International Journal of Mining & Geo-Engineering
Volume:46 Issue: 1, Winter and Spring 2012

In this study, the possibility of producing coal with less than 11% ash from tailings of flotation process was investigated. The effect of six flotation parameters: collector type, collector consumption, frother type, frother consumption, pulp density and mixing rate were studied on a sample from a tailing dam. A software based experimental design approach (DX7) was applied to determine and model effective parameters as well as flotation optimization through fractional factorial. It was shown that collector type and flotation machine mixing rate were the most effective parameters on ash content of concentrate. The results indicated that the production of a desired ash content concentrate, i.e. <11% was feasible. It was also shown that at the optimum conditions of experiment, production of a concentrate with about 10% ash content, and 12% weight recovery would be possible.

In this study, the possibility of producing coal with less than 11% ash from tailings of flotation process was investigated. The effect of six flotation parameters: collector type, collector consumption, frother type, frother consumption, pulp density and mixing rate were studied on a sample from a tailing dam. A software based experimental design approach (DX7) was applied to determine and model effective parameters as well as flotation optimization through fractional factorial. It was shown that collector type and flotation machine mixing rate were the most effective parameters on ash content of concentrate. The results indicated that the production of a desired ash content concentrate, i.e. <11% was feasible. It was also shown that at the optimum conditions of experiment, production of a concentrate with about 10% ash content, and 12% weight recovery would be possible.

Toppling failure is one of the most common modes of failure of rock slopes in layered rock strata. Flexural toppling is one of the well-known modes of the failure. This type of failure occurs due to bending stress. In this article, a brief yet comprehensive review of toppling failure is presented. Firstly, the conditions and general mechanism of the failure are described. Then, experimental, theoretical and numerical modeling of the failure is summarized. Next, several case histories are analyzed and the results with the existing theoretical models were compared and presented. Finally, some practical recommendations as how to use these models are made.

A brief background to the development of the rock engineering design process is given, showing that since the development of the science of mathematics, deterministic methods have been used to perform various calculations. The variability of rock properties and support characteristics have always been known. However, they were not explicitly used in design but compensated for by the use of a safety factor, i.e. making a design more stringent than required by the calculations. The problem with this procedure is that the effect of increasing a safety factor on the overall stability of the design cannot be known because the range of variability is not incorporated in the design. The only way to overcome this problem is to make use of the science of probability. In doing that, the ranges of rock qualities are explicitly included in the design and the probability of failure is exposed. Examples of common rock engineering calculations in mining are provided, showing that the probabilistic designs are not difficult or time consuming to perform and yield much more useful outcomes than merely using a safety factor.

This paper discusses some of the fundamental considerations when managing mining slopes. The goal of management is to reduce all components that contribute to the geotechnical risk and by doing so reduce the risk to as low as reasonably achievable. The techniques and procedures suggested are not exhaustive; they represent a snapshot of some of the practical techniques the author has found useful for a range of scenarios.

Correct estimation of water inflow into underground excavations can decrease safety risks and associated costs. Researchers have proposed different methods to asses this value. It has been proved that water transmissivity of a rock joint is a function of factors, such as normal stress, joint roughness and its size and water pressure therefore, a laboratory setup was proposed to quantitatively measure the flow as a function of mentioned parameters. Among these, normal stress has proved to be the most influential parameter. With increasing joint roughness and rock sample size, water flow has decreased while increasing water pressure has a direct increasing effect on the flow. To simulate the complex interaction of these parameters, neural networks and Fuzzy method together with regression analysis have been utilized. Correlation factors between laboratory results and obtained numerical ones show good agreement which proves usefulness of these methods for assessment of water inflow.

Due to substantial effect of classification of resource models on future mine planning, one should come with an accurate method of estimation to guarantee that the minimum error is acquired in the estimation process. The known world class Cu-Mo deposit, Sarcheshmeh Porphyry deposit (central Iran) selected as the study area. The Hypogene zone of the deposit was chosen as the space in which estimation processes should be done. The mean value of Molybdenum and Copper extracted from the top part of this zone, where sampling operations have been done on a dense grid. The correlation coefficient of 0.45 allowed going through the process of interpolation. It was shown that taking account Cu as an auxiliary variable the interpolation process, the estimation had been improved. Simple Cokriging interpolation technique is applied and it was proved that using Cu, with mean value of 0.61 percent, as secondary variable will decrease the estimation variance of Mo interpolation which has the mean value of 0.022 percent. The chief influence of this reduction appeared when the resource should be classified. Only 1% decrease was obtained when Cu used as secondary variable, but in an industrial aspect it can be of great importance as a high number of voxels in “Indicated” class changed into “Measured” one. This led to 133 Mt more Mo-ore that were added to the previous “Measured” class blocks. Also, the transition zones where the changes in class of cells have occurred are identified; these zones are mainly the places where Mo has fewer samples than Cu.

AVO as a known methodology is used to identify fluid type and reservoir lithology in subsurface exploration. Method discussed in this paper, consists of three stages, including: Direct modeling, Inverse modeling and Cross plot interpretation. By direct modeling we can clarify lithology or fluid dependent attributes. Analysis performed using both P-P and P-Sv attributes. Inverse modeling deals with real data and is fed by the results of direct modeling to identify the light hydrocarbon (gas) zones. The main role of cross plot interpretation is to confirm the inverse modeling results and consequently increasing validity of performed analysis. Using Hodogram – cross plot, makes possible to identify hydrocarbon zone even in small scales. This methodology was applied in Gorgan Plain Southeast Caspian, northern Iran. It was concluded that: fluid factor, SIGN, and Poisson reflectivity are fluid dependent attributes. It was also defined that normal incidence reflectivity and P-wave impedance reflectivity are lithology dependent. Inverted sections of fluid-dependent attributes defined the existence two light hydrocarbon accumula- tion under the Tertiary-Cretaceous unconformity in the North Gorgan Plain. Two wet and gaseous zones are also confirmed by cross plot.

Acid mine drainage (AMD) containing high concentrations of iron and sulphate, low pH and variable concentrations of heavy metals leads to many environmental problems. The concentrations of Cu and Mn are high in the AMD of the Sarcheshmeh porphyry copper mine, Kerman province, south of Iran. In this study, the bio-remediation of Cu and Mn ions from acid mine drainage was investigated using two native fungi called Aspergillus niger and Phanerochaete chrysosporium which were extracted from the soil and sediment samples of the Shour River at the Sarcheshmeh mine. The live fungi was first harvested and then killed by boiling in 0.5 N NaOH solution. The biomass was finally dried at 60 C  for 24 h and powdered. The optimum biosorption parameters including pH, temperature, the amount of biosorbent and contact time were determined in a batch system. The optimum pH varied between 5 and 6. It was found that the biosorption process increased with an increase in temperature and the amount of biosorbent.Biosorption data were attempted by Langmuir and Freundlich isotherm models and showed a good match. Kinetic studies were also carried out in the present study. The results show that thesecond-order kinetics model fits well the experimental data. The biosorption experiments were further investigated with a continuous system to compare the biosorption capacities of two systems. The results show that biosorption process using a continuous system increases efficiency up to 99%. A desorption process was eventually performed in order to recover Copper and Manganese ions. This process was successful and fungi could be used again.