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By Hongsheng He, Xiaofang Lv, Jianfeng Wang

This paper provided an overview of characteristics of limonite ores as well as their influence on sintering performance. Evaluation experiments focusing on basic characteristics, granulation characteristics, and high temperature sintering characteristics had been conducted by using two types of limonite ores, then the principles of high effective utilization technology of limonite ores were discussed, and the sintering pot tests were conducted. Limonite ores possessed low total iron content, high combined water content, high SiO2 content, large average particle size, low adhering particles proportion, high porosity, high water absorption rate, short water absorbing time, poor granulation ability, high melt formation ability, low melt fluidity ability, low melt penetration ability, high melt absorption ability, low bonding phase strength, and high forming ability of SFCA. By taking the technical measures of ore-proportioning optimization, increasing the proportion of burntlime and segmentation granulation, the usage of limonite ores could reach 50% in sintering.

Aug 27, 2021

By Ali Behrad Vakylabad, Esmaeel Darezereshki, Babak Koohestani

As a by-product of the steelmaking industry rich in iron and zinc, electric arc furnace dust (EAFD) landfill disposal is restricted in many countries due to the metal lixiviation risks. Several approaches have been examined to recycle or reuse EAFD. Hydrometallurgical methods mainly include the preparation of pregnant acid leached solution (PLS) using inorganic acids followed by selective metal recovery using different methods. We herein proposed a hydrometallurgical process initiated by acid leaching and finalized by thermal treatment to produce nano-ZnO from EAFD. At the condition of this study, only 67% of zinc was leached by sulfuric acid from EAFD into PLS while 98% of surplus leached iron was removed through precipitation by sodium hydroxide. Additional purification of iron removed PLS was accomplished using di-2 ethylhexyl phosphoric acid to extract Zn+2. The addition of ammonium hydroxide to purified PLS provided (Zn(OH)2)3(ZnSO4)(H2O)5 as the final precursor for nano-ZnO that ultimately transformed to nano-ZnO (60 ± 6 nm particle size) at 850 °C. The achieved results were scrutinized through various tests and analyses including TEM, XRD, SEM, EDS, FTIR, and TGA.

Mar 10, 2021

By Y. Jinnouchi

An air-pulsated jig has been widely adopted as a main coal washer. It may be mainly because of its many technical and economic features such as large capacity, low running cost, long life, etc. However, the recent increasing demand of fuel coal requires a higher productivity and efficiency of the air-pulsated jig. To fill this requirement theoretical and experimental investigations have been conducted on model and practical jigs in Japan. This paper generalizes the results of these investigations. In jig operation it is essentially of the most importance to create efficiently the pulsation of the water best suited for coal washing. The optimum pulsation should be determined by the theory of jigging process, and the method to realize it by that of pulsating mechanism.

Jan 1, 1982

By Robert Burgess, Dale Gill, Jaco Steyn, Bill Kyslinger

"With mining, especially coal extraction, comes the necessity of supporting the roof. Since the 1950s, the primary method for roof support has been the use of roof bolts. Roof bolting is considered one of the most hazardous jobs in underground coal mining. In 2004, there were 3,405 injuries reported to the U.S. Mine Safety and Health Administration (MSHA). Of those injuries, 17 percent were associated with bolting machines (593 injuries). The majority of the injuries resulted from rock falling from supported roof. However, injuries involving a part of the body being struck by, or caught between, during bolting and drilling occurred with relatively high frequency (Burgess and Steiner, 2007).Roof drilling and bolt installation is labor-intensive and repetitive. These labor-intensive and repetitive requirements can lead to cumulative trauma. Operators are expected to perform a considerable amount of lifting, carrying, bending, reaching and stretching. Back and shoulders become sore from bending and twisting to install bolts or lift and position drill steels, wrenches and bolts. Confined operator spaces also contribute to difficult and awkward working positions for the operators (Cornelius and Turin, 1998).In South Africa, the majority of the roof bolting machines used are “man-in-position” style machines (Fig. 1). This puts the operator in close proximity to where the drilling and bolting process is performed. When proper operation procedures are followed, it has been proven to be a very effective, productive and safe system. The MSHA-certified automatic temporary roof support (ATRS), canopies and dust collection system of Fletcher bolters all provide the operator with unparalleled protection. However, there are some occupational hazards inherent to the zone located next to the drilling and bolting zone. This has led some customers to request relocating the operator away from this zone. The idea being that the operators will no longer be located in the face area, greatly reducing their exposure to dust, noise, machine and geological hazards."

Mar 1, 2017

By J. M. Link

A technique is presented for the economic selection of a slurry pipeline with the aid of a computer. Mathematical models for the flows of homogeneous slurries are utilized. Only the pipeline and its prime movers are considered. Slurry flow properties are first obtained from rheology and/or pipeline data measurements. A rheological model is then selected for the slurry. It must be emphasized that the accuracy of the method is greatly affected by the accuracy of the slurry flow-property data. Approximate cost parameters may be selected from data for plain and lined pipes, centrifugal and positive displacement pumps, motors and engines. Cost data for the purchase, operation and maintenance of slurry pipelines are also described. A total cost equation for the ownership and operation of a slurry pipeline system is then established. The complexity of the equation is a function of the rheological model selected to describe the slurry. The equation is solved with the aid of a computer for several combinations of pipeline diameters and throughputs to yield minimum total annual cost for the system. A mean velocity is then computed to give the required throughput. The velocity is constrained by an upper and lower bound. A high velocity is undesirable from an energy consumption viewpoint and if pipeline wear is possible. On the other hand, the velocity must exceed the deposition velocity for a heterogeneous suspension or the critical velocity for a homogeneous suspension. There is no guarantee that the velocity developed by this method will lie within the constraints applied, nor that the constraints are even known. This is particularly true for heterogeneous slurries. An important feature of the method is the ease with which the variables can be adjusted to measure the sensitivity of the total cost to the variables. The purpose of the sensitivity analysis is to identify those critical variables that. if changed, can considerably affect the total cost. Mathematically, individual variables are changed and the effect of such a change on the annual total cost is computed. But from a designer's point of view, individual components in the system are changed to study their effect on the annual total cost. A change in one component of the system may involve a change in one or more variables. For example, the replacement of a steel pipe by a smooth-lined pipe will change the pipewall roughness and wall thickness as well as purchase, operating, and maintenance costs.

Jan 1, 1974

By Gary Peach, Peter Mason

Planning and estimating progress rates and costs for tunnelling is always best done based on experience and historic precedent. Much precedent is available but the use of data monitoring, data mining and other retrieval techniques on modern TBM machines can enable this to be further expanded and refined. Advance rates can be related much more closely to rock types as can associated rock bolt and mesh/ shotcrete requirements. This in turn can lead to a further refinement in best likely combinations of equipment, such as shotcrete jumbos, better selected for the anticipated conditions, rather than the potential advance rates of the machine. Efficient and timely construction of the tunnel will also be linked to times needed for finishing work, such as contact and void grouting and to how this can be initiated while the TBM is still in operation, in order to save overall construction time. Indeed, this in turn may affect the most preferable layout and construction details of the permanent tunnel. Considerable experience has been gained in the use of two large diameter TBM tunnel drives through the Himalayas at the Neelum-Jhelum hydropower project in Pakistan. All the above aspects will be discussed in the paper based on the considerable experience and data which came from that operation, including appropriate measures in highly stressed areas potentially subject to rock burst.

Jun 13, 2021

By Neel Gupta, Dustin M. Crandall, Brijes Mishra

X-ray computed tomography (CT) images of rock specimens often contain artifacts which must be corrected before scientific analyses are performed. This paper presents a new workflow of automated image processing to utilize poor-quality X-ray CT scan images. The workflow runs on the open-source image analysis software and efficiently separates desired features from low-contrast scanned images. The new workflow is a two-step technique using contrast enhancement and automated feature segmentation to generate noise-free binary images. The results of binary images using the proposed workflow and using a conventional thresholding technique are analyzed to show the quality of the proposed method. The paper also presents a workflow of estimating the structural geometries of features in two and three dimensions. The results of the structural feature analyses and computational time were compared between the open-source (ImageJ) and commercial image analysis software (Bruker Computed Tomography Analyzer). The commercial software was more computationally efficient, but the task-specific macros in open-source software enabled the user-desired automation in image processing and data extraction of desired structural features of comparable quality.

Sep 8, 2022

By R. A. Pyper

Laboratory leaching experiments were conducted to ascertain the effectiveness of acidic solutions of thiourea, CS(NH2)2, for dissolving gold from finely disseminated gold ores. The ore tested was from the Chipmunk orebody of the Northumberland mining district in Nye County, Nevada, USA. Extractions of up to 90 percent were attained from the ore. Extraction was shown to be dependent on thiourea concentration, ferric sulfate oxidant concentration, acid concentration, and leaching time. Optimum conditions were an ambient temperature leach near pH 1.0 utilizing 100-200 kg/t thiourea and 50 kg/t ferric sulfate for 8 to 24 hours.

Jan 1, 1981

A methodology has been developed and demonstrated to be effective in reclaiming surface-mined land for a forestry post-mining land use. The forestry reclamation approach (FRA) has been applied, almost exclusively, to flat or gently rolling surfaces. One of the primary steps in the FRA is to loosely grade the top 1.22 m (4 ft) of soil or substitute root growth medium to avoid excessive compaction. Concern has been expressed by regulators and the public that loose grading on steep slopes (i.e., greater than 23°) could lead to slope failures, which is one of the issues that the Surface Mining Control and Reclamation Act of 1977 (SMCRA) sought to correct. A field investigation was conducted at a steep-slope contour operation in eastern Kentucky to test the applicability of FRA in this setting. Final grading was performed according to FRA standards. The surface consisted of two distinct substitute rooting media. One was unweathered gray sandstone and the other was a combination of gray sandstone, brown sandstone, and topsoil. A variety of native hardwoods was planted following the FRA guidelines. The slope was instrumented with 70 survey monuments to monitor for mass movement. The reclaimed spoil was also characterized using bulk density and penetrometer resistance methods. The characteristics of both spoils are similar to those observed on flat to rolling surfaces where the FRA has been used and, after one year, approximately 70% of the trees had survived. During this first phase of investigation, there has been no major mass movement of the slope and slope stability analysis indicates that the application of the FRA has little impact on the overall stability of the slope. Mining Engineering, 2011, Vol. 63, No. 12, pp. 55-62. Official publication of the Society for Mining, Metallurgy and Exploration, Inc.

Jan 1, 2011

By S. Tan

In this paper, several commonly used computer truck dispatching criteria are evaluated. A computer-oriented truck dispatching and production simulator was developed to provide data for comprehensive cross comparison among the dispatching criteria. The definitions, primary considerations, characteristics, and performances of these dispatching criteria were investigated. From the simulation results, it was concluded that, in general, no one criterion can dominate all others. All basic dispatching criteria including minimizing truck waiting time, minimizing shovel waiting time, minimizing truck saturation, maximizing truck momentary productivity, or truck routes optimization provide a local optimal solution. To obtain a direct global optimization solution for this complex stochastic process does not appear to be likely. Therefore, the search for an optimal dispatching criterion that will fit all conditions may not be realistic. However, based on the simulation results of the mine operation, several dispatching criteria which have good potential to increase performance can be selected. It may be necessary to search for the best combination of these truck dispatching criteria for a given situation. For example, a truck flow measurement such as the truck clustering factor at shovels can be used as a switch parameter to change from one criterion to another. The values for the switch parameter at which actions should be taken to change the criterion can be established through simulation programs.

Jan 1, 1992

By Donald C. Violetta

During 1963 more than 200 million tons of coal was consumed by the public utility industry. Ash residual, from the burning of this coal has caused disposal problems. In order to prevent air pollution, dust collection systems have been installed to suppress the fine ash emitted from boilers before it is discharged into the atmosphere. The collected ash, called fly ash, must be removed from the dust collection facilities and disposed in some manner, usually at a substantial cost to the utility. Many years ago fly ash disposal was not a serious problem because the demand for power was relatively low and coarse coal was burned on stoker type traveling grate machines. The low burning rates utilized on these grates did not produce large quantities of air-borne coal ash while the mechanics of this system of burning resulted in a clinkered residue of cinders. Both of these conditions resulted in the production of only small quantities of fly ash. As the demand for electricity increased, a method of burning pulverized coal was developed and was introduced to the public utility industry in 1918 at Milwaukee, Wisconsin.1 This method of firing was considered a significant advance in steam electric generation as it (1) permitted the use of coals that could not be economically fired by other methods and (2) has generally resulted in improved efficiency, greater generating capacity and lower costs.2 The utilization of larger generating units using pulverized coal substantially increased the quantity of fly ash which resulted in a' more severe disposal problem.

Jan 1, 1966

By J. Paraszczak

Underground metal mining involves many challenges. Economic slowdown, tough international competition and sometimes volatile metal prices put constant pressure on mine operators to increase productivity and to reduce production cost. At the same time, countries such as Canada, the United States and Australia are experiencing skilled labor shortages that might even stall development of certain mine projects. Furthermore, some stages of underground production take place in particularly hazardous environments where the safety and health of miners is at risk. Automation of some processes in underground mining is one of the promising avenues to alleviate some of these problems. Loading and haulage are among the most critical operations and areas where implementation of autonomous vehicles has been targeted. However, although health and safety issues are a primary driver to opt for automation, the latter should ensure an acceptable level of productivity and pro?tability. With this in mind, this article focuses on the factors affecting operational effectiveness of autonomous underground loading and haulage equipment and the means to maximize it.

By Lloyd B. Underwood

In the event of a sudden nuclear attack upon the United States, it is imperative that vital command and control centers have a high probability of survival. One such vital facility is the North American Air Defense Command Combat Operations Center at Colorado Springs, Colorado. Known briefly as NOW, this installation when completed will be housed in large chambers excavated out of granite beneath the eastern slope of Cheyenne Mountain (Figure 1). The NORAD COC, a U. S. Air Force sponsored project, will serve as the primary collection and evaluation center for data concerning unknown aircraft, missiles, or space vehicles, which might bring destruction to North America. The data will be fed into high-speed computers and electronic equipment from outpost sources - radar, ballistic missile early warning stations and picket ships throughout the world. Electronically controlled display boards will make it possible to evaluate the tracking data instantaneously and to take appropriate defensive action1.

Jan 1, 1965

By S. Al-Thyabat

In this work, the floatability of Jordanian phosphate slime (-38 µm) was evaluated in a batch column flotation cell, 100 cm high and 5 cm inner diameter. Flotation was conducted using sodium oleate as a collector and methyl isobutyl carbinol (MIBC) as frother. Rougher flotation yielded concentrate assaying 29.19% P2O5 with 90.29% recovery at the following flotation parameters: 2.6 cm/s superficial gas velocity, 20 ppm frother dosage, 0.205 mM collector concentration and 40% weight solids. It was also found that conditioning with the same collector dosage but with a different solids weight percent gave different flotation results. However, pulp collector concentration was the key operating parameter; increasing collector dosage at the same solids weight percent decreased flotation recovery by 3%, while increasing solids weight percent at the same collector dosage increased phosphate recovery by 18%.

Jan 1, 2011

By T. Cyrul

The Polish underground mining has its long lasting tradition. High production of coal, that has recently been approaching 200 milion tons per year, put this small country among the bigest world producers of coal. To achieve such a high production, which mainly originate from very unfavourable mining and geological conditions, Polish scientists and engineers have to introduce new and original solutions to the mining practice. Many of the solutions on mining methods, ventilation, stability, subsidence etc., have had the world wide reputation, however, insufficient translations from Polish cause , that many of the recent Polish mining achievements are not known to foreign specialists.

Jan 1, 1986

By Sean Masse

New Gold?s New Afton Mine, located 8 km (5 miles) west of Kamloops, British Columbia, is a 4.5-Mt/a (5-million stpy) block cave mine, making it the highest tonnage underground hard rock mine in Canada. The reserve is estimated at 52.5 Mt (55.9 million st) with grades of 0.65 g/t (0.02 oz/st) gold and 0.93 percent copper (2012). Commercial production was achieved in July 2012 and nameplate production was achieved ahead of schedule in September 2012, with the cave breaching to surface in 2013. The mill has a SAG and a ball mill with a froth flotation circuit.

Jan 1, 2014

By Ping Zhang, Shahram Mozaffari, Andreas Ylmefors

The risk associated with mining induced seismicity and the related rock bursts has become one of the major threats to the safety and sustainability of mining at the Kiirunavaara mine. The causes of mining induced seismicity at the Kiirunavaara mine are very complex and have affected our understanding on the source mechanisms of seismicity and further the mitigation of the seismic risk. Detailed analysis of historical mining induced seismicity at the Kiirunavaara mine was conducted. The focus of this analysis was placed on the classification of large seismic events and the evaluation of the influential factors on the classified seismic events. 145 events with local magnitude larger than 1.5 that occurred between January 1, 2011 and March 31, 2021 were analyzed. For this analysis, seismic events located in the hanging wall were not included, as these have not been observed to cause large damages to the mine itself. It was found that the magnitude of the events had good correlation with the stress change in relation to the production location. The seismic events were classified as mining-front associated, ore-pass associated, mining-front and ore-pass associated and others, according to their hypocenter location. Most of the mining-front associated events, concentrated around the production levels and slightly above and below them, generally correlated with shear cracks, and most of them occurred when the ore flow between two production levels started. The numerical modelling showed that slip of the geological discontinuity, due to unclamping between hanging wall and footwall, could be the major causative mechanisms, which further supports this finding. The ore-pass associated events are located close to the ore passes. Large seismic events located between ore passes have the source mechanism of both fault-slip and non-shear, but events located at the outer side of ore passes were all fault-slip type. By checking with the ore pass scanning data, it was concluded that the most of the events located between ore passes could be pillar bursts. An elastic core concept has been then used to define a critical pillar width. The paper is not intended to be prescriptive but rather to initiate discussion of the possible classification of seismic events at the Kiirunavaara mine and to present new perspectives of the causes of the seismicity for improving the present seismic risk management.

Apr 26, 2022

By J. Hart, P. W. Conrad, S. Rosenthal, R. A. Hogan

The Mining Engineering Department at Montana Technological University (Montana Tech) has a new Mine Safety and Health Administration (MSHA) approved program for Part 46 and Part 48 mine health and safety training. The training program will utilize the facilities and faculty from Montana Tech’s Mining Engineering and Safety, Health, and Industrial Hygiene departments to provide superior mine health and safety training to the mining industry. The faculty of each department includes professionals with experience in safety training and the mining industry. The training program incorporates adult learning techniques and extensive hands-on activities in all training modules. The instruction will exceed MSHA requirements. The resources available on Montana Tech’s campus will be utilized to strengthen the training program providing the mining industry with a world class mine health and safety training program.

Feb 1, 2023

By C. A. Rowland

With the rapidly rising cost for electrical energy and the long range pre¬dictions for continued rising costs and even possible energy shortages, operation of rod, ball, autogenous and partial autogenous grinding circuits to efficiently utilize the power delivered to the mills will be demanded. This calls for a method to evaluate grinding circuit performance that is accurate, reliable and readily usable as an operating tool by supervisory, technical and operating personnel. Neither the Rittinger and Kick theories of comminution,(1) which preceded the Bond Theory by more than 50 years, had a mathematical means that could be used to predict and evaluate the performance of crushers and grinding mills used to comminute ores and rocks. This severly limited the practical use of these two theories, which were contradictory to each other. They have been superseded by the Bond Third Theory of Commnution.(1)

Jan 1, 1976

By Christopher J. Farrow

This paper describes the grinding circuits installed at two remote sites in northern Canada. One is Cominco's Polaris Project at Little Cornwallis Island; a barge-mounted lead/zinc concentrator. The other is Echo Bay Mines' Lupin Project at Contwoyto Lake, 400 km northeast of Yellowknife, a gold mine, all components of which had to be flown to the site. Logistics and considerations of operating and maintenance presented challenges which were met by innovative design. The evolution of the grinding circuits is discussed. Both plants are operating at design throughput.

Jan 1, 1983