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By Robert F. Hauck

This chapter discusses a new technology for computer control in open-pit mine operations: the real time automatic dispatching of manually driven trucks to shovels. The monitoring of truck activity is accomplished by detection of local radio signals. Computer-operated directives are communicated to drivers by remote controlled digital display units inside the truck cab. The production objective is to maximize tonnage in a cost effective manner. The problem is formulated in the appendix and the solution method is briefly described. Side conditions such as maintaining delivered ore grade aims, balancing waste to ore volumes to keep within stripping ratio tolerances, and meeting production rate requirements temporarily established for certain shovels are also discussed. Experience with a developed event- to-event simulator applied to analyses of several North American mining operations using this technique is summarized. Complete systems employing this technology are now under- going installation at mine sites in Canada and the United States.

Jan 1, 1979

By L. E. Krys, K. D. Harrison, S. M. Nordwick, C. G. Anderson

Since 1984, nitrogen-species catalyzed pressure leaching has been utilized at the Sunshine Mining and Refining Company for the recovery of precious metals from a refractory sulfide concentrate, The process operates without the use of cyanide. The plant is now the only industrial-scale commercial application of this technology. Since the inception of the process, changes have been implemented to improve efficiencies and throughputs. Two of these changes, the replacement of nitric acid by sodium nitrite and a concentrate regrind, have recently been implemented. This paper will discuss the outcomes of these recently patented plant-process changes. In particular, a comparison between the previously used method and the new leach method is made. Also discussed is the potential applicability of the process to other materials. A companion publication (Anderson, Harrison and Keys, 1996) indicates possible mechanisms responsible for the success of these process changes.

Jan 1, 1997

By G. T. Adel, W. Z. Choi

A model describing size reduction and mineral liberation during grinding has been extended to include multiple classes of composite particles. The majority of the model parameters have been directly determined using computerized image processing equipment to analyze the products from batch grinding tests. A coarse-grained sphalerite ore from Tennessee, representing a nearly ideal binary mixture of sphulerite and dolomite, has been used to experimentally validate the model for the case of dry batch grinding. In all cases, excellent agreement has been observed between the model predictions and the experimental results.

Jan 1, 1988

By J. M. Barker

Formation of commodity agreements depends mainly on the economic instability and associated mitigation measures inherent in the economic conflict between more developed and less developed nations. Five types of possible agreements exist: futures market, buffer stock, restrictive agreement, multilateral contract, and compensatory finance. Lack of market separation between sulfur consumers and producers coupled with large world production and highly concentrated export production in theory suggest a restrictive agreement as most likely. In practice, stockpiling of sulfur, an informal buffer stock, as done in Canada and perhaps the Middle East, has been the main sulfur price-supporting mechanism in the past two decades. No commodity agreements involving sulfur now exist except for multilateral contracts. Sulfur agreements apparently have existed rarely, if at all, in the past. Law (1975) refers to sulfur as one of a group of commodities where "there have been additional control efforts of various types." Clearly, sulfur was a candidate, at least conceptually in the past, for some form of commodity agreement. The following discussion centers on the world sulfur market from 1976 to 1985 in this context.

Jan 1, 1987

By Krzysztof Filek, Anindya Sinha, Bernard Nowak

Taking into account the possibilities of condensation of water vapour contained in air during its flow through a series of spot coolers as well as formation of eventual fog, a mathematical model of dynamic temperature, specific humidity and degree of fogging of cooled air in underground mining galleries with direct ventilation is developed. In the gallery, there situated various heat and moisture sources both of distributive and of concentrated types. The model is represented by three partial differential equations of first order. The cases of cooling with full as well as with partial air stream flowing through the gallery are distinguished. Owing to the fact that in practical designing, more important is the knowledge of the variation process of temperature, specific humidity and fogging of cooled mine air at steady state conditions, the model is modified to a set of three nonlinear ordinary differential equations. Based on the presented algorithm, the obtained set of ordinary differential equations is numerically solved which enables to: • specify the distribution of temperature, specific humidity, relative humidity and degree of fogging of cooled air in mining galleries; • determine the cooling powers of air coolers for their known locations; • indicate the locations of the coolers of known cooling powers. Exemplary calculations of temperature and relative humidity of cooled air are presented graphically in a number of diagrams.

Jan 1, 1997

By J. Pang, S. Chander

The results of an investigation to characterize the chalcopyrite/solution interface are presented. Several techniques were used, including galvanostatic and steady-state polarization, cyclic voltammetry and impedance spectroscopy. The results show that the dissolution of chalcopyrite was incongruent. Initially, at low potentials (< 0.12 V), iron species were released that led to the growth of an iron-deficient sulfide (IDS) layer (referred to as the "reacted layer" in this paper). Depending on the solution&apos;s composition, the dissolved iron might reprecipitate as a hydroxide layer. In the potential range of 0.12 V < E < 0.23 V, the IDS layer was passivating. In comparison, development of a passivating IDS layer under galvanostatic conditions led to a jump in potential to 0.48 V. The IDS layer began to dissolve at potentials greater than 0.24 V. The dissolved species precipitated to form a product layer in alkaline solutions. Continued oxidation involved diffusion of species through the reacted and product layers. At higher potentials (> 0.48 V), further oxidation led to the dissolution of the copper and sulfur species, with a resultant breakdown of the IDS layer. The changes in surface-coating properties, resulting from various electrochemical treatments, are discussed.

Jan 1, 1993

By Richard Jr. Ray, Richard Druesedow

The Virginia Operations of Consolidation Coal Co. include a diversity of mine fan configurations which have been tested to quantify pressure losses through the inlet ductwork. Airflow and pressure measurements were taken at four shaft sites to calculate losses for the 90-degree bend at the top of the shaft and the self-closing dampers or closing doors located between the shaft and fan. Velocity contours were then developed from the test data to determine flow patterns in each fan system component. In addition, yaw and pitch angles of airflow through the fan annulus were measured to evaluate turbulence levels created by various inlet ductwork designs. The test results indicate that proper design of the shaft collar and ductwork arrangement for main mine fans can substantially reduce system pressure losses and air turbulence. BY minimizing the pressure drop experienced on the surface, these design improvements enable the bulk of the total pressure developed by the fan(s) to be utilized in the mine.

Jan 1, 1995

By F. M. Doyle, S. Duyvesteyn, K. Sreenivasarao

Toxic metals entering surface or ground water from sources such as metal finishing shop spills and abandoned mines can pose a significant threat to public health and the environment. Ion flotation and similar foam separation techniques show great promise for treating dilute, metal-contaminated solutions, and could also be used to treat effluents from many minerals and metallurgical processing operations prior to discharge. In ion flotation, an appropriate collector is added to the solution to form hydrophobic complexes with the metal ions. These metal-bearing species are then removed by flotation, usually with trace addition of a frother to stabilize the foam. In an effort to better understand the underlying scientific and engineering principles that determine the performance of ion flotation, the removal of Cu(II), Pb(II), Cd(II), Cr(II) and Cr(VI) has been studied using laboratory scale flotation columns in batch mode. The effects of the superficial air velocity, solution and froth height, nature of the collector, collector: metal-ion ratio, ionic strength and several frothers at low concentrations on the flotation kinetics are reported. Finally, results are presented on methods that might allow regeneration of collector and recovery of by-product metal from the foam product.

Jan 1, 1995

By Mulong Yu, Yosry A. Attia

Beneficiation of high magnesium Florida phosphates requires ultrafine grinding to liberate the dolomite (the main source of magnesium), and a separation process capable of dealing with ultrafine sizes such as selective flocculation. The objective of this study was to investigate the feasibility of separating dolomite from apatite ultrafines by selective flocculation. To achieve this objective, selective polymeric reagents to either dolomite or apatite must be first designed and synthesized. This challenging task was accomplished by carefully selecting complexing/chelating agents which are selective to either the Ca or Mg ionic sites on the minerals, and incorporating these reagents into the structure of long chain water soluble polymers to obtain either selective flocculants (with high molecular weight, MW, polymers), or selective dispersants (with low MW polymers) to either the dolomite or the apatite particles. Synthesis and testing of these polymers on individual and mixed mineral slurries, and on a sample of natural high magnesium phosphate ore, have been attempted and the results are described in the paper. The preliminary results showed encouraging signs for the feasibility of selective flocculation separation of dolomite from apatite.

Jan 1, 1993

By Tetsuji Hirato, A. J. Monhemius, Yasuhiro Awakura, G. W. Warren, E. Peters

An electrostatic pseudo-liquid membrane technique, in which extraction and stripping take place simultaneously in a single reaction vessel using an electrostatic dispersion, was applied to recover Ni(II) from aqueous 0.1 kg m-3 Ni(II)(as NiSO4) – CH3COONa solutions, and the Ni(II) ions were concentrated by a factor of 9 into an aqueous 1.0 kmol m-3 HCI solution using D2EHPA as an extractant at the applied voltage of 3.7 kV for the dispersion. When the process of ESPLIM proceeds favorably, the concentration of Ni(II) in the upper part of the organic phase of the reaction vessel is lower than that in the lower part. In addition, the concentration of Ni(II) in the organic phase of the extraction chamber is higher than that in the stripping chamber. For the stable operation of this process, the stripping rate must be greater than the extraction rate to prevent the excess accumulation of Ni(II) in the organic phase which leads to the poor dispersion of the aqueous phase.

Jan 1, 1993

By David A. Gulley

One of the advantages of the market¬place, economists believe, is that it automatically generates information which would otherwise be hard to come by. For example, supply and demand signals imply something about private and social sacrifices and benefits. This information is seldom perfect, and can neglect some costs and benefits, but it nevertheless is crucial data. Moreover, marketplaces can also eliminate the need for some information. For example; since market participants are voluntary actors, only those transactions are culminated in which a mutual gain occurs. This eliminates the need for some cost-benefit calculations. A corollary to this standard economic doctrine is that whenever a government or other party supplants a marketplace, it must generate some of the information either lost or newly-needed. (Schultze, 1977) In 1981, following a ten-year moratorium the United States government resumed leasing of publicly-owned coal. When the government designed this program, the goal was to guide the marketplace, rather than merely to respond, as a landlord, to the market&apos;s wishes. This goal has been modified somewhat, due both to the changing political climate and to the practical difficulties of implementing so ambitious an undertaking. Nevertheless, during this period of program design and implementation, part of the challenge of creating and using the necessary information fell to the professional modelling fraternity.

Jan 1, 1982

By Y. J. Wang

Optimal sizing of a ventilation shaft is a classical subject in mine ventilation economics.. The shaft size is optimized by minimizing the sum of shaft-construction and ventilation-power costs, or owning and operating costs. The length and air quantity of the shaft are held constant, and the location of the shaft, affecting its depth, and construction and ventilation power costs, is not considered (Hartman, 1961; Lambrechts, 1974; Wang et al., 1978). This paper proposes an approach by which the location and size for a new pair of shafts (intake and return shafts) are optimized for a coal-mine ventilation network. Specifically, the problem is to determine the location and size for a new pair of shafts, and the distribution of air between the new and old shafts so that the combined cost of shaft construction and ventilation power is minimized. The shaft length or depth corresponds to the height of overburden at any shaft location. To simplify the problem, the shaft locations will be limited to the line along the main or submain entries, and the connection entries at the shaft bottom neglected. In order to calculate the ventilation-power cost, the air power of the system should be determined. This in turn requires the calculations of the air quantity and pressure of each fan in the network, satisfying Kirchhoff&apos;s laws and Atkinson equation. After obtaining the air power, the cost calculation is straightforward. In the following, we shall assume that the resistances of all airways, and the quantity for each mining section, which is controlled by adjusting the air regulator, are all known. The resistances for the shafts are determined from the estimated friction factors, and shaft dimensions and lengths. Furthermore, it will be assumed that the fans can be selected to meet the duties called for by any network solutions.

Jan 1, 1982

By J. Loredo

Wastes related to abandoned mine sites can constitute important potential pollution sources, depending on their mineralogical and geochemical characteristics and volume. Mine waste disposal sites contain a diverse variety of wastes including overburden material and waste rocks, the ore which cannot be economically removed and wastes from the smelting processes when they are accomplished at the mine site. These materials are usually heterogeneous in size, mineralogy and metal concentrations. Asturias, in northern Spain, has an extensive mining history and, in consequence, there are abundant unreclaimed and derelict mine sites with abandoned mines and spoil heaps of different age, morphology, content and dimensions. In these spoil heaps, waste materials are subjected to the intense action of a humid environment, so the instability of sulphides and sulpharsenides results in the production of acid and metal-rich leachates, which are incorporated to surface water or infiltrated through the land reaching groundwater bodies. The mineralogical and geochemical characteristics of the stored materials are key data to evaluate if they represent an environmental risk. Mineralogy and geochemistry of wastes and the particular specific environmental conditions of each site affect the rate of weathering and therefore the metal release. The characterisation of mine wastes is a necessary step in order to establish suitable assessment strategies with the aim of reducing the leaching, transport and widespread of ecotoxic elements from mining wastes to the environment (surface water, sediments, soils and air). As a consequence of the weathering of As-rich mineral phases, high arsenic contents are commonly detected in effluents from mine voids and spoil heap leachates.

Jan 1, 2006

By Victor F. Hollister

Porphyry copper deposits can be categorized into three models for purposes of prospect evaluation: Breccia-pipe, modified Lowell and Guilbert, and diorite models. The modified Lowell and Guilbert model is normally associated with a quartz-bearing intrusive and a potassic, phyllic, argillic, and propylitic alteration sequence. Variations can occur in the alteration zones of this model that range from orthoclase-rich (Kalamazoo, Silver Bell, and Mineral Park) to ortho- clase-deficient (Petaquilla and Bougainville) potassic zones. The unifying features of the model are the presence of a phyllic zone and a quartz-bearing intrusion. The breccia-pipe model (Toquepala) is characterized by structure and alteration related to or controlled by breccia. Where tourmaline occurs in the breccia, the identity of the model is usually clear. However, if tourmaline is not commonly developed in the breccia (La Caridad), the deposit can be misidentified as to model. Porphyry copper deposits associated with quartz-deficient intrusives, whether these are calc-alkalic diorites or alkalic plutons, are characterized by alteration suites distinct from those of the modified Lowell and Guilbert model. These have been generalized as diorite model porphyry deposits. Because alteration and mineralogical development in diorite model deposits is distinct from that of the modified Lowell and Guilbert, ore guides and exploration tactics differ for the two models. The reprint that follows describing the three prospecting models summarizes their features. It is to be emphasized that these are models used in exploration for specific deposit types and are not genetic, tectonic, or geographic models. Porphyry copper deposits can be metamorphosed. Gibralter is an example of a Lowell and Guilbert model deposit that has undergone regional metamorphism.

Jan 1, 1991

By John T. McDonough

The Climax Mine of AMAX&apos;s Climax Molybdenum Division is currently producing approximately 34,000 tons of molybdenum ore per day from two underground levels (see Figure I), and initial design is underway for the next deeper (1200) level. The aim of this report is to present the methods of site evaluation used at Climax for cavability determinations and underground support design. Climax succeeds with its panel caving system of mining (Julin, 1973) (Figure 2) largely because of the presence of pervasive geologic structural discontinuities. The stockwork ore body at Climax was formed by the multiple intrusion of mid-Tertiary rhyolitic magmas into Precambrian granite, schist and gneiss, and the hydrothermal emplacement of molybdenite into the network of fractures that were generated during the forceful upward intrusion of magma. Subsequently, intrusive events that were more deeply seated refractured the overlying, ore- bearing stock and propagated a complex system of axial and radial fractures. Post-ore movement along the Mosquito Fault (Wallace, 1968) and its associated stranded shear zones further fractured the ore body and disordered the existent geologic structure. The result of these structural events is a brittle, crystalline ore body that is transected by a complex pattern of faults, shear zones, and joints that augment cave initiation and enhance comminution of the ore blocks. Generalizations can be made about the structural trends within the ore deposit (King, 1946; Kendorski, 1973), however, the intensity and orientation of geologic structure is by no means uniform throughout the ore body. The relative intensities of silicic and argillic alteration are also highly variable (Vanderwilt and King, 1955). As a consequence, no single rock-mass model suffices as a standard for mine design, and site characterization for cavability and support design is a continuous process.

Jan 1, 1977

By Anna Marabini

This paper provides a summary of the studies performed over a period of more than fifteen years by the Italian National Research Council&apos;s Mineral Processing Institute in Rome to develop applications for the use of chelating reagents in the flotation of metallic minerals. A description is given of the various phases through which the studied progressed, starting with the combined use of commercial chelating reagents and a neutral oil and then moving on to the synthesis of new long-chain chelate collectors for the flotation of sulphide and oxidized Pb, Zn and Cu minerals. After a series of preliminary tests which confirmed the possibility of floating various metallic minerals with commercial reagents containing chelating groups exerting specific action on given cations, the studies were addressed to the development of a theoretical method of choosing chelating groups that exert selective action on one metallic mineral rather than others. The theoretical approach was based on thermodynamic data concerning the chemical equilibria in solution. The validity of the method has been proved in numerous cases by flotation tests on pure minerals. Subsequently the research was directed towards the design and synthesis of reagents with a mixed aliphatic-aromatic structure containing chelating groups for Pb and Zn and an alcoxyl chain of various length, position and configuration. The flotation results obtained on oxidized and mixed Zn-Pb ores provided interesting pointers for designing the nonpolar portion. The structural criteria identified via these studies were interpreted on the basis of chemical and steric considerations. A description is given of a new synthetic chelate collector which is effective in the selective flotation of Cu minerals from complex sulphides. The fact that this reagents is more selective than xanthate is demonstrated by comparative flotation tests on actual ores.

Jan 1, 1994

By Sriram Padmanabhan, Jan M. Mutmansky

The subject of quartz occurrences in respirable coal mine dusts has been of increasing concern in recent years. The primary impetus for this concern has been provided by better measurement technology that has detected an increased number of mines with high quartz content in their respirable dusts. This paper presents the results of statistical analyses of quartz levels in multi-stage impactor samples from eighteen different coal mining sections located in Pennsylvania, West Virginia, Ohio, Illinois, Kentucky, Colorado and Utah. The quartz and kaolinite determinations were then determined by combining impactor stage loadings to provide larger dust masses and applying the infrared spectrometry procedure outlined in Bureau of Mines/MSHA Method P7. The results will be presented using two categories of data collected during two separate phases of the research: (1) quartz concentration data from mines where quartz was known to be present in relatively high concentrations, and (2) quartz concentration data from mines chosen at random. The aspects of the occurrence of quartz in coal mine airborne dusts that will be reported include the size dependence of the quartz content, quartz variations with location in the mining section, and variations due to mining region. The results of the study show a strong pattern of size dependence of the quartz content in mines for which high quartz concentrations exist. A similar, though less pronounced, pattern exists in mines chosen at random. Quartz levels appear to have a varying relationship to section location and strong geographical patterns do not appear to exist in the data collected. Kaolinite content was found to be similar to that of quartz with patterns that are somewhat more consistent.

Jan 1, 1989

By R. N. Chakravorty

It is well established that coal can react with oxygen in air at ambient temperature and as a result heat is produced. If the heat is not fully dissipated the temperature of the coal mass will increase, thereby enhancing the rate of oxidation with a greater production of heat. If this phenomena continues, the coal mass can ignite under favourable heat accumulation conditions. A number of mine fires are caused each year due to this phenomena, commonly known as spontaneous combustion. The early detection of spontaneous combustion is of prime importance to mining engineers since any fire which could be detected at an early stage may save the mine from considerable damage and subsequent loss of production. Obviously, there is no single general criteria by which one can assess whether the under- ground mining of a coal seam will result in liability to spontaneous combustion. This has made it imperative to develop systems for the early detection of heating and to follow its development. In recent years considerable advances have been made in the design and development of methods for the early detection of spontaneous combustion. The Mining Research Laboratories (CANMET) is presently investigating the problem of spontaneous combustion in coal mines with Kaiser Resources Ltd. at their hydraulic mine at Sparwood, B.C. on a co-operative basis, and some of the work was described earlier in the Canadian Institute of Mining & Metallurgy Bulletin (1,Z). This paper summarizes and updates the work done by CANMET on the detection of spontaneous combustion in coal mines.

Jan 1, 1980

By G. Davey

High speed stirred milling is a relatively new method of grinding in the metalliferous process industries. However it has been it has been in wide spread use in the industrial mineral field for over 30 years for various minerals. Many existing metallurgical operations are looking to maximize economic return from existing deposits, requiring new thinking and technologies. The operating experience of two existing copper operations will be covered to show the effect of the introduction of the Metso Stirred Media Detritor (SMD) a new type of high speed stirred mill. Both operations have derived significant metallurgical benefits from the introduction of this new technology. The benefits and process difficulties are covered and explained.

Jan 1, 2003

By J. Simmons, P. Ziemkiewicz

Acid-Base Accounting (ABA) is an analytical procedure that provides values to help assess the acid-producing and acid-neutralizing potential of overburden rocks prior to coal mining and other large-scale excavations. This procedure was developed by West Virginia University scientists during the 1960s. After the passage of laws requiring an assessment of surface mining on water quality, ABA became a preferred method to predict post-mining water quality,and permitting decisions for surface mines are largely based on thevalues determined by ABA. In order to predict the post-mining water quality, the amount of acid-producing rock is compared to the amount of acid-neutralizing rock, and a prediction of the water quality at the site (whether acid or alkaline) is obtained. We gathered geologic and geographic data for 56 mined sites in West Virginia, which allowed us to estimate total overburden amounts, and values for maximum potential acidity (MPA), neutralization potential (NP), net neutralization potential (NNP), and NP/MPA ratios for each site based on ABA. These values were correlated to post-mining water quality from springs or seeps on the mined property. Overburden mass was determined by three methods, with the method used by Pennsylvania researchers showing the most accurate results to actual overburden mass. A poor relationship existed between MPA and post-mining water quality, NP was intermediate, and NNP and the NP/MPA ratio showed the best prediction accuracy. In this study, NNP and the NP/MPA ratio gave identical water quality prediction results. Therefore using NP/MPA ratios, values were separated into categories: <1 should produce acid drainage, between 1 and 2 can produce either acid or alkaline water conditions, and >2 should produce alkaline water. On our 56 surface mined sites, NP/MPA ratios varied from 0.1 to 31, and six sites (11%) did not fit the expected pattern using this category approach. Two of eight sites with ratios <1 did not produce acid drainage as predicted (the drainage was neutral), and four of 40 sites with a ratio >2 produced acid drainage when they should not have. These latter four sites were either mined very slowly, had non-representative ABA data, received water from an adjacent underground mine, or had a surface mining practice that degraded the water. In general, an NP/MPA ratio of <1 produced acid or neutral drainage sites, between 1 and 2 produced mostly alkaline drainage sites, while NP/MPA ratios of >2 produced alkaline drainage with a few exceptions. ABA is a good tool to assess overburden quality before surface mining and to predict post-mining drainage quality after mining. The interpretation from ABA values was correct in 50 out of 52 cases (96%), excluding the four anomalous sites, which had acid water for reasons other than overburden quality.

Jan 1, 2003