Leaching characteristics and kinetics of radioactive element uranium and thorium from Ta/Nb tailing

Enhancement of Uranium Recycling from Tailings Caused by the Microwave Irradiation-Induced Composite Oxidation of the Fe–Mn Binary System

“…The utilization of uranium has been closely linked to human society since the industrial age, such as to fuel nuclear power plants in the civilian sector and to make high-density penetrators in the military counterpart. − U is normally extracted from the U-bearing ores by grinding and leaching (e.g., biotic and abiotic) techniques in combination after the mining activities. − U tailings are produced after U-related minerals and separated from raw ore sands via leaching. − The U tailings are commonly stored or stacked in huge impoundments, which retains up to 85% of the radioactivity of original U ores emitting to surroundings due to the residual existences of some contained radioactive nuclides such as uranium-238 ( 238 U), uranium-235 ( 235 U), thorium-230 ( 230 Th), and radium-226 ( 226 Ra). − In China, most of the U tailings are stored in the open air at present. Although the environmental hazards posed by the U tailings have attracted more attention, the old reservoir way is still maintained in some stockpiling regions due to the blurred responsibilities and the shortage of funds. − Therefore, the radionuclides and some coexisting heavy metals (HMs) contained in the tailings can be potentially migrated into groundwater from the surface by heavy rains and carried great distances by strong winds, finally entering the biological terminals through the food chain and threatening the ecosystem operations. − The residents can be exposed to uranium and its radioactive daughters by ingesting contaminated food and water and even by inhaling sand dust in the air. Furthermore, long-time uranium exposure will cause severe damage to the normal functioning of some organs (e.g., heart, liver, and kidney) and the nervous system. − …”

“…Commonly, the low content percent of carbonate minerals means that the acid lixiviants combined with some surfactants and oxidants are used to treat the U tailings in preference. ,, However, the refractory characteristics of U tailings caused by the gangue compositions and the residuals in all links will consume much higher acid concentrations or more complexing agents, trying to elevate the efficiency levels during the leaching process. ,,− Correspondingly, the costs will be surprisingly increased, and more engineering legacy issues such as secondary pollution and ecological remediation will be produced. Some appropriate pretreatments and enhancements should be explored to avoid the dependence on higher acid concentrations.…”

Activation mechanism of tantalum niobium flotation by lead ions in a combined collector flotation system

“…However, the nature of domestic ore is complex, which needs to be treated in combination with gravity, magnetism, electricity, flotation, and metallurgy purification processes. Although the flotation method does not play a leading role in the separation process of TNO, it has a significant recovery effect on tantalum, niobium, tungsten, and tin ores with similar physical properties (Li et al, 2019;Liu et al, 2020;Thi Hong and Lee, 2019).…”