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By Charles Will Wright

DESPITE the war, the First Pan American Mining Congress, held in Santiago, Chile, Jan. 15-23, was attended by about 300 persons including the official delegates from sixteen of the American republics. The United States delegation consisted of Elmer Pehrson, of the U. S. Bureau of Mines; D. F. Hewett, of the U. S. Geological Survey; William H. Hobbs, of the Carnegie Foundation; and C. W. Wright, delegate of the Board of Economic Warfare and of the A.I.M.E. Mr. Wright was elected to head the delegation. Among the other members were Edward Steidle, of Pennsylvania State College and also an official A.I.M.E. delegate; John Huttl, of Engineering and Mining Journal; W. 0. Vanderburg, foreign mineral specialist from Lima, Peru; O. B. Hundley, of the American Cyanamid Co.; Horace Graham, of the Anglo-Chilean Nitrate Co.; and several officials and engineers from the Anaconda, Kennecott, and Bethlehem Steel companies' mines in Chile.

Jan 1, 1942

By B. M. Larsen, T. E. Brower

INTRODUCTION AND SUMMARY BY "thermochemical factors" we refer to those variables which affect the net heat which must be put into the bath in order to make a heat of steel from any given set of charge materials. This is admittedly only one phase of the production rate problem. The whole problem includes also consideration of rate of charging, flame radiation intensity, rate of optimum fuel input obtainable without undue damage to the furnace structure and any variations in conditions such as stirring, slag volume or viscosity which affect the rate at which heat can flow down and away from those exposed surfaces where the heat is first received from the flame. Because a given type of charge in a shop is often considered as being nearly constant in both physical and chemical characteristics from one heat to another, and because such a state of affairs may be thought of as resulting in a reasonably constant net heat requirement, this requirement is usually neglected as an invariable, inevitable matter, about which nothing can be done. With normally variable charge, and variable percentages of limestone and cold pig, however, the net heat requirement can be subject to very appreciable change; it may also be affected by such things as the currently popular procedure of blowing oxygen into the bath, To bring the general problem of production rate into better perspective, therefore, it seems worthwhile to try to evaluate the net bath heat requirement and the amount by which it may change through variation in different factors. Because our calculated values of net heat are admittedly uncertain, we have tried to check them in part by statistical data on actual production rates over rather large groups of commercial heats. The results of calculation of net heat requirements in a wide range of actual commercial practices may first be summarized briefly. We find a wide range between the extremes of different practices, as would be expected, with duplex practice (essentially blown metal plus hot metal) having essentially a zero net heat requirement, an all-cold charge practice somewhat over 1 million Btu per ton of steel and a high hot metal practice about 0.75 million Btu per ton. Over the commercial range of scrap plus hot metal practice, increasing the percentage of hot metal from 40 to 78 pct, with other factors nearly constant, decreased the net heat by only some 5-10 pct, The net heat is increased by about 1.2 pct for each I pct of the metallic charge present as cold pig. Calculated values of oxygen supplied by air varied from about 25 up to 60 lb per ton of steel, and in a 60 pct hot metal practice, an increase from 32 to 52 lb oxygen from air decreased the calculated net heat from 0.88 to 0.74 million Btu per ton. Use of pure cold oxygen to substitute for about one half of the total charge ore (about 28 lb oxygen replacing 145 lb ore per ton of steel) decreased the

Jan 1, 1948

By Irwin R. Higgins

CONTENTS A. Introduction B. System Description C. Uranium Pilot Plant Programs D. Summary INTRODUCTION The Chem-Seps Continuous Countercurrent Ion Exchange (CCIX) contactor was first conceived of in 1951 at the Oak Ridge National Laboratory. In the 27 years that have passed, there has been a steady stream of pilot plant process development studies on a variety of processes far too numerous to mention. These have been in the area of water and waste treatment, chemical processing, ore leach treatment, and many others. Many successful production systems have been installed and operated in a variety of applications. A few of these are described herein together with a description of the system and its operational characteristics. SYSTEM DESCRIPTION Chem-Seps Continuous Countercurrent Ion Exchange* is a single loop in which various sections are separated by valves to isolate the sections performing different functions simultaneously. (Refer to Figure 1). To explain the working of a typical unit, let us use a simple configuration used in water softening or demineralization. The resin is moved in small increments by the hydraulic ram action. All solution flows are countercurrent to the flow of resin. The contaminants are removed in the process cycle and the resin is moved in the pulse cycle. A controller in the effluent stream from the treatment section senses the proper limit permissible in the effluent. In the process cycle, the influent enters through a set of distributors, moves downward and leaves through a set of collectors. Simultaneously the regenerant enters through valve RE and leaves through valve WA. The rinse enters through valve RI and its duration is controlled by an interface controller. In the process cycle, valves B, C, and D are closed, isolating all the sections. The duration of the process cycle is 4-10 minutes depending on the contaminants to be removed and is controlled either by a timer if the contaminants are fixed, or a controller in the effluent stream, if the contaminants fluctuate at short intervals. Valve A is open and resin is dropped to the pulse section simultaneously with the removal of contaminants in the treatment section, regeneration of loaded resin in the strip section, and rinsing of regenerated resin in the rinse section. As the resin drops through the valve A, it is backwashed to remove the suspended solids or resin fines. Removal of these fine particles is important to avoid the unnecessary pressure drop in the bed and plugging of the distributors. At the end of process cycle, all flows going into the unit and out of unit are automatically shut off. The valve A closes and valves B, C, and D open in proper sequence. A slug of water enters through valve PU, a predetermined incremental volume of resin moves into the regeneration section, an equal volume of regenerated and rinsed resin enters the bottom of the treatment section, and an equal volume of the loaded resin leaves the top of the treatment section and goes into the resin reservoir section. (The resin movement is plug flow with the Reynold's number being in the laminar region of the curve, and no fluidization occurs during the pulse cycle.) The total time required for proper sequencing of valves and the movement of resin is 20-30 seconds. At the end of this period, the valves B, C, and D close and valve A opens. The solution valves open and normal steady state operation begins. All valves are interlocked and properly sequenced. The resin movement is precisely controlled by sonic devices. Special Features of Chem-Seps CIIX "Downflow"*: The raw feed in the treatment section moves downward and the resin moves upward in the treatment section. The "downflow" of feed overcomes the handicap encountered in "upflow" systems. The "upflow" of feed requires a certain minimum flux during process cycle to lift the bed and keep it

Jan 1, 1979

By V. C. Wansbrough

A LUCID, thorough and powerful review of the impact of your tax laws on mining operations has already been presented by Granville S. Borden*. He has brought into focus and relief the pressure-points at which the shoe pinches most, has suggested some remedial measures, and enunciated much sound doctrine about the interrelationship and interplay of taxation policy and mining activity. Under the heading "What Every Lawmaker Should Know", he laid down the fundamental proposition that "the magnitude of our mineral resources varies inversely with the magnitude of the taxes levied upon them." With this, as with his other major premises, all mining men must be in hearty concurrence. There can be no doubt that a flourishing and expansive future for the mining industry in this country, in Canada, or anywhere else will depend on the thoroughness with .which these fundamental propositions are grasped by legislators, by national policy-makers and by public opinion at large.

Jan 1, 1950

By Oliver C. Ralston, Foster Fraas

Electrostatic methods of separation are used only when some peculiar advantage is gained. Such cases are minerals that are not separable by differences in specific gravity or magnetic response and that are desired in particles as large as 10-mesh, a size on which flotation separation is inefficient. This paper covers several separations of this type and others. It includes studies in the electrostatic behavior of kyanite, sillimanite, and zircon, simple silicates that cannot be called either acid or basic but are more nearly neutral. Kyanite and sillimanite are both desired in 10-mesh size and are difficult to bene-ficiate from low-grade ores to give that type of concentrate. A separation of garnet from diopside was studied because this mixture had been removed from a wollas-tonite product by drying and magnetic separation, and no special or extra-preparation for electrostatic separation was necessary. The Separator The separator used in these tests is of the nonhomogeneous field type shown in Fig Ia. It consists of a 11.4-cm-diam rotating metal roll 2 at ground potential over which the dry mixture of minerals is fed. The roll serves as one electrode of the separating field, and the other electrode is that of 3, a smaller 5-cm-diam rotating metal cylinder which is held at a high direct-current potential. In this paper the term "electrode" will be confined to the electrode at 3, roll 2 being designated only as "roll."

Jan 1, 1949

By H. J. Struth

A glance into the immediate future of the refining industry, and a retrospective view of 1929, cannot fail to emphasize the need for effective measures of control of refinery still runs. With oil producers alert to the need for control of the crude supply, it has become more than ever necessary for refiners to complete the movement toward stabilization by concerted determination to maintain still run schedules within the limitations prescribed by the demand for gasoline. The outlook for continued growth in the demand for gasoline appears to be well sustained by a preliminary survey of requirements for 1930. In fact, it is apparent that the industry will be assured of a market for gasoline that will aggregate in volume at least 472,000,000 bbl. this year. This indicates a gain in total demand over 1929 of about 9 per cent. or about 4.6 per cent, less than the gain recorded during 1929 over 1928, which amounted to 13.6 per cent. Despite the indicated increase in gasoline demand this year, it is apparent that little, if any, more crude will be required than last year. This is shown in Table 1, presenting estimates of gasoline demand and probable crude requirements for 1930. Table 1.—Preliminary Survey of 1930 Gasoline and Crude Run Requirements Millions of Barrels Doniestic gasoline demand................................... 397 Foreign gasoline demand..................................... 75 Total indicated demand...................................... 472 Natural gasoline content..................................... 53 Net gasoline from crude...................................... 419 Imported gasoline........................................... 13 Net gasoline required from refineries.......................... 406 Indicated excess stock Dec. 31, 1929........................... 10 Maximum protluction required................................ 396" At 40 per cent. gasolitlc recovery, this represents a maximum crude converson of 990,000,000 bbl., or a daily average for the ycar 2,712,000 barrels. Year after year, the refining branch of the petroleum industry has been found guilty of running crude to stills greatly in excess of normal requirements, causing frequent periods of market depression. A review

Jan 1, 1930

By Charles F. Ramseyer

The manufacture of iron and steel is one of the largest of our industries; and in point of size of single plant and equipment certainly the biggest of all industries. By the general public it is generally considered a prime example both of the marvelous technical advances achieved by modern science and engineering in the design and operation of equipment and of the efficiency of big business in the coordination of men and materials. Actually the operation of its basic processes has not changed significantly in either theory or fundamental design of equipment in the past 75 years. Though many other process industries have been born and developed, and not seldom completely revolutionized, during this period, the primary processes of making iron and steel are still carried out along the lines laid down, and in the equipment originated so long ago, by Bessemer, Siemens and Martin, and subsequently expanded to practically the modern scale by Carnegie, Schwab and Captain Bill Jones in the eighteen eighties and nineties. The application of the principles underlying the continuous counter-current physical and chemical interaction of solids, liquids and gases, which have been so successfully used in the rapid evolution of our chemical process industries, has been very largely lacking in the steel industry. In the days of the last-named giants, especially Carnegie, the steel industry made great and rapid technical progress. Carnegie's ever driving idea (as later with Ford in the production of automobiles) was the finding of new and better ways of making cheaper steel. Carnegie himself was a steelman, and so long as he dominated the industry its technical progress was rapid; and he, like Ford, was vastly successful financially as well, since his costs were continually being driven lower than those of his competitors by his advances in steelmaking technique.

Jan 1, 1935

By Charles F. Ramseyer

The manufacture of iron and steel is one of the largest of our industries; and in point of size of single plant and equipment certainly the biggest of all industries. By the general public it is generally considered a prime example both of the marvelous technical advances achieved by modern science and engineering in the design and operation of equipment and of the efficiency of big business in the coordination of men and materials. Actually the operation of its basic processes has not changed significantly in either theory or fundamental design of equipment in the past 75 years. Though many other process industries have been born and developed, and not seldom completely revolutionized, during this period, the primary processes of making iron and steel are still carried out along the lines laid down, and in the equipment originated so long ago, by Bessemer, Siemens and Martin, and subsequently expanded to practically the modern scale by Carnegie, Schwab and Captain Bill Jones in the eighteen eighties and nineties. The application of the principles underlying the continuous counter-current physical and chemical interaction of solids, liquids and gases, which have been so successfully used in the rapid evolution of our chemical process industries, has been very largely lacking in the steel industry. In the days of the last-named giants, especially Carnegie, the steel industry made great and rapid technical progress. Carnegie's ever driving idea (as later with Ford in the production of automobiles) was the finding of new and better ways of making cheaper steel. Carnegie himself was a steelman, and so long as he dominated the industry its technical progress was rapid; and he, like Ford, was vastly successful financially as well, since his costs were continually being driven lower than those of his competitors by his advances in steelmaking technique.

Jan 1, 1935

By John Wulff, J. H. Hollomon

Service failures in brass condenser tubes are often due to corrosion. One of the commonest types of corrosion reveals a surface structure of redeposited copper.' The study of the effect of alloy addition agents in preventing this kind of corrosion has received impetus from the extensive publication of Bengough and May.2 The mechanism of such inhibition gauged from immersion corrosion,2 cell corrosion,3 and electrolytic potential4 measurements is controversial. This controversy may be attributed in part to a lack of definite knowledge5 of the actual nature of the initial films formed in corrosion experiments. In our own corrosion work on copper and 70-30 brass this lack became apparent and necessitated an examination of surface films by X-ray and electron diffraction methods. The present paper is but an introduction to the subject of inhibition and reports the structure of films formed in active corrodents. Experimental Procedure The arsenical coppers and brasses used in this investigation were made by one of the writers* in the plant of the Revere Copper and Brass Co. at Rome, N. Y. Standard commercial melting practice was followed. O.F.H.C. copper and electrolytic zinc were used and all arsenic additions were made by additions of a master copper alloy. The final analyses are given in Table I. Likewise, the extrusion, cold-rolling, and intermediate anneals employed followed standard usage. Final heat-treatments were given to all materials to produce a similar grain size (0.035 to 0.045 mm. for brass and 0.015 to 0.025 for copper) for the alloys containing various percentages of arsenic. Samples 1/2 by M by 1/4 in. were cut from sheet material resurfaced and finished with 0000 metal-lographic papers. The surfaces were all degreased in alcohol and benzine before immersion. After immersion in the corrodent, they were washed gently in tap water, dipped first in alcohol and then in pure benzine and allowed to dry in the diffraction apparatus. The reflection electron diffraction apparatus used has been described by Burwell and Wu1ff.6 Fig. I is typical of the photo-grams obtained. The X-ray apparatus was

Jan 1, 1941

By H. J. Struth

In these trying times of proration and low oil prices, it is decidedly necessary for all branches of the petroleum industry to accord full recognition to the economic phenomena that contribute to its varying state of welfare. Perhaps no other single factor has a more important bearing upon the general oil situation than the supply and demand of gasoline. Year after year, the records have shown that the degree of prosperity or depression accompanying the industry's developments has been to a large extent influenced by the degree of balance maintamed between the supply and demand of gasoline. More and more it is being realized within the industry that equilibrium between the supply and demand of gasoline forms the basic structure of crude and product market values and, consequently, the deciding factor in the financial results of the industry as a whole. The influence of the gasoline situation upon the market and financial structure of the petroleum industry was effectively demonstrated during 1930, when excess accumulation of gasoline undermined not only the refined oil market but the crude market as well. In fact, it was a top-heavy gasoline situation that defeated the realization of benefits that might have accrued from an otherwise favorable statistical position in the producing branch of the industry. Indicative of this is the fact that crude oil production was curtailed to the extent of 98,323,000 bbl. last year, while refinery runs to stills were maintained at an excessive rate until late in the year, creating an excess gasoline production of 6,663,000 bbl. above actual requirements. Nevertheless, the movement to curtail refinery operations during the closing months of the year prevented a far worse situation, although it came too late to turn the ebbing momentum of the general oil market. Despite the severe depression of the market values that accompanied 1930 developments, it can be said that the results attained during the closing months of the year, in the direction of production control, marked a decisive turn in the industry's economic affairs. In fact, a review of the oil situation from every angle points definitely to a better general understanding and recognition of the workings of the economic law of supply and demand. As a result, the year closed with crude production in

Jan 1, 1931

By R. E. H. Pomeroy

The statistical data given in this paper are taken from the actual performance of the No. 2 reverberatory furnace of the Nevada Consolidated Copper Co., Mc Gill, Nev., for a period of four months, from April to July, 1914. The principal furnace dimensions are: Length, 132 ft. % in. at the skim-line level; average width, 18 ft., 10 in. at the skim-line level. The roof is 7 ft. above the skim-line level at the firing end. The average area in the uptake flue is 36 sq. ft., and the area above the skim line under the vulcatory arch is 24.3 sq. ft. Fig. 1 shows a diagrammatic plan and sectional elevation of this furnace. The furnace is equipped with two 400-b.h.p. Stirling waste-heat boilers set in parallel. California crude petroleum is used for fuel and has a specific gravity of 16.5" B., flashing in open test at 199" F. The oil is heated to about 200" F. in a steam heater before going to the burners, requiring about 9 b.h.p. per furnace day to heat it from the line temperature to the burning temperature. Measurement is made by oil meter, checked daily by reservoir readings. The oil is fed by gravity (34 Ib. static pressure) to seven low-pressure blast burners of the Steptoe type (Fig. 2). The blast for these burners is supplied at about 40-08. pressure by a motor-driven Connersville blower of 42 cu. ft. capacity per revolution. The air supplied by the blower through the burners for atomizing the oil amounts to about 10 per cent. of the theoretical air necessary for complete combustion of the oil. The remainder of the necessary air enters the furnace through the burner openings in the firing wall. No checker holes are provided, and the charge holes in the roof are equipped with slide gates and " dog houses" to minimize air leakages. The combustion of the fuel, as shown by gas analysis at the front of the furnace, is practically complete, the carbon monoxide in the gases being less than 0.5 per cent. The draft at the firing end of the furnace is 0.18 in. of water. At the throat or in the uptake above the "verb" the draft is about 1 in.

Jan 1, 1915

By William Hilliard

IN any manufacturing business, it is of vital importance that the management should know the exact cost of the units of production. Without such knowledge, a company can sell blindly in the open market, obtaining the best prices it can in competition with other firms, and manage perhaps to continue in business for a time; but at any moment, and especially in a period of falling prices, such a firm is at a loss to know exactly at what point it can sell at a profit and exactly how much it is losing per unit if it sells below that point. Furthermore, it is necessary not simply to know the exact total cost per unit, but to know definitely all the different-factors which enter into that cost. A firm manufacturing pocket knives had been doing a profitable business for many years when it began to earn smaller and smaller profits, until there was scarcely any profit at all being realized. Being unable to determine exactly what its future policy should be, it called in experts who studied the past records carefully and followed out for a period a better cost, system. Investigation then showed that on several different kinds of knives in common use, a small profit per unit was being made. On a number of special kinds of knives, of which the firm was very proud, it had been forced to cut prices under the pressure of outside competition and had believed that a small profit per unit was still being made on that product, while a detailed cost analysis showed that a loss was being incurred on each knife of that kind produced. It then became clear that the company must either give up the special line and concentrate wholly on the cheaper knives and extend their sales to territory not yet developed; or expand its plant and produce more of the higher grade knives and thus lower the cost per unit enough to make money on the higher grade knives also, if conditions warranted such expansion. Investigation revealed that the market for large quantities of the high-grade -knives was decidedly uncertain and that the most promising move would be to manufacture only the less expensive knives on a larger scale. That plan was carried out and the concern began again to make a better profit.

Jan 1, 1932

By John Wulff, J. H. Hollomon

Service failures in brass condenser tubes are often due to corrosion. One of the commonest types of corrosion reveals a surface structure of redeposited copper.' The study of the effect of alloy addition agents in preventing this kind of corrosion has received impetus from the extensive publication of Bengough and May.2 The mechanism of such inhibition gauged from immersion corrosion,2 cell corrosion,3 and electrolytic potential4 measurements is controversial. This controversy may be attributed in part to a lack of definite knowledge5 of the actual nature of the initial films formed in corrosion experiments. In our own corrosion work on copper and 70-30 brass this lack became apparent and necessitated an examination of surface films by X-ray and electron diffraction methods. The present paper is but an introduction to the subject of inhibition and reports the structure of films formed in active corrodents. Experimental Procedure The arsenical coppers and brasses used in this investigation were made by one of the writers* in the plant of the Revere Copper and Brass Co. at Rome, N. Y. Standard commercial melting practice was followed. O.F.H.C. copper and electrolytic zinc were used and all arsenic additions were made by additions of a master copper alloy. The final analyses are given in Table I. Likewise, the extrusion, cold-rolling, and intermediate anneals employed followed standard usage. Final heat-treatments were given to all materials to produce a similar grain size (0.035 to 0.045 mm. for brass and 0.015 to 0.025 for copper) for the alloys containing various percentages of arsenic. Samples 1/2 by M by 1/4 in. were cut from sheet material resurfaced and finished with 0000 metal-lographic papers. The surfaces were all degreased in alcohol and benzine before immersion. After immersion in the corrodent, they were washed gently in tap water, dipped first in alcohol and then in pure benzine and allowed to dry in the diffraction apparatus. The reflection electron diffraction apparatus used has been described by Burwell and Wu1ff.6 Fig. I is typical of the photo-grams obtained. The X-ray apparatus was

Jan 1, 1941

Jan 1, 1971

By Charles M. Rolker

It is not my purpose to present a complete description, still less a thorough discussion from a theoretical stand-point, of the Leadville ore-deposits. Hence I have given to this paper the more modest name of " Notes;" since it is little more than a record of observations made three or four years ago, and now published from my original memoranda, with the view of preserving the facts rather than of

Jan 1, 1886

By V. F. Parry, S. P. Burke

The presence of gas in coal mines necessitates the use of costly ventilation arrangements and the use of expensive mining methods. On the other hand, the gas itself in many instances is of considerable intrinsic value, and its separate recovery might conceivably be a profitable undertaking. This paper is concerned with a study of the movement of gas in coal strata with the object of determining the laws governing gas movement and thus making at least a preliminary step toward the solution of the more practical problem of its control or recovery. Naturally, so important a subject has received much attention from scientists and engineers. In most cases, however, the studies have been concerned with the origin1$, the amount" the composition3 and the method of retention4 of the gas in coal; or, from the more practical side, have been concerned with the phenonlena and conditions associated with outbursts5 or explosions and their control. Numerous studies also have been made of the permeability of coal to gas" of gas pressures measured in coal seams, etc. The authors are unaware, however, of any attempt to present a consistent or complete picture of the laws governing the movement of gas through the coal. Study in West Virginia A recent study conducted at this University7 gives the first presentation of the distribution of pressures in a small section of a coal seam. Holes were drilled into the coal rib to various depths and at various distances from the coal face. The location selected for study was as remote as possible from disturbing influences of mining operations, faults, "wants," etc. The pipes extending into the coal that were used to determine pressures were grouted into the borehole for the entire depth of the hole, and great precaution was taken to insure accurate pressure readings. A map of the geology of the region, a map of the probable boundary and extent of the coal seam, a current map of the mine and a

Jan 1, 1936

By W. M. Bertholf

In 1945 tests were made in the coal washery of the Colorado Fuel and Iron Corporation, at Pueblo, Colo., to determine the value of the Humphreys spiral. So far we have demonstrated that it is of definite value to us in rewashing a portion of our table middlings; and we are fairly certain that this is not necessarily the only place in which it can be used to advantage. Because of manpower and material shortages, experimental work has been discontinued for the present. Three of the spirals are being installed for use in rewashing the middlings, and testing and experimental work will proceed when this installation is completed. All evidence secured so far points to the fact that the spiral call make an effective separation of heavy material below 8-mesh; but that it is ineffective in removing larger, heavy material. This, of course, will limit its use to fine coal or a classified feed containing no heavy material larger than 8-mesh. In considering the results of our tests, it should be noted that the feed was our table middling, and that any real separation of this material is a "moral victory)" as there is little material that could be properly called coal and practically no heavy rock, the consequence being that previous attempts to clean the middlings have not been at all successful. Several articles dealing with the spiral and its use in treating heavy minerals have already been published,' but for the benefit of those who have not seen these we include a brief description of the spiral and of the way it operates, taken from Bulletin 4 of The Humphreys Investment Co.: The Humphreys Spiral Concentrator consists of a spiral conduit of modified semicircular cross section. Ore pulp is fed to the top and, as it flows downward, the heavier particles concentrate in a band along the inner side of the pulp stream (Fig. I). Outlets for removal of products are located at the lowest points in the cross section of the conduit. Wash water, added at the inner edge of the stream, flows outwardly across the concentrate band. The width of concentrate band removed at the outlets is controlled by adjustable splitters. Concentrate is usually removed from the upper portion of the spiral and middling from the lower portion. Tailing is discharged from the lower end. Tests are usually made in closed circuit, since this provides a maximum of information with a minimum amount of sample. Fig. 2 shows the spiral set up for closed-circuit testing, and gives a good idea of the general arrangement of such an installation. The small cyclone separator is used to provide clean wash water without introducing additional water into the circuit.

Jan 1, 1947

By W. M. Bertholf

In 1945 tests were made in the coal washery of the Colorado Fuel and Iron Corporation, at Pueblo, Colo., to determine the value of the Humphreys spiral. So far we have demonstrated that it is of definite value to us in rewashing a portion of our table middlings; and we are fairly certain that this is not necessarily the only place in which it can be used to advantage. Because of manpower and material shortages, experimental work has been discontinued for the present. Three of the spirals are being installed for use in rewashing the middlings, and testing and experimental work will proceed when this installation is completed. All evidence secured so far points to the fact that the spiral call make an effective separation of heavy material below 8-mesh; but that it is ineffective in removing larger, heavy material. This, of course, will limit its use to fine coal or a classified feed containing no heavy material larger than 8-mesh. In considering the results of our tests, it should be noted that the feed was our table middling, and that any real separation of this material is a "moral victory)" as there is little material that could be properly called coal and practically no heavy rock, the consequence being that previous attempts to clean the middlings have not been at all successful. Several articles dealing with the spiral and its use in treating heavy minerals have already been published,' but for the benefit of those who have not seen these we include a brief description of the spiral and of the way it operates, taken from Bulletin 4 of The Humphreys Investment Co.: The Humphreys Spiral Concentrator consists of a spiral conduit of modified semicircular cross section. Ore pulp is fed to the top and, as it flows downward, the heavier particles concentrate in a band along the inner side of the pulp stream (Fig. I). Outlets for removal of products are located at the lowest points in the cross section of the conduit. Wash water, added at the inner edge of the stream, flows outwardly across the concentrate band. The width of concentrate band removed at the outlets is controlled by adjustable splitters. Concentrate is usually removed from the upper portion of the spiral and middling from the lower portion. Tailing is discharged from the lower end. Tests are usually made in closed circuit, since this provides a maximum of information with a minimum amount of sample. Fig. 2 shows the spiral set up for closed-circuit testing, and gives a good idea of the general arrangement of such an installation. The small cyclone separator is used to provide clean wash water without introducing additional water into the circuit.

Jan 1, 1947

By John C. Cook

Long-wave short-pulse radar has been shown capable of exploring to distances of several hundred feet through massive, dry rock salt. Exploration distances of 30 to 60 ft through bituminous coal and massive limestone, respectively, have also been demonstrated with low-power experimental radar equipment in underground mines. Working ranges up to 250 ft in limestone and coal are considered feasible. Radar reflections should be produced by all large electrically contrasting objects such as fault gouge masses, wet shattered ground, metallic mineralization, adjacent mine workings (dry or flooded), and abandoned drill holes. It is believed that radar can locate such obstacles in advance of underground mining through all massive rocks of low free-water content, including many igneous and metamorphic rocks. Three years of studies and experiments in radar exploration through rocks are reported.

Jan 1, 1974

By V. F. Parry, S. P. Burke

The presence of gas in coal mines necessitates the use of costly ventilation arrangements and the use of expensive mining methods. On the other hand, the gas itself in many instances is of considerable intrinsic value, and its separate recovery might conceivably be a profitable undertaking. This paper is concerned with a study of the movement of gas in coal strata with the object of determining the laws governing gas movement and thus making at least a preliminary step toward the solution of the more practical problem of its control or recovery. Naturally, so important a subject has received much attention from scientists and engineers. In most cases, however, the studies have been concerned with the origin1$, the amount" the composition3 and the method of retention4 of the gas in coal; or, from the more practical side, have been concerned with the phenonlena and conditions associated with outbursts5 or explosions and their control. Numerous studies also have been made of the permeability of coal to gas" of gas pressures measured in coal seams, etc. The authors are unaware, however, of any attempt to present a consistent or complete picture of the laws governing the movement of gas through the coal. Study in West Virginia A recent study conducted at this University7 gives the first presentation of the distribution of pressures in a small section of a coal seam. Holes were drilled into the coal rib to various depths and at various distances from the coal face. The location selected for study was as remote as possible from disturbing influences of mining operations, faults, "wants," etc. The pipes extending into the coal that were used to determine pressures were grouted into the borehole for the entire depth of the hole, and great precaution was taken to insure accurate pressure readings. A map of the geology of the region, a map of the probable boundary and extent of the coal seam, a current map of the mine and a

Jan 1, 1936