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By John W. Crawford

The title of the paper which I have been asked to present is somewhat misleading it infers in fact that there is a definite coalbed height below which raps or canopies cannot be applied to electric face equipment. Although this may be so with regard to certain pieces of existing equipment under certain conditions, to date we do not have enough experience to determine this magic number. Therefore MESA is continuing to hold the line on the time frames stipulated in Section 75.1710-1 of the Mandatory Safety Standards - Underground Coal Mines, which at this point in time requires these protective structures in mining heights of 60 inches or more. In order to give you an idea why we are taking such a firm stand on this matter, I believe it is necessary to describe some of the background work that was done prior to promulgation of the regulations and to give a resume of our experience since the requirements have become effective. Initially MESA made field investigations of all underground mines to determine what the state of the art was in the use of cabs and canopies for protecting equip¬ment operators from falls of roof. These studies revealed that the application was basically in its infancy and what progress had been made was due to the impetus of the mine operators themselves. Manufacturers of electric face equip¬ment provided these structures only on the direct order from the mining company and built them to their specifications. In talking to the operators and the miners in mines where cabs or canopies were in use, it was the consensus that these structures did improve safety and that although originally there was some reluctance on the part; of the miners to work in the confines of a cab or canopy, mast would not work without them once they had been adapted to the equipment.

Jan 1, 1975

By Hagh H. Bein

MOST mining engineers and geologists realize the value of photographs in their professional work. Members of each group use photographs to illustrate their reports, and articles and photographs, when available, will often save many words of written text in explaining some point or in proving some pet theory. No one hesitates to take aboveground pictures but many rarely take their cameras underground. However, underground photography, too, is really simple. I do not believe that anything new is offered here and the procedures given are merely a compilation of various methods I have tried and used, with some success, over the past six or seven years. The article will deal with photographs to be taken in metal mines, but only in those where no gas hazard exists, with resultant danger of explosions and fire. Some mining company geologists consider the camera a necessary part of their equipment and carry one on their daily trips to the various parts of the mine under their observation. I know of one company whose files of geologic sketches of heading, backs. and veins are supplemented by actual photographs so that a nice geologic picture

Jan 1, 1945

Please note all Proceedings of the Institute were taken verbatim by stenotypists from Hyatt & Associates of Denver and editing has been minimal. MR. MORTENSEN: On behalf of the Rocky Mountain Coal Mining Institute, I take great plea¬sure in saying good morning to you at Vail. With a few clouds in the sky, at least we won't get sunburned. We won't have to worry about our kids in the swimming pool, perhaps. It is delightful for me to have been able to have represented the Rocky Mountain Coal Mining Institute for the year 1982-1983. This has been our 71st year and this is our 79th meeting. In recognizing the attendance here, that dinner we had last night, and some of our entertainment must have gotten to some of us, or it is a little early. But I'm sure as the day goes on, and with the speakers outlined, it will be very beneficial for those who do attend. We do appreciate your attendance. I'd first like to make an introduction of our head table. Doris Finnie, she is our executive secretary. As most of you are aware, Gussie Whiteside retired as secretary. This will be the first time since the Institute started that there has not been a Whiteside present at one of our conventions. I'm sure Gussie would appreciate any calls or letters that any of you would care to make to her. Doris, I might add, has been a great help to me and all of the people who have been working on the program for the Institute this past year. There's been lots of reorganization and we are very pleased with Doris's ability to take hold from Gussie without any waves. Much credit must be given to you Doris for this and we do appreciate the help you have given us and believe me she has kept us out of trouble. Next, we have Art Neill. He is our vice president of the Institute from Montana and he also works with Western Energy Company. We appreciate the help that all of these session leaders and chairmen give to us. We have other names on the head table, but they will fill in as the morning goes on, so we won't bother you with any of those at this time. To set the stage for business, first I would like to call on Doris for a motion to approve the minutes of last year. MS. FINNIE: Thank you, Vernal. Mr. President, I suggest that the reading of the minutes be dispensed with and that the members refer to pages 9 through 80 of the Proceedings for the 78th regular meeting of RMCMI, as published MR. MORTENSEN: Thank you, Doris. Do we have a motion to so approve? MR. LINVILLE: I so move. MR. MORTENSEN: Loren Linville so approved. Do we have a second? MR. GARR: Second. MR. MORTENSEN: All in favor say aye. (Audience responded affirmatively.) MR. MORTENSEN: Those opposed? Hearing none, the motion is carried. I'm sure glad we didn't have to read those 80 pages. Is Doug Hammer in the audience? He was going to give us a list of new members of the Coal Institute and ask for your approval. But because of his absence, the names will be listed so that you can read them at a later date, I will entertain a motion that we approve the new members who have joined the Institute. Do I so have a motion? MR. BERNSTROM: I would make that motion. MR. GARR: I second. MR. MORTENSEN: Do we have any questions? All in favor¬ (Audience responded affirmatively.) MR. MORTENSEN: Any opposed? Hearing none, the motion is carried. Next, we'd like to proceeed with our Nominating committee report from the chairman, George Nugent, and the election of next year's officers. George, would you please take the stand? MR. NUGENT: Mr. President, and members of the Institute, your Nominating committee consists of five past presidents of the Rocky Mountain Coal Mining Institute. From Colorado Roy Coulson; from New Mexico, Bob Wilson; from Utah, Bob

Jan 1, 1983

By H. B. Freaman, C. L. Colburn, C. M. Bouton

"The mine telephone has been perfected to such an extent that it is giving satisfaction in most mines were the wiring is well insulated. Very often the telephone cannot be depended upon on account of falls of rock, grounding due to worn insulation or extreme dampness. In the event of a disaster it frequently happens that the mine telephone system is put out of commission by the agency that causes the disaster, at the time when it is most urgently needed. On this account the mining industry is interested in any kind of telephone system that can be counted upon in an emergency. Many requests have been received by the Bureau of Mines to devise means of utilizing wireless methods for this purpose.The results of some preliminary experiments conducted by the writers at the Bureau of Mines experimental mine at Bruceton, Pennsylvania, in the ordinary sending and receiving of radio waves through earth strata are described below. The experiments were made in cooperation with the Westinghouse Electric end Manufacturing Co., which assigned to this work three of its radio engineers, C. A, Boddie, E. C. Douglas, and F. D. Fessler,The preliminary experiments consisted first in receiving signals from without the mine by means of a receiver located inside the mina, and second, both sending and receiving messages underground through the strata. It was found that with a receiving instrument set at a point 100 feet underground, signals from KDKA station, of the Westinghouse Electric and Manufacturing Co. East Pittsburgh, Pa., could be heard distinctly. Station KDKA is at a distance of about 18 miles from the experimental mine. About 50 feet from the receiving station used in this test was a 6-inch bore-hole from the surface, lined with iron pipe and containing electric light wires which extended therefrom through-out the mine. The presence of these wires evidently assisted greatly in the reception, for when the receiving set was carried to another point in the mine removed from wires and tracks the signals were barely audible through 50 feet of cover. The fact that signals were detected, however, even though faintly, is sufficient evidence of transmission through the ground to encourage further experimenting.In sending waves underground the Westinghouse 20-watt B.T. model T.F. transmitter was used in such a manner as to send out continuous waves of 200 to 300 meters length."

Oct 1, 1922

By Thomas H. Heine

"The Rabbit Lake uranium deposit is located at 58° 11’00”N.. 103°42'36""W., close to the west side of Wollaston Lake, and approximately 800 km north of Saskatoon. The orebody is hosted by Aphebian Wollaston Group rocks, initially deposited as a series of shallow-water marine sediments consisting, in part, of carbonates and possible saliferous petites. Metamorphism during the Hudsonian Orogeny, peaking at about 1850 Ma, recrystallized the sediments to upper amphibolite grade paragneisses. This was accompanied by partial anatexis. The waning stages of Hudsonian orogenesis appear to be marked by minor granitic intrusive activity.The post-Hudsonian period was marked by a long interval of physical and chemical erosion, resulting in the unroofing of the Wollaston metamorphic complex. The entire region underwent extensive lateritic weathering under tropical to subtropical conditions. Carbonates were especially vulnerable and, in the Rabbit Lake area, suffered extensive solutioning with accompanying formation of collapse breccias. Old zones of weakness also underwent periodic reactivation.It was during this period that uranium was leached from the surrounding meta-sediments by oxidizing meteoric waters, and transported into the karsted and fractured rocks of the Rabbit Lake doline.Athabasca Group sediments eventually covered the deposit, their diagenesis taking place at about 200 °C and 900 bars. This allowed the partial to complete recrystallization of the initial mineralization, resulting in a minimum age of 1281 ± 11 Major ""first""-generation pitchblende. Periodic fault/fracture reactivation modified the hydrologic regime within the deposit, resulting in episodic mobilization and recrystallization of pitchblende and other uraniferous species. This is clearly shown in the open pit at the present time: uranium is being mobilized and recrystallized on damp pit walls as bayleyite and liebigite due to the modification of the hydrologic system by mining activities.The uranium mineralization occurs mainly as fracture fillings, coatings, and impregnations within breccia zones and intensely altered metasediments. Lesser mineralization is intimately associated with phyllosilicates which form the matrix of a carbonate-col/apse mega-breccia. The primary ore mineral is pitchblende, consisting of five generations, and from which a large suite of secondary uraniferous minerals have formed. On a gross scale the metal content of this deposit appears to be simple, consisting almost exclusively of U, but minor Ni, As, Cu, Se, Fe and Co are also present. The eastern limit of the mineralization is defined by a vertically-dipping microgranite dyke - breccia complex, containing high-grade uranium values. The orebody is truncated to the west and at depth by the Rabbit Lake reverse fault. Minor mineralization occurs as fracture fillings in unaltered plagioclasite in the footwall of the ore body. Precipitation of uranium from solution could have taken place by a number of processes. A mobile reductant (methane, carbon dioxide, etc.) may have been generated from graphite present in some of the host rocks of the orebody. Sulphides are also a common accessory and may have aided in the formation of a reducing environment. Phyllosilicates may have acted as adsorbants for uranium, allowing for its fixation. This metal has also been incorporated into the phyllosilicates themselves."

Jan 1, 1986

By Paul M. Tyler

Mineral raw materials, because they are essential to our industrial prosperity and military strength, must be made available in substantial quantities regardless of cost. Variations in the cost of procuring minerals, as compared with the cost of obtaining other commodities, and changes in the cost of production of different minerals relative to one another, will naturally influence the quantities of a given mineral item that can be marketed readily. However, in the last analysis, the cost of winning minerals from the ground usually constitutes only a small fraction of the value of the end-use products and services derived from them. The miner's share of the cost of a typewriter, telephone circuit, or even a modem office building, is almost insignificant. Far more important to the ultimate consumer, therefore, than any minor saving in cost is the assurance of ample supplies of the minerals needed to aliment our expanding economy. To create a successful metal mining operation involves (1 ) the discovery and systematic development of a mineral deposit, (2) extraction of the ore, (3) the mechanical and metallurgical processing to eliminate worthless or harmful impurities, and (4) the profitable disposal of the product. The fist step of the technological process belongs chiefly in the realm of the geologist, the second is a mining engineer's job, the third is mainly up to the millmen and extractive metallurgists; whereas the fourth and equally important step poses a commercial problem that has aspects in common with the marketing of other products. Ore finding is far from being an exact science. There is no mathematical criterion for evaluating the efficiency of prospecting and exploration. Lady Luck shares the honors or assumes part of the blame along with the prospector and geologist. Marketing like- wise involves factors that seemingly defy engineering analysis. Although the other steps can be measured with some degree of mathematical accuracy, even they tend to vary so widely in basic principle, as well as in

Jan 1, 1964

By L. A. Schrider, J. A. Wasson

A method of predicting waterflood performance has been developed that combines certain facets of several previously published prediction techniques. The manner of combination has required the development and use of some new and some little-known relationships and has eliminated several of the weaker assumptions inherent in the original individual prediction methods. This approach, which was designed for computer solution, has removed the necessity of referring to plotted curves and permits the analytical prediction of water flood performance for a five-spot well pattern in either homogeneous or stratified reservoirs. The Predicted values are expressed in common oilfield units rather than in abstract or dimensionless terms. The calculation procedure has been programmed in FORTRAN IV and the entire program listing is available to potential users.* Introduction Prior to initiation of secondary recovery of oil by waterflooding, the possibilities of economic success or failure must be evaluated with the greatest practical accuracy. Although many prediction techniques are available, most, if not all, have serious limitations. In recent years, the Bureau of Mines has attempted to stimulate interest in the secondary recovery of oil from Appalachian pressure-depleted reservoirs. Waterflooding, because of its widespread acceptance and success, is the principal secondary-recovery method considered. During the life of the project, several performance prediction methods have been studied and applied. Because these methods, individually, have inherent assumptions and limi-tations, portions of some of them have been selected and combined in an effort to eliminate such shortcomings wherever possible. We believe that the resulting technique is as accurate as the necessary available data will permit and that it has several distinct advantages over previously published methods. Development of the Method The fractional flow equation developed by Buckley and Leverett' from Darcy's law is the fundamental mathematical statement describing immiscible fluid-fluid displacement in porous media. A generalized form of this relationship, whose derivation is readily available in the literature, is The formation dip, a, is usually very small in those petroleum reservoirs being considered for pattern waterflooding in the Appalachian area. Therefore. in many cases. a has an almist negligible value. In addition, Ap, the difference between the density of water and the density of oil, is relatively small. For these reasons the gravitational term may often be neglected. Capillary pressure is a function of saturation, which is in turn a function of distance from the upstream boundary of the system or the injection well. In this study it is assumed that the frontal zone of the waterflooding (or zone of capillarity) has negligible length and that only those saturations in the water-swept zone at breakthrough and later are of interest. As the distance in a waterflood pattern is comparatively large and the change in water saturation with distance is usually small, the change in capillary pressure with distance is negligible. The simplified form of the fractional flow equation is appropriate, therefore, in this application. Three variables must be considered in determining that fraction of the total fluid flow that consists of water: the viscosity ratio, saturation, and relative permeability ratio.

Jan 1, 1969

By J. E. Dreier, R. E. Scheffel, A. Guzman

"This paper outlines a comprehensive, cost-effective testing program for the acid-ferric sulfate heap leaching of oxide, supergene and primary copper ores. It is based on extensive experience in copper heap leaching and uses the many technological advances in the field developed over the past several decades. The approach described requires firstly a detailed resource evaluation, then a hydrodynamic characterization of representative samples and, finally, a focused metallurgical testing program. The principles communicated here can be applied to other acid leachable minerals. The program varies considerably from conventional testing in its disciplined, orderly, step-by-step approach, its application of hydrological and chemical principles to leaching, and its reliance on fewer, more tightly controlled column tests. The purpose of the test program is to optimize the financial, time and other resources devoted to the program, while minimizing the financial risks to the development company or companies and the project funding providers. IntroductionThe major goal of any process development testing program should be the successful implementation of the project. With respect to heap leaching, the metallurgical testing program plays a critical role in the larger objective, as described in Scheffel (2013, 2014). McNulty’s series of papers (1998, 2004, 2014) confirm that the success of any project is directly proportional to the extent and quality of the testing program on which the process is designed.Therefore, a key development objective is to conduct a well-focused metallurgical test program. While the primary focus of this paper is copper, the acid leaching of any substance would benefit from a similar approach.This paper addresses primarily the sulfate system, which is compatible with the bioleaching of sulfide minerals. Nicol et al. (2011) described the advantages of the chloride leaching of copper sulfide minerals. United States patents Nos. US 2009/0173188 A1, US 8,597,933 B2 and US2015/0232963 A1, assigned to BHP Chile Inc. and BHP Billiton S.A. Ltd, describe methods for both the oxidative and nonoxidative leaching of primary and secondary copper sulfides. Reyes (2013) and Ipinza and Flaquer (2014) described commercial applications of chloride-based heap leaching. The testing disciplines discussed in this paper will also apply to the development of an acidic chloride leaching system."

Jan 1, 2016

By J. D. Miller

Flotation chemists have long sought to unravel the mechanisms of carboxylate collector adsorption by semi-soluble salt minerals. In particular, the adsorption density of adsorbed carboxylates, adsorption kinetics, speciation (chemisorbed, physisorbed), orientation, and conformation are of interest. Given the importance of these phenomena in establishing the hydrophobic state at a mineral surface, in-situ surface spectroscopy studies certainly are justified. Such measurements traditionally have been difficult to perform. However, beginning in the late 1980s, a Fourier transform infrared (FTIR) spectroscopic technique was developed that has allowed for the acquisition of a wealth of detailed information concerning carboxyiate adsorption in semi-soluble salt flotation systems. The technique, internal rejection spectroscopy using single-crystal internal reflection elements, is reviewed, as it applies to semi-soluble salt flotation systems.

Jan 1, 1999

By Carl Benedicks

IT is well known by every one who has had to deal with boiler tubes that these are often seriously affected by a sort of corrosion, occurring as a local pitting, that frequently causes a perforation of the tube in a rather short time. The characteristic appearance of this corrosion is shown in Fig. 1. A very similar corrosion occurs in condenser tubes (Fig. 2).1 A study of the microstructure or local chemical composition of the metal (iron; 70 :30 brass) fails to reveal any cause for this pitting. Of course one might possibly assume the starting point-to be some oxide particle, causing an electrolytic local action, but this in no way explains the continued corrosion, progressing even when the assumed oxide particle must have disappeared. By the excellent work done by the Corrosion Research Committee of the Institute of Metals, and communicated, in October, 1923, to the Institution of Engineers and Shipbuilders in Newcastle-on-tyne, stress was laid on the fact that a content of entangled air has a very obnoxious effect. In the following correspondence, Sir George Goodwin stated that "engineers have, for a long time past, regarded air as the big enemy to be fought against in all questions of corrosion"2 and Kenneth Fraser pointed out that the most vital point is "the avoidance or removal of possibly the chief cause of present day corrosion, i. e. entrapped air and gases brought out of solution."' In their reply, however, the authors state that they had "never for a moment believed that entangled air was responsible for the beginnings of corrosion, and express the opinion that the gradual liberation of air could not account for localized corrosion."4 On consulting the many textbooks on corrosion, as that

Jan 4, 1925

By Milton Williams

A comparison is made between the amount of interstitial water found by analysis in cores and that estimated from the resistivity curve of the electric log for the corresponding strata of producing reservoirs. It is shown that while the determined and the estimated water saturations are in good agreement in some cases, this agreement may be due to a fortuitous compensation of errors. Estimates of water saturations made from the electric 1og by use of existing relations should, therefore, be employed with caution. Also presented are data on the variation of salinity of interstitial waters in reservoir sands, and on the effect of variation of salinity and porosity on the validity of estimates of water content made from the electric log. INTRODUCTION Throughout the history of electric logging there have been recurrent cycles of optimism and pessimism as to the value of the electric log in the quantitative estimation of reservoir fluid content. The very early days of electric logging were an optimistic period, in which there was widespread faith in the ability of the resistivity curve to reflect fluid content, and in the ability of the potential curve to indicate textural characteristics. In time the accumulation of exceptions to this idealistic behavior brought about a general disillusionment, and caused the more pessimistic of those dealing with electric logs to believe that the sole importance of the log lay in stratigraphic correlation. Within the last several years optimism as to the quantitative use of the electric log has been revived, primarily as the result of the stimulating work of C. E. Archie' on the estimation of interstitial water in sands from resistivity data. Even though the general trend of thought on the quantitative value of the electric log reflects optimism, it is inevitable that there are some widely divergent opinions of the validity of quantitative estimates based on the electric log. A valid method of estimation of fluid content by means of the electric log and a general knowledge of the textural character of the reservoir rock would be of signal importance, not only in that it would save time and money in securing information on reservoirs now being drilled, but also because it would permit the evaluation of reserves in many fields drilled without adequate core data subsequent to the advent of electric logging. Because of this importance, Humble's Production Research Division, in cooperation with various other company divisions, initiated several years ago series of tests designed to evaluate the reliability of estimates of fluid content made from the electric log. The investigation was limited at the outset to sand reservoirs, since it was felt that the inclusion of limestone reservoirs would entail needless complications. In devising these tests it was immediately apparent that the chief difficulty in evaluating the worth of any method of estimation lay in establishing the true value of fluid content. The results of direct analyses of cores cut with ordinary mud were not sufficient, because of the probability of contamination of the fluids by filtrate from the drilling mud; the results of restored state tests on cores were deemed unsuitable because these results can hardly be said to furnish a primary standard. The method adopted was the direct analysis of cores cut with an oil-base drilling fluid. Such cores, when properly handled, are believed to afford the most precise determination of water content available at the present, and, in addition, lend themselves readily to the determination of various other properties which are pertinent to the estimation of fluid content from the electric log. Since it was desired to compare the fluid contents estimated from the electric log run in ordinary mud with cores cut in the same hole, the use of oil-base fluid necessitated the changing over, after all cores were cut, to a conventional mud. This procedure presented several advantages, one of which was that the use of oil-base fluid permitted

Jan 1, 1950

By N. Del Bel Belluz

Drilling underground in the Grasberg De-watering drifts has routinely hit water aquifers with high flow rates and pressures. Two types of holes are utilized; pilot-holes to probe ahead of the tunnel development to intersect aquifers ahead of the face; and de-watering holes to de-water rock formations that will drain water from the Grasberg pit and allow tunnel development to proceed safely. Recently, rates of 1050 psi static pressure have been recorded with flows from a NQ hole measured at 1350 gpm (US). The water flows can be slightly acidic, necessitating the use of stainless steel collar gear to resist corrosion. These rates were anticipated and contingencies were planned early to deal with these conditions. The collar gear is used to control water flows whereby the water is treated as an important resource. As a result, pm has established procedures to maintain safety of the drill crews, enable coring of the rock and to maintain safety of the miners who are driving the drifts.

Jan 1, 1998

By G. M. Humphrey

It is a great honour and privilege to be here in this distinguished company of the outstanding men in the mining industry and the political life of Canada. I fully recognize that I am so honoured as a symbol of the combination of American and Canadian leaders in industry who are partners in the sponsor-ship of the Quebec-Labrador iron-ore mining development which we are undertaking, and as such I want to express our great appreciation of the co-operation and assistance we have met on every hand in Canada, and the genuine friendliness and never-failing courtesy which we are always accorded. We are quite aware that it springs primarily from the very high regard in which our partner and sponsor, Jules Timmins, and our other Canadian associates are held. Their high standing among you is well known and we quite naturally fall heir to the benefits of the great esteem in which you hold them. Jules Timmins and his long-time associate, John Knox, were the original inspiration for our participation in this venture. It was their enthusiasm and vision which caught our interest and led to our joining with them in the years of exploration and search which have brought us to the threshold of this great development where we stand today. So much has been written of the details of our exploration and plans for future development that it would bore you for me to review them further here, but there is a phase of this development, and an extremely important phase of it, which I think has passed almost unnoticed and which it may be well worth while for me to bring to your attention this evening.

Jan 1, 1951

By William Fink

ALUMINUM forms not only binary compounds with most of the metallic elements but also forms many ternary or more complex constituents. Several of those occurring in the more important alloy systems have been identified under the microscope and the action of various etching reagents has, been carefully studied.' The determination of the structure and composition of these complex constituents is a matter of some difficulty and little information is available. X-ray crystal analysis offers a promising method for the study of such constituents. First, and of considerable importance, is the possibility of recognizing the presence of a given constituent by means more positive than microscopic observation. Evidence can also be obtained concerning the nature and composition of the constituent in question and ultimately it should be possible, at least in some cases, to describe the structure including the relative locations of the various atoms. In this paper some results of an uncompleted study of the constituents of the aluminum-iron-silicon system are given and the methods employed are described. Inasmuch as iron and silicon are the chief impurities in aluminum, the constitutional relations of this system are of fundamental importance in the metallurgy of pure aluminum and its alloys; the system has been studied by several investigators and the more important contributions have been reviewed recently.2 Fig. 1 shows the structure of the aluminum-rich alloys after prolonged annealing at 560° C., in accord with one of the most recent investigations.3 The ternary alloys examined in the course of the present investigation were all annealed at 550° or 560° C.; in fact, some of the specimens were the identical ones used by Dix and Heath, who kindly supplied them for this work. Since the results

Jan 1, 1930

By Sheard SN, Tucker DH

Sampling procedures are an important aspect of geophysical exploration survey design. It is good practice that the selection of survey parameters ensures that the signal to noise ratio is optimised, while minimising survey cost.Sampling considerations for any geophysical method include the size of the target, scale of observation, aliasing associated with station and line spacing, nature and extent of overburden, and the presentation of data.As a guide to survey design, the specifics are discussed for three geophysical techniques in common use in mineral exploration; these include the magnetic method, transient electromagnetics and induced polarisation.

Jan 1, 1976

By J Benn, V Kuznetsov, G Timms, A Spain

Earthen covers are now widely used in the mining industry to control the generation rate and/or release rate of low quality drainage from piles of sulfidic minewastes. Covers are usually designed to reduce the water infiltration rate and in some cases may also reduce the oxygen flux to the underlying sulfides. Engineered covers have only been used since the 1980s, however, and there is very little field data on their performance in the longer term. This lack of information has implications for the degree of confidence that can be placed on the predictions of the environmental impacts of sulfidic minewastes, for the acceptance of close-out criteria by regulatory authorities and for the financial liability of the mining industry. Covers were placed on sulfidic waste rock dumps at the abandoned Rum Jungle uranium mine during 1984 - 1985. These covers were designed to reduce the water infiltration to less than five per cent of incident rainfall by both water shedding and storage-release mechanisms. Regular monitoring by the Australian Nuclear Science and Technology Organisation (ANSTO) demonstrated that the covers performed better than the design criterion for around ten years, but infiltration rates have subsequently increased. There is a 66 per cent probability that the infiltration rate now exceeds five per cent of incident rainfall. The cover on the largest pile, WhiteÆs heap, was sampled in pits dug at eight locations. Sampling was carried out at the end of the monsoonal wet season and again at the end of the ædryÆ season. This, together with laboratory testing, enabled cover performance to be assessed against five criteria: design, construction, cover material characteristics, physico-chemical characteristics and biological characteristics. We are of the opinion that the design of the cover was suitable to achieve the objectives of stability, water shedding, storage-release, and provision of a substrate for vegetation growth. Over most of the surface of the heap, the construction of the covers, drains and erosion prevention structures was in accordance with design specifications. However, several small and localised bare patches on the upper surface of WhiteÆs heap coincide with a reduced cover thickness, which is likely to have been due to poor construction in those patches. The construction of covers on minewastes is dependent on an adequate source of material meeting design specifications. From our limited examination, it appears that there was shortage of material for each of the three zones û a lower impervious clay layer, the moisture storage-release layer and the upper erosion-resistant layer for vegetative growth. An indication of this was that the upper layers in some areas were observed to be thinner than specified. We are of the opinion that this shortage of suitable material has been responsible for some of the changes observed ten years after emplacement. Physical and geotechnical testing indicated that the cover materials no longer meet the original specifications. In particular, the permeability at the 8 locations was found to be greater than specified, by up to several orders of magnitude. The higher permeability may explain the higher observed rainfall infiltration and moisture content of the waste rock. This increased permeability appears to be due to a combination of biological and physical processes û galleries formed by termites and ants and an extensive system of shrinkage/desiccation cracks formed by the development of a polygonal blocky structure involving the entire lower clay layer. The desiccation cracks may fill with coarser illuviated materials and form a conduit through which roots access the underlying waste rock. Measurements were made of oxygen flux into the heap as cover layers were excavated in the pits. They indicated that the full cover currently reduces the oxygen flux to 20 - 23 per cent of that into bare waste and that this reduction seems to be proportional to the cover thickness. It was also found that the oxygen flux into the cover is about four times higher at the end of the dry season than at the end of the wet season and that the difference is due primarily to the difference in moisture content of the cover. Recommendations are made for the design and construction of covers.

Jan 1, 2003

The following is an incomplete list of members and guests who called at Institute headquarters during the period July 11, 1918 to August 11, 1918. John Carter Anderson, Tucson, Ariz. Edson S. Pettis, San Francisco, Cal. Lieut. Frank A. Ayer, Tyrone, N. M. Wm. H. Rettie, Yonkers, N. Y. W. R. Canton, McGill, Nev. J. T. Robertson, Port Richmond, S. I. Alden Crankshaw, Palmerton, Pa. Harry O. Robinson, Margarita, John Davenport, W. Norfolk, Va. Venezuela. A. Faison Dickson. C. K. Seng, Gilbert, Minn. F. A. Fahrenwald, Cleveland, C). E. S. Sheffield. L. Hall Goodwin, New York. H. G. Smith. W. H. W. Hamilton, Baker, Ore. Harry M. Spoor. Floyd D. James, St. Louis, Mo. H. H. Stoek, Urbana, Ill. George A. Laird. Arthur L. Tuttle, Copperhill, Tenn. J. W. McBride, Spokane, Wash. Thor Warner, Phoenix, Ariz. Arthur Notman, Bisbee, Ariz. Christopher G. Atwater, Manager Agricultural Dept., The Barrett Co., is in Washington serving the U. S. Navy Bureau of ordnance in connection with the Navy nitrate plant recently authorized by Congress. Edward Ludlam Blossom announces his marriage to Mabel Townsend, daughter of Mr. and Mrs. George Comings Mills, on Wednesday, July 17, 1918, at New York City.

Jan 9, 1918

By Craig M. Sams

Matching mill? drives to mill power draws is a relatively new practice with the introduction of variable speed drive arrangements. Semi-autogenous grinding (SAG) mills are the focus of this paper as ball and rod mill characteristics are easily charted as charge loading and speed change. In addition, a look at types of drives available in the market and mechanical ratings is outlined to match the specifics of each drive.

Jan 1, 1991

By D. C. Krige

The estimation of the tonnage and grade of payable ore in a mine and the correct policy of selective mining based on such estimates, is of vital importance to the mining engineer it is surprising, therefore, that more attention has not been devoted on the Witwatersrand to the scientific improvement of mine valuation methods. At present these methods consist almost entirely of the application of simple arithmetic and empirical formulae guided by practical experience, and ignore the many advantages to be gained from a careful statistical analysis of the behaviour of the gold values. The science of statistics has expanded rapidly during the last two decades and its value as a powerful and indispensable tool is now recognized not only by research workers and scientists but also, ever-increasingly, by the commercial and industrial world. This being the case it is noteworthy that in a mining field such as the Rand with its highly developed and advanced mining methods, singularly little attention has been paid to the analysis of mine valuation problems on a modern statistical basis. This omission is even more striking when cognizance is taken of the wealth of sampling data concerning the gold ore which is available and of the far-reaching decisions and deductions constantly being based on such data. Some contributions have however been made from time to time towards the application of statistics to mine valuation on the Rand (References Nos. 7, 8, 9, 11, and 12), but none of these have been generally applied in practice and a systematic practical approach based on clearly deemed fundamental concepts still appears to be lacking. The object of this paper is, therefore, to define these statistical concepts and to indicate briefly the lines along which statistical methods can be applied profitability in solving some of the existing problems and in improving the general standard of mine valuation on the Rand For this purpose a knowledge of mathematical statistics is essential, but as this paper is primarily intended to provide the mine valuator with a practical introduction to statistical application in his field, the mathematics is confined to a short annexure, together with references from which details can be obtained.

Jan 1, 1994

By I. H. Warren, F. A. Forward, D. E. Pickett, Ernest Peters, Alvin H. Ross, I. M. Masters, N. P. Finkelstein, R. Derry, A. W. Fletcher

In this section the chemical, physical, and mechanical principles of hydrometallurgical processes are developed and reviewed. Plant practice is not discussed other than to note the metals which are processed using the various systems that are available. These notations will permit the reader to refer to the appropriate section in Part II of the Handbook for specific details on a particular metal or mineral. The equipment used to accomplish the desired unit operation is de¬scribed. Comparative data are presented to illustrate performance characteristics of unit operations, process, and equipment. The economic efficiency of individual processes is outlined. Some of the chapters contain material that is covered in detail in other sections of the Handbook Such chapters are developed only sufficiently to indicate the specific application of the techniques to hydrometallurgical processes. In this section considerable cross-referencing to the other related sections has been done.

Jan 1, 1985