Mobility of Ra-226 and Heavy Metals (U, Th and Pb) From Pyritic Uranium Mine Tailings Under Sub-Aqueous Disposal Conditions

2011 ◽  
Author(s):  
Nand K. Dave´
Keyword(s):  
Heavy Metals ◽  
Surface Water ◽  
Mine Tailings ◽  
Ion Concentration ◽  
Uranium Mine ◽  
Acid Generation ◽  
Shallow Zone ◽  
Acidic Conditions ◽  
Waste Repositories

Laboratory lysimeter studies were undertaken to evaluate the leaching characteristics and mobility of Ra-226 and other heavy metals (U, Th and Pb) from pyritic uranium mine tailings under sub-aqueous disposal conditions for assessing the long-term radiological stability of such waste repositories. The experiments were conducted using three types of un-oxidized tailings: fine, coarse and gypsum depleted mill total tailings. The results showed that Ra-226 was leached from surface of the submerged tailings and released to both surface water and shallow zone pore water during initial low sulphate ion concentration of the surface water cover in all three cases. The release of Ra-226 was further enhanced with the onset of weak acidic conditions in the surface water covers of both coarse and gypsum depleted mill total tailings. With additional acid generation and increasing sulphate and iron concentrations, the dissolved Ra-226 concentrations in the water covers of these tailings gradually decreased back to low levels. Pb was also leached and mobilized with the development of moderate acidic conditions at the surface of the submerged coarse and gypsum deplete tailings. No leaching of U and Th was observed.

scholarly journals Remediation of Boating and Jetty Pollutants from the Okavango Delta Surface Water Employing Valorized Tilapia ruweti Waste Material

2020 ◽  
pp. 1-12
Author(s):  
Irene W. Maina ◽  
Morlu G. F. Stevens ◽  
Bareki S. Batlokwa
Keyword(s):  
Heavy Metals ◽  
Surface Water ◽  
Water Samples ◽  
Contact Time ◽  
Ion Concentration ◽  
Okavango Delta ◽  
Waste Materials ◽  
Adsorption Parameters ◽  
Solution Ph ◽  
Surface Water Samples

Aims: To employ valorized waste materials from Tilapia ruweti scales for removal of heavy metals from areas with major boating activities and high numbers of jetties at the Okavango delta, Botswana. Study Design: Biowaste materials were Identified, valorized and then optimized for adsorption and removal of boating and jetty pollutants from profiled Okavango Delta surface water samples. Place and Duration of Study: Okavango Delta, Maun and Botswana International University of Science and Technology, Palapye, Botswana between March 2017 and September 2018. Methodology: Tilapia ruweti scales were collected from Sehithwa, Maun while water samples were collected from areas with jetties and major boating activities at Shakawe, Mboma Island and Xakanaxa. The concentration of Zn, Cu, Ni, Co, Pb and Cd at all the sampling sites were accurately determined using micro-plasma atomic emission spectroscopy (MPAES). The fish scales were pulverized and valorized by subjecting them to 12.7% vinegar. Minitab 14 software was used as a modeling tool to provide multivariate optimized parameters that affect sorption studies that included initial ion concentration, sorbent dose, contact time and solution pH. The valorized waste materials were then utilized for removal of the selected heavy metals. Results: The optimized adsorption parameters that included contact time, solution pH, sorbent dose and initial ion concentration were ≤ 88.63 min, ≤ 8.75, ≤ 84.29 mg and ≤ 28.44 mg/L respectively. The valorized Tilapia ruweti waste displayed high removal efficiencies toward removing the selected ions from the Okavango Delta surface water samples up to 94.21% with %RSD < 2 for n = 3 (triplicate). Conclusion: The valorized Tilapia ruweti scales were recommended as a cheap, simple and an effective method for remediation of boating pollution at the Okavango delta and other recreational areas.

Mobility of radium and heavy metals from uranium mine tailings in acid sulfate soils

Soil Research ◽  
1994 ◽  
Vol 32 (2) ◽  
pp. 335 ◽  
Author(s):  
IR Willett ◽  
BN Noller ◽  
TA Beech
Keyword(s):  
Heavy Metals ◽  
Uranium Mine ◽  
Acid Sulfate ◽  
Erosion Rates ◽  
Zinc Fractions ◽  
Mill Tailings ◽  
Two Samples ◽  
Sulfate Soils ◽  
Iron Manganese

This study was aimed at determining whether heavy metals in tailings from Ranger Uranium Mine (N.T.) change in chemical form in such a way that they will become more mobile, or bioavailable, after they are mixed with extremely acidic soils from downstream of the mine. Four soils were studied: two samples were acid sulfate (jarositic or pyritic) materials and two were acidic materials overlying acid sulfate horizons. Copper, iron, manganese, lead, uranium and zinc fractions were determined in soils to which uranium mill tailings had been added. Total and exchangeable 226Ra were also determined in selected samples. The tailings-soil mixtures were incubated for up to 4 months and included a comparison of reactions under continuously moist conditions and when subjected to a saturation and drying cycle. The tailings had considerably greater concentrations of total Mn, Pb, U and 226Ra than the soils. The heavy metals in the tailings occurred as relatively immobile forms. In the non-pyritic soils, the distribution of the metals between the fractions did not change much during 4 months of reaction. In the pyritic soil, which underwent oxidation and acidification during incubation, there were 2- to 3-fold increases in the exchangeable fractions of Fe, Mn, Cu and U. The metals in the tailings and soil behaved similarly. There appeared to be more likelihood of increased mobility of metals from oxidation of pyritic materials than from addition of tailings. The fraction of total 226Ra that was exchangeable decreased from 11% in the original tailings to 2-7% after reaction with three of the soils but increased to 44% in one soil. At estimated long-term erosion rates, the tailings are not likely to be a source of heavy metal pollution, but addition of 226Rato soils presents a possible radiological hazard.

In Situ Bioremediation of Tailings by Sulfate Reducing Bacteria and Iron Reducing Bacteria: Lab- and Field-Scale Remediation of Sulfidic Mine Tailings

2017 ◽  
Vol 262 ◽  
pp. 651-655 ◽  
Author(s):  
Xing Yu Liu ◽  
Ming Jiang Zhang ◽  
Yi Bin Li ◽  
Zi Ning Wang ◽  
Jian Kang Wen
Keyword(s):  
Heavy Metals ◽  
Mine Tailings ◽  
Sulfate Reducing Bacteria ◽  
Laboratory Scale ◽  
Ion Concentration ◽  
Field Scale ◽  
Iron Reducing Bacteria ◽  
Sulfate Reducing ◽  
Lead Zinc ◽  
Reducing Bacteria

To research the remediation efficiency of sulfate reducing bacteria and iron reducing bacteria on heavy metals, the remediation experiments of laboratory-scale and field-scale were conducted respectively with chalcopyrite tailings and 3 hectares lead-zinc sulfides mine tailings. The ion concentration of exudate was determined using inductively coupled plasma atomic emission spectroscopy, and key bacterial strains were investigated by real-time PCR. The laboratory-scale experiment of chalcopyrite tailings indicated pH of exudate rose to neutral, penetration time of exudate significantly increased, redox potential and dissolved iron notably decreased, and black metal sulfides were formed during remediation by sulfate reducing bacteria and iron reducing bacteria. The field-scale lead-zinc sulfides mine tailings remediation results indicated that the concentration of dissolved heavy metals in exudate decreased, and the growth of both moss and plants were promoted.

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