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By S. P. Banerjee

Injection of inert gases to combat mine fires has been practiced in various parts of the world for a long time. Of late, nitrogen has become the preferred inert gas for control of mine fires and safe salvage of longwall equipment as compared to carbon dioxide or fuel gases produced from burning of fuel. In India, carbon dioxide has been used for fire fighting in a number of mines during the 1960s and 1970s. More recently inert gas produced from burning of fuel oil in surface plants has been used in controlling the atmosphere in fire areas in two mines. In yet other cases, liquid nitrogen has either been poured directly into fire areas in liquid form or injected in gaseous form to keep the fire in check. Nitrogen produced in liquid form in an oxygen plant is more costly than nitrogen produced from PSA (pressure swing adsorption) based plants. A PSA-based plant has been installed in one of the Indian mines in 1986 and more are in the offing. This paper reviews the application of various inert gases in Indian mines and discusses the likely trend of inert gas application in Indian mines in the future.

Jan 1, 1987

By M. H. Al-Dabbagh

In this paper, the authors outline the deficiencies of PERT/CPM as a method for scheduling complex projects such as mine development. In particular, PERT/CPM networks cannot accommodate logical nodes (events) or stochastic branches (activities). The Graphical Evaluation and Review Technique (GERT), developed by Pritsker and. co-workers, is introduced as an alternative to PERT/CPM that overcomes many of the deficiencies of the latter and enables a more realistic analysis of complex projects that are subject to significant uncertainties. A brief overview of GERT network structures and network analysis is given and a PC implementation of the method is described. The technique is illustrated by application to the development of an open-pit gold mine in Saudi Arabia.

Jan 1, 2002

By A. D. Davis, C. J. Webb, T. V. Durkin

This project took a watershed approach in the evaluation of water-quality impacts from past mining activities and current restoration projects in the Bear Butte Creek basin, a small and well-defined drainage in a heavily mined area of the northern Black Hills. The basin contains numerous inactive and abandoned mines, as well as a heap-leach surface gold mine. Bear Butte Creek normally loses all of its discharge to sinkholes in the Madison Limestone aquifer. Thus, it can affect the water quality of this regionally important water resource. Water-quality data were analyzed, stream surveys were conducted and two abandoned-mine restoration projects were monitored to evaluate the effectiveness of the watershed approach and to identify practical remediation techniques that could be applied to other watersheds. A geographic information system (GIS) was developed to organize information on stream quality, abandoned mine locations, and other geologic and hydrologic data. The watershed approach toward assessing and reclaiming abandoned mines appears to be effective when compared to a point-source approach that might improve water quality at specific sites but not result in significant overall improvement to the watershed because of adjacent sources.

Jan 1, 2000

By Jim M. Johnson

INTRODUCTION The facility water balance and maintenance of sufficient excess storage volume in the solution control system are often amongst the most critical facets of design and operation of heap leach facilities in cold, snowy climates. The purpose of this paper is to summarize and discuss climatic and operational factors which have a significant impact on heap leach water balance evaluations in high snowfall climates. Example water balance simulations are presented for proposed heap leach projects located in areas subject to high snowfall in the northwestern United States. The climatic data input to these simulations represent both net evaporative and net precipitation climates. FACTORS AFFECTING WATER BALANCE EVALUATIONS The combined effects of seasonal operations, re1atively low evaporative losses, and potentially large inflows to the solution control system from snowpack and spring storms require an enhanced awareness of the factors which impact facility water balance. Unlike operations at mines in more arid climates, seasonal excess water rather than a shortage of make-up water is the rule. A thorough understanding of a number of factors, including regulatory constraints, climatic influences, and impact of operating philosophy and techniques, is critical to successful development of an incident-free heap leach operation under high snowfall climatic conditions. A process water circuit schematic for a typical heap leach operation is shown on Figure 1.

Jan 1, 1988

By J. F. Cuderman

In situ experiments at the Department of Energy's Nevada Test Site (NTS) have extended the technology of propellant-based fracturing to include liquid- filled, uncased boreholes. Previous work had developed the technology for liquid-free, uncased wellbores. Test results show that fracturing behavior is considerably more complex in liquid- filled boreholes than in the liquid-free case. Compared to liquid-free boreholes, liquid-filled boreholes have faster pressure risetimes and lower peak pressures, large hydraulic-type fractures propagating several meters beyond the end of the test zone, numerous oscillations in the pressure history, and variable types of fracturing within a single test region. Multiple fracturing is initiated in the wellbore of a fluid-filled borehole when the proper propellant mixture is used but, unlike fluid-free wellbores where up to eight fractures propagate, only one to three hydraulic- and/or shear-type fractures propagate. Hydrodynamic effects involving liquid compression during borehole pressurization appear to be responsible for the differing phenomena observed in fluid- filled boreholes.

Jan 1, 1986

By G. Newman, C. D. Sellars, E. A. Portfors

Power for mine operation in remote locations is usually provided by diesel generators. For gold mines where processing is normally desirable on-site, power requirements can be significant and the operating cost for diesel generation then becomes an important factor in mine feasibility. If a suitable site is available, a small hydroelectric power facility near the minesite can provide a significant portion of the mine power requirements. The hydrological, engineering and economic factors involved in small hydroelectric power development are described in this paper. Capital costs are minimized by run-of-river hydro development which does not require a dam and reservoir and has less environmental impact. During periods of low flow, diesel generators are used to make up the power demand. The hydrologic analysis required to determine unit energy costs is described and technical requirements for linking the hydroelectric power facility with diesel generation are outlined. Case studies are presented demonstrating the economic advantages of a small hydro installation. One case study is for a proposed gold mine in British Columbia and the second is a large operating gold mine overseas, for which the hydroelectric power scheme is presently under construction .

Jan 1, 1987

The development of economical and effective treatment processes for solid and aqueous waste is a critical issue facing the mining industry today. Cyanide, nitrates and acid rock drainage are environmentally sensitive effluents that require treatment or containment for acceptable disposal. In situ biotreatment processes are an emerging technology (Thayer) for cyanide oxidation, denitrification, sulfide mineral alteration and metal re- mineralization. Biological cyanide oxidation is competitive with chemical treatment processes (peroxide, alkaline chlorination) for process solutions, spent ore and tailings detoxification. Microbial denitrification treats mine waste contaminated with nitrates from blasting, processing or nitrification of the host rock. Bio-alteration of sulfide minerals and metal re-mineralization may present the most cost-effective and environmentally acceptable method of dealing with sulfide tailings and leachate solutions. Field test programs for cyanide bio-degradation and denitrification of spent ore and process solutions were designed and run at two mines. Although the treatment bacteria and the application processes are similar, each waste presented site-specific problems for adapting the biotreatment processes. Some of the site problems include climate, ore geochemistxy, field bacteria production, waste microbiology and application engineering. This paper compares treatment design and results for cyanide oxidation and denitrification in heap detox treatments.

Jan 1, 1992

By W. E. Foreman, A. Hayatdavoudi, A. Ghalambor

The objective of this investigation was to determine the sensitivity of three selected input parameters in the operational control of continuous bottom fed thickeners used for the treatment of coal refuse slurries. The three variable parameters were "Feed Flow Rate," "Feed pH," and "Feed Solids Concentration." These three input parameters were studied under three cationic-anionic polymeric conditions. For each polymeric condition, two mathematical models were developed, one for overflow response and the other for underflow response. The combination polymers produced the best quality of overflow and underflow. For this polymeric condition, change in the feed solids concentration was the most sensitive factor in the maintenance of the overflow quality, and the feed pH was the most sensitive factor for the maintenance of underflow quality. The mathematical models generated a set of plots that would allow an operator to control and/or adjust any of the three variables to achieve optimum conditions.

Jan 1, 1991

By Bruce M. Davis

The variogram is the function used to express the intercorrelation of a regionalized variable. It is used to quantify, for example, the natural variability of mineralization and in that sense may be thought of a average disimilarity between metal quantity at two points inside a deposit.2 As David2 explains, appropriate mathematical functions of distance and direction are used to characterize variograms, a process that he says is analogous to selecting a normal or lognormal model for an observed distribution. Methods for choosing a model for the underlying variogram of a random function based on the sample data appear in the literature.3,8 A crossvalidation procedure is available to check the validity of the model.3 However, statistical validation of the choice of the model through the mechanism of hypothesis testing is not presently available. In the section to follow, notation and background material is presented upon which a large sample test procedure will be constructed. The stationarity assumptions presented refer to covariance stationarity. A test procedure is then proposed, and an example is given for the case of the one dimensional random process.

Jan 1, 1979

By R. L. Jones, D. D. Runnels, D. P. Dupon, D. J. Cline

To establish meaningful remediation goals and monitoring programs in areas disturbed by mining and associated industries, it is desirable to determine the natural concentrations of metals that existed in these areas prior to being disturbed. In mineralized areas, multiple natural populations of metals and associated components may be present. This paper describes a method for characterizing the natural background chemistry by means of probability distribution dia¬grams. The method can be applied to water, soil and other natural materials. In a study of a complicated hydrogeologic system at the Kennecott Utah Copper North and South Operational Areas near Salt Lake City, UT, probability distribution diagrams were used to differentiate between natural background waters and waters impacted by human activities. The probability distribution diagrams allowed a component-by-¬component interpretation of the chemistry of ground¬water and surface water over a large geographic area. Natural chemical background populations and anthro¬pogenic effects were identified Although the method is illustrated for mining-related sites, the same approach can also be used for other natural and anthropogeni¬cally impacted sites.

Jan 1, 1999

By B. K. Baird, P. C. Satchwell

The application of cutoffs during and after pit optimization is examined for a lower-grade multimetallic copper deposit. Pit optimization requires calculation of the net revenue associated with each mining block. The calculation incorporates parameters such as metal prices, grades and expected recoveries, mining and processing costs, smelting and refining charges, and penalty element and royalty charges. Sensitivity analysis during pit optimization reveals which parameters have significant effects on the total contained resource tonnage and total contained nondiscounted revenue in the optimized pit. The cumulative effects of changing several of the more-significant parameters are investigated The application of a copper cutoff grade to a block inside the optimized pit could result in the less-than-optimal extraction of the resource. A block with a copper grade below the applied cutoff could be economic due to the presence of other metals. Conversely, a higher-copper-grade block may be subeconomic. Also discussed are the merits of applying a copper-grade cutoff, an "equivalent-grade" cutoff and a dollar-per-ton cutoff to blocks inside the optimum nit.

Jan 1, 2002

By K. G. Sutterer, P. T. Wang, R. Sweigard

One possible alternative for the disposal of flue gas desulfurization (FGD) by-products is to use it as backfilling support material in highwall mine adits. The finite element method was used to analyze the variation in stresses and displacements within and around a highwall adit backfilled with FGD materials. The engineering properties of the rock material and the optimum mix of the FGD materials were obtained from laboratory tests. Finite element analyses show that, for the case in question, the roof displacement would decrease about 48% and the peak stress could be decreased by about 58%. The study indicates that fairly weak FGD materials can eventually lead to the stability of backfilled highwall adits.

Jan 1, 1998

A new separator, known as the HydroFloat cell, was developed to overcome the limitations of traditional flotation cells in recovering coarse particles. The HydroFloat cell separates particles based on differences in mass after the selective attachment of air bubbles to the hydrophobic component of the feed stream. Proof-of-concept testing, utilizing phosphate matrix, heavy mineral sands and anthracite slag, indicated that significant improvements in separation efficiency can be achieved using this air-assisted teeter-bed system. Based on the encouraging laboratory results, a pilot-scale HydroFloat cell was fabricated and installed at a central Florida phosphate plant. Test data collected using the pilot-scale unit suggest that the BPL recovery of the +35-mesh plant feed can be increased by snore than 40% through the application of this new technology. This improvement is particularly beneficial due to the very high grade (-73% BPL) of the +16-mesh particles in the HydroFloat concentrate. This article describes the theoretical basis for the development of the HydroFloat cell and provides an overview of recent laboratory and pilot-scale test results.

Jan 1, 2002

By J. Scott McDougall, J. Herman P. Eng. Vanderlaag

An underground mine fire can seriously threaten the lives of all personnel in the mine. This fact makes fire emergency planning a high priority in the mining industry. The optimum warning alarm must be fast and able to reach all miners, regardless of their location or work activity. Current means of fire warning are varied, and include such methods as stench, telephones, and word-of-mouth (messengers). Unfortunately, none of these methods are entirely satisfactory. A novel fire warning alarm which enables instantaneous warning of all underground personnel, the Canary Nine Messenger System, has been developed by VLF Magnetic Systems Inc. in conjunction with Noranda Technology Centre and the U.S. Department of the Interior - Bureau of Nines. The warning is sent by an electromagnetic signal which penetrates through mine rock to receivers housed in the battery packs which also power each miner's cap lamp. A loud buzzer in the integrated battery/receiver unit and the flashing of the cap lamp alerts miners to incoming messages. Testing of prototype equipment has demonstrated that the transmitted signal is capable of penetrating through over a mile of mine rock and activating the receiver. This report describes the theoretical basis for through-the-rock ultra-low frequency electromagnetic transmission, and the design of recently available transmitter and receivers.

Jan 1, 1995

By W. M. Schafer, C. F. Luckay, D. A. King

Monitoring devices have been installed at several mine sites to assess the potential for the development of acid rock drainage (ARD) in waste rock, spent ore and tailings material. In addition, instrumentation has been designed for monitoring changes in water quality in pit lakes. These devices monitor temperature, oxygen, water movement and water chemistry in the waste rock pile. This information can be used to evaluate the current and future ARD risks and the effectiveness of caps and covers. The information can also be used in the design of other reclamation strategies that limit ARD development. The instrumentation includes nested thermistors and oxygen sensing ports, neutron access tubes, heat dissipation units (HDUs) and lysimeters. Many of the monitoring devices can be linked to a data logger and telemetry systems, enabling monitoring data to be downloaded from the office.

Jan 1, 1999

By R. Venugopal, T. C. Rao, M. Vanangamudi

Introduction The kinetic approach, to understand a process in detail, has been extensively used in the unit operations of many engineering systems. In green pelletization, the kinetic studies have been mainly oriented towards quantifying the growth mechanism (Kapur and Fuerstenau, 1964; Sastry and Fuerstenau, 1977; Capes and Danckwerts, 1965; Kapur and Fuerstenau, 1966; Kapur, 1972) and in a few cases, relating the rate of growth with added liquid content (Kapur and Fuerstenau, 1964; Newitt and Conway-Jones, 1958). Studies on the kinetics of green pelletization, in terms of the order of the kinetics are virtually non-existent. Sastry and Fuerstenau (1970) classified the agglomeration process into "free in-space" (dilute particle system) and "restricted-in¬space" (highly dispersed particle system) and noted that the former is a second-order process while the latter corresponds to a pseudo first-order rate process. The present paper attempts to describe the kinetics of green pelletization, in terms of order of the kinetics, using pyritiferrous shale as the material system. Experimental Pelletization experiments were carried out using -100 mesh pyritiferrous shale, in a laboratory disc pelletizer, at four intervals of pelletization time (15, 20, 25 and 30 min). The green pellets obtained were size analyzed. The size distribution of pellets has generally been represented by a single parameter such as the mean granule diameter, ratio of maximum and minimum pellet diameter, etc. In the present study, the d50 (50% passing size) of pellets has been considered to represent the size distribution of pellet. Kinetic equations The process of size enlargement is considered analogous to chemical reaction and a general kinetic equation of nth order for growth of pellets is given as

Jan 1, 1990

By D. Malhotra, R. M. Hoover

The effect of a surfactant, designated Syntex, on the wetting and spreading of hydrocarbon oil on molybdenite surfaces (faces) has been investigated experimentally through measurements of zeta potentials and factorially designed flotation tests. These studies indicate that Syntex has a positive effect in increasing molybdenite recovery in the rougher flotation circuit at the Climax mill. The analysis of experimental data using DLVO theory shows that the controlling factor in determining the magnitude of the repulsive energy barrier preventing oil from wetting and spreading on the molybdenite faces is the MoS2 zeta potential and the vapor oil droplet size. The role of Syntex in this case seems to be related to the decrease and stabilization of MoS2 zeta potential by Syntex adsorption and also to the emulsifying action of Syntex on vapor oil to provide a more favorable oil particle size.

Jan 1, 1976

By Neil B. Prenn

Drill-hole contamination has been a problem for many years. Contamination of rotary drilling has been well documented. More recently contamination in wet reverse circulation drilling has been noted by Echo Bay and others at the 1991 AIME annual meeting. Mine Development Associates (MDA) has worked on a number of projects at which contamination of drill-hole samples has occurred. Properties are commonly acquired with drilling accomplished by other companies and at times the only records of the drilling program are the drill-hole logs and assays themselves. Identification of contaminated zones is sometimes difficult to determine. Most geologists and engineers in the industry are aware of the magnitude of the problem, as contamination is a relatively common problem with wet reverse circulation drilling. MDA has developed a computer program to help determine if contamination has occurred when using reverse circulation drilling, based on cumulative distribution curves and by a process we call decay analysis. Most deposits are not homogeneous throughout the deposit, but exhibit a characteristic drop-off or decay of assay values around higher-grade drill-hole intercepts. Using graphs of this characteristic decay and cumulative frequency distribution, we can use the program to help determine contamination in several ways. This paper will discuss the use of decay analysis at three gold deposits where contamination is known to have occurred. In one of the deposits decay analysis was used, successfully to determine if contamination had occurred, while in the other two the decay analysis was used to verify our decay analysis procedure.

Jan 1, 1992

By Fathi Habashi

THE CHOICE of a precipitant for a certain metal ion depends, beside the economic factor. on the following factors: 1) The precipitant should be specific as far as possible so that pure precipitates can be obtained

Jan 1, 1970

By Manuel Bernales, Aldo Leon, Alexandra Carlier, Bern Klein, Andre Xavier

Mining companies and governments at both the local and national levels recognize that Participatory Environmental Monitoring and Surveillance Committees (PEMSC) are necessary mechanisms for meaningful engagement at the community level. In many cases, PEMSCs are established as volunteer initiatives by mining companies or by the mining communities themselves. In Peru however, they can also be recommended by the government as way to address social conflict. Most PEMSCs are launched while a mine is in operation and have the objective of monitoring both water quality and quantity. Many established committees are currently evolving and adopting a more comprehensive approach, as well as expanding their initial scope from a river or micro-basin focus and watchdog agenda, to a broader regional integrated resources management view. This paper examines the origins of Participatory Environmental Monitoring and Surveillance Committees in Peru. It also discusses the typology of these committees, and the scope of their work. Furthermore, it looks at the challenges faced by these committees, as well as existing opportunities for mining companies, governments, and civil society. Finally, this study presents a governance model that could contribute to the long-term existence of these committees. This discussion is further informed by the results of a national workshop that took place in October 2016 in Peru, in which over 200 representatives from 22 monitoring committees, government and mining companies participated.

Jan 1, 2017