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By R. H. Lee

Without doubt, one of the most frequent and serious ani~oyailces connected with the practical running of a blast-furnace, especially in single-furnace plants, is caused by low steam, in spite of the fact that all boilers at blast-furnaces have grates for burning coal, and that coal is more or less continuously burned upon them, from three to a dozen men being pretty constantly engaged around the boilers as firemen or coal- and ash-handlers. At times, when the furnace is " tight," all available men arc put on to assist the regular firemen; yet sufficient steam cannot be got to keep the engines up to their regular number of revolutions, while the stoves, deprived of the gas which has been sent to the boilers, run cold, so that, when the furnace loosens up and resumes the regular rate of driving, the blast is very considerably below normal temperature, and a "cold," or at best a " high-sulphnr," cast is the result. Again, it often happens that a furnace, running at its best, becomes temporarily a little too hot: the pressure rises; the amount of gas made is diminished; the steam soon commences to go down; and a small scaffold is likely to form before the furnace has been brought back to the proper rate of driving, and thus enabled to take its regular amount of blast. The usual remedy is either to "jerk" the furnace by a sudden, brief intermission in blowing, or to cool the furnace by lowering the heat of the blast; but if the lower blast-temperature be maintained too long, the hearth and descending stock may be cooled below the " critical temperature" mentioned by Mr. Johnson,' and the furnace may go to the other extreme, and become cold. This is especially the case when coal or coke high in sulphur is used.

Jan 1, 1907

E. A. HOLBROOK,*Urbana, Ill.-To those who have followed the development of powdered coal two questions often occur. First, as to the moisture in the coal. In Illinois we recognize that the bituminous coals contain about 12 to 15 per cent. of what we call "contained moisture," that is, the moisture is present in the coal although this may appear absolutely dry and dusty. In addition, the surface moisture may be present in any amount. I would like to ask what is the relative effect of these two forms of moisture upon the work of pulverizing. Does Mr. Collins refer to the contained moisture or to the surface moisture in estimating the degree to which the coal must be dried? H. R. COLLINS.-In the lignite coals, of which this country possesses a great deal and is beginning to develop them to considerable extent, the "contained" or "combined" moisture does not .trouble us; we have no difficulty in reducing lignites to a high degree of fineness. But when dealing with bituminous, sub-bituminous, or semi-bituminous, we, prefer to reduce the combined moisture as well as the hydroscopic moisture as far as possible. We have recently put into operation, at a plant, furnaces and boilers consuming the lignite from northern New Mexico, which contains between 4 and 5 per cent. moisture as we pulverize and burn it. The evaporating efficiencies under the boilers have been so remarkable that we wish to check the results half a dozen times before quoting them. We have also just started two boilers at the Garfield smelter, and have obtained the same high efficiencies.

Jan 11, 1918

By Joseph Kuti

ROOF SUPPORT DEVELOPMENTS IN LONGWALL (1) European longwall mining technology developed towards its modern form in relatively deep mines. With increasing depth the stability of openings driven for ventilation, travel or transport becomes paramount in mine design considerations. As a result the number of roadways and entries, as well as their width must be a minimum. (1) Another important aspect of European mining is the high density of mineable seams, as opposed to the wide lateral extension of a single seam in the U. S. A. Multi-seam mining requires strict planning and near 100% extraction, since with increasing depth, the effect of remnant pillars can be devastating. As a result the face layout of a modern European longwall panel is based on single panel entries of moderate width and great height. The mode of extraction is generally a mixture of the advance and retreat system which is called a 2-system. It is obvious, therefore, that the supports developed for the entries and for the intersection areas are more complex than those in the U. S. A.

Jan 1, 1981

By Blamey Stevens

My previous paper is entitled, The Laws of Igneous Ernanation Pressure. The present paper lays no claim to the exactitude and completeness of a law, since it is of a provisional nature and may be disregarded when experiments have established a basis for more exact reasoning. The general physical states in which aqueous emanations may occur are first considered. The possible physical couditions under which the mineral elements may occur in emanations are then discussed, and a classification of deposits, dependent on emanation, is proposed. A system of scientific experimental investigation is outlined, and it is shown that the physical and chemical properties of emanation may be exactly determined thereby. The investigation is urged as feasible and simple, and not necessarily requiring large and costly apparatus. It is the only step necessary to make possible the formulation of a complete set of laws of igneous emanation. Process of Emanation. In a rising column, magma ranges in temperature from 900° to 1,200°C. Exhalation must begin at some fairly great depth. What this depth may be we can only surmise, since no experimental evidence is available. Exhalation, however, continues as the magma flows upward, until at another level the occluded gases have all escaped. This depth is probably upward of 5,000 ft. (See Fig. 1.) All exhalations must come from between these two levels. As the whole emanation is the sum of the exhalations and residues, the residues must come from below the uppermost level. They will be most abundant when coming from those parts of the intrusion which have solidified below the lower level.

Jan 1, 1913

By G. S. Morison

I have bad considerable experience with the testing-machine at the Watertown Arsenal, having had broken there sixteen large steel eye-bars, besides quite a number of iron bars and two compression members. So far as accurate mid satisfactory results are concerned, the machine is all we could ask for, and the officers who have it in charge, together with their civil assistants, are thoroughly conversant with it 1 details, and entirely competent to make the tests required. The principal defect is that the force is very inadequate. As the machine is arranged, tile weighing apparatus is at one end and stationary, the measure of strain being carried from this to the scale-beam by the fluid in a tube m small that it looks like a wire. At the other end is placed the hydraulic press by which the power is applied; this press is mounted on a small carriage and held by two eight-inch screws about four feet above the floor, which arc of course strained in compression during tensile tests, and in tension during' compression tests. When the stretch of the material has exhausted the throw of the plunger it is necessary to relieve the strain, draw back the plunger, and move the carriage along, which is done by nuts turned by steam working on the large screws. Every specimen placed in the machine must be lifted above the large screws and lowered into position. To do this, crabs, running on travellers, which span the entire room, are placed over the machine, and by these the specimen can be lifted and put in place. The actual time required to make a test depends largely on the amount which the material stretches, bat it may generally be said, that for specimens which will stretch from two to three feet the

Jan 1, 1882

THE turn of the century was marked by the appearance of a series of greatly important pieces of research that became the foundations of modern physical metallurgy. It is, of course, some- what misleading to ascribe the growth of a science, or a branch of engineering, to the work of a few men, as it is to write history generally in terms of great men, for this approach neglects back- ground development, and tends to overemphasize the importance of immediately subsequent events; the correlative and steady growth of the basic sciences added to the resources of the new science of metals--developments in basic science .years later were to appear in their application to metal systems. Yet it is useful to emphasize the importance of these relatively few pieces of research. THE PHASE RULE The work of Willard Gibbs on heterogeneous equilibria, which included the derivation of the phase rule, was published obscurely in the journal of the Connecticut Academy.30 Unearthed by the German physical chemists (evidently by van der Waals, to use Ostwald's phrase, "aus dem staubigen Fundort"), its importance to the study of alloys was pointed out by Jüptner31 and by Le Chatelier; its application to polycomponent systems, and to metal systems in particular, was developed by Rijn van Alkemade (1893), by Le Chatelier;8a and especially by Roozeboom (1899-1900). The work of Raoult on the depression of the freezing point by solutes led to the study of the phenomenon in amalgams and shortly to metal systems. Work was done, by Roberts-Austen and others, on the initial freezing temperatures of binary alloys-the liquidi, data applicable to Raoult's work. Van't Hoff in 1890 had pointed out

Jan 1, 1948

By H. Rush Spedden

R. T. Hukki has extended his study of ball mill grinding at supercritical speeds with an excellent mathematical analysis of tumbling mill grinding. When he speaks of supercritical speeds he is referring to the original Fahrenwald critical-speed formula. He said that, as an example of the use of supercritical speeds, if a fine grinding mill of any type is wet-grinding ore of 3.5 sp gr with steel balls at a certain conventional subcritical speed, the same power input and capacity should be obtainable with autogenous medium of 3.5 sp gr at a speed 100 to 120 pct of the critical in a grate- type mill of the same effective size. In addition, he introduced what he calls the base mill concept which, he stated, makes it possible to compare performances of mills of different sizes grinding with a metallic medium or with an autogenous medium of any specific gravity and at any speed. He showed the use of this concept and explained how it makes possible the evaluation of mill sizes and motors for any grinding purpose at any accuracy well within the conventional standards of design in milling practice. He further stated that the maximum capacity in pilot plant mills with various media, either metallic or autogenous, has always been found to be within the supercritical speed range. In his discussion of this paper he substantiated these findings with statements showing the increased capacity obtained in a milling plant in Finland which followed his principles.

Jan 7, 1960

By Basil Prescott

A thorough knowledge of the peculiarities of this type of orebody is necessary in sampling these limestone replacement deposits. Oxidized ores are often overestimated because of error in determining specific gravity and actual cross-section of the orebody, and sulfide ores are often underestimated because it is difficult to scatter the samples so that they will accurately represent the area under consideration. This paper describes various methods of sampling and cites factors that enter into the estimation of these deposits. IN THE science of evolution of the species, there is a law which, simply stated, avers that the history of the individual repeats the history of the race. Similarly, if unassisted by the experience of others, each successful engineer would perfect and develop his methods and technique from the rough grab sample up to the carefully taken, recorded and studied samples and observations which now determine and decide the expenditure of the large sums required for modern mining. Hence real progress results from the interchange of experience, as in that way the entire experience of the profession can be made available to every engineer. The literature of this subject is already voluminous, but some progress has been made in the gathering of data and in their compilation or presentation.

Jan 3, 1924

By John M. Hird

Control of artesian ground water has played an important role in the development of Texas Gulf Sulphur's phosphate mining venture in eastern North Carolina. To facilitate dry mining methods, 60 million gpd of fresh water is pumped through wells from a limestone aquifer underlying the uniform flat-lying ore section. Hydrologic information revealed from pumping tests has been used in successfully developing a depressurizing system. Computer assistance is used to plan well patterns. High volume pumping has lowered water levels in water wells over a large area in the Coastal Plain without detrimental effects on water quality in the aquifer. Cooperative effort between mining firms will be required to control the ground water as new mines are developed in the district. An intricate observation -well system is monitored regularly over the wide area of pumping effect to ensure that gradient reversals have not caused salt water encroachment.

Jan 1, 1972

By P. Somasundaran

INTRODUCTION Large amounts of mineral values are discarded today as fines and ultrafines, because of inadequate technology to process them economically. Most conventional mineral processing techniques fail in the sub-sieve range. Fines respond poorly to processes such as flotation either due to change in mineralogy and surface composition or even simply due to the direct effect of their smallness in size on collision and adhesion rates between them and air bubbles. Indeed if the poor flotation is due to the smallness in size, a solution must rest in aggregating the fines. Inorganic electrolytes as well as polymers have been successfully used as flocculants in the past for obtaining increased flotation of colloidal material from waste water effluents. In mineral beneficiation, this technique can be profitably used if the process of flocculation can be made to take place selectively. The power of the selective flocculation technique has already been proven, with the successful application of it in the case of beneficiation of low grade iron ore by the Cleveland-Cliffs Iron Ore Company and potash ore by Cominco. The process holds tremendous potential when it is followed by flotation, elutriation, etc. Today its application is, however, limited to the above two cases and it has become clear that a full understanding of the process will prove helpful for developing solutions to various problems that exist both at the basic and applied levels. In this paper, principles that are known to govern selective aggregation processes such as selective flocculation, carrier flotation and spherical agglomeration will be examined and areas of uncertainties will be identified.

Jan 1, 1979

By J. A. Eisele

The Bureau of Mines has played an important role in the revival of precious-metal mining underway in the Western United States. During the past 30 years, many techniques used by industry to recover gold and silver were pioneered and developed by the Bureau of Mines. In 1952, technology was developed to strip gold from granular activated carbon and allow the carbon to be reused. In 1969, the heap leaching concept was applied to low-grade gold and silver ores and mine wastes. Heap leaching in conjunction with carbon adsorption-desorption permits very low value material to be economically processed. In 1970, an oxidation treatment based on hypochlorite was developed to increase the recovery of gold from carbonaceous gold ores by cyanidation. In the early 19501s, attempts were made to employ carbon-in-pulp technology to recover gold from ores, but the fixed price of gold and increasing operational costs made the process unprofitable. The Bureau of Mines and Homestake Mining Co. jointly operated a carbon-in-pulp pilot plant, and the technology was used in full-scale production at the Homestake Mine in 1972. In 1973, a pressure stripping method, which decreased the time needed for the stripping step, was developed to desorb gold and silver from carbon. An alcohol desorption method, developed in 1976, also decreased the carbon stripping time. These stripping methods are in commercial use. In 1979, an agglomeration pretreatment was developed that permitted clayey precious metal ores to be heap-leached. Agglomeration-heap leaching technology is being used by at least 30 operations, several of them major gold and silver mines. Almost all precious-metal-mining companies use at least one of the above techniques in production facilities.

Jan 1, 1984

By Peter G. Groer

Several methods1-3 are being used to determine the WL and individual Rn-daughter concentrations in uranium mine atmospheres. The best of these methods is the one given in Ref. 3. According to this method, the WL and the Rn-daughter concentrations are determined from the total a-counts observed during three consecutive time intervals. Its only disadvantage lies in the fact that rather involved calculations are necessary to convert the observed counts into WL or pCi/l (picocuries per liter). There are, however, counting intervals that give simple weighting coefficients for the observed counts. This fact makes it possible to convert from a-counts to WL or pCi/l with the aid of a graph. After some trial runs on a computer the following equations emerged as the basis for the most practical procedure: [ ] NA, N.., and & stand for the number of RaA, RaB, and RaC atoms per liter of air. C(t1,t2) denotes the counts observed from time t. to time t2 (in minutes) after the end of the 5-min sampling period. E is the detector efficiency and V is the flow rate in liters per minute. With an accuracy loss of less than -5% one finds from [Eq. 1] by adding the corresponding terms: If the WL would have been calculated according to [Eq. 2] instead of using the graph, the result would have been 0.31. Since the values used for C's under [Eq. 3] represent the exact number of counts from a Rn-daughter mixture in equilibrium with 100/3 pCi of Rn the exact WL of this mixture can be calculated easily. The exact value is: [ ] This shows that the method is quite accurate for the 0.3 WL domain. The precision of the method excluding errors made in reading the graph can be estimated with the help of the following formula: [ ]

Jan 1, 1974

By Chase Palmer

INTRODUCTION. WHILE the reducing action of organic matter, of ferrous sulphate, and of hydrogen sulphide has frequently been invoked to account for the deposition of native gold and silver from ore-forming solutions, the high efficiency in this respect of certain of the metallic minerals which form the ore itself has not been sufficiently recognized. If a little finely powdered chalcocite is placed. in a test-tube and 2 or 3 cc. of a dilute solution of gold chloride are poured over it, two or three shakes of the tube suffice to remove all the gold from the solution. The color of the solution changes from yellow to pale green, showing that copper is dissolved simultaneously with the precipitation of metallic gold. If a piece of chalcocite is hung in a dilute aqueous solution of silver sulphate (1 normal), a coating of silver begins immediately to form on the mineral, and within a few moments a beautiful silver tree has developed, similar to that formed when metallic zinc is immersed in a similar solution.

Jan 5, 1913

By A. E. Schuetz, A. E. Roswell, W. R. Hibbard

THE drawn wire texture of body-centered cubic iron,' tungsten,' and molybdenum~ as been determined to be a [110] direction parallel to the wire axis. The purpose of this study is to extend the available information on body-centered cubic wire textures to other metals and alloys. Wires were produced using hand wire rolls and dies as given in Table I. In addition, attempts were unsuccessful to draw wires from chromium, vanadium (Vanadium Corp. of America), and tungsten (Cleveland Tungsten Inc.). Although it is known that wires can be made from these materials, suitable techniques were not readily adaptable. Where necessary, wires were polished and etched to form flat ribbons 0.005 to 0.007 in. thick, and transmission X-ray patterns were taken using molybdenum radiation with the specimen tilted 0 degrees from the perpendicular toward the beam to critically cover the wire axis. Analyses were made of (110), (002), and (112) reflection circles. In all cases reflection maxima indicated the texture to be a single [1101 deformation fiber, as illustrated by Fig. 1 for molybdenum. In the case of the hot-worked ß brass, a second texture, [loo], was also found, but this is believed to be the result of recrystallization since it has been reported for re-crystallized molybdenum wires' and it was not present in the cold-drawn ß brass. The difference in drawability between the 51.92 pct Cu ß brass and the 62.5 pct Cu ß brass (containing some grain boundary a due to incomplete quenching) is quite striking, since the latter could be cold worked readily while the former had to be hot worked to avoid cracking. Summary The deformation texture of drawn body-centered cubic wires of ß brass, iron, molybdenum, niobium, and tantalum is essentially a single [110] fiber as predicted by theory.' Acknowledgment The authors wish to thank the suppliers of the metals listed in the text, and the Grant-in-Aid from the Research Fund of the Society of the Sigma Xi and Scientific Research Society of America which made possible the purchase of X-ray equipment.

Jan 1, 1952

By Philip H. Nelson, Richard Lingle

Vibrating wire stressmeters (VWS's) and borehole deformation gages (BDG) were deployed in two in-situ heater experiments at Stripa, Sweden to determine the thermally induced stress changes in the rock mass. The heater experiments ran for 18 months, including a six- month cool-down period after the heaters were turned off. Gages were installed in both horizontal and vertical boreholes and were subjected to temperatures ranging from 10°C to 120°C, depending upon the distance of a gage from the central heater. Most gages operated in a moist environment because groundwater flowed into many of the instrument boreholes during the experiments Of the 36 VWS's installed, six failed. Failures were attributed to corrosion of the vibrating wire due to moisture entering the gage body. Of the 30 BDG's installed at the beginning of the experiments, 22 failed, also as the result of water entering the gage body. Modification and reinstallation of the gages eliminated the problem of water infiltration, but much data from early stages of the experiments was lost due to gage failures. Calibration of the VWS in blocks of Stripa granite showed a lack of repeatability. Variability in calibration results are attributed to seating effects, to variations in the elastic modulus of the rock, and to changes in temperature. These three effects combined to produce an error judged to be approximately ±33% of the stress changes measured at Stripa. In contrast, the major source of error in determining stress with the BDG appears to be the uncertainty in rock modulus and thermal expansion coefficient. Sample calculations based on data acquired near the end of the experiments (during cool-down)

Jan 1, 1982

By Irwin Roman

In a previous paper,l a method was suggested for determining the depth to a bed in the simple case of a uniform overlying layer of constant thickness. The main purpose of the present paper is to show how a slight modification of that method has been used to interpret specific data obtained in the upper peninsula of Michigan by the staff of the Depart- ment of Mathematics and Physics of the Michigan College of Mining and Technology. The method of Tagg2 has also been used on the same data, thus furnishing a comparison of the two methods, as well as a method of using the two methods jointly. The method of measuring the apparent resistivity is that suggested by Wenner,3 and illustrated in Fig. 1. A current I enters the earth at the positive pole C and leaves it at the negative pole D. The potential V of the high electrode A, with respect to the low electrode B is measured by suitable means. The separation of the collinear points in the order shown, DBA C, is I, the same for each interval. If the resistivity of the overburden is po, and that of the bed is pa, the apparent resistivity is given by

Jan 1, 1934

Report of President The important fact of the year 1916 is that on July 25 contracts were executed by which the American Society of Civil Engineers because an additional Founder Society and arranged to make its permanent home in our building. The contracts provide for the construction of three additional stories to the building, the American Society to pay the cost tip to $250,000, this being considered equivalent to what each other Founder Society had contributed, the American Society to participate in the original Carnegie gift and have an equal share in the property with each other Founder society. The construction of the addition to the building is under way, $62,525.04 having been expended thereon in 1916. It has been found that, clue to war conditions and the advanced price of materials, the cost of the addition will be $300,000. The founder societies have been requested to assume the extra $50,000, one quarter each. This work is in charge of a Building Committee consisting of H. H. Barnes, Jr., Chairman, E. G. Spilsbury, Charles Warren Hunt and Charles F. Rand. At the request of the Founder Societies, important alterations were made in the lecture halls on the fifth floor of the building to make the same suitable for social functions of the societies. The cost, $6,642.08, was advanced by the United Engineering Society but is to be paid eventually by the Founders. The Library of the civil Engineers is being merged with the Library of the United Engineering. Society and the other founder societies. At the present time the membership of the four founder societies is 29,000 and of associate societies 23,000, so that a total of 52,000 engineers now have their headquarters in our building. The value of the real estate now owned by this Society is $1,647,171.16. This sum will be increased at the end of 1917 by the amount of the cost of the addition to the building.

Jan 3, 1917

By H. E. Wrigley

The boundaries of the oil region in Pennsylvania and New York, as determined by the drill, embrace a much larger extent of territory than is generally supposed, being nearly 200 miles in length from north to south, with an average width of 25 miles, covering an area, within somewhat irregular lines, of about 4250 square miles. After twenty years of development we find these lines practically the same as those laid down by McClure in his geological map of the United States, published in 1817, and denominated and colored by him as the "line of salt," which was found in quantity long before petroleum. The eastern line of the entire oil region lies in a northeast and southwest direction, parallel to and some distance west of the Allegheny Mountains; the south line is substantially one drawn between the western boundary of Butler County and the town of Kittanning in Armstrong County; the west line passes just outside of Butler County, cutting off a small corner of Mercer, west of the towns of Franklin, Titusville, and Warren, into New York State, where it rounds off the end of this long strip in the counties of Allegheny and Cattarangus, and joins the eastern line, near Olean, New York, north of the city of Bradford. (See map.) The eastern line, starting from Kittanning, passes through the northeast corner of Clarion County, the southeast corner of Warren, cutting Forest County through the centre, and reaching the beforementioned extreme northeastern developments near Olean. These lines have been taken broadly to include all territory that could ever possibly come into the question as oil-producing. These lines having been proved by the drill may be considered

Jan 1, 1882

By Louis A. Mattson, Winthrop A. Rowe, John T. Cumberlidge, Victor M. Mejia

The parent ultramafic of Nickel Mountain is an alpine-peri-dotite. Compositional layering and late stage dunites suggest the intrusive crystallized in the upper mantle or lower crust. The ultramafic mass was fault emplaced in the upper crust, probably during upper Jurassic time. Soil, saprolite and silica boxwork nickeliferous ores were formed over the Nickel Mountain peridotite during the development and later destruction of the Klamath peneplane. A complex fault pattern was produced by irregular gravity displacements along fault surfaces during the relative uplift of Nickel Mountain. The majority of the ores occur in the fractured hanging wall of these gravity faults. Consequently, structure mapping is important for mining purposes. Ore types at Riddle are classified on the basis of MgO, Fe, and Si02 contents as well as textures. The chemical, mineralogical and textural differences of the various ore types reflect differences in weathering histories. Satellitic ore bodies occur peripherally to Nickel Mountain. These are erosional remnants of landslides and large gravity fault blocks from Nickel Mountain.

Jan 1, 1976

By Robert B. Fulton

Commercially, celestite (SrSO,) is the only significant strontium mineral. Among other strontium-bearing minerals, only strontianite (SrCO,) occurs commonly; however, it is not an item of commerce. The principal production of celestite is in England, Mexico, and Spain. New production is now coming on stream in Canada. Consumption is mainly in the United States. Lesser quantities are consumed in Japan and Europe. Main uses are for the manufacture of strontium carbonate and nitrate. The carbonate is used in glass for TV tube face plates and in ferrites for magnets. The nitrate is used in pyrotechnics to which it imparts a characteristic brilliant red color, mainly in safety flares. Minor amounts of strontium compounds are used in electrolytic zinc manufacturing and very small quantities in greases, ceramics, soaps, alloys, and pharmaceuticals. Specifications and Prices Typical celestite specifications for the carbonate and nitrate markets are as follows: [ ] Celestite currently shipped from Mexico for carbonate manufacture tends to be slightly better than these industry specifications, assaying about 92-93% SrSO, with less than 1% BaSO, but it is generally below the 95% minimum required for nitrate production. Contract prices for celestite are approximately $32-34 per st at U.S. Port of Entry in 50 to 60-ton carload lots for Mexican material. Spot prices are generally reported as low as $20 per st but are for minor volumes. A recent sale of surplus from the U.S. stockpiles, announced by the General Service Administration (GSA), was 4005 st sold to Du Pont for $140- 455 or $35.07 per st. British celestite, ground, washed, and graded, 95% SrSO, bulk, ex- works, 240 mesh, is quoted at £ 28.75 per mt in British trade journals, and a recent figure quoted for crushed lump material was $36.00 per st f.0.b. vessel Bristol Channel port (1973). Specifications of manufactured carbonate made from celestite and sold in two grades, one to the glass industry, the other to the electronic industry for ferrites, are given in [Table 1]

Jan 1, 1975