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By H. C. Ko

Heats of solution of calcium carbon-ate (calcite) and calcium oxide in hydrochloric acid were determined by solution calorimetry. Combination of these two heats yields a value of 42.643±0.024 kcal/mole for the enthalpy of calcination of calcite at 298.15 K. Literature data on ?H°298.15 of calcination of calcite were reviewed and compared. Thermodynamic properties for the calcination process were calculated from 298.15 to 1,500 K using Gibbs energy functions. This research was undertaken by the Bureau of Mines as an effort to provide thermodynamic data for the advancement of minerals technology, energy conservation, and environmental preservation.

Jan 1, 1982

By E. Wainer, K. D. Burnham

A wet beneficiation technique for producing wollas-tonite from its ore in high yield and purity has been evaluated in a pilot plant operation at the rate of 75 tons per month. Finely crushed, unsized wollastonite ore mixed with water is passed through a high in tensity oscillating wet magnetic separator of unique design and in a single pass over 90% of the wolla-stonite exhibiting a crystal purity of 99.8% is obtained irrespective of size of feed fraction. Thereafter, the material is processed by closed cycle standard wet milling and classification techniques to yield a 1µ size product, though any mesh size up to and including 50 mesh may be obtained, if desired. Costs appear to be significantly lower than those available from dry processed techniques. Wollas tonite made by this unusual wet process appears to have potential utility in the following fields: ceramics, paints, plastics, paper, organic finishes, reinforcement of portland cement items, controlled porosity refractory ceramic foams, cinder and concrete block paint, and the like. The 1µ and certain chemically processed varieties of wollastonite may have unusual utility in the paper industry both as a filler and as a coating material and in the organic finish industry. Extensive deposits of wollastonite ore equivalent to an average tenor of 50% to 60% of this latter mineral in easily separable form exists in and around Essex County in northern New York State in reserves of the order of several tens of millions of tons. While important portions of these deposits are susceptible to open pit mining techniques, one operation near Wills-boro, N.Y., involves tunnel mining and dry milling and beneficiation techniques. This mill and tunnel mine is presently being operated by The Cabot Corp. and a variety of particle sizes are now sold into markets in the ceramic, paint, plastic finish, floor tile and in similar fields in substantial tonnages on a repetitive basis. Serious investigation and study over the past several years has indicated that, outside of the obvious economies of open pit techniques for mining purposes, wet beneficiation and milling procedures applied to the ore not only represent a potential for greater economies in the production of a superfine finished product but yields products of improved properties exhibiting increased market potential which may not be available from the dry ground product. The Lewis and Deerhead deposits, controlled by the Adirondack Development Corp., appear to be identical to the Wilisboro deposit. Utilizing ore taken from the Lewis and Deerhead deposits, a pilot plant process for the wet beneficiation, milling and classifying of wollastonite ore has been operated for several months. After scalping a marketable garnet product from a minus 16 mesh dry crushed feed on a high intensity roll magnet the balance of the material is then roll crushed in a closed cycle until it will pass a 50 mesh screen. The product constitutes the feed of the wet magnetic separator. The heart of the new beneficiation process is a cyclically operated wet magnetic separator which exhibits the unique feature that unsized feed is easily handled. Product yields of higher purity are equal to that obtained with dry magnetic separations which use closely sized dry ore and multiple passes, but only produce wollastonite of about 98% mineral purity as determined by sink float techniques. It was anticipated that the wet processing through the grinding, milling and classification stage would yield a low cost 1µ ground product which should make available greatly increased applications for the mineral beyond those presently enjoyed. The improved purity was also expected to provide coarser sizes which might be utilized as a raw material for chemical modification which again would expand the uses of wollastonite. The evidence thus far collected appears to indicate that this premise may be expected to be fulfilled. There are on the surface of wollastonite particle sites at which cheinical reactions may occur1. It is believed that wet ground material provides a better base which will allow wollastonite a deeper entree into the field of chemical raw materials. Wet ground at 20µ and finer permits with certainty a number of chemical reactions, some of which are mentioned later in this article. While well crystallized wollastonite makes up the majority of the ore, the balance consists mainly of very weakly magnetic diopside of the hedenbergite-

Jan 1, 1965

By Kyle Selga, Christopher J. Greet

"The Pulp Chemistry Monitor (PCM) has been installed and operated in a number of concentrators in Australasia, and has produced some very interesting results. PCM measures the pH, Eh, dissolved oxygen, temperature and oxygen demand of process streams within a concentrator continuously and in real time.In the example presented in the paper the cleaner feed pulp chemistry is measured, and related back to changes in the mineralogy as well as variations in metallurgical response. For example, a decrease in Eh and dissolved oxygen as well as an increase in the oxygen demand. These changes in the pulp chemistry appear to coincide with increases in the feed grades, probably higher pyrite grades. Further, these variations in pulp chemistry and feed mineralogy have a negative impact on the concentrate grade and recovery.The implication is that if the pulp chemistry is monitored it is possible to predict changes in the mineralogy of the system, and from this the metallurgical response. Further, the changes in pulp chemistry can be used in a control system to counter the changes in mineralogy and maintain the metallurgy.IntroductionIt has long been recognized at a fundamental level that the flotation behaviour of sulphide minerals is dependent on the pH and Eh of the system (for example: Tolun and Kitchener, 1964; Woods, 1976). However, measuring pulp chemical parameters within an operating concentrator has had limited attention. Woodcock and Jones (1970a and b) were among the first to actually collect data from operating plants. Jones and Woodcock (1984) identified some of the chemical complexities of flotation pulps, and noted that most concentrators already operate at high levels of metallurgical performance but there was still considerable scope for improvement. These gains would, in part come from more effective chemical control. In the same volume, Healy (1984) discussed metal ion hydrolysis and precipitation, redox chemistry and how the surface chemistry of sulphide minerals can be influence flotation behaviour. The impact of grinding environment on the pulp chemistry and flotation response of a complex polymetallic sulphide ore is discussed by Forssberg and Subrahmanyam (1993). Their work essentially contrasts the pulp chemical and flotation performance of pulps ground with conventional ferrous grinding media to a fully autogenous system. The data suggested that the reduction or removal of iron hydrolysis contamination from the system could have a positive influence on flotation behaviour, and perhaps the first stage of “controlling” the chemistry of the system should be in the grinding circuit. Grano et al (1995) demonstrated that the collection of pulp, solution and surface chemical data could identify weaknesses within a concentrator, and from these data develop, test and implement solutions that improved the process. Greet et al (2006) showed that the pulp chemical trends observed through primary grinding and rougher flotation circuits of most sulphide flotation concentrators are approximately the same. There are differences in the magnitude of various pulp chemical parameters (pH, Eh, dissolved oxygen, temperature and oxygen demand) as a result of variations in the feed mineralogy and processes employed. Further, it was noted the Eh shifted to more reducing values of the ten days measurements were collected, and this change could be traced to an increase in the iron sulphide content of the feed. Metallurgically, this resulted in an increase in nickel recovery through the recovery of nickeliferous iron sulphides, and a decrease in nickel concentrate grade."

Jan 1, 2016

By Jiwei Duan

The deformation and load transfer behavior of a single soil-cement column are studied with the finite element method. The results show that there is an effective length for a soil-cement column. Beyond this length, the settlement of the column is approximately equal to a constant. The effective pile length is introduced to the concentric cylinder approach (Randolph and Wroth 1978), and an analytical formula for estimating the settlement of a single flexible pile is presented. A second analytical formula for determining the effective pile length of a soil-cement column is obtained and an example shows that the calculated and measured results are in quite good agreement.

Jan 1, 2002

By H. C. Gunning

SOME small vanadium-bearing deposits on the west coast of British Columbia about 100 miles north of Vancouver are of interest for several reasons. They are of a type that is, so far as we know, unique. They are difficult to identify as being vanadiferous so that, unless they are described, other similar deposits could easily pass unrecognized. Furthermore, although none of them has as yet been proven to be of commercial proportions, no good reason is apparent why larger, and therefore valuable, deposits should not occur under similar geological conditions. The original discovery on Quadra island was made in 1932 and has been recorded by H. V. Ellsworth and H. C. Gunning (l). Since 1932, prospecting in the area has revealed other similar deposits, one about a mile south of the original and another some ten miles to the east, near Menzies bay on Vancouver island. The Quadra Island showings are a mile and a half north of the head of Gowland harbour, a small inlet that is easily reached by gas boat from Campbell river, about four miles to the southeast on Vancouver island. The deposits were examined by the writers in the spring of 1943 in connection with field work sponsored by the Department of Geology, University of British Columbia. We are indebted to Mr. G. A. Dirom and Mr. Lothrop, of Vancouver, for helpful data on the Menzies Bay deposits, and to Dr. V. Dolmage for making a brief trip to Gowland harbour and discussing the deposits.

Jan 1, 1944

By N. A. Zeigler

GRaphitization phenomena occurring in solid cast iron have principally been studied from the angle of the reactions taking place during annealing of white castings in the manufacturing of malleable iron. The selected bibliography at the end of this paper presents the high spots of the published information in this field. Graph-itization of gray iron upon reheating has received much less attention, primarily because only on rare occasions is this material subjected to any kind of industrial heat-treating. Moreovcr, articles made from gray iron are seldom used commercially at temperatures when any graphitization can take place. When used in such conditions, it is assumed that the articles can be replaced at frequent intervals, which can be afforded because of the low cost of gray iron. However, there is at least one commercial process in which articles made from gray iron, during their manufacturing processing, are subjectcd to rather high temperatures; that is, manufacturing of cast-iron enamelware, which is glazed at about 1600° to 1700°F. (870' to 930°C.) From practical experience, it has been found that one of the convenient and economical compositions of gray iron suitable for enameling is, in round figures, as follows: Si, 2.50 per cent; Mn, 0.35; S, 0.07; P, 0.80; T.C., 3.35; C.C., 0.70. Since this iron usually is cast into thin-walled sections, the percentage of com- bined carbon in it is relatively high. Upon heating in the enameling furnaces, this combined carbon graphitizes, which causes permanent dimensional changes of the articles. Obviously, from practical considerations, it is desirable to maintain these dimensional changes as constant as possible. In the course of experimentation with this iron, two series of experimental heats were prepared in which the manganese to sulphur ratio of the standard cupola metal was offset by ladle additions of: (I) progressively larger amounts of sulphur, and (2) progressively larger amounts of manganese. Each one of these ladle charges was cast into experimental plates 8 by 4 in. and about 5/16 in. thick. All told, 13 ladle charges were thus treated. All of them are listed in Table I, together with their chemical analyses. It may be noted that the manganese to sulphur ratio in these samples ranges between 1.2 and 30.2. Every one of these compositions was subjected to thermal allalysis, using an automatic, self-recording differential dila-tometer. The specimens used in this instrument are 50 mm. long and 4 mm. in diameter. During the dilatometer cycle they are kept under a vacuum of about 3 microns. Each one of them was subjected to a thermal cycle by heating it to I830°F. (1000°C.) in 3 hr. and cooling to room temperaturc in 5 hr. Figs. I, 2 and 3 present three automatically recorded dilatometer curves for irons: Serial No. I (normal composition), Serial No. 6 (high sulphur), and Serial No. 13 (high manganese). All three of these figures are

Jan 1, 1945

By H. P. Greenwald, G. E. McElrey

"Part IV.- The Resistance Caused by Right-Angle Bends. IntroductionThis paper deals with the fourth phase of an extensive research on coal-mine ventilation factors. A comprehensive report of the entire work is in course of preparation, but abstracts of the various chapters are being prepared in order to make the major results public as rapidly as possible. Parts I, II and III were issued as Serials Nos. 2621 (July 1924), 2647 (October 1904) and 2671 (March 1925) and dealt with the resistance of unobstructed entries, the resistance due to mine cars and, the resistance of timbered entries respectively.Description of the Tests With the last cutthrough between the two butt entries of the test section in the Experimental Mine open, the air flow was deflected, around two right-angle bends in the same direction, the butt entries being 50 feet center to center and approximately 6 by 9 feet in cross section. Each bend had a dead end opening off of it; that at the first bend was in the direction of flow and that at the second bond was at right angles to the flow. For a primary test condition the inner corner of each bend was trimmed square and the dead ends were closed off with board brattices set flush with the line of the cut-through.The two corners of the first band were, then modified both independently and in conjunction. Various modifications of both bends in conjunction were also tested with rather surprising results as to the effect of conditions at the first bend, upon the pressure losses at the second. To confirm the theory developed to fit these results a series of tests were made to give a direct comparison of the -pressure losses as between two bends with the air flow deflected in the some direction at each and with the air flow deflected in opposite directions. The former is designated ""double"" and the latter a ""reversed"" right-angle bend. This series of tests was conducted, however, on the bends at one of the intermediate cutthroughs at which the flow could be deflected us either direction at the second, bend. Here also the average cross-section was 6 by 9 feet and the bends were 50 feet apart."

Jan 1, 1928

By Leiting Yue, Peng Ren, Yu Shen, Zhihong Liu, Haibao Shao, Longgong Xia, Feng Yu

The Kennecott-Outotec Flash Converting technology has been proven as an advanced and mature process in 5 individual plants during the past 2 decades. High grade copper matte (65–72%) produced in the flash smelting, or other smelting technologies is granulated to 3-5mm granules in a water torrent, and further crushed to fine powder (≈50µm) and dried to contain less than 0.3% H2O. Oxygen enriched air, together with fine copper matte powder and lime flux are injected into the reaction shaft by a matte burner. The copper making and slag making reactions will happen in very short time and distance during the particle falling and settling. However, industrial practice has found negative effects caused by sodium contamination. Na is introduced in the copper matte granulating process, and appears as Na2SO4 on particle surface. When Na content was high, scaling problems in the boiler will be worse, and the processing air will be blocked by the growing accretion around the matte burner, and as-produced blister copper is always high in S and O. In this present study, an industrial matte sample was used in the experimental work. Na was introduced into the matte powder by Na2SO4 solution soaking. The burning behaviour of the doped copper matte powder has been investigated as a function of the impurity concentration and processing temperature. Morphology and composition of these samples explained how Na2SO4 converts and reacts in the oxidizing atmosphere, and how they or their converting species influence the burning behaviour of matte particles. Cross-sections of as-prepared samples were analyzed with SEM-EDS, and the reaction mechanism has been carefully interpreted. Results from the present study can benefit both academic and industrial people. INTRODUCTION "Flash Converting" technology was developed jointly by Kennecott Utah Copper Smelter and Outotec (Finland) OY in 1992. The first industrialization of the technology was in Utah Smelter in 1995. Since 2006, it has been successfully applied in Xiangguang Copper, Tongling Jinguan Copper Branch, Fangchengang Jinchuan Copper, and Ningde Southeast Copper. The technology has also been further developed in those smelters. At present, roughly 2 million tons blister copper is produced annually through the Kennecott-Outotec Flash Converting technology, accounting for more than 10% of global primary copper production. The technology has advantages of high efficiency, high sulfur capture rate, good in environmental issues, mature equipment supporting, high automatic control level, low comprehensive energy consumption and flexible connection with the smelting unit, which make the technology to be one of the best choices in investing a new large-scale copper smelter or updating an old copper project in the world.

Jan 1, 2019

By R. A. Garling

INTRODUCTION Since the infancy of in situ uranium mining, a growing number of hydrometallurgical processes have been incorporated into pilot and commercial scale flowsheets. Although initial design efforts were geared toward maximizing uranium recovery and minimizing plant and wellfield flow circuit maintenance, recent emphasis has shifted to improved means of water conservation and aquifer restoration. As mining units approached depletion, evaporation ponds reached minimum freeboard, and state and federal agencies demanded proof of groundwater restoration, processes including mixed bed and conventional ion exchange, reverse osmosis and electrodialysis were adopted by the industry. These units served the additional function of reducing process bleed flows during mining in states where the deep disposal well permitting ice remains unbroken. This report concerns the use of electrodialysis as an alternative to the more conventional processes used in in situ mining. In addition to a brief history and description of the process, a comparison to reverse osmosis and operational data derived from testing an Ionics, Inc. 1.31 x 10-3 m /s (30,000 gallon/day) unit at the Teton-Nedco Leuenberger Research and Development pilot will be presented. HISTORY Commercially practicable electrodialysis was contingent upon the development of synthetic ion exchange membranes in 1940's. In 1952, Ionics Inc. demonstrated that the process was amenable to the treatment of salt and brackish water and, in 1954, made their first commercial sale. The following decade saw several major electrodialysis unit sales which were generally targeted for use on private or municipal potable water treatment. Major increases in membrane desalting unit capacities, facilitated by technological advances in the reserve osmosis industry, were noted during the 1970's. The development of polarity reversing electrodialysis equipment which reduced feed pretreatment requirements, increased water recovery rates, and simplified unit operation, kept Ionics Inc. competetive in the water treatment industry. Engineering advances which incorporated automated equipment, non-corrosive construction materials, and improved ion exchange membranes allowed the electrodialysis process to compete in industrial waste treatment among other commercial markets. PROCESS AND APPARATUS DESCRIPTION The electrodialysis process utilizes direct electrical current passed across a stack of alternating cation and anion selective membranes in order to achieve an electrochemical separation of ionized materials in an aqueous solution. The membrane stack has the appearance of a plate and frame filter press and auxilliary equipment includes solution pumps, electrically actuated valves, filters, piping and a direct current power source. The ion separation membranes are thin sheets of synthetic cation or anion selective resins. Attaching sulfonate or quaternary ammonium groups to the cross linked copolymer structure determines the ion selectivity of the membrane. The membranes are separated from each other in the stack by non-conductive spacers that house flow channels which route the flow tortuously and parallel to the membranes. Direct electrical current passing perpendicularly to the membranes and solution passages attracts cations toward the cathode and anions toward the anode (Figure 1). As the ions from the feed stream pass through the ion selective membranes, they become concentrated in the adjacent brine channel and are retained there by the combined attractive force of the electrode and the repelling force of the next membrane toward the electrode. Limiting factors on the degree of demineralization possible include chemical solubilities in the brine flow and the current density that will produce an unacceptable degree of polarization (Figure 1). Feed or brine solution treatment with complexing agents or acids has been successfully applied to prevent membrane scaling. Polarization can occur when sufficient current density is applied to dissociate water in the ion depleted region of the diluting compartments near the membrane surfaces. Significant polarization is evidenced by large electrical resistances across cell pairs and notable pH differences between diluting and concentrating streams. Limiting current densities have been increased in U.S. manufactured equipment by utilizing tortuous flow paths of relatively high linear velocities thereby promoting continous solution mixing. Energy consumption is due to separating electrolytes and solutions, oxidation and reduction reactions occurring in electrode compartments, overcoming electrical resistance, conversion from AC to DC power, solution pumping and auxiliary equipment actuation. A major improvement to the basic electrodialysis process was applied in 1970 which resulted in frequent, automatic cleaning and descaling of membrane surfaces. The process, polarity reversal, incorporates alternating the cathode and anode on a periodic basis while exchanging product and brine flow channels via electrically actuated values. The reversal reduces the potential of stack plugging with CaCO3 (calcite), CaSO4 (gypsum), and colloidal materials and, in most waters, eliminates feed pre-treatment requirements. For approximately two minutes during and following the reversal, off spec. water is flushed to waste or reintroduced to the feed supply. The usual feed treatment on polarity reversing electro-

Jan 1, 1982

By M. Misra

The dissolution of mercury during gold cyanidation is the cause of many environmental, health and processing problems. A study was undertaken to find a suitable reagent for the removal of mercury bearing complexes from the leach liquor. Removal of mercury from synthetic solutions and process water from a gold mine was investigated using sodium sulfide, sodium and potassium dimethyl dithiocarbamates as precipitating reagents. The results have shown that efficient mercury removal could be achieved by addition of potassium dimethyl dithiocarbamate (KDTC), by formation of stable mercury compounds. The resultant mercury-potassium dimethyl dithiocarbamate precipitates are stable under present plant operating conditions and do not have any deleterious effect on gold adsorption by activated carbon. Furthermore, it is also possible to stabilize the mercury in the heap during cyanidation by adding dimethyl dithiocarbomate.

Jan 1, 1998

By Frank E. Cash

Accident prevention is an integral part of the operating procedure of the petroleum industry, and refinery officials and employees throughout the United States are exerting concerted effort to reduce the frequency and severity of accidents and are realizing definite results. In other words, the petroleum industry is safety conscious to a much creator decree than most of the other mineral industries. On January l, 1936, there were 11 operating, refineries in Louisiana with a crude-oil capacity of 199,750 barrels per day.4/ This report deals with safety in four of these refineries representing. 72 percent of the refinery capacity of Louisiana.

Jan 1, 1940

By W. D. Forgeng, B. F. Decker

IT has been known for almost a century' that silicon and nitrogen combine when heated to a high temperature. Three nitrides have been reported, SiN, Si3N,, and Si,N, containing 33.3, 40.0 and 42.9 pct nitrogen by weight, respectively. The existence of SisN, is well established but that of Si,N, and SiN is doubtful. The first systematic study of the reaction between silicon and nitrogen was made in 1910 by Weiss and Engelhart" who determined the rate at which silicon absorbed nitrogen at temperatures from 1250°C to

Jan 1, 1959

By Fred N. Kissell, Jon C. Volkwein

In This Chapter [How inert gas works to prevent methane explosions How inert gas is generated and delivered at highwall mines Volume and quality requirements for inert gas at highwall mines How an inert gas system is operated and Precautions to take during mining to prevent methane explosions] This chapter discusses a method, originally developed by Volkwein and Ulery [1993], to prevent methane explosions during highwall mining. In highwall mining, a horizontal auger or a mining machine enters the coal seam from a surface mine pit at the bottom of a highwall, and the coal is mined out from a series of parallel holes. Explosions can be prevented by injecting inert gas into each hole as it is mined. Coal near the surface has lost most of its methane gas over time. However, in recent years, surface mining has been used for deeper reserves of coal. This trend toward mining deeper reserves has increased the chance of encountering methane, and methane explosions at highwall mining operations have resulted in injuries. HOW INERT GAS WORKS TO PREVENT METHANE EXPLOSIONS A methane explosion requires the presence of sufficient amounts of both methane and oxygen, as well as an ignition source. If the methane cannot be reduced and the ignition source cannot be eliminated, then explosions may be prevented by adding an inert gas, which contains little to no oxygen, to the mixture [FWQA 1970]. Just how much inert gas must be added depends on the mining rate, as well as the composition of the inert gas. An explosibility diagram can be used to show whether a methane mixture is explosive after inert gas is added [Zabetakis et al. 1959] (Figure 10–1). This diagram indicates that gas mixtures fall into one of three range categories—explosive, explosive when mixed with air, and nonexplosive—depending on the percentage of methane and percentage of “effective inert.” Effective inert is calculated from the percentage of “excess nitrogen”3 and percentage of carbon dioxide in the mixture.

Jan 6, 2006

By Y Li, S Ramazan, E Topal

A mine waste dump progression plan can provide a clear outlook of the mining operation. To produce such an output requires detailed placement schedule of the mined material, including the volume (or tonnage) and the allocated dumping location. However, current practise mainly focuses on the ore production, over-simplifying the waste material scheduling. As a result, a rock dump is often treated as a single point in long-term planning, making it difficult to predict the waste dump progression pattern over the life-of-mine. Without such a guidance, it is almost impossible to carry out progressive rehabilitation on the waste rock dumps. The lack of dumping schedule could cause delay in development construction, ie tailing storage facility and run-of-mine pad. Other downstream effect due to the over-simplification is inaccurate estimation of required truck hours, which could have huge financial impact on the operation.In this paper, mixed integer programming (MIP) models of different objective functions, ie maximise truck productivity by minimising the overall haulage distance, minimise required truck deviation between adjacent years, and a hybrid between the two objectives, are utilised to generate the long-term optimum rock placement schedules under the criteria of satisfying site specific conditions. All three MIP models are implemented in a large scale open pit mine. The numerical solutions from the models forms three different rock placement schedules, based on which, the yearly truck requirements are easily calculated and compared. The graphical results show the three corresponding waste dump progression patterns over the life-of-mine, providing the optimised long-term forecast of the operation.CITATION:Li, Y, Topal, E and Ramazan, S, 2014. Optimising the long-term mine waste dump progression and truck hour schedule in a large-scale open pit mine using mixed integer programming, in Proceedings Orebody Modelling and Strategic Mine Planning Symposium 2014 , pp 335–344 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 24, 2014

By W. S. Gatley, F. C. Appl

This paper presents a combined analytical and experimental study of chisel penetration vs time during chisel impact on rock, a problem of fundamental importance in improving the performance of roller-cone bits or percussion drilling toots. For a given force-time relationship between chisel and rock, the problem of determining the penetration (displacement) vs time of the chisel is formidable. This is so because the rock is a nonlinear system with distributed mass and distributed damping (friction, dissipation of energy due to rupture, etc.). Since the literature does not contain adaptable solutions, the rock behavior to impact was simulated approximately by an "equivalent" lumped system, that is, an "equivalent" mass, spring, dashpot system. With this assumption, an analytical solution was found for chisel penetration vs time due to a sinusoidal load between chisel and rock. From this solution were found curves, in terms of dimension-less variables, for the maximum depth of penetration vs the frequency of the sinusoidal loading and for the energy transfer vs frequency. The results of this analysis were used to predict the penetration rate of rotary rock bits us rotary speed. The curve indicated that an optimum speed exists. To verify this analysis, an experimental apparatus was constructed and used to apply a sinusoidal pulse to a chisel penetrating a rock specimen under atmospheric conditions. Strain gauges were mounted on the chisel shank and a velocity transducer was mounted between the chisel and the rock surface. The velocity was integrated electrically and picked up simultaneously with the strain gauge signal on an oscilloscope. Permanent records were made photographically to provide simultaneous records of force us time and penetration us time. In comparing the experimental results for limestone and dolomite with the theoretical results, good agreement was found in the frequency range of the experiments. Unfortunately, the inertia effect (peak penetration) indicated by the theory occurs at a frequency much higher than could be obtained experimentally with the apparatus constructed. A "rate-of-loading" effect is indicated theoretically, but has not yet been verified experimentally. INTRODUCTION The process of drilling with percussion tools or rotary rock bits is basically related to the transient response of rock to surface impact. Each time a bit tooth contacts the rock, high stresses are developed which result in penetration and rock removal. As the tooth moves on, stresses are relieved and a new cycle begins as the next tooth contacts the rock. Thus the drilling process, which consists of an endless succession of these cycles, can be studied in terms of a single cycle. It is apparent, therefore, that the study of single-chisel impact on rock is fundamentally important in improving the performance of roller-cone and percussive-type drills. Previous studies in this area have been conducted by Simon1 and Hartman2 by means of drop tests. In these tests a chisel was attached to a weight and allowed to fall, due to the force of gravity, so that the chisel was driven into a rock specimen upon impact. Strain gauges were attached to the chisel shank and the resulting force-vs-time curves were recorded photographically from an oscilloscope screen. The depth of penetration and crater dimensions were also measured. These tests have provided much valuable information but, as mentioned by the investigators, have not provided complete information on the effect of "rate of loading'! This is partly due to the fact that the chisel motion during drop tests is not a controlled motion which can be varied in form and frequency. Therefore, it seemed that additional information could be obtained by studying chisel impact under conditions where both the motion and the frequency of loading could be controlled. This paper presents a combined analytical and exper-

By D. F. Hewett

CONTENTS PAGE Introduction 1 Geologic features of eastern Oregon 2 Geology of the Sumpter quadrangle 2 Rocks older than the ore deposits 3 Rocks younger than the ore deposits 8 Lodes of the Sumpter quadrangle 8 Areal distribution 8 Geologic distribution 9 Major features of the veins 9 Mineralogy and texture of the veins 13 Ore deposits zonally disposed around the Bald Mountain batholith . . . . 13 Summary of mineralogy and texture 32 Zonal relations 33 Ore deposits zonally disposed around Greenhorn Mountain batholith . . . 36 Zonal relations 37 Relation of textural features to zonal arrangement of veins 37 Summary of zonal relations 38 Comparison with similar districts 39 Outlook for the district 40 INTRODUCTION IN an earlier report on the Sumpter quadrangle1 it was briefly stated that the quartz lodes of that region might be separated into several groups or belts on the basis of the kind and abundance of the minerals of which they are composed, and that these belts were disposed as areal zones around the principal intrusive mass of the region. When the opportunity to revisit the region was offered in 1929, as a result of a cooperative agreement between the State Mining Board of Oregon and the United States Geological Survey, it seemed advisable to pay particular attention to this feature of the lodes, in the hope that if the idea of zonal relations was confirmed it might serve as a guide in exploitation.

Jan 1, 1931

By E. Buehler, R. H. Willens

A Hew melting technique has hem adapted to the rapid quenching of- alloys from the liquid state. The inelting method has no limitations on the alloys investigated for there is no reaction with crucible materials and the most refractory materials are easily melted. The vate of heating is so rapid that alloys which have a high vapor pressure constituent can be melted with a minimal loss in material. Several new superconductovs have been discoveved by vapid quenching of lolten alloys. THE rapid quenching of alloys from the liquid state has led to the discovery of many new metastable phases. The methods initially used were limited to alloys which did not react with crucible materials.1,2 There was also the unmentioned limitation in tem- perature. Alloys with melting points much greater than 2000°C could not be melted in the rapid-quench apparatus. Recently, there have been successful attempts to rapidly quench reactive alloys by Moss et at. and Matthias Moss et al. injected powdered material (325 mesh) into a high-temperature plasma and the high-velocity molten droplets impinged on a cooled copper plate. The technique innovated by Matthias was to melt the alloy in an arc furnace and splatter it against a copper plate by means of a high-velocity gas jet aimed at the melt. I) FAST COOLING APPARATUS The creation of a metastable phase in a given alloy system by rapid cooling from the melt is contingent on the quenching rate. Some alloys require very slow rates while other alloys require the ultimate in quenching rate. At the present time, the vertical-gun technique of Duwez and willens' has demonstrated, in practice, the highest quenching rates and thus the best

Jan 1, 1967

By R. S. Saunders

Congress, under the Nuclear Waste Policy Act of 1982, as amended, charged the U.S. Department of Energy (DOE) with the responsibility for safe and permanent disposal of high-level radioactive waste in a geologic repository. The waste will consist of spent fuel from commercial nuclear generating plants and reprocessing activities. Under direction of this law DOE is currently evaluating Yucca Mountain in Southern Nevada as the candidate site for a potential high-level radioactive waste repository. Presidential, Congressional and State of Nevada approval are needed for repository construction to proceed after successful completion of site characterization and recommendation of the site to Congress. The DOE will submit a license application to the Nuclear Regulatory Commission (NRC) to construct the geologic repository. Following successful construction DOE will update its license application to operate the repository.

Jan 1, 1993

By R. G. Gifkins

Mean boundary migration depended linearly upon creep extension under various conditions. Prolonged annealing or air-casting increased the proportion of immobile boundaries at a given stage of tests. Grain growth during annealing followed a power law. The linking of migration and sliding in creep and models for migration are examined; activation energies are calculated from these models. Segregation of oxygen to boundaries appears to be a controlling factor. THE idea that boundary migration and boundary sliding during creep are linked has often been suggested,'-5 especially when evidence has been obtained for an alternation between the two processes. In simple bicrystals sliding can occur without any migration6 but in more complex bicrystals7 it is observed. McLean' and Couling and Roberts 5 made measurements of both sliding and migration; McLean concluded that there was no linking of the two processes whereas Couling and Roberts supported the idea. McLean' also developed a model for migration during creep and annealing. The present work was initiated as part of a study of the recrystallization of lead during creep9 but has been extended to examine some aspects of the mechanism of migration. MATERIALS AND METHODS Specially refined high-purity lead* was used; the total of impurities, excluding oxygen, was 0.0008 wt pct. Oxygen was removed as far as possible by melting in vacuo, treating at 550" to 600°C with hydrogen and then casting at 450°C under a vacuum of 10-2 mm Hg; the oxygen was then believed to be 0.00005 wt pct. Specimens were made from extruded strip and then annealed at the required temperature in an air oven, controlled to 5 lac. They were then polished in a mixture of acetic acid and hydrogen peroxide. At this stage some specimens were etched to give grain contrast and their grain sizes determined by the intercept method. Migration of boundaries during creep was measured on the surface of polished (not etched) specimens, directly loaded at room temperature (22°C) or 50°C (52"C) to initial stresses of 300 to 700 1b per sq in. Twenty six vacuum-cast hydrogen-reduced specimens were used and, in addition, two specimens were from material air cast after hydrogen reduction ("partial" air cast) and two from air-cast material not treated with hydrogen ("full" air cast). Duplicates were made in the majority of tests. At intervals through the creep tests, specimens were unloaded and the migration measured, normal to the direction of migration at the point of measurement, for each boundary along standard traverses. Usually between 110 to 180 boundaries were measured at each of some twelve stages of the tests. Migration was measured on the projected image (X100) using prism illumination. Fig. 1 illustrates the method of measurement and shows the kind of variation of migration found from boundary to boundary and along particular boundaries. Fig. 2 gives an example of more extensive migration. The mean value of distance migrated was generally reproducible to *10 pct but occasional points gave a scatter of *20 pct. The correctibn applied by McLean8 to allow for the contribution sliding makes to the apparent distance of migration could not be used, for the sliding at most boundaries was too small to measure with the equipment available. There were two reasons for supposing the correction unnecessary in the present work;

Jan 1, 1960

Underground mining alters ground condition, producing a disturbance in the ground water regime. The level of disturbance is dependent on the local hydrology, geology, and type of mining. Serious damage is sometimes caused by ground water- when mine roofs collapse, causing subsidence. Subsidence is either unplanned, where pillars are inadequate to provide support; or planned, where total extraction occurs over a large area. The primary objective of this study is to investigate the effects of mine subsidence on the ground water hydrology in the Warrior Coal Basin. Underground openings resulting from coal mining activities have been the most significant cause of subsidence problems in the Warrior Coal Basin, the main source of coal in Alabama. This problem will be even more serious in the future because 19 of Alabama's 24 billion tons of coal reserves are classified as an underground source (Tolson, 1982).

Jan 1, 1987