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By Edward J. Miller

Explosions and fires are without a doubt two of the most feared occurrences in modern underground mines. When they result in loss of life or substantial property damage, they usually gain world-wide media attention and have, on occasion, provided the impetus for legislative action. The very involvement of the Federal Government in mining was the result of a series of explosions which resulted in the loss of hundreds of lives. Fortunately, explosions of this magnitude are rare. Fires and explosions of lesser consequence are, however, more common and their severity may be more a matter of luck than anything else. The publicity which these events receive is usually restricted to the area immediately surrounding the mine and a1 though MSHA and sometimes the state prepare reports of their investigations, the general mining community is quite often aware of the circumstances surrounding these occurrences. This paper will discuss some of these "lesser" explosions which have occurred recently. These explosions have sometimes occurred in sealed or otherwise inaccessible areas of the mine involved, where conventional ignition sources such as electrical power were not present.

Jan 1, 1987

By Victor F. Hollister

Porphyry-type deposits are characterized by mineralization in, as well as adjacent to, an igneous body, usually a porphyritic stock. One deposit style includes both mineral dissemination and mineralized veinlets, and both porphyry copper and porphyry molybdenum deposits are characterized by dissemination and veinlet control of ore minerals. Those gold deposits that occur in stocks, with gold occur- ring in veinlets and disseminations within the stock, clearly are can- didates for consideration as porphyry gold type. Porphyry copper and porphyry molybdenum deposits are also characterized by potassic, phyllic, argillic, orpropyllitic alteration or some combination of these alteration types. Where two or more alteration zones are present, these are arranged in a sequential outcrop pattern. Gold occurring in dissemination and in veinlets in as well as adjacent to stocks, and which also occur in typical pervasive porphyry alteration suits, constitute a clearly defined class of deposit that fits the definition of a porphyry gold type. Porphyry copper deposits may carry appreciable gold. Porphyry copper-gold deposits are known from all porphyry copper provinces. This chapter is intended to cover porphyry gold occurrences that may have little or no copper or molybdenum as economic concentrations.

Jan 1, 1991

By G. A. Plakhin, A. V. Luganov, V. A. Luganov, G. V. Gorbatenko

In order to extract gold from the complex sulphur-arsenic bear­ing raw materials and to remove arsenic and sulphur from the process in an ecologically safe form we have studied oxidizing roasting of highly arsenic gold bearing concentrates with soda, leaching of cinders, processing of the obtained solution and extraction of gold from the cake. There were processed concen­trates containing from 5 to 28% of arsenic, 12-20% of sulphur in the form of pyrite and arsenopyrite. The content of gold in the concentrates was 4-75 git. The roasting temperature was changed in the range of 773-l 173K, the consumption of calcined soda was 75-200% of stoichiometric necessarily for bonding of arsenic and sulphur into the water soluble compounds, the dura­tion of the process was varied in the range of 10-120 minutes. Under roasting in optimal conditions up to 97% of arsenic and 95% of sulphur go into water soluble compounds. The out­put of cake is 65-70% of the concentrates. The extraction of gold from the cake is higher than from the raw concentrates. The technology has been tested on a pilot plant scale

Jan 1, 1996

By Henry E. Bakkila

Introduction United States Steel Corporation's, Texas Uranium Operations operates in-situ mines located approximately 70 miles north of Corpus Christi near the town of George West in Live Oak County, Texas. In 1977, Texas Uranium Operations became the operating entity for the Burns Ranch mines 100% United States Steel ownership and also operates the Clay West mines a 50150 joint venture of United States Steel Corporation and N M Uranium, Inc. Until mid-1982, Texas Uranium operated eight (8) satellites where uranium was captured on resin and two central plants where the loaded resin was eluted, acidized, precipitated and dried to yellowcake. At present, the Clay West Central Plant is operating, as are four (4) satellite plants in a mode designed to optimize results while depleting remaining reserves. United States Steel's Texas Uranium Operations, as have some other uranium producers, managed to continue successful production during the plunge to the recent floor price of $17. Despite the fact that United States Steel does not intend to continue as--a uranium producer beyond the life of its present reserves, we naturally hope the recent trend to the pre- sent price of $24 will continue to increase.

Jan 1, 1984

By Levent Ozdemir, Russell Miller, Fun-Den Wang

The full utilization of tunnel boring machines for excavation in medium hard and hard rock has been limited by insufficient knowledge of rock behavior under the action of mechanical cutters. An understanding of factors affecting the rock removal process will permit: (1) the more efficient design of tunneling machines, (2) the prediction of boring performance from geologic data and cores taken from the proposed tunnel alignment, and (3) an improved excavation rate, thus a lower tunneling cost.. The Colorado School of Mines, under the sponsorship of the National Science Foundation, is studying the effects of a number of parameters in regard to tunnel boring using both full and small scale laboratory tests, analyzing field boring performance and comparing the laboratory and field data. Results indicate: (1) the field boring performance can be reproduced in the laboratory, (2) the optimum spacing of cutters or optimum spacing to penetration ratios may be found in laboratory testing, (3) it is promising to use small core samples and laboratory testing to predict field machine performance and (4) effect of joints on boring rate is significant and should be included in predicting tunnel boreability.

Jan 1, 1974

By Jack E. Fraley, Robert E. Simpson

INTRODUCTION Spokane Mining Research Center (BuMines) is researching sealants for underground coal mines to: 1. Reduce sloughing of shale roofs. 2. Reduce sloughing of coal ribs. 3. Seal block stoppings against air losses. 4. Construct stoppings by spraying over jute cloth or metal lath. 5. Render incombustible in-place polyurethane foam. Originally the work was directed towards reducing sloughing of shale roofs. Many underground coal mines have shale directly over the coal which weathers severely after exposure to the mine atmosphere. Lab investigations(l, 2, 3, 4) have shown that many shales separate into layers when immersed in water or stored in a high relative humidity environment. Upon drying or after removal from high humidity, the shales continue to separate. Underground coal mines become wet in the warmer months from condensation of the ventilating air. Conversely, the mines become dry in the cooler months from evaporation. The mines experience severe shale break-up during the summer and much less break-up during the winter. Figs. 1, 2 and 3 show weathered shale roofs. in underground coal mines. Fig. 4 shows fallen shale on the entry floor. Sealing the shale reduces this sloughing problem.

Jan 1, 1974

By R. H. Seraphim

The name is derived from an Egyptian myth, "A beautiful lone bird which lived in the Arabian desert for 500 or 600 years and then consumed itself in fire, rising renewed from the ashes to start another long life." HISTORY This account of the first history is gleaned from old reports and documents which are listed in the Bibliography and from discussions with old-timers of the district. Prospectors were active in the vicinity of Greenwood in 189 1, and in that year staked the Mother Lode, Crown Silver, and Sunset. Henry White staked the Knob Hill claim in Phoenix on Jul. 15, 1891, and by the end of the year, other prospectors had staked most of the claims covering the valuable ore bodies in the camp. Much surface work done in the early years indicated that the values in copper, gold, and silver were low. Large capital investments were required to develop the ore bodies and build smelters. The discovery that the ore was practically self-fluxing greatly enhanced the value of the deposits. A map of the area showing the geology is given in Fig. 1. The bedded Brooklyn conglomerate is shown in Fig. 2.

Jan 1, 1991

By W. E. (Bill) Stanley

Introduction This is an exciting day. It isn't often that you can find the best minds in a particular business gathered together in one place. But that is what we have here. You are the best and the brightest people there are in the business of gold mining. What we discuss at this conference confirms the major issues facing us and sets out the issues governing how our mines and mining companies will be run in the next few years. In looking over the list of papers to be given, I have noticed something. It is something that I have noticed at almost every mining convention I have ever attended. Almost every paper at this conference concerns itself with the technical side of mining. Most of us in this roan are professionals; we are either engineers, geologists, accountants or representatives of some other profession. In getting where we are today, we have had to work hard to acquire the technical skills needed for our individual professions. We are all proud of our knowledge and work hard to claim the right to be considered an expert in a particular technical field or subject area.

Jan 1, 1987

By Stanislaw Nawrat, Waclaw Trutwin, Waclaw Dziurznski, Janusz Roszkowski

In recent years attempts have been made to fight open and intensive mine fires by the use of special extinguishers, which are able to produce great volumes of inert gases directed into the fire zone. These extinguishers are derived from turbo-jet engines used in aircrafts and adopted for operations in mine conditions. The purpose of this paper is to draw the attention to a computer simulation method, enabling studies of dynamical behaviour of mine ventilation processes disturbed by open fires, which are also influenced by measures taken during fire fighting actions i.a. the mentioned operating extinguishers. The first part of this paper gives an account of the principles on which the computer simulation program, concerning the non- steady mine ventilation process, the fire as a heat source and the extinguisher as a source of inert gas and moisture has been based. The next part of this paper deals with simplifying assumptions and the subsequent limitations of the derived simulation pro- gram. Finally, from an example of a computer simulation, the results will be presented and relations shown between parameters characterising the ventilation process during the fire fighting action.

Jan 1, 1997

By Hajime Miki, Michael J. Nicol

Relatively simple techniques have been developed which enable the electrochemistry of sulfide minerals to be studied with particles varying in size from above 100 pm to less than 1 pm. Both oxidative and reductive processes have been studied wing the minerals pyrite, arsenopyrite and chalcopyrite. It has been shown that it is possible to completely oxidise or reduce the minerals during a single voltammetic sweep. The resulting voltammogram produces peaks which are characteristic of each mineral and can be used to qualitatively identify the minerals. In the case of chalcopyrite, it has been demonstrated that the charge involved in the anodic oxidation can be quantitatively related to the amount of copper dissolved. Quantitative information can be obtained using peak fitting techniques. Interesting differences in the behaviour of the minerals in sulfuric and hydrochloric acids have been observed, particularly in the case of pyrite for which a second major peak is obtained which has been attributed to the oxidation of elemental sulfur in the presence of chloride ions. The technique offers the possibility of providing mineralogical information of individual particles based on an electrochemical voltammetic finger print.

Jan 1, 2005

By Kenneth F. Lane

In most industries it is normal commercial policy to try to gear production to the market. In times of scarcity output is pushed to its maximum and in times of glut output is reduced. Because of the effects of supply and demand, these times correspond to times of high and low prices respectively so the policy results in maximising long run total profits. Stockpiling is often an integral part of the policy. Stocks are accumulated during depressed market conditions and sold off when demand revives. This further increases the long run total profits. However, such policies cause violent fluctuations in short term profitability and impose severe financial strains. Indeed planning and implementing the policies are a central management concern which is often critical to the success of the industry. The mining industry is no exception and, for many raw materials, trying to balance supply with demand is an international problem. Stockpiling and restricted production agreements are common elements of policy. But very little attention has been paid to the one additional control which is unique to the mining industry, namely, the cut off grade. This neglect is apparent at all levels from individual mines to national economies.

Jan 1, 1979

By John D. Shaw

1. Introduction 2. The Hydraulic Mine _ (i ) Development (i i ) Extraction ( i i i ) Transport 3. The Water Circuit 4. Manpower and Results 5. Modifications 6. Conclusions 1. Introduction The Kaiser Resources Ltd. hydraulic coal mine is located in south eastern British Columbia, Canada, at the western end of the Crowsnest Pass, next to the Town of Sparwood. The seam presently being mined is the number 10, known locally as the Balmer seam, which is a high quality coking coal, 50 feet in thickness and of an average inclination of 35 degrees. The mine was designed in the late sixties as a small scale trial unit, and was to use a single monitor unit, working 3 shifts per day on a 5 day per week basis. Experience has proved the method to be so successful as to warrant the expansion of the ancilliary facilities to cater for the increased production. The annual raw coal production from this single monitor unit has risen from 108,988 short tons in 1970 to 942,334 short tons in 1975, with a total mine labour force of about 160 men including the surface de-watering plant, mine supervision and mine administration.

Jan 1, 1977

By L. Xu, S Jones, R. Bhaskar, J. McKenzie

The objective of this project was to optimize the ventilation parameters of a continuous miner underboom scrubber. This would result in further control of the amount of airborne dust discharged during mining, reduce the exposure of face personnel for an exhaust brattice ventilation system, and avoid recirculation of contaminants at the face. This research was performed in an underground coal mine in Utah. The tasks performed included preliminary face ventilation evaluation, and optimization of the scrubber system to eliminate recirculation of the scrubber discharge air. Airflow tests were conducted on the currently used dust control system and the modified scrubber system. Tracer gas tests were performed to evaluate face ventilation effectiveness. Confirmatory tests of the scrubber system under actual operating conditions, modifications to the scrubber system and a comparative evaluation of the scrubber system vs. the existing system were performed. This paper presents the results of the airflow pattern tests and the respirable dust levels in the modified scrubber system and the existing system. The optimized face ventilation parameters and the developed operating guidelines may provide the benefits of dust reduction, better lace ventilation and improved visibility.

Jan 1, 1994

By John Stroiazzo, Bernard C. Aubé

Brenda Mines, located 22 km Northwest of Peachland in British Columbia, Canada was an open pit copper- molybdenum mine which closed in 1990 after 20 years of operation. The primary concern in Brenda's tailings and waste rock drainage is molybdenum at a concentration of approximately 3 mg/L. The mine drainage is alkaline and contains little or none of the typically problematic heavy metals. Given that the waters downstream are used for municipal water supply and some irrigation, a discharge limit of 0.25 ma molybdenum was imposed with specific water quality guidelines in the receiving creek. A review of all existing and potential molybdenum removal methods was undertaken prior to mine closure. The chosen process is a two-step iron co-precipitation with clarification and sand filration at a slightly acidic pH. A 4,000 usgpm (912 m3/h) treatment plant was constructed and commissioned in 1998, at a cost of $10.5M. The successful removal of molybdenum from the drainage water is explained with details on some design innovations and operational challenges encountered during plant start-up. Investigated sludge disposal options are discussed although the long term disposal scenario has not yet been finalised.

Jan 1, 2000

By M. Yavuz

The use of natural stones like marble is approximately as old as the emergence of human. Marble and natural stone usage of Turkey also dates back to very old times. Marble is produced in Anatolia since the ancient times. The archaeological excavations made in Anatolia indicate that the modern methods that are used for the production of marble blocks in modern world were first used by Anatolian people. Turkey is one of the oldest natural stone producers with its 4000 years of production history, starting from the Marmara Island. Therefore, the territory of Turkey possesses 4000 years of natural stone processing technology and experience. Turkey has fairly richer reserves of marble compared to other countries. This is why the rich and quality marble deposits of Turkey are resembled to the appearance of the Alpine-Himalayan marble belt of the world. Turkey has almost 40% of the total marble reserves (13.9 billion tones) of the world with 5.2 billion tones. Turkey?s marble reserve?s monetary value is worth about 2 trillion dollars. However, only 1% of these reserves are currently being utilized.

Jan 1, 2011

By D. A. Rice, R. G. Swanton, A. May, O. C. Carter

As part of a cooperative effort between the US Bureau of Mines and the Florida Institute of Phosphate Research (FIPR), with input from the phosphate industry, the conversion of phosphogypsum to sulfur is being investigated. The proposed process incorporates a thermal reduction of phosphogypsum to calcium sulfide (CaS) and a hydrometallurgical treatment to convert calcium sulfide to ammonium bisulfide (NH4SH), which is then oxidized using a catalyst to produce elemental sulfur. The paper summarizes the results of continuing laboratory studies using an activated carbon catalyst which was loaded with sulfur through oxidation of ammonium bisulfide solution. The extraction of the sulfur that forms in situ on the catalyst is a key area in the development of the sulfur recovery process. Two approaches for removing the sulfur are being investigated: (1) thermal treatment to volatilize sulfur. and (2) leaching the sulfur using liquid anhydrous ammonia. The research has shown that it is technically feasible to recover over 90% of the sulfur from the carbon by either volatilization or ammonia leaching. Locked cycle testing has demonstrated that the carbon has the potential to be recycled after ammonia leaching.

Jan 1, 1987

By Charles L. Karr

Grinding is a necessary component in the processing of a number of minerals, and improvements in this area could provide substantial cost savings for the minerals industry. Optimizing the process of grinding, however, is a difficult task because there are multiple objectives; i.e., several aspects of the process are important including the fineness of the ground product, the energy consumed in the process, and the viscosity characteristics of the final slurry. Genetic algorithms (GAs) are search algorithms based on the mechanics of natural genetics and have been proven capable of solving multiple objective optimization problems. These robust search techniques are able to rapidly locate near-optimum solutions across a broad spectrum of very difficult optimization problems. In this paper, two varieties of GA are used to optimize a grinding process as it is described by a computer model: (1) a simple genetic algorithm (SGA) and (2) a micro genetic algorithm (MGA). The performance of these techniques is compared to the performance of a more conventional search technique, a simplex algorithm. Results indicate that the GAs are efficient, versatile, quite capable of improving the grinding process, and easily incorporated into the toolbox of today's process engineer.

Jan 1, 1993

By Marcel Haffen, Jean Janin

The purpose of grouting is to modify the permeability and strength characteristics of the subsoil in such a way that the planned structure can be efficiently constructed at a given location. This technique, which originally underwent considerable development in the field of dams construction is constantly evolving and it becomes more and more important in urban zones of intensive underground development for projects such as transport tunnels, stations, car parks, ect. Grouting becomes more and more indispensable whatever the natural characteristics of that subsoil ; such is the case particularly when the planned work runs through cohesionless granular soils, usually water-bearing such as alluvium, sands, disturbed ground, fill material, etc. The selection of the grouting method and the extent of treatment required at depends on two fundamental factors. 1º) nature and behaviour of subsoil to be treated. There is no need to stress the necessary of a good knowledge of geotechnical, hydrological and chemical characteristics of the ground to be treated. At the present time the specialists in these fields have available numerous methods of analysis, either laboratory or field tests, which enable to evolve a suitable treatment.

Jan 1, 1997

By A. E. Hall

INTRODUCTION Underground gold mining operations are found in South Africa, U.S.S.R., Canada, the United States, Zimbabwe, Ghana , Brazil. Australia, China and many other countries. The methods used for extraction differ from highly mechanized trackless mining in the developed countries to the labour intensive systems of the third world nations. The climatic conditions in which mines are situated vary from equatorial to arctic. The rock temperatures and the depth of workings also vary significantly from shallow to extreme depth. The Western Deep Levels mine in South Africa is the deepest and exceeds 4.000 metres in depth with strata temperatures above 55°C. These major differences between mining fields result in significantly different ventilation problems in underground gold mines. The ore types also vary and some deposits have high silica contents while other mines extract sulphide ores. Methane may also be encountered in underground gold mines and can have a large influence on the ventilation practice. Several topics are currently of concern to operating mines and are reviewed here:- a) Air circulation and fans b) Mine cooling c) Permafrost operations d) Mine heating e) Control of diesel exhaust f) Gases, fires and explosions

Jan 1, 1988

The visible portion of accounting-record keeping and preparation of financial statements-suggests a lack of sophistication and imagination. In reality, accounting is based on a large body of theory. Accountants philosophize, theorize, judge, create, and deliberate as a significant part of their professional practice. The subjective aspects that are so critical to current accounting practice, such as searching for truth and fact, judging what is fair presentation, and considering the behavior induced by presentations, are often overshadowed by the appearance of exactitude, precision, and objectivity that accompanies the use of numbers to express the financial results of the enterprise. * Fundamental accounting principles are hypothesized in the same manner as mathematical principles. These principles are justified by acceptability and intuition. Accounting theory is built upon these hypotheses, resulting in a coherent set of standards and rules. Although it does not specifically address every situation that may be encountered, this conceptual frame- work enables the manager or analyst to resolve specific situations. This framework also aids in the understanding and confidence in financial statements and ensures comparability between statements from different companies. This framework is referred to as "generally accepted accounting principles," or GAAP.

Jan 1, 1999