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  Web Book Home Page | Chemogenesis Main Index Foreword:  Chemogenesis & Chemical Education Part I   Atoms | Elements | Periodic Tables 1.1  Introduction to Chemogenesis 1.2  Nucleosynthesis of The Elements 1.3  The Segrè Chart 1.4  Quantum Numbers to Periodic Tables 1.5  The Periodic Table: What Is It Showing? 1.6  The INTERNET Database of Periodic Tables 1.7  Periodicity Part II   Structure | Bonding | Material Type 2.1  Mono-Bond Typed Binary Compounds 2.2  Binary Compound Synthlet 2.3  Electronegativity 2.4  van Arkel-Ketelaar Triangles of Bonding 2.5  Tetrahedra of Structure, Bonding & Material Type 2.6  Structure, Bonding & Material Synthlet 2.7  The Classification of Matter: Chemical Stuff Part III   Interactions | Reactions | Mechanisms 3.1  The Chemogenesis Analysis: An Overview 3.2  Lewis and Brønsted Models of Acidity 3.3  The Hard Soft [Lewis] Acid Base Principle 3.4  Main Group Elemental Hydrides 3.5  Five Hydrogen Probe Experiments 3.6  Congeneric Dots, Series & Planars 3.7  Quantifying Congeneric Behaviour 3.8  Ligand Replacement Congeneric Series 3.9  Congeneric Array Interactions 3.10  Emergence of Organic Chemistry 3.11  Congeneric Array Database 3.12  The Five Reaction Chemistries 3.13  Lewis Acids & Lewis Bases: A New Analysis 3.14  The Lewis Acid/Base Interaction Matrix 3.15  Patterns in Reaction Chemistry Poster 3.16  Lewis Acid/Base Interaction Matrix Database 3.17  Nucleophiles, Bases & The Fluoride Ion 3.18  Redox Chemistry 3.19  Redox Chemistry Synthlet 3.20  Radical Chemistry 3.21  Diradical Chemistry 3.22  Photochemistry 3.23  Species/Species Interactions 3.24  The Simplest Mechanistic Step: STAD 3.25  Unit & Compound Mechanistic Steps 3.26  The Mechanism Matrix 3.27  Addition To A Double Bond Synthlet 3.28  Pericyclic Reaction Chemistry Part IV   Chemical Theory 4.1  Why Do Chemical Reactions Occur? 4.2a  Thermochemistry: List Reactions Synthlet 4.2b  Thermochemistry: Play With Reaction Synthlet 4.2c  Thermochemistry: Bulid A Reaction Synthlet 4.3  Timeline of Structural Theory 4.4  Modern Lewis Theory 4.5  Valence Shell Electron Pair Repulsion: VSEPR 4.6  Diatomic Species by Molecular Orbital Theory 4.7  Polyatomic Species: Molecular Orbitals 4.8  Organic π-Systems 4.9  Functional Group Database Part V   Complexity & Emergence 5.1  Chemistry & Complexity: Systems 5.2  Linear Chemistry Systems 5.3  Chemical Systems Prone to Complexity Part VI   Extras 6.1  Chemogenesis Videos 6.2  Chemical Thesaurus Reaction Chemistry Database 6.3  Paper: Chemogenesis 6.4  Paper: Electronegativity as a Basic Elemental Property (FoC) 6.5  Workshop: What is Chemistry? 6.6  Paper: Scientific laws, Dalton’s postulates, chemical reactions
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Actinium: The Most Annoying Element for the Rare-Earth Industry?

Koen Binnemans writing on Linkedin:

Actinium: The Most Annoying Element for the Rare Earth Industry?

Rare-earth elements (REEs) are often accompanied by radioactive uranium and thorium in their ores. This is particularly problematic for monazite, which can contain more than 15 wt% thorium dioxide. The REE mineral steenstrupine, which occurs in large quantities in Greenland, is so rich in uranium that it can even be mined as a uranium ore. Due to strict safety regulations governing the handling of naturally occurring radioactive materials (NORM), the thorium content of REE ores poses major challenges for REE producers. Thorium is treated as radioactive waste, and its disposal can be very expensive.

It is important to realize that most radioactivity issues are not caused directly by thorium or uranium themselves, since their primary isotopes (thorium-232, uranium-235, and uranium-238) are all very long?lived, but by their radioactive daughter nuclides formed through decay chains.

Most of these radioactive daughter elements have chemical properties sufficiently different from those of the REEs that they can be removed using conventional hydrometallurgical techniques.

However, actinium presents a particular challenge because its chemical properties are similar to those of the REEs, especially lanthanum. The isotope actinium-227, formed by the decay of uranium-235, has a half-life of 22 years. During REE separation, actinium tends to follow lanthanum. In a solvent-extraction circuit, actinium accumulates in the SX battery along with the lanthanum stream.

Although the concentration of actinium is usually very low, lanthanum must be purified as thoroughly as possible, because one important application of lanthanum is in scintillator detectors for ionizing radiation (e.g. (LaBr₃:Ce³⁺ or LaCl₃:Ce³⁺). If lanthanum is contaminated with radioactive actinium, the resulting detector will exhibit significant background noise and therefore poor performance. Another issue is that REE concentrates produced at mining sites may exceed legal radioactivity limits for export to REE refineries due to the presence of actinium.

Therefore, REE processing companies have developed processes to remove actinium from REE concentrates or feed solutions for SX operations. Limited information is available in the scientific literature, but more can be found in patent documents. For instance, read the following patent of CARESTER, https://lnkd.in/evXsXzDB

It should also be noted that actinium has useful applications: actinium?225 is used in radiopharmaceuticals for the precision treatment of tumors. See: PANTERA

SOLVOMET R&I Centre SIM2 KU Leuven

Oak Ridge National Laboratory (Wikipedia) Blue Cerenkov radiation emitted by a sample of actinium-225

© Mark R. Leach Ph.D. 1999 –

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