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By W. Pariseau, J. Goris, S. R. Dismuke

Ore at the Magmont mine in southeast Missouri is extracted by the room-and-pillar method on two and sometimes three horizons. In 1991, a plan was formulated to recover high-grade ore in pillars using cable halts to accommodate spans of more than 27 m (90 ft ). A test area was selected and a recovery plan developed. A cooperative rock mechanics study was established by Cominco Metals, the US Bureau of Mines and the University of Utah. When initially opened in 1968, the planned production rate was about 910 kt/a (1 million stpy). Due to declining reserves, the production rate was decreased in November 1992 to 570 kt/a (630.000 stpy). Pillar recovery now accounts for about 40% to 50% of the mined tonnage. This method plays a vital role in allowing Magmont to continue to operate.

Jan 1, 1996

By Michael J. Rinker, R. V. Nicholson

Waste rock and tailings from a proposed nickel-copper mine were evaluated extensively for potential on-land and under water disposal. Standard humidity cell and column tests were conducted over a two year period and underwater tests were conducted for more than one year. Nickel concentrations or release rates from the waste were consistent with nickel to sulphur ratios in the solids. This relationship provided a tool to assess the risk of metal leaching in wastes using nickel and sulphide assays. Nickel release and mobilization was found to occur for both oxidizing leach tests and under water tests even when pH values exceeded 7.0. Geochemical model calculations showed that iron oxyhydroxide solids can scavenge nickel from leachate and that the nickel inventory can be released from solids at relatively lower, but neutral pH values.

Jan 1, 2000

By Jeff Poe

When a takeup weight is offset to the side of a conveyor, a wire rope is commonly routed from the takeup weight through a series of sheaves to the takeup carriage. The friction developed from a series of wire rope sheaves can effect the actual belt tension at the make up carriage. Through real-mime testing the actual tension on a makeup carriage was recorded with data acquisition using an internally strain-gauged turnbuckle. The wire rope used to transfer the makeup weight to the makeup carriage was routed through a series of lubricated bronzed bushed sheaves. The tension on the makeup carriage was found to be as much as 26% higher than the weight of the makeup due to the friction in the sheaves. A detailed discussion of the testing and results will be made.

Jan 1, 2000

By C. Orf. Chukabarah

Erratic behavior in convergency during iterative numerical-method evaluation of mine ventilation fan characteristic curves is one of the common problems encountered in mine ventilation network analysis. Five different sets of mine fan data points, that had resulted in unsatisfactory fan characteristic curves, were re-analyzed in the present study, using an embedded mine network optimization computer program. Current results revealed that all five fan data sets not only can be satisfactorily fitted as Yang (1992) did with MFIRE subprogram, but can further be optimized with unique solutions as implemented in the present study. It was concluded, inter alia, that the improved MFIRE-based mine fan curve-fitting computer subprogram (SPLINE) produces satisfactorily similar fan curves as SPSS-based curve-fitting algorithms, including when the latter method uses either standardized or unstandardized fan curve data sets.

Jan 1, 1993

By Qun Wang, Elena A. Alonso, Janusz S. Laskowski

Primary normal long-chain amines are insoluble in saturated brine. Their colloidal solubility (dispersion) in concentrated electrolyte solutions is strongly affected by the presence of surfactants (frothers). This paper shows that a better usage of alcohol type surfactants, which are commonly used in potash ore flotation as frothers, can significantly improve the flotation of both coarse and fine sylvite particles. A new process of potash ore flotation is developed, which includes premixing an effective frother with an aqueous solution of amine or emulsion of extender oil containing amine. With such a combination of flotation reagents, KC1 particles up to 5 mm in size float very well in the short flotation column, and particles up to 2 mm float in a mechanical cell; when used to treat fine fraction-containing sample, this method may as well provide an improved concentrate grade.

Jan 1, 1995

By David C. McLean, Peter Penner, Martin de G. Salter

The Rogers Pass Project for C.P. Rail includes a 14.7 km tunnel and an 8.5m diameter concrete lined ventilation shaft to a depth of about 335m. The shaft collar is in bouldered water bearing glacial till to a depth of about 95m. Initial excavation in the overburden was with the aid of dewatering wells. When ground support problems arose the excavation was completed by a two stage freeze programme. Freeze holes were drilled from the shaft bottom. This most unusual method was successful in overcoming the difficulties safely and efficiently. The remainder of the shaft was sunk and lined conventionally. Finally, a central dividing wall was poured by jump forming from the bottom up. The wall was completed to a high standard at up to about 20 vertical metres per day.

Jan 1, 1989

By Nora M. Hutt, Kevin A. Morin

One technique for controlling ongoing acidic drainage is to relocate and submerge net-acid-generating waste rock in a lake or water-retaining impoundment. This can lead to the overall improvement of water quality and the reduction In short-term environmental liabilities. A case study of this technique is the Eskay Creek Mine in northern British Columbia. Some findings of the study are: (1) the addition of lime to each truckload of rock, based on its rinse pH, neutralized the accumulated acidity and suppressed the accumulated-metal release, (2) only 10-20% of the dump's neutralization potential had been consumed when acidic drainage appeared, (3) water chemistry in the watershed recovered roughly three years after relocation, and (4) environmental liability was reduced due to the cessation of on-land acidic drainage with no degradation of lake chemistry.

Jan 1, 2000

By T. M. Campoy, J. R. Jones

When extending the life of an existing mine in Appalachia, it is common to acquire the adjacent reserves and extend the existing mine into it. The existing mine is often renovated to accommodate the new conditions. The existing mining system and the track and belt haulage systems may he modified while the new property is integrated into the old one. All of these changes create new constraints for the mine ventilation system (MVS) that require proper planning and control procedures. This paper presents a study that was carried out for the ventilation system of a newly expanded underground coal mine in the Appalachian region. The process of correcting the ventilation system of the existing mine is discussed. That is followed by a discussion of some of the stages of controlling the expanded system. Numerical data for these steps are also presented.

Jan 1, 1994

By W. Petruk, D. B. Sikka

Lithium-bearing lepidolites from three deposits in the province of Goias, Brazil, were investigated to determine whether there is a correlution between the lithium content of the mineral and the color of lepidolite and associated tourmaline. Such a correlation can be a useful guide to field geologists for outlining high-grade lithium ore zones. It was found that mauve-pink lepidolite associated with pink tour-maline, and brownish lepidolite associated with black tourmaline have high lithium contents, but that the color of lepidolite is not due to lithium. The pink color of lepidolite and tourmaline is likely due to Mn3+, and the brownish tint of lepidolite and black color of tourmaline to Fe3+. Lepidolites appear to be lithium- rich when the lepidolite and associated tourmaline contain relatively high amounts of Mn3+ and/or Fe3+.

Jan 1, 1988

By R. R. Tatiya

The algorithms to model three stoping methods - sublevel, down- the-hole (DTH) and cut and fill stoping have been developed. These algorithms are capable of designing and performing economic analysis for one or more number of stopes in a continuous orebody. The design and economic analysis of each individual stope are first obtained. This is followed by the composite stope design layout and overall economics of the stopes under study. This paper describes only the stope design aspects of these models. The programs have been written using Fortran 77 with Tektronix graphical aids available at Imperial College Computer Centre (ICCC) London and are based on the basic data obtained from Khetri Copper Complex (KCC) and Rajpura Dariba (a zinc mine) in India. Minor modifications, however, may be necessary in some routines when used on other systems and for other mines.

Jan 1, 1989

By R. Poulin, R. C. Pakalnis

Approximately 51 % of all ore production in Canadian underground metal mines is derived directly from open-stope operations. This method requires that large excavations remain open until the ore is extracted with a minimum acceptable level of dilution. A survey of underground mines in 1988 reported that a major factor in their closure was uncontrolled dilution. It has been reported that 40% of openstope operations were experiencing dilution in excess of 20%. This level of dilution has significant implications on the economic viability of a project, especially when one considers that a rate of return on a positive project is generally between 10% and 20%. This paper reports on the various definitions of dilution, on the methods of stope design that are presently used with the objective of reducing dilution and on a recently available survey technique that enables dilution to be quantified.

Jan 1, 1996

By John E. Urbanic, William D. Faulkner, Robert W. Ruckel

Guidelines are presented for the selection, handling and regeneration of activated carbon used in gold recovery operations. The guidelines are based on Calgon Carbon Corporation's own investigations and experience gained in working with gold mine operators all over the world. Gold adsorption rate and adsorption capacity are shown to be independent variables thereby requiring testing of both properties when selecting activated carbon. Means of measuring these properties are provided. Historical activity tests on activated carbon are shown to be minimally useful in selecting carbon for gold recovery. Proper thermal regeneration techniques to maximize recovery of adsorption rate without weakening the carbon structure are suggested. Simple positive means of measuring efficiency of regeneration are presented. The subject of hardness measurement as a predictor of "in process" abrasion is discussed. The cost/benefit issue of carbon activity level is addressed.

Jan 1, 1986

By Qing Wang

A longterm overburden removal plan can be realistic and optimum only when the cost and capacity profiles off the equipment assigned to the operation are taken into consideration. Therefore, the planning should involve the proper assignment of equipment capacity by insuring a timely investment and a timely replacement policy throughout the mine life. A dynamic solution algorithm has been developed, by which all possible truck fleet alternatives are evaluated for each year off the operation. Cumulative cost off the operation is carried throughout the analysis. The optimum solution is obtained by selecting the minimum cumulative cost at the last year and tracing backward the best fleet alternative for each year. The solution provides: 1. the optimum amount of overburden to be removed each year; 2. the best fleet to be assigned to the job; and 3. the best equipment replacement policy.

Jan 1, 1989

By K. L. Whitehead, R. A. Jankowski, N. I. Jayaraman

Most continuous miner sections utilizing flooded-bed scrubbers also use blowing face ventilation. Blowing ventilation, however, interferes with dust capture and minimizes scrubber effectiveness. To enhance the efficiency of the scrubber system and reduce dust concentrations, the Bureau of Mines tested various combinations of operating parameters. Experiments for system efficiency took place in a full- scale model mine at 3.05 m roof height. In general, higher values for scrubber and face airflows resulted in lower dust concentrations. In addition, optimum dust controls would include a face ventilation to scrubber airflow ratio of one. When the airflow ratio was either less than or greater than one, the dust levels in the return and at the operator locations increased. No single dust control technique was the most effective one at all locations due to mutual interaction among techniques.

Jan 1, 1992

By G. F. Friel, J. C. Edwards, C. C. Hwang

In the implementation of a mine fire alarm and location strategy, the Interpretation of the fire signature Is Important. Smoke and CO are the two dominant fire signatures, and many mine fire detection systems utilize sensors which respond to smoke or CO through a diffusion mode or a mechanical pump mode. The fire signature may be modified during its transport along airways and at crosscuts. The modification occurs through dilution of the contaminants. In this Investigation, computer codes were employed to compute the effects of contaminant dilution on the contaminant signature when a straight flow passage has one dead-end crosscut. The model predicted the airflow within always and the entrainment of contaminants into the crosscut from the airway. One application of the model is to determine the most suitable location for CO detectors for early mine fire detection.

Jan 1, 1995

By X. Wu, M. G. Karfakis, K. Y. Haramy, B. T. Brady

A quantitative evaluation of damage caused by ground motions associated with strong roof caving is presented. The strong roofs are modeled as either cantilevering or bridging beams over continuous elastic foundations that are subject to an exponentially distributed vertical stress. Major factors influencing roof caveability and strain-energy buildup are identified and investigated. A methodology for the evaluation of strain-energy accumulation caused by, an overhanging roof is presented. The potential for mine tremors is determined in terms of the local Richter magnitude (ML), which depends on the seismic energy transformed from the stored strain energy that is released when the roof fails. A particle-velocity model is applied to estimate the damage area associated with roof collapse. A case study from a Utah coal mine shows that estimations of bump severity and the damage area agree well with field observations.

Jan 1, 1997

By E. J. Donovan, O&apos

The use of Dynamic Analysis techniques in the design of conveyor systems is extremely limited. The most frequent use of the technique is in large and expensive systems where the emphasis is on insurance against failure caused by catastrophic tension waves. This paper sets out to illustrate a much wider range of applications where dynamic analysis has been successfully employed. The examples chosen deal with identification and correction of dynamic low tension problems, the variability in take-up movement as other system parameters change, the requirement for proper tuning of starting controls and finally the absolute necessity for a complete understanding of the entire system when specifying brakes for critical applications. The intent of the paper is to get designers to view a conveyor as a system of interacting flexible components rather than as a single rigid body.

Jan 1, 1993

By F. M. Doyle, Jun Li, Milton E. Wadsworth, E. Peters

The Raman spectroscopic technique was used to study electrochernically oxidized pyrite in-situ. It was found that Raman-active sulfur oxidation products could be detected after a proper potential was applied to the pyrite electrode for a threshold period of time. There existed a minimum potential below which sulfur could not be observed. However, when the applied potential exceeded a certain limit, the intensity of the sulfur spectra decreased. The minimum potential at which sulfur could be observed changed with solution pH. For both acid (pH 2.7) and weak alkaline (pH 9.2) solutions, the minimum potential was 0.8 V/SCE, whereas for neutral (pH 6.5) solutions the value was 0.4 V/SCE. In strong alkaline solutions (pH 12.5) surface sulfur oxidation products could not be detected at any potential.

Jan 1, 1993

By R. M. Carland, F. F. Aplan

The ion-exchange capabilities of natural zeolites from the western United States, representing the species chabazite, clinoptilolite, erionite and mordenite, have been studied because of their potential use in environmental remediation and in hydrometallurgical processes. These raw zeolite samples were found to contain Na+, K+, Ca+2 and Mg+2 as exchangeable cations, and all of these, with the exception of Na+, were found to seriously interfere with the exchange of Cu+2 from solution. Placing these zeolites in the Na+ form was found to increase their cation-exchange capacity, often massively. In addition, the elution of Cu+2 from the Na+ pre-exchanged zeolite is greatly facilitated when the deleterious K+, Ca+2 and Mg+2 have been largely expelled. The relative influence of these deleterious ions on the uptake and elution of Cu+2 was determined.

Jan 1, 1996

By K. Hanumantha Rao, P. K. Sharma

A pure strain of Paenibacillus polymyxa and mineral- adapted strains are used to bring about surface chemical changes on pyrite and chalcopyrite and, thus, theirflotation. Paenibacillus polymyxa was adapted by repeated subculturing in the presence of pyrite and chalcopyrite. The surface chemical changes of bacteria due to adaptation and of minerals after their interaction with bacterial cultures are evaluated by electrokinetic and infrared spectroscopy and are discussed with reference to their flotation responses. Interaction of bacterial cells, bacterial metabolites and whole bacterial cultures affected the Hallirnondflotation behavior of the sulfide minerals. The Xanthate flotation results show that pyrite, but not chalcopyrite, is depressed when the tests are carried out after interaction with chalcopyrite-adapted Paenibacillus polymyxa. This investigation demonstrated that the surface chemical properties of bacteria can be manipulated successfully to achieve the desired effects in the flotation process.

Jan 1, 2000