IRANIAN JOURNAL OF MINING ENGINEERING (IRJME)
Year:2019 | Volume:14 | Issue:43 |Papers Count:10

There are many researches and contributions on stress analysis of tunnel’ s roof and wall. But there is not enough research on invert stress analysis, especially in soft grounds. In this paper it has been tried to introduce an analytical model for prediction and calculation of invert up-lift pressure in soil and very poor quality rock mass. Figure 1 shows the problem under tunnel’ s structures. When the pressure is high tunnel designer must be considered an invert structure for control of instability under tunnel lining. The pressure can be occurred by swelling process in some rocks and soils with high value clay content when there is a variation in moisture. But this research has been focused on invert up-lift pressure just by field stress and geomechanics conditions. Stress concentration and pore pressure have been considered in the equilibrium limit analysis and Mohr-Columb failure criterion has been applied as a linear well-known formulation for soils and very jointed rock masses behavior.

Floatation behavior of apatite mineral from the surface and deep samples of polymetallic ores from Gharah-Aghaj Urmia was studied. Floatation experiments were performed in the form of an experimental design considering the pH, solid percentage, and collector consumption amount as variables, for two samples of mentioned surface and deep ores. Results of the experiments approved the feasibility of obtaining concentrate from both samples, but the qualities of concentrates are completely different and floatation behavior of apatite of deep sample is weaker compared with the surface sample. Analyzing the effect of variables on the resultant grade and recovery revealed that pH, solid percentage and collector amount have a negative effect on surface sample grade. However, in the deep sample, pH and solid content don’ t have a significant effect on grade and the effect of collector amount on deep sample grade is positive. After optimization of floatation conditions for both samples, at optimized conditions, for the surface sample after a rougher stage and 5 cleaner stages, a concentrate with a grade of 33. 23%% P2O5 and a recovery of 74. 80%, and for the deep sample after 6 cleaner stages, a concentrate with a grade of 28. 81% P2O5 and a recovery of 55. 01% were obtained. Characterization revealed that deep concentrate has calcite and Magnesio-Hornblende which floats along with apatite and prevents the increase of the final concentrate grade. On the other hand, results of elemental analysis by EDX showed that the amount of fluorine element in the deep sample is lower in comparison to the surface sample, which is a reason for the low floatation strength of deep sample apatite. Finally, it has been concluded that in the Urmia Gharah-Aghaj ore deposit, as the depth increases the floatation efficiency of apatite decreases.

Job creation is one of the important social impacts of mining, which can be considered covering many aspects. The number of new jobs created, the duration of employment, the acquisition of skills for employment in other mines, and the duration of work in inappropriate conditions (especially underground mines) can be attributed to the job creation opportunities created by mining in the region. In addition to the points mentioned above, mining has some positive social impacts, such as creating welfare facilities and improving the livelihoods of the people in the region, and aslo some negative impacts, for instance, the creation of social anomalies, or gender imbalance. So far, many researches has focused on the economic and environmental impacts of mining, but the third criterion of sustainable development, which is the community, has been neglected. In this paper, "choice experiment" method, a new method of the "stated preferences" approach, has been used to estimate the values of mining social impacts. In this study, the social impacts of mining have been investigated in two categories; employment, and other social impacts of mining. A questionnaire was prepared and the results of 780 responses for each section were used as input for STATA software after encoding and its appropriate pattern and respondents preferences according to the coefficients and pattern results. Based on the results of estimating conditional logit in the categories, Lagrange's ratio proved to be statistically significant, which shows a significant regression for the model. Also, according to the results, it can be said that for respondents, the number of jobs and desirability of the livelihood is of the greatest value, and they are willing to work longer in inappropriate conditions, provided that these conditions do not lead to social anomalies in their place of residence.

Iran is the fourth largest producer of dimension stone in the world, which owns nearly 9 percent of global production. On average, annual production of dimension stone is 14 million tons. Due to several problems such as lack of modern technology and machinery in quarrying and processing of dimension stone, lots of these resources are being disposed as waste. In this research, the strategic planning of Lorestan dimension stone processing Industry has been investigated using SWOT analysis. Firstly, the factors affecting this industry are identified in four categories of strengths, weaknesses, opportunities and threats, using experts' opinions in the mining sector. Then, 50 questionnaires about these factors (strengths, weaknesses, opportunities and threats) were prepared and distributed. Both traditional and modern methods were used to analyze the results and select the appropriate strategies. In the traditional method, the effect of each factor on the industry were determined and then the strategic situation of the dimension stone processing industry of Lorestan province was identified using the SWOT, EFE, IFE, IE matrices. Results showed that the suitable strategic plan for Lorestan stone processing industry is a defensive strategy.

First roof weighting interval in mechanized longwall mining is related directly to the applied loads on support system and thus, has important role on stability, safety, and continuity of operation. This paper presents an innovative approach based on cavability of immediate roof to estimate first roof weighting interval. Nine inherent parameters of roof strata and its surrounding environment which affect caving process were taken into account to develop a classification system, incorporating fuzzy hybrid multi criteria decision-making technique. Roof Strata Cavability index (RSCi) was defined as summation of ratings for all parameters. Subsequently, the relationship between RSCi and extracted volume until the first caving moment (i. e. the extraction height× panel width × first roof weighting interval) was determined using linear and non-linear regression models. Models were proposed and validated using the actual field data collected from different longwall panels around the world. Results indicated that the quadratic polynomial model gave a better performance in the estimation of first roof weighting interval, compared to the other models. It was concluded that the proposed approach is an accurate and flexible tool to estimate first roof weighting interval in longwall mining.

The oxidation of sulfide minerals especially pyrite is the main source of acid production in mine waste rocks. Other sulfide minerals including chalcopyrite, covellite, and galena may also be responsible for acid production. Huge waste rock dumps with high sulfide content may generate lot of acidic drainages as a result of oxidation and hydrolysis processes. Accordingly, acid production and neutralization potential of waste rocks were evaluated based on common Acid-Base Accounting (ABA) and Net Acid Generation (NAG) methods at dump No. 7 of Miduk Mine. The results of chemical methods were compared with the mineralogical studies. Mineralogical analyses including X-ray diffraction (XRD), scanning electron microscopy (SEM) and electron probe micro analysis (EPMA) were employed to comprehensively study primary sulfides and secondary minerals. There was a strong possibility to generate acid mine drainage (AMD) with very high metal content in dump No. 7. According to the results of NAPP and NAG pH, all samples were classified as potential acid forming (PAF). The lowest and the highest NAPP were detected in samples HB1 and HC1S (200. 08 and 654. 14 kgH2SO4/t, respectively). Regarding paste pH and NAG pH, all samples were categorized as extremely acid forming (EAF) and acid forming (AF) materials. Due to high pyrite oxidation, the share of sulfate sulfur was ranged between 1. 28 and 7. 28 wt. According to both hierarchical cluster analysis (HCA) and principal component analysis (PCA), pH has an important role in the dissolution of waste materials. In addition, there is a strong positive correlation between Fe, Pb and As; indicating that they may have similar sources of soluble secondary minerals in the rock material. The results of the present study could be applied in the prediction of AMD generation for mine waste management projects.

As the demand for mineral resources increases, the need to underground mining is promoted and due to technological advances, deeper deposits with lower grade mineralization are becoming valuable. In underground operations, it is common practice that each area is planned individually. As these techniques often ignore how designing and planning one section can affect other sections, , optimum individual planning fails to provide an overall optimum design. In recent years, there has been a growing interest in simultaneous optimization that may assist with integrating different areas of the mine planning process and providing more profitable mines plans. In this paper, a mathematical IP model has been developed that simultaneously optimizes stope layout designs and production schedules for sublevel stoping (SLS) iron ore operations, and it is demonstrated that an integrated scheduling method can produce the globally optimal scheduling result by taking into account all interactions that occur across the stope layout optimization and scheduling. In this case, the application of the optimal integrated scheduling approach increases final NPV by 16 percent in comparison with the isolated approach.