Search Documents

By C. Guney Olgun, Mohammad Khosravi, Daniel W. Wilson, Deepak Rayamajhi, Scott A. Ashford, Shuji Tamura, Ross W. Boulanger

"Dynamic centrifuge tests were performed on unimproved and improved soil with soil-cement column models. The reinforcing effect of isolated soil-cement columns for reducing liquefaction potential and ground deformation in improved soil were investigated. This paper presents the observed acceleration, pore pressure, and settlement responses under an earthquake base motion for both unimproved and improved soil models. In addition, lateral reinforcing effects of soil-cement columns were also investigated in terms of site stiffening effects and the increasing natural frequency of improved soil. The test results show that the soil-cement columns were rather ineffective in preventing liquefaction triggering in improved soil and in significantly reducing the magnitude of the resulting soil settlement compared to the model with unimproved soil profile. Furthermore, the predicted natural frequency of the improved soil profile estimated using existing design equations is shown to be significantly higher than the observed natural frequency inferred from centrifuge tests results. These design equations assume shear strain compatibility between the columns and the surrounding soil. On the other hand, revised design equations that account for shear strain incompatibility between column and surrounding soil are shown to give reasonable estimates compared to the observed natural frequency of the improved soil model.INTRODUCTIONGround improvement using stiff columns (e.g., stone columns, deep-soil-mixing columns, and jet-grout columns), are often used in practice to reduce liquefaction potential (and associated deformations) in loose soil sites. Typically, saturated silty soils are difficult to densify or drain rapidly due to their lower hydraulic conductivity, so densification and drainage techniques of improvement are often found to be ineffective. Instead, the shear reinforcing mechanisms of stiff columns are considered effective for reducing the seismic stresses and strains, and thereby reducing liquefaction potential in the enclosed saturated silty soils (Baez 1995, Adalier and Elgamal 2004, Mitchell 2008)."

Jan 1, 2015

By Thomas V. Falkie, Robert Stefanko

Previous articles in this column have defined the manpower situation as it. applies to the coal industry. There is at present a shortage of experienced managers, mining engineers, technicians and skilled workers. The extent of this shortage is controversial, but it is sufficiently important to have received the serious attention of coal industry people at all levels. It has also been discussed by union officials, educators, government agencies and trade publications as well as other communications media. Discussion is not enough, however. A plan of action is needed. Some suggestions for such a plan are presented here. First, the coal industry must interest itself in government training programs. The U.S. Government (primarily the Bureau of Mines and HEW) is planning to spend or is spending millions of dollars to educate and train technicians, inspectors, engineers and miners. The new Federal Health and Safety Academy at Beckley, W. Va., for example, will involve an expenditure of $20-30 million for the physical plant alone. There are encouraging signs that the present hierarchy in the Bureau of Mines intends to seek the advice of mining educators on some of these projects, but industry should also demand a voice in the policy to be followed in making these expenditures.

Jan 1, 1971

By R. Ciccu, P. P. Manca, A. Bortolussi, G. Massacci

Tool performance and the unit cost of cutting depend on a number of operational variables (peripheral velocity, pull-back force, water injection rate, angles of the sections of wire outside the rock) as well as on the geometric features of the cut itself (area and shape). Cutting rate and wire productivity are also influenced by the type and number of diamond beads per unit length of wire and by the characteristics of the rock (granite or marble). A computer program aimed at handling a problem of this complexity has been developed and tested with the use of available field and laboratory data and has been found acceptably reliable. Discrepancies between current industrial data and some of the results suggest future lines of research, while the simulation should also be extended to include different types of rock and tool and a variety of bench face geometries

Aug 1, 1994

By John B. Gayle

The coking time has considerable influence on the throughput of a coke oven, and for this reason a large number of papers dealing with the relationship between coking time and the different operating variables have been published. Although all factors known to influence the coking time have been studied, agreement has not been reached on several questions.2/3 Therefore, it appears worthwhile to evaluate any data that become available during investigations of the carbonizing properties of various coals and coal blends. Because it is expected that reports covering several different phases of this problem will be forthcoming as additional data-become available, the following study of the relationship between coking time and bulk density represents a report of progress on the overall investigation of factors influencing the coking time in slot-type ovens. The practice of including coarse coal in the blend going to the ovens to obtain increased bulk densities is well known. Similar increases have been realized by adding small quantities of oil to the coal mix. Although it would appear that such procedures provide inexpensive methods for increasing the capacity of existing coke-oven installations, Ramsburg and McGurl4/ point out that this increase is possible only if the additional coal can be carbonized in the same coking time as regularly employed without using abnormally high flue temperatures. This statement is in substantial-agreement with the position of Auvil and others5/ and implies that any change in bulk density may be accompanied by a corresponding change in coking time. On the other hand, a recent review of proposed methods for calculating the time required for carbonization6/ includes a number of equations that completely ignore the effects of variations in bulk density.

Jan 1, 1954

By Paul Krivokuca

Outline Quinsam Coal Mine ?? Location ?? Mine History ?? Safety ?? Production ?? Hiring 4S Mine ?? Depillaring design ?? Structural mapping, Risk assessment ?? Rock Bolt Design Selection ?? Training

May 1, 2008

Exerting the Advantages of National Key Discipline, Outstanding the Training of Engineering Capability, Cultivating Talent to be with Innovation Ability

Sep 13, 2010

By James L. Evers

Introduction There is a continuing search by government and industry for new mining methods that increase production, improve the working environment, reduce labor intensity, enhance recovery effectiveness, improve the reclamation process, streamline the flow of material, and reduce the unit cost. Hydraulic extraction and transport methods have outstanding potential in several of these areas. For example, hydraulic fragmentation produces a significant reduction in respirable dust. The inherent simplicity of hydraulic mining equipment and the resulting high reliability are recognized. Tool wear can be virtually eliminated. There is great flexibility in the size, shape, and orientation of the mineral deposit that can be mined. The cutting, gathering, and transport operation can be controlled remotely, providing more safety for workers. The threat of tool sparking and the resuiting dust or gas ignition are also eliminated. Although hydraulic mining was introduced in the US before the turn of the century, it has not gained the degree of acceptance found in other countries such as the Soviet Union, China, Germany, and Canada. The Hydraulic Mining Research program, initiated by the US Bureau of Mines in 1958, and the subsequent research by others has provided much of the basic technology required to spur the development of these methods into a viable extraction alternative. This article updates the development of hydraulic mining in the US. Particular attention is paid to monitor mining, the long-wall hydrominer, borehole mining, and the semi-autonomous mining system. Whenever the particular mining method is also being developed in other parts of the world, a brief description of the world-wide state of the art is given. Finally, allied studies designed to optimize these mining techniques are described. Hydraulic Monitor Mining Since 1958, the US Bureau of Mines (USBM), the Department of Energy (DOE), and other government agencies have funded more than a dozen programs to investigate the potential of hydraulic monitor mining. For this method, water is directed on the coal face from a monitor nozzle. Sufficient velocity is used to cause local fragmentation (Fig. 1). Coal particles are washed from the face to a trough. They are then flumed to a collection point. Oversized particles are directed through a breaker and then into the troughs. Monitor field tests were conducted in the 1960s in bituminous and anthracite coal at the following locations: • Rosylin No. 9 mine, WA (Nasiatka and Badda, 1963); • Rosylin No. 10 mine, WA (Price and Badda, 1965); • Sugar Notch mine, PA (Buch, 1964); • Thomson Creek mine, CO (Palowitch and Malinka, 1964); and • West Lebanon, PA (Fowkes and Wallace, 1968). In 1975, Ingersoll-Rand Research Inc. was awarded a two-year USBM contract to develop a continuous coal mining system using water jet fragmentation and

Jan 10, 1984

Marketing of mineral products has not yet succumbed to the degree of pre- dictability and exactitude that is fam- iliar to the engineer or metallurgist in pursuing their profession. Whilst the Great Market of the world economy dic- tates circumstances for the sale of min- eral products, there are more than just buyers and sellers in the determination of the revenue received by the producer. For the engineer or metallurgist he will be required to gain an understanding of these participants and of the peculiar languages of the market place. This will be only one of his tasks in learn- ing to communicate with society, as his responsibilities increase as he climbs the ladder of success. There is un- doubtedly a need for better statistical information so that producers and sell- ers can make an appropriate and earlier response to market conditions. There is in addition, a need for more aggressive concern by raw material producers for the development and promotion of better end use of their products. Undoubtedly the marketing of mineral products will be more influenced by the direct involv- ment of government agencies than has been the case in the past. Whilst that 1. Director - Marketing & Finance, North Broken Hill Limited.

Jan 1, 1975

WILLIAM YOUNG WESTERVELT, Chairman, Representing A. T. M. E. and M. and M. Soc. of Am. ALFRED G. WHITE, Secretary, Representing U. S. Bureau of Mines. W. 0. HOTCHKISS, Representing Association of American State Geologists. DAVID WHITE, Representing U. S. Geological Survey. The organization and purpose of the War Minerals Committee was explained in a special war notice in the-August Bulletin. The first work of this Committee is to secure and condense information as to the relative importance of different properties from the standpoint of domestic mineral production. When the possibilities of ore deposits are known, involving, in some cases, further examination through the voluntary services of, Engineers and Geologists, then the necessary policy required to stimulate such development can be determined. Proper recommendation has been and will be made to .the various agencies controlling the situation during the war. This will insure a complete presentation of the needs of the situation. Every legitimate effort will be made to stimulate the production of domestic minerals and to put the industries on a permanent basis. The following information forms indicate the type of information required by the Committee. Engineers and Geologists can assist in one of several ways in furnishing information to the War Minerals Committee:

Jan 10, 1917

By Trevor Saldanha, Nawshad Haque, Will Sikora

This study reported life cycle assessment (LCA) of six copper mines in Australia, Papua New Guinea and Portugal. Inventory data was sourced from published papers, sustainability reports by mining companies, independent technical reports and previous CSIRO studies. Sima Pro software and various databases were used to evaluate life cycle based environmental impacts. The impact indicators were: global warming potential (GWP), acidification potential, water footprint, ecotoxicity potential, ozone depletion potential and human toxicity potential (carcinogenic and non-carcinogenic), abiotic resource depletion potential (minerals and fossil fuels), particulate matter and ionizing radiation. Generally, open pit mines were found to have a GWP of approximately 1.0 t CO2-eq/t Cu concentrate while underground mines had approximately 1.3 to 1.8 t CO2-eq/t Cu concentrate. Environmental impacts varied between mines considerably due to several factors, most notably: ore grade, mining method, flowsheets and ore mineralogy. Energy consumption and sources were significant contributors to most impact categories.

Mar 1, 2018

By R. G. Davies

WeERTMANI has shown that the high temperature steady state creep rate, i, in lead and indium-base alloys obeys an equation of the form where AH is the activation energy, o the applied stress, n the stress exponent, and R and T have their usual meanings. He observed a variation in n from 4.5 for pure metals to 3 for concentrated alloys, which he interpreted as due to Change in creep mechanism from the climb of dislocations in pure metals to a micro-creep mechanism in the alloys. The Cottrell-Jaswon microcreep mechanism of the moving dislocation taking its impurity atmosphere with it was considered to be the most likely process, although short-range order and the segregation of solute atoms to a stacking fault will also give a stress exponent of 3. Steady state creep has been investigated in a Au - 27 at. pct Cu alloy at temperatures above 1/2 TIM where TIM the absolute melting temperature. As the oxidation resistance of this alloy is excellent all tests were carried out in air with a furnace built to give a temperature variation of less than 1°C along the 60 mm gage length. A lever-arm arrangement applied the stress with a load being adjusted between each creep test to maintain a constant stress. As each test produced less than 0.5 pct creep strain, the variation in stress during the test was negligible. The creep strain was measured by a transducer at the end of one of the alloy-steel grips, with the out of balance potential being finally recorded on a variable speed chart recorder. A typical creep curve is shown in Fig. 1. The results, Fig. 2, confirm that n is nearer to 3 than to 4.5; the creep mechanism could be any of those given above. The activation energy, AH, which is independent of stress, is consistent with a diffusion controlled process; the activation energies for the self-diffusion of gold and for the diffusion of gold into Copper are both -45 kcal per ml., There is now considerable evidence, that, when the steady state creep is dependent upon diffusion, irrespective of the actual creep mechanism, the activation energy is independent of the stress. The author would like to acknowledge the financial assistance provided by the International Atomic Energy Agency, Vienna, and the Argentine Atomic Energy Commission.

Jan 1, 1962

By N. A. Sithole, S. A. C. Hockaday, P. J. A. Bezuidenhout

The Northern Cape Province in South Africa has high levels of annual direct normal solar irradiance and reserves of zinc (Zn) ores. The question arises as to the benefits of integrating renewable solar energy into the beneficiation routes of these reserves. The paper evaluates a novel flowsheet for the production and beneficiation of Zn in this region, maximising localised solar energy as a source for both electricity and process heat. Solar variability is discussed and the cost and benefits of thermal storage in the flowsheets are evaluated by its influence on the levelised costs of electricity and process energy over the project life-time at a possible implementation site. The results of the developed scoping model showed that solar photovoltaic integration to provide electricity for electrowinning without battery storage can lead to more than 10% cost saving on electricity over the lifetime of the project. Additional savings potential was identified when battery storage was included to enable the solar PV system to supply electricity during peak tariff periods. The solar thermal case showed the most promise with savings of 70% on heating costs for casting, while solar PV electricity without storage resulted in a 16% cost saving on heating for casting over the lifetime of the project. Solar PV electricity generation resulted in the avoidance of more than 20% of CO2 emissions from grid electricity use. Solar thermal heating can avoid up to 80% of the CO2 emissions associated with grid electricity use for remelting of Zn cathodes for casting. The CO2 emissions are indirect and not subject to South African carbon tax. Keywords: Solar process energy, zinc beneficiation, flowsheet evaluation

Jan 1, 2020

The Johns Hopkins Press, Johns Hopkins University, Baltimore, Md The Johns Hopkins Press has issued a number of books as The Johns Hopkins University Studies in Geology Five of the studies are paleontological in character; five are on geology: No. 1, The geology of the Corocoro copper district of Bolivia, by J. T Singewald, Jr and E W. Berry, $1 50, 2, The geology and paleontology of the Huancavehca mercury district, by E W Berry and J T Singewald, Jr $1 50, 6, Contributions to the geology and paleontology of South America, by E W. Berry and F M Swartz, 3175, 7, The geology of the Island of Trinidad, B W I, by G A Waring, with notes on the paleontology by G. D Harris, $1 75, 8, Fifty years' progress in geology, 1876-1926 Papers presented at the Geological Conference during the 50th Anniversary of the Johns Hopkins University, $1 50 An additional publication on geology is. Notes on the minerals occurring in the neighborhood of Baltimore, by G H Williams, 25 cents. In the list of Doctors' Dissertations available from the University are found all theses on geology and mineralogy, about 90 in number, from 1886 on Authors of many of these have since made great names for themselves in the fields of geology and mineralogy. Most of the theses have been published as papers by other agencies and, as such, will be found under other headings in this directory

Jan 1, 1933

Discussion of the paper of EDWARD G. NORTON, presented at the New York meeting, February, 1915, and printed in Bulletin No. 97, January, 1915, pp. 93 to 102. G. D. HARRIS, Ithaca, N. Y. (communication to the Secretary *).¬Since I have on several occasions1 expressed at length my general views on this interesting subject, it seems fitting that I endeavor here to comment as briefly as possible on a few points suggested by the paper. Doubtless you all know of the rather extensive publications of Lachmann on mid-European salines and his scarcely successful, attempt to make the phenomena presented by our domes fit. into his "Exzeme" theory based on studies of European phenomena. This paper is a most welcome indication that scientific America is very much alive to the difficulties that have been encountered in attempts already made to explain the origin of the salt domes in the lower Mississippi embayment region. Praiseworthy, too, is the attempt to explain these phenomena by agencies still in operation. I may, perhaps, be permitted to state here that a former student of mine, and co-worker in Louisiana, A. C. Veatch, is now interested in the Algerian region, where it would seem similar dome-phenomena are to be found, and hopes may well

Jan 5, 1915

Recovery Process of Carbon Dioxide with Metal Oxides and Metal Hydroxides

Sep 13, 2010

By H R. Phillips

Fresh air intake in an underground coal mine is of critical importance to the occupational health and safety of workers due to the dynamic, confined and dangerous nature of the mining environment. In most coal mines in South Africa, belt road is not separated from the fresh air intake to the sections. Intake air to coal production faces generally contains dust generated by conveyor belts, transfer points and travelling roads. Long roadways (up to a few kilometres in some of the existing mines) to the coal sections are involved in the ventilation circuits of individual sections. This leads to a progressive increase in the dust levels in the intake fresh air and thus high dust levels in the air delivered to the working sections downstream. In the process of reducing worker exposure to dust in the face area, attention to the monitoring of fresh intake air is generally given a low priority. This paper summarises the intake dust levels measured in selected South African underground coal mining sections over the past five years and its use as a parameter in assessing worker exposure to dust through a newly developed model called the Dust Exposure Level Index (DELI). Based on the measured data of the South African coal mines, the average section intake dust level was 0.78 mg/m3. Approximately 60 per cent of the samples collected for the study have exceeded the 0.5 mg/m3. The intake dust level measured at a longwall face was much higher than in the CM headings. The measured section intake dust levels furnish the South African coal mining industry with the latest depiction of the level of face area dust contamination due to the intake air. Further, this paper demonstrates the use of intake dust level as a parameter in estimating exposure levels of workers, as it clearly plays as a corner stone in effective control of exposure to face area respirable dust. It must be borne in mind that intake dust is a base level to the mine worker exposed to dust without carrying out any additional work in the section. If the intake air is seriously contaminated by airborne respirable dust; then the exposure of the workforce in the section will constantly be elevated by that background dust level.

Jan 1, 2005

By R. S. Shoemaker, F. W. McQuiston

ECOLOGICAL CONSIDERATIONS IN CYANIDATION PLANT PRACTICES Ecological controls of tailing storage pond effluents are mainly concerned with mercury and residual cyanide and are critical problems for gold and silver recovery plant operators. For example, mercury for direct amalgamation of gold ore was used at Homestake until 1970 when the Federal Government acted to prevent further use thereby forcing the abandonment of this practice. However, mercury is still used at Homestake, in South Africa, and also in some Philippine and Canadian cyanide plants for barrel amalgamation of free gold gravity concentrates. The amount of mercury involved in South African practice is about 150 ounces for every 100,000 tons of ore milled and which reaches the tailings ponds. In South Africa, it is obligatory that no pond effluent be discharged beyond the mining property boundaries and waters containing mercury and cyanide must be evaporated either on the tailings pond or in specially constructed evaporation dams. In some cyanide plants such as Carlin and Cortez in the United States, all supernatant solution from the tailings ponds are returned to the plant for reuse. When all solution cannot be reused, the excess may be evaporated in shallow ponds, or by spray systems inside of the tailings dam. Such plant reuse of tailings effluent depends strictly upon the degree of contamination or "fouling" of the barren solution and tailing water with cyanicides. Foul solutions that cannot be returned from the tailings pond may be effectively cleaned up by cyanide regeneration. Cyanogens in plant solutions exist chiefly as free alkali cyanides, as zinc and copper double cyanides, as sulphocyanides, and as ferrocyanides. From the free cyanides and zinc double cyanides, substantially complete recovery of the cyanogen is easily effected. Part of the cyanogen combined with copper is also recovered; regeneration of the remainder with the cyanogen existing as sulphocyanide and ferrocyanides requires special treatment. At this stage, it would be generally more practical to eliminate the remaining cyanogen by chlorination. Ecologists have also been concerned with pollution of ground waters from cyanidation plant tailings. An accute problem is solution seepage down stream from tailings dams and strict attention to prevent or collect any seepage is a real necessity. The tolerance levels of the total cyanide content in potable water set by several U. S. and State health agencies are 10 ppb, and 20 ppb discharged into ground waters. The cyanide content so established is, strangely enough, based on the survival tolerance of fingerling trout. Decanted waste water from tailings dams may be effectively treated by the use of alkaline chlorination for the purpose of destroying all cyanide compounds. The alkaline hypochlorite used to oxidize the cyanide to cyanate is applied as such or generated within the waste solution by adding caustic (NaOH) and chlorine gas. A second chemical reaction involves complete destruction of the sodium cyanate.

Jan 1, 1975

By William S. Butcher

Research and development of tunneling technology is rapidly taking its rightful place as an important ingredient in the Nation's research and development strategy. The state of technology in tunneling is very important to the Federal Government. Through its support, both direct and indirect, of a wide range of public works, our government, using the taxpayer's money, is the biggest buyer of tunnels. So that this money is spent wisely and efficiently, it is important that potential developments in tunneling technology that promise lower cost tunnels be pursued, if the cost of reaching the goals is commensurate with the prospective benefits. For too many years, the Federal Government's activities in the tunneling technology field were fragmented. Recently, specific coordination efforts have been initiated. It may surprise some to realize that the total Federal expenditure on excavation technology research and development, which is largely devoted to underground excavation, is growing by leaps and bounds. In fiscal year 1971 alone, approximately $19 million were expended by Federal agencies. This current fiscal year (FY 1972) that amount will increase to $24 million. It would appear that next year we will exceed the 1972 expenditure by 52 percent to bring the total FY 1973 expenditure up to $36 million. As most of this money is devoted to underground excavation, it is clear that the Federal Government

Jan 1, 1997

By Dalene Joalet Steenkamp

Excavation of industrial-scale furnaces allows for the systematic study of reaction sequences by identifying the different reaction zones within the furnace. In 2013, Transalloys excavated a 48 MVA submerged arc furnace that was used for silicomanganese production using the ore-based route. The excavation method was reported elsewhere as was observations made in terms of refractory wear and modes of electrical energy dissipation prior to excavation. The paper presented here, reports on the process reaction zones observed during the excavation and subsequent phase chemical analyses of a number of process samples obtained during the excavation. The zones identified were a loose burden zone, a dry coke-bed zone, a wet coke-bed zone, a hard build-up zone, and an alloy zone. The results are compared to observations made in the excavation of an industrial-scale SAF and a pilot-scale SAF in Norway. The presence of the hard build-up zone below one of the electrodes and absence of a slag zone below all three electrodes are unique features of the SAF excavated at Transalloys.

By H. I. Smith

THE recently developed potash industry in southeastern New Mexico, though based on a relatively new discovery, marks the latest and perhaps culminating phase of the effort to obtain a domestic source of potash that began with the leaching of wood ashes more than 300 years ago. In the search for mineral potash in America, the Geological Survey has played a conspicuous part and has paved the way for much of the private activity that now bids fair to free the nation of foreign domina¬tion in supplying the nation's potash requirements. HISTORICAL REVIEW A pamphlet published by Thomas Stephen in 1758 pictures the industry in its early struggling condition.1 Just before the Civil War, a deposit of mineral potash had been found in Germany and its value as a fertilizer had been discovered. On this account and because the supply of wood ashes had decreased, the Ameri-can potash industry gradually lost its importance. During the next 50 years, with European potash available with little effort and with satisfactory substitutes on the market for the manufacture of soap, the interest of the American people in American potash declined. In 1910 this interest was suddenly revived by the abrogation of American potash contracts in Europe. Congress passed an act, approved by President Taft March 4, 1911, providing for "researches with a view to determining geological conditions favorable to the presence of deposits of potash salts." Appropriations were made to the Geological Survey and the Bureau of Soils to carry out the provisions of this act. The work of the Survey was directed toward the finding of commercial bodies of natural soluble potash salts; the Bureau of Soils was more concerned with the processes of extracting potash from industrial wastes and organic sources. Private agencies also became interested in the program. The Geological Survey has continued its search throughout the ensuing period of more than 20 years and has studied many types of deposits in many parts of the country.

Jan 1, 1933