The main by-product source of uranium today is at Olympic Dam in South Australia, where low concentrations of uranium (0.025 to 0.050%U) occur with copper grading about 1.8%Cu. Present production there is about 3500 tonnes of uranium, but there are plans to increase annually this to 16 000 tU/yr.

Following primary crushing underground, the ore is ground and treated in a copper sulfide flotation plant. About 80% of the uranium minerals remain in the tailings from the flotation cells, from which they are recovered by acid leaching as in a normal uranium mill. The copper concentrate is also processed through an acid leach to recover much of the other 20% of the uranium. The pregnant liquor is then separated from the barren tailings and in the solvent extraction plant the uranium is removed using kerosene with an amine as a solvent. The solvent is then stripped, using an ammonium sulfate solution and injected gaseous ammonia. Ammonium diuranate is then precipitated from the loaded strip solution by raising the pH, and removed by centrifuge. In a furnace the diuranate is converted to uranium oxide product.

However, after the secondary recovery by acid leaching, some uranium remains in the copper concentrate as it proceeds to be smelted. Typically it would have 45% Cu and up to 0.15% uranium, and the uranium is recovered in the further copper processing. This creates a safeguards problem if the smelting and electro­refining is not done at the mine site.

In the past some uranium has been recovered as a by-product of phosphate production, and this is set to be revived, with new technology, on an increased scale. Phosphate rock (phosphorite) is a marine sedimentary rock, which contains 18-40% P2O5 , as well as some uranium and all its decay products, often 70 to 200 ppmU, and sometimes up to 800 ppm. The phosphate rock is treated with sulfuric acid to give gypsum and phosphoric acid, and the uranium is normally recovered from the phosphoric acid by some form of solvent extraction (SX). A new process — PhosEnergy — uses ion exchange (IX) and promises to reduce recovery costs significantly.

The potential amount of uranium able to be recovered from phosphoric acid streams is over 11 000 tonnes U per year (global P2O5 production in 2010 was 33.6 Mt). The economic benefit will be both in the value of the uranium and in reduced regulatory demands on disposal of low-level radioactive wastes arising from the process. Estimated uranium production costs will put the new process in the lowest quartile of new uranium production.

6.2 World uranium production and demand.