salt being added to said acid leach solution in an amount corresponding to a ferric salt to total iron ratio of from about 0.25:1 to 1:1, and at a temperature of from 25* to 100* C. for from 5 to 8 minutes to dissolve the remaining metallized iron from said ore, recovering the leached ore by filtration, and then water-washing the leached ore.