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By T. Orgodol, P. Korpi

This paper describes the Boroo Gold Company (BGC) ore processing plant which is the first CIL/CIP plant in Mongolia. BGC is the first foreign investment in Mongolia since 1990 and follows the highest safety and environmental standards. Commissioning of the plant commenced in October 2003 and commercial production began in March 2004. Gold recovery is by gravity and conventional leaching and carbon adsorption. Detoxification of the leach tails is by the SO2/Air method before discharging the tails to the tailings pond. Ore types treated at Boroo are predominantly oxide with some transition ore as mining reaches the lower sulphide zone. There are several interesting technological issues and projects ongoing at Boroo which will also be discussed.

Jan 1, 2007

By Janet E. Lamarre

Current statistics show that 90% of new-business failures are caused by the unsuitability of the entrepreneur for the business he has started. Are you a suitable candidate for success as a consulting geologist? Should you start your own geologic consulting business, and when? This paper investigates the demand for consultants with respect to general economic trends and mineral exploration activity trends. Furthermore, the study reveals certain technical skills and personal characteristics important to the success of the consulting geologist. Research shows chat certain expectations which prompted geologists to change careers are fulfilled while other unanticipated expectations often are also met.

Jan 1, 1985

By L. G. Stolarczyk, R. C. Fry

In coal-bearing formations, seams are often bounded by sedimentary layers of mudstone, claystone or shale. When the electrical conductivity of the surrounding sediment layers is greater than the conductivity of the seam, a natural parallel plate waveguide forms in the strata. For frequencies below the AM broadcast band, the waveguide can be used for the transmission of electromagnetic (EM) waves. In a uniform seam, the primary wave travels in the coal layer along paths between a radiating antenna and a distant receiving antenna. The travel distance increases with seam height and the conductivity of the surrounding sediment layers. The distance decreases with increased coal conductivity. In Cretaceous western bituminous coal, the distance may exceed 549 m (1800 ft). Anomalous geologic disturbance zones such as faults, shear zones, paleochannels, sills and dikes significantly alter the values of EM wave propagation constants (attenuation and phase) expected in a uniform seam. In the neighborhood of an anomaly, EM wave energy is scattered (reflected and diffracted). Scattering creates secondary waves in the seam wave guide. A receiving antenna at a remote location in the coal seam can be used to measure the magnitude and phase of the EM wave at the end of the path. The measured data can be processed to determine the average value of the propagation constants along each path. Paths with anomalous propagation constants are used to locate and image geologic disturbance zones. Radio Imaging Method (RIM) instrumentation, survey procedures and data processing (tomography) algorithms have been developed to image geologic structure in advance of mining. The survey is conducted between gate roads of a longwall panel. Data processing constructs contours of constant attenuation rate (phase constant) across the plan view of the panel. In anomalous zones, the contours rapidly change with distance. The shape of the contour lines generates a visual image of the anomaly and suggests the type of anomalous condition to be expected in the coal seam. This paper briefly discusses the depositional environment and the formation of the imperfect waveguide in coal-bearing strata. The linkage between sedimentary geology and EM wave theory establishes an understanding of how the propagation constants depend on the anomalous geologic conditions. A case study compares in-mine geologic mapping with the tomographic image of a longwall panel.

Jan 1, 1991

By R. L. Grayson, S. Yuan

A stochastic model for evaluating the impact of the reliability and maintainability of shovels and trucks on the operational effectiveness of shovel-truck mining systems is presented. In the model, the Markov modeling technique is used to analyze the operating status of a shovel-truck mining system. Then, simulation is used to study the productivity of a shovel-truck system in a particular state. Finally, the relationship between the effectiveness of a shovel-truck system in terms of productivity and the reliability and maintainability of equipment is established. This relationship may be very useful to mine managers in making decisions in surface mining (e.g., regarding production process control, equipment replacement, and maintenance planning). A quantitative study is given to demonstrate how the reliability and maintainability of equipment affect the system effectiveness and how to pinpoint the parameter that has the most significant effect on the system effectiveness. The quantitative study indicated that in order to improve the system effectiveness significantly, the reliability and maintainability of the equipment need to be improved simultaneously.

Jan 1, 1995

By Charles H. Arnold, Timothy Fallara, David A. Day, Paul H. Marshall

The Upper Scioto West Interceptor Sewer (USWIS), Parts 1 and 2, consists of approximately 7,128 meters (23,385 ft) of 328 cm (129 in.) diameter tunnel. The project ex-tends from the City of Dublin to Griggs Dam in the City of Columbus. The majority of the tunnel was designed for excavation in rock by TBM. The remaining portions span pre-glaciation formed valleys in-filled with glacially-derived sediments. Tunnel construction in one of the glacial till filled sections includes excavation by drilling and controlled blasting. The other section will be constructed by ground consolidation followed by excavation by TBM. This paper describes the methods employed to mine the glacial till filled valleys.

Jan 1, 1997

By C. William Parisi

Since the introduction of mechanical mining, some 35 years ago, a great deal of effort has been expended by the coal industry to solve the coal dust problem. The original concern was the possibility of a dust explosion or the propagation of a gas ignition; however, in recent years it has come to be recognized as a possible 'health hazard as well. In the middle thirties, the Pittsburgh Coal Company began an intensive study of the dust problem to determine the dust levels created by the various cycles of operation in mechanical mining and to make a comparison with those of hand loading operations. Numerous dust samples were collected with a midget impinger and it was found that dust counts varied from 38 to 268 million particles per cubic foot during hand loading and from 96 to 227 million particles per cubic foot during mechanical loading. The study indicated that the source of underground dust in coal mining could be classified as primary or secondary. A primary source is one associated with appreciable degradation of size, that is, where most of the fines capable of becoming air-borne are produced. A secondary source is one in which most of the fines have been produced at some previous operation and are in such condition that they can become air-borne. Cutting, drilling and blasting are the operations which produce the primary dust. Secondary dust is formed by operations which include; loading, transportation and discharge at transfer points. The study showed clearly that the coal cutting operation was responsible for the greatest amount of dust and that the amount of dust produced varied directly with the speed of cutting; type and dullness of cutting bits; and the distance the cuttings had to fall to the floor. The information obtained from the study enabled our company to decide on a course of action and the direction to follow. With the cooperation of mining machine manufacturers, water tanks with a 200 gallon capacity were built into the machine trucks and were provided with a pump driven by a small motor. A length of 1/2" water hose carried the water from the pump to the two water spray nozzles located at the front of the machine. Water was delivered to the machine tanks by water cars which were filled on the surface or from an underground water supply. It was during these early days that wetting agents were introduced into the water system. Our studies revealed that wetting agents did little better than plain water in the abatement of the dust problem. It was found that when using a wetting agent less water was required to obtain the same results but we could not take advantage of this fact because it was almost impossible to keep the smaller nozzles open to reduce the amount of water being used.

Jan 1, 1967

By Y. Zimmels, C. Feldman

Closed-circuit grinding processes are considered in the context of a reactor-separator circuit that involves multifraction streams and products. Because grinding circuits are low-efficiency, capital-intensive operations, modeling to maximize their economic return is appropriate. An attempt to develop and test such a model is presented in this work. The model relies on process simulation for both the mill and the separator, in conjunction with constraints imposed by product specifications. The grinding process was simulated using breakage functions, which provided complete data on the feed and product of the mill. A cyclone bank used as the separator was also simulated using known models. The overall process model provided a complete simulation of the multistream grinding and separation process. The process model was then incorporated into an economic model that predicts grinding cost, subject to process constraints, for a given set of operating variables. The model facilitates economic optimization of the grinding process as it relates to process variables and process hardware.

Jan 1, 1993

By R. L. Jones, D. D. Runnels, D. P. Dupon, D. J. Cline

To establish meaningful remediation goals and monitoring programs in areas disturbed by mining and associated industries, it is desirable to determine the natural concentrations of metals that existed in these areas prior to being disturbed. In mineralized areas, multiple natural populations of metals and associated components may be present. This paper describes a method for characterizing the natural background chemistry by means of probability distribution dia¬grams. The method can be applied to water, soil and other natural materials. In a study of a complicated hydrogeologic system at the Kennecott Utah Copper North and South Operational Areas near Salt Lake City, UT, probability distribution diagrams were used to differentiate between natural background waters and waters impacted by human activities. The probability distribution diagrams allowed a component-by-¬component interpretation of the chemistry of ground¬water and surface water over a large geographic area. Natural chemical background populations and anthro¬pogenic effects were identified Although the method is illustrated for mining-related sites, the same approach can also be used for other natural and anthropogeni¬cally impacted sites.

Jan 1, 1999

By M. F. Corcoran

Rapid advances have been made in the past few years in the application of automatic controls and instrumentation to iron ore pelletizing plants. Present practice in applying instrumentation and control to the Grate-Kiln system of iron ore pelletizing is described. Major control points and loops are tabulated. Future trends in the application of digital control including computer data logging systems are described.

Jan 1, 1965

By Uday Kumar

This paper presents details of an availability study for a fleet of diesel engine operated load-haul-dump (LHD) machines used in a Swedish mine. For the purpose of this study, the LHD machines have been considered as a system comprised of many subsystems like engine, brake, transmission, etc., in series. As availability is dependent on both the reliability and maintainability characteristics of the system, together with reliability, the concepts of maintainability are also discussed. The need for exploring the data for the presence of any structure, which is very common in repairable system data sets, is emphasized with suitable examples. Simple graphical techniques are used for verifying the independent and identically distributed (IID) assumption for the data set. The error introduced due to the use of the exponential distribution in place of more appropriate distributions in estimation of availability and reliability characteristics is analysed.

Jan 1, 1989

By S. Chander

Neutralization of acidity by addition of alkaline materials is a commonly used method to treat acid mine drainage. However, this procedure requires large amounts of reagents based on acid-base accounting. The potential use of organic additives in preventing or ameliorating acid mine drainage was investigated in this research. The tests were conducted in weathering columns using refuse samples from a coal cleaning plant. Both cationic and anionic compounds were tested. For a comparison, tests were made in the presence of limestone and lime. The results show that some of the reagents substantially retarded the rate of oxidation whereas others even enhanced it. The suppression of the rate of pyrite oxidation was ascribed to surface chelation. Formation of surface compounds prevented the pyrite particles from further oxidation. Such a treatment required only small quantities of reagents since the reaction was confined to the surface.

Jan 1, 1992

By Joseph Kurtak

When prospectors discovered mineralized outcrops in Pine Creek Canyon in 1916, little did they know the site was destined to become one of the world's greatest tungsten mines. Located outside Bishop in California's rugged Sierra Nevada mountain range, the mine's development imposed unique challenges to the hardiest of mining men. In its early years, the Pine Creek operation was plagued by bad luck and poor timing. But through the perseverance of a dynamic group of mining personalities, it would gain world class status. Pine Creek tungsten supplied much of the defense needs of the United States during World War II and put the Bishop area on the map as a major contributor to the nation's stockpile of strategic metals. The mine's history was shaped by world politics, the ups and downs of metals demand and economic survival through technological innovations. In contrast to many mines, Pine Creek's workings went horizontally into and then up inside the mountains - nearly to the ridgetops. This resulted in the name "Mine in the Sky" being attached to the operation. The origin of Pine Creek's ore bodies is related to the emplacement of a portion of the Sierra Nevada batholith about 100 million years ago. During the intrusive process, granitic magmas engulfed overlying calcareous sedimentary rocks, flooding them with silica-rich hydrothermal fluids and metamorphosing them to skarn. The fluids also contained tungsten, molybdenum and copper. They precipitated as scheelite, molybdenite and chalcopyrite, respectively, during the metamorphic process. The ore-bearing skarns occur as near-vertical tabular pendants in the intrusive rocks. These were later exposed by the uplift of the Sierra Nevada mountain range and glacial erosion.

Jan 1, 1998

By E. G. Kelly

Many methods of evaluating the efficiency of mineral separations have been described in the literature. In most cases, these present the efficiency as a single number. This paper argues that single-number measures of efficiency are inadequate because they seldom allow reliable comparisons, and are unlikely to correspond to the optimum operating conditions. To realistically make comparisons, it is necessary to distinguish the particle-induced component from the equipment- induced component. In a number of situations where the separating property can be identified (such as in gravity concentration and classification), this can often be done. However, in more complicated systems, such as flotation, this has not been possible. A technique is described whereby particle and equipment contributions to efficiency can be distinguished without the need to define the separation property. Because smelter schedules define a boundary correlation between grade and recovery, they generate some of the better single¬-number measures of efficiency, but even these have limitations.

Jan 1, 1991

By J. G. Russell

The valuation of known mineral re-serves entails the economic evaluation of the mining enterprise and the valuation of other assets employed, including mining and processing plant and intangible assets. A case study approach analyzes two reserve situations: ownership of reserves (phosphate rock), and leasing of reserve lands (kaolin). The appraisal of the physical property is outlined, along with the economic analysis of the operation. The discounted net cash flow approach is used to value the enterprise, leading to value of the reserves after correlation with other assets employed.

Jan 1, 1989

By A. S. Malicsi, M. D. Baker, I. Iwasaki

Fine grinding may he required for- some coals to remove sulfur and ash or to prepare coal-water slurry. Fine grinding leads to increased hall wear and its effect on the surface properties of the ground coal becomes of concern. Marked hall wear - tests were performed to study the effects of oxygen, pH, the soluble species of coal, and the addition of pyrrhotite on hall wear. The synergistic action of coal and oxygen greatly enhanced the corrosion of mild steel halls during grinding. Elec.trochemica1 measurements on a mild steel electrode in coal slurries and SEM observations of grinding hall surfaces were carried out to explore the corrosive wear mechanism.

Jan 1, 1991

By K. A. Prisbrey

Mineral carbonation is the reaction of carbon dioxide with mineral silicates to form solid, carbonate compounds. The carbonate ion holds carbon in a low energy state – lower than in carbon dioxide. Thus the reaction of carbon dioxide to produce mineral carbonates captures the carbon in a stable, solid form. The University of Utah is investigating the carbonation of silicate minerals by mechanochemical processing, which has the potential of being much less expensive than other methods. Tests to date have shown that a marked change takes place in the lizardite variety of serpentine after 15 to 20 minutes of intense grinding in the presence of gaseous CO2. Further testing is in progress.

Jan 1, 2004

By Yun Bai, Ang Chen, Xiangdong Hu, Yanfei Zhu, Gang Li

"It is well known that tunnelling involves a high degree of risk. Conventional risk management only evaluates risks and chooses mitigation measures before the start of a project. However, mitigation measures also introduce risks, which are ignored in the conventional risk control process when choosing different measures. The Multiphase Risk Management Method (MRMM) takes the risk of mitigation measures and dynamic risk control into consideration. This paper introduces this new method and provides a flow chart for better understanding. A case study of the MRMM is given based on Ningbo Metro Line 3, the first quasi rectangle shield tunnel in China. INTRODUCTION Tunnelling itself is generally complex and involves a high degree of uncertainty (Huang, 2006; Thompson and Thompson, 2006). In recent years, several metro tunnel projects in China have been involved in accidents (Wang, 2006; Gong and Zhang, 2012).As a result, Chinese tunnel engineers are paying more and more attention to risk management in tunnel projects (Xiao-lin and Ping et al., 2009; Zhong and Jia et al., 2014), and scholars around the world have put forward many management processes. Existing risk management mainly focuses on a particular stage of a tunneling project. Tunnel engineers or other project parties usually carry out risk assessment and set up schemes or choose mitigation measures before a project begins. The risk from this initial risk assessment may be defined as the initial risk (Bai and Dai et al., 2013). This kind of managing process has been widely used for its simplicity and comprehensibility. However, this static theory cannot properly reveal the dynamic character of the risk during tunnelling. In addition, to reduce the risk from unacceptable level to acceptable level also calls for optimum measures. Therefore, the multiphase risk management method was proposed (Bai and Dai et al., 2013). The purpose of this paper is to introduce and develop the MRMM, and to provide a brief flow chart to illustrate the risk management process based on it. Finally, an example of the first quasi rectangle shield tunnel in China in Ningbo Metro Line 3 is illustrated. It analyzes the initial and secondary risk and sets up a risk control system."

Jan 1, 2016

By K. Hiroto, H. Tamamoto, G. J. Kusuma

"Acid mine drainage (AMD) has become a serious environmental problem in the mining industry in the last decade. Many efforts have been made in an attempt to find a better method to manage this problem in a proper manner, both through prevention and mitigation. One of the methods to prevent AMD generation is a dry dump cover system that has been proposed to minimize oxidation of sulphide waste rock in dumping sites. The performance of this system depends on the physical and geochemical stability of a barrier layer to minimize water and oxygen influx. In the mining industry, this barrier layer is formed by using Inert/Non Acid Forming (NAF) waste rocks to cover Potentially Acid Forming (PAF) underneath. However, the availability of NAF waste rocks, due to the geological condition, mining sequence and capability of equipment, is limited in some mines. This paper will discuss the acid generation mechanism, application of a cover system and its problem being faced in an Indonesian coal mine, and describe a preliminary laboratory result of a multi layer cover system in an attempt to overcome this problem."

Jan 1, 2011

By B. Ceccarelli

Many public domain programs useful in mining engineering, e.g., MULSIM, DZTAB, and EXPAREA, require tedious data input and generate pages and pages of printed output. To eliminate the tedium and to enhance the output, ETI U.S., Inc. developed GEM, Graphics for Engineering and Mining, a collection of application programs and underlying interface tools for VAX/VMS computers. This paper presents an example of how an application program in GEM enhances a specific public domain program. It describes how GEM provides automated graphics assisted input and output. The paper describes how this program uses the GEM User Interface: the 3D GKS device independent graphics, server and drivers, various mining, mathematical and statistical algorithms, the means of handling graphics, data including IGES, and the foreign language interface.

Jan 1, 1992

By H. G. Linge

Pyrrhotite (FeS1+x ,0<x<0.15) is an iron sulfide which is considered to be a pest in carbon-in-pulp/ leach (CIP/L) gold processing [l].The perceived influence of pyrrhotite on gold processing by CIP/L is a competing consumption of 02 and CN­as the pyrrhotite dissolves by oxidation [1,2]. The few studies of the oxidation chemistry, kinetics and mechanism of the oxidation ofpyrrhotite are reviewed in detail elsewhere [3].There is broad agreement that the surface of pyrrhotite is very rapidly oxidized to form a thin (e.g. 10 nm) ferric hydroxy-oxide layer which overlays an iron-deficient sulfide lattice covering the original pyrrhotite. The reaction can be summarized thus:

Jan 1, 1995