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By Halagowder Devaraj, Mostafa Sheykhnazari, Veer P. Bhavanandan

"A sensitive colorimetric assay for detecting mucins and glycoproteins rich in 0-glycosidically linked saccharides is reported. The method combines the susceptibility of N-acetylgalactosamine terminating 0-glyco idically linked saccharides to P-elimination with the Morgan-Elson reaction for N-acetylhexosamines with free reducing ends. All mucin and mucin-type glycoproteins but none of the serum-type glycoproteins tested resulted in characteristic color production. All mucins tested gave linear responses in the range 5 to 200 ""g and the assay was also adapted to the microscale involving the use of 96-well microtiter plates. The microassay in which the volumes of samples and reagents are scaled down 2.5-fold was particularly useful in monitoring of mucins, in the presence of other glycoconjugates, in large numbers of samples obtained during fractionation procedures. Cesium chloride, cesium bromide, potassium thiocyanate, and various detergents do not interfere with the colorimetric determination. Guanidine hydrochloride, cesium triftuoroacetate, and B-mercap- . toethanol decreased color by 30 to 45%; however, the interference was not serious to prevent the use of the method for detection of mucins in their presence. The use of the method for the specific detection of mucin during fractionation by gel filtration and density gradient centrifugation of cystic fibrosis sputum samples is demonstrated. Mucins are an important class of biomacromolecules whose structure-function relationship is poorly understood (1,2). The investigations of mucins are hampered by difficulties in purifying these very large size molecules which appear to avidly bind other components of the mucus (3,4). One of the problems during purification is the specific detection of mucins. For example, during the various purification steps, the fractions containing mucins are typically detected by assaying for neutral sugars (hexoses) (5,6), for sialic acids (7), or for periodate oxidizable saccharide units (8). However, these methods are not entirely satisfactory because neutral sugars, sialic acids, and periodate-oxidizable saccharides are also components of other glycoconjugates. In addition, the neutral sugar and sialic acid measurements are also subject to interference from high levels of proteins and nucleic acids."

Jan 1, 1990

By R. Hogg, T. F. Dumm, L. G. Austin, M. Yekeler

"Dedicated to Professor Kurt Leschonski on the occasion of his 60th birthdayAbstractThe kinetics of batch grinding quartz from a feed of 600 by 425 Jim to a product of 80% less than 10 µm have been determined using screening and laser diffractometer sizing for size analysis. The specific rates of breakage decreased by a factor of about three when the material became less than about 100 µm in size, but the primary breakage distribution function also changed to give proponionately more fine material, so that the grinding efficiency expressed as the development of surface area (B.E:T.) per unit of energy input did not decrease. Analysis of the shape of the particles in the 2S x 38 µm size range showed that particles of this size produced by roll crushing or by 8 minutes of grinding of a 42S x 600 µm feed were not different but at long grinding times the particles were rounded. This suggests that the breakage mechanism changes to give more chipping and abrasion and less disintegrative fracture. As the material approached the ultrafine size range it adhered to the mill case and there was no further size reduction. However, a technique for striking the mill case to dislodge the particles was successful in allowing further grinding to 400Jo by weight less than 2 µm.1 IntroductionIt has long been known that it is difficult to accomplish ultrafme grinding in a tumbling ball mill. It has been reported [12, 13] that there is no further size reduction after some hours of grinding cement clinker in laboratory ball mills. Austin and Bagga (1] and Shah and Austin [16] have given an analysis of the kinetics of dry grinding in a laboratory ball mill, introducing the concept of a slowing-down factor K, which is the ratio of the specific rates of breakage at some long time of grinding to the normal specific rates of breakage. They showed that this factor decreased as fine material accumulated in the mill charge. Cottaar and co-workers [8-10] showed that the movement of solid in a dry laboratory ball mill was influenced by the fineness of the solid and by the presence of air, and that evacuation of air from the mill caused particle sedimentation and low rates of breakage.The concept of the slowing-down factor has also been used in wet grinding [17, 18]. At very .high slurry concentrations it appears to be correlated with a steady decrease of mill power caused by the build up of a layer of deposit sticking to the mill case. This reduces the effective mill diameter and, eventually, the balls start to adhere in the layer and centrifuge. A decrease of mill power always indicates less lifting and tumbling of the media and, hence, less breakage. However, slowing-down of breakage rates was also observed at lower slurry concentrations where there was no change in mill power."

Jan 1, 1990

By D. E. Pollock, Andrew B. Cecala

It has long been known that ventilation is a cost-effective method to lower respirable dust concentrations in all types of mining applications. The National Institute for Occupational Safety and Health has been working on a number of different research techniques that use ventilation as a critical component to lower respirable dust levels at surface and metal/nonmetal operations in the United States. This article presents five such research efforts. The first research area discusses how improving the ventilation flow patterns in an iron ore mill facility lowered respirable dust concentrations by 31 pct throughout the primary grinding area. The second research area examines how respirable dust levels were lowered at a dimensional stone shop by using air cleaning units suspended from the ceiling. A third area discusses how improvements in ventilation at underground limestone mines lowered respirable dust concentrations. The fourth area examines how improvements in dust filtration and pressurization systems significantly impacted the air quality in enclosed cabs of surface mining equipment. The last area presents a newly developed clothes cleaning technique. This technique uses an air spray manifold to blow dust from a worker’s clothing in an enclosed booth, which confines the dust for capture and removal by a baghouse dust collector. These research areas represent an array of different control technologies to lower respirable dust concentrations. Ventilation is an integral part of these control technologies.

By A. S. Moore

The Bureau of Mines is doing research and development work on removing acid-gas impurities from synthesis gas made directly from coal. Since conventional gas scrubbers, packed towers and bubble-cap columns, are expensive to construct and difficult to operate with viscous solutions, one aspect of the work was developing a compact, agitated, gas-liquid contactor for use with concentrated absorbents. The efficacy of the agitated contactor for absorbing carbon dioxide in diethanolamine increased with increasing solution rate, turbine speed, diethanolamine concentration, and carbon dioxide concentration in feed gas, and with decreasing liquid-gas ratio. It was unaffected by pressure between 200 and 300 p.s.i.g. and little affected by temperature between 115 and 190° F.

Jan 1, 1961

By Sheridan J. Rodgers

Toxic fumes generated during shot firing under actual mining conditions were measured. Eight shots with Gelodyn-2X and seven shots with Tovex-100 4VT were monitored. Average CO values for Gelodyn-2X and Tovex-100 4VT were 0.20 ft3/lb and 0.09 ft3/lb, respectively. Average N0x values for Gelodyn-2X and Tovex-100 4VT were 0.049 ft3/lb and 0.026 ft3/lb, respectively. The results obtained with these in-mine tests will be used by the U.S. Bureau of Mines in the development of a large chamber method of measuring fumes from shotfiring of explosives.

Jan 1, 1977

This chapter presents data on occupational exposures from several sources. Data from compliance samples obtained by MSHA inspectors are presented in table 6-1 for coal mine dust and silica dust, and in tables 6-2 through 6-6 for metal fumes. Since these samples were taken for compliance monitoring rather than as part of a survey of the industry, it is difficult to predict how well they indicate actual exposures for all mining operations. In the coal industry, 7.8% of all respirable dust samples during 1986-1995 were above the permissible exposure limit (PEL). Of silica dust samples obtained during the 10-year period, 23.7% were above the PEL in coal, 16% in metal, 10.8% in nonmetal, 9.1% in stone, and 7.6% in sand and gravel. Of metal fume samples, silver samples showed the largest percentage above the PEL-approximately 48% of samples in both metal and nonmetal. Tables 6-7 and 6-8 present data on noise exposures from the MSHA "dual threshold" survey, which was published in the Federal Register [61 Fed. Reg. 66347 (1996)] as part of a proposed rule change for occupational noise exposure in mining. This study examined a group of samples obtained during 1991-1995 and compared the percent of samples that were above two separate specified limits. The first limit was the current noise standard, a time-weighted average of 90 dBA, calculated to include only exposures at 90 dBA and above. The second limit was a time-weighted average of 85 dBA, calculated to include exposures at 80 dBA and above. Tables 6-8 and 6-9 refer to musculoskeletal overload conditions examined in the National Occupational Health Survey of Mining (NOHSM) [NIOSH 1996]. Table 6-8 shows the operational definitions for each condition; table 6-9 shows the percentage of the workforce potentially exposed, by commodity. Across all commodities, a large proportion of workers were exposed to musculoskeletal overloads due to positioning of the neck and back; positioning and motion of the forearms, arms, and shoulders; heavy lifting; and positioning and movement of the lower limbs. The recorded overloads were defined in the survey and did not exceed any NIOSH, MSHA, or OSHA guidelines for musculoskeletal overloads. Further information on this survey appears in appendix A.

Jan 5, 2000

By Robert A. Elgin

The Leadville mining-district (fig. 1) covers approximately 8 square miles adjacent to Leadville, the county seat of Lake County, Colo. It is famous for its large production of rich ores containing zinc, lead, copper, gold, and silver. Some manganiferous ores also have been produced.

Jan 1, 1949

By Harold P. Rue

The problem of removing hydrogen sulphide from natural gas has become within the last few years one of major importance to the natural gas and petroleum industry. Several gas fields in the United States produce natural gas containing hydrogen sulphide, and a number of oil fields produce gas which contains hydrogen sulphide. 3 The percentage of hydrogen sulphide in natural gas produced in these fields varies from a fraction of 1 per cent t6 as high as 20.5 per cent by volume. 4 Hydrogen sulphide is probably the most toxic gas associated with natural gas,5 and from the standpoint of health and safety it is important that the hydrogen sulphide be removed if the gas is to be used for domestic purposes. Hydrogen sulphide, besides being toxic and therefore a hazard to animal life, is under certain conditions an active corrosive agent and very destructive to equipment. 6 The annual loss caused by the corrosive action of hydrogen sulphide on equipment amounts to hundreds of thousands, perhaps millions, of dollars. 7 The largest percentage of natural gas produced in the United States comes from wells which also produce oil. This associated gas invariably carries with it light fractions of petroleum, which when separated from the gas, condense to the liquid form at ordinary temperatures and pressure. Commercial application is made of this natural condition, and "wet gas" is processed to obtain so-called natural gasoline by employing the principles of absorption, adsorption, or compression and subsequent expansion accompanied by cooling. In the manufacture of natural gasoline from wet gas which contains hydrogen sulphide, if this contaminating gas is not first removed, some of the hydrogen sulphide may oxidize to form free

Jan 1, 1932

By F. E. Cash

"Explosions in bituminous coal mines are preventable. The combination of adequate ventilation, thorough rock-dusting, and water on the cutter bars of mining machines and of empty and loaded cars will certainly reduce the hazard to a minimum, if not remove it entirely. This is the attitude taken by the Woodward Iron Co. in lessening or removing the dust and gas explosion hazard from its Dolomite and Mulga mines.This report was made possible through the willingness of Frank H. Crockard, president of the Woodward Iron Co. to make records available and to authorize their publication for the benefit of the coal-mining industry.The compilation of these data and preparation of maps was facilitated by the cooperation of M. Heard, general superintendent of coal mines, J. B. Whatley, assistant general super-intendent of coal, and R. P. Whetmore, chief mining engineer.The Dolomite and Mulga mines are about 16 miles southwest of Birmingham, Jefferson County, Ala., on a company owned and operated railroad which connects ore mines, coal mines, coke ovens, and furnaces.In the Dolomite property there is a 30°, 860-foot, double-tracked slope for hoisting, three manway and air slopes and one air shaft, all in rock.At Mulga there is a 220-foot hoisting shaft, an air shaft and two manways, and material and air slopes, all in rock to the coal bed.The coal in both mines comes from the Pratt bed, which is the next coal above the Mary Lee bed in the Warrior Basin. The coal is horizontal or slightly undulating, with thickness varying from 36 to 72 inches and averaging 50 inches.The method of mining is essentially room-and-pillar with modifications for mechanized sections. The mines produced approximately 1,100,000 tons with 2,328,309 man-hours exposure n 1929 and 900,000 tons with 1,697,436 man-hours exposure in 1930.Through the work of the safety department the entire personnel in the coal mines, as well as in other departments, makes safety an essential part of efficient operation.Both mines are gassy; Dolomite produces about 334,000 cubic feet and Mulga about 919,000 cubic feet of methane every 24 hours.The ventilation maps, two of Dolomite mines (figs. 1 and 2) and one of Mulga (fig. 3) give as much of the details of ventilation as is practicable to put on maps of such scale. As will be seen from these maps there are two main ventilating fans in Dolomite mine and two in Mulga mine and the general direction of the air travel is indicated by long arrows to fan 1 and short arrows to fan 2 in each mine. Each fan has a gas or steam auxiliary drive and each mine has a complete fan and power unit ready for operation in emergency.In Dolomite, recently taken data show that fan 1 exhausts 82,000 cubic feet of air per minute at 3.2-inch water-gage pressure, with an analyzed methane content of 0.15 per cent, and fan 2 exhausts 115,500 cubic feet of air at 3.8-inch pressure and 0.10 per cent of methane. In addition, a Capell fan at No. 2 air shaft is a standby or emergency unit.In Mulga recently taken data show that fan 1 exhausts 83,000 cubic feet of air per minute at 3.0-inch pressure and 0.18 per cent of methane, and fan 3 exhaust 119,000 cubic feet of air per minute at 5.4 inch pressure and 0.35 per cent of methane. Fan 2 at No. 2 shaft is a standby or emergency unit for the Mulga mine.The ventilation is on a split system in both mines. All part split and total returns are measured, sampled, and analyzed weekly, requiring one man two days each week. During December, 1930, 77 samples were collected and analyzed in Mulga and 78 in Dolomite. Two weekly reports covering part of December, 1930, are given here so that they can be studied to show control of ventilation in the Dolomite and Mulga mines. In the event that a split sample shows more than 0.50 per cent of methane, immediate steps are taken to lower the explosive-gas content. The reports follow:"

Mar 1, 1932

By E. F. Ferrell

Gold was recovered from scrap electronic 60-40 (tin-lead) solders by drossing with aluminum or zinc at elevated temperatures. The gold, together with other metallic impurities, collected in the dross phase which could then be separated from the molten solder by skimming or filtering. Drossing upgraded the gold concentration by a factor of 10. Further upgrading was achieved by a combination of steps including an oxidation roast and either a combined cyanidation-amalgamation treatment or an aqua regia leach. The gold was then recovered in highly concentrated form from the aqua regia or cyanide solutions by cementation and from the amalgam by volatilization or dissolution of the mercury. The solder was purified by reaction with NaOH to remove dissolved aluminum or with SnCl2 to remove dissolved zinc.

Jan 1, 1976

By R. P. Vinson

The Bureau of Mines examined the effects of high humidity and water droplets on the GCA Corp. real-time aerosol monitor (RAM--l). which uses a lO4mm cyclone preseparator. Tests were conducted both in a laboratory and in a full-scale model mine entry. The laboratory tests were conducted in a test chamber saturated with moisture and water droplets. Under these extreme conditions. the RAM-I responded by indicating dust concentrations of 1-1/2 to 2 mg/m3? although the air was dust free. Within the first 2 h of each test. water accumulated in the cyclone and affected the cyclone particle separation characteristics. resulting in readings of 3 to 4 mg/m3. In addition. condensation formed inside the RAM-I case and affected the liquid crystal display (LCD). However. the full-scale mine entry tests revealed that the RAM-I can function ac-ceptably in an atmosphere of water vapor and water droplets similar to the most severe conditions found in an underground mine.

Jan 1, 1984

By Carl Rampacek

Recent research by the Bureau of Mines has demonstrated that the segregation process has merit for treating oxidized and mixed oxide-sulfide copper ores. The process comprises heating the crushed ore with salt and coke or other carbonaceous materials at about 700° C. to produce fine flake copper, which then is recovered by conventional copper-flotation methods. Bench-scale laboratory tests of a number of oxidized and mixed copper ores assaying 0.78 to 5 percent Cu gave copper recoveries of 73 to 96 percent. The flotation concentrates assayed 21 to 76 percent Cu, depending on the ore being treated.

Jan 1, 1959

By Isaac A. Zlochower, Kenneth L. Cashdollar

The Pittsburgh Research Laboratory of the National Institute for Occupational Safety and Health (NIOSH) conducted a study of the explosibility of various metals and other elemental dusts, with a focus on the experimental explosion temperatures. The data are useful for understanding the basics of dust cloud combustion, as well as for evaluating explosion hazards in the minerals and metals processing industries. The dusts studied included boron, carbon, magnesium, aluminum, silicon, sulfur, titanium, chromium, iron, nickel, copper, zinc, niobium, molybdenum, tin, hafnium, tantalum, tungsten, and lead. The dusts were chosen to cover a wide range of physical properties-from the more volatile materials such as magnesium, aluminum, sulfur, and zinc to the highly "refractory" elements such as carbon, niobium, molybdenum, tantalum, and tungsten. These flammability studies were conducted in a 20-L chamber, using strong pyrotechnic ignitors. A unique multiwavelength infrared pyrometer was used to measure the temperatures. For the elemental dusts studied, all ignited and burned as air-dispersed dust clouds except for nickel, copper, molybdenum, and lead. The measured maximum explosion temperatures ranged from "-1550K for tin and tungsten powders to "-2800K for aluminum, magnesium, and titanium powders. The measured temperatures are compared to the calculated, adiabatic flame temperatures.

By E. J. Murphy

"INTRODUCTION This investigation is a continuation of previous work 3/4/5/ on the gaseous products of permissible explosives with and without sheaths. The range of oxygen balance of the explosives has been considerably increased. As has been shown previously, certain approximate relations exist between the volumes of gaseous products and the oxygen balance. Further systematization of the data is not feasible, since the method of theoretioal calculatln of the gaseous product is not yet satisfactorily developed. In a previously described method, 6/ it has been assumed that the explosion occurs at constant volume and that thermodynamic equilibrium is established. Apart from the presumably less important uncertainty of some of the thermodynamic data, it is not known how the confinement of the shots in the Bichel gage or the Crawshaw-Jones gage should be treated, or whether thermodynamic equilibrium is fully attained; nor can the extent to which the equilibrium composition changes during the subsequent period of expansion and cooling be judged with any reliability. Therefore, no calculations have been attempted. However, in anticipation of possible future theoretical interest and as an aid in answering practical problems, the new data are presented in the same minute detail as was done previously."

Mar 1, 1948

By C. J. Wilhelm

The Bureau of Mines, under its cooperative agreement with the Kansas State Board of Health, has been conducting a study of the various methods of oil-field brine disposal in the oil fields of Kansas. A previous report5/dealt with this problem in the Ritz-Canton field, McPherson County, Kans. A preliminary survey of the Arkansas River drainage area in western Kansas was made during November and December 1934 and January 1935, and a second survey was made approximately one year later during the months of December 1935 and January and March 1936. In addition to the data on the production of oil and 'brine in the various fields and the methods used for handling the brine, the surface drainage and character of the surface soil in the various oil-producing areas were studied.

Jan 1, 1936

By R. S. Olsen

The Bureau of Mines is engaged in a continuing research effort toward the recovery of alumina from kaolinitic clay and other nonbauxitic domestic minerals. Hydrochloric acid extraction of calcined clay is among the acid processes under consideration. Although aluminum is easily leached from calcined clay, the presence of fines and slimes in the leached residue has hindered the application of this and other acid leaching processes. A clay feed preparation method was therefore developed that eliminated the slimy nature and the separation problems normally associated with leached clay residues. The preparation process consists of crushing the raw clay to minus 20 mesh, dampening the crushed clay with a fine water mist while tumbling on a rotating disk, and calcining the misted clay at 750° C. The misting process increases residue settling rates threefold to 9 cm/min (18 ft/hr) and filtration rates by two orders of magnitude. Leaching-kinetics were determined for misted clay feeds in a batch, stirred-tank reactor. Rapid leaching occurred during the first 85 to 90 pct of the extraction. The linear relationship of extraction to time during this initial phase corresponded to a zero order reaction with a rate constant of around 10 pct/min.

Jan 1, 1981

By R. Karl Zipf, Z. T. Bieniawski

"Researchers at The Pennsylvania State University are engaged in a project to understand the mechanics of respirable size fragment formation in coal. The project is based on the premise that a thorough understanding of the fundamental mechanics of fine fragment formation may lead to techniques for reduction and better control of coal dust problems in mines. Presently, it is believed that the mode of fracture propagation which can range from pure tensile to pure shear or any mixed mode in between and the loading or displacement rate can influence the amount of respirable size fragments that are generated on new fracture surfaces during the fracture propagation process The essence of any coal cutting process is one of mixed mode fracture propagation. To study the crack propagation process, a unique mixed mode testing rig was designed and fabricated. This rig is capable of applying loads to a prenotched test specimen that range from pure Mode I (tensile mode) to nearly pure Mode II (shear mode) or many mixed mode loading combinations. It is also possible to apply different loading or displacement rates to the test specimen. With this rig, it is possible to create new fracture surfaces via the different fracture modes and under various loading conditions.These new fracture surfaces are examined with a scanning electron microscope (SEM) to characterize the amount of structural damage and respirable size fragment formation that occurs during the fracture process. Initial observations suggest that the amount of fine fragment formation and the new fracture surface appearance is related to the fracture initiation conditions, particularly the fracture mode and the loading rate. Mode II loading and higher loading rates seem to generate more structural damage and respirable size fragment formation that Mode 1 loading at slower rates.With the mixed mode test rig, the mechanics of fracture initiation for a single crack can be controlled to better understand its influence on respirable size fragment formation. Such understanding may lead to methods which characterize the tendency of specific coal seams to produce undesirable fine fragments during the fracture process, or it may lead to rational recommendations and design guidelines or coal mining machines which inherently produce less dust.IntroductionAs part of a larger effort to reduce the incidence of coal workers pneumoconiosis (black lung) in coal miners, researchers at The Pennsylvania State University are engaged in a project to understand the fundamental mechanics of fine fragment formation in coal. This project is part of a com¬prehensive research effort within the Generic Mineral Technology Center for Respirable Dust which is jointly administered by The Pennsylvania State University and West Virginia University.The principal source of the coal dust in underground mining is the cutting operation. The U.S. Bureau of Mines (USBM) and various European research organizations have conducted investigations into the mechanics of coal cutting for many years. These studies of airborne respirable dust (ARD) formation have concentrated on empirical studies of the various cutting parameters and their effect on ARD for¬mation. The parameters study include depth of cut, cutting speed and bit spacing.(1,2) Other studies investigated the effect of symmetric and asymmetric bit wear and various bit geometries and designs (3-5) Roepke(6) summarized the principals of proper coal cutting to minimize dust formation by recommending to ""cut at maximum depth (maximum advance rate) at all times, at minimum RPM, with the fewest possible bits, having the lowest possible included tip angle."" Most coal in the U.S. is mined with the continuous mining machine which inherently cannot meet these design recommendations.(3)It is recognized that respirable size dust particles are formed and/or liberated by a fracture process. One extremely interesting and useful study performed very early in the USBM dust re"

Mar 1, 1989

By E. K. Stanek, P. Kantabutra, R. A. Wolf

This paper summarizes the cause and effect of induced voltages in multiple conductor cables supplying alternating current power to equipment in under- ground coal mines. The investigation of this phenomenon revealed that the electrical energy produced by the resultant electric arcing between the frames of mobile electric face equipment was of a sufficient magnitude to ignite explosive methane-air mixtures. The results of laboratory tests and field tests made between equipment frames during actual operation in numerous coal mines are discussed. Several methods of eliminating or suppressing the induced voltages to nonincendive levels are also described. It is the purpose of this paper to convey to the mining industry a knowledge of this problem and to recommend methods of eliminating or reducing these induced voltages or arcing currents to safe levels.

Jan 1, 1975

By R. W. Stahl

Coal mining has been revolutionized by the continuous miner. This machine has replaced, or has combined into 1, 3 former operations: Cutting, blasting, and loading. During the 25-year period before this machine was introduced, advances had been made in transportation, but the actual "coal getting" remained virtually the same. As frequently occurs, the multiple-purpose continuous miner introduced a new hazard--more rapid liberation of methane. The coal output formerly obtained from 10 to 20 working places might now be obtained from 1. It is true that circulation of air was generally increased; but the bulk of this machine virtually precludes continuous flow of air across the face, where gas may accumulate. Apprehension about this possible hazard led the Bureau of Mines to test face atmospheres during operation; and Report of Investigations 5288, Methane Buildup During Cutting and Continuous Mining Operations (published in 1956), presents proof that real danger may be present in many otherwise well ventilated mines.

Jan 1, 1958

By John L. Edwards, Anthony T. Iannacchione

There has been a persistent need to forecast roof falls so that miner’s exposure to hazardous underground environments can be minimized. Several monitoring techniques have been developed and are used today with varying levels of acceptance in the mining industry. This paper examines the potential for monitoring microseismic emissions activity as a means of forecasting roof falls. The use of this activity to forecast roof falls has drawn only limited attention, resulting in a lack of published field performance data. This deficiency is being partially addressed by analyzing data obtained during longwall mining at Moonee Colliery in 1998. The Moonee data base contains a wealth of information concerning roof fall forecast parameters and the seismic alarm criteria used to develop these forecasts. Four seismic alarm criteria were developed and used by Moonee with varying degrees of success. Roof falls were forecasted 73% of the time with average forecast times of 54 minutes. Ninety percent of the predicted roof falls had a warning time, i.e., the time between warning and roof fall event, of greater than 1 minute. The fraction of forecasted roof falls decayed logarithmically as a function of warning time, until only 20% of events were predicted more than 100 minutes prior to roof falls. False alarms occurred in 50% of the warnings. Many of the false alarms were quickly followed by a cessation in mining which could have temporarily halted the on-going failure process. If mining had continued immediately after the false alarms, a roof fall may have occurred soon after. The microseismic activity collected from Moonee Colliery demonstrates that techniques to forecast roof rock instabilities in underground mines are possible.