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By G. F. Revey

All underground operations have limiting factors that influence overall profitability. Hoisting, hauling, available headings, labor, milling capacity and other factors limit how much material can be removed from an underground mine. Consequently, when mines use limited labor to handle the additional rock from overbreak and to perform extra ground support tasks, productive activity is replaced by non-productive work. Mining economics are further penalized when overbreak causes dilution of ore grades. This paper reviews organizational systems that mines have used to create environments which foster the creation of successful overbreak control programs. Actual case histories document the various quality improvement techniques, worker incentives, and practical project management systems used by these mines. A brief review of controlled blasting technology sources and overbreak measurement tools is also included.

Jan 1, 1997

By Donald H. Dowlin

The design of a preparation plant for minimum maintenance and clean up requires both the skills of the Engineer and the practical experience of the Operator. From the initial flow sheet and preliminary design until the plant is completed and operating, each phase of the work must be thoroughly explored for simplicity, workability and high efficiency. It is the responsibility of the Designing Engineer to develop the plant around the basic flow sheet, selecting equipment and materials not only with regards to Initial cost but also required upkeep and repair.

Jan 1, 1962

By G. W. Phelps

This discussion deals with the geology o£ the Tennessee-Kentucky ball clay deposits; their mineralogy and chemistry; methods of finding, mining and refining; and makes observations on reserves of and future prospects for these clays. Ball clays appear in ceramic formulas for manufacture of vitreous china sanitary-ware, electrical porcelains, floor and wall tile, dinnerware and artwares(l). This type of clay is used for refractory (2) and abrasive products(3), and as a suspending agent for ceramic glazes(4), engobes(5) and porcelain enamel slips(6). Although some ball clay is imported, probably 85-90 percent of ball clay used in the USA(7) is obtained from deposits in Weakley, Henry and Carroll Counties in Tennessee(8), and in adjacent Graves County, Kentucky(9). The term "ball", as applied to clay, probably derives from former mining practice in England whereby conveniently-sized blocks of clay were cut from moist clay beds by spading(10), The expression "ball" has no other technological significance. ASTM(11) defines ball clay as "a secondary clay, commonly characterized by the presence of organic matter, high plasticity, high dry strength, long vitrification range, and a light color when fired." This, and similar(12) definitions, applies to English ball clays but is not satisfactory for many American ball clays. Geology of the Tennessee-Kentucky Ball Clay Deposits Figure 1 shows that most commercial clay areas of the eastern United States lie near the edge of the Coastal Plain; a skew-shaped configuration of its landward boundary outlines the Mississippi Embayment(13), Near the apex of this basin a broad plain, with a rolling, Bullied topography(14), dips gently westward from the Tennessee River to bluffs at the edge of the Mississippi River flood plain.

Jan 1, 1972

By K. L. Gabby

Selective removal of mercury from cyanide leaching solutions while retaining silver has been a long-standing problem, due to the chemical similarity of mercury and silver. In order to be practical, a mercury removal process needs to be both highly selective and use inexpensive materials. This paper reports the use of zinc sulfide (ZnS) as a precipitant for mercury. The mercury cyanide complex (Hg(CN)4 2-) undergoes a replacement reaction with the zinc sulfide, forming insoluble HgS, while the silver cyanide complex (Ag(CN)2 -) remains in solution. Under appropriate conditions, the separation of mercury from silver is nearly quantitative, with close to 100% removal of mercury, while nearly none of the silver is precipitated.

"A fire design innovation of the concrete lining of the Ohio River Bridges East End Crossing Tunnel has been developed. As a result from a fire suppression and tunnel ventilation system, the project design Heat Release Rate (HRR) was able to be constrained from 300 MW to about 50 MW. With this reduced HRR, concrete lining without passive fire protection may be acceptable, if the tunnel concrete lining will not result in explosive spalling during the designed fire event. Concrete explosive spalling test was proposed to verify this assumption. Since no standard concrete fire explosive spalling testing procedure exists, a project specific testing procedure was developed and fire tests conducted. From fire test results, it is concluded that the proposed tunnel concrete lining, in conjunction with the proposed fire suppressing and ventilation system, will not experience explosive spalling and does not require a passive fire protection system. INTRODUCTION The Ohio River Bridge East End Crossing Tunnel is part of a Public Private Partnership project, which connects transportation network between Louisville, Kentucky and southern Indiana. Located in Louisville, Kentucky, the twin-tube highway tunnel provides northbound and southbound lanes of the Kentucky approach to a new bridge across the Ohio River. Tunnel lengths are approximately 1,675-ft and 1,685 for the northbound tube and the southbound tube, respectively. Connected by two cross-passages, both tubes have a roadway width of 40-ft, for 3-lane traffic, and a vertical clearance of 26.5-ft.The Tunnel was constructed by drill and blast method with shotcrete and rock dowels as initial ground supports. The final tunnel lining consists of 16 inches cast-in-place concrete lining and 20 inches invert slab, with a waterproofing system around the tunnel perimeter. Two (2) tunnel side drains and one (1) invert drain were provided for each tube. This paper describes the rational in assessing fire design requirements of the tunnel final concrete lining, to answer the question whether a passive fire protection system is needed or not."

Jan 1, 2016

By T. R. Ley

"INTRODUCTION Brutally honest mining executives will tell you that “safety is job #1 but.. dollars are also extremely important”. When economic times are tough, as they are now in mining, it can feel like you need to choose between safety and cost control. Leading edge companies know that it is excellence at both that provides the best performance. FLUID POWER SYSTEMS Fluid power systems are ubiquitous in mining – longwall systems, continuous miners, drills, haul trucks and excavators, etc. And fluid power systems are getting more powerful and using higher pressures to move greater volumes and achieve higher productivity. Average operating pressures in mobile equipment has been rising to 450 bar (6,500 psi) over the last decade. With increased system pressure comes ever increasing levels of stored energy. Stored energy that, if released in an uncontrolled fashion, can do tremendous harm to people and things.Fluid power systems are composed of pipe, flexible hoses, pumps, valves and actuators. They are filled with fluid (mineral oil or fire-resistant) to transmit power to where it’s needed for performing work. With time and use fittings can loosen, component performance diminishes and hoses wear and tear. In hostile environments, like coal mining, hydraulic hoses can fail in as little as 2 years according to DGUV (umbrella association of German Accident Insurers), maybe sooner in some particularly challenging environments. FLUID POWER SYSTEM SAFETY While appearing simple and benign on the surface, fluid power systems, particularly such systems on mobile equipment, have many potential hazards. Hazards that most workers aren’t aware of – particularly young, new hires. And those hazards that can quickly turn deadly. During the past couple of years, including at last year’s SME Conference, I talked to a wide variety of mining people about high pressure fluid injection injuries. Some people, often with little or no field experience, never heard of it. But, people with mine operations / maintenance experience were almost always aware of such injuries.Some had even seen it happen right in front of them. But most claimed it didn’t happen all that often. It just wasn’t seen as a problem!"

Jan 1, 2016

By R. E. Vivas, J. A. Villa

"Located in the state of Colima, Peña Colorada is one of the largest iron ore operations in Mexico. The project is owned in equal parts by ArcelorMittal and Ternium. Though boasting a production capacity of 4.1 Mt/a (4.5 million stpy) of concentrate per year, Peña Colorada is faced with declining ore grades. In order to respond to this situation, Peña Colorada had to expand production even further. This expansion created various challenges that were overcome by the adoption and application of new technology. Examples of these technological innovations are discussed in detail in this article and include improvements in geo-modeling, mine planning, and mine operations. The successful implementation of these technologies paid for itself many times over, and has led to significant improvements in production and performance, while lowering the operating costs and reducing the variance between planning and execution.Project overviewPeña Colorada is a mining company that produces about 30 percent of the iron ore in Mexico. This project generates about 1,200 direct jobs and 3,000 indirect jobs, making a significant contribution to the local economy. Similarly, Peña Colorada invests in its local communities through numerous educational programs, scholarships, university agreements, social development, environmental agreements, etc. Peña Colorada’s operations consist of an open pit mine located in Minatitlán and a pellet plant located in the port city of Manzanillo, as shown in Fig. 1. Technological innovationsMost mining projects around the world typically follow the logic of “mining the next best ore.” Consequently, head grades tend to decline over the life of the mine. In the case of Peña Colorada, a decline in head grade combined with a decline in iron ore prices forced the operation to adapt to a new business environment and adopt new technologies to face these challenges. However, the first step along this process was to increase the confidence and reliability of the resource model. This task involved additional drillhole campaigns coupled with more detailed modeling techniques. Once the block model was completed, new optimization studies and production schedules were evaluated with new optimization tools that improved many aspects of the mine plan. The Peña Colorada block model has undergone 3 expansions to reflect additional information not available in the past. The model has expanded to the East and Southwest. The latest model expansion increased the total number of benches to 98 as a result of positive exploration results. Similarly, new geotechnical studies were prepared, which provided new guidelines for pit slope design, and new technology was implemented to monitor ground movement and slope stability. Two sectional block model views in Hexagon Mining’s MineSight 3D, along with the pit designs and geologic solids are shown in Fig. 2."

Feb 1, 2017

By Mustafa Akser

The Pipestone Lake anorthosite complex in Manitoba, Canada, was recently been re-identified as a potential source for titanium, iron, and vanadium. The present study utilized a 350 kg hard rock sample, which originated from the "Main Central" zone of the deposit. Commercial pilot-size equipment, such as dry low intensity roll magnets, wet high intensity magnets (WHIMS), and high tension electro-dynamic roll separators, was employed. As products, ilmenite up to 48.5% TiO2, and magnetite concentrates up to 87.9% Fe3O4 with 5.25% TiO2 were obtained. The majority of the vanadium reported to the magnetite concentrate. Subsequent characterization of various separation products shed light on the potential grade and recovery of the minerals from this deposit.

Jan 1, 1996

By Michael D. Loy

This paper examines the computerization steps of United Coal Company of Bristol, Virginia. OVERVIEW Producing close to 7,000,000 tons per year, United Coal Company is one of the most interesting mining companies in the east. Their approach to mining reflects a dedication to modern technologies and extraction methodologies. With varying amounts of production coming from four divisions (a fair amount of production comes from contract operators) and over a billion tons in recoverable reserves, United rests heavily on the planning and engineering efforts of a centralized engineering group. Although each division relies on its own engineering personnel for day-to-day management and operations, long range planning and reserve management is conducted at the corporate engineering level. This group, while extremely competent and efficient, is relatively small (7 people), when compared to the needs of a large mining company.

Jan 1, 1985

By S. R. Stine

The Cyprus Thompson Creek Mine is located at 2,286m (7500 feet) elevation in the Central Idaho mountains, 61.16 kilometers (38 miles) southwest of Challis, Idaho off State Highway 75. The Thompson Creek molybdenum deposit lies near the eastern border of the late Cretaceous Idaho Batholith within a complexly deformed sequence of Paleozoic sedimentary rocks. Molybdenum mineralization is contained in a composite biotite granodiorite-quartz monzonite stock considered to be genetically related to the Idaho Batholith intrusive event. The ore is being mined by open pit methods and delivered to the concentrator stockpile with an overland conveyor belt system. The concentrator is designed as a 22,680 metric tons (25,000 ton) per day plant at an average head grade of 0.1% Molybdenum.

Jan 1, 1986

By K. Chandrasekaran

Carbon-in-Leach (CIL) is conventionally used in gold processing operations when preg robbing components are present in the ore. CIL process is becoming attractive even in other situations when preg robbing is not a factor. This paper discusses the situations in which the CIL circuit can be applied. The results of Leach/CIP and CIL circuits at Newmont's Mill No.2, 4 and 5 are presented for comparison. Newmont's Mill No. 4 was initially designed for a throughput of 4500 tons per day. The mill is presently operating at an average throughput of 7300 tons per day without significant changes to the original design. The design considerations of the Mill No.4 CIL circuit are discussed.

Jan 1, 1991

By Kal V. S. Sastry

Conventional iron ore balling circuits exhibit undesirable surging behavior which is known to result from uncontrolled occurrence of the mechanisms of nucleation, coalescence and layering. This study was undertaken to investigate the mechanism of pellet growth by layering. Several laboratory experiments have been carried out to delineate the effect of feed moisture content and feed quantity. This paper presents an analysis of the experimental results and a simple model to describe the layering process.

Jan 1, 1993

By D. J. Wood

BHP Copper has grown, in just over six years, from a minor participant to the world's largest privately owned copper producer. BHP Copper's major asset is the world's largest copper mine -Escondida in Northern Chile. Ten years ago investing in Chile was considered high risk. Today, Escondida represents an investment of approximately US$2 billion. Reward is the result of managed risk and Escondida is a clear demonstration of both. The Ok Tedi copper and gold mine in Papua New Guinea represents a Rubicon of risk and a retrospective on reward in a developing country on the doorstep of a developed one. The story of these two mines encapsulates risk in the mining industry.

Jan 1, 1998

By Boris CARO VARGAS, Bernard Theron

"In early 2014, Nicholson Construction Company was awarded, together with its tunneling sister company Bessac, the Norris Cut Miami Tunnel Project. The 2.5-meters diameter segmental lined tunnel, 1600-meters long, is aimed to replace the existing 54” force main connecting the Waste Water Treatment Plant (WTP) on Virginia Key to Fisher Island. To overcome project challenges such as the highly permeable limestone of the Fort Thomson Karstic Formation (one of the most permeable formation in the World), the project team has developed State of the Art solutions: The TBM was launched with pipe-jacking technique for the first 70-meters and then converted to segment erection mode. It allows substantial schedule savings and drastically reduces the size of the circular launching shaft. The TBM, jointly designed and manufactured by Bessac and Herrenknecht, can convert from slurry to EPB mode within a few minutes. The cutters can be replaced by wet divers thanks to an innovative application in the TBM industry. PRESENTATION OF THE PROJECT The aim of this project is to replace the existing 54-inch force main pipeline which transmitted all sewage collected from Miami Beach, Surfside, Bal Harbour, Bay Harbor, North Bay Village and Fisher Island to the Central District Wastewater Treatment Plant (CDWWTP) to Fisher Island. The existing pipeline consisted of pre-stressed concrete cylinder pipe which is in poor condition in a number of locations and could be subject to sudden failure. An adjacent portion of this existing force main under the Government Cut (North Fisher Island) has already been replaced as part of a previous design-build contract and involved the installation of a 60-inch diameter fiberglass-reinforced mortar pipe installed inside a micro-tunneled casing."

Jan 1, 2016

By Wi11iam M. Leaders

Uranium Recovery Corporation was incorporated in the State of Florida in 1968 for the sole purpose of developing a method to economically recover uranium from Florida phosphoric acid. The preliminary laboratory work culminated in the demonstration of the process to United Nuclear Corporation in the spring of 1971. This was quickly followed by a pilot plant program to identify any unusual problems such as those arising from the day-to-day variation which occurs in a fertilizer phosphoric acid plant production system. After two years of pilot plant operation, United Nuclear Corporation purchased controlling interest in Uranium Recovery Corporation and committed several million dollars to the design and construction of the first commercial plant for this purpose in the State of Florida, or anywhere else in the United States, for that matter. After many start-up problems were resolved at the production plant located at the W. R. Grace fertilizer complex near Bartow, sustained production began March, 1971, and has continued to date. We still have some problems to solve but are currently producing sufficient uranium to make shipments to the UF6 converters for preparation of Florida uranium for use in nuclear power plant fuel materials.

Jan 1, 1978

By G. Van Weert

Refractory ores and concentrates containing silver tend to form Ag-jarosite during autoclave oxidation. Silver extraction from the oxidation products is therefore low, unless a hot lime treatment step to decompose Ag-jarosite precedes cyanidation. Since silver iodide is very stable but soluble in cyanide solutions, the formation and decomposition of Ag-jarosite in the presence of iodine species was studied. Results indicate that Ag-jarosite formation could be prevented in favour of H3O-jarosite and AgI while oxidizing Ag2S under industrial autoclaving conditions, when the total iodine species to Ag mole ratio exceeded 5. Lower ratios gave proportionally more Ag-jarosite and less AgI. Under these conditions existing Ag-jarosite was also found to decompose in H30-jarosite and AgI.

Jan 1, 1993

By T. Petrov

This study was performed to analyze the behavior of the blowing curtain face ventilation system modified with a specially designed regulator, called Wing Regulator. The purpose of the regulator is to extend the airflow penetration depth toward the face and allow effective face ventilation at curtain setback up to 13.7m (45ft) from the face. A small scale model of the Wing Regulator was successfully tested in the Mine Ventilation Laboratory at the University of Kentucky. Then a prototype of the proposed regulator was tested in full-scale in mine environment. Series of three dimensional simulations were performed to support this research using validated CFD code. This paper presents results of the performed studies and discuses the advantages of using the Wing Regulator. Presented information relates to the US Provisional Patent Application No 61/818,112.

Feb 23, 2014

By R. Hogg

Experimental studies of the axial distribution of particles along dry ball mills are described. The results, for mills ranging in diameter from about 10 cm to 1 meter and operated in both the batch and continuous modes, indicate a consistent pattern of significant migration of particles away from the ends of the mill. In some, but less frequent, cases axial migration of the grinding media is also observed. Analysis of the data suggests that particle migration results from end-effects which extend for a distance of about one mill diameter along its length. End-wall roughness appears to play a significant role in the particle migration phenomenon. Media migration is generally associated with continuous mills operating at relatively high powder flow rates.

Jan 1, 1994

By A. I. Johnson

The pegmatites of the Black Hills of South Dakota are the coarse-grained differentiates of the Harney Peak Granite. The Harney Peak Granite was intruded into the Pre-cambrian schist and quartzites and resulted in the Black Hills uplift. In the outer adzes of the granite intrusion occur the pegmatites. In the zoned pegmatites, representing the most highly differentiated portions of the parent magma, occur most of the minerals produced from pegmatites. These are of economic importance and they are the subject of this paper. The various mineral products will be taken up separately.

Jan 1, 1978

By D. R. Zeni

Current mine development requires the safe, 'expedient, economical construction of vertical shafts for ventilation and access in diverse ground conditions. Advancements in large diameter shaft drilling have lead to exceptional mechanical refinements of shaft drilling technology. The author traces the history of the equipment and methods employed by the large diameter shaft drilling industry and explores likely paths of future development. A few case histories are cited to illustrate the adaptability of shaft drilling as a versatile tool for advanced worldwide mining operations. Safety, schedules, cost, environmental impact, and capability are discussed to assist the mining engineer in the investigation of feasible projects.

Jan 1, 1994