Search Documents

By Panshi Xie, Yingyi Zhang, JIANJIE DUAN, Shenghu Luo

The most important safety aspect associated with great mining height in steeply dipping coal seam mining is the stability and control of the roof. When soft coal and hard gangue make up the immediate roof of a working face, the soft-coal interlayer plays a significant role in gangue damage and can cause problems such as roof collapse in front of the support, collapse of partial area supports and other problems that can affect the stability of the supports and the surrounding rock system. This study found that the first weighting step of a multigangue roof is larger than that of a nongangue roof, but periodic weighting steps are similar. The overburden collapse height is lower in a multigangue roof than in a nongangue roof due to the buffering and supporting function of the collapsed gangue. Failure of the coal interlayer is the key factor in the collapse of multilayer gangue. The limited load of the interlayer and maximum resistance of the support is concluded by the hard gangue and soft coal interlayer mechanical model. The maximum resistance of the support increased with the dip angle of the seam and burial depth. Certain measures are proposed to control the stability of the gangue roof, including zoning control of the mining height and resistance and advancing the support while maintaining roof contact, thus ensuring the integrity of the support and surrounding rock system.

By AMIT SHARMA, BIBHUTI BHUSAN MANDAL

This paper describes the vibration transmissibility characteristics of mining vehicle seats under dynamic conditions in an opencast iron ore mine. Magnitude and frequency contents of vibration signals on the seat floor as well as on top of the seats were measured to record the change during transmission. The conventional rigid seats were found to resonate at about 4 Hz, which coincides with the resonance of the human spine. The pneumatic suspension seats also proved to be more efficient in attenuating the overall vibration energy transmitted from the vehicle chassis to the human body.

By Anand Kumar, Debasis Deb, A. K. Mishra, M V. N. S. PRASAD.

In the Adriyala project, shield-leg pressure data from all shields and shearer location with time stamp from a mechanized longwall face are monitored and recorded in a surface computer. The data contain random noise due to power failure, leakage of legs, bad sensor readings, and other maintenance or geomechanical problems. An algorithm has been developed to detect mining cycle parameters such as setting and final pressures and duration of the cycle from these data for the analysis of periodic roof weighting phenomena. The intensities and persistence of periodic roof weighting are vital information for mine management to make judicious decisions on longwall operation.

By Brendan Demich, Brendan Macdonald, Timothy J. Orr, Jason Navoyski, Jennica L. Bellanca, William J. Helfrich

Recent advances in computing, rendering and display technologies have generated increased accessibility to virtual reality. Virtual reality allows for the creation of dynamic, high-fidelity environments to simulate dangerous situations and test conditions and to visualize concepts. Consequently, numerous products have been developed, but many of these are limited in scope. Therefore, U.S. National Institute for Occupational Safety and Health (NIOSH) researchers developed a virtual-reality framework, called VR Mine, to rapidly create an underground mine for human data collection, simulation, visualization and training. This paper describes the features of VR Mine, including mine generation, simulated networks, proximity detection systems, and the integration and visualization of real-time ventilation models.

By Wei Victor Liu, Omer Faruk Ugurlu, Chengkai Fan, Bei Jiang

Accurate prediction of truck productivity plays a pivotal role in improving the efficiency and profitability of openpit mining operations. This paper proposes a deep neural network (DNN) model to overcome the challenge of predicting truck productivity in openpit mines. The prediction model was built using eight variables and was optimized by considering different train-test split ratios, numbers of hidden layers and neurons, and activation functions. The proposed model’s performance was evaluated using various metrics and compared with other commonly used machine learning algorithms. The results showed that the proposed model outperformed traditional machine learning models by achieving higher prediction accuracy. Moreover, a single-variable sensitivity analysis showed that haul distance is the most influential variable for predicting truck productivity. This study marks a pioneering effort in employing DNN to predict truck productivity in openpit mining, signifying a notable advancement in the field.

Jul 1, 2024

By M. Morrongiello

The Kalgoorlie Consolidated Gold Mines Fimiston Open Pit is mining through a dense network of disused level workings and stopes of varied sizes and orientations. This study investigated the interaction between underground workings and the pit slope stability, in particular for the ultimate pit depth of over 600 metres. Parametric analyses were conducted on the structural and rock mass properties in order to provide realistic input. Several cases in both 2D and pseudo 3D using UDEC were modeled and analyzed to investigate the performance of the rock mass at various mining stages. The concept of equivalent property factor was also introduced to model the 3D behavior using 2D models. Based on the modelling results, the possible failure mechanisms and deformation of the pit walls were assessed. Factors of safety have been derived for the pit slope at different mining stages using the strength reduction technique. The modelling results agree well with pit performance monitoring results to date. The concept and results presented in this paper could be a useful reference for operations with similar circumstances and stress regimes.

Jan 1, 2005

By Jozef Descour, Kazunori Nishioka, David M. Neil

Designers, engineers, and contractors are using three-dimensional seismic tomography for geotechnical site investigations and during tunnel excavation for hard rock and soft ground applications. Utilizing multiple types of seismic signals produced by a TBM, drill, or impact breaker, the reflection of different velocity features are processed into a holographic image of the actual structure to be encountered. The Mill Creek Phase 3 alignment in Cleveland, Ohio, was imaged to define existing conditions along a 1,200-ft section of a proposed 6.1-m (20-ft) diameter CSO tunnel and, specifically, a zone of expected anomalous conditions where drilling was inconclusive. In Japan, Kajima Corporation used TRT™ to image a number of tunnels including the Fujikawa and Kanaya tunnels in a combination of methods to map structural features along the alignment.

Jan 1, 2001

By Kenneth P. Katen

Though the use of continuous mining machines consolidated the operations of cutting, drilling, blasting, and loading in one machine that would theoretically provide uninterrupted production, it was soon realized that the face haulage and roof support operations remained as major impediments to continuous production. The ability to provide not only continuous cutting and loading, but also continuous haulage and roof support (see Fig. I), was the basis for the introduction of mechanized longwall systems in this country from Europe in 1951. The early systems employed friction props for roof support, but were to become obsolete shortly after introduction of the first hydraulically powered, self-advancing supports in 1960. Since then, use of the longwall technique has grown to the point where it is currently providing more than 5% of the annual output of underground coal mines in the United States. The shortwall system had its origin in Australia, but was first introduced into this country in 1962 following the development of powered roof supports. It, too, provides for continuous cutting, loading, and roof support (see Fig. 2), but has not experienced the widespread popularity of longwall due to its inherent inability to easily provide for continuous haulage. While there are in the neighborhood of 100 longwall systems currently in operation in this country, there are only a handful of short- wall operations providing production of slightly more than 907 184.7 t/a (1,000,000 stpy) Both of these systems provide uninterrupted roof support for face operations by means of hydraulically powered steel roof supports. In each case, the coal removal consists of open-end cuts made from the narrow end of a large rectangular pillar (panel) which has been blocked out by continuous miners developing entries around its perimeter. However, this is the extent of the similarities between the two systems. It is hoped [ ] that the information presented in this chapter will enable the reader to better understand the two mechanical systems and the mining concepts involved in their employment.

Jan 1, 1981

By S. P. Taite, A. R. Charest, P. D. Lewis

The El Sauzal deposit is a classic, high sulfidation, epithermal gold system located in southwestern Chihuahua State, Mexico. The prospect was discovered by a Francisco Gold Corp. geologist in1995. El Sauzal was encountered as a result of an extensive grass-root exploration program in the rugged, dissected volcanic terrains of the Sierra Madre Occidental, around the historical Batopilas Silver Camp. At El Sauzal, high grade gold is hosted within a series of more permeable, low-dipping, lithic and fine-grained dacitic rocks of early Tertiary age. The mineralization appears to be both structurally and lithologically controlled. The alteration characteristics are typical of a high sulfidation system including kaolinite, illite, alunite, dickite and pyrophyllite. The deposit’s gold distribution, as recorded from drill-hole data and surface samples, varies from 0.2 to 650.0 g/t. The estimated geological resource, as calculated from an independent study completed in 1998, was 3.0 million oz @ 2.03 g/t including a minable reserve of1.8 million oz @ 3.3 g/t.

Jan 1, 2004

By B. Waquet

The genesis of a hydrothermal subsea mound, by chimney debris heaping and mineralizing fluid circulating upward, induces a vertical maturation gradient. Connected porosity is easy to measure and, after mineralogical evidence, can be use as a maturation index. Thus, to understand how a rock property evaluates with maturation, it is possible to plot it against connected porosity. Results are that uniaxial compressive strength, Young's modulus, and in a lesser certitude tensile strength, abrasivity and hardness, increase very weakly with maturation until a maturation threshold (equivalent to a connected porosity equal to 0.2), and rocket to much higher values after it.

Jan 1, 2011

By Z. Zhongwei

The leaching kinetic of mechanically activated sphalerite with acid FeCl3 solution was investigated. The result has shown that mechanical pre-treatment has greatly enhanced the leaching process. Comparing with the original concentrate, the activated one can be leached more completely at relatively lower temperature with diluter FeCl3 concentration within a shorter leaching time. The activation energy for the activated concentrate is 27 KJ/mol, while for the original one is 52 KJ/mol.

Jan 1, 1995

By Joseph P. Sobanski, Michael P. Bruen

The North Branch tunnel segment of the Tunnel and Reservoir Plan Mainstream System consists of 14,075 m (45,885 ft) of 9.2 m (30.2 ft) finished diameter and985 m (3,232 ft) of 2.5 m (8.25 ft) finished diameter concrete lined rock tunnels. The TBM mining and concrete lining methods used in completing this $166million project differed from “typical” TARP construction methods in that a two-stage concrete lining was placed and the lining was initially placed concurrently with TBM mining as a two pass system in the same tunnel segment. For the main tunnel (9.85 m diameter), TBM mining averaged 24 m/day (79 ft/day), excluding downtime associated with two main bearing changes, and the concrete lining placement, averaged 117 m/day (380 ft/day) and 53 m/day (174 ft/day) for the invert and arch segments, respectively.

Jan 1, 1999

By HASSAN E. EL-SHALL, AYMAN A. EL-MIDANY, KERRI-ANN A. HUE

Modifying the hydrophobicity of clay is necessary to accommodate large mycotoxin molecules such as zearalenone (ZEN). In this study, tricaprylmethylammonium (TCMA) chloride and common corn oil were used to modify clay. The results indicate that more than 90 percent of ZEN could be removed using clays modified by TCMA and corn oil at acidic and neutral pH due to the expansion of intergallery spacing as a result of TCMA surfactant intercalation within the clay-forming layers. The removal percentage depends on the pH and amount of clay used. Complete removal can be achieved at acidic pH and small clay amount.

By Mohammad Ranjbar, Zahra Manafi, FAZAELIPOOR MOHAMMAD HASSAN, HAMGHAVANDI MOHAMMAD RANJBAR, Mahin Schaffie

Bioleaching has an increasingly important place among available mining technologies as biological processes have emerged as alternatives for metal recovery, especially for metals like gold and copper. An important disadvantage of bioleaching is the slow reaction rates, with microbial attack times often lasting weeks. Therefore, applicable research is required to improve these rates. From previous research, copper bioleaching has been divided into two specific regimes: (1) surface reaction controlling step and (2) mix of surface reaction and diffusion controlling steps. The presented model, which includes the effects of both these regimes, predicted the results of copper bioleaching recovery with good accuracy.

By James C. Hower, B. K. Parekh

Introduction The purpose of coal preparation is to improve the quality of coal to make it suitable for a specific purpose by (1) cleaning to remove inorganic impurities; (2) sizing-crushing or screening, or both; and (3) special treatment, such as dedusting. The properties and quantities of impurities in coal are of major importance in the design and operation of steam generating equipment. Although boilers are often designed and equipped to use a wide range of coals, no boiler will perform equally well with all types of coals. All coals have certain properties that place limitations on their most advantageous use. These limitations are especially stringent for many of the older installations. Because of a general lowering of quality of raw coal in recent years, the need for coal cleaning has significantly increased. Among the factors contributing to the need for increased coal preparation are (1) increased demand for quality brought on by market and environmental requirements; (2) increased extraneous dilution caused by mine, health, and safety laws; and (3) depletion of the higher-quality coal seams. The major characteristics of coal and impurities from the standpoint of mechanical cleaning are particle size composition, generally called size consist; density differences; the relative friability of the coal and its associated impurities; hardness; and strength. Some of the other factors related to preparation are petrographic composition and rank. RANK CLASSIFICATION Coal is a general designation for a great number of solid organic minerals with different compositions and properties; all are rather rich in carbon and have a dark color, generally black. Next to mineral oil and kerogen, coal is the most important reservoir of carbon in the world. Carbon is an indispensable necessity of life as well as the main source of energy. Coals are found in stratified deposits, sometimes at great depths. All coals owe their origins to slow decomposition and chemical conversion of immense masses of organic material. As found in seams, coal is a heterogeneous mixture of organic and inorganic materials. Not only are there large differences in the properties of coal originating from different seams, but also in coal removed from different locations in a single seam. A genetic relationship exists between peats, brown coals, lignites, biturninous coals, and anthracites. As a whole, the process of coal formation, or coalification, proceeds as a continuous transformation of plant material, each phase characterized by a degree of coalification, or rank. As a measure of this rank, the carbon content or some related parameter can be used.

Jan 1, 1991

By Charles E. Weaver

A core from the La Camelia attapulgite mine in north Florida was studied in detail to determine the detailed vertical variability and the relations of the various parameters. The structural, textural, mineralogical and chemical data indicate there are two major depositional cycles represented within the minable interval. The sediments deposited during the two cycle differ in detail but in general are similar. The environments of deposition grade from shallow marine to lagoonal to tidal flat to marsh. The sedimentary structure (lamination, burrows, pebble conglomerate), mineralogy (attapulgite, montmorillonite, sepiolite, dolomite, calcite) chemistry (Al, Mg, Fe) are closely related to each other and their nature is determined by the depositional environments. Most of the clay minerals and carbonate minerals are authigenic and are therefore particularly sensitive to environmental differences. The variability and environmental features seen in this core are characteristic of the sediments in the general attapulgite mining area. A detailed understanding of the relationships discussed should be of value in prospecting, mining and processing.

Jan 1, 1972

By F. D. Wang

This paper presents an innovative mining method with the application of the water jet. The basic principle of this mining method is to mine a thin panel slice with a water jet system and to allow the roof to deflect elastically and subsequently to be supported by the coal floor without artificial roof support. Through the sequential mining of layers from top to bottom, the entire seam is extracted and the roof rests upon the mine floor. The advantages of this method are that the safety of underground operation can be greatly increased and the surface overburden disturbance will be markedly reduced. . An economic evaluation of such a system is presented for the total cost estimated per ton of coal mined at the face. This evaluation is then compared to that of a continuous mining section utilizing a room and pillar mining method.

Jan 1, 1991

By Harry W. Barr

Judging by the inquiries that come to Battelle, a number of companies have run into problems in determining the size and character of markets for mineral fillers in general and specialty fillers in particular. Usually these problems arise during a project to develop a new mineral filler when management suddenly realizes that a considerable sum of money will have to be spent before any profits are realized from sales of the new filler. What management needs in this case is the odds for or against the success of the development. And these odds frequently are controlled by the markets for the new filler. Basically, the problems involved in gaging markets can be simplified to how much of this new filler can be used and by whom? But there are some potential booby traps in these simple questions that should be exposed. This paper will discuss a few of these problems such as: 1. Describing the filler so that the prospective customer recognizes its possible applicability. 2. Finding; a prospective customer who can verify the filler's applicability. 3. Expanding successful test results to total industry markets. 4. Appraising competitive products, and 6. Discovering all the possible uses for the new filler.

Jan 1, 1961

By J. F. T. Agapito, L. J. Gilbride

High horizontal stresses were recognized to impact roof stability more than 60 years ago. Since then, numerous measurements associated high horizontal stresses with difficult ground conditions. This paper presents case histories illustrating the practical usage of roof stress determinations for helping assess stability, not only in the case of high horizontal stresses but also of low stresses. Examples are given of high stresses associated with faults, mine design changes, quantification of stress shadow effect, and anistrophy. The paper concludes with a comparative evaluation on the effect of various stress fields on ground support requirements.

Jan 1, 2002

By D. A. Elgillani

Oxidation potentials have been measured in the presence of various concentrations of cyanide, ferrocyanide, and ferricyanide and ethyl xanthate at various values of pH and related to flotation response. Eh-pH diagrams are constructed and show that the formation of surface ferric ferrocyanide is probably responsible for depression when cyanide is added. The influence of cyanide in the depression of pyrite with xanthates as collector has been the subject of many investigations (1,2,3,4,5,6), and from these studies several theories on the mechanism of depression have evolved. Wark and Cox (7) and Gaudin(8) have suggested that the depressing effect is due to a competition of cyanide ion with xanthate ion for the surface. Cook and his colleagues (9,10,11) have explained this phenomenon in terms of competition between hydrocyanic acid and xanthic acid. Sutherland (12) has shown that both of these theories describe accurately the relation between pH value and cyanide addition at constant collector addition but fail to describe the relationship, between pH value and the amount of collector required to cause flotation. Taggart(12) suggested that depression in these systems is due to the formation of a reaction product between ferric ion at the pyrite surface and ferrocyanide ion derived from solution. Majumdar(4,6) has attempted to prove this hypothesis by measuring the contact angles of pyrite in the presence of 25 mg/liter ethyl xanthate and different concentrations of potassium ferrocyanide and ferricyanide. In all cases the contact angles were quite high up to pH 10; these results indicate that pyrite should not be depressed by either potassium ferrocyanide or ferricyanide. In view of these facts, Majumdar has assumed that the compound Fe(CN)2 forms at the surface.

Jan 1, 1968