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[en] Diethylene Triamine (DETA) can be used to extract selectively base metals from hydroxide sludges which are produced in the treatment of acid mine drainage. Solubilized metal concentrations exceeding 40 g/L are obtainable which is in the range where electrowinning is a possibility for metal recovery. Electrowinning experiments were conducted on copper-DETA complexes. The solutions tested contained 8 g/L Cu, 32.5 g/L DETA (ca. 1:2 molar basis), and 5.8 g/L NaCl at pH 12.2 (sodium hydroxide). After several trials stainless steel electrodes were selected. Batch tests showed DETA was not degraded and Cu was electrowon at a current density ca. 200 A/m2, a voltage ca. 2.5 V, and a current efficiency of 100%. The deposits were easily removed but they were brittle. In recycle tests DETA concentration decreased to reach a steady state concentration of ca. 21 g/L. Copper deposit quality also decreased. The proposed process to recover base metals from waste sludge using DETA as a recyclable extractant and electrowinning of the solution appears technically feasible. (author)
Journal
Canadian Metallurgical Quarterly; ISSN 0008-4433; 
; v. 39(3); p. 291-296
; v. 39(3); p. 291-296
[en] The studied site is an old slate quarry in use from the first half of 20th century to 1965 located in Parc Natural de Collserola, in Barcelona. After some restore projects, from 1992 the quarry site has been used as an observatory of natural values of the zone. In this site, in between the slate there are associated minerals like marcasite and pyrite (FeS2 ) which, may be oxidized by water and atmospheric oxygen producing Fe3+ and sulphuric acid. This phenomena is commonly known as acid mine drainage (AMD). As a consequence of the acid leachates, several radionuclides may be extracted from the rocks and be distributed into effluents. In this study, a radiological characterization of soil, sediments and effluents of the aforementioned site are characterized. Total uranium activity in water samples is strongly related with the pluviometry since dilution effect is observed in rainy periods. However, the isotopic ratio 234U/238U in water samples remains constant around 1.2. Regarding soil samples, the concentration of uranium is constant in time but have an important spatial distribution. When you move away from the focus of AMD, the concentration of uranium in soil increase and isotopic ratio 234U/238U decrease.
[es]
El emplazamiento estudiado es una antigua cantera de pizarras que se explotó en la primera parte el siglo XX hasta 1965 localizada en el Parc Natural de Collserola, en Barcelona. Desde 1992 el emplazamiento se ha tratado de recuperar convirtiéndolo en un espacio de observación de los valores naturales del parque. Asociadas a las pizarras se encuentran minerales como la pirita y marcasita (FeS2 ) que se oxidan por efecto del oxígeno y el agua dado lugar a iones Fe3+ y ácido sulfúrico causando el proceso conocido como drenaje ácido de mina. Como consecuencia el carácter ácido de los lixiviados, se extraen de la roca distintos radionucleidos que se distribuyen mediante dichos efluentes. En este trabajo se realiza una caracterización radiológica de suelos, sedimentos y efluentes del emplazamiento mencionado. Se ha observado que concentración de uranio en las distintas balsas está estrechamente relacionada con la pluviometría de la zona observándose un efecto de dilución en los periodos más húmedos, sin embargo la relación isotópica 234U/238U permanece constante alrededor de 1.2. Por otra parte, las determinaciones a distintas distancias del foco confirman una distribución espacial variante tanto en lo referente a la concentración de uranio como a la relación isotópica 234U/238UJournal
[en] Uranium in acidic mine drainage from the former Ogoya Mine in Ishikawa Prefecture, Japan, and in neutral surface waters from its surrounding rivers was investigated from the viewpoint of radioactive disequilibrium in the uranium decay series. Water samples were periodically collected from the mine pithead and its surrounding rivers and their U isotopes (238U and 234U) were measured together with chemical components. The 238U concentrations in the water samples varied widely from 0.0036 to 0.78 mBq/L with a factor of about 200. High 238U concentrations were observed in the strongly acidic drainage (pH: around 3.5) from the pithead and the 234U/238U activity ratios showed significant values of as high as 10-15. By taking into account of the measurement of Th isotopes, it appeared that probable processes controlling the high 234U/238U activity ratios in acidic mine drainage were due to that the acidic water flowing from the mine pithead was formed only in the upper water layer of the pits and 234U was preferentially leached in the deeper underground water under the neutral and reducing conditions. (author)
Journal
Journal of Radioanalytical and Nuclear Chemistry; ISSN 0236-5731; ; CODEN JRNCDM; v. 283(3); p. 699-705
; CODEN JRNCDM; v. 283(3); p. 699-705
[en] A trace test and computational flow analysis were carried out in order to identify the flow characteristics of mine drainage in an existing oxidation pond. Consequently, despite the need for sufficient retention time of mine drainage to purify the mine drainage, the effective volume of an oxidation pond without any structure is too small and the time for mine drainage required to reach the outlet is also too short. To deal with this problem, computational flow analysis was carried out after systematically arranging the baffles in an oxidation pond. The initial arrival time to the outlet with baffles was more than 360 times compared to the case without baffles. Furthermore, exchange efficiency was also significantly increased from 14.5 to 82.7 %. Thus, adding baffles to an oxidation pond resulted in an increase in the volume of the oxidation pond in the flow range of mine drainage, enhancing the flow efficiency and retention time as well.
Journal
Environmental Earth Sciences; ISSN 1866-6280; ; v. 75(10); p. 1-9
; v. 75(10); p. 1-9
[en] Acid Mine Drainage (AMD) is a process that occurs in mining that has sulfide ores. With water and oxygen, several metals are oxidized, an example is uranium. At the mine site of the Osamu Utsumi Mine located at INB - Caldas and in two other mining tailings pile, AMD occurs in an accelerated way and currently, without technological solution. To reduce the amount of water inside the pit, there is a water pumping system for the effluent treatment plant where hydrated lime is added, generating waste water and an alkaline mud called DUCA. The DUCA has a concentration of approximately 0.32% of U3O8, which makes it interesting from the point of view of the metallurgical extraction of that metal. One of the processes that can be used is leaching. The objective of this work was to test the alkaline leaching to extract the uranium present in the DUCA. In order to perform this separation, it was necessary to determine the operating conditions for the process: leaching agent solution (1 mol/L Na2CO3, 1 mol/L NaHCO3, 1 mol/L NaHCO3 with 1 mol/L Na2CO3 and 0.75 mol/L NaHCO3 with 0.25 mol/L Na2CO3), temperature (25 °C, 50 °C, 70 °C and 90 °C) and leaching time (1 hour-6 hours). The parameters were tested with 200 mL pulp and 10% solids. U3O8 solubilization was obtained 80% when using leaching solution with 0.75 mol/L NaHCO3 with 0.25 mol/L Na2CO3, 4 hours reaction and 70 °C temperature. With these optimized parameters, it will be possible to improve the leaching for the largest amount of uranium can be extracted in the sample, to help solve the environmental impact caused by the wastewater from the treatment of acid waters and, in addition, to give an economical destination for this metal that is solubilized in the pit of the mine. (author)
Source
Fernandez, Oscar Jesus Choque; Jaime Henrique Barbosa da (eds.); Instituto Federal do Pará (IFPA), Belém, PA (Brazil); Universidade Federal do Sul e Sudeste do Pará (UNIFESSPA), Marabá, PA (Brazil); Universidade Federal do Pará (UFPA), Belém (Brazil); Secretaria de Mineração e Energia do Estado do Pará (SEDEME), Belém (Brazil); 2102 p; ISBN 978-85-62855-69-6; ; 2017; p. 1570-1577; 27. ENTMME: Brazilian national meeting on mineral treatment and extractive metallurgy; Belem, PA (Brazil); 23-27 Oct 2017; Available from the Library of the Brazilian Nuclear Energy Commission, Rio de Janeiro
; 2017; p. 1570-1577; 27. ENTMME: Brazilian national meeting on mineral treatment and extractive metallurgy; Belem, PA (Brazil); 23-27 Oct 2017; Available from the Library of the Brazilian Nuclear Energy Commission, Rio de Janeiro
[en] Water is one of the receptors most affected by the impacts caused, especially in the case of mining sulphides and, to a lesser extent, of coal. Acid Mine Drainage (AMD) is the main problem associated with these mining operations, producing extremely high impacts, and in many cases irreversible impacts, until now. A new concept of mining can make this activity compatible with the environmental preservation and also to the recovery of the environment affected by the old mining operations that today are in the process of reopening. This new concept implicates the paradigm of Circular Mining as a derivative of the concept of Circular Economy, considered as a strategy that aims to reduce both the entry of materials and the production of virgin waste, closing the “loops” or economic and ecological flows of resources. The present work discusses the paradigm of Circular Mining, focused on the Iberian Pyrite Belt, one of the most paradigmatic metallogenetic regions in the world. Based on some examples, expeditious calculations show the possibility of recovering base metals as well as strategic elements from acid mine drainage, thus obtaining important economic assets.
Journal
Environmental Earth Sciences; ISSN 1866-6280; ; v. 77(10); p. 1-6
; v. 77(10); p. 1-6
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