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By S. C. Sun

Most previous work on sedimentation of coal 1 and mineral 2-3 suspensions has been conducted in graduated 1-liter glass cylinders of 6-cm diam. With this type of large container it is often difficult to see through the suspension and tedious to perform a large number of tests. Furthermore, the heavy glass walls and the graduation lines of glass cylinders cause internal and stray reflections, respectively. To obviate these difficulties, an Atlab Emulsion Viewer from Arthur H. Thomas Co. was adopted as an alternative apparatus. Equipment: The viewer," shown in Fig. 1, consists of: 1) a stainless steel frame rack holding 21 flat-bottom Nessler tubes or an ungraduated replica 1.64 cm ID and 1.80 cm OD, 2) a movable masked 150-w lumaline lamp behind the tubes, and 3) a scaled glass panel with 100 vertical divisions in front of the tubes. The tubes are snugly held by springs in slots formed by spacer bars, which also serve as shields to eliminate stray light. The lumaline lamp is mounted behind a slit in a movable housing so that it can be positioned behind the suspension to be examined. The lowest or 100-divi-sion line on the front glass plate is leveled with the upper side of the bottom of all tubes. The scaled portion of each tube, roughly 19 cm high and 40 ml in volume, is used to study coal and mineral suspensions. Procedure: The following procedure was used in many tests. A 1.6-gm sample of dry coal was mixed with 16 ml of distilled water in an ordinary test tube and allowed to stand for three days, with occasional shaking to insure thorough wetting of all particles. The slurry was transferred to a Nessler tube and diluted to 32 ml. The pH regulator and flocculating reagent were added, and the slurry was diluted to reach the uppermost or zero-division line. The tube was immediately stoppered and inverted downward and up again ten times during a period of 35 to 40 sec. The lumaline lamp was turned on during the inversion period. After inversion the tube was quickly returned to the viewer rack. The time elapsed for each 10-division drop of the demarcation line between solid and liquid was recorded by stopwatch until the 80-division line was reached in the zone of compression. Additional readings were taken at 15, 30, and 60 min after settling began. The clarity of the supernatent liquid was observed also. As the settling rate became considerably slower at the 75-division line, it was convenient at this time to start the next test in a separate Nessler tube. This was continued until the suspensions in any number of the 21 tubes were tested. An attempt was made to correlate the experimental results between the Nessler tube and a 1-liter glass cylinder. Table I shows that coal particles settle much faster in the cylinder than in the tube, which has a large wall effect.' The correction factor for the tube impedance is 1.662 2 0.145 at the 40-division line in the hindered settling zone, and 1.614 & 0.139 at the 75-division line in the compression zone. This rough correlation was established by dividing the pulp height of each container into 100 divisions and comparing the settling rates of the two containers at the same divisions. Tests were also performed to determine the accuracy of the viewer. The results, not presented, showed that error was within 10 pct.

Jan 1, 1960

By J. Wesley Atkins

In considering the importance of lease management and administration, I have decided to approach the topic, Lease Default and Eviction: Action or Reaction, as a three phase presentation dealing with mineral lease administration and management, past, present and future. Though the title may border on the dramatic, it illustrates the real consequences of alternative approaches to property management viewed from my experience in the evaluation, development and implementation of a number of such systems and services in my current position as president of Talco Group Corporation. First, though, let's take a moment and set the stage by giving a few actual examples of why a pragmatic approach is needed in this particular area.

Jan 1, 1983

By E. T. Dumble

PROF. EDWARD ORTON, in his Report on the Occurrence of Petroleum, Natural Gas and Asphalt Rock in Western Kentucky, thus clearly states his ideas of the universal dissemination and rare accumulations of the bitumens:1 " We need to bear in mind that the various members of the bituminous series are abundantly and almost universally distributed among the unaltered sedimentary rocks of the earth's crust. The valuable accumulations of these substances are rare, it is true, but one can scarcely go amiss of petroleum, asphalt or gas, at least in small quantities, among the stratified rocks that retain their original structure." Speaking of the Ohio valley, he adds: "A fifth of one per cent. of petroleum, if distributed through a, thousand feet of rock, would make a total to the acre, or square mile far , beyond any production that has ever been realized from the richest oil field, and percentages of this amount are not only not rare to find, but are even hard to miss." Dr. F. W. Clarke in his Data of Geochemistry (Bulletin No. 491, U. S. Geological Survey, 1911), discussing these views of Orton with similar views of T. Sterry Hunt and Szajnocha, says that they "lead to the conviction that the formation of bitumens is a general process and by no means exceptional. Wherever sediments are laid down, inclosing either animal or vegetable matter, there bitumens may be produced."2 The organic origin of the bitumens, including petroleum, has long been an accepted fact with nearly all geologists, but the method, place, and time of the transformation into petroleum or other bitumen is still under discussion.

Jan 3, 1914

By O. L. Kachor, A. V. Bogdanov

"In 2015 in the frames of federal special-purpose program «National system of chemical and biosafety of Russian Federation (2009-2014)» Federal State Budget Educational Institution of Higher Education ""Irkutsk National Research Technical University” (further–INRTU) performed works aimed at disposal of accumulated arsenical residues at industrial site of the former Angarsk arsenical plant (AAP) processing arsenious ores from Svirsk town in Irkutsk region. The plant in 1934-1949 produced arsenic trioxide for the defence industry. Prior to starting the works on disposal of industrial pollution focus the total amount of cinders stored on 13 ha of industrial site of AAP was 156 900 tons with 1% average arsenic content. Close to the cinders there were also remains of industrial buildings and process equipment in the amount of 6 600 m3 that contained 150 tons of arsenic. Additional source of pollution at the industrial site of AAP is contaminated soil amounted to 48 000 tons. Proven reserves of gold and silver in the cinders were 6.1 and 47 g/t respectively. In 2015 the source of arsenious pollution was detoxificated according to mineral matrix technology and stored in a special landfill with separate stocking of gold-containing cinder and other arsenious residues. This technology of waste disposal specifies extraction of valuable metals from cinder in future. The similar case is with Vershino-Darasunsky settlement in Trans-Baikal Territory where the abandoned industrial site of the former arsenic plant is located in the central part of the settlement. The concentration of arsenic and valuable components can be compared to the concentration at AAP. Since 2016 the demand for removal of such industrial pollution sources is legislated due to amendments in Federal Law No. 7-FZ on environmental protection. It results in a real possibility to remove such dangerous industrial residues deposits as the one located in Vershino-Darasunsky settlement. INTRODUCTION In the frames of federal special-purpose program «National system of chemical and biosafety of Russian Federation (2009-2014)» as well as the Irkutsk region program “Environment protection in Irkutsk region"" for 2006-2015, INRTU performed the works aiming at disposal of accumulated environmental deprivation–arsenical residues from the former Angarsk arsenic plant (further - AAP) (Figure 1) on processing of arsenopyrite ores of Svirsk town in Irkutsk regionThe plant produced arsenic trioxidein 1934-1949."

Jan 1, 2018

Jan 1, 1927

By Maxwell Adams

CONSIDERABLE interest has recently been developed in sage-brush oil because of its possible utilization as a flotation agent in the mining industry. A list of some of its physical properties, together with the method used in its extraction, may prove of interest at this time. Something over a year ago, a study of the essential oils in desert plants was begun in the Chemical Laboratory of the University of Nevada. None of the oils so far studied possess properties of special interest to engineers, except the oil of sage, Artemesia tridentate, which has exceptional power as a flotation agent. This plant, known as common sage brush, also called black sage, is widely distributed over the semi-arid West, being found quite generally on most of the dry plains and mountains west of Missouri. The method of extracting the oil followed in these experiments is very simple. The leaves, twigs and small branches are placed in an airtight drum, having a capacity of about 27 cu. ft. Steam is admitted through a number of small openings at the bottom of the retort, and the pressure maintained at 20 to 25 lb. per sq. in. for 3 hr. The escape of the steam from the retort is regulated by allowing it to pass through a stop-cock into a condenser. The water in the receiver is drawn off from time to time and the oil, which is insoluble and floats upon the water, is thus collected. At the end of 2 hr. most of the oil has been driven out, though traces continue to come over for a much longer time. By raising the pressure, the time required could probably be shortened and the yield increased, but the lack of laboratory equipment has prevented the carrying out of this experiment.

Jan 9, 1916

By Harold M. Mooney

WHEN apparent resistivity data are taken with the symmetrical Wenner 4-electrode spread, a fixed center position is used and readings are taken for values of electrode separation. Basic data consist of apparent resistivity plotted against separation of adjacent electrodes . The interpreter attempts to infer geologic structure, such as the depth to discontinuities and the nature of subsurface earth materials. An earlier paper' described methods for interpreting resistivity data. All of these involve a severe assumption, namely that the earth in the region of interest consists of horizontal layers, electrically homogeneous and isotropic. The actual earth never satisfies this assumption exactly and may deviate from it so much that none of the above methods can be applied. Attempts in three directions have been made to modify the assumption so that it approaches known geologic complexity more closely. First, curves have been calculated for dipping discontinuities. Stern' and Aldredge hose a few widely separated dip angles. Trudu confined his attention to small dips. Berel'kovskiy and Zubanov computed gradient curves for widely separated dip angles. Unz as given the most complete solution, with a brief attempt to treat the three-layer case. Second, anisotropy can be taken into account. It seems geologically probable that layered materials have different vertical and horizontal conductivities. Cagniard, Maillet, and Pirson et up methods for finding an equivalent hypothetical isotropic medium. Standard interpretation methods can be applied to this, and the actual medium can then be deduced. Belluigi'" discounts the practical importance of anisotropy; Geneslay and Rouget do not agree with his conclusion. Third, the effect of variable resistivity in a layer can be considered. Keck and Colby" examine the mathematics of an exponential increase in a surface layer. Several authors, for example, Stevenson,'' consider a continuous variation of resistivity with depth. The present paper deals with a linear variation of resistivity in a surface layer. Geologically, surface variations should be expected. Unconsolidated materials such as glacial drift show marked irregularities over short distances. The effects of weathering change with depth. The moisture content of material above the water table may vary from a dry sand to a saturated clay, and both of these will be changed by rainfall. Figs. 1 to 6 present apparent resistivity curves to show the effect of a variable surface layer. In all cases resistivity varies linearly with depth down to a depth of one unit. Material beneath this depth has constant resistivity. Electrode separation is plotted in depth units. Insets on each figure show the corresponding cross-sections, plotting true resistivity against depth. To illustrate, consider curve A of Fig. 1. The true resistivity of material at the surface of the earth is taken as 0.4 units. Resistivity increases with depth, reaching a value of 1.0 at 0.5 depth units and 1.6 at 1.0 depth units. Below a depth of 1.0, all the material has very low resistivity (zero, for purposes of calculation). Curve A in the main part of Fig. 1 shows how apparent resistivity varies for this case as the electrode spacing is increased. To illustrate further, curve E of Fig. 4 corresponds to true resistivity of 1.2 units at the surface, 1.0 at a depth of 0.5 units, 0.8 at a depth of 1.0, and 1.5 for all depths greater than 1.0. Apparent resistivity curves have been plotted logarithmically so that the shape of the curves becomes independent of the units, giving the curves wide validity. A certain drift-covered area, for example, shows a gradual decrease of resistivity from 230 ohm-meters at the surface to 150 ohm-meters at the bedrock surface, 275 ft down; bedrock resistivity is 800 ohm-meters. Curve E of Fig. 5 indicates that true resistivity decreases from 1.2 units at the surface to 0.8 at a depth of 1.0, then increases abruptly to a constant value of 4.0 units. Since resistivity and depth ratios are the same, this can be used to predict the field curve. For Fig. 5, multiply true resistivity and apparent resistivity by

Jan 1, 1955

By R. E. Somers

1. INTRODUCTION 1. Location, Topography, and Climate The Burro Mountains are located in the southwestern part of New Mexico, in Grant County. The group is made up of two distinct moun-tain masses, known as the Little Burros and the Big Burros, the former lying about 6 miles southwest of Silver City-, and the latter about 9 miles farther in the same direction. They are separated by the valley of the Mangas River, a tributary of the Gila, and a stream only in name, except after a heavy down-pour of rain. . The Little Burros attain an elevation of 6,625 ft. above sea level, and the Big Burros 8,054 ft., with the surrounding country averaging about 6,000 ft. To the south of these mountains stretches the desert plain, while to the north are the more frequent elevations of the mountainous country.

Jan 5, 1915

By A. L. Field

A. W. FAHRENWALD, Socorro, 'N. M. (communication to the Secretary*).-When asked to discuss Mr. Feild's paper, I felt most highly complimented to have the privilege of commenting on such a worthy and needed piece of apparatus. In consideration of the importance of the viscosity of blast-furnace slags and the relation existing between the' melting point of a slag and its viscosity, the introduction of this apparatus should be a welcome means or assistant in the study of the physical properties of a slag. Up to the present time, it is A fact that this side of the practical working of the blast furnace has been sadly neglected by those investigating slags. It is easily seen that the fluidity of a slag is of as great importance as its melting point. It is not necessarily true that a slag having a low melting point will have a correspondingly low viscosity or be highly fluid. For example, a slag having a melting point of 1,100° C. may have to be superheated to, say,1,300° C., in order to have as high a fluidity as another slag whose melting point is, say, 1,250° C. The latter in this case would be the more economical. This point has been brought out very nicely by Mr. Feild. Before discussing this paper further, I think it will be well to outline some of the points, a discussion of which may be in order:

Jan 3, 1917

By N. K. Chen, C. H. Mathewson

Recrystallization of aluminum single crystals after plastic extension is carefully studied in relation to the structure of the deformed matrix. The shapes of the new grains are analyzed with regard to slip planes and to the presence or absence of deformation bands. A mechanism by which the orientations of the grains are related to the parent lattice is described. EXPERIMENTS previously reported&apos; have been extended to develop some of the characteristics of the new crystals which are formed on annealing axially strained crystals whose deformational characteristics had been documented with special care. Thus, the presence of deformation bands affects the growth contours of the crystals, some of the strained crystals produced single crystals anew, and some, polycrystals, on annealing, while others merely "recovered" or "polygonalized" after the 600°C annealing treatment generally adopted in these tests. In the matter of orientational relationships between new crystals and the strained matrix, the present experiments have added little to previous experience, which had demonstrated great variety in the range of orientations encountered and no simple theory or correlation. For example, there has been ample evidence for the predominance in various face-centered cubic metals of a favored orientational relationship; viz., a rotation of 30° to 40° around a <1ll> axis, between grains growing in a matrix with a strong single orientation texture and the matrix itself.&apos;-&apos; This reorientation has been interpreted by various investigators in support of both the "oriented nucleation" and the "oriented growth" hypothesis. In the case of axially extended single crystals of aluminum, no general relationship, such as the one stated above, can be used to correlate the orientations of the recrystallized grains with that of the original crystal. Thus, Carpenter and Elama and Burgers and Basart7 were content to assume that the orientational relationships so developed were random in nature. Mathewson, however, in the Campbell Lecture of 1943 "rgued on the basis of <112> slip that a complex strain, chiefly characterized by rotation around a variable axis in the slip plane combined with a principal rotation around the pole of the slip plane, could be responsible for such devious relationships. Nevertheless, owing to the limited data now available dealing with orientational relationships between new grains and the single crystals strained in tension from which they have recrystallized, no adequate examination of the above generalization could be made. Here, there is the disturbing preliminary condition that any desired orientational relationship may be expressed by means of two rotations about mutually perpendicular axes, so the process lacks a certain critical flavor and any successful choice of axes meeting certain theoretical requirements could be replaced by another differently selected pair. With this reservation clearly in mind the process of double rotations, as previously indicated, was used to relate the orientations of the single crystals which grew out of the strained single crystalline matrix and was construed as certain evidence in favor of the theory of incongruent shearing action proposed by Mathewsons as a necessary element in the (111) slip process with close-packed metals. There is here

Jan 1, 1953

By M. Gershon

Four computerized approaches for coal blending are described and their strengths and weaknesses are explored. Spreadsheet analysis Other than word processing, spreadsheet software is the most commonly used software. Its wide availability and ease of use are two desirable features that have led many to try to adapt it to the purpose of coal blending. These are the two main advantages of this approach. To use a spreadsheet for coal blending, each row of data represents one source of coal. Each column represents a quality of the coal, with the last column specifying the tonnage of that coal in the blend. The calculated figures are the blended qualities, which can be programmed to appear in the bottom row. A trial-and-error approach is then used to develop the best blend. Inserting any blend in the last column provides the blend characteristics at the bottom of the page. If any specifications are not met, the blend can be changed, all calculations being immediately updated. This process is repeated until all specifications are satisfied. A third advantage of this method is that it is exactly the procedure that one would go through if doing this by hand. With a spreadsheet, many more blends can be evaluated in much less time, allowing the designer to try to improve over satisfactory blends to find the best of them. The resulting improved blends or cost savings are a fourth advantage of this approach. There is only one major disadvantage of using the spread-sheet. This is that most probably the best blend is not found. As an inexpensive introduction to computer-assisted blending, which can be easily understood and cost just a few hundred dollars, this is a recommended place to begin. Computerized search Computerized search approaches represent crude first attempts at letting the computer design the blend. Unfortunately, the blends found by these programs are very often less satisfactory than those developed manually. The way these techniques work is that they design, according to some predesigned pattern, a number of different blends and then quickly evaluate them. It is then straightforward to select the best from this sample set. The quality of the results depends on the number of blends designed, the way they differ from each other (the search procedure), the number of sources available, the number of quality specifications, and the severity of the specification limits. Good results are usually obtained for small, simple problems. At best, the results obtained are inconsistent from one blend to the next. Programs of this type are advertised in the mining literature. They usually mention how many different blends are evaluated, making it clear that this is more than can be tried manually. Expert systems Expert systems use a source of information known as a knowledge base. The knowledge base, usually a set of if-then rules, attempts to reconstruct the deductive reasoning process of an expert in some job capacity. For coal blending, the usual trial-and-error process has an easily recognized pattern of rules that are followed to try to find a better blend. By following these rules, it is possible to home in on the best blend without the exhaustive search required by the previous method and without the manual manipulation of the spreadsheet approach. The use of an expert system accomplishes this. One of the rules may say something like "if BTU is out of spec, then add more in the blend from a source having a high BTU and subtract some from a source having low BTU." In other words, it goes through the trial-and-error process. The process continues until all specifications are achieved and can continue further to try to optimize the cost. Of course, less simplistic rules are also needed. One set of rules would determine maximum changes in the tonnage added or deleted to the blend or from any one source. Other rules would be needed to determine which quality to improve if two or more are out of spec. At this level, the process of building the knowledge base provides the engineer with a deeper understanding of his or her own thought processes. The advantage of obtaining better blends is clear for this approach. Two more advantages should also be apparent. One is that it follows the same common sense logic that is used when doing the blends by hand or by spreadsheet, making it easy to understand. The other is that, like the search procedure, it designs the blend rather than just analyzing manually designed blends. Thus, it has all the good features of both approaches discussed thus far while providing improved results over each. A final advantage is the ease of use and ease of development. The expert system shells that are on the market are very easy to use and can be run on microcomputers. Linear programming Linear programming is an algebraic tool that solves a set of linear equations to yield an optimal solution to a problem. The optimal solution is based on the linear model so the results are only as good as the ability of the linear model to accurately portray the reality of the problem situation. It is fortunate for the coal blending problem that a linear model can be devel¬oped that reflects exactly the problem that is required. Unfortunately, the mining industry has been slow to use this tool. Coal blending applications available that use linear programming take one of three forms. The first, requiring exper-

Jan 12, 1988

By D. Collins, B. Pina, G. Snell

The conversion of moisture and ash free (maf) coal to pyridine solubles and gas was investigated in a microautoclave batch reactor. Two washed Kentucky coal samples (KY # 9 and KY #11) were studied in liquefaction solvents of various donor strength. The liquefaction solvent hydrogen donor strength was varied by changing the tetralin content of a mixed 1 -methylnaphthalene-tetralin mixture. Primary liquefaction conversions in excess of 90 wt% in 10 minutes of reaction time @ 700° K (427OC or 800°F) were achieved with liquefaction solvents of moderate donor strength, i.e. 40% tetralin. A modified irreversible first order rate expression (eq. 1) described the experimental data:

Jan 1, 1986

Introduction and Background For many years people were aware of the vast deposits of titaniferous magnetite containing vanadium in the Bushveld Complex. From 1957 onwards some exploitation of this ore was carried out by Minerals Engineering of S.A. (later the Vantra Division of Highveld Steel and Vanadium Corporation Limited), who produced vanadium pentoxide via a roast-leach process. Canadian Institute of Mining and Metallurgy The Finance and Executive Committees of the Canadian Institute of Mining and Metallurgy have agreed that members of SAIMM should be invited to register at all future CIM meetings at the same rate as CIM members.

Jan 1, 1980

Jan 1, 1926

By David Hoadley, Kenneth R. Maser, Ashok B. Boghani, James E. Billar, D. Randolph Berry, Mackenzie Burnett, Robert H. Trent

B 6 Listing The following is a listing of the Mine Evacuation Simulation Program

Jan 1, 1976

By William P. Blake

THE use of diamonds upon a large scale in drilling rocks, and the substitution to a certain degree of rotary diamond drills for the ordinary steel percussion drills, marks a new era in the art of mining. Since the invention by Leschot of the diamond drill, it has steadily advanced in its utility and range of application, and in the appreciation of miners and engineers. I t must be claimed as one of the many gifts of science to the arts ; and it is, in particular, one of the fruits of the scientific education given at the Ecole Centrale, at Paris. Members are all, doubtless, more or less familiar with the construction of the drill and of the machinery by which it is applied in boring. I t is, therefore, my present purpose only to direct your attention to some recent marked improvements, made by the American Diamond Drill Company, by which the economy and efficiency of the machines have been increased. Form of Bit.-The annular or ring form of the drill-head or bit was, I believe, the earliest; and it is still in use, without essential modification, wherever it is desired to obtain a sample " core" or specimen of the rock traversed. But for mere drilling, regardless ~f the preservation of a test-core, a solid-head bit is preferred, except for very large holes. Until recently, these solid-head bits were made with a pointed cutting face shaped like an obtuse cone. This form was assumed to be the best, being most in accordance with the experience obtained with percussion drills. I t is found, however, that the exact reverse

By F. W. Jessen

The Mechanism of solution of salt and mixed halites of sodium and potassium is reviewed. The variation in the rate of salt removal under both laminar and turbulent flow conditions is discussed. Many changes are possible in the development of solution cavities whether used for production of salts or for storage of hydrocarbons. The parameters influencing the type and shape of cavity formed with single well or multiple well systems are examined and information presented regarding field application of techniques developed and the means of controlling overall configuration of solution cavities.

Jan 1, 1972

By J. T. Bartlett

Life-of-mine process simulation is an interdisciplinary effort and a useful means of thoroughly evaluating mining and minerals projects. Communication between geologists, mine planners, miners, metallurgists, and managers not only benefits each discipline but facilitates design of an efficient operation and allows for accurate forecasting of productions and cash flow. By focusing on the key areas: geology; mine design; waste dumps; stockpiles; metallurgy; weather data; tailings disposal; using contours, block models, mine plans, process flowsheets, design criteria, operating and control strategies, maintenance schedules, and operating costs to perform detailed daily simulation from start-up to shut-down; a comprehensive understanding for all disciplines is achieved. Construction of a METSIM model that includes all test work and project data from drill holes through net present value calculations brings the pieces together to achieve optimum process design, minimize operating problems and eliminate the term ?black box? from project meetings and discussions.

Feb 27, 2013

By O. A. E. Jackson

In all three principal dunite dikes, minute disseminated grains of pyrrhotite are to be seen in the fresh rock in amounts less than 1 pct. Traces of nickel have been reported from many such specimens. Nickeliferous pyrrhotite is the principal nickel-bearing mineral, although olivine contains very minor amounts of nickel in solid solution, substituting for magnesium and iron. Such occurences are of no economic significance. Nickel analyses of possible economic significance (up to 3 pct Ni) have been returned from samples taken near the margins of the two large western dunite dikes. These samples were from schistose zones along and within the dike walls. The mineralized shear zones, up to 30 ft wide, strike N 30 W and dip from 65" to 90" west. They consist of layers of hard, fresh, green-gray dunite, mineralized with finely disseminated pyrrhotite. These layers alternate with layers of soft, black, oxidized schistose dunite up to 1 ft wide, well mineralized with pyrrhotite and tabular-fractured pentlandite in crystals up to 1/4-in. diam. Sulfides identified in polished sections were chiefly pyrrhotite and pentlandite, with much smaller amounts of chalcopyrite. There are two varieties of pyrrhotite. One develops a fine polish and conforms to published descriptions. The other is slightly darker and browner, does not polish as well, and displays flamelike growth or intergrowth structure when etched with nitric acid fumes. Pyrrhotite and pentlandite crystallized contemporaneously in the form of veins in the olivine and as fillings of the interstices of euhedral olivine crystals. Chalcopyrite replaces the other sulfides. The most striking feature of the deposits is their occurrence in intimately fractured and schistose zones in the dunite where faulting has been localized along the contacts of the sediments and the dunite dikes. Though far too little detailed work has been done to be certain, there appears to be a higher concentration of sulfides in the shear zones along the margins of dike apophyses, sediment reentrants, and strike and dip irregularities. Much more study would be required in order to submit a plausible theory of formation of the nickel deposits, supported by laboratory and field evidence. Results of the present study, especially localization of the metals by fracturing, certainly indicate that the nickel concentrations were brought about by precipitation of nickel sulfides from fluids that used the fractures as a means of ingress. Studies of nickel sulfide deposits throughout the world have demonstrated that such sulfides were deposited at considerable depths and at temperatures of several hundred degrees. This would rule out the possibility of groundwater as the transporting medium. The two possible sources of hot nickel-bearing fluids are quartz diorite and gabbro. The first possibility is that large volumes of fluids, expelled from the quartz diorite magma during its crystallization, obtained a supply of nickel by altering the nickeliferous olivine of the dunites. The likelihood of this process is lessened by the recognition that, although the dunites show some alteration to serpentine, talc, and trem-olite, they are for the most part remarkably fresh outside the schistose zones. The worldwide association of nickel with basic rocks, together with the presence of pyrrhotite in thin films on joint planes of the gabbro on Jumbro Mountain, favors the gabbro source. The writer extends thanks to C. Phillips Purdy, Jr., project chief of American Metal Climax Inc., for giving him the opportunity to study these deposits. He is also indebted to the officers of American Metal Climax Inc. and Discovery Mines Inc. for permission to publish this article.

Jan 1, 1961

By Wern-ping Chen, Jean Habimana, Jinyuan Liu, Mirza M. Rabbaig, Robert Barbour

To mitigate and control the combined sewer overflows from 17 outfalls in the City of Detroit, three outfalls in Dearborn Heights and eight outfalls in Redford Township, the Detroit Water and Sewerage Department has completed the preliminary design of a storage tunnel in 2005. In 2006, a final design has revised the alignments and the inside diameter (ID) of the tunnel. The revised tunnel system includes an 11.28-km(7-miles) 9.14-m (30-ft) ID tunnel, a 24.4-m (80-ft) ID pump station, two work shafts about 15.2-m (50-ft) ID each, and 14 drop shafts with various IDs. This paper discusses the latest development of this tunnel system.

Jan 1, 2007