Radium Purification

Figure 1. Schematic diagram showing a TRU-spec extraction chromatography method for separation of uranium, thorium, protactinium, and radium from a single rock aliquot. Further purification for each element is normally necessary for mass spectrometric analysis. Analysis of a single aliquot reduces sample size requirements and facilitates evaluation of uranium-series dating concordance for volcanic rocks and carbonates. For TIMS work where ionization is negatively influenced by the presence of residual extractant, inert beads are used to help remove dissolved extractant from the eluant.

In some cases, technology helps to reduce the natural radiation exposure. For example, when drinking water supplies are drawn from surface waters, the use of water-purification processes brings about a decrease in the concentration of radium and other naturally occurring radioactive elements. Another example is the burning of fossil fuel, which reduces the specific activity of C in the biosphere and therefore lowers the doses from those radionuclides. 

But they were not finished with their research. They thought at least one other element might be in the pitchblende. So they continued the process of purification. In 1898, they isolated a second new element. They called this element radium. They chose this name because the element gives off such intense radiation. It took the Curies another four years to prepare one gram of... 

Becquerel s student Marie Sklodowska Curie (1867-1934) and her husband, Pierre Curie (1859-1906), began to investigate this new phenomenon and were aided in their examination of the elements for radioactivity by the loan of some rare elements such as thorium. Only uranium and thorium seemed to have this property, but this led them to investigate the components of the mineral pitchblende. Pitchblende was composed primarily of uranium oxide, but the results of the ionization tests seemed to indicate that it had was more ionizing power than could be accounted for by uranium alone. After months of purification and separation work, in July 1898 they announced the discovery of polonium, named after Poland, Marie Curie s homeland. By December, further work led to the discovery of a second new element, which they named radium. The Curies, along with Becquerel, were awarded the Nobel Prize for... 

Derivation Uranium ores (pitchblende and camo-tite). The method used for isolating radium is similar to that developed by Mme. Curie and involves coprecipitation with barium and lead, chemical separation with hydrochloric acid, and further purification by repeated fractional crystallization. The metal is separated from its salts by electrolysis and subsequent distillation in hydrogen. Dry salts are stored in sealed glass tubes, opened regularly by experienced workers to relieve pressure. The tubes are kept in lead containers. 

Purification. - The extraction met hods yield a mixture of radium ami barium chlorides or sulfates. If sulfates are ols-tained, they an- reduced to the sulfides by mixing with charcoal and heating to about K00 or changed to earln.nates by boiling with N a( < ).i. 

Virtually all of the Canadian mills have used a variant of the acid-leaching process developed by the Mines Branch to extract uranium fiiom the ore, and all but Port Radium have followed this by ion-exchange purification of the leach solution with strong-base resins. The uranium usually is precipitated with ammonia to produce ammonium diuranate (yellow cake). 

Growth and decay of Ra after isolation of radium from 4n series at secular equilibrium. The top curve gives the decay of Ra after the first isolation relative to the secular rate. The growth curve shows the time dependence of Ra that comes from Ra (via Ac and Th). The middle decay curve shows Ra that decays (with the clock restarted) after thorium is removed when growth and decay are equal (about 22 days from t = 0). The bottom decay curve shows decay following a third purification (about 10 days after the second]... 

Continuing to work with the pitchblende they had used to extract polonium, the Curies found that it showed traces of yet another substance, which after much separation and purification, displayed an even more pronounced level of radioactivity, amounting to about 900 times that of uranium.This element, ako discovered in 1898, was named radium. 

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