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By Kevin Andrews, Zach Agioutantis

Analysis of Coal Pillar Stability (ACPS) software, released in 2018, integrates numerous empirical pillar design techniques. The ACPS program incorporates methodologies originally available as design tools from the National Institute for Occupational Safety & Health (NIOSH), including Analysis of Longwall Pillar Stability (ALPS), Analysis of Retreat Mining Pillar Stability (ARMPS), Analysis of Multiple Seam Stability (AMSS), and concepts including Coal Mine Roof Rating (CMRR), the Mark-Bieniawski pillar formula, and pressure arch loading. The design methodologies that are the basis of ACPS were developed via analysis of significant amounts of real-world data and have been standards of the United States coal industry for decades. While there are empirical factors built into ACPS, making it ideal for use in U.S. coalfields, the concepts in the program have proven to be applicable in variable mine settings, and the software was developed to allow for user-based, site-specific modifications of key design inputs. Application of ACPS to cases outside the regions for which it was developed must be approached carefully, and continuous development of site-specific data is mandatory. A case study is presented involving the application of ACPS to assess pillar stability and assist future design for an underground lignite mine in Eastern Europe. Assessment of in-mine observations, review of the geology of the lignite mine, and evaluation of specific conditions associated with a failure event resulted in “calibration” of key input factors to ACPS. Scenarios evaluated with ACPS suggest that pillar strength and overburden depth are key factors for the determination of pillar stability and design in future areas.

Jun 25, 2024

By Willem Le Roux

Occupational health and safety is regulated by statute and common law. South Africa has, like many other countries, legislated extensively on occupational health and safety. Despite the body of legislation, the common law continues to play an important role as far as it concerns contractual, delictual and criminal liability. Two major Acts regulate occupational health and safety viz. the Occupational Health and Safety Act, No. 85 of 1993 (?OHASA?) and the Mine Health and Safety Act, No. 29 of 1996 (?MHSA?). The MHSA applies to mines and works as defined and related aspects. OHASA applies to other industries but does not apply to employers and workplaces to which the MHSA and certain matters covered by the Merchant Shipping Act, No. 57 of 1951 apply. See section 1(3) of OHASA. 2 The employer?s health and safety obligations in terms of the MHSA 2.1 Section 2(1) of the MHSA provides amongst others, as follows: ?The employer of every mine that is being worked must: (a) ensure, as far as reasonably practicable, that the mine is designed, constructed and equipped: (i) to provide conditions for safe operation and a healthy working environment (ii) ... (b) ensure, as far as reasonably practicable, that the mine is commissioned, operated, maintained and decommissioned in such away that employees can perform their work without endangering the health and safety of themselves or of any other person?.

Jan 1, 2011

By E. M. Furness, A. S. Henderson

ORIGINALLY the Babbitt experimental plant grinding circuit consisted of one rod mill 10 ½ ft diam by 12 ft long in open circuit followed by two ball mills 10 ½ ft diam* 12 ft long in parallel circuit. Shortly after operations commenced it was apparent that the rod mill could not function satisfactorily at the required 125 gross tons of ore per hr. Attempts to operate at this rate produced: 1) excessive tramp material over rod mill trommel screen which could not be handled in this open circuit and 2) excess build-up of coarse ore in the ball mill circuits because of inadequate rod mill grinding. Since Reserve Mining Co. ore must be ground to 85 pct -325 mesh to produce a satisfactory iron concentrate, an efficient and controlled grinding circuit is highly important. The first step in trying to resolve this grinding problem was to determine which unit of the circuit was actually in trouble and to what extent. A series of tests conducted at a lower tonnage rate of rod mill feed indicated that one ball mill could grind satisfactorily at rates up to 70 gross tons of rod mill feed per hr.

Jan 12, 1957

By Eugene Sun, Qiang Xu

This presentation will review current applications of composite materials in aircraft design and discuss the challenges involved in maximizing the potential of the composites in aircraft applications.

Jan 1, 2010

By J Carrillo, A King

Gravity recoverable gold (GRG) is largely distinguished from other gold by its non-mineralised, metallic form, its high degree of liberation from the ore and its appreciable particle size. The gold mining industry has so widely accepted the use of batch centrifugal concentrators (BCC) and intensive cyanidation (IC) systems for the recovery of GRG that these may well be considered requirements of any plant processing ore containing appreciable GRG. The recovery of gold by gravity is quick, easy and cheap by comparison to alternatives. However, there are cases where attributes of the ore make recovery of gold by gravity and IC unusually challenging. This paper describes three examples where such challenges have been encountered and met, including those where the ore contains cyanide soluble base metals and where fine GRG is to be recovered from flotation concentrate.CITATION:King, A and Carrillo, J, 2018. Addressing challenging applications of intensive cyanidation in gravity gold recovery, in Proceedings 14th AusIMM Mill Operators' Conference 2018, pp 283–290 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 29, 2018

By Edward Halse

The occasional occurrence in metalliferous veins of rounded fragments of rock, matrix or ore, lying loose, embedded in clay, or enclosed in some kind of cement, may be attributed to four causes:— I. They have been washed in from the surface, or from an upper portion of the vein.. II. They are of concretionary origin. III. They have been produced by movements in the country-rock or in the walls of the vein. TV. They have been formed in situ, by the upward, downward or lateral flow of water in the vein itself. In this paper the word " conglomerate " is confined to a rock composed of rounded fragments or pebbles cemented together, as distinguished from a " breccia," in which the rock-fragments are angular. * I. Boulders and Pebbles which have been Washed in from the Surface, or from an Upper Portion of the Vein. In this type it is presupposed that the vein at one time communicated by a fissure or open space with the surface, or with the upper portion from whence the fragments have been washed. One well-authenticated occurrence was described long ago by Fournet. Owing, no doubt, to later dislocations in the lode, pebbles from an old alluvium and sands containing titaniferous iron, as well as fragments of wood, were found in a vein at Huelgoet, in France. " Toutes les parties tendres du filon de Pranal ou ces phenome'nes sont les plus prononces ont 6th excaves jusqu'a d'aasez grandes profondeurs par I' impetuosite des torrents, qui out depose la matiere alluviale.'"

Jan 1, 1906

By William H. Spice

The area on which oil and gas development is reported covers 30 counties, which are included in the Texas Railroad Commission's District No. I. This area not only includes the old established Balcones fault-line group of producing fields but also includes the southwest extension of this trend and some of the deeper Wilcox (Eocene) exploratory development. (Fig. J.) In the old Balcones fault-line zone, three new fields were discovered during 1941. These fields are comparatively small, producing from Dale limestone or Austin chalk. No new fields were discovered during the year in the Edwards (Lower Cretaceous) limestone horizon. One new shallow field was discovered in the Reklaw (Eocene) sand horizon and, in the southwestern part of the district, one oil field and one gas field were discovered in the Navarro (Upper Cretaceous) sand horizon. An extremely important extension was made to the one producing Wilcox (Eocene) field of the district in the Washburn Ranch field of La Salle County. The district produced 6,650,357 bbl. during 1941, which was a 12 per cent decrease under production for 1940. Approximately 4,954,000 bbl. of this total production was produced by the three Edwards limestone fields, Luling, Salt Flat and Darst Creek, the remaining production coming from the other 43 active fields in the district. In all, 3694 wells were producing at the end of 1941, compared with 3559 wells at the end of the previous year. During the year, 139 new producing wells were completed and 29 wells were abandoned in the producing fields. The increase in producing wells represents an increase in new wells over abandonments in these fields, together with a decrease in wells temporarily shut down as of the end of 1941. The majority of production drilling was carried on in the following fields; Bee Creek, Chicon Lake, Elm Creek, Gas Ridge, Pearsall and Tenney Creek. Approximately 250 wells were drilled during 1941, of which 110 were exploratory wells completed as failures throughout the district. Considerable exploratory work was continued during 1941 along the Wilcox trend. Geophysical work employing various types of geophysical methods and leasing activity was continued along this trend, particularly by the major companies. The significance of this activity is apparent from the successful extension and development in the Washburn field of La Salle County, where several well-developed gas-and-oil producing horizons have been developed in the lower Wilcox section between 5100 and 5600 ft. as noted in the following paragraphs. Continued exploratory activity along this general trend as far as present conditions will permit is predicted for 1942. New Fields Elgin Field, Bastrop County.—No. I-A Hiram Walker, Marts and Beaven, Inc., discovery well of the Elgin field, was com pleted on Apr. 22, 1941, in broken Austin chalk from 2820 to 2840 ft., pumping 105 bbl. per day, 36.8°A.P.I. gravity. The well apparently is producing from a crevice in

Jan 1, 1942

By William H. Spice

The area on which oil and gas development is reported covers 30 counties, which are included in the Texas Railroad Commission's District No. I. This area not only includes the old established Balcones fault-line group of producing fields but also includes the southwest extension of this trend and some of the deeper Wilcox (Eocene) exploratory development. (Fig. J.) In the old Balcones fault-line zone, three new fields were discovered during 1941. These fields are comparatively small, producing from Dale limestone or Austin chalk. No new fields were discovered during the year in the Edwards (Lower Cretaceous) limestone horizon. One new shallow field was discovered in the Reklaw (Eocene) sand horizon and, in the southwestern part of the district, one oil field and one gas field were discovered in the Navarro (Upper Cretaceous) sand horizon. An extremely important extension was made to the one producing Wilcox (Eocene) field of the district in the Washburn Ranch field of La Salle County. The district produced 6,650,357 bbl. during 1941, which was a 12 per cent decrease under production for 1940. Approximately 4,954,000 bbl. of this total production was produced by the three Edwards limestone fields, Luling, Salt Flat and Darst Creek, the remaining production coming from the other 43 active fields in the district. In all, 3694 wells were producing at the end of 1941, compared with 3559 wells at the end of the previous year. During the year, 139 new producing wells were completed and 29 wells were abandoned in the producing fields. The increase in producing wells represents an increase in new wells over abandonments in these fields, together with a decrease in wells temporarily shut down as of the end of 1941. The majority of production drilling was carried on in the following fields; Bee Creek, Chicon Lake, Elm Creek, Gas Ridge, Pearsall and Tenney Creek. Approximately 250 wells were drilled during 1941, of which 110 were exploratory wells completed as failures throughout the district. Considerable exploratory work was continued during 1941 along the Wilcox trend. Geophysical work employing various types of geophysical methods and leasing activity was continued along this trend, particularly by the major companies. The significance of this activity is apparent from the successful extension and development in the Washburn field of La Salle County, where several well-developed gas-and-oil producing horizons have been developed in the lower Wilcox section between 5100 and 5600 ft. as noted in the following paragraphs. Continued exploratory activity along this general trend as far as present conditions will permit is predicted for 1942. New Fields Elgin Field, Bastrop County.—No. I-A Hiram Walker, Marts and Beaven, Inc., discovery well of the Elgin field, was com pleted on Apr. 22, 1941, in broken Austin chalk from 2820 to 2840 ft., pumping 105 bbl. per day, 36.8°A.P.I. gravity. The well apparently is producing from a crevice in

Jan 1, 1942

The concept of æsustainabilityÆ can largely be defined as development that will not compromise the ælivabilityÆ of the planet for future generations. It has multiple dimensions, such as the triple bottom line û environmental, economic and social. And it also includes temporal (now and the future) and spatial (local and global) aspects that have to be taken into consideration to achieve true sustainability.Energy sustainability might be defined as û having the light turn on when you push the switch. It has, of course many more dimensions than this simplistic definition. Coal in Australia has an important role in keeping our lights on, but has its problems that need to be tackled head on to maintain a role in sustainable development.An overriding issue in terms of sustainability for coal is its major contribution to our greenhouse gas emissions. Whilst we have one of the most effective energy sectors in the developed world, based on well-managed, abundant fossil fuels, our greenhouse gas emissions are one of the highest per GDP in the developed world. We have to reduce our ægreenhouse gas signatureÆ.This paper explores the issues of coal utilisation greenhouse gas emissions as an indicator of the fuelÆs sustainability and the potential lower emissions pathways we will have to follow in a future carbon-constrained world.The technology changes will have significant implications for the minerals industry and it is argued that forward-looking coal/greenhouse emissions strategies need to be developed in alliance with the coal (and energy) sector for the minerals industry to maintain its global competitiveness.

Jan 1, 2004

By C. H. Jr. Herty

The results of a study of the open-hearth process from the physicochemical view-point are given. This study includes experimentation in small laboratory furnaces and in standard 100-ton furnaces. The behavior of manganese, carbon, and phosphorus are quantitatively explained. The action of "residual" manganese is discussed with reference to its relation to iron oxide dissolved in the metal. The solubility of CO in steel and its relation to dissolved FeO and carbon is given. The equation for phosphorus elimination has been tested out on a 200-ton furnace and the results are given in the text. THE effect of temperature and slag composition on the elimination of metalloids in the basic open-hearth process has been qualitatively understood since the early days of steel making. The quantitative effect has, however, only recently been brought to attention. The effect of slag composition has received more attention than that of temperature, primarily because the range of finishing temperatures in the basic open-hearth process is small compared to the large variations found in the composition of the slag at different periods during the process, and to the variations occurring with the use of raw materials of different degrees of impurity. The effect of slag composition on the elimination of metalloids has been studied by Styri1 from the thermochemical standpoint. This method is open to serious errors, in that thermochemical data at 2900° F. are very inaccurate and in many cases completely lacking. Feild2 has calculated equilibrium constants from the rate at which the metalloids are eliminated. The effect of slag viscosity on rate of elimination will affect the constants calculated by this method. Whitely,3 Colcough4 and others have used slag compositions as the basis for calculation of constants by which the extent of elimination may be calculated.

Jan 2, 1926

One of the major unknowns in the use of iron and copper is the quantity of various low level impurities, particularly hydrogen, that may be introduced during the deoxidizing process prior to casting. Introduction of hydrogen results in the embrittlement of components made from these metals. In addition, hydrogen bubbles in castings of copper result in the formation of blisters and swelling of the casting. During the last year, a significant effort has been made at the University of Missouri-Rolla to understand the permeation of hydrogen in galvanized automotive steel components and the hydrogen absorption during the electrodeposition of copper. The galvanized steel components consisted of automotive upholstery clips, seat belt holders and brake clips. Although the process of galvanization protects the steel from corrosion the process invariably causes the steel to pick up enough hydrogen to make it susceptible to brittle fracture.

Jan 1, 1992

By Dennis R. Dolinar, Eric R. Bauer

Skin failures of roof and rib in underground coal mines continue to be a significant safety hazard for mineworkers. Skin failures do not usually involve failure of the support systems, but result from rock or coal spalling from between the support elements. For instance, in 1997 more than 800 miners were injured by roof and rib falls, of which 98% were the result of skin failures [Bauer et al. 1999]. Also, nearly 80% of the roof and rib failure injuries occurred at or near the working faces in development sections. The face area is a zone where the potential for skin failure accidents and injuries and for roof and rib failures is high because of mining activity, ground readjustment due to changing stress conditions, and the higher exposure of mine workers. In addition, failures occur where the roof and rib are unsupported. This paper reviews the roof and rib accident statistics resulting from skin failure, and highlights the incidences by type, numbers and percentage, in-mine location, supported and unsupported roof, and worker activity at the time of injury. Also discussed are the causes of roof and rib skin failures, current and improved support methods and materials for skin surface control, and machine design modifications for improved roof bolter operator protection. It also reviews the historical literature on skin failures and control methods.

Jan 10, 2000

By V. R. Shea-Albin

This U.S. Bureau of Mines report discusses elastic wave velocity and attenuation behavior as an indicator for changes in load and structural integrity of coal samples. Measuring changes in compressional (P)-wave and shear (S)-wave attenuation and velocity under uniaxial and triaxial compression tests revealed their effectiveness for distinguishing changes in applied load and structural failure of samples. The velocity and attenuation values were used in further calculations such as ratios of P-wave to S-wave values, dynamic elastic constants, normalized velocities, and attenuation coefficients to reveal trends for loading and failure. The behavior of both P-wave and S-wave attenuation and velocity together define distinct and consistent phases of load change and failure for uniaxial and triaxial tests. The S-wave velocity and attenuation illustrate changing axial load and initial development of microfractures within the sample preceding structural failure more clearly than those of the P-wave. The attenuation and velocity ratios and dynamic elastic constants (except the bulk modulus) respond to closure of small preexisting fractures within the coal sample with initial loading to failure of coal samples. The attenuation coefficients and normalized velocities reveal trends similar to those shown by velocity and attenuation.

Jan 1, 2010

By A. D. Kalogeropoulos, T. N. Michalakopoulos

This paper deals with the numerical simulation of rock cutting laboratory tests using the discrete element method. The main objective is to provide a method for calibrating numerical DEM models of rock cutting in a systematic way so that realistic results are yielded. The numerical models are developed with the discrete element code Yade, which models rocks as a collection of bonded spheres. The models are calibrated in a four-step process based on the design of experiments method and optimization. The calibrated models are evaluated both quantitatively and qualitatively against actual laboratory cutting tests, in terms of the ratio of the simulated mean cutting force to the actual one and the cutting force time series, respectively. The fully calibrated models showed that the simulated cutting process matched qualitatively the actual cutting force recordings and underestimated the mean cutting force by approximately 3%. It is concluded that well-calibrated numerical simulations of the rock cutting process can provide not only a better understanding of the process itself but also quantitative data regarding the cutting force and energy requirements.

Dec 28, 2022

By C. W. JEFFERS

During the past few years the use of mechanical equipment for the loading and transportation of coal at the working face has rapidly increased . Many mining officials are of the opinion that mechanical methods have tended to reduce the hazards of mining, and a number of statements have been made to this effect . Little actual data upon which to base conclusions in regard to the relative safety of various methods of mining have been made available . While it may be possible that these systems of mechanical mining are inherently less hazardous , obvious dangers should not be disregarded in the belief that the mere act of installing mechanical loading equipment automatically brings about better accident records . The same rules and regulations , modified to meet the new regime must be applied with the same discipline as heretofore . By diligent study and application there is reason to believe that new methods of concentrated mining can be utilized with at least a possibility of increased accident performance . With the idea of preventing accidents by taking available precautions against their occurrence , attention should be directed to the dangers that exist where room and face conveyors are in operation . Due to the cost pressure prevalent in the mining industry at the present time mechanical means are often used in an attempt to decrease cost of production. The management , after having spent considerable sums of money for new equipment , is expected by stockholders and investors to show results by increasing tonnage and reducing operating costs . Consequently the operating officials apply the same pressure to local mine officials to obtain results . The natural reaction of the superintendent and mine foreman is to secure the maximum production from the new method , and unfortunately safety is frequently , if not generally , sacrificed to this end . In many instances , operators of new types of mechanical loaders are difficult to secure and after being obtained are difficult to hold , especially if the new equipment is more or less in the experimental stage . The tendency is to handle the machine operators with " gloved hands " and to permit many unsafe practices which ordinarily would not be allowed, in order to keep from antagonizing them and losing their services . Although these unsafe practices become habitual and even uneconomical , conditions thus established are difficult , sometimes impossible , to change .

Jul 1, 1930

By R. K. Koch

The normal spectral emissivities of liquid Ti, V, Zr, Mo, and Pt were determined at the fusion temperatures in an electron-beam furnace using a water-cooled copper hearth. The normal spectral emissivities were estimated above the melting points by using adjusted two-color temperatures as approximations of the true temperatures for substitution in Wien's equation. Simultaneous brightness temperatures were determined with a micro-optical pyrometer. The true temperature ranges covered were 1,668° to 1,885° C for Ti; 1,919° to 2,013° C for V; 1,855° to 2,367° C for Zr; 2,610° to 2,751° C for Mo, and 1,772° to 1,990° C for Pt. The spectral emissivities for titanium and zirconium decreased with increasing temperature. At an effective wavelength (?) of 658 mµ the emissivity of titanium ranged from 0.51 to 0.45 and zirconium, from 0.47 to 0.41. The emissivities of vanadium (? = 658 mµ) and molybdenum (? = 657 mµ) were constant at 0.41±0.02 and 0.33±0.01, respectively. The spectral emissivity of platinum (? = 658 mµ) was constant at 0.39±0.02 up to 1,900° C; above that temperature anomalous data were obtained. A mass spectrometric study indicated that platinum was reacting with back-streaming silicon vapors from the diffusion pump when the ambient pressure was greater than 2 X 10-5 torr.

Jan 1, 1973

By S. C. Suboleski

Forecasts indicate that the acid rain bill currently before Congress is likely to cause an increase in demand of 30 to 40 million tons per year of compliance quality coal from Central Appalachia. This represents a doubling of this segment of the coal business. This paper will examine how this doubling can be met, what the likely implications for pricing are, the major uncertainties associated with these predictions, and the likely outcomes of the growth in compliance coal. Finally, some implications for fuel planners will be discussed.

Jan 1, 1993

By Chingyuan Y. Li, C. Y. Hsieh

REALIZING that aluminum will have a great role to play in the coming industrialization of China, Chinese geologists have long been looking about for some aluminum deposits. The possible sources appear to be alunite, the alumina-rich shales, and the bauxite deposits. The locations of deposits are shown in Fig. I. ALUNITE Our attention was first directed to the alunite deposits along the southeastern coast of China. Table I summarizes the reserves now believed to exist in that region. [ ] Other alunite deposits have been found in Kiangpei, Szechuan province; Channing, Liuyang and Hsanshan, Hunnan province; Tsingchow and Chowyuan, Shantung province. No reserve figures are available. HIGH-ALUMINA SHALE Shale high enough in aluminum to serve as a source of that metal has been found in northeastern China (Table 2). [ ] In Manchuria, the Manchuria Light Metals Co., at Antung and Fushun, operating under Japanese control, has been the only active producer of aluminum. It is not known, however, whether the company uses local raw materials or imports ore from elsewhere.* SHANTUNG BAUXITE Bauxite was first recognized in China at Paoshan, Shantung province. Although the reserve is reported to be large (estimated at 271 million tons), the high content of insoluble residue (Si02) and mineral composition (diaspore) are dis-

Jan 1, 1946

By Zhao JC, Chen JJJ

A water/air model was developed to simulate the refining of molten aluminium by the sparging of gas through an impeller. The optimal gas dispersion depends upon selecting the correct gas rate for a given impeller rotational velocity to prevent flooding or channelling. Correlations illustrating this flooding behaviour exist for standard impellers within standard tank geometries. However the validity of these correlations has not been substantiated for gas dispersion in high temperature molten metals with non-standard tank and impeller dimensions.

Jan 1, 1995

By Raymond E. Kary, John W. Mcklveen

The four unit Cholla coal fired power station at Joseph City, Arizona, consumes coal from the McKinley mine located in western New Mexico. Since coals may contain relatively high uranium or thorium concentrations and may release quantities of detrimental progeny of these elements to the environs, there is concern that releases may pose an adverse environmental impact or even a health hazard to the workers. Thus, an effort was made to quantify the radionuclide content of the coal and compare the results with radionuclide concentrations already present in the vicinity of the plant. Additionally an attempt was made to assess any potential for significant enhancement of the levels of radioactivity in the environment or to plant personnel. Background gamma radiation measurements at and near the plant ranged from 8 to 12 [µ]R/hr (70 to 105 mR/yr) with a few localized anomolies measuring to 18 [u]R/hr (160 mR/yr). Levels on top of the coal storage piles decreased to ~ 6.5 [u]R/hr (60 mR/yr). Apparently the direct radiation emitted from the coal is less than the background levels in the vicinity of the plant. Measurements performed on top of several coal seams at the mine confirmed low radiation levels emanating from coal, but readings more than doubled when the overburden was monitored. Laboratory gamma spectrometry confirmed the lower amounts of natural radioactivity in the coal when compared against soil and water samples obtained in the vicinity of the plant and the overburden at the mine. In an effort to see if there is biological enhancement, animal feces was sampled. The radiation variations were found to be influenced primarily by naturally occurring potassium-40 which varied from ~ 1 to 18 pCi/gm rather than fluctuations in the uranium and thorium series. The potassium-40 concentrated in the ash were similar to the concentrations in the environs around the disposal ponds while Radium-226 concentrated in the fly ash was ~ 3 times that found in the immediate surroundings. Radon-222 gas concentrations in buildings at or near the plant ranged from 0.5 to 1.8 pCi/l and were generally lower than indoor concentrations measured in the Phoenix area. The burning of coal at the Cholla station does not appear to increase ambient levels of radioactivity found in the surrounding environs or to the workers. However, the use of byproduct fly ash for construction purposes may need to be examined.

Jan 1, 1981