leaching of titaniferous materials

In a process for removing one or more radionuclides and daughters thereof from titaniferous material, said material

• (i) being an aerated product or a synthetic rutile, and
• (ii) containing the radionuclides and in a phase which is highly soluble in acid, said phase being formed by contacting the titaniferous material at an elevated temperature with one or more reagents selected to form the phase at the elevated temperature, and which phase disperses onto the surfaces of the titaniferous material and incorporates the radionuclides and daughters thereof,
• the process comprising leaching said material in a step-wise manner with sulphuric acid solution and with hydrochloric acid solution in either order, the improvement wherein the hydrochloric acid leach is enhanced for removal of one or more of said daughters by pre-treatment of said material with a solution of an effective amount of an alkaline metal hydroxide at a concentration no greater than about 0.1M, the temperature in the range ambient to about 80.degree. C., and a pressure in the range from about 1 to about 5 atmospheres.

In a process for removing one or more radionuclide decay products from titaniferous material, said material

• (i) being an aerated product or synthetic rutile, and
• (ii) containing said radionuclide decay products in a form which is highly soluble in acid,
• the process comprising leaching said material in a step-wise manner, with sulphuric acid solution and with hydrochloric acid solution, the improvement wherein the hydrochloric acid leach is augmented by pre-treatment of said material with a solution of an effective amount of a hydroxide thereby to modify, and facilitate removal by hydrochloric acid leaching of, sulphate salts of the decay products, which salts are formed during the sulphuric acid leach.

In a process for removing radium from titaniferous material, said material

• (i) being an aerated product or synthetic rutile, and
• (ii) containing said radium in a form which is highly soluble in acid,
• the process comprising leaching said material in a step-wise manner with sulphuric acid solution and with hydrochloric acid solution, the improvement wherein the hydrochloric acid leach is augmented by pre-treatment of said material with a solution of an effective amount of a hydroxide thereby to modify, and facilitate removal by hydrochloric acid leaching of, radium sulphate salts formed during the sulphuric acid leach.