Uranium Ore Processing Research Articles

Current Directions of Educational Activity of SSTC NRS

The paper describes the main areas of educational activities on nuclear and radiation safety, which have been formed in recent years and are currently implemented by the State Enterprise "State Scientific and Technical Center for Nuclear and Radiation Safety" (SSTC NRS). The experience of SSTC NRS in conducting training and advanced training for personnel of domestic enterprises on nuclear energy use is related to nuclear and radiation safety, radiation safety in using radiation sources (industry and medicine), mining and processing of uranium ores. The paper describes specialized areas of training prepared at the request of nuclear companies, in particular: support and training of management staff of NNEGC "Energoatom", transfer of experience in the use of computer codes and programs, exercise of practical approaches to the application of guidelines for severe accident management, training on indigenous analysis of NPP abnormal operation. The participation of SSTC NRS in international programs, projects and initiatives on training and transfer of experience within the EU technical assistance program Instrument for Nuclear Safety Cooperation and the Euratom Research and Training Program provides information on new initiatives for training on nuclear and radiation safety.

Sensor-based ore sorting in 2020

Abstract Sensor-based ore sorting is not a new technology. It has been around since more than 70 years, mainly for diamond concentration, where it was applied to eliminate the security risk of diamonds being stolen from the previously applied grease-tables [13]. Despite a few installations in uranium ore processing, it had no further widespread acceptance in the minerals industry, mainly due to low design capacity. Besides that, sensor-based colour sorters were used in the food industry for small particle sizes (e. g., rice cleaning). It is fact that the first machine designs appropriate for coarse bulk materials were not developed for the minerals industry, but for the upcoming recycling industry for plastics, glass, paper, metals in the late 1980s. In this sector, besides some magnetic separators, all the work was done by manual hand-picking, and it needed automation. After some years of optimization, these machines showed reliable performance under harsh conditions in scrap yards and recycling plants. Then, finally, the minerals industry, which at first was not convinced that this rather complicated machines were suited to be used with minerals, began with the first applications. These first installations of sensor-based ore sorters around the late 1990, all of them equipped with line-scan optical cameras, were mainly in industrial minerals, such as calcite, magnesite, quartz or rock salt. Since then, the technology has seen an enormous development in terms of available sensors, design capacity and availability, and the number of installations for minerals is growing – steadily but slower than expected, considering the many advantages it brings.

Magnetic assisted separation of uranium(VI) from aqueous phase using diethylenetriamine modified high capacity iron oxide adsorbent

Processing of uranium ore for the production of reactor-grade uranium results in the generation of large amount of aqueous waste containing small quantities of uranium, but higher than the guideline value (15 μg L−1) recommended by World Health Organization (WHO). The presence of uranium in aqueous waste poses several hazards and environmental issues due to the radioactive nature and migration behavior of uranium in the geosphere. In order to remove uranium (VI) from aqueous waste, the diethylenetriamine modified high capacity magnetic iron oxide adsorbent, abbreviated as Fe-DETA, was prepared and studied for the extraction of uranium from aqueous solutions. The Fe-DETA was characterized by X-ray diffraction, thermal analysis, infrared and Raman spectroscopy, and scanning electron microscopy. Significantly high amount (2 mmol g−1) of diethylenetriamine functional group (DETA) was anchored on magnetic iron oxide particles. The extraction of U(VI) from aqueous phase was studied as a function of pH of the aqueous phase, duration of the contact between Fe-DETA and aqueous phase, concentration of U(VI) in aqueous solution etc. The data on the rate of extraction of U(VI) in Fe-DETA was fitted into the first order and second order rate equations. The apparent uranium extraction capacity on Fe-DETA was determined to be 236 mg g−1, which correspond to the formation of 1:2 complex of U(VI) to diethylenetriamine ligand in Fe-DETA phase. The loaded U(VI) in Fe-DETA was quantitatively recovered using dilute Na2CO3 solution, and the recovered Fe-DETA was recycled for further extraction of U(VI), without any change in the apparent U(VI) extraction capacity.

THE USE OF DECONVOLUTION TECHNIQUE FOR THE ANALYSIS OF GAMMA SPECTROMETRY DATA FROM FIELD MONITORING USING UNMANNED AERIAL VEHICLES.

Airborne gamma spectrometry is an effective tool for prompt monitoring and mapping of large areas contaminated after NPP accident, radionuclides leakage cases, an impact of uranium ore mining and processing, etc. Airborne spectrometry data analysis using deconvolution technique enables to calculate air kerma rates and/or radionuclides concentrations as well as identification of radionuclides. Application of this technique on the airborne data (from manned as well as an unmanned survey using drones) is rather specific due to the requirements for short time of one scan data acquisition, a relatively long distance from the source and small detector size, due to the limited payload of the usually used drones. Application of deconvolution techniques for analysis of spectra with very poor statistics, methods and possibilities to improve the processing of such spectra are discussed.

Radiometric and environmental impacts of mill tailings at experimental plant processing unit, Allouga, Egypt

Uranium mining and ore processing are known to be harmful to the environment and human health if the waste generated is not managed properly. The aim of the present study is to determine the radiological indices in the mill tailings and review the possible attempts to utilize and minimize its hazardous effect. The activity concentrations of natural radionuclides, 238U, 232Th, 226Ra, and 40K have been measured by gamma spectrometry using HP-Ge detector. The average activity concentrations of 238U, 232Th, 226Ra, and 40K in the tailings wastes were 2071.8, 59.92, 6921.262, and 445. 57 Bq/kg respectively which are higher than the international average limit. The ranges of hazard indices such as Radium equivalent activity (Raeq), external hazard index (Hex), internal hazard index (Hin), γ-radiation hazard index Iγ, Dose rate (nGy/h) and annual effective dose equivalent (AED), were estimated. Uraniumm isotopic ratios in the ore –material and mill tailing samples indicate migration out of radionuclides to the surrounding environment causing contamination and many dangerous diseases. Fairly, all investigated tailing waste samples do not satisfy the universal standards, the studied wastes relatively still have high uranium contents and need reprocessing.

Wolfgang Beyer: A Groundwater Scientist from Dresden.

Wolfgang Beyer: A Groundwater Scientist from Dresden.

Concentration of rare-earth elements by sorption from sulphate solutions

Constantly increasing demand for rare-earth elements contributes to the involvement in the production of ore processing waste, the content of not extracted REE in which is quite large. One of the types of such waste is man-made mineral formations from the processing of phosphate uranium ores, which serve as raw materials for the production of REE concentrate at SARECO LLP. The technology for producing a concentrate includes the following redistribution: opening of raw materials cleaning of productive solutions from impurities; obtaining a concentrate on rare earth elements. One of the main disadvantages of this technology is the coprecipitation of almost 30% REE with ferrous cake when cleaning the most productive solution from impurities. To extract the rare earth elements ferrous cake is leached with sulphuric acid. The article studies the process of sorption from both model solutions that are similar in composition to the productive leaching of ferrous cake and directly from the productive ones, with the aim of further combining the resulting eluates with solutions supplied to precipitate REE.. Considerable attention has been paid to disrupt by ammonium salts.

Results of monitoring analisis of immunological parameters in employees of production sites located at the former mining and uranium ore processing territories

Aim. To study cellular and humoral immunological parameters of the employees of production sites located at the former mining and uranium ore processing territories. Materials and methods. In this work the clinical laboratory and immunological methods of examination were used. Statistical processing of the results was performed by using nonparametric analysis methods in the StatSoft Statistica 6 software package. Results. 101 employees of Chepetskiy mechanical plant were examined at the age of 19-62. 76 (75.2%) of them contacted with industrial factor, 64 - with radiation and 12 - with chemical. 25 (24.8%) employees had no contact with industrial factor. The immunological examination of the employees in contact with industrial factor revealed laboratory signs of imbalance in the immune system with IgE-overproduction. The risk group for secondary immunodeficiency with the leading infectious syndrome was 15.8%. Conclusion. Changes of cellular and humoral parameters on average values were not revealed. Infectious syndrome - recurrent ETN viral infections (13.9%) and herpes virus infection (13.9%) prevailed in the structure of the employees of Chepetskiy mechanical plant. A statistically significant difference in the content (percentage and absolute) of CD16+ lymphocytes was found in the employees of Chepetskiy mechanical plant contacted with industrial factor. These results had no clinical significance, what can be considered as an adaptive response to the chemical factor.

Applicability of thickened waste of hydrometallurgical uranium ore processing as backfill in underground mines

Applicability of thickened waste of hydrometallurgical uranium ore processing as backfill in underground mines

Efficient Technology for Combined Processing of Silicate and Carbonate Uranium Ores

The results of studies on the processing of carbonate ores with extraction of uranium and molybdenum by means of autoclave and atmospheric leaching and sorption extraction of valuable components using carboxyl cationionites and strongly basic anionites are presented. The most stable and highest indices for the extraction of uranium and molybdenum into solution were obtained for autoclave leaching with the following process parameters: pressure 12–14 psig, temperature ~140°C, pulp processing time 4–6 h, and initial sodium carbonate concentration 40–50 g/dm3. The degree of extraction of uranium and molybdenum into solution was ≥96%. Almost complete separation of uranium from molybdenum was obtained on carboxyl cationites without bicarbonate solutions in the pH range 6.5–7.5. An efficient technology is proposed for combined processing of silicate and carbonate ores using a unified sorption scheme making it possible to extract uranium and molybdenum separately while obtaining ammonium uranyl tricarbonate and ammonium paramolybdate.

Rare-Earth Concentrate Production From Technogenic Mineral Formations

<p>Based on the analysis technology of processing of uranium-containing raw materials, identified potential sources of rare earth elements from among the industrial products and waste: uranium sorption tails, sulfuric acid solutions of heap leaching of uranium, man-made mineral formations from phosphate processing of uranium ores. Based on the analysis technology of processing of uranium-containing raw materials, identified potential sources of rare earth elements from among the industrial products and waste: uranium sorption tails, sulfuric acid solutions of heap leaching of uranium, man-made mineral formations from phosphate processing of uranium ores.</p>

Understanding controls on redox processes in floodplain sediments of the Upper Colorado River Basin

Floodplains, heavily used for water supplies, housing, agriculture, mining, and industry, are important repositories of organic carbon, nutrients, and metal contaminants. The accumulation and release of these species is often mediated by redox processes. Understanding the physicochemical, hydrological, and biogeochemical controls on the distribution and variability of sediment redox conditions is therefore critical to developing conceptual and numerical models of contaminant transport within floodplains. The Upper Colorado River Basin (UCRB) is impacted by former uranium and vanadium ore processing, resulting in contamination by V, Cr, Mn, As, Se, Mo and U. Previous authors have suggested that sediment redox activity occurring within organic carbon-enriched bodies located below the groundwater level may be regionally important to the maintenance and release of contaminant inventories, particularly uranium. To help assess this hypothesis, vertical distributions of Fe and S redox states and sulfide mineralogy were assessed in sediment cores from three floodplain sites spanning a 250km transect of the central UCRB.The results of this study support the hypothesis that organic-enriched reduced sediments are important zones of biogeochemical activity within UCRB floodplains. We found that the presence of organic carbon, together with pore saturation, are the key requirements for maintaining reducing conditions, which were dominated by sulfate-reduction products. Sediment texture was found to be of secondary importance and to moderate the response of the system to external forcing, such as oxidant diffusion. Consequently, fine-grain sediments are relatively resistant to oxidation in comparison to coarser-grained sediments. Exposure to oxidants consumes precipitated sulfides, with a disproportionate loss of mackinawite (FeS) as compared to the more stable pyrite. The accompanying loss of redox buffering capacity creates the potential for release of sequestered radionuclides and metals. Because of their redox reactivity and stores of metals, C, and N, organic-enriched sediments are likely to be important to nutrient and contaminant mobility within UCRB floodplain aquifers.

Macroinvertebrate herbivores and epilithon algae community of a stream affected by mineralized heated mining water inflow

The main aims of this study were to analyse the effect of a mineralized heated water inflow from a uranium ore processing plant on the abundance and diversity of epilithon and macroinvertebrate herbivores as well as to identify changes in functional feeding groups. In total, four sampling sites were selected. One site was on the mining water tributary and three sites in a recipient natural stream (the Nedveˇdicˇka River, Czech Republic): one of them upstream and two downstream from the mining effluent. Samples were taken monthly during the period 2008–2009. The number of species in the epilithon was higher downstream from the tributary and we also recorded a small increase in density. We observed significant changes in the taxonomical composition of epilithon and macroinvertebrate communities downstream from the tributary. Taxa richness of macroinvertebrates was similar between sampling sites. A small drop in macroinvertebrate abundance immediately downstream from the tributary was followed by a significantly elevated number of herbivores, especially scraper-collectors, at the more downstream site. Alteration of the species composition and abundance of herbivorous macroinvertebrates in the Nedveˇdicˇka River could be explained by a combination of a change in food availability and the physico-chemical properties of the water.

Supercritical Extraction by Carbon Dioxide of Uranium from Ore Concentrates and Low-Enriched Ores of Tailing

The extraction and processing of uranium ores in Ukraine have led to the accumulation of large amounts of waste. It is obvious that the old technologies are not applicable to the extraction of uranium from such waste. Therefore, the search for the new, more efficient methods of extracting residual amounts of waste nutrients and subsequent improvement of the environmental status of contaminated areas are both necessary. The supercritical carbon dioxide fluid extraction (SFE-CO2) is proposed as a method that can be utilized independently or as the last step of the acid leaching method adopted at VostGOK to extract the uranium. The efficiency of uranium SFE-CO2 can reach 98%.

Tracking legacy radionuclides in St. Louis, Missouri, via unsupported 210Pb

Analysis of 287 soil, sediment and house dust samples collected in a 200 km2-zone in northern St. Louis County, Missouri, establish that offsite migration of radiological contaminants from Manhattan Project-era uranium processing wastes has occurred in this populated area. Specifically, 48% of samples (111 of a subset of 229 soils and sediments tested) had 210Pb concentrations above the risk-based soil cleanup limits for residential farming established by the US Department of Energy at the Fernald, OH, uranium plant, which handled and stored the same concentrated Manhattan Project-era wastes; the geographical distribution of the exceedances are consistent with water and radon gas releases from a landfill and related sites used to store and dispose of legacy uranium wastes; and offsite soil and house dust samples proximal to the landfill showed distinctive secular disequilibrium among uranium and its progeny indicative of uranium ore processing wastes. The secular disequilibrium of uranium progeny in the environment provides an important method for distinguishing natural uranium from industrial uranium wastes. In this study, the detection of unsupported 210Pb beyond expected atmospheric deposition rates is examined as a possible indicator of excessive radon emissions from buried uranium and radium-containing wastes.

Alkaline Processing of Uranium Ores of Indian Origin

This paper describes the R & D studies made in the development of oxidative alkaline processing schemes for the recovery of uranium from two carbonate hosted uranium ores of India namely, the Tummalapalle in Andhra Pradesh and Gogi in Karnataka. The U3O8 content of the Tummalapalle ore is about 0.04 % and that of Gogi is 0.2 %. The complexity associated with uranium mineralisation in both these ores is completely divergent. The nature of uranium mineralisation in the medium-grade Gogi ore is of simple oxide type, however the challenge lies in developing a single hydrometallurgical process scheme capable of recovering uranium present in both limestone and granite host rocks, which co-exists in the mineralised zone. Processing of Tummalapalle uranium ore is also equally formidable for a variety of reasons, chiefly, lean tenor, very-fine to ultra-fine size dissemination of uranium in gangue matrix and significant presence of reactive sulfide minerals. These challenges were addressed by minimizing the number of unit operations, incorporating regeneration and reagents-recycle loops and, adopting efficient water conservation measures. The alkaline processing of uranium ores is adopted for the first time in India and it is one amongst the few countries in the world to use this technology for the recovery of uranium from lean-tenor ores.

Assessment of Human Exposure to Dissolved Radon in Groundwater around the Uranium Industry of Jaduguda, Jharkhand, India

Measurement of dissolved radon and 226 Ra in groundwater was carried out in 30 different locations around the uranium mining and ore processing area of Jaduguda, Jharkhand, India. Activity concentration of 226 Ra was found to be very low, whereas dissolved radon was observed to be slightly elevated due to geological features of the area consisting of uranium mineralization. No definite relation was observed between radon and 226 Ra in groundwater. The annual dose due to ingestion of radon containing water estimated at 60% locations was less than 100 μSv. The maximum ingestion dose was found to be 300 μSv to adult members of the public. The average dose due to the ingestion of radon in water was 94 μSv, which is less than the stipulated limit of 1000 μSv prescribed by regulatory body.

Radiological impact of surface water and sediment near uranium mining sites

The aim of this study is to assess the radiological impact of surface water and sediment around uranium mining sites 20 years after their closing. The areas under observations are 31 former classical underground uranium mining and exploratory sites in Bulgaria, named as objects. The extraction and processing of uranium ores in the Republic of Bulgaria were ended in 1992. To assess the radiological impact of radionuclides field expeditions were performed to sample water and bottom sediment. The migration of uranium through surface water was examined as one of the major pathways for contamination spread. The range of uranium concentration in water flowing from the mining sites was from 0.012 to 6.8 mgU l−1 with a geometric mean of 0.192 mgU l−1. The uranium concentrations in water downstream the mining sites were approximately 3 times higher than the background value (upstream). The concentrations of Unat, 226Ra, 210Pb, and 232Th in the sediment of downstream river were higher than those upstream by 3.4, 2.6, 2, and 1.7 times, respectively. The distribution coefficient of uranium reflects its high mobility in most of the sites. In order to evaluate the impact on people as well as site prioritization for more detailed assessment and water management, screening dose assessments were done.

Study on treatment of radioactive liquid waste from uranium ore processing by the use of nano oxide ferromagnetic

Nano oxide ferromagnetic Fe3O4 KT wich was produced by the Military Institute of Science and Technology ​​were used to adsorbed heavy metal elements in liquid waste. In this report, the nano oxide ferromagnetic Fe3O4 KT with the particle size of 80-100nm and the specific surface area ​​of 50-70m2/g was applied to study the adsorption of radioactive elements in the liquid waste of uranium ores processing. The effective parameters on adsorption process included temperature, stirring rate, stirring time, the pH value of the solution, the initial concentration of uranium in solution were investigated. The results showed that the maximum adsorption capacity for uranium of the nano Fe3O4 KT was 53.5 mgU/g with conditions such as: room temperature, stirring speed 120 rounds/minute, the pH value of solution was 8, stirring time about 2 hours . From the results obtained, nano Fe3O4 KT was tested to treatment real liquid waste of uranium ore processing after removing almost heavy metals and a part of radioactive elements by preliminary precipitation at pH 8. The results were analyzed on the ICP-MS and α, β total activity equipment, the solution concentration after treatment suitable for Vietnamese Technical Regulation on industrial wastewater QCVN 40: 2011 (concentrations of heavy metals; total activity of α and β).

Leaching of brannerite in the ferric sulphate system — Part 1: Kinetics and reaction mechanisms

The uranium titanate mineral brannerite, UTi2O6 is the most common of the uranium minerals which is considered refractory. Ore containing brannerite mineralisation has been mined and processed in several locations around the world. Under typical uranium ore processing conditions, brannerite is often lost to tailings. In order to design an effective process for the leaching of high-brannerite uranium ores, it is first necessary to understand the mechanism of the chemical processes through which brannerite dissolves in the absence of interferences from the host rock. In the present study, a specimen of brannerite obtained as a single crystal was leached in sulphuric acid (10–200g/L) and ferric sulphate (2.8g/L Fe3+) solution at 25–96°C for 5h. The rate of titanium dissolution was monitored along with uranium. Comparisons between the rates at which these two elements dissolved and the morphological changes that were observed to take place during the dissolution process indicated two different sets of leaching reaction mechanisms. At low temperatures, uranium dissolved at a much higher rate than titanium initially, leaving titanium rich areas on the brannerite particles similar to observations reported in earlier investigations which suggest incongruent dissolution. The calculated activation energies for uranium and titanium dissolution were 36 and 48kJ/mol respectively. At higher temperatures, uranium and titanium dissolved at similar rates in constant proportions suggesting congruent dissolution. The calculated activation energy for this reaction was 23kJ/mol. The transition between incongruent and congruent dissolution took place at lower temperatures when the acid concentration was higher. Titanium appeared to undergo hydrolysis after dissolution, forming anatase. This side reaction was most favourable at lower acid concentrations and high temperatures.