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By Poltak Sinaga

PT Kaltim Prima Coal's 13.1 km overland conveyor was commissioned in 1991. It is of conventional 3 roller 350 troughed belt type. Cost and performance optimisation during initial design ended up with 5.4m/s belt speed, 1,000mm belt width to convey 1,350tph, and 7mtpa of coal. Despite high initial figure, the belt speed was lifted to 6.5 mps in 1996 to accommodate mine throughput increase. In 2002, new low loss ST2100 1,100mm wide belt replaced the old ST2250 due for change-out. An upgrade project was initiated at the end of 2003 to further increase the belt speed to 8.5 mps, hence to increase the OLC capacity to 30mtpa. Performance data, experience of site personnel, site observation and tests, benchmarking, and information from equipment manufacturers were major inputs to the design review. The project fast track was another challenge in addition to executing modifications on a production lifeline. The project was completed within fifteen months and the OLC was successfully commissioned at 8.5 mps belt speed in February 2005. The OLC has been to date conveying 4200tph satisfactorily.

Jan 1, 2008

By Walter Keune

Object Modeling Technique. This formal descriptive language makes it possible to formulate requirements in the real world in such a way that they can be implemented in the form of entities (cf. Entity Relationship Model[Che83]) and methods (see Figure 1). The object {Roadway} is graphically depicted by means of the Polygon method.

Jan 1, 1996

By T. P. Weldum

INTRODUCTION Cleveland-Cliffs' operations in Michigan have been utilizing fully autogenous grinding for over four decades. This is but one of the key characteristics of the iron ore processing method that was developed for the extremely fine grained, low grade deposits of the region. Liberation size of the hematite and magnetite ranges from about 30 to less than 1 micron. Typical grinding fineness target to achieve silica grade in the concentrate is 80 to 90% passing 25 microns, or a P80 of approximately 20 microns. After primary grinding, the magnetite ore is first upgraded by rougher magnetic separation. It is then ground to final product size, sent through thickener-sizers utilizing selective flocculation, upgraded again by finisher magnetic separation, and then brought to final silica grade by reverse amine flotation. Hematite ore follows essentially the same route, less the magnetic separation stages. Concentrate is filtered and pelletized, along with con- trolled additions of fluxstone, to ready it for shipping. Iron ore pellets on the water of the Great Lakes have a value of approximately 1.5 cents per pound. GRINDING PROCESS DESCRIPTION Details of the Empire magnetite grinding process flowsheet have been presented by Greenwood and Rajala (1992), and more recently by Rose et al. (2002). The Tilden comminution process for either magnetite or hematite is essentially identical, with the exception of some variations in the excess pebble treatment methods (McIvor and

Jan 1, 2004

By G. R. Rao, K. A. Natarajan, P. Devasia

The role of growth conditions and adhesion of Thiobacillus ferrooxidans on the leaching of chalcopyrite was investigated. Thiobacillus ferrooxidans grown on sulfur, thiosulfate and ferrous ion substrates was used in this comparative study. Growth on sulfur, a solid substrate, requires bacterial adhesion unlike that required in the presence of soluble thiosulfate and ferrous ion in a mineral-salts medium. Solid substrate-grown cells showed higher rates of leaching than those grown in liquid media. An initial lag period noticed during leaching by solution-grown cells was absent when solid substrate-grown cells were used. Such a behavior is attributed to the presence of an inducible proteinaceous cell-surface appendage on the sulfur-grown cells. This appendage aids in bacterial adhesion onto the mineral surfaces. Such an appendage is absent in solution-grown cells, as substantiated by electrophoretic measurements. The importance of bacterial adhesion and the direct mechanism in leaching by Thiobacillus ferrooxidans are demonstrated.

Jan 1, 1997

By Ahmet Unal

Inexpensive and effective means of delivering courses to mining engineers who live at remote and scattered locations remains to be a challenging issue. Computer-based instructorless but interactive multimedia delivery is a good substitute to traditional short courses and one-way broadcasts. Such a system, enhanced with a wide area network, is an inexpensive alternative to two-way broadcasts and even to a traditional university. Course material can either be delivered on compact disks (CDs) or on-line from the host servers over the phone lines using a personal computer and a modem. Although technically not feasible using ordinary telephone service lines at the present time without further modification, advances in this field indicate that this up and coming medium may dominate the competition in the future. This paper investigates the present and the future of this technology and discusses the experiences gained in creating and disseminating a prototype multimedia CD which was created at the Rock Mechanics and Explosives Research Institute of the University of Missouri-Rolla to teach a portion of a course in Ground Control. The hardware and software used in creating the audio, 3-0 graphics, animation dips, video clips, and movies are listed. The structure of the program and the way how interactivity was achieved is explained in detail.

Jan 1, 1996

At the dawn of the computer age in the early 1950's, few people in either the minerals industry or the field of electronic data processing (EDP) would have predicted the tremendous impact that the computer has had on the way we conduct our everyday lives and businesses. Herman Hollerith himself (see next page), the Columbia University mining engineer 'turned statistician who developed the first punched card electronic tabulating machines for the US Census Office in the late 1880's, would doubt- less be amazed at the progress that has been made in the application of data processing techniques to nearly all aspects of the mining cycle (Aul, 1974). More than any other factor, the availability of economical computing equipment has led the way for the development of the broad range of mining computer methods described in this text. While limits have been identified for many of the technologies commonly in use today, new technological advancements point to continued exponential advancements in computing price-performance in the 1980's. With those advancements, we may look forward to continued expansion of the role computers will play in mineral production.

Jan 1, 1979

By Raymond J. P. Brouzes

INTRODUCTION [A Decade After the 1972 Stockholm Conference] The UN-sponsored Stockholm Environmental Conference held just over 10 years ago was the first successful attempt to achieve global recognition of environmental issues. Indicative of the lack of concrete involvement in environmental protection to that time was the fact that only 15 nations had a department or ministry responsible for environmental affairs compared to today's 143. Many governments were uncertain of what were the most serious or pressing problems in their country. There was obviously a need to both identify those issues and to determine how to manage them once identified. At the same time, the public at large was becoming more critically aware that environmental protection had been neglected by government and often ignored by industry. It soon became evident that large amounts of money would have to be spent to redress some of the more evident problems. However, many developing nations were reluctant to slow down the much-needed industrial growth by imposing costly environmental controls on industry. In fact, some waived environmental control altogether as an incentive to attract industry. In some sectors, it was often stated that industrial development and environmental protection were mutually exclusive activities. The need of an awareness, commitment and dedication by all sectors of society to protect their environment was just beginning to develop, replacing the rather simplistic view that all environmental problems were caused by greedy industry.

Jan 1, 1984

By Richard Komarek

When limestone (Ca03) is calcined in rotary kilns to produce quicklime (CaO), it is not unusual for 10% to 20% of the stone to abrade and emerge from the kiln as quicklime fines (-6.3 mm or -0.25 in.). While there are various industrial processes that can use fines, handling and shipping is tricky and dangerous. Due to the highly caustic nature of quicklime, airborne dust easily bums eyes and skin. On the other hand, money has already been invested in mining (or buying) the raw material and in the equipment and energy needed for calcining. Discarding the fines will not only waste that investment, but add even more cost in transportation and possibly dumping charges. So the question becomes, how can fines best be turned into a revenue-generating asset? Some plants convert leftover quick-lime fines into calcium hydroxide - Ca(OH)2, also known as hydrated or water-slaked lime - for sale into agricultural applications. For farm uses, hydrated lime fines are preferred over quicklime because they are easier to handle. And they are favored over raw limestone fines for their higher concentration of calcium and greater solubil¬ity. From the producer's viewpoint, quicklime fines are ideal for this use because they go through hydration faster than the larger chunks of quicklime. Those larger chunks, or "pebble lime," are more readily salable and more easily handled, for such uses as steel, copper, aluminum and magnesium production, water waste treatment, chemical, paper, glassmaking and flue gas desulfurization in coal- fired boilers.

Jan 1, 1993

By Edward Donovan, Bryan Knott, R. E. Melley, O&apos

South Bulga Colliery, located near Singleton in the Hunter Valley region of Australia, began longwall production in late 1994. The mining conditions there are conducive to high productivity with good roof conditions and a shallow seam with production areas located close to the portal. When the longwall was commissioned, the low capacity and availability of the conveyor system greatly curtailed the mine's productivity. A number of changes were made to the conveyor system culminating in a drive change out to improve the system. Using South Bulga as a case study, this paper aims to demonstrate the absolute necessity of a reliable, high performance conveyor system for the viability of a mine, and some of the factors that are needed to ensure a conveyor system performs as intended. These factors include a thorough understanding of the individual components and how they influence and interact with each other; a system design that is tolerant of variations in component performance and the necessity of robust and reliable communications and PLC programming.

Jan 1, 1996

By Mark L. Bricker

The Jim Bridger Coal Mine, operated by Bridger Coal Co., is located in Sweetwater County, WY about 56 km (35 miles) northeast of Rock Springs. Bridger Coal is a joint ven¬ture between Nerco Coal Corp, the operator, and Idaho Energy Resources Co. The permit boundary encompasses more than 81 km'- (20,000 acres) on the western side of the Continental Divide. Since the mine began opera¬tions in 1974, it has produced about 82 Mt (90 million st) of coal while moving about 344 hm3 (450 million cu yd) of virgin earth. Annual production averages 4.5 Mt to 6.4 Mt (5 million to 7 million st) of run-of-mine coal. Coal is consumed on-site by the Jim Bridger Power Plant, a 2000-MW generating station. Electricity is transmitted to the Pacific Northwest power grid that includes Oregon, Idaho and northern California. Geology The mine is located on the northeast flank of the Rock Springs uplift. This is a broad, asymmetrical anticlinal feature about 97 km (60 miles) long and 56 km (35 miles) wide with a north-trending axis. This uplift separates the Green River Basin to the west and the Great Divide and Washakie Basins to the east. Precambrian rocks on the apex of the uplift are estimated to be 5200 m (17,000 ft) above the Precambrian rocks in the Green River and Washakie Basins. Normal faults with generally less than 30-m (100-ft) vertical displacement cut through the uplift. The dip of strata on the flanks is generally between 3° and 15°.

Jan 1, 1991

By Michel Dagbert

The determination of the precision of reserve estimates (tonnage, grade, quantity of metal) for an entire deposit or a large block in a deposit has received some attention in the early developments of geostatistics. A general formula to derive the estimation variance of any linear combination of a large number of sample values can be found in any geostatistical textbook like David (1977) or Journel and Huijbregts (1978). A particular case of this general formula is of course the kriging of the entire deposit. However, besides the technical difficulty of dealing with many samples the application of this formula necessitates the knowledge of the covariance between any two samples in the deposit. This is quite unrealistic in the usual case of limited stationarity where the assumption of a covariance or a variogram just function of the distance vector between two samples is only valid for samples within the same area of restricted size.

Jan 1, 1982

By William H. Schiffbauer

Research is being conducted toward making underground mining equipment autonomous. This will facilitate improvements in safety by relieving workers of dangerous tasks and will increase production by providing more accurate control with less down time.. A Bureau of Mines developed microcomputer network has enhanced this research by permitting a group of diverse computers to interact with a mining machine as well as with each other over a common data link. The network is composed of specially integrated off-the-shelf hardware and industry-standard operating system and programming languages. Using the network, researchers can conduct various experiments with the mining machine using a diverse group of intelligent sensors, computers, and microcontrollers. Descriptions of the mining machine, the mining machine control computer, control algorithms, -the microcomputer network architecture, and communication protocols are discussed.

Jan 1, 1989

By Randal J. Barnes

Computer based techniques for solving the Ultimate Pit Limit Problem have appeared in mining literature since the early 1960's. The majority of papers pertaining to this subject can be partitioned into one of two categories: discussion of the pros and cons of a particular algorithm, or a case study presenting specific applications of an algorithm. Subsequently, there has a1 so been considerable debate concerning the best techniques between, essentially, two camps: those favoring the moving cones techniques, and those favoring the techniques which yield true optimal pit designs. The purpose of this paper is not to add to this debate, but rather to present a few new ideas (partially a new look at an old idea), which can be easily implemented to noticeably improve any ultimate pit limit approach independent of the particular algorithm used. These ideas fall under the heading of "bounding the optimum" (Barnes and Johnson, 1980).

Jan 1, 1982

By Fathi Habashi

LEACHING IS the process of extracting a soluble constituent from a solid by means of a solvent. In extractive metallurgy it is the process of dissolving a certain mineral (or minerals) from an ore or a concentrate, or dissolving certain constituents from metallurgical products such as calcines, mattes, scrap alloys, anodic slimes, etc. In this respect, either one of two purposes can be achieved: 1) Opening of ores, concentrates, or metallurgical products to recover the metal values. 2) Leaching easily soluble constituents (usually gangue minerals) in an ore or a concentrate in order to have it in a more concentrated form, e.g., the

Jan 1, 1970

By J. N. Carras, N. W. Bainbridge

In order to further the understanding of spontaneous heating of longwall goafs a numerical model was developed, based on conservation principles applied to the transport of heat, water vapour and oxygen across the god Advective air flow into the goaf is caused by the differential air pressures across the god The air velocity field within the goaf area was computed using Darcy's law. The boundary and initial conditions concern air pressure, temperature and relative humidity. The oxidation rates and heat generation rates of the goaf materials required for the simulation were obtained from laboratory measurements. The main outputs of the model are temperature, oxygen and water contour maps, the rate of air leakage into the go4 velocity field and pressure distribution across the god. The model while still in its development stage, is able to simulate a heterogenous goafs constructed from different materials with different thermal and mass flow properties. Validation of the model by comparing its output with measurements from within goafs is required before the model can be used with confidence in a predictive sense.

Jan 1, 1995

By Rodger E. Denison

The Middle Ordovician Simpson Group in the Arbuckle Mountains of southern Oklahoma contains sandstones of unusual purity. These have been exploited as glass sands since 1913 (Ham, 1945). Where quarried, the sandstones are uncemented or weakly cemented, greatly facilitating mining and processing. The origin: sedimentary setting, and lack of cementation of these valuable sands has been the source of much discussion. The lowest of the sandstone units in the Simpson is at the base of the Oil Creek Formation. The basal Oil Creek sandstone is exposed in a series of accessible quarries north of the town of Mill Creek in Johnston County. Virtually all conclusions and generalizations concerning origin of the Simpson sandstones are based upon observations made in these quarries. The three Simpson sandstones overlying the Oil Creek share many of the same distinctive qualities, and there is an assumption that they share a common origin.

Jan 1, 1999

By Harry R. Price, Keith M. Swaffar

The Northeast Raw Water Tunnel transports untreated water to the Detroit Water and Sewerage Department's (DWSD) Northeast Water Plant where it is treated and distributed. The occurrence of a subsidence area which was attributed to the tunnel prompted the DWSD to have the tunnel investigated. After an extensive historical and geotechnical investigation, two access shafts were constructed along the alignment in the vicinity of the subsidence. Following completion of the shafts, the subsidence area was inspected in the wet prior to dewatering the tunnel. Upon the completion of dewatering, a dry inspection was performed. During the dry inspection, an area of significant distress was encountered where sand and silt were boiling into the tunnel along with large volumes of groundwater. This distressed area was located 800m (1/2 mile) north of the original subsidence area. The tunnel was immediately refilled with water and an emergency repair program was planned and implemented. As a result of the distressed nature of the secondary tunnel liner, dewatering of the tunnel could not be performed until the secondary liner and the surrounding soils were stabilized. This paper presents a case history of both the investigation and the repairs of the Northeast Raw Water Tunnel including the various grouting and unique tunnel stabilization methodologies which were utilized.

Jan 1, 1987

By Derek M. Hutchinson, Don Zeni

The construction of shafts by blind drilling has been made cost effective by advances in technology and experience. The techniques of blind shaft drilling are discussed and a brief history presented. A recent use of blind shaft drilling to access a small gold ore body in Australia is described. Finally, the most recent developments in drilling machinery are reviewed together with possible applications in new and existing mines.

Jan 1, 1987

By James M. Murphy

INTRODUCTION In the fall of 1983, the fourth new Rapid Transit System constructed in this country in the last forty years will go into revenue service. The Baltimore Metro will bring to this major Mid-Atlantic seaport the first phase of a planned intermodal transit system, serving a metropolitan area with a population in excess of four million people. Originally, the Mass Transit Administration (MTA) considered construction of a twenty-eight mile system known as Phase 1. Its two lines would run from the center of Baltimore City, one going northwest to Owings Mills and the other south to Anne Arundel County. Legislative approval was granted in April, 1976; however, funding was limited to constructing a segment fewer than eight miles in length, along the northwest corridor from Charles Center to the Baltimore City county line. This segment is known as Section A. The project is 80% federally funded and 20% state funded, with a capital cost estimate of $797,000,000 to complete. This report addresses the development and implementation of a Coordinated Insurance Program for the construction phase of Section A, and includes a description of the associated risk management process. GENERAL DESCRIPTION OF SECTION A Section A of the Baltimore Metro is composed of a rapid transit line eight miles in length which serves the northwest corridor between Charles Center in downtown Baltimore and Reisterstown Plaza at the Baltimore City county boundary. The line is completely grade separated and, once operational, will provide high speed automated rapid

Jan 1, 1983

By D. R. Nagaraj

Literally thousands of new flotation agents, both collectors and modifiers, have been proposed for sulfide and non-sulfide flotation over the past six decades since the beginning of the use of soluble surfactants in flotation. In stark contrast, the number of flotation agents used in practice is small. Xanthates and fatly acids, along with a few well-recognized modifiers, dominate the industry. Three major questions will then arise: a) are there truly specific needs in the industry that call for chemistries that are different from those used currently ? b) if yes, given the track record in the industry, what is the likelihood that such different chemistries will ever be used and to what extent ? and c) is more research into developing new chemistries necessary ? A critical assessment of flotation agents in general is made in this paper to provide answers to these questions and to identify the major factors that are responsible for the large disparity that exists between flotation reagent research and commercial usage.

Jan 1, 1994