Radioactive Waste Of Rare Earth Smelting Industry In Jiangsu Province Pollution Control Research

Rare earth mineral resources are very rich in China, and the rare earth reserves and exports of rare earth products both are No.1 in the world. But the rare earth mineral resources associated with above natural background levels of radioactive nuclides(such as thorium, uranium and radium), and in the process of mining, smelting, processing and utilization of associated radioactive material with the migration, concentration and diffusion, and waste products will have different levels of radioactivity, caused a certain amount of radioactive pollution on the surrounding environment, to the staff and caused additional public exposure dose. Therefore, we need to find a suitable disposal plan, to dispose of rare earth waste residues, eliminate environmental security hidden danger.This thesis is based on "low rare earth smelting industry environmental protection scientific research project in Jiangsu province, Jiangsu province put waste radioactive pollution control technology research" as the backing, materials of rare earth smelting industry in Jiangsu province, low residual radioactive solution control method is studied. Mainly from the equilibrium and non-equilibrium cases nuclide activity analysis of non-equilibrium cases gamma radiation dose rate and concentration of activity research, rare earth smelting process and disposal of radioactive research suggests three aspects of research, finally get the following conclusion:(1) In the rare earth tail ore radioactive equilibrium has been destroyed, and the actual measurement result comparison, the results show that the multiple characteristics under the condition of non-equilibrium nuclide common calculation of activity method, and the activity of rare earth actually closer to. Thorium series nuclides in the balance after the destruction of activity changes with time and matrix and the initial activity of 228 Ra concentration. Uranium series isotopes in the balance after the destruction mainly two daughters(234Th and 226 Ra and their daughters) of radioactive contribution to give priority to. For rare earth tail ore balance is destroyed, only measuring a single daughter of activity concentration does not guarantee that no other activity of nuclide concentration exceeding the standards, activity of nuclide concentration measurement characteristics, thus calculated decay chain in the activity of each nuclide concentration and total activity concentration, the standard of the relevant maneuverability strong immunity, offer reference for rare earth smelting factory apply for exemption from waste residue is of great significance.(2) To establish the relationship between the gamma dose rate and concentration of activity, combined with the unbalanced situations of radioactive series segmentation theory, get absorbed dose rate and feature relationship formula of nuclide concentration of activity. In addition, establish the gamma dose rate and activity levels, dual protection of the rare earth waste radioactive measurement accuracy. Refer to the IAEA to public annual effective dose limit and management mode and the limit of NORM, Canada was calculated based on annual effective dose to the public of 0.3mSv/a and 1mSv/a of limit exemption limit and management. Is obtained by the first and the second experiment, the measured results with the results of laboratory analysis in line with the good, to verify the theory is correct, also revised the problems existing in the operation, such as sample size, sample weight, slag forms such as the impact on the field practice.(3) In view of the rare earth smelting process, from acid dissolution process and the final effluent can deal with two links are optimized. Acid soluble barium radium coprecipitation process, can the experiment to determine the optimal proportion of adding reagent, also can use the new reagents, in addition to radioactive matter such as a new type of ion exchanger selective adsorption radioactive nuclide, both for radionuclide recycling, but also to reduce the level of radioactivity in the follow-up process; Neutralization process can also be used in new except auxiliary reagent, reduce the radioactivity in the neutralizing slag, below the exemption limit, reduce the storage of waste residue stress by enterprises. According to the gamma photons in the rare earth has been clear about the effective thickness of slag sample and the shape and size of slag samples, put forward the operable waiver process. Moreover research analyzes ten of the rare earth plant acid slag and slag for the main ingredients, advances some Suggestions on waste recycling, for recycling useful nuclide in acid slag and exemption from slag and to provide the reference.