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The impact of a methane explosion on mining operations cannot be over-emphasized. The explosion is a result of rapid combustion when a methane/air mixture is ignited by an unexpected energy release, such as a mine fire, electrical arc or sparks caused by frictions or rock falls. In most cases, an ignition of methane/air mixture could result in a deflagration other than detonation. Resulting flames and overpressure induced by a methane deflagration will harm neighboring miners and local ventilation control devices.. ,It is essential that the mechanism of an explosion and associated destructiveness be fully understood. This research seeks to predict an influence region of an incident happened within a representative underground mine geometry. The most common geometric changes in an underground coal mine are bends, regulators/doors, obstacle in airways and changes in sectional area. These geometric changes could result in an attenuation of the flame and pressure wave as a result of a methane deflagration. A study of this phenomenon could enable mine planners to have better understanding of the over-pressure redistribution due to the explosion. Both numerical and experimental work has been done in this study to ascertain a better insight of this potentially devastating event. The experimental data are also used to validate the turbulence and combustion models used in this test.

Feb 23, 2014

By R. Schipper

Two bench scale biochemical reactors (BCRs) were operated over a period of 3 months for the removal of uranium, radium, and selenium from mining influenced water (MIW). A BCR is an anaerobic reactor comprised of organic and inorganic substrate including woodchips, straw, sawdust, and limestone. Uranium and selenium are removed in a BCR by biological reduction of oxidized species (i.e., selenite, selenate) to less soluble forms (Pahler et al. 2007, Blumenstein et al. 2008, Rutkowski et al. 2013). It is believed that radium may be removed through absorption to the biomass in the BCR. The bench scale BCRs were constructed of 6 inch PVC columns with a top to bottom flow configuration. The bench influent water consisted of three different water ratios from two adit seeps. BCR hydraulic retention times of 24 to 36 hours were targeted during the study. Influent concentrations ranged from 19 ug/L to 1.86 mg/L for dissolved uranium, 12 ug/L to 270 ug/L for dissolved selenium, and 4.9 pCi/L to 24 pCi/L for radium 226. The average and maximum dissolved uranium removal was 93.6% and 98.5% respectively, the average and maximum dissolved selenium removal was 93.3% and 98.9% respectively, and the average and maximum radium 226 removal was 89.5% and 100% respectively.

Feb 23, 2014

By H. EI-shall

Bench top centrifuge is used to study the consolidation behavior of phosphatic clays. A mathematical model (based on first order kinetics) is developed to describe the relationship between the void ratio (at any time) and the effective stress. Permeability of the sediment as a function of the void ratio is also described. The obtained data are compared with that obtained by other consolidation testing methods. Centrifuge results indicate that consolidation data may be developed in a short period of time (hours) as compared to days or weeks when other techniques are used.

Jan 1, 1995

By A. Janwong

Ion exchange technology is becoming more prevalent for metal recovery from low concentration solutions. The products of ion exchange are typically a metal free stream (product stream) and a concentrated metal stream (byproduct). The metals in the concentrate stream are usually precipitated and returned to the process or discarded. The unique features of emew® technology enable metals to be recovered directly from the concentrated stream. The advantage of the IX-emew® combination is the ability to have two product streams: 1) clean metal free solution and 2) metal product for sale. In addition to recovering metals from solution, it is also possible to separate metals from each other and recover more than one metal product. In this paper, examples of IX-emew® combinations are detailed including the recovery of copper, nickel and cobalt from an industrial waste stream, recovery of nickel from a spent electroless nickel plating solution and recovery of cobalt from an hydroxide cake.

Feb 23, 2014

By W. L. Price

I. INTRODUCTION Today, there are two conflicting trends facing the designer of the bulk material handling system. The first trend is the necessity to stockpile increasingly larger amounts of bulk material (coal, ore, stone etc.) as economically as possible. Fig. 1 illustrates such a typical large storage pile. The second trend is the increasing awareness of the ecological problems of today manifesting itself in a new concern over possible air pollution from storage pile surface particles. The conflict between these two trends can become dramatic when this bulk storage pile is located near a heavily populated area. Strong winds can easily create a severe local problem by blowing the particles from the pile surface toward residential and commercial areas, igniting a crisis in public relations. (2), (3), (4). To help define our combined subject and ecological culprit more accurately, Fig. 2 shows the commonly accepted size range of dust particles. A descrip¬tion of the present state-of-the-art of dust control for large storage piles is the intent of this paper. II. OPEN STORAGE PILE SYSTEMS - ALTERNATE CHOICES AND RELATIVE COSTS In discussing the open storage dust problem and possible solutions, one obvious question arises - what are the economics of placing large bulk storage under cover? Part or this answer will be found in Fig. 3 - an approximate unit capital cost comparison between several methods of storage. It will be noted that the cost curve(s) for the closed concrete silo storage illustrated in Fig. 4 is cheaper per ton at relatively small tonnage capacities, but as tonnage increases, the open pile storage unit cost (B) becomes more economical. Curve (T) covers the cost of open storage using the plow feeder arrangement shown in Fig. 5. A gravity draw-down pile with feeders at the base as shown in Fig. 6 represents yet another open storage choice.

Jan 1, 1972

By Jie Li, Longxiang Li, Wenbing Guo, Gaobo Zhao, Yuhang Hu

Surface subsidence caused by underground longwall mining is a very complicated process in time and space, influencing building and structures on the surface of the mining area, including houses, pipelines, and highway. The field monitoring data of surface subsidence are essential for protecting them. This study investigated the dynamic and residual subsidence characteristics of both the surface and the highway over a 730-day monitoring period on a longwall panel. Three monitoring lines (Lines 1–3) were established to monitor the subsidence process, and three stages were identified: initial stage of surface subsidence, active period of surface subsidence, and residual subsidence deformation stage. The maximum subsidence value on the highway (1,786 mm) was smaller than that on the surface (2,094 mm), and the maximum subsidence velocity on the highway (41.7–50.8 mm/day) was also lower than that on the surface (66.7 mm/day). During the residual subsidence deformation stage, both the surface and highway subsidence velocities decreased to below 0.6 mm/day. Furthermore, differences in subsidence characteristics between the surface and the highway were analyzed, with the subsidence value on the highway always being less than that on the surface, while the subsidence velocity during the residual deformation stage was not always lower. This could be attributed to the influence of dynamic loads from vehicles, which could induce additional residual subsidence on the highway. Further investigation into this phenomenon will be conducted in future research.

Jul 1, 2023

By Y. Guo, C. Cao

"China is rich in tungsten resource, but they are mainly associated minerals. The similar flotability of scheelite, fluorite, and calcite resulted in the difficult separation by flotation. This work summarized the current situation and the development of flotation reagents, technological process, and mineral processing equipments in China. Fatty acid served as the collector and water glass was the depressant to expand the flotability differences in traditional flotation technology. However the water glass inevitably influenced the flotation of tungsten minerals to a large extend, and the suppressed fluorite was difficult to recover by flotation. Abundant water glass lead to the bad settleability of the tailings and the tail water was difficult to circulate, resulted in serious environmental problems. Recent study proved that the selectivity of benzene armour hydroxyl oxime acid (BAHA) salts was adequate for the separation of tungsten minerals from fluorite, calcite and most silicate minerals without any depressant. By this way, sodium silicate was canceled completely in tungsten flotation, greatly improving the recovery of tungsten and the environmental problems caused by tail water treatment would be solved fundamentally. TUNGSTEN RESOURCES AND DISTRIBUTION IN CHINA China is rich in tungsten resources and the proved reserves accounted for 60% of the world's reserves [1]. However the wolframite has been dried up and the scheelite resources had become the main resource of the tungsten metal. Table 1 showed the most large and superlarge scheelite deposits in China. China has more than 40 large and superlarge scheelite deposits and the total metallic deserves is more than 3 million ton [2]. But most of the deposits were low-grade and the associated relationship was complicated. For example, scheelite was usually associated with wolframite, molybonite, bismuthinite, pyrite, fluorite, and calcite in Shizhuyuan and Yaogangxian mine."

Jan 1, 2016

By S. D. Abbott

Mines are filled with a mixture of gases, some of which are toxic, flammable, or explosive. Others serve as early reporters of impending problems. Mines monitor these gases in order to ensure the safe, efficient operation of the facility and avoid losses or disasters. Two different approaches to monitor these gases have historically been taken. One kind of device measures the amount of each gas present by using selective detectors (e.g. handhelds and spectrometers). Another kind separates the mixture of gases into the individual constituents, then measures the amount of each gas present (e.g. gas chromatographs). Handheld units are the most widely used, but gas chromatographs are the most powerful yet underutilized units available to enhance mining operations. There are many misconceptions about the nature, applicability and proper use of each type of device, and little data is available. Up to this point, many people had only the manufacturers? claims to guide them. This study was undertaken to clarify the range of applicability, important characteristics, and value in use of these units in real-world situations. An additional goal of the study was to provide ways to evaluate comparative data, and thus aid mining operations in choosing the most beneficial and reasonable ways to use such devices in various situations and contexts.

Feb 23, 2014

By Sidney A. Suhler

The persistent requirement for methods and equipment capable of detecting hazardous anomalies in advance of underground mining has led to the development by the U.S. Bureau of Mines of a directional radar probe. The probe operates from boreholes drilled from the surface into the underground region to be mined. The engineering model radar was completed in early 1982 and field demonstration tests were performed in May of that year at a selected coal mine. Preliminary in-situ electromagnetic tests were performed at several candidate coal mines to evaluate the radio-frequency characteristics of the coal. A coal mine in New Mexico was selected on the basis of low EM propagation losses in the coal and the presence of an extensive coal seam displacing fault as a radar target. The borehole radar was operated in two vertical boreholes which intersected the coal seam at approximately 25 and 40 feet from the fault interface. Radar reflections from the coal/ rock interface were detected in both tests. Underground tests in a horizontal borehole in the coal were less successful because of interfering reflections. Additional borehole-to-borehole tests were performed with a separate ground penetrating electromagnetic system to obtain radar range calibration data. The coal was found to be bounded by very lossy roof and floor sandstone and shale while propagation through the coal seam was obtained at distances up to 175 feet between test boreholes. Coal seam continuity was indicated by the hole-to-hole experiments through a section of the seam previously thought to be completely cut off by the fault.

Jan 1, 1983

By R. Asamoah, P. Forson, W. Skinner, M. Zanin

Despite the seeming benefits decoupling pyrite and arsenopyrite minerals present in practice, little success has been achieved. The present study presents possible process routes for attaining selective flotation broadly capitalizing on differential oxidation between these minerals, and the use of a chelating collectors. The best performance was achieved with dithionocarbamate application following copper activation, yielding 81.4% arsenopyrite and 37% pyrite recovery. Preaeration followed by staged addition of xanthate produced 76% arsenopyrite and 31% pyrite recovery while reverse flotation of pyrite after H2O2 addition gave rise to rejection of 66% pyrite accompanied with 24% arsenopyrite.

Mar 2, 2022

By Kelly F. Bailey

Introduction On June 20, 1986, the Occupational Safety and Health Administration (OSHA) published revised asbestos exposure standards for general industry and construction. The standards reflect OSHA's attempt to adequately control workplace exposures to minerals it considers carcinogenic - minerals capable of causing or contributing to cancer. These standards specifically identify asbestos as: chrysotile, an asbestiform serpentine mineral; and the amphibole minerals amosite, crocidolite, tremolite asbestos, actinolite asbestos, and anthophyllite asbestos. Each of these has a more common nonasbestos mineral analog that exists in nature in a crystalline, blocky shape rather than the hair-like or fibrous shape of asbestos. The mineralogical names for three of these nonasbestos minerals are unique: antigorite for chrysotile, cummingtonite-grunerite for amosite, and riebeckite for crocidolite. The other three nonasbestos analogs do not have unique mineralogical names. They are simply designated as actinolite, tremolite, and anthophyllite without the word asbestos following their names. The 1986 OSHA standards not only cover exposure to the six asbestos minerals, they also cover specifically the nonasbestos forms of actinolite, tremolite, and anthophyllite (AT&A). The new standards regulate these minerals exactly like asbestos (OSHA, 1986). The construction aggregate industry views this as a major problem because these nonasbestos minerals are common amphibole rock-forming minerals in the earth's crust. They exist in small quantities over large areas of the United States (Kuryvial et al., 1974). These minerals, unlike asbestos, are not mined for a specific commercial purpose. They are unavoidable components in much of the aggregate used for construction throughout the US. They are also common in the gangue material of metallic ores. There are areas of the US where amphibole-bearing bed¬rock is common. Not every rock mass in these areas contain amphiboles, however. It does mean, though, that amphiboles are physically compatible with many of the rocks in those areas. And given the correct geochemical conditions, they will be present primarily in the nonasbestiform variety. In addition, these amphiboles will probably exist in the natural drainage system, sand and gravel deposits, stream sediments, lake shores, valley basins, or ordinary beach sand within these areas. There has been little quantification of nonasbestiform AT&A in dusts and soils in the US. This is not surprising since these nonasbestiform minerals are not commercially valuable. However, an example of the pervasive nature of these minerals can be found in a 1981 Geological Society of America publication where about 0.7% tremolite-actinolite was found in the desert dust in and around Tempe, AZ (Pewe, 1981). Since OSHA standards treat these common nonasbestos minerals as carcinogens in the same way as asbestos, large natural areas in the US are implicitly being labeled as hazardous by OSHA. When a substance is identified as a carcinogen, another OSHA standard comes into play, the Hazard Communication standard. There are also right-to-know laws in 9 states that essentially duplicate this federal standard. These standards require that a product containing 0.1% or more of an OSHA-designated carcinogen be labeled as such (OSHA, 1983). This means that much of the stone and sand gravel products occurring naturally and mined in the US could be labeled a carcinogen when, in fact, they are not. The National Stone Association (NSA) and the domestic construction and mining industries believe that OSHA has seriously erred. The NSA has studied the health, mineralogical, technical, economic, and legal basis for OSHA's action. These studies concluded that there is no justification for the agency regulating nonasbestos minerals as if they were asbestos. Health issues The preamble to OSHA's 1986 asbestos standard states that evidence for asbestos-like health effects from exposure to nonasbestiform varieties of AT&A is inconclusive (OSHA, 1986). The fact is, not only are the data inconclusive, they are nonexistent. During 1986-1987, NSA's occupational health and epidemiology consultant, Environmental Health Associates (EHA), reviewed all available health studies related to AT&A. EHA found evidence that malignancies in both experimental animals and humans are associated with the asbestos forms of these minerals. No experimental or epidemiological evidence was found that indicated such pathogenic effects occur from exposure to nonasbestiform varieties of these minerals. There are relatively few scientific studies of the health effects of exposure to nonasbestiform varieties of AT&A. In three different animal studies, exposure to either nonasbestiform tremolite or actinolite did not result in pulmonary fibrosis on in excess tu-

Jan 11, 1988

By M. S. Moats, W. C. Hartzell

The stable domestic supply of gallium, indium, and germanium has been identified as a critical need for the United States. Electric arc furnace dusts, processed to recover zinc, produce a residue that could be a potential source of these critical materials. An industrial zinc leach residue was characterized to determine its particle size, chemical composition, and predominant mineral phases. Heated, atmospheric, agitated leaching using sulfuric acid and hydrochloric acid was examined to determine the extractions of gallium, indium, and germanium as a function of concentration and temperature. Extractions of gallium were found to be similar to iron in all experiments. The maximum percentage of Ga, Ge, and In leached into solution were 71%, 63%, and 48%, respectively.

Feb 1, 2023

By Laszlo Valentyik

The wide scale acceptance of the heavy media separation is due to its simplicity and efficiency. The two most important variables of the process are specific gravity and consistency of the medium. The latter is a function of the settling rate of the media solids. The almost always present clay in the feed and conse¬quently in the medium acts as a stabilizing agent, and its optimum concentration varied between 3-4%.(1,2) Since polymers essentially perform the same function in oil well drilling muds - i.e. to suspend cuttings during drilling - as the fine clay in heavy media separation, this led to the investigation of whether polymers could be used in heavy media separation as supporting agents. During the first phase of the work, it was found that by the controlled addition of polymers, the stability of the heavy media increased without unduly increasing viscosity of the suspensions, thus yielding conditions for more effective and efficient separation. The results of the experiments were reported in a paper at the AIME Centennial Annual Meeting, March 1971.(3) This paper presents the results of the experiment carried out during the second phase of the work.

Jan 1, 1975

By Neil D. Donnell, O&apos

Bituminous sands of the Lower Cretaceous McMurray Formation in northern Alberta constitute the ore for the surface mining operation at Syncrude Canada Ltd. These sediments represent a complex succession of fluvial, estuarine and marine depositional environments. Grade prediction is realized through a combination of geological interpretation, computer modeling, and reference to past mining experience. Accurate forecasts of feed grade permit reliable predictions of volumes for removal to meet budgeted synthetic crude oil production. This planning facilitates efficient allocation of mining equipment and resources. The feed grade to the Extraction Plant is monitored at various points along the delivery system.

Jan 1, 1984

By C. Cristoffanini

A real-time transient pipeline simulation was used to model the operational pressure response in the concentrate and tailings pipelines of the Minera Los Pelambres copper mine in Chile. A high-fidelity simulator was needed to train the operators on safe operation of the pipeline for different scenarios. A simulator that solves the transient equations was used to dynamically predict the pressure and flow throughout the pipeline to provide real-time responses to operational changes such as opening or closing a choke valve, or sending a water batch. Slurry rheological properties were incorporated into the model. This paper presents the technical background of the pipeline simulation model and the study of slurry properties. The paper shows the results of the transient simulation for different operating scenarios such as start-up, shutdown and leakage, by presenting the hydraulic gradient curves for each case. Finally, the paper briefly presents how the simulator was connected to an emulated control system and used to train the operator, it demonstrates the most effective tool available to learn to resolve undesirable conditions.

Feb 23, 2014

By R. K. Mehta

This paper presents the application of a simple genetic algorithm (SGA) to a coal slurry grinding process in order to find the optimum set of conditions under which the desired slurry properties can be attained. The operating parameters of the process were; slurry % solids, dispersant dosage, ball size, and mill speed. The optimization algorithm, which is based upon the mechanics of natural genetics, was used to find near-global optimum points specific to responses measured In terms of fineness, specific energy consumption, viscosity coefficient, and viscosity exponent. In order to minimize the viscosity of the slurry and simultaneously achieve a condition of maximum packing density, optimization was carried out by the penalty method using an overall objective function incorporating several responses. Computer results and analysis demonstrate the ability of the genetic algorithm to perform better than a traditional technique such as response surface methodology (RSM) and to rapidly locate "the global optimum".

Jan 1, 1992

By Huijun Shao, Qiang Liu, Zhengming Yi

The increase of the proportion of high Al2O3 content iron ore fine in iron and steel enterprises has brought about a series of problems such as the increase of the viscosity of blast furnace slag and the difficulty of the separation of slag and iron. In order to solve this problem, the effect of increasing MgO content on the technical and economic index, the cold strength, and metallurgical properties of high basicity and high-alumina sinter was studied through sinter pot test. Nova400NanoSEM field emission scanning electron microscope was used to analyze sinter microstructure. The experimental results show that when the MgO content fraction in the sinter with high basicity and high aluminum increases from 1.72 to 2.49%, the vertical sintering speed decreases by 4.38mm/min, the utilization coefficient decreases by 0.51t/(m2 h), and the low-temperature reduction degradation index increases by 6.7%. When MgO content in sinter is 2.11%, drum index and reducibility index are the highest, reaching 61.93% and 86.39% respectively. Mg2+ is mainly solid dissolved in the magnetite lattice and replaces Fe2+, up to 3.64%. The generated magnesie-containing magnetite inhibits the phase transition from Fe3O4 to Fe2O3 oxidation process in the sinter cooling process, which reduces the generation of secondary hematite and is conducive to improving the low-temperature reduction degradation performance of sinter.

Jul 4, 2021

By J. L. Carr

On average, one to two fatalities occur every year when a miner is struck or pinned by a continuous mining machine (CMM). Proximity detection systems offer an effective means to prevent these types of injuries and fatalities by sensing the presence of a miner and automatically disabling machine motion. The Mine Safety and Health Administration (MSHA) is expected to finalize a regulation that would require the use of proximity detection systems on all CMMs. Approximately one-fourth of all CMMs in use in the United States are already equipped with such a system. The use of these systems will save lives, not only by automatically preventing accidents but also by acting as a tool for educating miners and reinforcing safe work practices. Researchers at the Office of Mine Safety and Health Research (OMSHR) have conducted a series of field evaluations to quantify the performance of these systems in an underground coal environment. These field evaluations measured the distance at which the warning and stop zones were activated. The technology provided consistent activation of the warning and stop zones under many of the conditions tested. However, some performance inconsistencies were observed which present opportunities to improve the reliability of proximity detection system technology. Some of the notable variables that caused significant changes in performance and should be considered in the design, implementation, and use of proximity detection systems include interaction with the trailing cable, performance changes during tramming, and orientation of the miner-worn component.

Feb 23, 2014

By James B. Loftis

The importance of increasing the world's mineral production to help solve our food and energy problems has been widely discussed. Improved surface mining methods will be needed to meet these needs. This paper reviews the modern horizontal drilling and blasting methods which can increase the productivity and lower the costs of I surface mining. A substantial decrease in the number of blast holes required, total footage of blast hole required and amount of explosive used has been realized by many mining companies using this method. Applications of this method are presently in large coal surface mines. However, similar gains are possible and probable in open pit mining of copper and iron.

Jan 1, 1975

By R. R. Guzman

In this study, the "Mine Project Risk Management" methodology, MPRM (Botin et al. 2011), has been applied to characterize the sources of uncertainty and to quantify risk in the mining engineering stages of Block Caving mining method. As the result, rock mass caveability and ore fragmentation were identified as the two most relevant parameters of this process and a methodological model has been developed to quantify the risk associated to each of these two parameters. Furthermore, the applicability of the proposed model has been validated using as a case study the Chuquicamata Underground Mine Project in Chile.

Feb 23, 2014