Before refining uranium, it is necessary to separate the uranium itself from the gangue that contains it. This work is carried out on the site or in a mill near the site, using one or two of the procedures described below.

The ore is treated where it is found, directly by means of injection wells in permeable mineralized formations or by washing out old mines. The latter method has been applied in France, notably at the site of Le Brugeaud (Haute-Vienne). According to the nature of the ground, sulfuric acid or sulfur is used.

The raw ore is placed in a big pile and watered with an acid or alkaline solution. The solution, which picks up a little uranium, is recovered and recycled for use in rewatering the same pile. Slow leaching was used at La Commanderie (Vendée and Deux-Sèvres) and Saint-Hippolyte (Vosges) among other sites.

The mineral is ground (to about 25 mm), placed in covered basins, and attacked by an acid solution. Le Cellier (Lozère) used accelerated leaching.

The solution was carried to a treatment plant and the solids remain in place. These procedures are applied to ore that is poor or very poor in uranium.

Leaching in submerged stalls. The mineral is broken up, ground, and attacked by cold acid (leaching). The uranium is fixed on ion exchange resins stored in containers. The resins are then carried to a treatment plant. The level of uranium in the transported product—the preconcentrates—is almost ten times that of the treated ore. Such installations were found at La Ribière (Creuse) and at Bertholène (Aveyron).

The mineral is broken up more finely (0.5 to 0.1 mm) and mixed with water. Then it is attacked either by warm sulfuric acid or by an alkaline treatment. On filters the liquid part (a uranium solution) is separated from the solid part (treatment residues known as taillings). The uranium-bearing solution is then purified. The procedures used in France produced magnesium uranate, ammonium diuranate or sulfur uranate or a solution of uranyl nitrate.

No milling plants are in operation in France today.  The last to operate, at Jouac (Haute-Vienne), ceased production in 2001.  Other now-closed plants that carried out the entire treatment were Bessines (Haute-Vienne), Le Bosc/Lodève (Hérault), L’Ecarpière (Loire-Atlantique), Guegnon (Sane-et-Loire), Le Cellier (Lozère), Saint-Pierre (Cantal), and Saint-Priest (Loire).

Because of the numerous sites, we will treat wastes from the concentration installations here.

These installations release radioactive and non-radioactive (acid) gaseous effluents from the factory and from the tailings deposits (below).

These effluents are composed of water from the laundry, drainage from the ore and tailings storage areas (below), and from the plant itself. The water from the plant may contain radium. Treatment of water from the plants is similar to that of water from the mines, and, in the case of a plant associated with a mine, the waters are often treated together. The solid residues from the factory are often mixed and treated with the liquid effluents and sent in the form of pulp to an area for spreading, where the solids are decanted and from which the liquids are evacuated.

The primary wastes are::

--sludges from decantation and precipitation, including radium sulfate;

--tailings containing 5 to 10% of the uranium in the original ore; the descendents of uranium 235 and 238, alpha, beta, and gamma emitters; the major part of the metals and sulfates in the original ore; and the residues from the chemical reagents used during treatment of the ore, particularly sulfuric acid and hydrocarbon residues.

The problems posed by the tailings are of several types:

--release of gamma radiation, which can reach at the surface of the deposit 20 to 100 times the natural radioactivity of the site [Diehl 95];

--permanent giving off of radon;

--the dissemination of radioactive dusts (in the case of the surface deposit’s drying up);

--pollution from surface and underground water, because of the dilution of the radionuclides, metals and sulfurs by water that has infiltrated the deposit;

--the permanent release of radon;

--the dissemination of radioactive dusts (in case of the drying of the surface of the deposit);

--the pollution of surface and underground waters, because of the dilution of the radionuclides, metals and sulfurs by water infiltrating the deposit;

--the possibility of rupture of a dike;

--use of tailings as materials for construction or for public works.

The weight of the dry residues is roughly equivalent to that of the treated ore. The residues are very fine and very wet and constitute a sort of mud. In France, the stock of residues is estimated to amount to more than 50 million tons [InfoU xi-xii 93].

The deposits come under either the regulations for basic nuclear installations (INBs) or the legislation on installations classed for the protection of the environment (IC). Decree no. 66-450 of 6 June 1966 classifies radioactive substances into three groups. A site containing radioactive substances belonging to several groups is an INB if the total radioactivity of all the radioactive substances is equal to or greater than 10000 Ci (37 TBq). The tailings deposits contain radioelements belonging to three groups. To simplify we can thus say that a tailings deposit should be an INB when the sum of the radioactivity of the thorium 230 and of the radium 226 contained in the residues exceeds 1000 Ci (37 TBq).

The declaration or authorization regulations do not apply to solid, natural radioactive substances, the mass activity of which is less than 500 Bq/g. The mining companies and the administration avoid applying the strict declaration or authorization regulations for INBs, by arguing that residue deposits contain only natural uranium, which is not true, given the fact that the uranium has been brought to the surface and subjected to physical and chemical treatment.

In a new classification of wastes that DSIN has proposed, mine tailings belong to the category "very weak activity and long life." DSIN foresees leaving the wastes at the mines where they are now located but improving the conditions under which they are stored [DSIN 98].