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By Robert L. (Original by) Llewellyn

Many of the problems that occur in the preparation plant originate from practices in the mine. Impurities in raw coal can be in the seam itself or from extraneous material taken in mining from the roof or bottom. In the case of underground mines, the choice of mining equipment will affect the size consist and the amount of extraneous material included with the coal. Also, governmental regulations concerning the degree of rock dusting, gobbing underground, and cleanup have increased the dirt in raw coal. Sulfur dioxide emission standards, on the other hand, are pressuring the coal industry to clean coal more thoroughly. Coal supplied for coking purposes is nearly all upgraded by washing, while for the largest market, electric power generation, a high proportion is shipped as a raw product with processing, in whole or in part, only necessary when excess impurities are mined with the coal. This chapter will deal primarily with plants that process or wash coal to some extent (Fig. 1) and only incidentally with mines shipping raw run-of-mine coal crushed to a top size of, usually, 51 to 102 mm (2 to 4 in.), with little, if any, other treatment.

Jan 1, 1981

By D. Tolgyesi, L. P. Gignac

Mine development has evolved in the past 15 years from a human-paced system using hand-held drills and track-bound equipment to a mechanized system using specialized equipment for each component of the development cycle. In most Canadian hard-rock mines, face advance is achieved by the following sequential activities: drilling, explosive loading, mucking and ground support. The state-of-the-art for each work element is reviewed and methods for performance estimates proposed. The entire development system and its production capabilities are considered based on equipment reliabilities, spare units, haulage distances, and muck bay spacing. The effect of the number of working faces on the system's performance will also be analyzed. Manuscript not received in time for publication.

Jan 1, 1983

By R. S. Ondrey, R. A. Haney, T Tomb, R. T. Stoltz, Novakowski D. L. Chiz, E. J. Gerbec, D. J. Atchinson

Although the number of operating longwalls in the United States (approximately 100) has remained relatively constant over the last five years, longwall production levels have significantly increased and in some cases more than doubled. As a result of this production increase, control of respirable dust continues to be a problem. Therefore, the Mine Safety and Health Administration (MSHA), Pittsburgh Health Technology Center, Dust Division, initiated a study to investigate the availability and adequacy of technology for controlling dust on longwall mining operations. The study involved 23 longwall mining operations in three different Coal Mine Safety and Health Districts. Each operation was visited for a full shift. Respirable dust samples were collected on face personnel and at fixed locations along the face. Methods being used to control dust were noted, with special emphasis placed on obtaining quantitative data relative to ventilation, headgate dust controls, cutting drum sprays, external machine sprays and cutting sequence. Attempts were made to correlate dust control practices in place at the time of the visit to dust concentrations measured at the tail and on the tail shearer operator and to the average of all the dust concentration measurements from the occupations sampled. The methods used to control dust were also compared to the gamut of methods known to be available. This paper presents a discussion on the effectiveness of the methods being used to control dust and on the availability of technology for the control of dust on longwall mining operations.

Jan 1, 1991

By R. D. Begley, A. W. Khair

This paper presents an assessment of modeling techniques in predicting subsidence over longwall areas. Extensive instrumentation has been made, both at the surface and subsurface, at three longwall mines in northern West Virginia. Ground movements were monitored during a three- year period until subsidence ceased in these areas. A comparative analysis of empirical subsidence prediction techniques including graphical (NCB), profile function, influence functions (USBM, Bals', Knothe's, and zone area) will he presented. A brief geologic and topographic description of each site, along with the instrumentation and monitoring program, will also he presented.

Jan 1, 1990

By Charles A. Horne

Grinding mill circuits used for particle size reduction of mineral ores commonly use cyclones as primary classifiers. Typically, several individual cyclones are installed in a cluster (Fig. 1) where they can easily be added or valved-out of operation in order to balance classifier capacity with fluctuations in tonnage and recirculating loads as ore grades and hardness vary.

Jan 1, 1993

By D. M. Larsen

Since start-up in 1985, the Cannon Mine has produced and shipped a 170-g/ton (5 oz/ton) gold flotation concentrate to various smelters for gold and silver recovery. Several processes have been investigated to economically produce done' at the mine site from the refractory concentrate. This paper describes laboratory and pilot scale test work used in the process design and engineering. feasibility study of a 73-t/d (80 stpd) pressure oxidation and carbon-in-leach (CIL) facility. The designed pressure oxidation circuit utilizes a series of verti¬cal autoclave units operating at 170°C (338F) and 1.4 MPa (200 psig). Projected operating costs are discussed.

Jan 1, 1993

By John S. Thayer, Frederick E. Brinckman, Kenneth L. Jewett, Gregory J. Olson

Interest and research in biorecovery of metals has focused mainly on cell-based metal leaching and precipitation. However, production of non-enzymatic metabolic products by microorganisms related to metals bioprocessing also deserves attention. For example, it is well known that biogenic inorganic (e. g. H2S04 ) and organic acids play a role in metal dissolution. There are other metabolic products of microorganisms which can catalyze useful metals transformations. These include methylated metabolites such as alkyl halides which can dissolve metals from ores and also reduce certain metal ions in solution to pure metallic particles. This paper describes some of our research on metal dissolution and precipitation by such metabolites. Examples include the production of high purity elemental metal particles of gold, platinum and palladium by volatile metabolic products.

Jan 1, 1989

By Deepak Malhotra, Linda K. Baltich

The minerals business is dynamic and competitive and the economic viability and/or profitability of any mineral company depends on maximizing recoveries while minimizing costs. In order to achieve this goal, it's essential that you have a clear understanding of the current status, including strengths and weaknesses, of the operation. The authors have developed a systematic approach to plant auditing which we have used successfully at several operations. The strategy presented in this paper can be tailored to fit a wide range of audits. This flexibility is a key feature of the approach.

Jan 1, 1989

By Nopadon Mantajit, Dallas W. Davis, Somsak Potisat, Prasert Kumalachan

For centuries Thailand has been a significant, though primarily unofficial, producer of gold. Panning has been the traditional way of making a living for innumerable villagers during the December to May dry season following the harvest. During this period groups can be seen working the streams, rivers, fields and dry valleys at as many as 90 localities in 28 provinces. Attesting to their efforts are the five and a half ton solid gold Buddha at Wat Trimit and much of the gold jewelry sold in Bangkok. This traditional panning will continue, and probably become more extensive, in harmony with commercial endeavors using modern technology suitable for extraction of gold from types of deposits for which gravity separation would give very low recoveries. Several such deposits have been discovered in the course of geochemical and geological surveys conducted by the Royal Thai Department of Mineral Resources with the object of contributing to early interpretation of the results of a country-wide airborne survey.

Jan 1, 1987

By W. M. Ma, Daniel W. H. Su, K. Centofanti, Yi Luo, W. L. Zhong, Syd S. Peng

4.1 INTRODUCTION There have been numerous methods developed for predicting the final subsidence and final displacement profiles (Voight and Pariseau, 1970; Brauner, 1973a; Kratzsch, 1983). But for discus- sion purposes, they can be classified into six categories: theoretical, profile function, influence function, graphical, physical, and numerical modeling. The theoretical method employs mainly continuum mechanics theories and attempts to explain the mechanisms that lead to sur- face subsidence. Many models using nearly all kinds of material behavior have been developed. These include elastic (Salmon, 1963; Berry, 1964), plastic (Pariseau, 1968), viscoelastic (Iman, 1965), and elastoplastic (Dahl, 1969). The Profile Function Method is essentially a method of curve-fitting against the measured subsidence profiles in a particular mine or region. There are more than 20 profile functions developed empirically for nearly all major coalfields in the world. These include, to name just a few representative ones: Hungary (Martos, 1958), Japan (Hiramatsu and Oka, 1968), Russia (Avershin, 1947), United Kingdom (Wardell, 1965), and USA (Peng and Chen, 1981; Karmis et al., 1984). The NCB's graphical method in the subsidence Engineers' Handbook (1975) also belongs to the profile function method. The influence function method was first proposed by Bals (1931/1932). It was further developed in various periods and stages by Knothe (1957), Liu and Liao (1965), Brauner (1973a) and Marr (1975). This method is now widely used in various parts of the world. The physical models include sand (Litwiniszyn, 1959; Pariseau and Dahl, 1968) and gelatin (King and Whetton, 1958; Khair et al., 1986). They are used mainly to study the parameters that control subsidence behavior. The most popular numerical method is the finite element technique. It can simulate nearly every conceivable material behavior, inhomogeneity, bedding planes, anisotropy, and various boundary conditions. This versatility is absolutely necessary considering the ever-changing geologic and mining conditions encountered. In the following sections, only those methods that have been applied to US coalfields will be discussed. Furthermore, the methods for prediction of several key parameters such as maximum subsidence, maximum possible subsidence, and maximum displacement are discussed first, because they are the key parameters to be used in the profile function, influence function, and graphical methods.

Jan 1, 1992

By M. D. McInnis

The Jualin Gold Prospect is centered on Johnson Creek, approximately 40 air miles north-west of Juneau, Alaska. The property is on the southern end of the Kakuhan Range with Berners Bay immediately to the south and Lynn Canal to the west. The property is accessible directly by helicopter from Juneau or by float plane to the head of a 5.5 mile gravel road that begins on the north side of Berners Bay and terminates at the old workings of the Jualin Mine near the center of the property.

Jan 1, 1989

By John Mastoris, Shkurta Gashi, Kostis Dragasakis, Kostas Kouklidis, Halil Berisha

Water is increasingly recognized as a critical issue for sustainable development, becoming as important as carbon to corporate responsibility and reputation. Although the cement industry’s overall ‘water footprint’ is relatively small compared to other sectors, the Cement Sustainability Initiative of the World Business Council for Sustainable Development (WBCSD/CSI) has recognized the importance of water and the need to take actions towards efficient water management, with developing standardizing practices and employing a risk-based assessment approach, mostly at local level where individual facilities and activities can have implications for other water users in the area. Sharrcem, a member of the Titan Cement Group, has made significant investments to upgrade its production facilities, the technological process and apply environmentally friendly technologies. Under this frame, Sharrcem implemented a project for the construction of a Waste Water Treatment Plant (WWTP) in the Cement Plant facilities, which has been successfully operating since early 2016. This paper discusses the technology applied at the new WWTP and the results achieved already, with significant improvement in the quality of the treated water, as compared to the previous situation where untreated wastewater was directly discharged to the nearby Dimce Stream. The WWTP project is a major investment of Sharrcem that aims to improve the quality of the discharged water effluents and thus prevent potential river pollution and overall protect the environment and the health of Sharrcem employees and local community. The WWTP operates with the Sequencing Batch Reactors (SBR) technology, is fully automated and has been also connected with few households of the neighboring community to treat also their sewage water. The plant can be expanded in the future – to connect with additional households - without increasing the size of the treatment tanks. One of the benefits of this project is that by removing a variety of contaminants from water it becomes usable again, depending on the nature of the contaminants and the end use of the water treated. According to the monitoring results the treated water that comes out of the WWTP fully meets quality requirements according to the EU and local limit values standards

Jan 1, 2017

By William S. Pintz, William A. Vogely, Charles J. Johnson

This chapter on the role of minerals in developing economies is oriented toward economic policy issues. The discussion and analysis cut across the technical, economic, legal, and policy fields. The goal of this chapter is to pro- vide relevant background information important to individuals involved with the minerals sector in developing countries. Where possible, trends are shown to provide a basis for understanding the evolving role of minerals in developing economies. This chapter is divided into the following five sections: (1) characteristics of developing countries (which presents selected statistical comparisons); (2) government objectives in developing countries; (3) government policy formulation in developing countries; (4) determinants of future trends, and (5) a summary of the chapter's major points combined with the authors' view. CHARACTERISTICS OF DEVELOPING COUNTRIES There are 155 nations in the world categorized as "developing countries." In total these nations represent about one third of the value of the world's mineral production, three quarters of the world's population, and over half of the world's land surface area. The group of so-called developing countries is quite diverse and there are exceptions to almost any general observation about the group as a whole. Most definitions of the term "developing country" are based on levels of per capita income. However, if per capita income is the sole criterion used in categorization, then several oil-exporting countries would jump from the category of developing country to the category of developed country.a Obviously, this results in a poor fit with respect to other measures. In general, the majority of developing countries can be characterized by relatively low per capita income, high population growth rates, high levels of unemployment, low levels of education, short average life ex- pectancies, income distribution skewed toward the highest 20% of the population, and a large share of exports represented by primary commodities. b For the purposes of this chapter a slightly modified version of the widely used World Bank system of classification (shown in Table 1.2.1) is used. As summarized in Table 1.2.1, developing countries are divided into three main groups based on estimated gross national product (GNP) per capita. It should be noted that the high- income, oil-exporting countries have characteristics of both developing and industrialized countries; however they are included for most statistical comparisons within the group of developing countries. Of the 155 developing countries in the world, approximately half produce minerals other than common building materials, and only 32 account for more than five percent of world pro-

Jan 1, 1985

By D. S. Bird

Kennecott Utah Copper began a modernization program in 1986 that was aimed at expanding and updating mining and ore process facilities at the company’s Bingham Canyon copper mine and concentrator near Salt Lake City, UT. Major components of the project included installation of an in-pit crusher, a transfer conveying system and a new ore concentrator with a design capacity of 70 kt/d (77,000 stpd). The Copperton concentrator was commissioned in February 1988. The grinding circuit is one of its principal features. It consists of three identical lines, each with a 10.4-m- (34-ft-) diam x 4.6-m- (15-ft-) long semiautogenous grinding (SAG) mill and two 5.5-m- (18-ft-) diam x 8.6- (28-ft-) long ball mills. The SAG mills are driven by two 4.5-MW (each) (6000-hp) variable- speed dc motors through a clutch-pinion gear-ring gear assembly. The ball mills are driven by 4.1-MW (5500-hp) synchronous motors coupled through a typical clutch-pinion gear-ring gear system.

Jan 1, 1995

By Mark W. Springett

The examination of relatively well behaved distributions subject to truncation by a cutoff grade in the mine clearly demonstrates that a bias is inevitably introduced when the selection is based on the results of samples which are subject to even the most idealised error distribution. The idealised error used in this paper is assumed to be normally distributed with a mean of zero and is thus unbiased. The bias introduced can be minimised but it cannot be eradicated. A better understanding of the bias can lead to improved procedures for mine sampling, sample preparation, assaying and estimation of selection units which will not only reduce the discrepancy but more significantly will increase the efficiency of mining selection and hence profitability.

Jan 1, 1989

By Michael W. Glasson, Archie M. Richardson, Leo Gilbride, Laine Adair

Andalex Resources, Inc. recently engaged in a ventilation planning exercise that resulted in the construction of a new main fan installation to support longwall coal mining at the Aberdeen Mine. This paper documents the planning process, including underground measurements, modeling, permitting, and construction of the new fan installation.

Jan 1, 1997

By G. Pan

The production data of many mines have not reconciled geostatistical estimations based on exploration and development drilling. The discrepancies in recovered metals are sometimes as large as 30%. A number of factors are responsible for such unpleasant outcomes. A major cause, however, is the lack of geological controls in the implementation of geostatistical techniques. Geological modeling establishes geological constraints and mineralization/ore envelopes. Geological constraints are usually established through drill hole interpretation. Mineralization and ore envelopes have been delineated manually based on assay grades. The issues associated with manual methods are: •Time requirements . •Inconsistent dilution. •Uncontrollable implementation variance. Although the time issue may not be a big concern for some companies, the other two have been responsible for many undesired estimation errors. A new geostatistical approach described in this study is designed on the basis of indicator and ordinary kriging. The central component of the method is the procedure for automatic delineation of mineralization and ore envelopes. The method, referred to as probability assigned constrained kriging (PACK), is demonstrated on a Carlin-type gold deposit. The estimation results are compared to blast-hole based production panels, showing that the estimated tonnage is about 2.1 % higher than the actual production, and the average grade is about 2.4% lower.

Jan 1, 1995

By J. D. Miller, C. L. Lin

The appropriate software and hardware necessary to adapt an X-ray CT analyzer for the determination of coal washability was developed and successfully tested for well-characterized samples under laboratory conditions. Evaluation of the CT-based analyzer under simulated on-line conditions is also presented to verify the on-line capabilities of the newly developed X-ray CT analyzer for the control of coarse coal cleaning circuits. The investigation shows that the data obtained from CT washability analyses compare favorably with experimental sink float data. Further, image frequency was considered to evaluate the CT-Based coal washability analyzer for simulated on-line conditions. Specifically, the number of observations (image spacing) needed for accurate sampling and the total time required to perform the calculations for a representative data set were determined. Key words: Coal washability, Computer simulation, X-ray CT analysis

Jan 1, 2003

By Neil Hillhouse

The Porgera gold district, like many other large gold deposits, has a long history of awareness, but only in the last five years has a geologic understanding of the district permitted the discovery of economically attractive gold reserves. The following sequence of events highlights the various significant steps in the evolution of the discovery process. The history of the district goes back about 50 years, and for several decades it was known only for its placer gold. Gradually, as gold became a more interesting metal, more and more attention was centered on the district. The sequence of events does not overstate the problems caused by isolation and climate, but the reader can imagine the difficulties inherent in such an area.

Jan 1, 1990

By Michael Hitch, Jiajie Li

Dramatical increase in the CO2 concentration in the atmosphere has led to the climate change, which poses a significant threat to human life on Earth. CO2 sequestration via mineral carbonation is the one of the most effective method for mitigating global warming, and is the only way that could store CO2 permanently. In recent years, integrating mineral carbonation via ultramafic mine deposit has received significant attention due to its high potentiality towards commercial application. This review compiles the work conducted by various researchers over the last few years on integrated mineral carbonation processes in mining industry, which use the mine waste materials as CO2 feedstock for mineral carbonation. This paper initially introduces the basic theory of mineral carbonation, with a brief description of various techniques that enhance the rate of mineral carbonation. The enhanced mineral carbonation strategies include pre-treatment of feedstock by thermal, chemical and mechanical activation, and carbonation in a direct or indirect carbonation routes under gas/solid phase or aqueous phase. This paper then introduces the scope of application of integrated mineral carbonation. This includes the types of mine suitable for integrated mineral carbonation, the properties of mine waste materials preferable for CO2 sequestration, and the worldwide locations potentially viable for integrated mineral carbonation. Moreover, this paper critically reviews and discusses the integrated mineral carbonation process in mining industry. The integrated mineral carbonation processes include modified passive carbonation techniques at tailing dams, and ex-situ carbonation routes using fresh tailings. The focus of the discussions is the role of reaction condition on the carbonation efficiency of mine waste with various mineralogy, and the drawback of each integrated mineral carbonation process. All the discussions lead to the suggestions on the technology improvement in the integrated mineral carbonation process. Finally, this paper reviews the economical assessments on the existing integrated mineral carbonation process. Literature to date indicates that the value-add by-products (i.e. recovered metals, valuable carbonated products) play an important role in commercialization of an integrated mineral carbonation process.

Jan 1, 2017