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By Sara J. Davenport

Hydrogen sulfite has been listed (1)3/ as a possible hazard in 50 occupations, many of which are in the mineral industries. The effects of its occurrence in the petroleum industry made themselves felt more than two decades ago, resulting in a comprehensive study (2) of the toxic gases from Mexican and other high-sulfur petroleum products. The mining industry, likewise, has had cause to guard against this gas. Enough hydrogen sulfide has been found in coal and some noncoal mines during normal operations to cause severe eye irritation, some serious illness, end even fatalities. It is usually a product of the decomposition of sulfur compounds and may be produced by burning explosives containing sulfur; the gas in harmful qauntities is formed by the use of block blasting powder or by the use of dynamite in blasting sulfide ores. Hydrogen sulfide is readily soluble in water, and enough may be released from water streams in coal and noncoal mining to cause fatal poisoning it is found sometimes in stagnant water underground, particularly where ventilation currents are absent, and great care must be exercised when accumulations of such waters are disturbed, as exposure to comparatively low concentrations of the gas evolved therefrom has caused fatal accidents.

Jan 1, 1945

By Louis G. Bailey

This paper .reviews some of the key developments which have been made in the synthesis of the III-V compound semiconductors and the associated progress in obtaining high-quality material for device development. The history of the investigation of the semi-conducting properties of these materials has indicated the need for synthesis techniques capable of producing rnaterial of high chemical purity and physical perfection. The progress in the area is described, and the present status of quality of several compounds is discussed. In addition, recent studies of localized epitaxial deposition of GaAs into semi-insulating GaAs substvates for the development of arrays of devices ave reviewed. In conclusion, some important areas for future research and developrnent are discussed. INTEREST in III-V compounds as semiconductors dates back to the period 1950 to 1952, when Goryunova, Ioffe, and, in particular, Welker determined that 111-V compounds were structural analogs of the group IV elements carbon, silicon, germanium, and tin and that they were also semiconductors.'-3 Since that time interest in the properties of these materials has ex- panded rapidly. During 1953 and 1954, the first reports of rectification, photoconductivity, and optical absorption in these materials came from several investigators. In 1955, recombination radiation from samples of GaAs, InP, and GaSb was reported by ~raunstein .' This radiation was produced by injected minority carriers from point and large-area contacts. From 1955 to 1960, efforts increased on preparing large, pure specimens of these materials for the study of basic physical phenomena and device exploration. By 1960, materials preparation and the understanding of the physics of some of the materials had advanced to where some very interesting and potentially useful phenomena came under study. The first observation of electric-field-induced changes in the optical absorption edge (Franz -Keldysh effect) of 111-V compounds was reported for GaAs by Moss in 1961.' In 1962 the study of recombination radiation advanced rapidly. Keyes and Quist6 and Pankove and Berkey-heiser7 reported high radiative efficientices obtained from recombination, and then the first injection electroluminescent lasers in GaAs were announced by Hall ef al.,' by Nathan et al.,O and by Quist ef al.,'O and in Ga(As, P) alloys by Holonyak and Bevacqua." Hil-sum has reviewed the early work leading to the first observations of laser action in GaAS." Recombination processes in GaAs, Gap, and the other 111-V com-

Jan 1, 1968

By Geoffrey Gilbert

Rossland is in the West Kootenay district; 5 miles north of the International boundary and 4 miles west of Columbia River at Trail. The first claim in the district was located in 1887; but there was little activity until 1890; when the showings that later became important were staked and development began. Production increased rapidly from 1; 800 tons in 1894 to a peak of 360; 000 tons in 1903; and averaged 286; 000 tons for the next 13 years. It declined sharply in 1917; and continued to decline until the closing of the main mines in 1928. Between 1933 and 1941 leasers mined a further 137; 000 tons. Total output has been about 6; 200; 000 tons; with average recovery of 0.47 oz. gold; 0.6 oz. silver; and 1 per cent copper. The total value was $82; 500; 000; of which aboµt three-quarters was in gold; the camp still leads the province in total gold produced. Ninety-eight per cent of the tonnage came from a small compact area worked by four inter-connected mines : the Le Roi (39 per cent); Centre Star (25 per cent); War Eagle (24 per cent); and Josie (10 per cent); all now owned by the Consolidated Mining and Smdting Company of Canada; Limited.

Jan 1, 1954

By E. J. Gleim

[of- ac tore affecting the e -success of recent conveyor miningsystems forLt. extraction. 1 GL C ,_tfreedom shoot &apos;_)`u 2--ethe.1 is coal while e en othershot firers re:7 t _e&apos; _U-tin , w J, e coal .Z- 311.ing States conveyors because ;-.;lax .ca requires thatblasting be limited to when c .. men os. _o tend neces¬sary officials 1 s . re out c-z ,r 7t ...y e:e l z<: woes no t a -¬#to 1 C" such restriction on blasting conveyor miningbeen extendedWhere ere t ere. re no _ c: t&apos;_ _c tit-----! . kind cutlasting;,1CL?; C&apos;. _ z)carried anI-7LC. AT continuouslyHowever, unless et._&apos;0:, precations are taken under r&apos;t e , accidents, n is or such, as111 electricity r 1C- from.J--_,._.1t ,° =&apos;1?without usingholes, as well as numerous-o _&apos;1&apos;-1 -= e troublehe record of mineexplosions (some of themSo so _C&apos;_ °:&apos;,v 0f rock- dusting]

Jan 1, 1941

By Pedro Máximo Ángeles

El presente texto señala el proceso «Strategic-Udy Modificado Angeles» utilizado para la producción de fierro o semiacero en Chimbote, Ancash. En ese sentido, durante la producción de aceros, es opcional el uso de fierros secundarios en la fundición (Scrap). La gran flexibilidad que ofrece el proceso permite producir tan bajo tonelaje sin sacrificar el costo de producción por tonelada de metal. Asimismo, las reparaciones pueden hacerse con gran facilidad, quitando la alimentación, drenando el horno eléctrico y cortando la corriente. Se puede operar el tonelaje deseado en una planta ya instalada con un pequeño descenso en la eficiencia. Por ello, es el método más adecuado en los lugares donde no se dispone de coke, tal es el caso de Chimbote - Perú y en donde se dispone de energía eléctrica barata, y de carbones que requieren procesos caros para su coquificación.

Nov 1, 1963

By R D. Lama, A Misra

One of the major factors restricting an increase in the productivity of a longwall mine is lower productivity obtained in a development panel. There has been a significant improvement in gate road development, particularly in mines requiring high density roof and rib bolting within 2 m of the face. Advance rates have increased from an average of 3 m to 5 m per shift in 1985 up to an average of 5 m to 10 m per shift in 1991. In mines at shallow depths with reasonably good conditions the increase has not been that significant. Advance rates have increased from an average of 7 m to 12 ni per shift in 1985 to an average of 12 m to 15 m per shift in 1991. Compared to the United States' (US) development rates, these are much lower. Extensive research work has been carried out to minimise cutting, wheeling, support setting time, and to optimise pillar length to achieve maximum advance rates. Pillar optimisation is very important in order to expedite adverse rates. This paper investigates various development rate technologies, both present and future, and optimises pillars to improve these dev elupment rates. Pillar optimisation is based upon time and motion studies conducted at mines in the Illawara region of New' South Wales, Australia, and the basic tools of arithmetic.

Jan 9, 1996

By I. Sedat Buyuksagis, Jamal Rostami, Ali Naeimipour

"Improving the safety of underground openings and optimizing ground support systems requires reliable ground characterization. This includes understanding the joints, discontinuities, and rock strength. Joint information can be obtained from borehole cameras, but measuring in-situ rock strength is very difficult. Use of borehole probes can be an ideal and efficient way to meet this requirement. This paper discusses the development of the Rock Strength Borehole Probe (RSBP) and presents the preliminary laboratory/field test. This device can be an accurate, flexible, quick, non-disruptive, and cost-effective alternative to estimate the rock strength inside boreholes in underground mines and tunnels. In addition, the scratch testing procedure in the laboratory by means of a newly developed miniature linear cutting machine is explained. Based on the results of these tests, two equations are developed to estimate the uniaxial compressive strength (UCS) and Brazilian tensile strength (BTS) of the sedimentary/metamorphic rocks. These equations, are based on testing 27 different sedimentary, igneous, and metamorphic rocks by full-scale scratch tests, including the cutting tests by a miniature disc. The results show a good correlation between the normal force and the compressive strength of sedimentary rock if the depth of the scratch is known. No significant correlation was observed for igneous rocks, due to the impacts of grain size.INTRODUCTIONEstimated rock mass properties are essential input for geomechanical studies and stability analysis for any structure constructed in or with rock. The availability of geological information is the crucial component of rock mass classification. One of the important parameters in evaluating rock mass properties is the intact rock strength. This parameter is usually measured by testing the core samples, obtained from exploration boreholes. These samples are subsequently tested in geomechanics laboratories. The test results offer limited information about the rock at the few boring locations despite all the efforts and costs. In addition, these results may not necessarily be representative of the behavior of the rock in the field as the test cannot provide the insitu condition of the ground."

Jan 1, 2016

By Wm. F. Netzeband

The purpose of this paper is to present to the operators, in other districts a detailed description of the ruining method used and the results obtained to exploiting one of the zinc-lead deposits of the Kansas-Oklahoma-Missouri district. No. 1. mine is located in the heart of the town of Picher in the extreme northeast corner of Oklahoma. HISTORY The first prospect drilling was done at No. 1 mine late in-1914, and shaft sinking was started early in 1915. Sufficient ore was developed to start construction of the mill in April, 1016, Production begin in August, 1916, and the mine s been producing, except for short periods, to the present time. The property was originally a 40-acre tract, but additional properties have been consolidated with the original one until the mine now covers 200 acres.

Jan 1, 1929

By Rolando Campos

In August 1993, the operation of Refimet Chile&apos;s copper custom smelter commenced at La Negra, near Antofagasta in northern Chile. Design smelter throughput corresponded to 235 000 tonnes of concentrate, calcines and copper cements arising from suppliers in the north of the country to produce 90 000 t/y of blister copper. Refimet had initially gained experienced in building and operating leaching, roasting and a blast furnace facility at Rungue, near Santiago, followed by Roasting at La Negra. The initial smelter project was based on conventional reverb- smelting and Peirce-Smith converting and the majority of equipment was &apos;purchased second-hand and rehabilitated or modified. After only 3 years in production, the treatment capacity was significantly improved by introduction of technical improvements to the original plant operating scheme. Recently, the plant was further expanded to an annual smelting capacity in excess of 400 000 t/y feed, corresponding to around 160 000 t/y copper production. This expansion, referred to as Phase 2, was achieved by modification of the reverb to oxy-fuel firing, addition of a further (second-hand) acid plant, fire refining and anode casting facilities. Parallel development of concentrate injection into enlarged converters-also took place. Following successful commissioning of Phase 2 expansion, initial engineering studies for a third expansion phase have been completed. This aims to use leading technology based on bath smelting of bone-dry concentrates in a Continuous Reactor. This paper provides an overview of the relatively short plant history, its development and improvements together with operating indices achieved.

Jan 1, 1998

By Thomas M. Barczak

The effect of load rate on the load-carrying capabilities of wood cribs is investigated in this Bureau of Mines study. The modulus of deformation (stiffness) of wood crib blocks has been shown to increase with increases in rates of load application, causing larger load reactions for increases in convergence rates. Since wood cribs are tested in the laboratory at convergence rates that are orders of magnitude faster than typically would occur underground, wood cribs tested in the laboratory will react larger loads than the same cribs would react underground for the same displacement. Tests conducted in the Bureau&apos;s mine roof simulator on green wood crib blocks indicate that the increase in stiffness for increasing load rates diminishes at displacement rates beyond 0.1 in/min, making crib load nearly independent of load rate for rates faster than 0.1 in/min. Seasoned wood specimens were not as con-sistent in load-rate dependency. Some possible explanations of observed load-rate behavior on wood crib specimens are also postulated in this paper.

Jan 1, 1988

By W. Mostowitsh

I. Introductory LEAD sulphate occurs as anglesite, and is formed in every roasting of lead sulphides or sulpho-salts containing lead. In smelting in the blast furnace an ore containing natural or artificial lead sulphate, a large part of the sulphur present goes to the formation of the intermediary product matte which requires further treatment for the recovery of the values it contains. It is therefore of importance to study the behavior of lead sulphate at elevated temperatures, both without and with reducing agents, especially as the information available gives data which are more or less conflicting. II. Decomposition of Lead Sulphate by Heat The dissociation of PbSO4 into PbO and S03 or S02 and 0 has been discussed by many metallurgists. The following data are considered to be representative. Doeltz and Graumann1 found that PbSO4 was not affected by heat at 800° C.; that dissociation began at 900° C., and was rapid at 1,000° when the salt lost in 1 ½ hr. 14.3 per cent. of its weight, the dry salt containing 26.43 per cent. SO3. Hofman and Wanjukow2 summarize their work upon the dissociation of metallic sulphates with the statement that the decomposition of PbSO4 begins at 195° C., but progresses very slowly, with the formation of the basic salt 6PbO.5S03 at 705°; that this salt undergoes a transformation at 847°, begins to be decomposed at 888°, to sinter at 896°, and to fuse at 910°; rapid dissociation begins at 952°, and is accompanied by volatilization of PbO; retardations at 958° and 962° indicate an acceleration of decomposition which, however, is not complete. Proske3 found that PbSO4 gave off at 900° C. in 30 min. only 0.63 per cent. of its SO3, and that the loss increased with

Jan 5, 1916

By Leahey T. A

The variability of gold mineralization in the Warrego Gold Pod is described by classical statistical techniques using sample distrib- utions and analysis of variance; and by the use of geostatistical variogram analysis to define the spatial variability and anisotropy of the mineralization. Comparison is made between declared mine production from the Nineteen Stope and a series of ore reserve estimates derived by manual, numerical and disjunctive kriging methods.

Jan 1, 1979

By Albert W. Cox

This paper, one of a series prepared for the United States Bureau of Mines discussing the methods used in mining, crushing, and grinding materials for cement manufacture, deals particularly with the methods used at the Security plant of the North American Cement Corporation. These papers are designed to disseminate technical information regarding the methods used. The cost tabulations represent local operating expenditures only and not total production costs. It is recognized that publication of, total production costs might in many instances cause embarrassment to individual producers as well as to the industry as a whole. On the other hand, operating costs are essential to the technical discussion and study of methods employed. The attention of the reader is specifically called to this differentiation in order that no misunderstanding of the scone of the cost tabulations shall ensue.

Jan 1, 1932

This publication summarizes, for potential contractors and all other interested parties, the research and development of in-house and contract projects programmed by the Bureau of Mines for fiscal year 1983 (October 1, 1982-September 30, 1983) under its Health and Safety Technology program. The objective of these projects is to provide an ordered and sequenced series of advance toward the Bureau&apos;s overall goal of providing the systems technology required to create a more healthful and safer working environment for the Nation&apos;s mining and minerals processing workers.

Jan 1, 1982

By Syd S. Peng

According to accident statistics (l, 2), roof fall accidents occur quite frequently at the intersections of underground? openings and account for up to 30% of the roof fall fatalities. But this figure will certainly go up considerably if roof falls not associated with any fatal accident are included in the analysis. Unfortunately, nonfatal roof falls are seldom documented. In the underground coal mines, there are two types of entry intersections. One is the three-way (V type) and the other is the four-way (T type) intersections. A three-way intersection occurs whenever the mainline track haulageway turns at an angle into a section haulageway. The four-way intersections by far the most common type in the U.S. under-ground coal mines are formed by the intersections of two entries which are oriented perpendicular to each other or by the intersections of entries and crosscuts. However, crosscuts are frequently driven at an angle to the entry to facilitate machine movements. The four-way intersections formed by this method of crosscut development are angled. At the intersection of two underground openings, the diagonal roof span is wider than the width of each individual opening. This is one of the major reasons why roof falls occur more likely at the intersections than in the entry between pillars. Consequently, special intersection support plans are usually employed (Figs. 1 and 2) for intersections. The most popular practices are to decrease roof bolt spacing 1 ft. less than or to increase roof bolt length 1 to 2 ft. longer than those employed in the entry between pillars (3). The increase in bolt length or decrease in bolt spacing can be applied to all of the bolts in the intersection or employed only for the strategically located bolts depending on the individual mine practices. These rather generalized practices seems to be adequate for some areas but in many cases inadequate for others. Occasionally, the neighboring two lines of chain pillars are staggered such that the crosscuts in one row of chain pillars face the centers of the chain pillars in the neigh-boring rows. This layout forms T-type three-way intersections which are also inadequate for most weak roofs (3, 4). A study was therefore initiated to develop special techniques for intersection supports. The first phase of the study was the analysis of the stress fields for the underground entry intersections. A three-dimensional stress analysis was necessary for this purpose. Unfortunately, the three-dimensional problems of complicated boundary conditions are beyond the existing analytical methods. The three-dimensional finite element method (FEM) was therefore employed in this study. In the analysis, square pillars of 40 feet wide and an entry height of 8 feet were assumed while entry widths varied at 14, 20 and 26 feet. This model was selected to simulate the mine where roof falls data were collected. The second phase of the study was the collection of field data. The sizes of the roof falls including heights, lengths and widths were collected and analyzed. In the third phase study, the results of the first and second phases were compared and discussed. The analysis of field data revealed an arching zone within which roof falls occurred. The arching zone above an entry obtained empirically was compared with the calculated stress contours. Assuming that the bolts must be anchored in the rock strata outside the arching zone, the preferable systems of bolting were proposed. Also the amount of pretension required to inhibit sliding between layers was discussed.

Jan 1, 1978

By C. A. Frenzel

Extensive spectroscopic data are needed in making reliable vibrational assignments for use in calculating thermodynamic functions of polyatomic molecules. The fundamental vibrations of organic molecules may be observed at any wavelength from 2.5 to 200 microns (micron = µ = 10-4 centimeters), but most often in the region from 3µ to 50µ. Raman spectra generally cover the range in which fundamental vibrations occur, but equally important infrared spectra usually are not measured at wavelengths longer than 25µ. This limitation results because most infrared spectra are determined for analytical purposes, which seldom require information outside the region 2µ to 25µ. Measurements of infrared spectra in the range 15µ to 35µ recently were begun by the Bureau of Mines to obtain data needed in making vibrational assignments. This report presents the spectra of the following thirteen compounds: Tetrahydrofuran, 1-methylpyrrole, piperidine, 2-methylpyridine, 3-miuthylpyridine, 2-propanethiol, cyclopentanethiol, 2-methyl-2-butanethiol, 3,3-dimethyl-2-thiabutane, cyclohexanethiol, cyclopentyl-l-thiaethane, 2,4-dimethyl-3-thiapentane, and hexamethyldisiloxane.

Jan 1, 1960

L. D. GODSHALL, Everett, Washington: This very interesting paper cannot fail to command the attention of every one who has ever had experience in the amalgamation of gold-ores. I wish to call attention to three very important facts brought out very prominently by the paper, namely: 1. The extent of accumulation of amalgam on copper plates in the form of scale, not removable in the ordinary manner; 2. The change in the relative quantity of the two metals in the amalgam as we. recede from the battery-discharge; 3. The difference in fineness of the bullion obtained from the above-mentioned scale as compared with the bullion from the daily clean-ups. From Mr. Bayliss&apos;s figures we find that during the life of the plate in question 14,942 tons of ore were crushed, yielding amalgam of the value of $5.03 per ton, or a total value of $75,158.26. The amalgam accumulating on the plate during this time as scale, we find to have had a value of $8340.54, or $0.558 per ton of ore treated, representing 11.09 per cent. of the total amount of amalgam saved in the ordinary clean-up; or, taking the amalgam saved by daily clean-up plus the amalgam-scale as representing the total saved on this plate, or 100 per cent., we find that the daily clean-up saved 90.01 per cent., while the scale represented 9.99 per cent. The above figures do not include some additional amalgam still adhering to the plate after scale had been removed. We are told that this was not an exceptional case at the Drum Lummon, but that other plates have even yielded a third more than the one in question. The interesting query now comes up, whether this experience at the Drum Lummon is exceptional or universal at all mills; and another question arises, as to how long such an accumulation might continue,

Jan 1, 1897

By Roger Bell

Most modern mines can profit from improvements in information handling. Recording systems in many cases were designed to satisfy certain necessary legal requirements, but not specifically to provide management information. As a consequence, the top managements of these properties work with cost data and production information that is dated, lacking in detail and clouded with supposition. It is the intent of this paper to describe an information system for a mine-plant complex in terms of the type of data, application areas and the existing equipment technology that may be applied to improve this situation. The economics of information processing and data handling will not be discussed in detail. This paper is based on the premise that information is something of value and that information processing like a manufacturing operation works for and is subject to management control. Information, the product, must be of quality, and the cost must be favorable in terms of its use.

Jan 1, 1965

By N. Nemeth

The filter is an apparatus designed to hold the filter medium. At such a medium takes place the entire liquid-solid or gas-solid separation process. Hence, the medium is really the essence of filtration. Yet, the medium, an originally clean porous substance with trapped solids in it, is perhaps the most neglected part of filtration research. Basically three problems prevail at the medium: 1) Penetration of solids and their blinding of the medium and the influence of such blinding on the resistance to flow. ii) The behavior of the medium in long term repetitive filtration. iii) The filter effect phenomenon whereby the flow rate on filtering an apparently clear liquid through a medium decreases with time. This study undertakes to investigate these fundamental processes.

Jan 1, 1968

By William Campbell

FiRst I must express my deep appreciation for the honor of being privileged to give the Howe Memorial Lecture this year and at the same time my feeling of inadequacy to do justice to the subject. The first Howe lecturer was most fittingly, Professor Sauveur, his contemporary and friend, and the subject was beta iron. Last year the second Howe lecture was delivered by Dr. Mathews, one of his most distinguished pupils, who spoke on austenite. This year, the Howe Professor of Metallurgy was chosen to deliver the third annual lecture, and the subject ought to be martensite. No one but Professor Sauveur could have brought to life what was considered by many to have been dead and buried, and he so persuasively and convincingly proved to us by his experiments the existence of something that the followers of that new cult "X-Ray and Crystal Structure " would have us believe is simply alpha iron. And Dr. Mathews from his wide practical experience was so easily able to convince us that austenite was not only the most wonderful of the iron-carbon series, but that it was the wonder alloy of the future. If I were to follow in the footsteps of my distinguished predecessors, I would talk to you about martensite. But when I had planned this lecture, I found that I was writing about Professor Howe and his work and his influence on the science of metals of today, and that martensite had become the secondary theme. And when finally I was obliged to choose a title, I remembered that it was in 1901 I came from Roberts-Austen with a letter of introduction to his very dear friend, Henry Marion Howe, at the Columbia School of Mines, to continue my work at the next bench to Dr. Mathews. Since then a quarter of a century has gone by, and during that time all branches of science seem to have been remade, so great has been our advancement in knowledge and discovery. And now that Metallography has finally established its place as an important branch of science, with its own textbooks and literature, I would like to review what seem to me to be the most important advances we have made in the last 25 years. To do this, I would start with Howe&apos;s "Iron, Steel and Other Alloys," and end with Jeffries and Archer&apos;s " Science of Metals." In the preface of the former, Professor Howe wrote: My warmest thanks are due to the friends who have aided me with their counsel and knowledge. In particular, let me thank most sincerely Prof. Margaret E. Maltby

Jan 1, 1926