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By Evan Evans

WITH the expiration on April 30, 1941, of the agreement between the anthracite operators and the United Mine Workers of America, a new agreement was entered into, providing for a general wage increase of 7 1/2 per cent effective May 1, to be brought to a total of 10 per cent on Oct. 1. Contract rates were increased from the rates established under the agreement of September 1923, and hourly rates were raised above the agreement of May 1936 as modified from the eight-to seven-hour day in May 1937. The new rates are to be in force for the duration of the agreement, ending April 30, 1943.

Jan 1, 1942

By O. W. Borgeson, D. K. Honsberger, R. T. Bell

The Scully Mine, situated in the Labrador Trough near the Quebec-Labrador boundary, is one of the world's largest continuous ore deposits. This paper outlines the sequence of the mining operations from the planning stages to the delivery of the ore to the crusher at an average rate of 50,000 tons per day, 7 days per week. The principal equipment required to maintain this production rate includes four 12.\1.1-inch rotary drills, seven 8-cu.-yd electric shovels and a fleet of large haulage trucks. Particular attention is given to grade control, programmed by computer, drilling and blasting techniques and operational aspects inherent with open-pit mining in Canada's North.

Jan 1, 1969

By David J. Mack, Dennis R. O’Boyle

The mechanical properties of three polycrystalline intermediale Phases that have the y bvass structure were measured in compression between 400° and 900°K. At the lower testing temperatures— termed Region I— no plaslic deformalion occurred prior to brittle fracture. A1 higher temperatuves— lermed Region III—the three phases deformted plaslically for all strain rules from 1.5 to 36.0 x 10-4 sec-1. The homologous temperature for the inilialion of plaslic flow increased in the same order as tile atomic size difference between atoms in each plmse (0.50Tmp for y AgZn, 0.62Tmp for y CuZn, and 0.76 Tmp for y CuCd). The increased flow resistance oj. y CuCd above 0.50Tmp is explaitzed in terms of the more random arrangement of copper and cadmiwn atoms on the laltice sites of&apos; the y bvass slrilctlire. Plaslic deformation of the three intevmiediate phases in the smooth plaslic flow region appears to be controlled by oacancy-induced dislocation climb. RESULTS are reported in this paper on the mechanical properties of three binary intermediate phases having the complex cubic y brass structure (D82, 143m) containing fifty-two atoms in the unit cell. The structure of the prototype y brass phase, y CuZn, was first analyzed by Bradley and Thewlis&apos; based on the X-ray work of Westgren and Phragmen.2 The y brass structure can be visualized as an arrangement of twenty-seven body centered cubes (3 by 3 by 3) into a unit cell containing fifty-four atoms. From this cell the center atom and the four corner atoms are removed and the remaining fifty-two atoms are slightly displaced, resulting in the y brass structure. Approximately thirty-five binary intermediate phases that have an electron to atom ratio of 21:13 have been reported to form the y brass structure. The three y brass intermediate phases selected for this study are formed from elements in groups IB and IIB of the first and second long period. Each compound exists over a composition range that includes the stoi-chiometric composition A5BB (Cu5Zn8, Ag5Zn8, Cu5Cd8). y CuZn (a0 = 9.944A) has solubility limits extending from 57 to 67 at. pct Zn at 500°C apd melts peritecti-cally at 834°C; y AgZn (a0 = 9.326A) has a solubility range from 58 to 63 at. pct Za and melts peritectically at 661°C. y CuCd (a, = 9.596A) melts congruently at 563°C and has a maximum range of solubility extending from 58 to 64 at. pct Cd. In order to minimize coring and microporosity during solidification, the composi- tion of the compounds that form peritectically (y CuZn and y AgZn) was chosen so that the temperature difference between the liquidus and the solidus is only a few degrees centigrade. In selecting y brass compounds for this study, phases were avoided that contained a transition element or that had an electron to atom ratio greater than 1.70. Hume-Rothery et a1.3 has observed that, when the electron to atom ratio of y brass intermediate phases exceeds 1.70, atoms begin to drop out of the unit cell to maintain a constant electron to unit cell ratio. EXPERIMENTAL PROCEDURE Each of the three intermediate phases was prepared from elements having a purity >99.999 pct. Only trace quantities of impurities (<0.0001 pct) were detected by spectrographic analysis of the four elements. A master alloy of each compound weighing approximately 130 g was prepared by melting the elements in evacuated sealed quartz tubes heated in an electric furnace. Specimens having the desired diameter for the mechanical property measurements were obtained by remelting the master alloy in a Vycor tube under argon and drawing specimens from the melt into 4-mm-diam quartz tubes. To obtain a smooth surface on specimens drawn from the melt, the inside of the quartz tube was coated with a thin layer of graphite formed by thermally decompositing acetone. All specimens were imbedded in sealing wax and cut to the proper length with a diamond-impregnated cut-off wheel. The individual specimens (4 mm diam by 8 mm long) were then sealed in evacuated Pyrex tubes and homogenized at 500°C for 72 hr. Chemical composition, variations over the length of the rod (10 cm long) were generally less than 0.2 pct and the analyzed composition differed from the desired composition by less than 0.5 pct.4 Metallographic evaluation of the specimens after homogenization showed no evidence of a second phase in any of the compounds. The average grain size of the specimens after homogenization was 1 to 2 mm. All mechanical property measurements were carried out in an argon atmosphere using a compression apparatus described previously.5 Prior to applying the load to the specimen, the test apparatus was evacuated, back-filled with argon, and heated to the test temperature for 20 min to establish thermal equilibrium. EXPERIMENTAL RESULTS Mechanical properties measured as a function of temperature and strain rate for each of the three y brass phases were similar. From room temperature to the ductile-to-brittle transition temperature, only elastic deformation was observed prior to fracture.

Jan 1, 1968

By A. A. Tytko, T. S. Golosinski

"The paper discusses the accuracy of magnetic inspections of corroded hoist ropes. It quantifies the error of measured LMA (loss of metallic area) caused by presence in the rope of ferromagnetic products of corrosion. The paper concludes that in mining practice this error is not significant. Hoist Rope Corrosion and its AssessmentCorrosion is one of the most common forms of wire rope wear. For ropes working in wet mine shafts, ropes used by the fishing industry and, in general, ropes working in humid and chemically active environments, corrosion wear is usually the prime reason for rope discard. In most mining applications, rope corrosion is accompanied by fatigue cracking of wires, abrasion of external wires, internal nicking and other forms of wear.Quantification of corrosion damage in ropes using standard inspection procedures and examination methods is very difficult. Qualitative comparisons are sometimes used to describe the degree of rope corrosion to compensate for the lack of quantitative measures (SABS 0293, 1996). If available, the results of magnetic examinations of ropes may be of help in assessing their corrosion weakening.Magnetic rope examination requires that the rope first be magnetized. After that, the rope magnetic flux and the leakage flux along the rope are measured. The first is assumed to be directly proportional to rope metallic area (LMA) and its changes are indicative of the rope’s loss of breaking strength (LBS). Existence of the second indicates existence of local faults (LF) in the inspected rope. As the corrosion of rope results in development of corrosion cracks and in loss of rope metallic area, both the LF and the LMA should be used to quantify the level of rope corrosion. More specifically, the changes to the amplitude of the LF signal are considered to provide qualitative information on rope corrosion (Hansel et al., 1990), while those of the LMA signal are believed to provide quantitative information (Geller and Rousseau, 1990; Golosinski, 1996)."

Jan 1, 1999

By Peter Moser, Michael Hitch, Michael Tost, Susanne Feiel

"Impact and Benefit Agreements (IBAs) are intended to be a negotiated agreement between an industrial proponent and a community, local or regional citizens’ organization. Although the elements have grown over the past two decades from a simple agreement to exceedingly complex legal frameworks, the intention remains the same: to outline the roles and responsibilities of the two stakeholders and the natural resource development on their lands beyond environmental assessment. These agreements were born out of comprehensive indigenous land claims and have become the cornerstone of community engagement today in most indigenous nations. In the case of mixed communities, those that have beneficiaries of land claims and those who are not, social acceptance remains uneven and reflective of an unequal distribution of decision-making power (political ecology). This Differential Social License can cause conflict and a breakdown of the societal fabric that binds communities of diverse populations, resulting in inequality, fictitious wealth generation and failure of infrastructure. This paper presents a case study of how the development of Differential Social License developed in the Hamlet of Cambridge Bay, Nunavut as a result of an IBA negotiated between Tahera Diamond Corp. and the Kitikmeot Inuit Organisation in 2004 for the Jericho Diamond Mine.Introduction / Background Social license (social license to operate or SLO) has become an essential part of the social governance ‘toolkit’ demanded by mining stakeholders in today’s world. Stakeholders are now insistent that companies operate more closely under the tenets of sustainable development and provide for an increased level of community participation. Social license is not simply a matter of communicating with a community, to earn its consent for or acceptance of a project. It requires that we engage with the individuals and organisations who ally themselves with communities, or who sometimes side with dissident factions of a community. SLO is a process associated with and informed by political ecology or the recognition that unequal decision-making power exists amongst stakeholders."

Jan 1, 2017

By AUDLEY H. STOW

I. INTRODUCTION. THE general drift of the discussion as to the relative merits of pressure- and exhaust-fans has resulted, if we may judge from the prevailing practice, largely in favor of the latter. The subject has been hitherto treated, however, with special reference to highly gaseous mines, the effect of the form of ventilation upon dust-explosions having been too little considered. Even in mines containing practically no gas, dust-explosions may occur; and if, as I believe, pressure-fans are to be preferred for their effect upon dust, it may be worth while to reopen the debate, and to challenge the advisability of exhaust-ventilation under certain conditions. There are several forms of colliery-ventilation, which may be described as follows: Plain or simple pressure-ventilation, in which the fan acts as a pressure-fan, and the movement of coal is unobstructed at the surface by doors or equivalent devices in drifts or shafts, the traveling and haulage thus being in the return-current. Plain exhaust-ventilation, in which the fan acts as an exhaust-fan, the movement of coal being likewise unobstructed at the surface, and the traveling and haulage being in the intake. Obstructed pressure-ventilation, in which the movement of coal is obstructed at the surface, in order that the traveling and haulage may be in the intake. Obstructed exhaust-ventilation, in which the movement of coal is obstructed at the surface, in order that the traveling and haulage may be in the return. The apparent advantages in running a fan "pressure" during working-hours, and " exhaust" between shifts, seem to justify the recognition of this combination as a standard form of ven-

Feb 1, 1909

By J. A. Eisele

The Bureau of Mines is investigating the recovery of alumina from domestic nonbauxitic resources, including anorthosite. The United States has large reserves of anorthosite, but its aluminum content is less than 50 pct soluble in acid, unless a source of fluoride is added to the acid. A flowsheet that includes leaching with HCl and fluoride followed by crystallization of AlC13.6H20 from the pregnant liquor by HCl gas injection was designed. Approximately 90 pct of the aluminum values were recovered from the anorthosite when a ratio of 0.14 mole of fluorine per mole of aluminum was used. Sodium chloride is cocrystallized with the A1C13.6H20 but is removed by water washing of the Al203 product. A material balance is given based on results of laboratory studies of the unit operations.

Jan 1, 1983

By V. Sheikhzadeh, M. Saghaeian, R. Hejazi, A. Abazarpoor

"The morphology of pellet feed is known to influence several properties of iron ore pellets, including drop number, compression strength and reduction properties. The effect of grinding method on the particle size, specific surface area and particle shape of an iron ore concentrate has been studied. Grinding methods considered were ball mill and high pressure grinding rolls (HPGR). 5 different samples (Blaine= 1800, 1900, 2000, 2100 and 2200 cm2g-1) were used to compare the size, shape and specific surface of particles for each grinding methods. Particle size was meticulously examined by sieve analysis, laser sizing and image analysis. In samples ground by ball mill, it has been observed that the fraction of particles <10µm increases from 39% to 46% as the Blaine number increases from 1800 to 2200 cm2g-1. For HPGR samples, corresponding figures are 41% and 49% respectively. It is evident that for samples ground by HPGR, the fraction of fine particles is higher than that of those ground in the ball mill. To measure the specific surface area of particles, Blaine and BET were used. A higher real surface area was observed from HPGR treatment in comparison to ball mill grinding, provided by a higher porosity, cracks, roughness and new surfaces. Shape factor of particles was determined using three descriptors: circularity, roughness, and aspect ratio. It was also observed that particles produced by HPGR were more elongated, less circular, and rougher than those processed by the ball mill. 1. INTRODUCTION Particle size and shape are important parameters that can significantly affect mineral processing plants and pelletizing plant performances (Brozek and Surowiak, 2007). It has also been proposed that green pellet quality is directly related to the amount of fine particles in a pelletizing plant (Dwarapudi et al., 2008; Umadevi et al., 2008; Gul et al, 2014; Van der Meer, 2015). Particle size distribution and specific surface area (SSA) are also key factors that can control the quality of green and fired pellets. Processing circuits generally reduce the fines fraction to lower than the required specific surface area (SSA). It is therefore necessary to regrind concentrates to produce suitable pellet feed for further treatment in the balling and firing steps [1, 2]. Two main methods are used for re-grinding of concentrate; high pressure grinding rolls (HPGR) and ball mill. Given the different forces used to reduce size in these methods, it is expected the shape of particles will be different (Pourghahramani and Forssberg, 2005)."

Jan 1, 2018

By T. G. Joseph

The chicken and egg scenario where adverse truck motions cause ground deterioration and poor ground profiles that in turn cause adverse truck motions is a downward deterioration spiral that dominates in our industry. If we can remove one action, the reaction must stop and vice-versa. A simple &apos;truck to excavator&apos; load data analysis and wireless communication system is outlined in this paper; that will provide visual assistance to the excavator operator in achieving improved load placement and balance in a truck body. In turn this will reduce the subsequent hauler duty cycle adverse motions and g levels that contribute to structural fatigue, higher tkph, reduced tire life and ongoing maintenance of haul roads

Nov 1, 2011

By J. Drelich

An improved experimental procedure to measure contact angle has been consolidated with coal surface preparation involving polishing with abrasive paper, alumina powder, and a cloth, followed by ultrasonic and mechanical cleaning. Specifically, the captive-bubble measuring technique has been compared with the sessile-drop technique and the former has been recommended for the examination of the hydrophobic properties of coal surfaces. Results of the research program, which is currently under way, on the examination of the effect of the nature, amount, size and distribution of mineral inclusions in coal on its wettability are briefly reviewed.

Jan 1, 1999

By Alex Luyima, Jaan Kers, Lifeng Zhang

"The pyrolysis of PWBs was investigated by a TG-DTA-MS furnace at 300–1173 K. The kinetics and the control of emitted gas during the pyrolysis of PWBs with and without chemical additives were studied. Moreover, the possibility of controlling the amount of toxic exhaust gases like HBr, C6H6, Br2, Cl2, HCl gas and recovering beneficial gaseous fuels like CH4 and H2 from pyrolysis process is discussed. The MS data for each PWB sample were examined as a function of temperature and particular m/z values could be associated with the mass loss steps in the TG data. The degradation of the organic material was characterized by m/z = 2, 16, 18, 28, 36, 44, 71, 78, 81, and 160. Fe2O3 was the best inhibitor of toxic HBr and C6H6 when compared to Al2O3, CaO Y-zeolite and ZSM-5. Moreover, it had no significant effect on the valuable H2 and CH4 gas evolution. This selective inhibition of toxic gases while maintaining the valuable ones make Fe2O3 the best candidate among the investigated additives in controlling gas emissions from PWB pyrolysis process.IntroductionThe electronic and electric industry is one of the world’s largest and fastest growing manufacturing sectors. As a consequence of this growth, electrical and electronic waste (e-waste), such as computers, washing machines, printers, mobile phones, television sets, stereos, radios, etc., is generated in large quantities around the world. Printed wiring boards (PWBs) are a common component of many electronic and electric systems.[1]. The rapid development and expansion of the electronics industry over the past several decades have led to a dramatic increase in the production of PWBs and a corresponding increase in the amount of waste generated from both production and disposal. The environmental impacts of the treatment and recycling of PWBs waste have become a major concern [1-2]. PWBs are particularly problematic to recycle because of the heterogeneous mix of organic material, metals, and glass fiber [1]."

Jan 1, 2012

By George T. Faust

The petrographic microscope plays an important role in the mineral dressing of nonmetallic materials. Petrographers and mineral technologists have evinced an interest in the technique developed, specifically, for mineral-dressing problems. The following dissertation makes the informa¬tion more generally available. ACKNOWLEDGMENTS The authors are indebted to O. C. Ralston, chief engineer, Nonmetals Division, and to Will H. Coghill, supervising engineer of the Southern Experiment Station for a critical reading of the manuscript. They are also indebted to their colleagues for technical information obtained in the course of cooperative work, in particular to J. B. Clemmer for the use of the data on fluorite.

Jan 1, 1940

By J. F. Barkley

The work covered in this report was done to meet the requests from many Government agencies for information on alleviating sludge difficulties in No. 6 (Bunker C) fuel-oil storage tanks. Accumulated sludge at times caused serious loss in tank capacities; pumps became overloaded or lost suction; strainers often required very frequent cleaning; fuel-oil heaters in some instances became fouled and inefficient; and gobs of sludge that passed the strainers interfered with good combustion. The requests also included questions regarding the usefulness in general of oil "additives" for preventing sludge and the relative merits of the many trade-named additives being marketed. Realizing that preventing such difficulties would result in substantial savings to the Government, an investigation was begun with the limited funds avail-able. Although various claims are made for No. 6 fuel-oil additives other than preventing sludge, only an investigation as regards the storage tank-sludge problem has been possible.

Jan 1, 1955

By Dirk van Zyl

Natural materials can be used successfully in the construction of heap leach pads. The use of these materials usually result in the least expensive approach for such facilities. Sufficient geotechnical experience has been gained in the design and construction of clay heap leach pads so that they can be used with confidence. A number of operators presently use clay pads in their heap leach facilities; these include Alligator Ridge, Ely, Nevada (gold), and Union Carbide, Gas Hills, Wyoming (uranium). This paper describes the construction and field investigation of a clay pad for the heap leaching of agglomerated precious tailings. The project is located in the Mojave Desert, Southern California. The design had to satisfy operational requirements as well as regulatory requirements. The California Water Quality Control Board (WQCB) was one of the agencies which had to issue a permit for the project. Their biggest concern was the discharge or escape of cyanide into the environment. Rather stringent requirements were therefore placed on the pad design criteria, especially in terms of permeability.

Jan 1, 1983

By Thomas V. Falkie

The title of this talk has brought some interesting responses - even before it was written - from different parts of the country. A geologist from the Western U. S, was deeply concerned with recent layoffs in his profession and the employment situation in general and wondered why "the AIME wasn&apos;t doing anything for the benefit of its members." A petroleum engineer in Texas said that a group in his field were studying "professionalism" and their professional status and wondered if there were any words of wisdom for him. A mining engineering professor from the East pointed out that the National Science Foundation did not include mining engineering as one of its recognized fields in one of its equipment funding programs. These are just a few examples of reactions received to date, but they serve to illustrate the broad image that the title has meant to various people. Actually the term profession is defined by Webster as "a calling requiring specialized knowledge and often long and intensive academic preparation." The word encroach means "to enter by gradual steps or by stealth into the possessions or rights of another", or "to advance beyond desirable or normal limits." The intention of this paper, as originally conceived and requested by the program chairman, was to combine those two words literally and talk about how the professional standing of mineral engineers is being eroded from people outside the profession. But the amazing preliminary response suggests that it may be timely to broaden the discussion by including some comments about professionalism in general. In the paper the terms "mineral engineer" or "mining engineering" are used frequently, but it should be clearly understood that much of what is said is valid and is intended for all fields covered by SME and perhaps for AIME in general.

Jan 1, 1972

By Jean M. Kenney

Frequencies of haulage-related accidents in metal and nonmetal surface mines for the years 1988 through 1990 were investigated and compared with those of non-haulage-related accidents. This study was part of the U.S. Bureau of Mines program to improve mining haulage safety. Data were obtained through the U.S. Bureau of Mines Accident Data Analysis (ADA) program. The chi-square test was used to compare frequencies of haulage-related and non-haulage-related accidents for each of the following variables: degree of injury, age, total number of years of mining experience, and shift time. Significance was determined for degree of injury between haulage-related and non-haulage-related accidents. Age of injured did not vary significantly between haulage-related and non-haulage-related accidents, but total number of years of mining experience was found to be significant. Shift time for the accident proved to vary significantly between haulage-and non-haulage-related accidents. Events causing injury for haulage-related accidents were tabulated, and the most frequent determinants of haulage-related accidents were identified. Accident descriptions for both fatalities and permanent disabilities were studied, and the primary causes of these accidents were identified. These findings suggest that haulage-related jobs are among the most dangerous when considering accidents experienced by all workers in the metal and nonmetal surface mining work force.

Jan 1, 1993

This paper examines some of the important aspects of mineral taxation policies and practices, with reference to the mining tax regimes of selected Pacific Rim countries (see Tables 1 and 2). The following subjects are addressed:what is æmineral taxationÆ?, basis for mineral taxation, types of mineral taxes, objectives of the mineral taxation regime, best practices, and mineral royalties. Many countries, in some cases with the encouragement and assistance of international funding agencies, are actively assessing the international competitiveness of their mining tax regimes with a view to attracting investment. However, these countries recognise that the mining tax regime is not the only consideration that is taken into account by prospective investors. The countryÆs geological prospectivity, physical infrastructure, labour force, political risk, and regulatory system are also important factors in the investment decision making process. Although it is probably true that an attractive mining tax regime will not necessarily attract mineral investment, there is a real possibility that an unattractive regime can drive away investment. For example, Hugo Dummett, general manager for discovery at BHP, hinted recently that BHP could cease exploration in Russia in the absence of positive tax changes. Dummett is reported as saying that if taxes æend up being as onerous as they are now, we really have to rethink why we are hereÆ (Mining Journal, London, November 27, 1998).

Jan 1, 1999

By Jr. Goller

You and I can visit cement plants, inspect the various rotary kiln systems and find some equipment or some burning techniques that waste energy--fuel and power. After we have made such a visit and studied a few ideas, we could recommend ways to eliminate much of this waste. Probably every idea would cost money to bring into action. For our discussion, let us arbitrarily set an upper limit of $1,000,000 on the recommendations that we are allowed to make. Call these "low-cost" or "short-term" measures. They are improvements that do not require more than say, three months to complete; they do not require a major revision to the process. Other recommendations are "high-cost" or "long-term"; they are outside the scope of this discussion. Some of our "low-cost" recommendations would offer a satisfactory return on the money that they cost; the remainder would not. Now, is there some way that we can rather quickly pick out the "low-cost" measures that will show a satisfactory return and spend our time making these improvements first? Can we separate these items from those where the return is less likely to be good? I feel that we can pick some of these items quickly if we have a kiln system that has consistently non-uniform day-to-day operation. If the operation is uniform we probably cannot pick them quickly.

Jan 1, 1977

By P. G. Claridge, G. P. Holmes, M. A. Redfearn

"IntroductionThe purpose of this chapter is to describe current practices in operation and maintenance of flotation circuits in Canadian mineral processing plants. The chapter consists of five sections covering description of equipment, typical flow diagrams, operating practice, instrumentation and maintenance. The approach to this subject matter is intended to be practical in nature, hence no deeply technical treatment of flotation theory will be included.Flotation is an extremely common method of beneficiation of ores. Reasons are the relatively low cost of flotation compared to many other processes, the wide range of minerals to which flotation may be applied and the high efficiency of separation which can usually be achieved. The flotation process as we know it today has been developed within this century and it has had a major impact on the mining industry. While flotation is commonly considered to be important because it provides a relatively simple method of separating minerals in complex ores, the availability of flotation has also made a multitude of mineral deposits in Canada into economically viable mining operations because it allowed production of a concentrate of valuable minerals from the ore. These concentrates could then be transported from geographically remote locations to centraHzed plants for further processing, although the existence of the remote and perhaps small ore body alone would not have justified installation of metallurgical processing plants on site and the grade of ore would not have justified direct shipment of ore.Some of the more common minerals concentrated by flotation are sulphides of copper, nickel, cobalt, iron, zinc, molybdenum, lead and arsenic, as well as non-sulphides such as sodium chloride, potassium chloride, phosphates, silicates, chromite, fluorite, limestone and coal. Precious metals are also recovered by flotation, generally in association with another sulphide mineral."

Jan 1, 1989

By Thomas M. Barczak

This U.S. Bureau of Mines report examines the causes and consequences of longwall face sloughage. Theoretical relationships were developed to evaluate mechanisms that produce slough age. From these relationships, contributory factors were identified for further analysis in field efforts. A survey identified 12 mine sites with sloughage problems, and these were investigated. From these studies, it was determined that the depth of cover and mining height are the two most significant factors causing sloughage on longwall faces. Coalbed friability and cleat orientation also were found to be significant factors in promoting sloughage. It was concluded that sloughage is primarily a problem in thicker seams or seams with friable coalbeds, and that the problem is more severe as the depth of cover increases. Sloughage also was found to increase as the rate of mining decreased. Observations indicated that face slough age can increase dust generation significantly on longwall faces. Current efforts to control dust generation from longwall sloughage are described.

Jan 1, 2010