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Appel, P.*; Na-Oy, L.*; Hatsukawa, Yuichi; Osawa, Takahito; Kystol, J.*; S
rensen, L.*
Danmarks og Grnlands Geologiske Undersgelse Rapport, Vol.127, 39 Pages, 2011/12
This report presents the results of experiments involving the revival of an old method for removal of mercury from tailings after gold extraction by small-scale miners. Numerous tailings from small-scale gold mining are found throughout the Philippines. The tailings have proved to contain large amounts of mercury (up to 250 gram per ton). Furthermore, the tailings contain large amounts of gold locked-up in the mercury - up to 16 gram per ton. The mercury occurs as mercury flour (globules less than a millimetre across). Mercury flour is produced through milling of gold ore, when the mercury is added to tailling drums (whole ore amalgamation). The globules "hidden" in the mercury flour cannot be recovered by small-scale gold miners in any environmentally benign ways.
-ray analysis and instrument neutron activation analysisOsawa, Takahito; Hatsukawa, Yuichi; Appel, P. W. U.*; Matsue, Hideaki
Nuclear Instruments and Methods in Physics Research B, 269(8), p.717 - 720, 2011/04
Times Cited Count：16 Percentile：75.64(Instruments & Instrumentation)The authors have established a method of determining mercury and gold in severely polluted environ-mental samples using prompt -ray analysis (PGA) and instrumental neutron activation analysis (INAA). Since large amounts of mercury are constantly being released into the environment by small-scale gold mining in many developing countries, the mercury concentration in tailings and water has to be determined to mitigate environmental pollution. PGA can determine high mercury concentrations in polluted samples as it has an appropriate level of sensitivity. Moreover, gold concentrations can be determined sequentially by using INAA after PGA. In conclusion, the analytical procedure established in this work using PGA and INAA is the best way to evaluate the degree of pollution and the tailing resource value. This method will significantly contribute to mitigating problems in the global environment.
Jorgrnsen, U.*; Appel, P. W. U.*; Hatsukawa, Yuichi; Frei, R.*; Oshima, Masumi; Toh, Yosuke; Kimura, Atsushi
Icarus, 204(2), p.368 - 380, 2009/12
Times Cited Count：28 Percentile：58.48(Astronomy & Astrophysics)The solid planets assembled 4.57 Gyr ago during a period of less than 100 Myr, but the bulk of the impact craters we see on the inner planets formed much later, in a narrow time interval between 3.8 and 3.9 Gyr ago, during the so-called Late Heavy Bombardment (LHB). It is not certain what caused the LHB, and it has not been well known whether the impactors were comets or asteroids, but our present study lend support to the idea that it was comets. During a field expedition to Isua, Greenland, we sampled three types of sedimentary river load from larger areas of surrounding land surface and of contemporaneous seawater. Our samples show evidence of the LHB impacts that took place on Earth, by an average of a seven times enrichment (150 ppt) in iridium compared to present day ocean crust (20 ppt).
Hatsukawa, Yuichi; Osawa, Takahito; Appel, P. W. U.*; Arcilla, C.*; Perez, E.*
no journal, ,
Small scale gold mining is widely seen in many places in the world. During gold extract processing, large amount of mercury was released in the environment. Extrapolated to the whole country 200 to 500 tons of mercury is released to the environment every year. Most of the mercury will end in the mangrove swamps fringing the coast line. The mangrove swamps serve as hatching grounds for fish and shellfish the main source of proteins for the Filipinos. Very high concentrations of mercury have been found in water which was used for watering rice paddies. In this study, we developed determination of mercury and gold in the crushed rock mines nondestructively using PGAA and INAA. Also based on the concentration of gold and mercury in tailings, we will optimize conditions of the state battery method. Observed mercury and gold concentrations in tailings are 2.5-393 ppm, 1-3.9 ppm, respectively. Based on these results, we will optimize the conditions of the state battery method for mercury clean up project.
