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By W. A. Selvig

"INTRODUCTION In 1942, Lowry and Junge 3/ reported the results of a statistical study of errors for the proximate and ultimate analysis of coal and coke when made according to the standard Methods of Laboratory Sampling and Analysis of Coal and Coke (D271-42) 4/ of the American Society for Testing Materials. Some of the laboratories that cooperated in the investigation reported difficulty with determination of the volatile matter of anthracite and low-temperature coke. The small number of analyses reported for these particular fuels was considered inadequate to justify definite conclusions regarding the precision of this determination.The investigation described in this report was made at the request of Committee D-5 on Coal and Coke, A.S.T.M. (A. C. Fieldner, chairman), to secure additional information regarding the errors of the volatile matter determination for anthracite, low-temperature coke, and subbituminous coal; the last fuel also gives trouble in this determination, The committee has recognized that the allowable differences between duplicate determinations of volatile matter for these fuels as given in the standard methods are perhaps too stringent and may require revision."

Dec 1, 1943

By Menzhans Guo

A coal bunker basically acts as a buffer and regulator to reduce the interruptions between its proceeding production system and succeeding haulage system so as to maximize the availability of the whole system. Although such a role has long been recognized, quantitatively studying it is still rarely seen in the literatures. Its unique characteristics, coupled with numerous transitional states, make it very complex to describe the state transitional process in analytical models and, also very difficult to seek an analytical solution. Moreover, the analytical models inappropriately consider the state of bunker being full or empty as a kind of failure, therefore, by no means can they realistically describe the impact of the difference between rates of coal flowing to and from a bunker on the system availability. In light of this, Monte Carlo simulation methods are suggested to reach an approximate solution. In comparison, simulation methods are simpler and more effective than analytical approaches. Applications of simulation methods to a Northern colliery for determining bunker size from the viewpoint of maximizing system's availability are discussed. The results are satisfactory.

Jan 1, 1992

By R. H. Busch, S. M. Loscutoff, F. T. Cross, R. E. Filipy, P. J. Mihalko, R. F. Palmer

INTRODUCTION During the last decade, several studies in France (e.g., Perraud et al. , 1970; Chameaud et al., 1974, 1979 and 1980) and the United States (e.g., Stuart et al., 1978; Cross et al., 1978, 1980 and 1981) have demonstrated the systematic production of emphysema, fibrosis and tumors in the lungs of animals exposed to radon daughters alone or to mixtures of uranium-mine air contaminants. The studies in beagle dogs have been particularly interesting because of the uncertain etiology of the disease and the (apparently) diverse results of the studies at the University of Rochester and the Pacific Northwest Laboratory (PNL). In the Rochester studies, reported by Morken (1973), beagle dogs were exposed to "normal" room air dust loads and radon daughters from 200 to 10,000 WLM*, delivered in 1 to 50 days (rate of delivery, about 200 WLM per day of exposure). Histological examination of tissues was conducted at 1, 2 and 3 years after exposure for all exposure levels. No cancers were noted in these dogs that received estimated alveolar doses of 34 to 1700 rad (0.34 to 17 Gy). Pathologic changes were found only in the alveolar and bronchiolar regions of the lung. These changes were small, subtle, variable, and widely separated, involving only a very small fraction of lung tissue. Lesions appeared as focal thickening of alveolar septa, with some metaplasia of alveolar cells and some hyperplasia of bronchial epithelium. In the PNL experiments reported by Cross et al. (1978), beagle dogs were exposed in lifespan studies to mixtures of radon daughters (rate of delivery, about 14 WLM per day of exposure), uranium ore dust and cigarette smoke. One group of dogs was exposed to cigarette smoke alone. Except in control and smoke-only groups, the dogs died within 4' years of the first radon daughter exposure, or were killed when death appeared imminent because of pulmonary insufficiency (characterized by rapid, shallow breathing). Control and smoke-only animals were killed at periods corresponding to highmortality periods in the groups exposed to radon daughters and mixtures of uranium ore dust and cigarette smoke. Emphysema and fibrosis were much more prevalent and severe in the lungs of dogs exposed to the mixtures. These dogs also had adenomatous lesions, which progressed to squamous metaplasia of alveolar epithelium, epidermoid carcinoma and bronchioloalveolar carcinoma. Pathologic changes in the upper airways of these dogs were most prominent in the nasal mucosa, and included a few squamous carcinomas in the nasal cavity. Respiratory tract neoplasia was noted after ~4 years exposure and at cumulative exposures exceeding approximately 12,000 WLM. Apart from differences in associated carrier aerosol (room air dust vs. uranium ore dust) and radon-daughter exposure rate (200 WLM/day, shortduration exposure vs. 14 WLM/day, long-duration exposure), the most obvious difference in the Rochester and PNL studies was the observation time following exposure (3 years maximum vs. >4 years). Although neoplasia may not have been observed in the Rochester animals because of the earlier termination of the experiments, it is surprising that other lesions, such as prominent fibrosis and emphysema, were not reported. A follow-up study (reported here) is currently in progress at PNL to determine the pathogenic role of uranium ore dust alone and, in particular, to clarify the role of the ore dust in the production of the massive pulmonary fibrosis observed in the earlier study. Pulmonary function testing (a recently acquired capability) was included in the follow-up study as an indicator of progressive change in lung tissue. MATERIALS AND METHODS Chronic (4 hr/day, 5 days/week) exposures began when the dogs were about 2 1/2 years old. Two identical exposure chambers provided space for simultaneous, head-only exposure of 24 dogs to ~l5 mg/m3 carnotite uranium ore dust. An aerosol diffusion system was incorporated in each chamber in order to channel fresh aerosol past each dog's head; uranium ore dust was added to the inlet room air with Wright Dust Feed Mechanisms* (WDFM). Uranium ore dust and condensation nuclei concentrations were measured daily; chamber aerosols were monitored occasionally for particle-size distributions as described for previous hamster experiments (Cross et al., 1981). The carnotite ore used in these experiments, from the Mitten mine in Utah, was furnished in 1970 through the Grand Junction, CO Office of the (then) U.S. Atomic Energy Commission (now the Department

Jan 1, 1981

"EAF dust is categorized as a hazardous solid waste. EPA approves only two treatment methods: either sending the dust to zinc recycling facility, or stabilizing it first and then disposing it to a specially-lined landfill. Both treatment methods are costly to EAF steelmakers. In order to reduce the cost and even better to make profit from the dust, EAF steelmakers need to find a costeffective technology to separate zinc from EAF dust. This paper is dedicated to discussion of a novel recycling strategy: in-process separation of zinc from EAF dust. The concept of in-process separation of zinc from EAF dust is first defined, and then a simple Zn concentration model is developed. From this model, two approaches of in-process separation of zinc from EAF dust are derived: (1) prematurely capturing dust at very high temperature when zinc is still in vapor status, (2) prematurely collecting dust immediately after quickly cooling EAF off-gas from high temperature to low temperature. Next, thermodynamic analysis is conducted to understand zinc behavior in EAF off-gas. It is demonstrated in theory that zinc is in vapor status while it exits from electric arc furnaces. At last, recycling routes and economics of in-process separation of zinc from EAF dust are discussed.IntroductionElectric arc furnace (EAF) plays an increasingly important role in steel production. According to USGS, steel production from electric arc furnaces has long exceeded that from basic oxygen furnaces [JJ. In 2009, electric arc furnaces produced 64% of total steel in the United States.Along with the fast growth of EAF steel production, generation of EAF dust is also rapidly increasing. A survey by AIM Market Research showed that 10 - 20 kg EAF dust was generated for every ton of EAF steel produced [2] In 1999, the United States alone produced 770,000 metric tons of EAF dust [3] In Europe, annual generation rate of EAF dust is more than one million tons [4-5]. In Japan, about 450,000 tons of EAF dust is produced each year [6] Globally, total generation of EAF dust was estimated to be more than 5 million tons per year [5] EAF dust is categorized as a hazardous solid waste since it often contains heavy metals, such as lead, chromium and cadmium. US Environmental Protection Agency (EPA) approves only two methods for treating EAF dust: (1) recycling the dust by EAF-dust recyclers, and (2) specially landfilling the dust for disposal after it is chemically stabilized. These two methods of treating EAF dust are both very costly to EAF steelmakers. It was estimated that a fee of $150 to $200 per ton of EAF dust was paid for various treatment options, which added approximately $2 - 3 cost for every ton of liquid steel produced by electric arc furnaces [?J."

Jan 1, 2011

By K. A. Natarajan, J. M. Modak, P. Anand

A microbial survey of Jamnagar bauxite mines in Gujarat, India, revealed the indigenous presence of a variety of autotrophic and heterotrophic bacteria and fungi associated with the ore body and water ponds in the vicinity. Among these, bacteria belonging to the genera Thiobacillus, Bacillus and Pseudomonas are implicated in the weathering of aluminosilicates; the precipitation of iron oxyhydroxides; the dissolution and conversion of alkaline metal species; and the formation of alumina, silica and calcite minerals. Fungi belonging to the genus Cladosporium can reduce ferric iron and dissolve alumina silicates. Biogenesis thus plays a significant role in bauxite mineralization. Various types of bacteria and fungi, such as Bacillus polymyxa, Bacillus coagulans and Aspergillus niger, were found to be efficient in significant calcium solubilization and partial iron removal from bauxite ore. Probable mechanisms in the biobeneficiation process are analyzed. Biobeneficiation is shown to be an effective technique for the removal of iron and calcium from bauxite ores for use in refractories and ceramics.

Jan 1, 1998

Jan 1, 1949

To improve a miner's chance of survival during an emergency by providing immediately avail-able breathable air and protection from toxic gases until a longer-duration breathing apparatus, stored nearby, can be reached. Approach: A belt-carried apparatus which can provide a closed-circuit atmosphere for ten minutes breathing has been developed under a Bureau of Mines contract. How It Works: Water vapor and carbon dioxide in the user's exhaled breath are removed, and oxygen is supplied, by chemical reactions. When the user exhales into the mouthpiece, water vapor in his breath reacts with potassium superoxide (KO2) stored In the canister to produce oxygen. The other product of this reaction (KOH) reacts with carbon dioxide and removes it from the air. The oxygen-enriched air then flows from the canister into two breathing bags. When user inhales through the mouth, that air is drawn out of the bags, makes a second pass through the chemical-containing canister, and flows into the mouthpiece tube. A nose clip is worn to seal off the nasal passages.

Jan 1, 1975

By W. Krieglstein

Due to the natural variability of ores, it is necessary to carefully test flotation behavior of flotation cells before designing flotation circuits. For performing quick and versatile tests in the laboratory, Siemens developed a laboratory-size Hybrid Flotation Cell, which has been down-scaled from the 300 m³/h production cell to a 0.6 m³/h flotation cell. This small cell is being used as a test bed for technical and chemical concepts, the improvement of decisive components and the characterization of customer ores. In this study the evaluation results for Andean porphyry copper ores are shown. Total recovery rates of the order of 45 to 50 % have routinely been achieved in a single flotation cycle over a wide range of feed grades. In addition, the Hybrid Flotation Cell has proven to be particularly well suited for the flotation of fine particles below 20 µm down to below 1 µm, at high recovery rates and concentrate grades.

Sep 1, 2012

By E. G. C Charlesworth, M. J. Robertson

"Gold mineralization in the Main Reef Complex at Sheba Gold Mine is hosted within shear zones in a sequence of shales and greywackes of the Fig Tree Group. Competency contrasts between these rocks and a steeply dipping chert unit provided a locus for the development of right lateral steeply dipping shear zones. A set of flatter dipping shear fractures crosscut these zones with their intersections defining a system of en échelon ore shoots. Mineralization is both of vein type and disseminated strata-controlled replacement type. The latter occurs mainly within the wall rocks to the shear zones. Arsenopyrite and pyrite are the major sulfides, with arsenopyrite being confirmed largely to greywacke beds and pyrite to the more iron-rich shale units. Gold was introduced, together with minor sphalerite, pyrrhotite, chalcopyrite and early arsenopyrite, toward the end stages of a first pyrite phase. The mineralizing fluids were introduced along dilated cleavage planes and, emanating from these, produced a series of replacement fronts. Mineralization was syntectonic to late tectonic and occurred under conditions of progressive deformation, resulting in sulfides which are concentrated in the hinges of shear-related folds and semimassive sulfides within tension fractures which are folded, attenuated and fractured. An analysis of the structures shows a sequence of events in which an initial ductile simple-shear event with a steep sense of movement was succeeded by a more brittle strike-slip event. Mineralization is temporally related to the latter. This evolution in structural style was probably related to reactivation of the Sheba Fault as a transcurrent fault during emplacement of large granitoid bodies."

Jan 1, 1994

Incremental sampling is defined as a solution to fight segregation, the theory is demonstrated and theoretical and practical aspects are discussed. The number of increments necessary for successful sampling is discussed. As an application, riffle splitter division is reviewed.

Mar 1, 2010

By J. E. Forciea, O. E. Palasvirta, L. G. Hendrickson

All pilot and commercial plants working with Mesabi Range taconite employ wet magnetic separation. Progress is being made with a dry magnetic process,9-11 but this has not yet been applied to taconite except in the laboratory and pilot plants. Flowsheets in all five plants are similar, including multiple stages of grinding, each followed by magnetic separation, which rejects a finished tailing. The flowsheet in Fig. 1 is used in the preliminary and commercial plants of the Erie and Reserve mining companies and in Unit C of Oliver's Pilotac plant. At Erie the desliming operation is omitted. In the Reserve plants two ball mills are used with each rod mill. Pilotac uses flowsheet 2 in Unit A-B and has also tested flowsheet 3. Principal differences in the three flowsheets are the number of grinding stages and the type of roughing. The terms open- circuit roughing and closed-circuit roughing are best defined by the diagrams.

Jan 12, 1958

By Clayton A. Signor

Abstract: Expansive soils cause more damage to structures annually than a combination of other major natural disasters. Because of the cost to our society, all means and methods need to be fully explored to mitigate the problems associated with expansive soils. This study will present a foundation design approach that is underutilized in this application, driven piles. The main objective of the study is to present pile test results and analysis from four driven pile project sites in three types of expansive soils found in central Texas: Del Rio formation, Taylor/Navarro formation, and expansive alluvium. High strain dynamic pile tests were conducted on each of the four studies with rigorous signal matching analysis from the CAse Pile Wave Analysis Program (CAPWAP). Ultimate pile capacities ranged from 73 to 311 kips with an average of 61% of the total capacity coming from the pile shaft and were two to six times the structural capacity needed. Allowable loads calculated from Modified Gates dynamic formula best modeled allowable test results. Average unit skin frictions ranged from 0.50 to 4.71 ksf. Restrike pile tests of 1 to 17 days after initial driving reported 30 to 100% shaft capacity gain. All open-ended pipe piles driven produced soil plugs ranging from 4 to 14 feet thick. Small diameter, thick-walled, open-ended pipe piles reached penetration of twice the depth of designated zone of seasonal moisture change without problem. The observed production rate of the driven piles was on average 8 minutes, which implied daily production of 15 to 40 piles. Predrills or augered holes should be specified for underground obstructions found in soil investigation.

Ventilation 'is currently used in mines to sustain human life, prevent explosions, and provide a more healthful work place. Future automated-mining systems could use ventilation techniques quite. different from today's practices. The Bureau of Mines is anticipating various methodologies for ventilating the automated mining systems which are now beginning to emerge in the mining industry. This paper examines the special ventilation requirements for automated mining systems. Topics include requirements for automated systems, current studies with blowup ventilation tubing, and ventilation of two types of highwall -ripper type mining machines.

Jan 1, 1990

By D. C. Jones

The term "coal-mine mechanization" is definable in several ways. In its general application it can mean the use of machines instead of manpower in each of the various mining activities necessary for the production of coal—so that under this definition a mine that uses mechanical coal cutters could be classed as a mechanized mine. Common usage, however, insists that a mechanized mine is one in which machines are used for the entire process of mining or extraction and transportation of the coal. For the purpose of this paper, then, the second definition of "coal-mine mechanization" will be used, and practices employed in mines where the greater part of the production is obtained through the use of mechanical loaders and conveyors will form the basis for this discussion. Physical Contact Hazards If we were to group all the hazards that accompany the use of mechanized equipment in a mine, the predominant class would be that which, for want of a better name, might be termed the "physical contact" hazards; that is, all the sources of danger that lead to accidents through physical contact of workmen with machines. A survey of accidents in a group of mechanized mines indicated that this class of hazards may be responsible for more than half the number of accidents in mechanized mining. For example, of 21 mining-machine accidents at one mine, 14 were of the physical contact type; of 14 loading-machine accidents at the same mine, 8 were the result of physical contact. Certain of these hazards are controllable through the use of guards— a guard over the cutting-machine bits when the machine is being trammed from place to place, or a chain or some similar locking device around the cutter chain, so that an accidental blow or push against the bit control will not cause the cutter chain to move. Other hazards, such as the possibility of a loader operator having his foot crushed by a crawler tread, or a brakeman being hit by a loader boom swung too far to one side while a car is being loaded, might be subject to control through the use of guard devices, but the reduction or elimination of all physical contact hazards by such methods does not appear feasible. Every accident of the physical contact type should he investigated to discover whether guards could have prevented it, but often the only way in which to combat these hazards will be through the awakened consciousness of each workman as to the danger that exists if he indulges in unsafe practices. A good approach to control of accidents in any mine is the establishment of a set of safety rules or operating rules. The intent of such rules is to provide guides far the workmen to follow in the operation of equipment. Frequently the workmen have no regard for such rules, and observance is obtained only through compulsion on the part of management. An interesting development in connection with-the formation of safety rules occurred during a training program for employees in the

Jan 1, 1947

By D P. Yang, Yang R. G

The laws of throwing and heaping of engineering blast are important for making use of throwing and heaping of thrown body to form certain shape, such as building dams by directional blast. The article is to apply Ballistic theory of single thrown body to take the throwing course of thrown body as the movement of particle system, and then delimit the total of thrown body into units of thrown bodies, and regard the heaping shape of single thrown body as a perfect triangle, and found a quantitative relation between macro-geometry parameters of perfect triangle and designed parameters of explosives. The theory has been adopted in blast practice and gotten good effects.

Jan 1, 1999

By Robert Stefanko

With passage of the Clean Streams Act of the Commonwealth of Pennsylvania and its impact on the coal industry, considerable research has been conducted to explore various approaches to the problem, including deep-well disposal. Available drillhole data from gas and oil wells were used to develop cross -sectional maps for various portions of the state and potential disposal zones were evaluated. Bethlehem Mines Corp., faced with a severe water problem at its Marianna operation in Washington County, cooperated with the Dept. of Mining at The Pennsylvania State University in establishing a 1500-ft well into the Salt Sands for the purpose of determining the feasibility of mine water disposal. The thickness, porosity, and permeability of the formation at the well site proved to be below what had been anticipated from drillhole data. Further, subsequent hydraulic fracturing did not improve the flow characteristics of the well; pumping pressures remained in the range of 1800-2000 psig for disposing of water at the rate of 150 gpm. The legal problems of disposal at the site were very formidable. When the Salt Sands proved to be less than satisfactory, permission could not be obtained to dispose in other promising formations. The paper details many of the problems associated with the experimental well and makes an assessment of the potential for deep-well disposal of mine water. The concept of disposing of liquid industrial wastes by deep-well injection is not a new one. Brines associated with crude oil long have been disposed of in this manner, with the additional benefit of aiding secondary oil recovery. More recently, with the expansion of nuclear energy, the lethal, highly radioactive wastes which are by-products of the fission process have created severe disposal problems. During the past ten years, a variety of industries have resorted to subsurface disposal, some of the details of which are given e1sewhere.l,2 The list reveals wide variations in injection rate, pumping pressure, cost, and waste disposition. Included are successful installations in Western Pennsylvania. Enactment of more restrictive clean-water legislation in Pennsylvania recently had a great impact on the coal industry. Among its provisions was the reclassifica-tion of most mine water as industrial waste whose dis-posal is prohibited in any stream of the Commonwealth. This had the effect of accelerating research in a variety of areas, although treatment methods still retained primary interest. When a feasibility study of deep-well disposal was proposed to the Pennsylvania Dept. of Mines and Mineral Industries, the Coal Research Board (CRB) approved it. This paper summarizes the efforts on this project. Acid mine water is a chemically complex liquid. having no definite quantitative relationship among its constituents. However, it is the iron disulfide (FeS2) associated with practically all coal seams that produces the objectionable products present in acid mine water when combined with air and water. The principal contaminants are sulfuric acid (H2SO,) and ferric hydroxide (Fe(OH)2. Ferric hydroxide is a rust-colored gelatinous precipitate that coats stream bottoms and destroys aquatic life. However, other ions and bacteria are present in acid mine water in varying amounts.

Jan 1, 1971

By M. Bidart, V. Sawyer, M. Saunders Macdonald

A number of open pit gold mines in Nevada extract ore from areas that are below the natural groundwater elevations. This necessitates dewatering, which requires a method for the disposal of the extracted water. Some of these open pits extend well below, the water table with dewatering volumes greater than 10,000 gpm (38,000 L/min). Some mines with large volumes of dewatering water have constructed reinfiltration basins to reintroduce the water into the groundwater system at a point some distance from the pits. This paper presents an overview of the state of the art of reinfiltration projects, including the permit process for such projects in Nevada. The paper includes the necessary engineering considerations.

Jan 1, 1997

By M. H. Kline, T. J. Ballard

"INTRODUCTION The Cranberry magnetite deposits occur in pre-Cambrian granite-gneiss in a belt extending from 3 miles southeast of Cranberry, N. C., to about 6 miles southwest of Magnetic City, Tenn. The belt forms a curve, elongated to the north, approximately 26 miles in length.The Bureau of Mines investigation has been confined to the eastern part of the belt, comprising the area from Fork Mountain, Avery County, N. C., to the Hcupscup Knob prospects in Carter County, Tenn.The deposits were worked at least as early as 1820. The Cranberry Iron & Coal Co. and its successors operated the Cranberry mine intermittently for about 50 years until 1930, when operations were abandoned.The magnetite rock is amenable to concentration. Numerous laboratory tests and pilot-mill operations have proved that a high-iron, and low-phosphorus concentrate can be obtained by fine grinding and magnetic, separation, the quality of the concentrate depending upon the extent of grinding. The principal objectives of the Cranberry project were threefold.The primary consideration for beginning exploration of the deposits was the need for developing additional deposits of high-grade iron ore during the war and for replenishing the war's depletion of iron-ore reserves for the peacetime economy. The emergency did not permit logical sequence bf development, and it was necessary to begin drilling before the geophysical survey was completed. The first drilling was begun at the Cranberry mine; and the holes were located from the geological data, coordinated with the position of the mine workings."

May 1, 1948

By A. Redman

Aquatic organisms are sensitive to free cyanide (HCN) though the presence of certain metals that can form stable complexes and thereby reducing both the amount of bioavailable cyanide. Recent work has suggested that consideration of HCN rather than total cyanide can provide the basis for water quality criteria. Cyanide is often present in complex effluents that affect speciation and bioavailability. We have developed a model to predict the speciation of cyanide in complex effluents and have shown that this model can predict the toxicity of metal-cyanide complexes in terms of HCN. This study evaluated available cyanide toxicity exposures with this model to assess the role of water chemistry (e.g., metal-cyanide interactions) on the observed. Toxicity endpoints based on total cyanide ranged over several orders of magnitude for a variety of metal-cyanide mixtures. However, predicted HCN concentrations among these same tests described the observed toxicity data to within a factor of 2. Aquatic toxicity can be well described using HCN though in certain metal-cyanide mixtures toxicity was jointly described by HCN and elevated levels of bioavailable metals. This work was performed in support of an industry-sponsored reassessment (Gensemer et al 2006) of the U.S. EPA water quality criteria for cyanide (EPA 1985) using free cyanide as the basis for the re-calculation. The work presented in this manuscript presents technical support for using free cyanide as the preferred basis for this recalculation.

Jan 1, 2011

By Shijie Qu, Paul N. Worsey

Pre-splitting has become widely adopted for the formation and protection of final surface rock excavation profiles in both large scale civil construction and highway rock cuts. Jointing has been shown to affect the success of pre-splitting and the smoothness of the resulting profile, however, only closed joints have been investigated. Frequently jointing that is closed at depth is open at and near the surface due to weathering, reduced stresses and ground water percolation. In many instances, problems are associated with surface rock layers whereas at depth these problems are either reduced or do not exist.

Jan 1, 1987