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By Thomas M. Barczak

Longwall roof behavior is characterized by strata displacements in both the face-to-waste (horizontal) and roof-to-f1oor (vertical) direc-tions. The roof support structure provides resistance to this motion by translation of these displacements into vertical and horizontal support loading. Observations indicate that the shield reacts with both a vertical and horizontal force to uniaxial convergence (displacement). However, there are different magnitudes depending on whether the displacement is vertical or horizontal. This makes it possible to use supports as monitors of strata activity and loading. The Bureau of Mines examined this behavior using a linear elastic model of the support structure with two degrees of freedom. Vertical and horizontal load reactions were related to associated displacement actions of the strata. This was done by determining the stiffness of the shield under controlled vertical and horizontal displacement motions in the Bureau's mine roof simulator. This report provides example predictions of strata convergence and isolation of horizontal support loading due to vertical roof convergence using the linear elastic shield model. The report also examines efforts to determine strata behavior by direct measurement of support displacement.

Jan 1, 1987

By S. S. Jenkins Jr.

While the method is seldom used anymore, coyote blasting is an historically interesting way to blast large quantities of rock. It was used extensively in the days before modern fast drills were available and can be very effective in some formations that have a natural breakage pattern. This paper will cover the general principles, some blast design factors and point out several actual blasts including some very large ones.

Jan 1, 2005

By Q. Li, B. Ricks

Over the last several decades mineral concentrate long distance slurry pipelines have been installed and successfully operated. Nearly all were installed via the buried construction method. Their record of depend ability and economy has been well proven. However, these systems operate in regions where seasonal soil frost penetration is shallow or non-existent. In recent years interest in long distance mineral concentrate pipelines in northern cold regions has been increasing. For cold regions one must consider seasonal temperatures and soil frost penetration in order to ensure reliable operations through the year. Herein a case study is developed where heat balance and temperatures for small and large diameter long distance slurry pipelines are compared. The study development is as follows: ?Rheological properties are analysed over range of temperatures from near freezing (4ºC; 39ºF) to relatively very warm (40ºC; 104ºF). ?Then assuming similar climatic conditions, soil properties, and pipeline length, a study is carried out for two pipeline diameters, namely: a small diameter (nominal8 inch; 219.1 mm) and a large diameter (22 inch; 558.8 mm). ?The study focus is on maintaining slurry temperature above freezing throughout the pipeline length by illustrating a decision based on burial depth versus coating the pipeline with insulation.

Jan 1, 2007

By P. D. Bush, E. H. Gates, M. D. Vijayaraghavan, L. F. Engle

The process developed over the last few years by Republic Steel Corporation in conjunction with Colorado School of Mines Research Institute has been used as a basis for the conceptual engineering of full size plants. The paper will cover the equipment design criteria, equipment design itself, and the integration of the complex unit operations. There are unique features of agitation and use of gas media through- out. The paper will provide an illustrative example of the process requirements for a variety of raw material feeds. It will discuss the materials of construction approach required.

Jan 1, 1973

The Matakan Unit of New Ireland, Papua New Guinea is a highly fossiliferous lagoonal deposit containing numerous coal pods and lenses. The unit is strati graphically part of the massive reefal Lelet Limestone of Miocence age. These organic-rich sediments have a high hydrocarbon potential as evident from microscopical observations as well as Rock- Eval pyrolysis data. The coal is varied in regard to dominant macerals, vitrinite being predominant in some parts and pollen and spores present in sufficient proportions to constitute a cannel coal elsewhere. The highly fossiliferous carbo as Rock-Eval pyrolysis data. The coal is varied in regard to dominant macerals, vitrinite being predominant in some parts and pollen and spores present in sufficient proportions to constitute a cannel coal elsewhere. The highly fossiliferous carbonaceous sedimentary rocks associated with the coal are rich in pyrite expressed in the sulphur content (19.7 - 22.8%). A high primary productivity and anoxic sediment pore waters or just above sediment - water interface have given rise to sufficient organic matter accumulations to yield a potential hydrocarbon source rock. Atomic H/C ratios of the coals are between kerogen type III and type II mainly, expressing the mixed nature of the coal and that of the associated sediments is type II. Early generated hydrocarbons (exsudatinite) have formed from pollen exines filling the pollen cavities and in places filling micro- fissures in the surrounding vitrinite.

Jan 1, 1987

By P. K. Sharma

The acidophilic and chemolithotrophic Thiobacillus ferrooxidans bacteria grown in the presence of soluble ferrous ions and solid substrates (sulfur, pyrite and chalcopyrite) as their energy source have been used in the investigations. The cell surfaces are characterised by zeta-potential, contact angle, FT-IR and FT-Raman studies. The adsorption isotherms of the cells on pyrite and chalcopyrite indicate that the adsorption begins on pyrite at a much lower equilibrium cell population than on chalcopyrite. The isotherms tend to level off at a cell adsorption density corresponding to a horizontal monolayer coverage when the geometrical dimensions of the cells are considered. In the presence of cells, the xanthate flotation of pyrite completely depressed, whereas chalcopyrite flotation is unaffected. The results suggest that chalcopyrite can be selectively floated from pyrite, also at a neutral pH region, in the presence of T. ferrooxidans cells.

Jan 1, 1999

By Liu C. H, Juang Y. F

Coal/gas outbursts were one of the rather difficult safety problems faced in the coal mines of this Country, with coal fields characterized by frequent disturbances of folds, faults and pinch-offs. With average mining depth about 500m below surface, several such accidents occurred with up to 500 tonnes of coal outburst. In recent years, after a series of improving countermeasures had been undertaken, gas outburst accidents had been greatly decreased. The characteristics of gas outbursts in Taiwan coal mines include relating to coal petrography, mining depth and the other deformation forces. All these have been investigated, trying to determine the parameter of outbursts under natural conditions. The preventive countermeasures include predicting tests, de-stressing boring in coal seams, the emergency procedures during outbursts and certain improving options.

Jan 1, 1988

By William E. Ford, Edward Salisbury Dana

34. Axial Ratio, Axial Plane. - The crystallographic axes have been defined (Art. 22) as certain lines, usually determined by the symmetry, which are used in the description of the faces of crystals, and in the determination of their position and angular inclination. . With these objects in view, certain lengths of these axes are assumed as units to which the occurring faces are referred.

Jan 1, 1922

By Matthew K. Coy, Paul N. Worsey

The work described in this paper comprised the master’s thesis work of the primary author and was conducted at the Missouri S&T experimental mine. The objective was to determine if rubber tractor treads could be used as an alternative material for blasting mats. These treads are made from steel cable and vulcanized rubber and are very tough. However, once they reach the end of their life on mobile equipment, they are destined for a landfill, or dump site, because they are too tough to recycle. A potential alternative use for them is as blasting mats. Several discarded treads were obtained from Kolb Grading in St. Louis.

Jan 1, 2015

By A. S. Ericson, J. H. Corrigan, E. J. Jahnsen

Calcine is transported from the Reduction Plant at 850°C in insulated hopper cars and charged into three rectangular electric melting furnaces each equipped with three - 18.5 MVA transformers. The electrical energy is applied through six in line prebaked carbon electrodes, and slag and metal are tapped at opposite ends of the furnaces on an intermittent basis. The slag, 5000 tonnes per day, is disposed of by a pot train directly to the dump. The ferronickel, 250 tonnes per day, is tapped into 40 tonne capacity ladles in which it is refined in two ASEA-SKF ladle furnace stations. Casting is done over lip at 1520°C in a pig casting machine with stepless speed control at up to 55 tonnes per hour. The ingots are stacked into self palletizing bundles weighing about 1500 kilograms and are strapped and tagged and transported to the seaport, from which the final shipment is made to the world market. The paper describes constructional details and gives information of both normal operation and start-up and shut-down procedures. Consumption figures for refractory, electrodes, electric energy and refining additions are given and metal chemistry is given before and after refining.

Jan 1, 1979

Laboratory high tension roll separation and the commercial machines available for this purpose are discussed. The shortcomings of these machines are indicated and a machine that overcomes some of these undesirable character- istics is described. A procedure for evaluating laboratory high tension roll separation is described. The use of this evaluation procedure in conjunction with the laboratory separation is described with examples taken from the Dunwich and Hexham processing plants of Associated Minerals Consolidated Limited. Evidence that laboratory testwork results may be directly transposed to operating plants is given. A discussion of the effects of variables in high tension roll separation of mineral sand concentrates concludes the paper, and uses in support results obtained in the metallurgical laboratories of Associated Minerals Consolidated Limited, Southport, Queensland.

Jan 1, 1972

ZAY JEFFRIES (written discussion*).-I have read with much interest Mr. Ruder's discussion of Professor Howe's paper, "The Supposed Reversal of Inheritance of Ferrite Grain Size from that of Austenite." I am yet of the opinion that my first explanation' of Mr. Ruder's samples is substantially correct. In that explanation I did not intend, however, to convey the impression that "reversed inheritance" was the general rule nor even of common occurrence but rather that." Non-inheritance" was the general rule. Mr. Ruder suggests that a " perfectly formed" grain is an indication of inheritance. The grains in my Fig. 52 are perfectly formed and in fact more nearly equiaxed than those in Mr. Ruder's Fig: C,3 yet the grains in the former are known not to be inherited but to have been formed by the partitioning of larger austenite grains. On close examination of Mr. Ruder's Fig. C the very shapes of the grain suggest partitioning. Again, the grain size (25 to 30 grains per square millimeter) is at least 10 or- more likely 20 times smaller than might be expected of the austenite from which these grains were .formed under the given time and temperature conditions. Mr. Ruder's newer results on electrolytic and Armco iron are most interesting and instructive. His results fit in. nicely with my conclusions 5, 6 and 10.4 His photographs, however, indicate that the thickness of the pieces of sheet metal are such that abnormal grain growth is promoted. He indicates that equilibrium grain size after heating to 950° C., with furnace cooling, is about the same as his Fig. 1, above. I estimate this to be approximately one-half -grain per square millimeter, or 40 times as large as I have obtained with the same material (Armco iron) after heating Y4-in. bars to 1300° C. for 2 hr. and cooling in the furnace. The effect of thickness of sample on grain size is one which needs more attention.

Jan 3, 1918

Alternative processes for converting coal to liquid products and their stage of development are outlined. The merits of hydrogenationprocesses in general, and the solvent refined coal process in particular, are stressed. Bench scale experimental hydrogenation procedures used by the Australian Coal Industry Research Laboratories Ltd. (ACIRL) to study the liquefaction of Australian coals and correlations between properties of such coals and their conversion to liquid products are described. Factors involved in assessing investment and operating costs for modern hydrogenation based coal refineries of different capacities are described with reference to a recent study undertaken in N.S.W. The significance of coal properties such as yield and yield structure of total liquid products and how they and other factors can influence the economics of the coal refining operations are discussed.

Jan 1, 1977

By Luciano B. Oliveira, Angela O. Costa, Sergio N. Monteiro, Luis Guilherme C. Marques

"Biofuels are gaining a relevant role in today’s world not only as a solution for the decreasing petroleum reserves but mainly as a positive contribution to the efforts in global warming mitigation. In Brazil, since 1975, the replacement of gasoline by ethanol started a so-called PROALCHOOOL program, which is now being complemented with the replacement of petroleum diesel by biodiesel. This biodiesel program was officially created in 2005 with mandatory goals, supported by legislation, of 2% addition in 2008 and 5% addition in 2013 into all commercialized regular diesel. In this work, a critical analysis of the Brazilian biodiesel program is presented. The technical aspects related to the different raw materials, including wastes, available for biodiesel conversion as well as the economical conditions associated with production costs and market logistic are discussed. The environmental benefits associated with the retention of greenhouse gases are also discussed.IntroductionToday the commonly accepted fact that the petroleum world reserves are probably passing through a maximum and start declining in terms of the total amount that can be extracted by existing technologies is motivating significant changes in our society. The continuous increase in the price of gasoline and other liquid fuels is an immediate worrisome and visible consequence. However, more than an economical problem, our civilization is already facing the effects of global warming, due to CO2 emission from burning fossil fuels, mainly from coal and petroleum. It is now realized that a large scale solution for these problems demands the prompt substitution of non-renewable fossil fuels by others that, in addition of being renewable, have a relatively lower contribution to the greenhouse gases."

Jan 1, 2008

Capture airborne coal dust generated by a continuous mining machine to reduce workers? dust exposure and to improve face visibility. Approach Develop a low-profile dust collector system which can be mounted on the boom of a continuous miner. How It Works When coal is mined with a milling head continuous miner, a substantial amount of coal dust (respirable and non-respirable) escapes the dust suppression sprays at the cutter head. This can cause poor visibility around the cutting head and can expose the workers to high levels of respirable dust. A practical means of removing this dust is with a scrubber mounted directly on the mining machine. Under a Bureau of Mines contract, a low-profile, machine-mounted dust collector (MMDC) was developed to avoid adding extra height to the continuous

Jan 1, 1983

By R. U. Jackson

FACED with rising costs, the mining industry is looking to new methods and equipment to supply the relief necessary for profitable operation. Conveyor transportation is rapidly taking a superior position to motor tramming in underground mines because of lower installation, maintenance, and operating costs. Haulage is always a critical problem in underground mining. The ease of operation and flexibility of a haulage system can have an important effect on ultimate mining cost. With the average tenor of ores on the downgrade, larger tonnages are required for the same metal recovery. This selection of a tramming system can be the key to a successful, paying plant. Because this shift is being made at an ever advancing rate, it may become necessary to tailor mining operations to the transportation system, rather than to select a haulage system fitting set mining methods. In choosing a haulage system, the relative costs of the various methods are of the greatest importance. Adapting the mine to one or the other type of tramming is not considered in the cost analysis, and very likely would make little difference, outside of location of drifts and raises. In the cost sheet, the problem presents recommendations for a conveyor installation and a comparison of equipment, installation, operation, maintenance, and power costs are made. Under the track haulage estimate, no allowance was made for dumping equipment at the shaft pocket or bin. If this equipment was added to the balance sheet, the additional

Jan 1, 1952

By A. W. Khair, S. S. Peng

Discussion by J. Parker Gentlemen; Rainy day in Upper Michigan, a good time to catch up on reading. Am doing that, and have a couple of questions concerning the K and P paper on roof problems and supports. I wonder if the authors can enlighten me. The compressive strength of the coal was reported as 4.4 MPa (633 psi) and compressive stresses measured in the coal seam were reported at around 27.6 and 48.2 MPa(4000 and 7000psi ). Can such a soft coal actually contain such a high level of stress? Can it be measured as if the material were elastic, or does the coal behave plastically? Can that stress level be confirmed with hydraulic load cells? And if the coal is so soft, and if it is plastic, why is the stress field not hydrostatic'? The intact roofrock appears to be unusually strong, with compressive strength reported at around 145 MPa (21,000 psi), and some failures were noted as soon as the rock was exposed. Were tests run to find out how that rock responded to the addition of moisture, from sprays or from humid air? Did moisture weaken the rock? Did it cause the rock to expand quickly, thus to induce internal compressive stress? How can the near-vertical cutters, as shown in the photographs, be attributed to primarily horizontal stresses? Did the cutters follow any particular pattern in the development panels, which might be related to a particular stress pattern? For example, did they always appear alongside the stiffest pillar? Or always along the northwest rib? Was there any evidence of the pillars and entries "rotating" under the influence of differential horizontal stresses? How much did the entries and pillars rotate as the longwall face approached and passed? After rooffalls, did the openings assume shapes which would indicate a preferred shape in that stressfield and geology? Did crosscuts always survive without damage, as shown in the sketch?

Jan 1, 1992

Diamonds have been known in Australia for many years, especially in association with alluvial gold and tin occurrences. Exploration for primary sources in the Kimberely area of Western Australia has been carried out since 1968, culminating in the discovery, in 1979, of the Argyle Kimberlite No 1 (AK1) kimberlite pipe. Various techniques have been used in the search for diamonds such as geologic interpretation, aerial photography and Landsat, soil geochenical techniques, geophysics, and stream sediment sampling. Stream sediment sampling, a method developed in South Africa, using the detection of indicator minerals derived from kimberlites in gravel samples, has had wide application and success in Australia. Nevertheless, although Australian diamond bearing kimberlite and lamproite rocks contain some of the classic indicator minerals, their concentrations are generally much lower than in South Africa and Russia. Despite this paucity of indicators, stream sediment sampling is still the best known and most commonly used method of diamond prospecting in Australia. Small samples are treated by hand but larger samples require the use of diamond pans, jigs or heavy media separation plants. Each of these methods has advantages and disadvantages. The final concentrate is passed over a grease table or subjected to x-ray sorting.

Jan 1, 1984

By Paul B. Queneau, Barry J. Hansen, D. Erik Spiller

Most lead and zinc secondaries are recycled pyrometallurgically. However, many problems encountered in secondary smelters have been solved by addition of physical concentration and/or hydrometallurgical processing steps, with resulting important environmental benefits. U.S. secondary lead and zinc operations are described, covering conventional smelters, EAF-dust treaters, and zinc sulfate/fertilizer producers, including plant capacities, technologies, and outputs. During the past two decades, remarkable advances have been achieved by recycling spent lead-acid battery components. Interaction between primary and secondary zinc producers, the fertilizer industry, and the zinc chemical industry has substantially decreased waste generation.

Jan 1, 1993

Various software packages are discussed. These are components of an Integrated Planning and Scheduling System developed by MVM with the aim of providing up-to-date information for the Whaleback operation on: 1. Mine Topography. 2. Status of equipment in the mine. 3. Material moved from and within the mine. 4. Volume and density of same. 5. Quality of same.

Jan 1, 1986