Simplified Schematic Mill Flowsheet

Fines _

Atmosphere

Demister

Clarified fil Clarification

[~6~| SolventExtraction

FIG. 11.25.1 Process schematic for a typical uranium mill.

Clarified fil Clarification

[~6~| SolventExtraction

FIG. 11.25.1 Process schematic for a typical uranium mill.

and bismuth. Tailings and waste produced from the extraction or concentration of uranium or thorium from any ore processed primarily to recover source material is called by-product material. Source material is defined as any material containing more than 0.05% uranium and/or thorium by weight. Exemptions from most NRC regulations exist for many commercial uses of source material. Byproduct material is regulated as radioactive waste, including surface wastes from uranium solution extraction. Underground ore bodies depleted by such techniques are not considered by-product material.

Proper handling and disposal of waste classified as byproduct material is a large part of any mining and milling operation (IAEA 1976). The typical process produces waste at almost every step. Most wastes are put into tailings ponds where uranium is periodically recovered. These ponds are normally highly acidic due to the large quantities of acid used in the ore leaching step. They may also be contaminated with organic solvents or ion exchange resins if these are used in the recovery step. Many of these impoundments have contaminated local groundwaters (UNSCEAR 1977). Treatments for runoff from uranium mills have been developed; a typical treatment process is shown in Figure 11.25.2. This process is designed to produce an effluent that comes close to meeting the drinking water limits of 5 pCi/L total radium and 3 pCi/L of radium 226. The concentrated radioactive (radium) sludge (Tsivoglou & O'Connell 1965) is then handled as a low-level radioactive waste.

Tailings ponds, even after closure, are a constant source of radon from the decay of radium. Tailings are sometimes used as building materials, posing a potential health hazard from radon seepage.

Non-radioactive mining such as phosphate rock operations can produce tailings containing uranium, thorium, and radium at levels above those permissible for release to the environment. These tailings also often find their way into commerce as building materials.

Sludge to Disposal at a LLWD Site

FIG. 11.25.2 Process schematic of a typical radium removal operation.

Sludge to Disposal at a LLWD Site

FIG. 11.25.2 Process schematic of a typical radium removal operation.

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