1,721,092 research outputs found
Decontamination of spring water polluted with heavy metals at the Casargiu mine site (SW Sardinia)
No full textAsymptomatic bilateral adrenal pheochromocytoma in a patient with a germline V804M mutation in the RET proto-oncogene
No full textNot available, see PD
Lisciviazione dell’arsenico da un concentrato di flottazione enargitico contenente oro
No full textThe deep mineralized bodies of the Italian Serrenti-Furtei gold-bearing deposit, located in southern Sardinia, contain substantial amounts of enargite-luzonite and pyrite with subordinate tennantite, covellite, chalcopyrite and arsenopirite. The gold, which occurs as grains of between a few tens of micrometres and submicron size, is not amenable to direct cyanidation. These ores are beneficiated by bulk flotation using sulphydryl collectors and the resulting concentrates are then pyrometallurgically processed to produce gold and copper. However, the concentrates contain significant amounts of arsenic, severely reducing their market value; the abatement of this highly toxic metal in the flue gas to comply with stringent emission limits, increases processing costs significantly.
In order to reduce the arsenic content in the concentrate that besides to be a serious environmental problem severely reduces their market value, we carried out an investigation on arsenic leaching from enargite-luzonite using two different leachant. In particular we tested NaClO and Na2S with NaOH. By suitably adjusting the main influencing variables both reagents was found to be effective. By using NaClO we achieved 96 % of arsenic removal without significant Au and Cu losses. By Na2S we leached almost 98 % of arsenic and also a not negligible quantity of gold, especially at Na2S high dosages, whereas not was Cu losses
Environmental problems related to the reuse or disposal of ashes deriving from combustion of coal and MSW
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Beneficiation of a gold bearing enargite ore by flotation and As leaching with Na-hypochlorite
No full textThe deep mineralized bodies of the Italian Serrenti-Furtei gold-bearing deposit, located in southern Sardinia, contain substantial amounts of enargite-luzonite and pyrite with subordinate tennantite, covellite, chalcopyrite and arsenopirite. The gold, which occurs as grains of between a few tens of micrometres and submicron size, is not amenable to direct cyanidation. These ores are beneficiated by bulk flotation using sulphydryl collectors and the resulting concentrates are then pyrometallurgically processed to produce gold and copper. However, the concentrates contain significant amounts of arsenic, severely reducing their market value; the abatement of this highly toxic metal in the flue gas to comply with stringent emission limits, increases processing costs significantly.
In order to reduce the arsenic content in the concentrates and hence the penalties incurred, we carried out an investigation on enargite leaching using sodium hypochlorite to selectively dissolve the arsenic.
By suitably adjusting the main influencing variables, leaching was found to be effective, achieving 96% arsenic removal without significant Au and Cu losses, increasing the commercial value per tonne of concentrate
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Heavy metal immobilization using fly ash in soils contaminated by mine activity
No full textOften the remedial measures required to clean up sites contaminated with heavy metals are so complex that their implementation becomes economically unsustainable. In these cases immobilization of the metal contaminants, by means of suitable soil amendments, is a promising and economically feasible technique for soil remediation. In this context, an experimental investigation has been carried out to assess the potential use of fly ash from coal-fired power stations for immobilizing the heavy metals contained in soils in a severely contaminated Italian mine site. Parallel experiments have been carried out in columns, one containing the soil as received, the other the soil mixed with fly-ash. The tests lasted for more than one year and the results obtained so far have shown that the heavy metal content of percolating waters can be drastically diminished when the soils are admixed with fly as
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