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By Geo S. Rice

"The most authoritative compilations on the coal resources of the British Isles are given in ""The Coal Resources of the World"" issued by the 12th International Geological Congress, 1913. The reserve, calculated to a depth of 6,000 feet, in seams containing not less than two feet of merchantable coal are as follows: Mining at present is conducted at depths from about 800 to 3500 feet. The shallower coals have largely been exhausted. The present average hoisting depth probably is about 1500 feet.The thickness of individual beds at present mined varies from about 2-1/2 feet up to 40 feet in thickness, the latter thickness being found in North Staffordshire. The coal is rarely found level, but is approximately level in some parts of Yorkshire. Anthracite is mined in limited quantities in Wales, and Wales also produces a very high grade semi-anthracite or smokeless coal, which is fa famous the world round, and is equaled only by the Pocahontas and New River coals in the United States:As concerns the methods of mining, these vary widely according to the pitch of the bed, the thickness of coal, and natural conditions, but the prevailing method is some form of longwall or semi-longwall, by which all the coal is extracted. The other principal method is a so-called pillar and, stall method, by which the coal is mined out, leaving square or rectangular pillars which are extracted on the retreat, making it virtually, a retreating longwall system. This method is applied where the roof is strong, and particularly in the thicker beds, as the longwall method is not so well adapted for mining where the thickness exceeds five or six feet, unless it is what is called a multiple seam, one in which there are partings of rock that provide material for building walls, which the roof in subsiding gradually squeezes down."

Jul 1, 1920

By Alex C. Smith, Michael J. Sapko

A series of explosive detonation experiments was conducted in NIOSH’s Bruceton and Lake Lynn Experimental Mines to evaluate low level (<6 psig) detonation wave propagation behavior in single and multiple entry configurations. Entry cross-sectional area varied from 5 to140 m2 and explosive weights of Pentolite ranged from 0.24 to 2.4 kg. Behavior of the detonation wave was evaluated through recording of the pressure as a function of time and distance from the explosive detonation in single and multiple entry interconnecting tunnels. Peak pressure from detonation of an explosive in an underground mine maintains magnitude for a greater distance than is the case on the surface and is shown to follow the simple scaling rela-tionship P = 702.8(W/Vt)0.514(0.65)n, where P is the peak detonation pressure in kPa, W is the weight of the explosive charge in kg, Vt is the total volume in m3, and n is the number of splits, n = 0, 1, 2, …n. The total energy, or impulse, I, generated by these detonations can be expressed as I = 1.34(W/A)0.64n, where W is the weight of the explosive charge in kg, A is the area of the main tunnel in m2, and n is the number of side en-tries, n = 0, 1, 2, …n.

Until 1937, the mining of ore was carried out by conventional methods, using pneumatic drills and standard drill steel. The adoption of the diamond drill, formerly used for exploration work, for blast hole drilling in stopes, was first developed by Noranda Mines Limited, Noranda, Quebec, although it had been used previously in Northern Ontario and Western United States, to remove weak pillars and ore remnants left by conventional methods. Previous to the adoption of the diamond drill method at Noranda, a sub-level benching system of stoping was used. Sub-levels were driven at 35 ft. intervals and the benches drilled off by pneumatic drills using sectional steel. Results were very satisfactory, in sulphide ore, where the drilling was comparatively easy, but in the harder rhyolitestopes the footage drilled per machine-shift was only half of that obtained in the sulphide stopes, and owing to the high gauge loss, there was often difficulty in drilling holes to the required depth. This led to trials with the diamond drill for this type of work. While the cost per foot was more than with sectional steel, an appreciable saving in development work could be made by increasing the sublevel interval from 35 ft. to 60 ft., and stope widths from 60 to 100 ft. This saving, together with the increase in blasting efficiency, resulted in a substantial reduction in overall costs.CONDITIONS FOR SUCCESSFUL APPLICATIONWhile long diamond drill blast-hole mining has widespread application, there are certain conditions which appear to be desirable, if not absolutely necessary, for its successful use.

Jan 1, 1946

By Peter M. Anderson

IN recent years many prophets have arisen who hold that gold has outlived its days and that its monetary use is now an anachronism. These prophets include well-known politicians, economists and businessmen. Some of them have called it a joke that metal should be dug up at heavy cost in Africa and elsewhere and shipped to the United States of America only to go underground again at Fort Knox. Others have claimed that all the gold in the world could be sunk in the ocean without anyone being the poorer. The fact that you have invited me to address you on the future of gold may perhaps reflect the fears caused by these various predictions. At present the prophets&apos; taunts show no sign of coming true. The demand for gold is greater than ever before, although stocks held are the largest in history. Nearly all governments have gone to great lengths to suppress any demand that might be made by the public; they have reserved to themselves the right to hold gold and have lost no opportunity of satisfying their own demands. Where the public has been allowed to buy gold, the demand has proved impressively strong. In India the price of gold equals about $82 per fine ounce, having been $90 earlier in the year; in Egypt $65 to $70, after having been $87, and elsewhere it is even higher. In Palestine, for instance, the golden sovereign is traded at about £5, equivalent to $86 per fine ounce, having been nearly £6, equivalent to some $100 per fine ounce, earlier in

Jan 1, 1947

By W. Fourney

In the late 70’s and early 80’s in conjunction with other oil and gas well stimulation studies, personnel from the Dynamic Effects Lab performed model testing to demonstrate the effectiveness of utilizing an open section of borehole just before a plug. We called the process stem induced fracturing. The open section beneath the stem was used to increase the pressure magnitude and spread out the duration of the pressure pulse. This technique was later utilized to by Frank Chiapetta (1) in the fracture and fragmentation of rock in quarry blasting situations. He called his technique air deck blasting. In fact, Frank found that the Russians had previously discovered the same technique. There is currently interest in utilizing air deck blasting with an open section of hole beneath the explosive at the bottom of the bore hole to better remove the toe in a fragmentation shot. This paper reviews the development of stem induced fracturing and then describes a series of model tests conducted to measure borehole pressure at points along a borehole when an explosive charge is detonated at the midpoint of the borehole. Tests were conducted in both stiff boreholes (aluminum) and less rigid boreholes (PMMA-Plexiglas). Pressure time profiles were measured at the charge site, midway between the charge and the bottom of the hole, at the stemming at the top of the borehole, and at the bottom of the borehole. Crack initiation sites and crack propagation were also determined in the PMMA models. Some high speed pictures were taken of the event in the PMMA.

Jan 1, 2006

By Shane Andrews, Gustavo Vasquez, S. K. Varma

"The effect of solutionizing time on the corrosive wear behavior of 2014 aluminum alloy has been studied using the impact and continuous mode of scratching techniques. The transient currents (TC) evolved during the scratching of the alloy shows a linear dependence between the TC and the solutionizing time. Higher TC values at longer solutionizing time may be associated with the changes in the concentration of quenched-in vacancies, grain sizes and dislocations generated during scratching. These factors can either create (a) anodic sites or (b) pitting corrosion resulting in the generation of transient currents. The results have been compared with the similar study carried out for 6061 aluminum alloys. This 6061 aluminum alloy shows similar behavior but the rate of TC generation per unit solutionizing time is much lower than 2014 aluminum alloy. The morphological changes in the impact scratches and the TEM investigation in the scratch have been presented in this paper.IntroductionThe technique of studying corrosive wear of composites of 6061 aluminum in the monolithic and reinforced forms has been reported in the literature [1]. Two modes of scratching, consisting of impact and continuous, in a corrosive environment indicate that the composites, containing 0.10 and 0.20 volume fractions of alumina particles (VFAP), have higher corrosive wear rates than the monolith. A graph between the transient current (TC) generated during the impact scratching as a function of solutionizing time at 540°C indicates linear relationship between them. A similar slopes for the composites were observed and the TC values were less for the composite containing lesser VFAP."

Jan 1, 1998

By C. E. Reinhard

A USEFUL accelerated weathering test should be capable of placing any series of metals quantitatively in the same order of endurance as that noted under a particular set of actual exposure conditions. The development of such a test must necessarily depend to a considerable extent upon data obtained from a wide variety of exposures. This paper offers preliminary data from exposure tests on nine metals placed in 11 locations in the Lehigh Valley, within a radius of 20 miles from Palmerton. The exposure conditions vary from a severe industrial atmosphere to a pure rural atmosphere. The data are offered as evidence of the necessity for the identification and evaluation of the variables of corrosion and as illustration of some of the variations to be considered in the development of a useful accelerated test. It is quite clear, from this evidence, that a useful accelerated test must be versatile to the extent of showing the probable variations of corrosion resulting from differences in atmosphere as well as from differences in the metals. The paper is presented solely with the object of pointing out the wide variations in relative merits of several common metals in resisting corrosion and without any thought of initiating controversy regarding the, merits of particular metals. For this reason the metals are designated only by symbols in the tables and no key is given to these symbols.

Jan 1, 1929

By R. J. R. Cornelissen

The elimination of the incidence of silicosis in employees in industries such as mining and pottery is an ongoing international initiative. After many decades of industrial activity in these industries and many dollars spent on preventative measures, silicosis is still occurring. The exposure-prevention measures taken so far have certainly improved the working environment dust concentrations; however, the illness is still regularly diagnosed in workers. More funding is needed for interventions to improve working conditions. Many aspects of dust prevention and suppression will be researched and exposure assessment methodologies and equipment will need to be reviewed for the purposes of improvements in effectiveness. This paper presents results from laboratory tests carried out on gravimetric sampling pumps and cyclones. It highlights the erratic flow produced by gravimetric pumps of three different manufacturers who claim their respective pumps are equipped with flow stabilisers. The standard BS EN 1232:1997 is used as a basis for the tests. A method, albeit impractical for fieldwork, is shown for the elimination of the pulsation in the flow. This method serves to prove the method and protocol used in this study. The pressure loss caused air-flow resistance of cyclones is measured. The air inlet aperture size of cyclones is measured. The large discrepancy in the two criteria between individual cyclones is shown. The paper concludes that all the pumps tested failed the prescribed limits of BS EN 1232:1997 regarding the pulsation of the gravimetric sampling flow. The difference in flow characteristics of the cyclones, together with the erratic flow produced by the pumps, throws into question the accuracy of the exposure assessments. It is suggested that substantial resources be channelled towards solving these flow problems in parallel with measures taken to reduce exposure. In principle, the accurate assessment of exposure and dust concentration levels is a prerequisite for effective management of the problem of silicosis.

Jan 1, 2009

By Rudolph P. Frizzi

The current trend of increasing augered cast-in-place (ACIP) pile diameter, length, and load carrying capacities demonstrates improvements in installation equipment, increased acceptance, and that quality control is being successfully implemented by the parties involved in the ACIP pile construction process. Quality control is essential for ACEP piles since 24- to 36-in-dia (610-to 915-mm-dia) piles are currently being constructed to sustain design compressive loads of 800 to 900 kips (3555 to 4000 kN). This paper presents a summary of ACIP pile quality control procedures and methods beginning in the design and bid process, through ACIP pile installation, to post-construction. The results of a recent survey of contractors, engineers, equipment suppliers, and researchers routinely involved with ACIP piles in the United States, Europe, and the Middle East are included to address current trends in ACIP piles and quality control.

Jan 1, 2001

China has been producing gold for more than 4000 years with gold production increasing substantially since the 1980s, from about 25 tonnes in 1980 to some 160 tonnes in 1998. More than 80 per cent of the gold production is from East China. However, complete information on eastern China gold has been rarely reported internationally. This is a general overview on the tectonics and metallogeny of gold deposits in East China. The geology of these gold deposits is compiled mainly from data and information reported in China, and is also based on the authorÆs work in China from 1974 to 1986 and a recent visit to China.

Jan 1, 1999

By B. W. Firth

Increasing depth in vertical mine shafts penalises conventional hoists in at least four distinct ways: rope weight becomes limiting; travel time increases; the obstruction of ventilation becomes more serious; and with friction drives, rope wear due to torque is aggravated. Travel speed is limited by instability of poorly sprung conveyances on inaccurately aligned flexible rails, and also by the cost of installed power to meet an inherently peaky demand. These problems call for a review of existing designs, firstly in respect of the furniture (Buntons and guides) obstructing the air flow, and secondly in regard to the hoist running in the shaft.

Jan 1, 1969

By W. G. Woolnough

Production of oil in Australia is negligible at present. A very small quantity of crude is being recovered from lean pumpers in Victoria, and a little activity is evidenced in Queensland, where two new wells were sunk during 1934. One of these, at Warooby Creek near Roma, obtained a noteworthy gas flow, but no oil production has been recorded. Geological investigation is going on in Western Australia, but no drilling activity is apparent. The "boom" in oil prospecting came to an end when the wave of depression swept over the country, and the investing public turned its attention actively towards gold. There is great activity in gold prospecting at present. I still maintain as strongly as ever that the prospects of obtaining flow oil in Queensland, Western Australia and Victoria are good, and that really scientific methods must ultimately succeed. Active and excellent geological work is being carried out in the Mandated Territory of New Guinea, and it is reported that drilling is likely to be undertaken next year. Matters in Papua are at a standstill. The question of extraction of oil from the oil shales of New South Wales and Tasmania is perennially active, and attempts to exploit this source commercially are renewed from time to time. Hydrogenation of coal is also receiving a good deal of attention.

Jan 1, 1935

By Bruce A. Kennedy

The 1960&apos;s were an apparent turning point in the technological and social attitudes and awareness of the mining industry. From the late 19th century through to the early 20th century, one has always been presented with the picture of the rough and ready leaders of the mining industry who screamed for production and damned anything that got in the way of it. This attitude led to a certain alienation of the mining industry in the eyes of the general public. They saw an industry which was archaic in many of its practices and often heartless in its attitudes towards mankind. However, a gradual change spread through the industry and cracks began to appear in the hard facades of the mining companies. Resistance to change had almost become a standard operating procedure for many and consequently changes in technology had been slow in coming. The late 1950&apos;s and the 1960&apos;s saw a new awareness come into existence. As the mining company managements changed, there developed a realization that considerable efforts had to be made to bring the technology and social standing of the industry out of the dark ages and into the modern world. New advances were made in both metallurgical and mining technology. The 20th century technology of computers was accepted and became a standard tool of the industry.

Jan 1, 1971

By Liu Liu

In the recent 10 years the rapid development of Chinese steel industry has attracted the attention of the world. The technological progress of converter steelmaking has played an important role in this process. First of all, slag splashing has been extensively adopted by Chinese steel companies in various sizes of converters from largest to smallest ones, and even including those using special hot metal containing V and Ti. Remarkable metallurgical results have been achieved. Up to now the average converter campaign life has reached nearly 10,000 heats, and the longest exceeds 30,000 heats in three melt shops. Based on this process, the long-life combined-blowing converter steelmaking technology has been developed. Slag splashing has been used to form a gas permeable "slag mushroom" on the top of bottom nozzles to protect the nozzles. In order to keep the effective bottom blowing, furnace bottom thickness control technique has been developed to prevent the furnace bottom growth. It makes the service life of bottom nozzle the same as the converter campaign life (average 10,000 heats and longest > 30,000 heats). The complete combined blowing was ensured through out the furnace campaign. Concentration product [C][0] is in the range of 0.0023 ~ 0.0030%, the T.Fe in the slag is lowered by 4 ~ 6%, and the [0] in steel is decreased by 100 ~ 250 ppm.

Jan 1, 2004

By Chaves AP

This paper describes an investigation on the surface properties and mechanisms involved in the agglomeration of iron ore. For this purpose, an organic binder (carboxyl-methyl-cellulose (CMC)) was used in substitution of bentonite, the classic binder in iron ore concentrate agglomeration. Recently, a renewed interest of the iron ore producers in Brazil to replace bentonite for an organic binder, because of the economy that can be achieved in the, blast furnace operation. These savings are mainly due to the lower aluminum silicate addition which decreases slag volume and the improved pellet metallurgical properties which have the potential for lowering hot-metal production costs. Also organic binders are effective at lower addition levels, which results in lower storage and transportation costs. It is very important in Brazil because of the vast geographical area since transportation is made mainly by truck. Another advantage of organic binders is that they have low ash contents, and therefore most of the binders bum. off during the pellet firing operation. Previous studies have demonstrated the possibilities of the use of CIVIC, but in addition to its high cost, the pellets presented improper behavior at high temperatures or when prepared with high moisture levels. In the investigation here described, these problems have been solved through the addition of other reagents to CMC.

Jan 1, 1993

By Fabrizio Fara

The Ship Canal Water Quality Project (SCWQP) includes a 2.7-mile long, 18'-10" internal diameter tunnel which is located inWest Seattle. Tunneling in urban areas and soft ground conditions (Till and Till-like soils in Seattle) is associated with the risk of settlements, especially in presence of groundwater above the alignment. The Designer foresaw the use of soil improvement (jet grouting) outside of the launch shaft to mitigate the risk of flowing ground and to provide a redundant sealing. The Contractor proposed and ultimately successfully executed a different approach by using a “Steel Bell System” or Pressurized Can as described in this paper.

Jun 13, 2023

By D. Harrington, G. S. Rice, R. R. Sayers

"The Bureau of Mines in Serial No. 2606,4 issued in May, 1924, gave tentative specifications for rock-dusting to prevent coal-dust explosions in mines. Subsequently, a sectional committee of the American Engineering Standards Committee was appointed to formulate recommendations for standard practice in rock-dusting coal mines. The report of this Committee which follows was approved by the American Engineering Standards Committee, December 30, 1925. Several members of the Bureau of Mines staff served on this Sectional Committee and its recommendations are essentially in harmony with those of the Tentative Specifications in Serial No. 2606.As certain explanatory details contained in that serial are not included in the recommendations formulated by the American Engineering Standards Committee, it should be considered by coal-mine managements in conjunction with the committee's report which follows:Recommended American Practice for Rock-Dusting Coal Mines to Prevent Coal-Dust Explosions 1. Definitions of Terms Used: The term ""Mine"" shall include all underground excavations from which coal is hoisted or transported to the surface, through one or more openings.The term ""Main Haulage"" shall include all underground slopes and planes, all rock tunnels, and all entries excepting those from which rooms or chambers are turned.The term ""Entry"" shall include all underground haulageways, travellingways and airways, excepting working places as defined below:"

Mar 1, 1927

By M. Kataoka, Y. Obara

It is known that compressive strength and tensile strength of rocks vary significantly with specimen size. Rocks are composed of crystals and grains in a fabric that includes flaws such as microcracks, grain boundaries and pores. As the likelihood of including severer flaws becomes greater for a larger specimen, the strengths are small. On the other hand, the size effect in the fracture toughness of rocks has not been made clear until now because there are few studies focused on it. In this paper, Semi- Circular Bend (SCB) test was performed using Kimachi sandstone with various specimen sizes. A shape of the specimen is a semi-circular disc with an artificial notch. The specimens were prepared with various thickness t and radius r as the following two groups; t was changed from 10 to 37.5 mm with r = 37.5 mm in the specimen of group (a), and r was changed from 12.5 to 150 mm with t/r = 0.8 in the specimen of group (b). As a result, there was no significant change in the fracture toughness with different t. On the other hand, the fracture toughness increased with increasing r and converged on a certain constant value in a range larger than approximately 70 mm of r. Consequently it was clear that the size effect in the fracture toughness of the sandstone exists.

Jan 1, 2015

By Ludovico Sebastiao Costa, Luis Albano Tondo, Bonzi Yokomizo Santos, Nelson Roberto Garcia Munhoz

This paper focus on the productivity, cost efficiency and training programmes that have enable RPM to rank as a world class operation in production efficiency and safety achievements. The first step was to commit all senior managers to implementing the NOSA Industrial Safety System based on Management by Objectives. This focused the workforce in a specific, results-driven direction which greatly promoted subsequent performance improvements. The early operations concentrated on increasing throughput via process simplification and removal of bottlenecks. Efforts were simultaneously directed to environment, health and safety as a means to improving the quality of operations. In the last two years, improvements in mining and in-tailings dam management have further improved the cost competitiveness of RPM such as to assure its future in treating the remaining CTBl ore reserves. Promissing progress is being made in developing a viable process to exploit a remaining large resource of B2 mineralisation.

Jan 1, 1993

By A. J. Phillips, C. H. Mathewson

BERYLLIUM, magnesium, zinc and cadmium, together with mercury, constitute a coherent sub-group of the periodic system and these metals, excepting mercury, have been studied in sufficient detail by the new X-ray diffraction methods to prove their common adherence to the hexagonal close-packed type of crystal structure with a progressive increase in axial ratio as we pass through the group from beryllium to cadmium. The first four columns of Table 1 summarize the data on crystal structure of these metals reported in the International Critical Tables.1 The last two columns are based on results obtained in the present investigation. [ ] Twinning has often been observed in zinc and cadmium. The general aspects of this twinning are abundantly illustrated by photomicrographs, diagrams, etc., in the papers by Romig, and Mathewson and Phillips reported to this Institute in 1927.2 A determination of the composition

Jan 1, 1928