Better benches design enables to optimizes the risks of instabilities, to guarantee maximum of the ore recovery with minimum waste stripping. This requires detailed data on their geometric properties and the mechanica...Better benches design enables to optimizes the risks of instabilities, to guarantee maximum of the ore recovery with minimum waste stripping. This requires detailed data on their geometric properties and the mechanical properties of the materials (soil and rock), thus defining the appropriate means for investigation, modeling and numerical calculations. The objective of this article is to study the geotechnical behavior of slopes and edges of a mining pit under the influence of variations in the geometric parameters of the bench and mechanical parameters of the ground in the case of open-pit mines. To do this, we used the stability calculation software well adapted to landslide problems, called RocScience (Slide module version 6.020). Four geometric models were tested in order to assess the slopes and the mining pit edges stability, in order to choose the best model for the application of the different parameter’s variation. The stability calculations showed the influence of variations in the geometric parameters of the benches and the mechanical parameters of the soil on the factor of safety. The results of variations in favor of a decrease in the bench height, slope angle and an increase in the bench width show an increase in the factor of safety and vice versa. With the first three models, under static conditions all the factors of safety are greater than or equal to 1.4, which shows a state of satisfactory long-term stability, whereas under Pseudo-static conditions, the factors of safety are all less than 1, which means that collapse is inevitable with these models. It can be seen that with a fourth model whose geometric characteristics, the factors of safety obtained are greater than 1.5 in static conditions and 1 in Pseudo-static conditions, which shows of the slopes and pit edges long-term stability. As for the variations in mechanical parameters, the factor of safety increases with the increase of the mechanical parameters in static and Pseudo-static conditions. The sandstone layer showed inevitable instabilities with values of the internal friction angle below 40˚ and internal cohesion below 65 KPa. Instabilities are observed in the limestone layer with internal friction angle values below 35˚ and internal cohesion below 120 KPa. The pegmatite showed a state of guaranteed stability in an interval of the internal friction angle ranging from 30˚ to 35˚ and internal cohesion ranging from 250 to 300 KPa outside which instabilities inevitably occur. The variation of the parameters showed a very low effect on the last two layers due to the high values of the different parameters.展开更多
This study presents a novel method to evaluate the safety of open-pit slopes by means of three-dimensional numerical modeling with the finite difference method. The method presented here uses a block model as a vehicl...This study presents a novel method to evaluate the safety of open-pit slopes by means of three-dimensional numerical modeling with the finite difference method. The method presented here uses a block model as a vehicle to carry relevant information from the rock mass and automatically construct the numerical model. The results suggest that the method is promising because of its capacity to accurately incorporate a large amount of high-complexity rock data by considering spatial location and material behavior. It is expected that the innovations in this method will make the design, construction, and operation of open-pit iron mines safer and more economical.展开更多
This paper analyses microclimate parameters viz. rainfall, temperature, relative humidity, heat index, wind speed, wind direction, atmospheric pressure, dew point, air dust and air density around the Twangiza gold min...This paper analyses microclimate parameters viz. rainfall, temperature, relative humidity, heat index, wind speed, wind direction, atmospheric pressure, dew point, air dust and air density around the Twangiza gold mine, Eastern DR Congo. Results show that in previous decades, May did not use to be a dry month as it was an integral part of the shorter rainy season and September has become drier. This depletion of May and September rainfall is a change in the study region. A significant difference was observed between both septennia (2010-2017 and 2018-2024) regarding the second rainy season (B = February-May) only at one of stations. Significant differences occurred between both septennia regarding the dry season (June-August), with more rainfall in the second septennium (2018-2024). This confirms a microclimate change in the study area, even at a range of 3 - 10 km distance, indicating patchy rains. The values of temperature and heat index increased during the second septennium;e.g. 25.3˚C max dry season 2018-2024 vs 23.4˚C dry season 2010-2017;thus differences of 1.9˚C for temperature and 1.5˚C for heat index. This is an indicator of warming in the microclimate along the quindecinnial. The results show that the mine generates seven to ten times more dust when in operations due to moving equipment and other ancillary equipment. The residential and industrial guideline limits did not change even when the mine was operational. This study has the merit of illustrating the accuracy of the best regional climate change prediction models, such as the GIZ long-term forecast for the neighbor country, Burundi, which predicted the increase of rains in the rainy season, the depletion of rains in months leading up to the dry season (August/September), implying the prolongation of the dry season. They also noted a high probability that annual average air temperatures will gradually increase.展开更多
The Twangiza mine is located in the Mitumba mountain range, in the western part of the Albertine Rift Valley, just 20 km East of Itombwe Nature Reserve. A biological inventory was carried out within the mine’s decade...The Twangiza mine is located in the Mitumba mountain range, in the western part of the Albertine Rift Valley, just 20 km East of Itombwe Nature Reserve. A biological inventory was carried out within the mine’s decade-old progressive ecological rehabilitation sites. This inventory covered insects, amphibians, reptiles, birds and small mammals. The main objective of the inventory was to assess the level of animal recolonization in the 100-hectares’ restored areas. A total of 22 insect genera, 4 amphibian species, 11 reptile species, 43 bird species and 11 small mammal species were found. All of them were strongly settled in the core area within the afforested sites. Prior to the start of the Twangiza mine activities and 4 years before the ecological rehabilitation in the area, the avifauna was depauperate, both in number of species and their abundance. By then, no mammals or reptiles were recorded within the footprint area. The environmental and social baseline assessment identified 38 bird species in 2008, mainly grassland and mobile species, which were using scrub along valley streams as a refuge, outside the current mine footprint. Our results clearly demonstrate the positive impact of the afforestation on insect, amphibian, reptile, bird and small mammal’s diversity in this area.展开更多
It is essential to investigate the impact of tropical highland open pit gold mines on surface and groundwater quality and flow dynamics. Samples from the Twangiza gold mine, with long term mining activities, including...It is essential to investigate the impact of tropical highland open pit gold mines on surface and groundwater quality and flow dynamics. Samples from the Twangiza gold mine, with long term mining activities, including small-scale mining were analyzed in an accredited South African Laboratory. Results indicate that TDS and EC were higher in the mine site due the concentration of many metals. DO values were higher downstream. ORP and pH levels were similar at all site positions. Upstream: Fe, Si, K, Mg, Al have the highest concentrations (14.0 - 23.1 mg∙l−1). P, Pb, B, Ti, Sr, Ag, Ni, Ba, and As have concentrations ranging from 0.1 - 0.9 mg∙l−1. Li and Au have the lowest concentrations (0.01 - 0.05 mg∙l−1). Zn was also relatively abundant upstream, most likely airborne by the plant generator smoke. Within the mine site: Si, Al, Mg, Fe are found in higher concentrations (19 - 50 mg∙l−1). These are followed by K, As, and P (1.4 - 4 mg∙l−1). Ni, Ti, Ag, Sr, Ba are also found in lesser concentrations (0.2 - 0.7 mg∙l−1). The groundwater flow remained consistent. This study has the advantage of having continuously followed up a large number of heavy metals during years.展开更多
From a harmonized structural map at the scale of a portion of SW Burkina Faso (90 × 80 km2), we targeted prospective zones on the basis of structural criteria and structure-geology relationships. The map was cons...From a harmonized structural map at the scale of a portion of SW Burkina Faso (90 × 80 km2), we targeted prospective zones on the basis of structural criteria and structure-geology relationships. The map was constructed from an aeromagnetic image, and the geology was deduced from old geological maps. The procedure involved extracting the magnetic fabric and deducing the deformation gradients, which led to the identification of shear zones. Analysis and interpretation of the structural geometry of the obtained structural pattern led us to target areas of interference between structures or geology-structures interplays, which are conducive to the deposition of metallic elements. The subsequent overlay of known gold prospects and deposits documented in the region revealed the validity of the predefined prospects. This result reinforces the applicability of the methodology as a first-order regional approach to mineral exploration.展开更多
The main objective of this study is to determine the hydrogeochemical specificities of the groundwater of the Angovia mine operating permit, located in the Yaouré mountains in the center-west of Côte d’Ivoi...The main objective of this study is to determine the hydrogeochemical specificities of the groundwater of the Angovia mine operating permit, located in the Yaouré mountains in the center-west of Côte d’Ivoire. To do so, descriptive and multivariate statistical analysis methods with the SOM (Self Organizing Maps) algorithm were applied to the physicochemical parameters of 17 boreholes using the calcite (ISC) and dolomite (ISD) saturation indices. The results obtained have shown that the groundwater in the Angovia mine operating permit area has an average temperature of 27.52°C (long rainy season) and 27.87°C (long dry season) and has an average pH of 7.09 ± 0.35 during the main rainy season and 7.32 ± 0.35 during the main dry season. They are mineralized with an average electrical conductivity of 505.98 ± 302.85 μS/cm during the long rainy season and with 450.33 ± 233.74 μS/cm as average during the long dry season. The main phenomena at the origin of groundwater mineralization are water residence time, oxidation-reduction and surface inflow. The study of the relative age of the water shows that the groundwater in the Angovia mine operating permit area is mainly undersaturated with respect to calcite and dolomite. They are therefore very old in the aquifer with a slow circulation speed during the long rainy season and the long dry season.展开更多
The dual transmitter implements the equivalent anti-magnetic flux transient electromagnetic method, which can effectively reduce the scope of the transient electromagnetic detection blind area. However, this method is...The dual transmitter implements the equivalent anti-magnetic flux transient electromagnetic method, which can effectively reduce the scope of the transient electromagnetic detection blind area. However, this method is rarely reported in the detection of pipelines in urban geophysical exploration and the application of coal mines. Based on this, this paper realizes the equivalent anti-magnetic flux transient electromagnetic method based on the dual launcher. The suppression effect of this method on the blind area is analyzed by physical simulation. And the detection experiment of underground pipelines is carried out outdoors. The results show that the dual launcher can significantly reduce the turn-off time, thereby effectively reducing the impact of the blind area on the detection results, and the pipeline detection results verify the device’s effectiveness. Finally, based on the ground experimental results, the application prospect of mine advanced detection is discussed. Compared with other detection fields, the formation of blind areas is mainly caused by the equipment. If the dual launcher can be used to reduce the blind area, the accuracy of advanced detection can be improved more effectively. The above research results are of great significance for improving the detection accuracy of the underground transient electromagnetic method.展开更多
Surface stability is essential in underground mines health management systems. Unexpected Surface displacement in underground mines could lead to loss of lives, injuries, and economic losses. To reduce or neutralise t...Surface stability is essential in underground mines health management systems. Unexpected Surface displacement in underground mines could lead to loss of lives, injuries, and economic losses. To reduce or neutralise the adverse effects of surface displacement, it is vital to monitor and accurately predict them and unravel their mechanisms. In recent years, Convolutional Neural Network (CNN) and Long Short-Term Memory (LSTM) have proven effective in predicting complex problems. However, CNN neglects the dynamic dependency of the input in the temporal dimension, which affects surface displacement features. The Convolutional-LSTM model can dynamically learn the temporal dependency among input features via the feedback connections in the LSTM to improve accurate captures of surface displacement features. This study focused on evaluating the C-LSTM model in predicting surface displacement of underground mines and assessed the predictive capabilities and generalisation strength of using hybridised ANN models. Geodetic and geotechnical data gathered from a Gold Mine in Ghana was used. The three models were tested on experimental data collected at Monitoring Scan Point 3. It was observed from the prediction output that all the methods could provide applicable and practical results. However, using indicators like root mean square error (RMSE) and correlation coefficient (R) in assessing the output of the prediction, the C-LSTM had the best prediction output. This study contributes to the advancement of accurate and efficient prediction of surface displacement of underground mines, ultimately enhancing and assisting safety operations.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Better benches design enables to optimizes the risks of instabilities, to guarantee maximum of the ore recovery with minimum waste stripping. This requires detailed data on their geometric properties and the mechanical properties of the materials (soil and rock), thus defining the appropriate means for investigation, modeling and numerical calculations. The objective of this article is to study the geotechnical behavior of slopes and edges of a mining pit under the influence of variations in the geometric parameters of the bench and mechanical parameters of the ground in the case of open-pit mines. To do this, we used the stability calculation software well adapted to landslide problems, called RocScience (Slide module version 6.020). Four geometric models were tested in order to assess the slopes and the mining pit edges stability, in order to choose the best model for the application of the different parameter’s variation. The stability calculations showed the influence of variations in the geometric parameters of the benches and the mechanical parameters of the soil on the factor of safety. The results of variations in favor of a decrease in the bench height, slope angle and an increase in the bench width show an increase in the factor of safety and vice versa. With the first three models, under static conditions all the factors of safety are greater than or equal to 1.4, which shows a state of satisfactory long-term stability, whereas under Pseudo-static conditions, the factors of safety are all less than 1, which means that collapse is inevitable with these models. It can be seen that with a fourth model whose geometric characteristics, the factors of safety obtained are greater than 1.5 in static conditions and 1 in Pseudo-static conditions, which shows of the slopes and pit edges long-term stability. As for the variations in mechanical parameters, the factor of safety increases with the increase of the mechanical parameters in static and Pseudo-static conditions. The sandstone layer showed inevitable instabilities with values of the internal friction angle below 40˚ and internal cohesion below 65 KPa. Instabilities are observed in the limestone layer with internal friction angle values below 35˚ and internal cohesion below 120 KPa. The pegmatite showed a state of guaranteed stability in an interval of the internal friction angle ranging from 30˚ to 35˚ and internal cohesion ranging from 250 to 300 KPa outside which instabilities inevitably occur. The variation of the parameters showed a very low effect on the last two layers due to the high values of the different parameters.
文摘This study presents a novel method to evaluate the safety of open-pit slopes by means of three-dimensional numerical modeling with the finite difference method. The method presented here uses a block model as a vehicle to carry relevant information from the rock mass and automatically construct the numerical model. The results suggest that the method is promising because of its capacity to accurately incorporate a large amount of high-complexity rock data by considering spatial location and material behavior. It is expected that the innovations in this method will make the design, construction, and operation of open-pit iron mines safer and more economical.
文摘This paper analyses microclimate parameters viz. rainfall, temperature, relative humidity, heat index, wind speed, wind direction, atmospheric pressure, dew point, air dust and air density around the Twangiza gold mine, Eastern DR Congo. Results show that in previous decades, May did not use to be a dry month as it was an integral part of the shorter rainy season and September has become drier. This depletion of May and September rainfall is a change in the study region. A significant difference was observed between both septennia (2010-2017 and 2018-2024) regarding the second rainy season (B = February-May) only at one of stations. Significant differences occurred between both septennia regarding the dry season (June-August), with more rainfall in the second septennium (2018-2024). This confirms a microclimate change in the study area, even at a range of 3 - 10 km distance, indicating patchy rains. The values of temperature and heat index increased during the second septennium;e.g. 25.3˚C max dry season 2018-2024 vs 23.4˚C dry season 2010-2017;thus differences of 1.9˚C for temperature and 1.5˚C for heat index. This is an indicator of warming in the microclimate along the quindecinnial. The results show that the mine generates seven to ten times more dust when in operations due to moving equipment and other ancillary equipment. The residential and industrial guideline limits did not change even when the mine was operational. This study has the merit of illustrating the accuracy of the best regional climate change prediction models, such as the GIZ long-term forecast for the neighbor country, Burundi, which predicted the increase of rains in the rainy season, the depletion of rains in months leading up to the dry season (August/September), implying the prolongation of the dry season. They also noted a high probability that annual average air temperatures will gradually increase.
文摘The Twangiza mine is located in the Mitumba mountain range, in the western part of the Albertine Rift Valley, just 20 km East of Itombwe Nature Reserve. A biological inventory was carried out within the mine’s decade-old progressive ecological rehabilitation sites. This inventory covered insects, amphibians, reptiles, birds and small mammals. The main objective of the inventory was to assess the level of animal recolonization in the 100-hectares’ restored areas. A total of 22 insect genera, 4 amphibian species, 11 reptile species, 43 bird species and 11 small mammal species were found. All of them were strongly settled in the core area within the afforested sites. Prior to the start of the Twangiza mine activities and 4 years before the ecological rehabilitation in the area, the avifauna was depauperate, both in number of species and their abundance. By then, no mammals or reptiles were recorded within the footprint area. The environmental and social baseline assessment identified 38 bird species in 2008, mainly grassland and mobile species, which were using scrub along valley streams as a refuge, outside the current mine footprint. Our results clearly demonstrate the positive impact of the afforestation on insect, amphibian, reptile, bird and small mammal’s diversity in this area.
文摘It is essential to investigate the impact of tropical highland open pit gold mines on surface and groundwater quality and flow dynamics. Samples from the Twangiza gold mine, with long term mining activities, including small-scale mining were analyzed in an accredited South African Laboratory. Results indicate that TDS and EC were higher in the mine site due the concentration of many metals. DO values were higher downstream. ORP and pH levels were similar at all site positions. Upstream: Fe, Si, K, Mg, Al have the highest concentrations (14.0 - 23.1 mg∙l−1). P, Pb, B, Ti, Sr, Ag, Ni, Ba, and As have concentrations ranging from 0.1 - 0.9 mg∙l−1. Li and Au have the lowest concentrations (0.01 - 0.05 mg∙l−1). Zn was also relatively abundant upstream, most likely airborne by the plant generator smoke. Within the mine site: Si, Al, Mg, Fe are found in higher concentrations (19 - 50 mg∙l−1). These are followed by K, As, and P (1.4 - 4 mg∙l−1). Ni, Ti, Ag, Sr, Ba are also found in lesser concentrations (0.2 - 0.7 mg∙l−1). The groundwater flow remained consistent. This study has the advantage of having continuously followed up a large number of heavy metals during years.
文摘From a harmonized structural map at the scale of a portion of SW Burkina Faso (90 × 80 km2), we targeted prospective zones on the basis of structural criteria and structure-geology relationships. The map was constructed from an aeromagnetic image, and the geology was deduced from old geological maps. The procedure involved extracting the magnetic fabric and deducing the deformation gradients, which led to the identification of shear zones. Analysis and interpretation of the structural geometry of the obtained structural pattern led us to target areas of interference between structures or geology-structures interplays, which are conducive to the deposition of metallic elements. The subsequent overlay of known gold prospects and deposits documented in the region revealed the validity of the predefined prospects. This result reinforces the applicability of the methodology as a first-order regional approach to mineral exploration.
文摘The main objective of this study is to determine the hydrogeochemical specificities of the groundwater of the Angovia mine operating permit, located in the Yaouré mountains in the center-west of Côte d’Ivoire. To do so, descriptive and multivariate statistical analysis methods with the SOM (Self Organizing Maps) algorithm were applied to the physicochemical parameters of 17 boreholes using the calcite (ISC) and dolomite (ISD) saturation indices. The results obtained have shown that the groundwater in the Angovia mine operating permit area has an average temperature of 27.52°C (long rainy season) and 27.87°C (long dry season) and has an average pH of 7.09 ± 0.35 during the main rainy season and 7.32 ± 0.35 during the main dry season. They are mineralized with an average electrical conductivity of 505.98 ± 302.85 μS/cm during the long rainy season and with 450.33 ± 233.74 μS/cm as average during the long dry season. The main phenomena at the origin of groundwater mineralization are water residence time, oxidation-reduction and surface inflow. The study of the relative age of the water shows that the groundwater in the Angovia mine operating permit area is mainly undersaturated with respect to calcite and dolomite. They are therefore very old in the aquifer with a slow circulation speed during the long rainy season and the long dry season.
文摘The dual transmitter implements the equivalent anti-magnetic flux transient electromagnetic method, which can effectively reduce the scope of the transient electromagnetic detection blind area. However, this method is rarely reported in the detection of pipelines in urban geophysical exploration and the application of coal mines. Based on this, this paper realizes the equivalent anti-magnetic flux transient electromagnetic method based on the dual launcher. The suppression effect of this method on the blind area is analyzed by physical simulation. And the detection experiment of underground pipelines is carried out outdoors. The results show that the dual launcher can significantly reduce the turn-off time, thereby effectively reducing the impact of the blind area on the detection results, and the pipeline detection results verify the device’s effectiveness. Finally, based on the ground experimental results, the application prospect of mine advanced detection is discussed. Compared with other detection fields, the formation of blind areas is mainly caused by the equipment. If the dual launcher can be used to reduce the blind area, the accuracy of advanced detection can be improved more effectively. The above research results are of great significance for improving the detection accuracy of the underground transient electromagnetic method.
文摘Surface stability is essential in underground mines health management systems. Unexpected Surface displacement in underground mines could lead to loss of lives, injuries, and economic losses. To reduce or neutralise the adverse effects of surface displacement, it is vital to monitor and accurately predict them and unravel their mechanisms. In recent years, Convolutional Neural Network (CNN) and Long Short-Term Memory (LSTM) have proven effective in predicting complex problems. However, CNN neglects the dynamic dependency of the input in the temporal dimension, which affects surface displacement features. The Convolutional-LSTM model can dynamically learn the temporal dependency among input features via the feedback connections in the LSTM to improve accurate captures of surface displacement features. This study focused on evaluating the C-LSTM model in predicting surface displacement of underground mines and assessed the predictive capabilities and generalisation strength of using hybridised ANN models. Geodetic and geotechnical data gathered from a Gold Mine in Ghana was used. The three models were tested on experimental data collected at Monitoring Scan Point 3. It was observed from the prediction output that all the methods could provide applicable and practical results. However, using indicators like root mean square error (RMSE) and correlation coefficient (R) in assessing the output of the prediction, the C-LSTM had the best prediction output. This study contributes to the advancement of accurate and efficient prediction of surface displacement of underground mines, ultimately enhancing and assisting safety operations.
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.
