نشریه مهندسی منابع معدنی
سال هفتم شماره 1 (بهار 1401)

High gas volume is the main reason of explosion, rock burst and fatal coal mining disasters. In a coal mining project, it is necessary to model the gas volume at all parts of the target seam. Amoung coal resources of Iran, Parvadeh I has high gas bearing seams with an average of 14 m3/t of gas. C1 coal seam is the main mining target in Parvadeh I and it was explored by 134 core drilling boreholes. Gas study has been carried out for 35 boreholes, in only central and eastern parts of the deposit. Gas volume is not measured at the deep western parts. In this study, fractured zones are identified and their gas data removed from the gas modelling procedure. It is found that gas volume and seam depth are highly correlated and also, two separated populations are evident in the gas vol. – depth cross plot. The first population is related to oxidized shallow, and the second one is interpreted as deep methane bearing zones of the seam. Using the regression kriging method with the seam depth as the auxiliary variable, the gas volume is estimated for the whole mining blocks of the C1 seam. The validity of the estimations is evaluated as 94% by the Jackknife method. In order to avoid the smoothing effect of kriging, the probability of critical gas zones (> 20 m3/t) is modelled by the conditional indicator cosimulation. Results demonstrated that 1.43 million m2 of the C1 seam with the probability of 75%, and 0.38 million m2 with the probability of 100% fell into the critical category. These critical gas zones are located in central, southern and western Parvadeh I. These zones are considered to be the main targets for the future gas drainage studies.

Gilan-e Gharb region has been located in the west of Iran and it has special features in terms of geology. Remote sensing data (satellite images), geology, tectonics and mineral data sets of the region were used to prepare an innovative integrated method for the exploration of Gilsonite mineral. Effective criteria and sub-criteria in the exploration of this mineral were identified and evaluated according to the available exploration data. Afterwards, these criteria were weighted using Fuzzy Analytical Hierarchical Process (FAHP). Accordingly, the ideal positive and negative solutions were ranked using a Fuzzy TOPSIS method to prepare a mineral potential mapping (MPM) of Gilsonite in Gilan-e Gharb region. The product of this paper is a potential map used for optimal identification in the early stages of exploration of Gilsonite mineralization that reduces the time, cost, and risk of exploration. Finally, the field’s visit and investigation has been accomplished for the regions with a high potential of Gilsonite mineralization to evaluate the proposed method. The results showed that 82% of the identified points had proper adjustment to the MPM. This high adaptation showed that the proposed method has good performance in Gilsonite exploration.

Selection of training sites is an important and critical undertaking in the modeling procedure of mineral exploration targets using artificial intelligence approaches. This is because application of improper training algorithms results in exploration targeting models that carry bias and uncertainty. The present study aims to model exploration targets of porphyry copper mineralization in Chahar-Gonbad area, Kerman province, Iran, using artificial neural networks. In this regard, continuous weighted evidence maps of exploration criteria including proximity to intrusive contacts, fault density, multi-element geochemical signature and proximity to iron-oxide and argillic alterations were generated and applied as inputs to the neural network. Subsequently, 16 points with known mineral deposits and 16 points without mineralization were used to train the neural network through extreme learning algorithm. The ensuing exploration targeting model was compared with a model obtained by using geometric average integration method through prediction-area plot. The overall efficiency of the models are 0.34 and 0.27, respectively. Evaluation of the models demonstrated that the areas with high copper mineralization potential, marked as exploration targets, are in good conformity with known copper occurrences as well as with geological indicator features. Thus, the targets can be planned for further exploration programs.

One way to improve oil production capacity is to use ultrasonic waves. Series of straight and ultrasonic stimulated water–flooding experiments were conducted on a long unconsolidated sand-pack using ultrasonic transducers because of a limited understanding of the mechanisms involved in applying ultrasonic waves as an enhanced oil recovery method. Kerosene and vaseline were used as non-wet phases in the system with a viscosity of 0.99 and 22 cp, respectively. Moreover, fluid flow and temperature rise experiments were conducted using an ultrasonic bath to enhance contributing mechanisms. They were carried out to observe the effects of ultrasonic waves on oil recovery. As a result, the recovery of water-flooding increased by about 16%. Furthermore, three mechanisms of improving oil production capacity were recognized: emulsification, cavitation, and viscosity reduction. The changes in pressure and ultrasonic velocity were also simulated using Comsol software alongside the sand-pack. As a result of the function of ultrasonic waves, this study can help the contributing mechanisms for improving oil recovery.

One of the most critical issues in weak grounds is soil improvement, which is considered reused in a new geotechnical structure or improves the current structure condition. In the present research, implementing a limited, finite element numerical method to predict the rate of ground settlement level before and after the implementation of ground improvement in the eastern access tunnel drilling process of Khorasan Square Station located in Tehran Metro Line 6. Since the tunnel route passes under residential buildings and shops, with the excavation of this part of the Khorasan Square Station project, large amounts of settlement exist on the ground surface, which cracked buildings and shop structures. Based on this, piling, fore poling, and anchoring improvement methods can be used for loose and fallen grounds that were modeled numerically by MIDAS GTS NZ software. In this research, in addition to investigating the performance of the mentioned methods, the effect of geometric parameters, including the covering of fore poling pipes, pile length, and the diameter of anchors, was investigated. The criteria for investigating, the Displacement occurred at ground level, and tunnel crown is considered. Results showed that all methods have been useful in reducing ground settlement and tunnel crown. Also, Among the above-mentioned improvement methods, the method of using the fore poling method with anchorage has reduced the plastic points surrounding the tunnel and also has a greater effect in reducing the settlement of the ground, so that it has reduced the maximum settlement of the ground surface by 50%.

One of the major problems related to blasting operations in open-pit mines is the formation of cracks on the benches behind the last row of blast holes or back breakes. Power Deck blasting has been introduced as a new and alternative method for conventional blasting, which improves blasting results by explosive energy utilization enhancement. In this technique, there is an air deck at the end of the blasting hole which decreases or eliminates sub-drilling. Power Deck blasting reduces charge per delay in the same conditions as conventional blasting and charge per delay is one of the most effective parameters of back break. In this study, back break caused by conventional and Power Deck blasting was evaluated in the Mishdovan iron ore mine. Back break in Power Deck blasting was reduced by 16.4% and 55% in iron ore and stone waste respectively as compared to back break in conventional blasting. Power Deck blasting could therefore be effectively used as a controlled blasting technique to obtain stable faces. Also after loading and hauling the fragment size, it was found that both methods have no significant differences in flat floors. Eventually, the Power Deck method reduced powder factor and specific drilling by 28.5% and 9%, respectively. In addition, holes productivity improved by 9% in Power Deck blasting compared to conventional blasting.

While many studies have confirmed the effect of particle size distribution on the residence time in a reactor, the most employed models of continuous tank leaching process consider the residence time and particle size distributions as independent variables. In minerals processing field, no systematic study has been conducted on this issue yet. In this research, the relationship between the particles size and their residence time in a mixing tank has been studied. An empirical method for the determination of the residence time distribution function based on the inflow particles size distribution has been proposed. The relationship between the average size of one size fraction of particles and its residence time was obtained by mean residence time and parameter  (an empirical coefficient). Results showed that increasing the particle sizes resulted in a 50% increase in the mean residence time while  decreased from 0.95 to 0.3. Using the evaluated values of  the residence time distribution function of the inflow stream was determined. Including this function in the segregated flow model, the effect of the variations of the  value on the leaching performance was evaluated. Results showed that smaller values of  resulted in higher conversion value.

Hydrocyclone is one of the main important equipment applied for the classification of materials in mineral processing plants. Presence of coarse particles in the hydrocyclone overflow adversely affects the performance of the downstream processes. This research was carried out to provide a solution for these problems by using vibrational wave analysis. The results of vibrometer analysis showed that the average rate of vibrational signal increased from 6 dB at normal condition to 11 dB at the chock condition and variation increased more than 2 times. To stabilize the hydrocyclone vibratory behavior, a rubber layer was fitted under the hydrocyclone base and tightened with an equal torque. In order to reduce the cost and increase the accuracy of the work a piezoelectric sensor was manufactured and installed by designing the printed circuit board and installing an alarm. Analysis of piezoelectric sensor data showed that the average vibrational amplitude increases from 13 dB at normal time to 23 dB during clogging. The size distribution results showed that the amount of K80 (the size at which 80% of the particles are smaller) increased from 119 microns under normal conditions to 725 microns during clogging due to the miss classification of materials transferred to the overflow. This result indicated by using these sensors the efficiency of mineral processing circuits increases significantly.

In the electrolytic extraction of zinc, the filter cake of the hot filtration process contains zinc, manganese, and cobalt. In this study, the metals were extracted by using two selective leaching steps. The results showed that at pH = 1 and 90 °C, about 88% of zinc was recovered without cobalt and manganese. In the selective leaching stage, cobalt was significantly extracted (91%) by adding hydrogen peroxide (H2O2) to the acidic leaching solution at pH <1. By reprecipitation of the extracted cobalt and selective leaching with H2O2, the solution containing cobalt ions with high purity was obtained.

Comminution is the most energy intensive operation which constitutes the major portion of operating and capital costs of the mineral processing plants.  Working at the maximum operating capacity of comminution equipment plays a significant role in the efficiency of the circuit.  Also, due to the effect of crusher efficiency on the downstream circuit performance, optimization of the crushing circuits has received considerable attention.  In this research, the effect of feed chute design on tertiary cone crusher performance at the Sarcheshmeh copper complex was studied.  A close monitoring of the performance crusher revealed that main problems were high fluctuations of power draw and uneven and high-rate wear of crusher liners.  Such pitfalls were clear evidences of an improper feeding arrangement into the crusher.  Accordingly, various feed chute designs were employed in the simulations by an in-house developed DEM software called KMPCDEM© to find more uniform feed distribution on the distribution plate of the crusher.  Results showed that by changing the shape of feed chute from cubic to cylindrical, decreasing its surface area from 0.34 to 0.24 m2 and increasing the cylinder length above and below the feed chute plate from 0 to 45 cm and from 53 to 95 cm, respectively, uniform feed distribution was obtained.  After installing the new feed chute design in the plant, a detail monitoring over a period of 15 months showed a reduction of the standard deviation of crusher power draw from 13 to 3 kW.  A better crusher control caused choke feeding.  Therefore, 36% increase in the crusher throughput and finer and narrower product size distribution occurred.  Furthermore, the life of crusher liners increased from 8 months to 15 months on account of more uniform and lower rate of wear on mantle and liners.