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By Robert Rautenberg, Ted Budd

The paper will discuss the successful construction of the largest dollar value ($194.5 million, U.S.) TARP (Tunnel and Reservoir Plan) project built to date for the Metropolitan Water Reclamation District of Greater Chicago. The mining and lining of the 18.5km (11.54 miles) tunnels will be emphasized. The tunnels were driven utilizing three TBMs ranging in size from 9.85m (32.33 ft) to 3.70m (12.16 ft) in diameter. The operations surrounding the 11,546m (37,876 ft) long 9.85m (32.33 ft) diameter tunnel will be highlighted. A total system concept was utilized to attain mining rates up to 29.3m (96 ft) per shift and lining productions of 58.5m (192 ft) per day. The reliability of these systems was instrumental in the completion of the project more than a year ahead of schedule.

Jan 1, 1995

By Natesa Jayaraman, Jon C. Volkwein, Edward D. Thimons

The Bureau of Mines has studied the impact of shuttle car movement on face ventilation. Real-time measurements of air velocity, methane gas, and respirable dust were recorded and compared with a time study of face shuttle car movement. Work was conducted in a blowing face ventilation section where a scrubber-equipped mining machine operated. Air velocities decreased by an average of 35% as the shuttle car entered the face, restricting air flow, and increased by an average of 35% as the shuttle car pulled away from the face, drawing with it additional air. Return air methane levels follow the face air flow volumes, decreasing as air volume increases. The surge of air created as the shuttle car leaves the face helps to dilute methane. Respirable dust levels, however, were found to increase as the air flow increased and decreased the scrubber capture efficiency.

Jan 1, 1989

By Alan A. Campoli, Michael D. Zuber, Frank E. McCall, Gerald L. Finfinger

Injecting water under pressure to wet the coalbed in advance of mining reduces mining-generated respirable dust. Owing to economic and geological barriers, water infusion for longwall dust control in the United States is currently limited to the Pocahontas No. 3 Coalbed in Virginia. Water is pumped into the coalbed through underground boreholes drilled horizontally from the headgate toward the tailgate side of retreat longwall panels. This paper theorizes that the barriers to widespread utilization of water infusion for longwall dust control could be overcome by long-duration, low-pressure water infusion through vertical gob gas boreholes. Currently, 43% of the 72 longwall mines in the United States employ vertical gob gas boreholes. Computer coalbed reservoir simulation suggests that one vertical surface borehole could infuse the same longwall panel area as four horizontal boreholes in the current water infusion system for longwall dust control in the Pocahontas No. 3 Coalbed.

Jan 1, 1995

By James Veri, Andrew H. Stern, Gerald N. Torbert

When mining coal, the occurrence of high methane liberation rates can often overwhelm the existing ventilation capabilities of the working place and result in elevated levels of methane gas. These “gas-off/stand-by condition" events often limit the production of the section and increase the potential opportunity for the occurrence of an ignition. This paper investigates the potential effectiveness of using a continuous miner equipped with an integral dust scrubber which was modified to provide high flow rates to reduce these events during active coal mining. Work was undertaken to quantify various adaptations of the mining system, by simulating site parameters in the controlled environment of an instrumented "full-scale" test facility. Monitoring (in real-time) of velocities and gas concentrations at many fixed points was also undertaken in an attempt to learn the effective limits of the system at high release volumes of gas.

Jan 1, 1997

By Michel L. Van Sint Jan, Gabriel Fernandez-Delgado, Edward J. Cording, James W. Mahar

INTRODUCTION Shotcrete behavior observed in subway tunnel construction in the U. S. has been primarily in blocky or blocky and seamy rock in which rock loads develop from the self weight of individual rock blocks that tend to loosen from the wall and roof of the opening. Such conditions can be classed as loosening ground, in contrast to squeezing ground in which high pressures are generated on the tunnel lining with time as the ground creeps under the natural ground stresses. In the philosophy often associated with the New Austrian Tunneling method, emphasis is placed on the use of shotcrete and other support elements in squeezing, highly stressed ground, in which the support system is designed to allow controlled movements so that high lining stresses do not develop. In contrast to these conditions, the concern in loosening ground is to provide support soon enough to minimize loosen-

Jan 1, 1979

By Arpad E. Torma

The introduction of biotechnological principles in hydrometallurgy has created new opportunities and challenges for the industry of mineral processing. During the 1950's and 608s, the mining wastes and unused complex mineral resources have been successfully treated in bacterial assisted heap and dump leaching processes, especially for the production of copper and uranium. The economic viability of bio- leaching technology lead to its world-wide acceptance by the mining industries. During the 1970's this technology grew into a more structured discipline which is called "biohydrometallurgy". Currently, bioleaching techniques are ready to be used, in addition to copper and uranium, for the extraction of cobalt, nickel, zinc, gold and silver from diverse mineral resources and for the desulfurization of certain coals. However, in a foreseeable future the biohydrometallurgical processes may be applied also for the treatment of high- grade ores and mineral concentrates using native and/or genetically engineered microorganisms.

Jan 1, 1989

By Paul J. A. Lever

The mine environment is dynamic and operating conditions change continually and are difficult to predict. New equipment, variable geological conditions, modified layouts, and different equipment operators make monitoring and control system difficult to apply without continual software maintenance. The paper reports on algorithms that were developed, encoded with Knowledge Craft Tools, and tested on underground coal mine data to adapt to the dynamic environment. The system receives data from sensors in near real time and then identifies patterns in the data. Using a set of mode features the data is automatically checked to determine the present operating mode. When the operating mode changes from the previous shifts, the system automatically learns the new mode characteristics and uses that mode context for further data analysis. The concepts presented in this paper are applicable to a wide variety of mining scenarios, not just underground coal mining.

Jan 1, 1992

By Jim Merza

The recent heightening of environmental issues has forced more and more mining operations to focus on developing new methods to control dust problems encountered at their concentrate dryers, stock piles, tailings ponds and during the loading, transportation and unloading of their products. The development of dust control agents requires a quick reliable and most of all accurate method to evaluate the performance and to optimize the formulation of these products in the laboratory, thus avoiding expensive field trial evaluations. This paper gives an overview of the industry requirements for specialty dust control agents, application techniques and current laboratory evaluation procedures. The paper will also outline the development of a unique dust suppression testing apparatus called the "Dust Box, which is used to evaluate chemical dust suppressants at the laboratory level. Laboratory results from two test programs on different substrates are presented in the paper.

Jan 1, 1994

By N. S. Tanious

The accuracy of vibrating wire stress meters has been questioned by various users in the mining industry. During an in situ coal pillar study, a laboratory evaluation program was developed to determine whether stress meters could produce reliable measurements in coal. More than $0 stress meters were tested for accuracy, repeatability, effects of setting pressure, and the concept of using a single curve for interpreting the stress-meter data. The testing medium was lucite, a material with a modulus of elasticity very similar to coal. The evaluation demonstrated that the stress meters did provide repeatable measurements, but that accuracy was lacking when the recommended interpretation technique was used. Therefore, a new technique was developed that required all stress meters to be calibrated in the laboratory before use in the field. This new technique reduced the average error to typically less than 10% and, in the worst case, to below 15%.

Jan 1, 1988

By J. Girard-Dwyer, J. Johnson, J. Whyatt

The choice of fragmentation method is one of the most fundamental aspects of mine design, and often has a major impact on the safety and economic viability of an operation. Almost exclusively, underground mining operations rely on either mechanical excavation or drill and blast techniques to extract rock. Each of these fragmentation methods has distinct advantages and disadvantages, and each is appropriate, and economic, for different mining conditions. However, the choice of fragmentation method can have a pronounced effect on the amount of damage created in the rock mass surrounding the opening. This paper reviews a number of case studies where both mechanical excavation and traditional drill and blast were used in underground mines. Ground support requirements in the mechanically excavated areas are compared to the support requirements in the blasted sections in order to demonstrate the potential safety and cost benefits of the various fragmentation methods.

Jan 1, 2003

By C. O. Brawner, A. Bellamy, D. S. Cavers

Pit slope designs at Nickel Plate Mine have used relatively steep interim and final wall slopes of 60 degrees overall. The rock is unusually strong and tough with most discontinuity sets being steeply dipping. An integrated program of monitoring and drainage has been used. Stopes of large extent which are generally unsupported occur on the property. For the most part, no deterioration of the stability of the stopes has occurred over the last 30 or more years. Mining methods through these areas have used a combination of fill s placed via VCR drop raises and crater blasting of the backs. One of the major challenges in mining through the stope areas is to maintain slope stability conditions and to reduce dilution of the higher value ore zones occurring immediately around the stope areas. The paper discusses geology, slope stability and mining methods at Nickel Plate Mine.

Jan 1, 1988

By T. Negeri

The simultaneous use of two or more families of collectors can sometimes improve one or more key flotation performance indicators, especially if the ore under consideration contains several minerals bearing the same metal. The maximum amount of collectors that can be used is limited by the need to maintain a high concentrate grade and selectivity. Therefore, when more than one collector is required, an experimental design that allows variations of both the proportions and the amounts with respect to other process factors has to be selected to find the optimum dosage. This type of design is known as "process factors in mixture amount experiment". It is a powerful design suitable for discovering the existence and evaluating the magnitude of the interactive effects between various flotation parameters. This paper elaborates the principles on which such a design is based, and demonstrates its usefulness with a case study.

Jan 1, 2003

By R. T. Swindeman

"INTRODUCTION This paper will discuss the topics in the recently released Conveyor Equipment Manufacturers Association’s (CEMA) Belt Conveyors for Bulk Materials, 7th edition, that deal with safety and maintenance. The most effective way to improve conveyor safety is through designing out hazards in the earliest stages of a project. When the safest way to perform maintenance is also the easiest, mechanics will naturally take the obvious and least hazardous approach. IMPORTANCE OF ACCESS Studies have shown that mechanics spend almost one-third of their time accessing the components to be serviced and approximately 25% of all fatal conveyor accidents occur during maintenance1. Chapter 2 of Belt Conveyors for Bulk Materials deals with design considerations. In Chapter 2 there are recommendations for access at the various sections of a typical conveyor for cleaning, inspection and maintenance. While, in some cases, providing access will increase the cost of the conveyor system there can be significant paybacks in reduced injuries, faster maintenance and easier cleaning. Piping and Conduit One of the significant recommendations in Chapter 2 for access is to restrict the mounting of piping and conduit to the conveyor structure in the Loading and Discharge zones of a conveyor. Piping and conduit are more permanent fixtures than maintainable components and should be located out of the way of components needing frequent maintenance. If electricians and pipe fitters are given convenient locations to make their runs they will natural use them. Flexible conduit and hoses can be used to connect to components from pipe racks and cable trays which further enhances maintenance. Access for Cleaning Another critical aspect of access is for cleaning. Approximately 33% of all fatal conveyor accidents occur while cleaning spillage and carryback under and around conveyors2. In the loading zone having sufficient height under the conveyor for cleaning increases the cleaning interval and allows for safer cleaning. In the discharge zone having adequate access for belt cleaning installation has a direct effect on the ability to install a proper cleaning system and perform maintenance."

Jan 1, 2015

By Mark R. Rybak, James Delmonte, Travis Hartman

The City of Phoenix, Arizona designed a 7.2 km (4.5 mi) long water transmission main from the South Mountain Reservoir to the Ahwatukee Foothills Reservoir to address the growing demand for drinking water in the southeast valley. The pipeline design called for a bored tunnel in a very environmentally sensitive area. The Reach3B contract included an 2.44 m (8 ft) diameter TBM excavated tunnel, 1,847 m(6,060 ft) in length. The geotechnical investigation revealed that the tunnel would likely pass through zones of loose to moderately cemented soils (caliche). The primary tunnel support would consist of rock bolts, circular steel ribs, hard wood lagging, and mine straps. A TBM that could handle the ground conditions and allow for efficient ground support installation was required. This paper describes the construction of a small diameter rock tunnel in challenging ground conditions.

Jan 1, 2003

Dunn has written an excellent paper providing a wealth of advice on what is often the most costly consumable in the mineral processing plant. As he pointed out, grinding media selection and quality control can play a major role in successful plant operation. Owing to the economic importance of this topic, there are some important factors related to media sizing that I believe merit further comment. Dunn made reference to a slightly simplified version of the Azzaroni (1981) equation and pointed out its successful use for the Henderson SAG and Climax ball mills. Although both formulas are empirically based on successful plant experience, a notable discrepancy between them is that Bond has factored the work index by the ore specific gravity. This is invariably so, as the Bond work index is derived from the mass grindability (in grams per revolution) measured in a test mill with a fixed volume of solids load (Bond, 1961). A material having the same structural integrity but double the density of another will have double the grindability and just over half the work index. Thus, for the general case, specific gravity should be incorporated into any media sizing formulation that uses work index as the criterion for resistance to breakage.

Jan 1, 1990

By Gary D. Babbitt

Facing an orchestrated assault from the anti-mining lobby and its congressional allies, the Mining Law of 1872 may soon be either dramatically changed or even repealed. In 1989, Sen. Dale Bumpers (D-AK) introduced Senate Bill 1126 entitled the "Mining Law of 1989." It has been through several hearings and is still in the Senate Committee on Energy and Natural Resources, where Sen. Bumpers is the number two ranking Democrat. In the House, Rep. Nick J. Rahall (D-WV) introduced the "Mineral Development and Exploration Act of 1990," HR 3866. This bill is in the House Committee on Interior and Insu¬lar Affairs. (The numbers on these bills, and perhaps some of their language, will be changed when they are reintroduced in early 1991. However, their substance is expected to remain substantially unchanged. Bill numbers here refer to legislation as it was numbered in the 1990 Congress.) In the eyes of its supporters, Bumpers' S 1126 appears to be more complete and has the inside track over the Rahall bill. Bumpers' bill includes provisions for royalties, bonding and reclamation. The Rahall bill is criticized by opponents of the Mining Law for its failure to include a royalty provision and for not having specific bonding and reclamation provisions.

Jan 1, 1991

By S. G. McDowell

Automation techniques are used during the design stage of continuous miners to decrease the time required and ensure the accuracy of the design. This is followed by automated manufacturing processes to reduce manufacturing time and improve the quality and consistency of parts. Combined, the result is a more reliable machine that can provide ongoing production capability. With the use of automation to enhance operator effectiveness and monitor machine condition, the productivity of machines is also improved. Productivity of continuous miners doubled over a 10-year span (Fig. 1). Although this article focuses on the continuous miner, it should be recognized that production increases of the continuous miner would not be realized without increased capabilities throughout the rest of the mining system. There are several aspects of automation that have played a role in providing increased continuous miner productivity. Though some are considered indirect, they still had significant influence on the overall result. Basically, productivity increases are obtained by cutting, loading and transporting the coal at a maximum rate. In addition, these tasks must be consistent, with minimal downtime. Therefore, the miner had to improve in operational capability and reliability. Automation techniques used during machine design, manufacturing and operation have all played significant roles in achieving higher productivity.

Jan 1, 1991

By N. S. Tombs

This paper presents the experimental results of an ongoing investigation into various properties related to the performance and durability of concretes made using existing and new cement replacements. The process of cement and concrete production is investigated focusing on product performance and environmental performance. The overriding factor for the progression of a material will be product performance however; each material selected will have many intrinsic environmental benefits. The study combines Ordinary Portland Cement (OPC) with each cement replacement candidate using the most common replacement percentages, 10, 20, 25, 30 and 50 percent. A 35N/mm2 concrete is then prepared and analysed in the fresh and hardened state. In addition, a chemical and physical analysis of each replacement material has been performed and results compared to the control samples containing OPC only and Ground Granulated Blast Furnace Slag (GGBS) as a replacement. The results show that in their present form the replacements used in this research do not compare with the strengths achieved by the controls. The right balance of chemical composition and particle grading needs to be achieved to produce a realistic replacement material. The processes required to achieve this must strike a balance between monetary and environmental cost.

Jan 1, 2006

By J. Loredo

In some rural regions of Peru, artisanal gold mining is currently an essential activity as it provides an important source of income. In the Huanca region (Ayacucho Department) gold deposits are not attractive for mining companies due to their reduced size, but they have enough interest for artisanal mining because of the ease and low cost of mining operations. Artisanal gold mining represents an important damage for the environment, because operations related to amalgamation processes using Hg result in special environmental problems besides the typical ones commonly associated to all mining activities. A preliminary sampling has been made in soils, materials from tailing ponds and surface water of the Acarí River, at the site of the Huanca village, according to networks specially designed for the particular conditions of the area. Studies accomplished revealed high mercury concentrations in soils and tailings. Chemical analyses of soils directly collected in the area of the active or abandoned ?quimbaletes? show mercury concentrations ranging from 15.3 mg?kg-1 to 44.2 mg.kg-1. Mercury concentrations in soils decrease as a function of distance from the before mentioned sources. Water quality of the Acarí River that flows through the area does not present important changes as a consequence of the mining and processing operations.

Jan 1, 2006

By Rolf J. Wesely

Recent events in The Peoples Republic of China indicate that a major effort is underway to increase trade with the western world. Gold production contributes to China's ability to participate in international trade. Consequently, the Chinese government places a high priority on increasing gold production. Many of the operating gold mines in China contain refractory ores that to date have not been efficiently treated. Figure 1 illustrates the description and location of a few of China's major gold mines. China recognizes that the technology necessary to economically treat this ore has been developed in the United States and other western countries. The country has therefore begun to seek assistance in evaluating several potential projects. Organizational structure Gold mining and processing in China is directed by the China National Gold Corp. (CNGC), headquartered in Beijing. The agency has a director in each province who is responsible for exploration, mining and processing. CNGC uses the services of two engineering organizations for metallurgical testing, process development and design engineering for their projects. The largest engineering organization is the Central Engineering and Research Institute for Non-Ferrous Metallurgical Industries (ENFI), also located in Beijing. The second engineering organization is the Changchun Gold Design Institute (CGDI), located in Changchun Jilin province.

Jan 1, 1993