Radium sludge

The most common isotope of protactinium is Pa (tj/2 = 3.3 x 10 years), which occurs in pitchblende in the amount of 300 mg/ton, about the same as radium. The heroic efforts of British researchers resulted in the isolation of some hundred grams of Pa from the sludge left over from uranium processing without this supply, little or nothing would... 

The metals of most concern are the heavy metals, especially cadmium, lead, and mercury. Although it is a metalloid with characteristics of both metals and nonmetals, arsenic is commonly classified as a heavy metal for a discussion of its toxicity. Though not particularly toxic, zinc is abundant and may reach toxic levels in some cases. For example, zinc accumulates in sewage sludge and crop productivity has been lowered on land fertilized with sludge because of zinc accumulation. Copper may be toxic to plants. Aluminum, a natural constituent of soil, may be leached from soil by polluted acidic rainwater and reach levels that are toxic to plants. Other metals that may be of concern because of their toxicides include chromium, cobalt, iron, nickel, and vanadium. Radium, a radioactive alpha particle-emitting metal, can be very toxic at even very low levels in water or food. 

Paul, A.C., Pillai, P.M.B., Komalan Nair, S. and Pillai, K.C., Studies on the leaching of Radium and the emanation of Radon from fertilizer process sludge. J. Environ. Radioact. 1 (1984) 51-65. 

Radium in the monazite may be removed with the sludge by adding barium carbonate before decantation. This forms barium sulfate, which removes radium as insoluble radium sulfate. 

The alkaline process is less common than the acid process and provides lower recovery rates of uranium. For both processes, the ore must be first reduced to a size smaller than 75 p.m (mesh 200). Important radioactive pollutants from either process are Ra (radium 226) and Rn (radon 222). By adding barium chloride in settling ponds or lagoons, radium is treated. Radium-containing slurries and sludges are the subject of extensive research. Radium 226 decays to form radon gas from the tailings and is dangerous to health. 

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