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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 Kenneth R. Dickson, I. Michael Gowring, Gary M. Davey

The Kemano Power Tunnel is currently being constructed by a joint venture of Atkinson, Kiewit, and Commonwealth. The 5.73 m diameter, 16.1 km long tunnel is part of the Kemano Completion Project in British Columbia, Canada which is being developed by Alcan Smelters and Chemicals Limited. The discussion includes the refurbishment and development of Robbins TBM 189-229 previously used at Calaveras (RETC Proceedings, 1987), the logistics of conducting a tunneling operation in a remote area with adverse weather conditions, in addition to a description of the work and the performance details in the various geological conditions encountered to date.

Jan 1, 1991

By H. Suharyono, M. Lutsky, R. Hogg

Sediment consolidation in highly flocculated suspensions occurs only if the self-weight of the material exceeds its compressive yield stress. A simple model for sediment densification is presented and applied to the simulation of thickener operations. Measured relationships between sediment self-weight and the extent of consolidation are used to establish underflow densities. Supernatant turbidity data provide the information necessary to predict overflow clarity. It is shown that thickener depth can play a role in determining solids-handling capacity as well as dewatering performance. The application of the model to the design and operation of full-scale thickeners is described.

Jan 1, 1995

By R. C. Guimareãs

Serrana's deposit contains three types of ore: oxidized, micaceous and silicate-carbonate. The results presented refer to characterization and fundamental studies performed on fractions resulting from the purification of five samples from the silicate-carbonate type collected in the mine. Each type was purified and submitted to mineralogical characterization, zeta potential determinations, and microflotation experiments. The samples, with exception of the barite, are mineralogically complex and the selectivity between apatite and gangue minerals is poor. Under the current state of art, it is impossible to feed the plant with the silicate-carbonate ore, unless it is blended with the standard oxidized ore.

Jan 1, 2002

By M. C. Manderson

While the United States has been the world's largest volume producer and marketer of phosphatic fertilizers for many years, it has recently suffered heavy losses for a variety of reasons. While improved economic performance is expected, it is still at least a year or two away. But when recovery does manifest itself, it will likely yield only mediocre profits, due in part to the fact that about 50 percent of output is export-dependent. Therefore, there appears to be limited likelihood that profits will be adequate to justify the further outlay of large amounts of capital for expansion.

Jan 1, 1986

By V. I. Lakshmanan, P. D. Tackaberry

The use of activated carbon as an alternative to Merrill Crowe precipitation to recover gold from pregnant leach solutions is recognized. Recovery using activated carbon, however, suffers from the interference, due to organic fouling, clay content and increasingly from the presence of elements such as copper. Ion exchange separation technology is familiar to the mining industry (uranium) and its potential application to the gold mining industry is evaluated with considerable efforts by research workers in South Africa, Australia, and North America. The present paper reviews in detail the status of the research work that identifies potential opportunities.

Jan 1, 1990

By R. J. Wesely, A. D. Zunkel, Tracy B. Braun, Philip L. LeHoux

An overview of gold processing operations at Barneys Canyon Mine is presented with particular emphasis on ore agglomerating experience, leaching and metallurgical accounting practices, and carbon column plant operating approach. The mine, located thirty kilometers from downtown Salt Lake City, is just eight kilometers north of the Bingham Canyon copper mine. Mining was initiated in February 1989 and the first gold was poured in September 1989. Through year-end 1992, approximately 7 million tonnes of ore have been processed and 12,000 kg of gold have been produced. Gold recovery is in excess of 85 percent.

Jan 1, 1993

By L. W. Ashton

Geochemical exploration guidelines were developed from a study of 460 rock chip samples collected at nine disseminated gold deposits in Nevada. Obtaining high grade Au samples is difficult because gold content is extremely variable, even over 8 m (25 ft) distances. For reconnaissance sampling, pathfinder elements are reliable indicators with threshold values of 100 ppm As, 1 ppm Hg, and 50 ppm Sb. Arsenic is the most reliable of the three elements, being significantly enriched in all deposits. If the pathfinder threshold levels are reached with low Au content, more samples should be collected. Successful disseminated gold exploration requires large numbers of samples.

Jan 1, 1990

By Takahide Wakamatsu, Junji Shibata

Complex polymetallic sulfide ore deposits occur in Tohoku district, northern part of Honshu island, Japan. The ore is locally called "Kuroko” ( black ore ) and is compactly composed of fine grained sulfide minerals of such principal metals as copper, lead, zinc and iron. Currently one of Kuroko mill plants is producing such concentrates as copper, lead, zinc, pyrite, barite, and clay minerals, mainly employing differential flotation techniques. This paper describes briefly the progress of techniques in Kuroko processing over the past thirty years and also the present state of Kuroko processing and its challenges to be studied and overcome in the future.

Jan 1, 1989

By Heiskanen K., Koivistoinen P.

A common belief is that autogenous grinding suits itself only to certain oretypes. It is shown that properly designed autogenous grinding can be used even with very difficult ores with energy consumptions which are equal or lower than obtained with rod-ball mill grinding. The basic feature in the design is the large port grate developed by Outokumpu. The scale-up of the mills can be done on the basis of the base mill concept. It enables to compare different mill sizes and types. Simple scale-up equations are presented based on actual mill data and experimental work.

Jan 1, 1992

By Bruce H. Van Brunt, Danny L. Taylor

Estimation of local recovered tonnage and its grade above a cutoff is of paramount importance during the exploration and development stages of any mineral deposit. The spatial dis- tribution of grades as well as the cumulative distribution must be defined. In this paper, Probability Kriging, an estimator based upon rank order statistics and the estimation of the distribution of point grades within a panel, is applied to the Manhattan gold deposit. Mapping the conditional probabilities that estimated panel grades exceed a cutoff is useful to the understanding of the distribution of mineralization in a structurally controlled gold deposit.

Jan 1, 1989

By Thomas G. Johnston, Garston H. Blackwell

The development of a block model for a copper molybdenum ore deposit is described. The early use of the inverse distance power estimator, and later transition to geostatistics and kr iging, produced block models suitable for global reserve estimates. Because the global reserve was inadequate for routine mine planning, the production blast hole assays were incorporated into the block model, resulting in excellent local grade prediction. The on site use of small mini, and more powerful personal computers for estimating grades is described. The development of a computer aided, interactive graphic, mine planning system utilizing the grade block model is detailed.

Jan 1, 1987

By David Sugden

Intense, tropical weathering of Cretaceous-Tertiary sediments has developed similar laterites in distant areas of the Amazon Basin. In two areas, Trombetas and Paragomina s, bauxites of commercial potential arc found. The bauxite comes mostly from the lower horizon of the three component laterite. The laterite is overlain by a clay cover, possibly an integral part of the weathered profile. The laterites are found on almost flat plateaus with individual areas of up to 80km2. There is a close relationship between the morphology and the ldterites. The process of lateritization is allegedly Pliocence but probably continues today.

Jan 1, 1984

By Steve Crewdson

High tonnage hoisting of materials by vertical conveyors through deep shafts is a relatively new concept in mining that is proving to be effective. The development of the Pocketlift® belt by Metso Flexowell, located in Moers, Germany, enabled the installation of a deep shaft vertical conveyor in 2002. This application followed years of design and operational experience gained in medium-depth shafts around the world. The design, manufacture, installation and operational experience of an 1,818 tonnes capacity, 273 meters vertical lift, Pocketlift® belt system at the White County Coal Pattiki 2 Mine is the subject of this work

Jan 1, 2004

By Stephen R. La Brooy, Tong Deng, Pritam Singh, David M. Muir, A. J. Monhemius, G. W. Warren, E. Peters

The controlled addition of ammonia to cyanide solutions inhibits the leaching of copper minerals but extracts up to 80% Au using as little as 10% of the cyanide compared with conventional cyanidation of copper-gold ores. The solubility of copper minerals and copper speciation in solution is dependent on NH3, CN-, pH and Eh. Rotating disc and electrochemical studies show that gold is leached by a mixed Cu-CN--NH3 complex with either Cu(II) or O2 as oxidant. This complex is slowly oxidised to CuCN and Cu(OH)2 by air.

Jan 1, 1993

By Paul Mitchell, Clive Potter, Miles Watkins

Meldon Quarry is a seemingly rare occurrence of acid rock drainage (ARD) in a quarrying operation.4 With surface waters discharging to a tributary of a salmon-bearing river, it is subject to stringent discharge conditions. The quarry predates effective environmental management, and preventative, control and treatment measures were not implemented until relatively recently. However, retrospectively implementing standard preventative approaches at the site is costly, technically difficult and of uncertain benefit. This paper overviews the recent site history and introduces data from a demonstration by KEECO (UK) Limited of its Silica Micro Encapsulation (SME) water treatment technology.

Jan 1, 2000

By W. M. Pytel

A simplified two-dimensional model to analyze time-dependent load distribution and surface subsidence associated with longwall mining geometries is described. The model is based on the theory of beams resting on inelastic foundations and includes visco-elastic behavior of immediate floor strata, non-linear behavior of coal pillars, elastic behavior of face supports, and visco-elastic behavior of the overburden strata. The relative importance of the different variables affecting the performance of longwall mining geometries from ground control point of view is also analyzed. The model has been validated for field observations from one Illinois longwall mine.

Jan 1, 1986

By T. Hart

Nuclear gauging is used world-wide in almost every industry. From mining and ore-grading to finished product, the metallurgical industry is one of the biggest users of nuclear sensors for inventory, process control, and quality assurance. This paper will discuss the basic theory of gamma transmission gauging techniques found useful in mining, milling and metal production. Techniques to be discussed are gamma transmission for level and density. A major new technique will also be discussed. This technique is called gamma backscatter. The uniqueness of this technology, how to apply and the differences between transmission and backscatter will be accentuated.

Jan 1, 2011

By Joseph J. Diehl, Brian B. Khalighi

This paper discusses the Queens Water Tunnel, No. 3, Stage 2, being driven by a new Robbins High Performance (HP) Tunnel Boring Machine (TBM).The paper is divided into four sections. In the INTRODUCTION section, a short overview of the scope of the project is presented. In the GEOLOGY section, the geological condition along the tunnel drive is briefly introduced. The TBM DESIGN section discusses the various design criteria and the resulting machine specifications. The paper concludes, in the TBM OPERATION section, with a case history describing the tunneling operation from start-up to the time of the writing of this paper.

Jan 1, 1997

By Ben V. Petersen

Surveying is to tunneling, as a steering wheel is to a car—somewhat essential if you want to end up in the right place. The principles of tunnel surveying have remained unchanged since the first tunnels were constructed: To mathematically connect the selected start and end points of a tunnel and physically translate that alignment onto the ground. The alternative is just dead-reckoning and leaves the probably less than satisfying end results to chance. Today’s laser-guided tunnels often have to thread the needle through a maze of soil types, utilities, structural features and other underground considerations. Surveying makes it possible.

Jan 1, 2005