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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 R. E. Gertsch

Mechanical mining holds great promise for the mining industry. Realizing this promise depends on giving mine operators the capability to evaluate the higher production, the lower costs, and safety enhancement that comes with mechanical mining. The opportunities for low cost and high production must outset the high capital costs associated with mechanical excavation. Giving the mining industry the tools to effectively evaluate and successfully implement mechanical methods defines the challenges and directions of the mechanical mining industry.

Jan 1, 1994

By III Scotland

Genstar's underground mine at Texas, MD experienced a failure of the mine roof and subsequent damage to an underground backfill caused by surface floodwaters. A hydraulic backfilling program was developed in house to stabilize temporary repairs to the mine roof, replace 2300 yards of pneumatically stowed backfill, and complete a permanent repair to the mine roof. A flowable backfill material was developed, tested, and later marketed as the result of experience gained during this project. In addition, Genstar personnel developed backfilling techniques to meet the requirements of the repairs and completed work without the additional expense of non company services or contractors.

Jan 1, 1992

By Ulrich Maidl, Jamal Rostami, Ulf Gwildis

Tunnel Boring Machines (TBM) have more or less become the preferred method of tunneling in various ground conditions and Programmable Logic Controllers (PLC) or microprocessors are standard features on TBMs to monitor and record various sensory systems on the machine providing the possibility for machine automation and control. The data collected from these sensory systems and channeled through PLC is stored for real-time analysis or use by the operators. Based on typical construction specifications, part of the information collected in the process is shared with the project management team representing the owner. Machine data automatically acquired during TBM advance is typically processed by specialized software to offer the project team data visualization and evaluation options. Interfacing with Geographic Information System (GIS), Computer-Aided Design (CAD), 3-D geologic model, instrumentation data bases, and Document Management Systems (DMS) allows for developing Building Information Models (BIM) of the tunnel’s as-built condition. Application of Artificial Intelligence (AI) processes such as Machine Learning (ML) have already been used for analysis of data, including performance prediction of hard rock TBMs, and exhibited the potential of big data analytics in improving the productivity of the operations. This paper outlines anticipated disruptive technological advances with implications on geotechnical exploration, TBM operation, face condition tracking, subsurface risk allocation, and claims management in the future.

Jun 13, 2021

By R. Sharma

The heterogeneous distributions of nodule sizes, cover-ages and abundances and the variability of their burial und association with sediments and rock outcrops on the seafloor have emerged as crucial parameters in considering the exploitation potential of the manganese nodules in the central part of the Indian Ocean. Nodules with the long axis measuring from 20 and 40 mm (0.8 and 1.6 in.) account for nearly 60% to 70% of those evaluated from photographic and grab-sample data. In addition, 75% of the nodules (by weight) are between 20 and 60 mm (0.8 to 2.4 in.). The distribution of nodules with abundances ranging from 1 to 20 kg/m2 as well as coverages of 1 % to 90% on the seafloor are important considerations in demarcating the potential areas for nodule mining. The mining of areas with higher concentrations of nodules, such as along slopes associated with less sediment, would result in the enhanced recovery of nodules compared to areas with low nodule concentrations, such as in valleys and plains where thick sediment covers occur. The mining head will encounter substrates such as hard rock exposures, either with or without Fe-Mn encrustations, as well as soft sediment layers in the nodule fields. It must be able to collect buried nodules under sediment cover, and it must be able to negotiate uphill and downhill slopes in mining areas. Mapping prior to mining must delineate areas to he avoided and must define locations to be mined. The requirements suggest that the nodule collector must be a dynamic (active) system with sensors to detect areas of potential nodule concentrations, as well as features that are hazardous (or unfavorable) for mining operations.

Jan 1, 1999

By M. Argiantopoulou

In today?s mining environment, improving production, performance, productivity and profitability is crucial. Production, ancillary, plant and shipping equipment need to be monitored and controlled by online systems delivering production statistics and real-time information to everyone involved, including equipment operators. Traditional systems currently in use today, operate in an iterative mode constantly switching between scheduling and execution. However, the real world tends to change in ways that invalidate such advance schedules. Agent based computing has been hailed as the most significant breakthrough in software development and the new revolution in software. Agent systems are being used in an increasingly wide variety of applications, including complex mission critical systems such as Air Traffic Control. This paper presents the possible ways that multi-agent systems can be applied to mine production and rehabilitation scheduling problems with focus on real time fleet management, plant and equipment performance monitoring, downtime and delay reporting, stockpile management, personnel and equipment tracking and product distribution and transportation.

Jan 1, 2006

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 Paul D. Tomlingson

The difficult and often harsh working environment of the mining industry can stress both personnel and equipment to the extreme. Often, the unintended consequences of this environment lead to confrontations between departments, as each goes about its tasks of mining, maintaining or supporting these activities. On occasion, the confrontations may result in criticism of other departments for perceived or real sins or omissions. The offended department may not be able to change the circumstances, but can only complain while frustration persists. The most effective solutions are the actions of the mine manager. By establishing mutually supporting roles of each department and specifying conditions for the interactive conduct of maintenance, the mine manager can better assure that the inherent problems of the mining environment are neutralized.

Jan 1, 2011

By Charles U. Keranen

The Tilden Mine is an iron ore mining, processing and pelletizing facility located on the Marquette Iron Range in Michigan's Upper Peninsula. It has a designed capacity to produce 8 million long tons of pellets annually from 21 million long tons of crude. It is a partnership owned by The Cleveland-Cliffs Iron Company, Algoma Steel Corporation, LTV Steel Corporation, the Steel Company of Canada, Wheeling Pitts- burgh Steel Corporation and the Sharon Steel Corporation. Cleveland- Cliffs manages and operates the Tilden. The crude ore averages 35% iron and is primarily non-magnetic iron oxide and silica. The major ore mineral is martite. Hematite, earthy hematite, goethite and magnetite are also present. The principal gangue mineral is chert. The ore grains are mostly in the 10 to 25 micron size range which necessitates very fine grinding for liberation. The concentrating process is the most complex one used in the iron ore industry. The unique technology for Tilden was developed in the mid and late 60's. The design and construction occurred in the early 70's and operation of the first phase which was of 4 MLTPY capacity began in October. 1974. Expansion of the facility to the current 8 MLTPY capacity was completed in 1979. Chemicals are the key to the beneficiation process at the Tilden Mine. The flowsheet utilizes selective flocculation - desliming, cationic silica flotation and concentrate dewatering by thickening and filtering. Nine different process chemcals are used. The control of the reagent feed systems is highly auto- mated. The entire concentrator is operated from a central control room. The concentrator flow diagram is presented in figure 1. The plant consists of 12 primary autogenous grinding lines, a common crushing circuit to handle an intermediate product within the primary grinding section, 24 pebble mill lines with cyclones and deslime thickeners, 12 flotation lines, 4 concentrate thickeners and slurry tanks, 8 lines of filters with six machines per line, and 2 tailings thickeners. A pumping system was installed in 1980 to permit the direct return of tailings thickener overflow water back to the reuse water pumphouse.

Jan 1, 1986

By O. A. Bascur

An expert process operation advisor system can increase plant efficiency, even in a complex, natural environment where not all elements of the production process can be measured directly. This system, develaped and tested in a Frasch process sulphur mine, monitors key process variables with extended qualitative pattern processing and provides on-line advise to the operators of sulphur production wells. An expert system framework captured common sense rules generated from years of experience obtained in the operation of a sulphur well monitoring system. The existent operating procedures were enhanced by process analysis using a qualitative modeling approach which provided extended rules for on-line classification of a well operational status and an expert alarm system. The methodology for development and implementation of the process advisor is presented in this report. Qualitative process modeling, statistical process control and heuristics were incorpomted into the process advisor resulting in a more efficient use of heat, an extended well operational life and the resulting cost savings. The computer process advisor also allowed the operator to concentrate his attention on the weak wells or wells in trouble. A process management system improved plant operation by automatically storing well data into a commercial database for operator validation. The enhanced relational data base system provided valuable and timely information for planning and decision making. The synergistic combination of on-line process analysis tools, expert control systems and database technology is shown to facilitate the flow of materials, energy and infomation in a modern plant.

Jan 1, 1990

By M. C. Roberts

The consumption of industrial minerals, like most other commodities produced from the earth, depends on the demand for the goods and services that use these materials. Minerals are not generally used directly by final consumers (table salt is a notable exception) but instead are used to either make products that are then purchased by customers, or the minerals are used to make industrial products that eventually contribute towards producing other goods and services. Therefore the demand for industrial minerals in most uses is derived from the ultimate demand for goods and services by consumers. The problem for producers of industrial minerals is that the demand for their mineral product fluctuates greatly in response to the changes in the production of goods and services over the course of the business cycle. In this respect, the producers of industrial mineral are innocent victims, subject to market fluctuations outside of their control. Because the demand for most minerals depends on the demand for the product and because minerals typically make up a minor portion of the costs of producing the product, changes in the price of the mineral often do not influence demand for it to a significant degree in the short run. This is described as a very low price elasticity of demand, as shown by the steep slope of the hypothetical demand curve in Figure 1. This demand curve shows that changing the price of the mineral does not alter the quantity demanded very much, but shifts in the demand curve will be the important determinant of the quantity of the mine.ra1 that is sold. The shifts are caused by the changing demand for the products using the mineral over the course of the business cycle.

Jan 1, 1994

By H. A. von Schonfeldt, H. Douglas Dahl

INTRODUCTION During the past decade, significant pro¬gress has been made in applying rock mechanics principles to mine design problems by a great number of researchers. Some of these new techniques have found their way into the engineering and planning offices of the operating mine. In spite of these advances, however, the application of rock mechanics in the day-to-day mine planning and design of our domestic coal mines is rela¬tively rare. There are a number of reasons responsi¬ble for this relatively slow progress, not the least of which is the question of how to measure the success or cost effectiveness of a sizable rock mechanics effort in an opera¬ting mine. Firstly, the properties of geologic materials generally vary over a wide range and it is, therefore, difficult to assess whether an improvement in the mining conditions is due to a design change or due to a change in the geologic conditions. A second reason for the slow acceptance of rock mechanics in engineering thinking is the fact that some of the concepts are quite difficult and that physical evidence of their validity to mine design is still rare. Thirdly, com¬munication between research, engineering and applications oriented people appears to function only intermittently. In our view, however, the most important impediment lies in the "state-of-the-art." Exactly how much can rock mechanics help the mine operator? The best that rock mechanics can do at present is determine whether one approach is better than another when weighed against some design objective (stress, strain, deformation). We cannot determine the abso¬lute best ground control design -- only what is better. If ground control is lost, the statement that "it's the best one we looked at" means very little to the harried operator. While the "state-of-the art" has advanced a great deal, it has certainly not been reduced to an engineering matter in that design hand¬books are available -- they are not. The success of a rock mechanics program, there¬fore, can be determined only over a long period of time of continuous effort.

Jan 1, 1977

By R. Tanaskovic

The objective of study of climatic conditions in underground mines is to create a working environment suitable for normal development of operations. Disregarding the fact that the development of equipment and technology, especially during the past decade, made the work in underground mines much easier, it is observed, according to the number of professional publications, that increasing attention is devoted to the study of climatic operating conditions in mines of many countries. This indicates that the climatic operating conditions are closely connected with productivity, and in turn with mine production profitability, in addition to the protection of manpower health and working capabilities. Usually, the concept of unfavourable climatic conditions of operation implies increased mine air temperature and humidity and low air flow rate, resulting in impeded heat exhange between human organism and working environment. As known, above phenomena are present in deep underground mines where the heat problem exceeds the-problems related to other features of natural conditions of mining. On the contrary, unsuitability of climatic operating conditions in mines with shallower mining depths is manifested by inadequate heat, particularly during the cold winter period. The two stated aspects of unsuitable climatic operating conditions are not solvable only by mine ventilation, so the former case requires cooling and the later one heating of the air used to ventilate the pit, or part there of where the phenomena are manifested. Study of climatic operating conditions in mines is, due to the number of factors involved, a complex and time consuming task, and this was, among others, one of the reasons for inadequate study of these problems in many mines. However, it is evident that further development of mine production imposes the need to make the climatic operating conditions in mines similar to those existing in other activities, where increasing attention is being devoted to the improvement of these conditions. Development of mining industry in Yugoslavia, particularly over the past decades, caused several of our mines to approach mining depths where the heat regime has a major influence on climatic operating conditions. This imposed the need to determine and investigate heat regime parameters, especially those that cause unsuitable operating conditions. The results of such investigations in the case of the deep part of Lead and Zinc Mine "Trepca" - Stari Trg are briefly reported in this paper.

Jan 1, 1980

By Jim Salley, Mohammad Saleem, Indra Banerjee, Kevin Sapp

"On underground construction projects, effective Quality Management is essential for ensuring facility durability, life cycle performance and low maintainability. Furthermore, follow on contracts also rely on an effective quality management system for interface congruency. An effective Quality Management System (QMS) is also essential in mitigating risks and meeting schedule and budget performance objectives. For the past 15 years Central Puget Sound Regional Transit Authority’s Link Light Rail extension has successfully completed over 10 miles of twin bore tunneling and associated underground features including cross passages, deep sump structures and shafts. After the completion of each segment, lessons learned have successfully been implemented to improve the quality of delivered projects. This paper presents the Sound Transit QMS with regard to a number of project elements of tunnel construction projects, with specific focus on quality performance of slurry wall construction, TBM tunnel excavation assessment, segment production and segmental lining installation, and other associated construction features. A collaborated total QMS will be presented in this paper that will serve as a guide for successful implementation of Quality Assurance and Quality Control processes. INTRODUCTION Implementation of a robust Quality Management System reduces defects, errors and omissions, identifies and addresses nonconformance in a timely manner and increases stakeholder confidence in the project. In fact and effective QMS helps ensure that optimal project outcomes are realized both in terms of project delivery and life cycle performance. The two key components of QMS are quality control and quality assurance. Quality Control (QC) is the procedure implemented to achieve a certain level of quality and ensure that products, processes and services meet specific requirements. Quality Assurance (QA) activities are carried out to evaluate the effectiveness of the quality control measures and ensure that the QC process is working. A team obligation that recognizes that quality is built into every aspect of a project is the basic concept of a successful QMS."

Jan 1, 2016

By S. W. Beckman, L. Williams, A. E. Seep, R. Fischer, J. Hubbard

Introduction The Summitville Mine located in southwestern Colorado was added to the National Priorities List in June of 1994. Summitville was the site of mining operations that began in 1873 with the discovery and development of gold placer and lode deposits in the late 1800's. The mine site is located about 25 miles south of Del Norte, Colorado in the San Juan Mountains adjacent to the Rio Grande National Forest at an approximate altitude of 11,600 feet. The site was mined for gold, silver and copper between 1873 and 1947. The Summitville Consolidated Mining Corporation, Inc. (SCMCI), a wholly-owned subsidiary of Galactic Resources, Ltd of Vancouver, Canada ran a large tonnage open-pit mine and cyanide heap leach operation from 1986 to 1992 (Pendleton and Posey, 1992) During the mine operation by SCMCI, approximately 10 million tons of gold ore was mined, crushed and stacked on a lined leach pad. Heap leach operations experienced water balance and unplanned solution discharges from the start of the mine life. Despite the production of 249,000 troy ounces of gold during the mine operation, SCMCI was unable to meet remedial requirements and notified the state of Colorado of its intention to file a Chapter VII bankruptcy in December 1992. The EPA Region VIII Emergency Response Branch took over site operations on December 16, 1992 to prevent a catastrophic release of hazardous substances to the environment. The multiple contamination sources at the mine site are due to both historic and SCMCI mining operations. Emergency response operations at the site have prevented releases of severely contaminated solution and a permanent treatment for all waste units at the site is under investigation. A Request for Proposal (RFP) was issued in October 1993 by Environmental Chemical Corporation (ECC) at the Request of EPA Region VIII, Department of the Interior and Bureau of Reclamation. The RFP requested that interested companies provide information on their ability to implement innovative treatment technologies to improve treatment efficiency and reduce treatment costs for remediation of the heap leach pad (HLP) spent ore and ore leachate solutions. Dames & Moore and Pintail Systems, Inc. (PSI) jointly submitted a proposal suggesting application of biotreatment processes for detoxification of cyanide in spent ore and HLP leachate solutions. The proposal was accepted for pilot and field demonstration under the SPA Superfund Innovative Technology Demonstration Program (SITE) with additional funding from EPA Region VIII. This report discusses the test program and results of a Focused Feasibility Study which demonstrated biotreatment processes for spent ore cyanide detoxification.

Jan 1, 1995

By K. Bragg

During the last several years considerable discussion has taken place on the long term aspects of uranium tailings management. These discussions have centered around a variety of topics which in turn lead to a variety of opinions. In order to come to grips with the various differences of opinion and points of view, the Atomic Energy Control Board has decided to prepare, as an interim measure, a list of proposed close-out criteria for uranium tailings management facilities. It is important to keep in mind that the criteria set out in this paper are proposals and are intended to initiate a continuing dialogue between the uranium mining industry and the various regulatory and government agencies. It is envisaged that this dialogue would continue for a period of from six to twelve months after which some final form of these criteria would be issued and applied to the active uranium mining facilities. In attempting to understand the reasons why the Atomic Energy Control Board has decided to propose these criteria now instead of at some future point in time, it is necessary to look at a number of existing facts. One of the most important of these is that something in excess of one hundred million tonnes of tailings currently are placed in various tailings management facilities. Furthermore, the rate at which tailings are being deposited into such management facilities is on the increase and this increase is expected to continue over the next five to ten years. The management of these tailings is currently covered under the Mine Facility Operating Licences issued by the AECB. Implied within these licences and supporting documents leading to them, are requirements for the conceptual approach to be used at abandonment. There is however, no current requirement for a detailed study on the engineering or financial aspects of such abandonment procedures. This is a gap which the Board feels must be addressed. There are, at this time, various initiatives underway both in Canada and within the international community which are attempting to address the problems and concerns of the very long term management of tailings. For example, current research in Canada which is composed of two components, one by the AECB dealing with purely regulatory aspects and a second major coordinated program under the direction of the Department of Energy, Mines and Resources and in particular by CANMET is going to deal with the technical problems. On the international scene

Jan 1, 1980

By G. Camposano, J. Aponte, B. A. Ferguson

The paper covers mining operations and preparation of the ore prior to metallurgical treatment in the Process Plant. Mining operations are primarily concerned with the delivery to Ore Preparation of a balanced ore feed within fairly rigid specifications as to both ore type and chemical analysis. The mining method, systems of geological and engineering control, and the equipment employed are therefore reviewed in this context. In Part One of the paper the physical and geological characteristics of the orebodies, including the varied nature of the ore itself, are first described. Orebody evaluation, the calculation and classification of ore reserves, mining planning and forecasting to ensure continuity of production are covered, and the particular problems presented by sampling, the erratic distribution of ore values and the variation in the density of the ores are also mentioned. Mine design and ore excavation practice are described, together with the way in which they have evolved with recent developments in modern mining equipment. In Part Two of the paper, a detailed description of the Ore Preparation plant is given, centred around the concept of rubbling as a means of separation of the barren hard boulders from soft lateritic ore. Ore blending and ore reclamation operations are explained followed by a detailed description of the drying and crushing plant. The importance of the control of moisture content and ore sizing in the feed to the metallurgical plant is emphasized.

Jan 1, 1979

By Ruifeng Li, Yanghui Ren, Hua Gao

"Since entering the new century, China’s coal industry has witnessed the rapid development, and provided a reliable energy supply for the national economic and social development. But after the “golden decade” of rapid development, the coal industry now is facing overcapacity, low industrial concentration and production efficiency, high pressure of production safety and environmental protection and other prominent issues. Based on defining the connotation of highly-efficient recovery of coal resources, this paper established the relevant 8 indicators to reflect the highly-efficient recovery level of coal resources, summarized the present situation of China's coal resources recovery and the main problems, analyzed the development environment of China's coal industry under the new situation, and finally put forward the strategic measures to promote highly-efficient recovery of coal resources in China.1. Background Coal is the main energy in China. Since entering the new century, China's coal industry has made significant progress, and the level of production safety, resource recovery rate and mining mechanization increased significantly, which provided a reliable energy supply for the rapid development of the national economy. However, due to the changes of China's economic environment, slow growth of energy demand and other factors, some prominent contradictions in the coal industry have significantly restricted the healthy development of the industry. The first problem is serious overcapacity. In the past few years, 16 industries including coal, electric power, chemical and others have invested in coal mines. It is reported (Han 2016) that only during the nine years from 2005 to 2014, the fixed assets of coal industry increased totally more than 3.3 trillion RMB, which brought a large number of production capacity. Affected by the slowdown of economic growth and energy structure adjustment, Chinese coal demand has reached the peak platform and caused the overcapacity of coal supply, so shutting down the backward capacity is the most important task in the future. The second problem is the low efficiency of coal production. There are about 4.3 million coal mine workers in China, and the annual coal production per capita is less than 900 tons, while it was reported (EIA 2016) that the annual production per capita in the United States is more than 10 thousand tons. The third problem is that the green coal resources are not rich. Among the 1.53 trillion tons proven reserves, only about one third are green coal resources in accordance with the principle of ""safety, technology, environment and economy"". The coal resources with high quality and easily mining conditions are not abundant."

Jan 1, 2017

By Gerard P. Hand

The use of graphite in industrial applications is one of the oldest in the world. Yet, it is one of the fastest-changing technologies today. Graphite was first used centuries ago in developing writing instruments and as a raw material in crucibles used in melting metal. Today, graphite is used in some of our most demanding industries. These include aerospace, electronics and automotive applications. Graphite usage has historically been split between the natural and synthetic forms. Figure 1 shows the breakdown of natural graphites and synthetic graphites used. The usage of natural graphites and synthetic graphites is split fairly evenly, although the applications are quite different. Figure 2 shows the breakdown of applications using natural graphite. The largest application is the refractory industry. This includes refractory brick and plastics, crucibles, shrouds and other refractory parts. This main application uses roughly 50% of all natural graphite. The refractory industry is an important application for natural graphite. However, the refractory markets have been struggling for several years. As demonstrated in Fig. 3 (Semler, 1996), the production of refractories in tons per year has declined by more than 32% during the last 25 years. Refractory prices have actually risen on a dollar per ton basis during that same period as the product mix has shifted to the value-added side. Raw material and production cost increases, inflation and other related costs have kept profitability at low levels for the industry. Furnace linings that once lasted 1,000-2,000 heats now last 8,000-12,000 heats. This means that tonnage requirements have gone down and quality requirements have gone up for graphite suppliers. Therefore, new opportunities and applications must be developed if the graphite industry is to grow. Synthetics are the other major forms of graphite. There are two forms of synthetic material currently used. One is the traditional type. It is made from the turnings of graphite electrode production. The second was developed in the mid-1970s in response to a shortage of conventional synthetic graphite. This occurred by a breakthrough in thermal technology. This new technology purifies, desulfurizes and graphitizes petroleum coke on a continuous basis at temperatures of more than 2,500° C (4,532° F). This product is called desulfurized petroleum coke (Desulco). It now accounts for about half of the synthetic type material used in the United States. Figure 4 shows the breakdown in the use of synthetic types of material by application. The largest requirement is for use as a carbon addition in iron and steel. This is followed by alkaline batteries and friction materials. Current technological opportunities New opportunities for graphite products are now being developed. These new areas are made possible due to the advances in graphite thermal technology. The ability to purify and modify graphite and carbon products is the key to future growth in the graphite industry. New, higher-purity, more consistent graphite products are leading to enhanced performance in current applications. They are also opening the door to new applications.

Jan 1, 1997

By A. P. Cook

Methane drainage on a mine-wide scale is a relatively new technology to South African coal mines. Shallow seams and apparently low methane contents have been assumed to result in less methane problems than experienced in other countries. The introduction of deeper mines however, has now resulted in methane drainage taking on a higher priority. Methane contents in the region of 12 m3\t have resulted in one colliery introducing drainage as a ventilation support. Although a low seam permeability initially indicated reduced potential for drainage, early borehole flows of 90 m3\m\year have since increased to 450 m3\m\year. Rapid inflow of methane into goafs and sealed areas from seams surrounding the main production seam at another colliery have warranted extensive evaluation of the methane properties of these seams with the projected introduction of predrainage from surface. Methane pressures in excess of 1000 kPa and contents in the region of 10 m3\t again give methane volumes suitable for drainage. Coal seam drainage ahead of mining is becoming more significant and is likely to see an increase in the near future. INTRODUCTION Methane gas is an everpresent hazard associated with underground coal mining. Safe working levels of methane in the mine atmosphere are normally maintained by ventilation practises, ensuring sufficient dilution of the gas. However in some cases the ventilation must be assisted by methane drainage, either from the mined seam, or from adjacent seams and strata, or from goafed areas. South African collieries have practised only limited methane drainage until now. Relatively shallow mining depths, and apparently low in-seam methane contents have been assumed to result in fewer problems with methane than are the normal for other countries. This is now being shown to not necessarily be the situation. Work carried out by the Coal Mining division of COMRO (Cook and Erwee, 1991) indicates South African production coal seams have very similar methane retention properties to those of coals in other countries, with seam gas contents of up to 12 m3/t. This awareness, as well as greater mining depths, and higher degrees of mechanisation, has resulted in higher priority being given to methane emission problems throughout the industry. Increased levels of safety, as well as possible commercial applications, are the main reasons for the interest now being shown in methane drainage. Not only is there possible applications in the present production coalfields, but South Africa has vast areas of coal reserves which are presently non-mineable, now being seen as possible alternative energy sources. Limited methane drainage is practised within the industry, but only on collieries that have identified specific methane problems that can be alleviated by drainage. Historically this has been restricted to surface drainage of longwall goafs, reducing emissions onto the faces. More recently, horizontal in-seam holes have been drilled, until now for bord and pillar sections, but the results are being evaluated for later application to shortwall faces. Adjacent seams pose problems at some sites and vertical and cross measure boreholes are now being considered.

Jan 1, 1993