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By Joseph S. Malesky

The discovery and development of explosives mark one of the most important findings in the history of civilization. Without explosives our vast economic enterprise concerning the mining of coal, copper, iron, aluminum, and various other ores could not function. Explosives are used in all kinds of construction works, in the razing of old buildings, blasting of trenches, driving of tunnels, and in many other instances common to our everyday life. For these reasons explosives are rightfully referred to as the forerunner of progress. An explosive may be defined as a substance (usually a mixture) that, when flame or shock is applied, yields readily to rapid combustion or oxidation, accompanied by the formation of such relatively large quantities of gases as to produce much violence and pressure which, in turn, react against their surroundings and cause what is termed an explosion. By their very nature the action of explosives is destructive and disruptive of adjacent materials. Decomposition of explosives can occur through deflagration, which is rapid burning or combustion, as in the case of black powder, or through detonation, which is an almost instantaneous disruption, as in the case of dynamites and blasting agents.

Jan 1, 1981

By Gretchen K. Hoffman, George S. Austin

Soil amendments or soil conditioners generally carry the con- notation of being useful for problem soils or soils needing special treatments to produce maximum yields. Many different materials have been utilized, both inorganic and organic. Only the most commonly used and those that appear to have potential to become commonly used will be discussed. Soil productivity depends on many factors. Soil amendments mainly modify physical characteristics and microbial action, and/or change the pH of a soil, rather than directly supplying plant nutrients. They give soil the needed physical properties to allow plant growth, fight erosion, or save water. Some soil amendments provide nutrients in addition to altering the physical, biological, or chemical characteristics of soil. The term "soil amendment," as it is used by Soil Science Society of America, allows soil amendments to be materials other than those used primarily as fertilizers (Anon.,1987). Soil amendments as fertilizers of any type will not be considered here because this aspect is more relevant to the previous chapter entitled "Agricultural Materials: Fertilizers" in this volume. Several inorganic soil amendments have been used since the early 20th century to alter the character of soil: limestone, lime, and similar calcium-rich carbonates and oxides for acid soils, and calcium sulfate (gypsum) and native or uncombined sulfur for alkaline soils. The use of these amendments (limestone, lime, gypsum, and sulfur) or their equivalents has been studied and documented in many basic soils tests (McCaslin and Boyle, 1980). Perlite and vermiculite are considered in separate chapters and only a brief statement of their use as soil conditioners will be made in this chapter. Peat is the principal natural organic soil amendment, but manure, both as a fertilizer and soil conditioner, is used in every part of the world. In less-developed countries, manure is the primary soil fertilizerlconditioner. An organic-rich material designated as "humate" has been marketed as a soil amendment for many years and will be addressed in this paper. Other materials are discussed by the Soil Science Society of America in its Special Publication 7, "Soil Conditioners" (Stewart, 1975). They include bitumen emulsion, polyacrylamide, polyvinyl acetate, polyvinyl alcohol, bentonite, nonionic surfactants, and natural mulches. Zeolites can be added to the list of miscellaneous soil amendments (McCaslin and Boyle, 1980), as can calcium chloride (Pressler and Pelham, 1985), sulfuric acid, ferric and ferrous sulfate, aluminum sulfate, ammonium polysulfide, calcium polysulfide, and ammonium bisulfite (Stromberg and Tisdale, 1979). Sludge will not be considered as a soil amendment because it has properties more consistent with fertilizers. All these "other materials" account for a very small amount of the volume and value of soil amendments used and will be only briefly discussed.

Jan 1, 1994

By E. F. C. Ferrett

The benefits derived from the use of main fan evasees or diffusers are well known. If a well designed evasee is fitted to a fan either more air will flow through it or the same air flow rate will be discharged at a lower fan speed. This latter possibility will reduce the air power requirement of the mine, the fan input power and the overall energy costs. Despite these apparent advantages, many reports have been received from the industry of poor evasee performance. After examination, it appears that these problems are often caused by installation difficulties or inaccurate design procedures. The performance of an evasee is affected by several independent factors. Some of these factors describe the evasee geometry whilst others are concerned with the behaviour of the air as it passes through the evasee. This paper shows that the divergence angle is by no means the only ;important parameter which affects evasee performance and that the size of the inlet boundary layer has a significant influence. The performance of evasees of differing geometric shape are compared and the criterion to be used for optimum performance is discussed. It is shown that the commonly used evasee efficiency is a poor indicator of good performance. Recent work by the author and others is evaluated and a simple design. guide discussed. For more sophisticated work, details of a. computer program are provided. Finally, a brief resume of the performance of truncated diffusers is given. Since compressibility effects can be ignored for most mining applications, incompressible flow has been assumed for most of this paper.

Jan 1, 1980

By Robert S. Lehto

Zinc concentrates received in La Oroya zinc refinery are marmatitic in nature, contain about 11% iron and traces of other metal values, Figure 1 shows the zinc circuit. The calcine from the roasted concentrates is leached in spent zinc electrolyte. Major part of the impurities is iron which has been oxidized to its trivalent form, This is the origin of the zinc leach residue for which the ZILERET process was developed and so named. The impure liquor from the leach is sent for purification and thence to electrolysis- zinc deposits on aluminum cathodes from which: it is stripped, melted and cast into slabs Typical assays of zinc calcine and leach residue are given in Table 1. Metal values contained in the leach residue, without counting any value of iron, amount to roughly $130 per short ton.

Jan 1, 1969

By A. T. Weber, G. T. Adel

Earlier studies on the hydrodynamic interactions between fine particles and air bubbles have shown that fine particle flotation can be improved by using small air bubbles. In the present work, microbubbles ranging in size from 70 to 250 microns have been used in a flotation column for the processing of fine coal. The performance of the microbubble column has been studied as a function of wash water addition rate, aeration rate, feed rate and column length to diameter (L/D) ratio. The information collected from these tests has been used to analyze column behavior and to develop scale-up criteria. The results of this investigation suggest that mixing within the column may not be as significant as bubble size and residence time in determining column performance. Improved recovery can be obtained by decreasing bubble size which increases the flotation rate constant, and also by increasing L/D which increases residence time for a fixed column volume. The increase in residence time with L/D is due to a decrease in the volumetric flow rate of wash water with column diameter.

Jan 1, 1988

By Jessica M. Wempen, Dallan J. Coons, Bailey S. Simmons, Michael K. McCarter

Gate-road yield pillars are subject to increases in stress as the longwall face advances toward the pillars. Increases in pillar stress can be inferred by measuring roof/floor convergence surrounding the pillar. This paper presents a case study of convergence measurements surrounding a two-entry gate-road yield pillar in the head gate of a coal mine. Convergence was measured over a six-month period, as the longwall face approached and passed the pillar. Measurements were collected at eight locations surrounding the pillar: four locations in the travelway and four locations in the beltway. In addition to convergence stations, the pillar was instrumented with an array of seismometers. In future analysis, convergence measurements will be compared to seismic interpretations. This study reports on the geology and geometry of the longwall panel, the roof and rib support, the change in convergence over time, and the physical properties of coal and parting. Additionally, the convergence measurements are compared to pillar safety factor distributions derived from a finite element model. The convergence measurements contribute to the knowledge of when yield pillar abutment loading, caused by the encroaching longwall, is first detected. Knowing when abutment loading begins to yield the pillars can help define when standing secondary roof supports are required for head gate entry support.

By E. Topuz

The objective of mine ventilation is to provide suitable environmental conditions in working places at an economical cost. Maintaining a stable air flow, i.e., a flow quantity and the direction, is of vital importance. In practice, however, air flow quantity in underground openings varies continuously. Therefore, the stability of air flow means relative stability that is the flow in a branch moves along a certain direction while the variation in air quantity stays within acceptable limits. Many underground mines have low stability of mine air flow because almost all types of ventilation systems involve complex diagonal branches through which air flow quantity and, more importantly, the air flow direction may change easily. This creates extremely hazardous, unstable conditions, especially during emergencies. This paper deals with the directional stability of air flows in underground mines in single or multiple fan systems. It examines the rules of directional changes of air flows in diagonal branches, and proposes a method of calculating the stability conditions. It provides a criterion that may be used in designing new mine ventilation systems to ensure a desired degree of stability or in improving the existing systems.

Jan 1, 1986

By Kim Lapakko

As part of a project funded by the US EPA, through the Western Governors' Association, the recent literature on the prediction of acid drainage from metal mine wastes was reviewed. Static tests such as Acid Base Accounting, Modified Acid Base Accounting, B. C. Research Initial Test, and APP:S Test attempt to quantify the total capacities for a mine waste to produce and consume acid. In kinetic tests (e.g. humidity cells, soxhlet extraction, elevated temperature oxidation, column tests, batch reactor tests, B. C. Research Confirmation Test) mine waste samples are subjected to oxidation and the resultant drainage pH is assumed to reflect that of mine wastes dissolving in the field. This paper summarizes information presented in the recent literature on static tests.

Jan 1, 1992

By Rainer Kahrger, Guenter Ewald

The topic of this paper is to demonstrate the development of mobile crushing installations from throughput capacities of 200 tons per hour, to mobile and semi-mobile large- scale crushing installations with throughput capacities of 3,500 up to 10,000 tons per hour. Basis are approximately 140 mobile and semi-mobile crushing installations which have been built since 1956 or were on order in 1987. [FIGURE 1. Total Number of Mobile or Semi-mobile Crushing Plants] Sixteen of these approximate 140 mobile and semi-mobile crushing installations have a throughput higher than 3,500 metric tons per hour. Mobile crushers were developed more than 25 years ago in Europe for the quarry industry, which had special requirements - fairly low capacity, mostly softer and less abrasive material (limestone) and full mobility. So the majority of the units up to about 1980 were fully mobile, having a fairly small capacity and utilizing mainly hammermills, double roll and impact crushers. It was only when the mining industry and large quarries picked up the concept in the early 1980's that a drastic increase in capacity took place. Even though the first mobile crusher in a true mining application went into service in 1971, it took another 10 years before it proceeded in a larger scale. This trend was obviously supported by the drastic fuel price and energy cost increase in the mid 70's. Since the cost of conveying material is substantially cheaper than trucking it, the increase in energy cost, combined with increasing haulage distances provided a strong incentive. Figure 1 shows clearly the throughput distribution of all crushing installations and it also shows the sharp increase in the throughput capacities within the last few years.

Jan 1, 1989

By Richard H. Olson

The following discussion will deal with the domestic talc industry only, inasmuch as the writer has had no experience in this field outside of the U. S. This is strictly a geological-mining approach; no attempt is made to assess in depth the effects which milling technology and marketing capability might have in determining the potential of any given talc deposit.

Jan 1, 1970

By Sergio Estebanez, Martha Gross, Ruben Rubal, Yvonnick Rescamps, Alexandre Cochennec

The Hampton Roads Bridge-Tunnel (HRBT) Expansion project in coastal Virginia, USA will add two 1.5-mile (2.4 km) TBM bored tunnels alongside two existing immersed-tube tunnels between artificial islands. The site’s unusual constraints and the requirements of a large-diameter variable-density TBM shaped the design-builder’s decisions for handling TBM inputs and outputs, siting the TBM plant and supporting equipment, and sequencing tunnel-construction operations. This paper addresses the logistics necessary to enable key functions of the 46-ft (14-m) TBM and its ancillary equipment, including transport of most materials by barge, U-turn of the TBM on an artificial island, and delivery of materials for the second tunnel through the first one while interior structures are under construction.

Jun 13, 2021

By J. Pereyra, M. DeMarco

"INTRODUCTION It can be vital that bolted joints holding subassemblies together remain secure. Bolts should resist the loosening effects of vibrations and dynamic loads yet need to be easily removable during maintenance. When a threaded fastener is subjected to vibration, the rapid movement causes a lowering of friction against the threads and a subsequent loss of preload. The loss of preload allows the fastener to vibrate loose and possibly fall out. As the diameter of fasteners increase desired preload becomes increasingly more difficult to achieve. Input torque requirements for achieving proper bolt preload is exponentially related to any given fasteners diameter. This means that specialized tooling or bolting practices are usually required to attempt the tightening of fasteners to reach their required preload. Traditional methods can cause problems with joint integrity and do not provide consistent bolt load across the bolted surface. BOLTED CONNECTIONS A failed critical bolted joint can lead to high maintenance costs, machine downtime, and risk to worker safety. Control of the clamp load in a bolted joint is vital. However, when faced with a problem joint, it is not surprising that the design engineer will not have an answer if asked about the clamp load. Torque calculations must always be based on the existing conditions that often are vague. Unless all parameters are correct, the calculation will be unreliable. Examples of parameters are: • Thread condition of the fasteners • Hardness of contact surface • Material (steel, aluminium, copper, etc.) • Extra friction from a locking fastener • Extra friction from an adhesive • Lubricant on the thread • Type of bolt head (flanged, regular or serrated) • Surface coating of the bolt • New or reused fastener During tightening, bolts are subjected to both tensile and torsional stress. The total stress in a bolt can be calculated using the formula: Total stress = vsx2 + 3txy2 In order to maximize the desired tensile stress (sx) it is vital to minimize the torsional stress (txy). Tensile stress (clamp load) is achieved when the bolt is axially elongated. Unwanted torsional stress (twisting) in bolts arises during tightening due to thread friction. High thread friction increases torsional stress and causes yielding at lower clamp load levels than normal. A lubricant is necessary to minimize the malign torsional stress. However, many commonly used bolt-locking systems are based on increased thread friction (deformed nuts, adhesives, etc). To minimize thread friction and concurrently safely secure the joint has often incorrectly been considered impossible. The use of locking systems that increase thread friction is the single most common reason why the full capacity of bolted joints is not utilized. The following example illustrates the problem."

Jan 1, 2015

By S. S. Hsieh

As part of a program to address the long-term need to ensure adequate supplies of domestic phosphate raw materials, the Tennessee Valley Authority (TVA) has conducted considerable research on dolomitic phosphate rock beneficiation. The discovery that alkyl diphosphonic acids act as phosphate mineral depressants led to the development of several processes involving a carbonate flotation step for the effective beneficiation of these problem ores. Most recently, a partial deoiling process in which the reagent consumption is greatly reduced has been developed. The reduction is achieved because part of the initial feed is beneficiated without passing through the separate carbonate flotation step. Using this method, a phosphate product containing 30.6-30.9% P2O5 and 0.7-0.8% MgO was obtained from a Florida dolomitic phosphate pebble that contained about 23% P2O5 and 2.0% MgO. The P205 recovery was 80.8-86.5%.

Jan 1, 1991

By L. J. Laughlin

The majority of non-drive conveyor pulleys use rotating shafts, and typical idler rolls use non-rotating shafts, even though both products are used to support and guide the conveyor belt and its load. This paper will explore and compare the requirements for rotating and non-rotating shaft designs and the impact of that design on the product. Additionally, it will explore how the “roller” bearing types (deep groove ball, tapered, or spherical) affect these designs.

Jan 1, 2003

By K. R. Weller, U. J. Sterns, P. S. B. Stewart

Complex sulphide ores usually require very fine grinding of the whole ore stream to achieve adequate liberation. Recent improvements to DSM screens have made this device appear competitive with cyclones in circuits treating these ores. A DSM screen and cyclones were tested in pilot-scale grinding of a copper, lead, zinc ore and the resultant data were used to establish a multi-component simulation model. The model was used to assess the influences of mill environment, circuit flows and pulp densities, final product properties (size, relative size and SG of the values, and liberation characteristics) and a second grinding circuit on capacity and product size distributions, and hence define conditions for which one device is better than the other.

Jan 1, 1992

By Derek J. McCracken, William G. Holroyd

Emery is a rock that at one time held a large share of the abrasives market. The introduction of synthetic abrasives, however has forced it to settle for only certain niches in the marketplace. This loss of market share is due mainly to the higher amounts of impurities and weaker internal structure that naturally occurring minerals have compared to manmade materials. The use of rocks and minerals as abrasives dates back to early man, who used flint, quartz, and other natural materials to fabricate various tools. During the 19th century, with the Industrial Revolution imminent, the character of the abrasives industry was changed forever as synthetics were introduced. Frank B. Norton is credited with producing the first manmade abrasive when, in 1855, he manufactured a vitrified grinding wheel using emery grit and clay. Before Norton's accomplishment emery had been the only commercially available abrasive. The latter part of the 20th century has seen synthetics capture an increasing share of the abrasives market from natural materials. The term emery is believed to have been derived from the words emeri (French), smeriglio (Italian), and smiris (Greek). The term corundum, for the principal mineral of emery, seems to have originated from kauruntaka, the Indian name for the mineral. GEOLOGY Emery is a gray to black, granular rock comprised of various minerals including corundum (A1,0,), an iron-bearing mineral (usually magnetite-Fe,O,, hematite-Fe,O,, or hercynite- FeAI,O,), and several trace impurities such as mullite, titania, silica, and magnesia. The hardness of emery normally ranges between 7 and 9 on the Mohs scale, depending on its mineral com- position and level of impurities. Corundum, the hardest mineral in emery, typically has a hardness of 9. The specific gravity of emery ranges from 3.2 to 4.5, also depending on mineral composition and purity. The crystallography of each mineral contained in emery differs somewhat. Corundum exhibits an hexagonal crystal structure, whereas magnetite forms within the isometric system, frequently as octahedral crystals. Hercynite, an iron spinel, is also isometric. Hematite has an hexagonal structure but often is found as botryoidal and reniform masses. Principal deposits of commerical emery are found in the United States, Turkey, and Greece. In the United States two emery producers in the Westchester County-Peekskill area and one in the Cortlandt County area of New York closed their mines in the late 1980s. Commercial production in the United States now comes only from the western Cascade Range in Oregon. The emery in New York has a typical A1,0, content of 41.5%. Most of the rock is not true emery because it contains a mixture of spinel and magnetite but very little corundum. The deposits are of Late Ordovician-Early Silurian age and consist of veins in which emery is mixed with olivine, pyroxene, and hornblende. The veins evidently were formed by contact metamorphism and are surrounded by Precambrian schists that contain mica, sillimanite, cordierite, garnet, and quartz. The deposits in Oregon were formed during Miocene time by the contact metamorphism of ferrunginous bauxite by intrusive lamprophyric dikes and plugs. Emery is found in thin layers bordering these tabular dikes, which are usually oriented perpendicular to bedding, and in "surficial placer deposits. The emery deposits in Turkey occur as small, massive, lens- shaped bodies and as surficial placers. They are believed to have formed during Permian and Triassic times. In Greece the principal site of emery production is at Cape Emeri on the Island of Naxos. These deposits consist of lenticular masses of emery surrounded by marble. They originated during Mesozoic time, evidently by metasomatic replacement. Smaller deposits on several other Aegean islands were formed by the metamorphism of bauxite or other alumina-rich materials.

Jan 1, 1994

By Nawal Kishore, Nilesh Pratap Singh, Amit Kumar Verma, Vikram Seervi

In India, despite its natural abundance, demand for coal exceeds its countrywide supply due to failure to achieve high production targets, especially in opencast mines, which are responsible for 94.98 percent of total raw coal production in the country. Employment of technological solutions, such as surface miners, is key to achieving higher coal production and productivity in an environmentally friendly manner, especially in populated areas adjacent to the mining zone. This technology eliminates blast hole drilling, blasting and primary crushing units, thus reducing related environmental hazards like ground vibration and fly rocks.

May 1, 2023

By Erick F. Weiland, John W. Lindemann

Introduction Minerals exploration is one step in the mining industry's task of providing raw materials to basic industries. The industry's provision of raw materials involves identifying and evaluating resources, converting them to reserves, and intelligent, economic exploitation of these reserves. The mineral process focuses on identification and evaluation. Reserves are ore bodies and ore bodies are, by definition, wasting assets. Therefore, if an adequate provision of raw materials to basic industry is to continue, these wasting assets (ore bodies) must be replaced with new or different reserves as current reserves are depleted. Minerals exploration is a geologic problem and is fundamentally deductive, flowing from the general to the specific. Past exploration methods and philosophy have amply supplied the resources to meet the demands of an industrial society. During the past decade, however, the framework where mineral resources were identified, defined, and evaluated has changed. Mineral explorationists no longer can rely solely on the successful past methods to provide the necessary resources for our complex society. Productive explorationists must effectively and efficiently use tools and procedures that will maximize exploration efforts. Past tools need not be abandoned, but should be critically reviewed and revised in light of current scientific knowledge and technical advances. Future explorationists will view their craft not as a single discipline, but as a thoughtful integration of geophysics, geochemistry, and geostatistics for solving interrelated problems. This integration of the geosciences will lead to successful mineral exploration. Not only will the productive explorationist generate new information, he will master the use of existing data for identifying and evaluating a mineral resource. The mineral exploration process consists of incentives, ideas, finance, area, staff, time, and luck. The exploration process that stems from the interaction of these elements has three stages, each bound by a major decision point. They are selection, reconnaissance, and definition. Subsequent evaluation and exploitation phases are considered more the function of mining engineers than the exploration geologist. Mineral exploration endeavors that have been productive have three attributes fundamental to success: commitment, competence, and persistence. Commitment Commitment is believing that exploring for mineral resources is worth performing. While the mining industry is the focus of this commitment, government and society must also be committed to the concept of mineral reserve identification through exploration activity. Government demonstrates its commitment by providing access to land for exploration and, if it is successful, exploitation can take place. Realistic legislation relating to taxation, land use, reclamation, and environmental constraints is indicative of government commitment to intelligent resource use. The public must come to terms with mineral resource evaluation and extraction. Without some form of commitment from the public, availability of mineral resources vital to basic industry will be largely in the control of a foreign and potentially unstable mining industry. Commitment to a mineral resource identification-evaluation-extraction system must be shared equally by government, society, and the minerals industry. The scope and direction of this commitment varies, with the industry's commitment to explore for mineral resources being the most apparent. Industry commitment is the belief at all levels of exploration (from senior corporate executives to individual field and support staff) that exploration is worth performing, that exploration goals can be met, and that their particular organization is the best and the only group that can successfully accomplish the project. Commitment can be considered at three

Jan 11, 1983

By Lance Rasband, Richard Hanke, John Starcevich

"The world’s largest tunnel boring machine (TBM), at the time of her launch in 2012, the TBM locally referred to as “Bertha,” is incapacitated due to mechanical failure. Bertha’s stoppage places her 25m below the surface between the aged Alaskan Way Viaduct and the failing Seattle Seawall. Accessing Bertha with a vertical shaft provides the best approach to access all facets needed for repairs and will allow the full removal of Bertha’s cutter head and related inner workings. Due to the limited area above the tunnel alignment and physical constraints created by existing infrastructure, the dimensions of the otherwise symmetrical shaft are heavily impacted, thereby requiring special attention to design and layout. Consequently, the shaft design required a combination of 3m, 2.5m, 2.2m, 1.5m and 1m diameter unreinforced drilled secant piles coupled with various ground improvement techniques and dewatering, to fully satisfy the shoring design requirements. This paper will describe the shaft installation procedures, equipment used and pitfalls encountered while undertaking access shaft construction of this magnitude. INTRODUCTION Mining on Seattle’s SR99 tunnel began in July of 2013. Initial mining progressed slowly through a 4.5 m thick fiber-reinforced concrete headwall before immediately entering the first of three planned safe havens. Once through the headwall and safe haven the machine would move through roughly 122 lineal meters of jet grout improved soil at a rate of slightly over 1.6 m per day. It was anticipated that once mining has passed through the improved area, “Bertha” – now the world’s 2nd largest tunnel boring machine (TBM), would be moving at a rate of almost 11 m per day. By the end of October 2013, Bertha had mined roughly 131 m, averaging 1.4 m per day, and had begun mining within native soils. By the start of December 2013, tunneling had reached the 244 m mark and Bertha was now averaging 3.6 m per day, achieving as much as 12.8 m of progress on given days. Unfortunately, on December 6th, 2013, Bertha began to stumble and all progress quickly came to a halt. Initial reports stated an obstruction had stopped Bertha in her tracks. The preliminary investigation involved installation of 10 deep dewatering wells to reduce the hydrostatic pressure within the ground around the TBM, to allow the contractor’s personnel to inspect the cutter head from within and also to investigate for the presence of obstructions at the face of the cutter head. During inspection, the contractor’s crews found fragments of steel pipe entangled in the cutter head. The steel was apparently from an abandoned 254 mm diameter monitoring well casing, previously installed by WSDOT to monitor ground water conditions for the design and planning of this tunnel project. After the steel was removed from the cutter head and cleared from Bertha’s path, she attempted to move forward but was only able to generate a slow crawl."

Jan 1, 2016

By S. Bhagwat

Coals capable of emitting 2 lbs SO2/106 Btu heat input must be defined as high sulfur coals. This is because electric utility plants built after 1971 may not emit more than 1.2 lbs SO2, and those built before 1971, and regulated under the State Implementation Plans (SIP), may exceed the 2 lbs S0 limit only under closely defined restrictions concerning ambient air quality and prevention of air quality deterioration. Coals produced in Kentucky, Illinois, West Virginia, Ohio, Pennsylvania, and Indiana account for 77% of SO2 pollution potential and are, therefore, the subject of this investigation. These coals have suffered market share losses in the 10 years from 1974 through 1984. This is due to their sulfur content as well as their lack of price competitiveness with low sulfur western and imported coals. Kentucky and West Virginia have been able to increase their compliance quality coal production substantially, but other states have largely been unable to do so because of nonavailability of low sulfur coal deposits. Assuming that the current relative productivity and cost competitiveness of coal producing states will not change significantly by 1994, this paper makes two projections of coal production in the selected states. In scenario I, the current clean air regulations are assumed to apply until 1994, and coal production in the selected states is projected to in¬crease by about 6% in 1994 compared to 1984. In scenario II, it is assumed that acid rain legislation will be implemented, which will adversely affect the markets for high sulfur coals. Coal production in the selected states under this scenario is projected to decline about 10% between 1984 and 1994, jeopardizing up to 13,000 mining jobs. The author concludes that better coal quality and greater cost competitiveness are both essential to stem the market losses and to regain strength.

Jan 1, 1988