Mining industry has significantly contributed to the prosperity of the nation with economic growth, whereas mining operation has caused Acid Mine Drainage (AMD) with the abandonment of mines. As some researchers sugge...Mining industry has significantly contributed to the prosperity of the nation with economic growth, whereas mining operation has caused Acid Mine Drainage (AMD) with the abandonment of mines. As some researchers suggest, the history of AMD is, generally, affected by the change in not only mining industry but also in social and economic conditions. Thus, historical analysis is an effective way to find the key factors of AMD. In this study, in order to find the key factors of AMD, we examine the history of the United States (U.S.) and South Africa, where their economy had been developed owing to the large-scale mining, based on the findings in the previous studies. The results indicated that the abandoned mines due to the economic depression triggered AMD in the U.S. and South Africa. While the U.S. had progressively adopted anti-AMD methods in terms of prevention, prediction, and remediation (PPR) as a comprehensive approach, especially since the 1970s onwards because of the rise of environmental consciousness as well as strict regulations, South Africa is at the early stage of implementing the regulations following PPR. The public attention should be directed to environmental conservation in addition to the implementation of the regulations in South Africa. The improvement in socio-economic conditions is, additionally, necessary for the rise of environmental consciousness in South Africa in the light of the three pillars of sustainable development: social, economic, and environmental elements.展开更多
Acid Mine Drainage (AMD) which occurs when sulfide minerals are exposed to water and oxygen with an excavation is one of the serious environmental problems in the world. A dry cover system is generally constructed in ...Acid Mine Drainage (AMD) which occurs when sulfide minerals are exposed to water and oxygen with an excavation is one of the serious environmental problems in the world. A dry cover system is generally constructed in waste dump for the prevention of AMD in Indonesia by virtue of low cost and availability of waste rocks for a cover layer. However, the failure of the system caused by the lack of information related to the construction of cover system in mines, which leads to AMD, has been reported recently in Indonesia. In this study, the field investigation was conducted in pit and waste dump in open cast coal mine in Indonesia with the aim of obtaining the information on the construction of a cover layer and backfilling conditions of waste rocks in the waste dump. The rock samples taken in two areas of the mine were analyzed by geochemical analysis and sequential extraction with acids. The results indicated that Net Acid Producing Potential (NAPP) of the rocks in the waste dump down to 100 cm depth in both areas was from 10 to 30 kg H<sub>2</sub>SO<sub>4</sub>/ton, suggesting that Potentially Acid Forming (PAF) was backfilled in a cover layer. The backfill of PAF was contrary to the concept of cover system, which caused the failure of constructing a cover layer. The cause of the failure was likely attributed to the shortage of cover rocks which are classified as Non Acid Forming (NAF) or the failure of proper placement of them by an operational problem in the areas. Moreover, the results of the extraction with acids suggested that the form of iron and sulfur has to be taken into account to discuss the occurrence of AMD.展开更多
Oxidized and acidic mining discharges(pH between 4 and 5)from the Perkoa zinc mine in Burkina Faso consisting of waste rock,crusher rejects and mining tailings were sampled and used for neutralization tests with calca...Oxidized and acidic mining discharges(pH between 4 and 5)from the Perkoa zinc mine in Burkina Faso consisting of waste rock,crusher rejects and mining tailings were sampled and used for neutralization tests with calcareous dolomite(for six months).The mining discharges and the calcareous dolomite were previously characterized.Columns of 60 cm length and 15 cm diameter were used for the tests.Then,2.62 kg of calcareous dolomite was deposited on the mining discharges in each column.Two liters of deionized water are added every 15 days to each column.Samples were taken at the outlet of the columns at time intervals and then analyzed to assess the evolution of pH,electrical conductivity and contents of PHEs(Potentially Harmful Elements)over time.Following the neutralization tests on solid mining discharges,neutralization tests were also carried out on acid leachates resulting from the oxidation of these same solid mining discharges with calcareous dolomite.The results show that calcareous dolomite is very effective for the neutralization of SR(Sterile Discharges)and the precipitation of PHEs contained therein.It is also effective in buffering acidic effluents from these sterile discharges.As for other mining discharges(crusher rejects and mining residues),although calcareous dolomite is not effective in neutralizing these oxidized and acidic solid discharges,it is however effective in precipitating PHEs such as arsenic and lead.Calcareous dolomite is also effective in buffering acid leachates from these oxidized and acidic mining discharges(crusher rejects and mining tailings).展开更多
The improvement of microbial characterization has increased the comprehension of microbial population and their ability in the microbiological metal dissolution. Bioleaching processes have been expanded to use microor...The improvement of microbial characterization has increased the comprehension of microbial population and their ability in the microbiological metal dissolution. Bioleaching processes have been expanded to use microorganisms for the recovery of metals from ores and wastes. This study introduces Palca mine tailings pond in Peru which turned into acid mine drainage (AMD). AMD is a source of microbial communities whose microorganisms may support the aqueous extractive metallurgy for metal recovery. Four samples of AMD were collected from different locations and the elemental characterization showed concentrations of metals, such as Cu, Zn, Al, Mn, and Fe. The pH of the samples showed variation between 1.9 - 6.8. Twenty-one microorganisms were isolated and selected according the cell morphology. 16s rRNA gene sequences identified five species of which three belong to the bacterial kingdom and two to the Fungi kingdom. Two of the bacterial species were ferrous ion oxidizing bacteria, identified as Acidithiobacillus ferriphilus and Acidithiobacillus ferridurans;and the other one a ferric ion reducing bacteria identified as Acidiphilium acidophilum. The fungi species identified were Rhodotorula sinensis and Exophiala xenobiotica, a filamentous fungus isolated for the first time from an AMD.展开更多
文摘Mining industry has significantly contributed to the prosperity of the nation with economic growth, whereas mining operation has caused Acid Mine Drainage (AMD) with the abandonment of mines. As some researchers suggest, the history of AMD is, generally, affected by the change in not only mining industry but also in social and economic conditions. Thus, historical analysis is an effective way to find the key factors of AMD. In this study, in order to find the key factors of AMD, we examine the history of the United States (U.S.) and South Africa, where their economy had been developed owing to the large-scale mining, based on the findings in the previous studies. The results indicated that the abandoned mines due to the economic depression triggered AMD in the U.S. and South Africa. While the U.S. had progressively adopted anti-AMD methods in terms of prevention, prediction, and remediation (PPR) as a comprehensive approach, especially since the 1970s onwards because of the rise of environmental consciousness as well as strict regulations, South Africa is at the early stage of implementing the regulations following PPR. The public attention should be directed to environmental conservation in addition to the implementation of the regulations in South Africa. The improvement in socio-economic conditions is, additionally, necessary for the rise of environmental consciousness in South Africa in the light of the three pillars of sustainable development: social, economic, and environmental elements.
文摘Acid Mine Drainage (AMD) which occurs when sulfide minerals are exposed to water and oxygen with an excavation is one of the serious environmental problems in the world. A dry cover system is generally constructed in waste dump for the prevention of AMD in Indonesia by virtue of low cost and availability of waste rocks for a cover layer. However, the failure of the system caused by the lack of information related to the construction of cover system in mines, which leads to AMD, has been reported recently in Indonesia. In this study, the field investigation was conducted in pit and waste dump in open cast coal mine in Indonesia with the aim of obtaining the information on the construction of a cover layer and backfilling conditions of waste rocks in the waste dump. The rock samples taken in two areas of the mine were analyzed by geochemical analysis and sequential extraction with acids. The results indicated that Net Acid Producing Potential (NAPP) of the rocks in the waste dump down to 100 cm depth in both areas was from 10 to 30 kg H<sub>2</sub>SO<sub>4</sub>/ton, suggesting that Potentially Acid Forming (PAF) was backfilled in a cover layer. The backfill of PAF was contrary to the concept of cover system, which caused the failure of constructing a cover layer. The cause of the failure was likely attributed to the shortage of cover rocks which are classified as Non Acid Forming (NAF) or the failure of proper placement of them by an operational problem in the areas. Moreover, the results of the extraction with acids suggested that the form of iron and sulfur has to be taken into account to discuss the occurrence of AMD.
文摘Oxidized and acidic mining discharges(pH between 4 and 5)from the Perkoa zinc mine in Burkina Faso consisting of waste rock,crusher rejects and mining tailings were sampled and used for neutralization tests with calcareous dolomite(for six months).The mining discharges and the calcareous dolomite were previously characterized.Columns of 60 cm length and 15 cm diameter were used for the tests.Then,2.62 kg of calcareous dolomite was deposited on the mining discharges in each column.Two liters of deionized water are added every 15 days to each column.Samples were taken at the outlet of the columns at time intervals and then analyzed to assess the evolution of pH,electrical conductivity and contents of PHEs(Potentially Harmful Elements)over time.Following the neutralization tests on solid mining discharges,neutralization tests were also carried out on acid leachates resulting from the oxidation of these same solid mining discharges with calcareous dolomite.The results show that calcareous dolomite is very effective for the neutralization of SR(Sterile Discharges)and the precipitation of PHEs contained therein.It is also effective in buffering acidic effluents from these sterile discharges.As for other mining discharges(crusher rejects and mining residues),although calcareous dolomite is not effective in neutralizing these oxidized and acidic solid discharges,it is however effective in precipitating PHEs such as arsenic and lead.Calcareous dolomite is also effective in buffering acid leachates from these oxidized and acidic mining discharges(crusher rejects and mining tailings).
文摘The improvement of microbial characterization has increased the comprehension of microbial population and their ability in the microbiological metal dissolution. Bioleaching processes have been expanded to use microorganisms for the recovery of metals from ores and wastes. This study introduces Palca mine tailings pond in Peru which turned into acid mine drainage (AMD). AMD is a source of microbial communities whose microorganisms may support the aqueous extractive metallurgy for metal recovery. Four samples of AMD were collected from different locations and the elemental characterization showed concentrations of metals, such as Cu, Zn, Al, Mn, and Fe. The pH of the samples showed variation between 1.9 - 6.8. Twenty-one microorganisms were isolated and selected according the cell morphology. 16s rRNA gene sequences identified five species of which three belong to the bacterial kingdom and two to the Fungi kingdom. Two of the bacterial species were ferrous ion oxidizing bacteria, identified as Acidithiobacillus ferriphilus and Acidithiobacillus ferridurans;and the other one a ferric ion reducing bacteria identified as Acidiphilium acidophilum. The fungi species identified were Rhodotorula sinensis and Exophiala xenobiotica, a filamentous fungus isolated for the first time from an AMD.
