The main purpose of blasting in open pit mines is to produce the feed for crushing stage with the optimum dimensions from in situ rocks. The size distribution of muck pile indicates the efficiency of blasting pattern ...The main purpose of blasting in open pit mines is to produce the feed for crushing stage with the optimum dimensions from in situ rocks. The size distribution of muck pile indicates the efficiency of blasting pattern to reach the required optimum sizes. Nevertheless, there is no mature model to predict fragmentation distribution to date that can be used in various open pit mines. Therefore, a new framework to evaluate and predict fragmentation distribution is presented based on the image analysis approach. For this purpose, the data collected from Jajarm bauxite mine in Iran were used as the sources in this study. The image analysis process was performed by Split-Desktop software to find out fragmentation distribution, uniformity index and average size of the fragmented rocks. Then, two different approaches including the multivariate regression method and the decision-making trial and evaluation laboratory(DEMATEL) technique were incorporated to develop new models of the uniformity index and the average size to improve the Rosin-Rammler function. The performances of the proposed models were evaluated in four blasting operation sites. The results obtained indicate that the regression model possesses a better performance in prediction of the uniformity index and the average size and subsequently the fragmentation distribution in comparison with DEMATEL and conventional Rosin-Rammler models.展开更多
A quantitative research was conducted at Tschudi mine, Tsumeb, Namibia with its main drive being to determine the influence that density and blast parameters has on the performance of a blast. The factors that are mos...A quantitative research was conducted at Tschudi mine, Tsumeb, Namibia with its main drive being to determine the influence that density and blast parameters has on the performance of a blast. The factors that are most vital to the fragmentation process are classified into three namely: explosive parameters, rock parameters and blast geometry. Rock fragmentation is dependent on two main factors, the rock properties which are uncontrollable and the blasting parameters that can be manipulated to give maximum efficiency. The selected variable quantities, density, charge length, volume of blast and mass of charge per hole were recorded after observation, determined via laboratory testing or calculated from their known equations. The main objective is to develop a model to predict blasting performance, and this will be achieved with the use of the Kuz-Ram model. The proposed equation related mean expected fragmentation size (calculated using the Kuz-Ram fragmentation model) to the actual fragmentation. Blasting parameters namely: burden, spacing, and charge quantity that are not included in this study were measured or calculated on site to facilitate the inputs of the Kuz-Ram model. A specialized software package SPLIT Desktop was used to estimate the actual mean fragmentation by analyzing scaled images from the post blast muck pile. The Microsoft Excel regression analysis correlated the two intact rock properties with the blasting efficiency. The expected mean fragmentation and the actual fragmentation were then used to determine the blast performance, defined as the percentage ratio of the actual mean to the expected mean. The blast performance showed a good relationship with density (R2 = 0.81971), with performance of the blast reducing with an increase in density. The performance also dropped with increase in charge length. The blast performance and mass of charge/explosives per hole relationship showed a correlation of (R2 = 0.56195), but the results were disregarded. Lastly the volume of the blast had a direct relation to the blast performance (R2 = 0.80897) and it would be logical to state that, the two are directly proportional to each other.展开更多
文摘The main purpose of blasting in open pit mines is to produce the feed for crushing stage with the optimum dimensions from in situ rocks. The size distribution of muck pile indicates the efficiency of blasting pattern to reach the required optimum sizes. Nevertheless, there is no mature model to predict fragmentation distribution to date that can be used in various open pit mines. Therefore, a new framework to evaluate and predict fragmentation distribution is presented based on the image analysis approach. For this purpose, the data collected from Jajarm bauxite mine in Iran were used as the sources in this study. The image analysis process was performed by Split-Desktop software to find out fragmentation distribution, uniformity index and average size of the fragmented rocks. Then, two different approaches including the multivariate regression method and the decision-making trial and evaluation laboratory(DEMATEL) technique were incorporated to develop new models of the uniformity index and the average size to improve the Rosin-Rammler function. The performances of the proposed models were evaluated in four blasting operation sites. The results obtained indicate that the regression model possesses a better performance in prediction of the uniformity index and the average size and subsequently the fragmentation distribution in comparison with DEMATEL and conventional Rosin-Rammler models.
文摘A quantitative research was conducted at Tschudi mine, Tsumeb, Namibia with its main drive being to determine the influence that density and blast parameters has on the performance of a blast. The factors that are most vital to the fragmentation process are classified into three namely: explosive parameters, rock parameters and blast geometry. Rock fragmentation is dependent on two main factors, the rock properties which are uncontrollable and the blasting parameters that can be manipulated to give maximum efficiency. The selected variable quantities, density, charge length, volume of blast and mass of charge per hole were recorded after observation, determined via laboratory testing or calculated from their known equations. The main objective is to develop a model to predict blasting performance, and this will be achieved with the use of the Kuz-Ram model. The proposed equation related mean expected fragmentation size (calculated using the Kuz-Ram fragmentation model) to the actual fragmentation. Blasting parameters namely: burden, spacing, and charge quantity that are not included in this study were measured or calculated on site to facilitate the inputs of the Kuz-Ram model. A specialized software package SPLIT Desktop was used to estimate the actual mean fragmentation by analyzing scaled images from the post blast muck pile. The Microsoft Excel regression analysis correlated the two intact rock properties with the blasting efficiency. The expected mean fragmentation and the actual fragmentation were then used to determine the blast performance, defined as the percentage ratio of the actual mean to the expected mean. The blast performance showed a good relationship with density (R2 = 0.81971), with performance of the blast reducing with an increase in density. The performance also dropped with increase in charge length. The blast performance and mass of charge/explosives per hole relationship showed a correlation of (R2 = 0.56195), but the results were disregarded. Lastly the volume of the blast had a direct relation to the blast performance (R2 = 0.80897) and it would be logical to state that, the two are directly proportional to each other.
