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By T. W. Mattioli

Restrictions on fugitive emissions and crushing operations continue to get tighter. Although fugitive dust control in the gold mining industry has historically been difficult, there are now several options that can make dust control both effective and efficient. Using new technology, mine operators can now design and maintain a dust control program that can reduce product losses, decrease equipment failure, cut cleaning costs, and meet air quality compliance standards as well as provide a better working environment. This paper discusses the sources of fugitive emissions related to the gold mining and crushing operations and describes effective new control methods.

Jan 1, 1998

By W. A. Rickelton, A. J. Robertson

The ability of triisobutylphosphine sulfides to selectively recover silver from acidic sulfate solutions containing zinc and copper is described. Selectivity is explained in terms of the concept of hard and son Lewis acids and bases. Silver is stripped from the solvent using a novel strip feed (thiosulfate salt), and the recovery of metallic silver from the strip liquor by electrolysis or cementation is suggested. The high selectivity of extraction for silver and the utility of the stripping reagent are demonstrated in continuous, countercurrent, mini-plant tests. Important reagent properties, such as hydrolytic stability and low aqueous solubility, are discussed.

Jan 1, 1988

By Romeo Jurani, Ralph Dresel, Fred Kissell, Charles Parker

This report describes actions taken to control silica dust at the Yucca Mountain Exploratory Studies Facility (ESF), a tunnel located in Southern Nevada that is part of a scientific program to determine site suitability for a potential nuclear waste repository. The rock is a volcanic tuff containing significant percentages of both quartz and cristobalite. Water use for dust control was limited because of scientific test requirements. A major dust reduction was achieved with an intermediate air cleaning station located on a rear deck of the TBM trailing gear.

Jan 1, 1999

By John H. Fowler

The 30th Forum on the Geology of Industrial Minerals will be held in the historical seaside city of Halifax, Nova Scotia, from May 22 to May 27, 1994. The Forum will be co-hosted by the Provinces of New Brunswick and Nova Scotia, two of Canada's East Coast Provinces, both having a long tradition of industrial mineral production. Two previous Forums, the 19th in Toronto in 1983 and the 27th in Banff in 1991, offered delegates the opportunity to see industrial minerals in central and western Canada. The 30th Forum will take you to Canada's east coast completing the picture of Canada's industrial minerals from coast to coast.

Jan 1, 1995

By Gary English

"Tunnel safety is evolving as science, engineering and technology make advances. Applicable safety codes and standards simply do not cover all the potentials of design, construction and operation. This paper reviews a series of tunnel projects code gaps in Seattle USA that were uncovered during the design and construction of a new highway tunnel, conversion of bus tunnels to combined road and rail tunnels, new rail tunnels using TBM and NATM, conversion of a road tunnel to light rail, and retrofit of an existing road tunnel to add lanes and improve safety systems. The perspectives of the ‘fire code official’ (Authority Having Jurisdiction) on methods to identify and resolve gaps in safety code and standard regulations, while garnering the consensus of the owner, designer, and contractors are presented. Additionally, the emergency responder command perspective on safe tunnel design, tunnel rescue during construction and operational safety is explained TUNNEL SAFETY EVOLUTION The underground has become nearly the only option to provide essential transportation corridors to continue our economic growth in key global areas. Tunnels are not built on a whim. Often significant portion of a regions wealth are invested to meet current, and hopefully future transportation demands. There are more transportation tunnels being built now than at any time in the planets history. The location of these tunnels is often selected for us based upon regional demand. Most commonly under densely populated urban centers and between populations’ centers to bypass geologic conditions like mountains and water bodies. Tunnels are being built in unforgiving soils, between tectonic plates, in extremes environmental conditions and often, under the very heart of the highest density population centers on the planet. All of these locations can bring with it conditions that challenge our common assumptions about safety. These extraordinary locations and soils create risks for both those constructing the tunnel, and in design engineering to meet the ‘minimum’ requirements at the lowest costs. There is lengthy history of above ground safety. Most countries and major local jurisdictions have adopted, or created safety requirements for the construction of above ground buildings. Through decades of use, these safety requirements have evolved, changed and been expanded to cover a wide gamut of actual and potential safety risks. However, the use of the underground for tunnel transportation corridors has grown exponentially with limited attention to safety requirements."

Jan 1, 2016

By J. G. Wargo

Disseminated gold deposits are the object of major search and development efforts by many mining companies throughout the world. The invention of more advanced equipment for open pit mining and and use of heap leaching methods, taken together with favorable gold prices has led to rising profits in the gold mining industry.

Jan 1, 1988

By E. G. Kelly

Because of the nature of the breakage in the Barmac vertical spindle impactor, the 80% reduction ratio is very small, so that when the energy efficiency is calculated by Bond's method, it appears to be very low. However, the product size distribution contains a high proportion of fines. It is argued that the production of these fines accounts for the high energy consumption, and Bond's method is modified to account for this, by considering the crusher to be, effectively, a number of smaller crushers in parallel, each having a different reduction ratio.

Jan 1, 1988

By Deepak Malhotra, Robert Dorfler

Modern engineering mill design has been refined over the years to the point where detailed ore and process specification criteria can be developed In the engineering design phase of the project. The plant Is then built to the detailed criteria and performance acceptance tested by the owner to see if the as-built mill meets the criteria, This performance testing is critical to the owner; the test must be systematic with sample collection coordinated throughout the plant. Despite the availability of systematic approaches to plant development, the new plants often fall short of design criteria. This paper discusses the key Issues a Project Manager/Process Engineer should Implement to ensure that plants meet design criteria.

Jan 1, 1991

By R. Asmatulu

A method of improving the efficiency of solid-liquid separation during centrifugal filtration has been developed. It consists of increasing the pressure drop across the filter cake using extraneous means such as pressurizing a filter chamber. This method, which may be referred to as hyperbaric centrifugation, is designed to increase filtration rate during the drainage cycle and, hence, to produce drier cake. In the present communication, the results obtained in a series of batch centrifugal filtration experiments are presented. The results obtained on fine coal and mineral samples show that cake moistures are approximately 50% lower than the case of using ambient pressure.

Jan 1, 2004

By Debbie Nakamura, Daniel Tempelis, John E. Shamma

The Metropolitan Water District of Southern California established a Board of Consultants to assist them in administering the design and construction of the Inland Feeder Program tunnels. The Board acts as an expert review body for the owner, looking at key issues that can potentially impact the success of the program. The use of the Board evolved over the life of the project, and its composition was modified to better address the needs of the owner, and the Program requirements. The experience, function, and value of such a board is analyzed and discussed in this paper.

Jan 1, 2003

By Haia Roffman, Amiram Roffman

A gas company operated more than 100 distribution stations. Mercury filled manometers were used for years in these stations to measure the flow of natural gas through the system. Use and handling of these manometers resulted in mercury spills and ground contamination. To assess the human health and environmental effects of these spills and the need of remediation, it was important to determine mercury specific species present and their concentrations. Soil samples were analyzed for total mercury, methyl mercury, inorganic mercury and elemental mercury. These analyses served as important input in the risk assessment performed for these stations.

Jan 1, 1998

By J. Litsenberger, T. E. Marshall, L. Burke, R. Melville, A. T. Iannacchione

Excessive levels of horizontal stresses cause ground fall hazards in underground mines in the Appalachian Basin. At an underground stone mine in Pennsylvania, a modified stress control mine layout is reducing the hazardous conditions associated with excessive horizontal stresses. A microseismic monitoring system is in place to measure levels of rock stability and provide information on the effectiveness of the design technique. The microseismic data is supplemented with frequent and extensive mapping of roof falls and roof rock damage. Findings to date show that the stress control layout provides more stable conditions and thus a safer environment for the mine workers.

Jan 1, 2001

By A. G. Sciulli, G. P. Ballock, G. Hearnshaw, K. K. Wu

Waste disposal underground is the most effective method when viewed from an environmental aspect. As costs of other methods of disposal continue to escalate, the cost effectiveness of underground disposal during the mining cycle becomes increasingly attractive. The use of concrete for sealing abandoned mines has proved to be suspect when associated with a relatively incompetent adjacent strata due to its shrinkage characteristics. Complete failure of the plug has been known to occur in some instances. A more effective, cost competitive seal can be obtained using pneumatically stowed material and incorporating a polyurethane grout, which has greater adhesion characteristics than concrete. Injection of the surrounding strata and of the stowed material helps to ensure an impervious barrier and prevent the plug from moving when subject to high pressure heads. When properly placed, impervious seals cause the old workings to flood, raise the mine pool level, and thus eventually eliminate the potential for oxidation, which is the primary cause of acidity in the water

Jan 1, 1987

By K. C. Kane, D. L. Meredith, B. E. Davis, D. A. Stanley, O&apos

Computer control of the minerals beneficiation process is limited by a lack of adequate sensors to provide information on the current state of the process. Recent reduction in the cost of image acquisition and powerful inexpensive computers make use of computer vision as sensory input in process control a possibility. In the phosphate industry, the amount of apatite in phosphate tailings is estimated by inspection. For machine vision, a simple 256 x 512 color image of the tailings was captured via an inexpensive color video camera on an IBM PC. Initially, the image is converted to gray scale and displayed on an EGA color monitor. A program was written which identifies the different constituents of the sample by analyzing the gray scale levels for the digitized picture. In other instances the minerals are identified by their relative color intensities. The amount of each constituent is determined with good accuracy from the area it occupies on the image.

Jan 1, 1990

By Todd A. Duex

The Richmond Hill Mine has recently completed a reclamation plan to mitigate Acid Rock Drainage (ARD) which was identified at the toe of the former waste rock pile in 1992. Reclamation activities began in 1994 with the removal of ARD material from the waste rock pile and placement of this material in the former pit. This material was then isolated from the near surface environment by a low permeability capping system designed to minimize water and oxygen flow into the material. The capping system consists of, from bottom to top, six inches of limestone, 18 inches of low permeability clay liner, 4 and one-half feet of thermal barrier/drain layer, and six inches of topsoil. This capping system was completed in 1995. An extensive program is in place to monitor the effectiveness of the reclamation plan, and includes measurements on moisture content movement, temperature, oxygen content, and groundwater impacts. Monitoring has been ongoing since the completion of reclamation. This monitoring plan is demonstrating the success in isolating the material from the near surface environment and minimizing the impacts to the surrounding environment.

Jan 1, 2000

By E. D. Seymour

Minera Yanacocha operates a complex heap leach gold facility in the Northern Andes of Peru. Four leach pads and thirteen solution storage process ponds form an extremely complex system. Distinctly different wet season and dry season rainfall accumulations present unique challenges to the process water balance. Minera Yanacocha operates four excess water treatment facilities which discharge water to the environment at specific quality standards in order to maintain a balanced system. Numerous government agencies and non-government organizations are involved with the permitting, monitoring and control of the discharged water. Minera Yanacocha maintains a relationship with 65 villages and communities, with a population of approximately 29,000 people and the city of Cajamarca with approximately 100,000 residents. This paper provides a high level review of the system complexity, the water balance, the excess water treatment facilities and social aspects of solution management.

Jan 1, 2004

By T. M. Dyhr, T. E. Wilson

Although environmental management costs during mine operation depend on the size, type, climatic and geochemical conditions of operation, general cost categories are identified and mean values, as a percentage of total operating cost, are determined for coal and non-coal surface and underground mines (medium-size) with on-site beneficiation and tailings disposal facilities. Cost trends are charted from 1963 through the present.

Jan 1, 2004

By Fathi Habashi

ION FLOTATION was introduced by F. Sebba in 1959. This technique permits the recovery of metal ions from solution through the introduction of an appropriate cationic or anionic surface-active agent into the solution. The surface-active agent, called a collector, is added in stoichiometric amounts in relation to the metal content of the solution. It reacts with the metal ion to form an insoluble soap, and is levitated to the surface by gentle bubbling of air to form a foam which collapses into an insoluble scum. The optimum conditions for the ion flotation with soaps of C10-16, fatty acids are shown in Table 15-1. Baarson and Ray (1965) found that once the metal was completely precipitated as the hydroxide, as little as one hundredth the stoichiometric amount of the collector was required to cause complete flotation of the [ ]

Jan 1, 1970

By M. G. Ayat, B. C. Scott

Coal degradation is the breakage of coal particles to finer sizes due to the continuous forces of attrition and gravity to which coal is subjected during mining, handling, and preparation. The objective of this paper is to determine the extent of degradation that a coal slurry experiences when transported through pumps and pipelines. The examination of degradation results for a number of different coal slurries have indicated that the extent of breakage is dependent on the physical properties of coal and the time span of circulation. These results have also indicated that certain size fractions of coal are more susceptible to breakage than others.

Jan 1, 1987

By Jacob Feld

Introduction The best way to eliminate the possibility of rapid excavation in tunnel work is to start an argument between Owner Engineer and Contractor. And arguments are readily started when work is progressed without a frank open agreement on the rules of the game. Fifty years ago a tunnel contractor took a job to excavate and line a tunnel, providing all labor and materials under the guidance and continuous instruction of the Engineer who provided all survey work, checked each new heading and set the lines for the next round of drill holes, usually designed and ordered protective measures, kept record of progress and controlled payment for the work. In my first job in a tunnel, muck cars were loaded by hand and hauled by donkeys. Progress was, at today's criteria, not rapid. The Contractor or in the case of a large concern, his executive field representative was always at the site, knew most of his men by name, and there was a mutual feeling of respect between him and the Engineer in charge of the work. Misunderstandings were cleared up when they came up, expeditiously and fairly, even though satisfaction was not always expressed. The Owner came for the ground breaking and usually for the holing through shot. The Owner had full reliance on the Engineer's ability and integrity. The Engineer recognized the Contractor's expertise in being able to man the job and produce results.

Jan 1, 1974