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By J. H. Polhems, R. B. Brackin, D. B. Grove

P. L. Jones (Sink and Float Corp., New York)—The comparisons between galena and ferrosilicon medium should be applied only to the specific sink-float process used at Mascot since no evidence is presented that allows the comparison to be extended generally to galena medium as now used in other forms of sink-float. It is stated that flotation recovery of galena medium was tried but was unsuccessful and therefore the elaborate gravity system of medium recovery was applied. The expense of the gravity system at Mascot was one of the reasons for changing to ferrosilicon. However two important sink-float plants treating a combined total of over 13,000 tons of ore per day are using flotation to clean galena medium most successfully and are obtaining medium recoveries comparable with those reported in the paper for ferrosilicon. Slightly increased zinc recovery is claimed due to the change-over but it is to be noted that at the time of the change a decreased density differential was obtained in the separator. With galena a differential

Jan 1, 1952

Discussion of the paper of P. B. LIEBERMANN, presented at the St. Louis meeting October, 1917, and printed in Bulletin No. 127, July, 1917, pp. 1051 to 1062. P. B. LIEBERMANN.-As mentioned in my paper, a special investigation was made on the effect of dirt on the track, for the -express purpose of educating mine operators to the advantage of keeping their tracks clean. As to the benefit of clean tracks to the saving in battery consumption, that can be easily determined if the rate of discharge is known under existing conditions, that is, on dirty tracks. The tests have shown that tracks covered with coal dust cause an increase in draw-bar pull of about 30 per cent. The battery discharge table will show the capacity corresponding to the new rate of discharge and will thereby disclose the possible saving in battery consumption. The difference between dirty tracks and clean tracks will be found large enough to have an appreciable effect on the size of the storage-battery locomotive, and for a locomotive of any given size it may mean

Jan 1, 1918

By John H. Bassarear, Harold W. Sorstokke

The never ending search for lower unit costs led Pima Min- ing Company's management to study various alternatives shortly after Expansion III was completed. A considerable amount of ore as- saying 0.35% copper had to be moved to maintain mill feed at the desired 0.54 % copper content, which is the overall grade of the ore reserves. Detailed investigations revealed that for a period of 8-10 yr, about 14,000 tpd of 0.30- 0.40% copper ore pass the crusher enroute to the low grade stockpile. This ore is very hard, very clean and has to be mined at a uniform rate. A six month pilot plant run testing autogenous and semi-autogenous grinding gave encouraging results. Since no mining costs need to be charged to the extra tonnage (it had to be mined anyway), the major costs would be against milling. The decision to proceed was made in August 1970. Fluor-Utah was retained as the prime design construction contractor. Ore was put through the new mill on December 29, 1971. By March of 1972 design tonnage

Jan 5, 1973

Open pit operators have found the dropball crane a great aid in cutting costs and hazards of secondary breakage. But a common problem in using the unit has been with the shock absorbing connection from the cable to the dropball itself. Blair Limestone Div. of Jones & Laughlin Steel Corp. has come up with a new connector to solve this problem and to save the time usually lost in frequent replacement of the cable slings, chains, or old tires hitherto used at this point. J&L personnel solved the problem by combining three ideas from other dropball crane owners. Their unit consists of two long U-bolts running through a heavy spring originally made for use on a vibrating screen. Heavy duty swivels attached to the bent ends of the U-bolts provide attachment points for the crane cable and the special chain to the dropball. Connection at the dropball is by an eyelet welded directly into the mass of steel, and a special alloy chain is connected to this with a clevis.

Nov 1, 1955

By James A. L. White

Of the natural elemental surfur deposits of the world, volcanic deposits are not only the most spectacular, but probably the most widely distributed. As defined for the purposes of this paper, volcanic sulfur deposits include those associated with all phases of volcanic activity, including eruptive flows, and fumarolic and hot spring deposits. The line of demarcation between the latter and sedimentary deposits is not always clearly defined. Although volcanic sulfur has played an important role for centuries, serving as essentially the only source of sulfur, currently it is considered as purely marginal material. Volcanic deposits were relegated to this position by the advent of Frasch sulfur into world markets, which established sulfur prices and annual production levels with which volcanic sulfur cannot compete, Since early in the 20th century commercial interest in volcanic deposits of sulfur has been high only when premium markets are available. This occurred in the early 1950s and is the case at present. Considerable effort is currently being expended to establish new producers of volcanic sulfur, and to expand current operations or reactivate previous ones.

Jan 6, 1968

By Anthony J. Chasteen

Although geothermal energy has been used by mankind for thousands of years and has even been used to generate electricity since the turn of the century, it is only in the last few years that the threatened energy crisis has focused attention on this resource. Geothermal exploration and development is being carried out in at least thirty-five countries on five continents. The status of geothermal energy production, however, is rudimentary with about 800 MW installed generating capacity worldwide, equal to about 0.1% of the world's total energy production.' The world's first (1904) commercial generating site at Lardarello, Italy, will soon be surpassed by developments at The Geysers, Calif. There are other successfully operating geothermal power projects in New Zealand, Japan, USSR, Mexico and Iceland with pilot plants planned or under construction in Chile, El Salvador, Nicaragua, Turkey and the Philippines. The preponderance of exploration and development is being sponsored or assisted by individual governments, by the UN or by the U.S. Agency for International Development

Jan 10, 1972

By E. Buehler

THE floating zone refining technique'-4 has provided a new experimental approach to the purification of many reactive materials especially those with high melting points. The method avoids the use of a crucible and at the same time it provides a favorable environment at the freezing interface for the growth of single crystals. The physical properties of refractory metals such as molybdenum and tungsten have long been of interest from a fundamental point of view and because of their widespread use in vacuum electronics. Single crystals are often desirable for study. Prior to the introduction of zone melting, single crystals of these metals were usually grown in the solid state at temperatures slightly below the melting point by strain annealing3 or by the application of a moving temperature gradient. Such techniques were mostly successful on wires, ribbons, or rods having small cross-sectional areas. Recently, larger samples of tungsten, molydbenum, tantalum, columbium, and rhenium were melted by a floating zone process which employed electron bombardment heating.10 Single crystals were obtained in many instances

Jan 1, 1959

Sifto Salt Div. of Domtar Chemicals Ltd. has developed a new method for installing roof bolts in the high backs of its 1-million-tpy rock-salt mine at Goderich, Ontario, on the east shore of Lake Huron. The method teams a telescoping- boom hydraulic crane with a specially developed combination auger-drill and bolt-tightening ma- chine. One man, controlling all operations from a basket supported at the end of the crane's telescoping boom, installs an average of 100 5-ft roof bolts per shift, at heights to 45 ft. The mine has very long backs that are not as stable as might be expected. The result has been that roof scaling has occupied an unusually high percentage of the underground work force. About six years ago, company officials decided to go to 100% roof bolting of all backs as a safety measure. The present roof-bolting equipment is the result of a development program instituted at that time to find a faster and more economical method for doing the job.

Jan 9, 1967

By F. X. Tartaron

The comparison of actual energy of comminution with theoretical surface energy presents a wide gap. On the other hand, Solid State Theory presents a viewpoint that places actual energy of breakage in understandable relationship with the theoretical strength of materials. Therefore the physical background of comminution theory favors Kick's Law. A11 discussions of comminution theory appear farfetched when comparison is made of the actual energy of crushing with the energy input called for by thermodynamic theory. Quoting Taggart:' "The work required to crush halite was of the general order of 0.10 kg cm per sq cm of new surface produced (based on air percolation) whereas the theoretical energy of this new surface, based on thermodynamic calculation by a number of investigators is 1 x 10'4 kg cm per sq cm or the work expended was 1000 times the new surface energy — an indicated crushing efficiency of 0.10 pct." It is frustrating to probe into comminution theory with the prospect that the energy one is measuring is 99.9 pct waste energy. Do the laws of comminution deal with energy consumed by mineral breakage or with waste heat energy? There seems to be something wrong. Solid State Theory may provide the answer. The following statement is particularly apt to the situation: "The fundamental fact about metals and indeed all materials, is that they are much weaker than they should be. By this, we mean that if the stress required to cause a given plane of atoms to slip past a neighboring plane is calculated from basic atomic and Solid State Theory, the resulting number is some 1000 times too large to be accounted for by errors in approximations or assumptions. We know now that this is due to dislocations, and we even have a fair understanding of the details of the process by which dislocations make a crystal weak. An intriguing possibility which suggests itself, results from the discovery of very minute metallic crystals which are apparently free of dislocations and which have a strength approaching the ideal value for a perfect crystal." Here we have an extraordinary reversal of the situation. The actual energy for breakage is only one-thousandth the theoretical instead of 1000 times as given by Taggart. But the theoretical energy presented by Solid State Theory is the binding energy between atoms (or ions) in a crystal lattice. This is the kind of energy envisaged by Kick's law. The surface energy or the other hand corresponds to Rittinger's law. Comparison of theoretical with actual, on the basis of surface or on the basis of Rittinger's law, seems to present an absurdity; yet Rittinger's law is confirmed by an impressive array of experimental evidence. Comparison of theoretical and actual on the basis of Solid State Theory or, in other words, on the basis of Kick's law seems reasonable; yet there is not a scrap of evidence to verify Kick's law. The situation appears paradoxical, but the developments in the next section of this paper show that the paradox is a hint to a strange turn of events. ENERGY-WEIGHT FRACTION FUNCTION charles3 has presented a final equation showing the relation of energy consumed in comminution to size of product n{-1) a-n + 1 E is energy, C is proportionality constant, a and n are constants and k is the coarsest size in the ground product (size modulus). In the course of study of a large amount of experimental evidence, Charles discovered that in the general case, a-n + 1 approximated zero. For some reason, a and n differed only by unity. But if a—n + 1 = 0 within experimental error, then it is obvious that Eq. 1 states that it requires an infinite amount of energy to grind any sample to any size. This is a case where nature gives an absurd answer to a man-made mathematical equation, hence something is wrong with the equation. An adjustment must be made to fit the equation with experience. TO reveal the nature of the adjustment, the differential equation preceding the second integration in Charles' group of equations is given When Charles integrated the quantity xa-n it was almost impossible for him to realize that he was dealing with a special case of integration and that

Jan 1, 1962

By C. H. Curtis

THE valuable mineral content of the current feed to the Miami concentrator is as follows: copper, 0.7 pct total; molybdenum, 0.01. Flotation of this ore yields a sulphide concentrate containing: chalcocite, 44 pct; molybdenite, 0.5; pyrite, 50.0; insol, 5.5. A combination of potassium ethyl xanthate and pentasol amyl xanthate as collectors, and pine oil, as frother, are used in this flotation. Rejection of pyrite is encouraged by holding the amount of collectors used to the minimum consistent with copper recovery and by operating at high alkalinity (equivalent to 0.35-0.40 lb CaO per ton solution of pH 11.0).

Jan 1, 1950

By P. Barnes

EXACT accounts have been kept of the cost of these chimneys, and it may be a matter of some possible interest that the plans and details of cost should be laid before the Institute. The statement of cost herewith submitted does not give minute particulars of the weights or quantities of material used, although these are noted upon the company's books.

Jan 1, 1876

By J. E. Warren

The mathematical problem considered by the author1 can be given another physical interpretation which is of some practical significance. The alternative physical problem involves the approximate behavior of a single well which is producing at a constant rate through an axially symmetric, horizontal fracture of infinite flow capacity which is located at the center, top or bottom of a uniformly thick, horizontal, homogeneous, anisotropic reservoir of infinite lateral extent which contains a single, slightly compressible fluid. Using Coats' asymptotic results, the wellbore pressure in the fractured system is given by the following equation.

By W. M. Albrecht, M. W. Mallett

The solubilities of hydrogen in titanium and several of its alloys were determined at 600 to 1000°C and pressures of 0.05 to 10µ of mercury. Solubility increases with increasing beta phase in the alloys. Factors found to affect degassing rates are specimen size and presence of thick surficial oxide. Removal of hydrogen by heating in vacuum and in flowing inert atmospheres was studied. Practical curves predicting minimum degassing times are presented. THE presence of hydrogen in titanium and titanium alloys has detrimental effects on the mechanical properties of the metal.'"," The hydrogen content of commercial titanium is sometimes of the order of 200 ppm by weight' and varies with alloy composition. As a consequence, titanium and some titanium alloys as normally processed are sometimes not ductile unless treated to lower the hydrogen content. The best known hydrogen-removal treatment is heating the material in a vacuum. The rate of removal (degassing) at a give temperature determines the duration of the treatment required to attain a satisfactory low hydrogen level.

Jan 1, 1959

By W. H. Emmons

Although gold is one of the rarer metals, it is widely distributed; it is found on all of the continents and in each of the grand metallogenic provinces of the earth. It is prominent particularly in the shield areas of the earth; these areas have produced a large part of the world's lode gold and in most of them gold lodes are more important than the lodes of other metals. The Scandinavian shield is the only one that has not produced much gold. Nearly all of the world's gold has been derived from lodes and from sands and gravels where gold placers formed by the destruction of lodes. The gold derived from magmatic segregations, from pegmatites and from contact metamorphic deposits is quite subordinate to that derived from auriferous lodes. The lodes include all veins and related deposits that are formed by hot waters that move along fissures or other openings and that deposit vein 'matter :in the fissures and by replacement of the country rocks along the fissures. All of the shield areas of the earth are characterized by large areas of granitic rocks including granitic gneisses, granodiorites and other acid intrusives which here are included in the general term "granite." The granites are intruded into schists, ancient lavas and other rocks which here are designated as the "invaded" rocks. The granites are parts of what once were great batholiths: that is, they are the remaining portions of great deep-seated bodies that slope outward, have very irregular roofs and so far as known have no floors but extend downward to great though unknown depths. Some of them are scores or hundreds of miles across and contain islands or "roof pendants" of the invaded rocks at places where the roofs of the batholiths were low—that is, where erosion has not yet completely unroofed the batholiths. It is in these islands of older rocks and in the narrow marginal belts and cupolas of the batholiths that practically all of the gold lode deposits of the shields are found. Valuable lodes are lacking generally in the granites themselves except in grahite within a mile or less from .the contacts with rocks of the islands (Fig. 1). It is probable that the great areas of granites and gneisses that surround the islands are not all of the same age, and that at places unmapped granite intrudes gneiss or older

Jan 1, 1932

By C. G. Albert

The clay particles of 2 microns or less required for modern paper coating are predominantly flat plates, lying smoothly on the sheet and producing a high gloss. Operating speeds of today's coating machines necessitate a clay composition of 60 and sometimes 70 pct solids as against the 35 to 40 pct required in the past. Since clays in suspension may solidify in flow, only those of intrinsically low viscosity can be used as high coating solids. THE literature of paper technology contains a number of articles having reference to developments in the field of coating and filler clays for use in paper manufacture. Much of this information has not been included in mining publications and has therefore not been readily available to all in the mineral industry. Recent developments in this field, including spray drying of clays, are presented here. U. S. Bureau of Mines figures for 1952 indicate that the paper industry consumes more than 50 pct of all kaolin produced and sold in the U. S. As most of the kaolin used by the industry comes from Georgia producers, the fraction of their output destined for paper use is thus appreciably higher than 50 pct. Small wonder that the kaolin industry, especially in Georgia, is highly sensitive to the quality requirements of paper mills and must respond promptly to technological developments in paper manufacturing. The paper industry itself is not the ultimate consumer. For the greater portion of the clay the end product is the printed page, and the demands of printing and publishing have sparked some of the technological advances in paper making which have, in turn, brought about methods employed in the kaolin industry. As compared with the product of 20 or 25 years ago, one of the most striking characteristics of the graphic arts today is the mass production of quality printing of fine pictorial work, much of it in full color. During this time periodicals with printing standards close to those of yesterday's slick-paper publications that were printed on a slow schedule and for a limited circulation have grown to the point where they go out to many millions of readers, often at weekly intervals. The complexity of technological improvements brought about by this increased circulation is probably not appreciated even by technical people, unless they have had reasonably close contact with the industry. The advance has come about through developments not only in the art of printing, but also in the field of paper making and even at the level of clay mining and processing. The smoothness required for faithful reproduction of the kind of printed matter under consideration is attained with a clay-coated paper. Since the distribution expense of the publication will depend to a great extent on its weight, the paper used must not be too heavy. This means a lower basis weight than was normal for conventional clay-coated papers some 25 years ago. And for this mass production market it becomes necessary to provide a paper having these and all the other required characteristics at a very moderate price—not the premium price conventional clay-coated papers formerly demanded. This challenge has been met by a new method of producing coated paper. In the past, application of clay coating to paper was a conversion operation, performed separately from the making of the base sheet. The newer development is called machine coating. Here application of the coating is an integral step in a continuous process by which wood pulp, clay, and other ingredients are manufactured into a sheet of coated paper. Many more problems are involved in this procedural change than are apparent at a casual glance. The coating operation, for example, must function at much higher linear speed than could be obtained with coating mechanisms previously employed. The application machinery developed to meet this requirement necessitated changes in composition of the coating color.* This created new requirements, summarized below, for the clay employed as coating pigment. In addition to smoothness, a relatively glossy printing surface is needed, and to a large measure it is the function of the coating clay to make possible the development of both these surface characteristics. Traditionally, pigments such as satin-white, prepared by reacting lime with paper-makers' alum, were used to assist in producing a high finish. However, economic considerations and others preclude large-scale use of such material in the new processes. In the 1930's Maloney' discovered that a certain particle size fraction of kaolin, consisting

Jan 1, 1956

By L. W. Blau

PERHAPS the most important event f or exploration geophysics in 1940 was the publication of three textbooks : "Geophysical Prospecting for Oil," by L. L. Nettleton ; "Exploration Geophysics," by John J. Jakosky; and "Geophysical Exploration," by C. A. Heiland. The literature had grown so bulky, and such a long time had elapsed since the publication of the texts by Ambronn and Eve, that treatises covering exploration geophysics comprehensively in all its branches and giving literature and patent references were sorely needed. This need has been satisfied admirably in these textbooks, and geophysicists owe the authors a debt of gratitude. In 1940, geophysics came of age. A conference on applied nuclear physics was held at Massachusetts Institute of Technology from Oct. 28 to Nov. 2. Several papers on geophysical subjects were presented at this meeting. Geophysical activity has decreased in all parts of the world except perhaps in Canada where, under the stimulus of the war's increased demands, prospecting for oil has increased. However, even there the war has had a seriously adverse effect on prospecting for ores and upon the promotion of new properties, although activity in producing and near-producing mines has been stimulated.

Jan 1, 1941

With this issue of the Bulletin, the Institute puts into operation a plan which it has long had under consideration for enlarging its field of usefulness to its members. We refer to the Index to periodical literature bearing on mining, metallurgy, and related subjects, which will be found in the advertising section at the end of the Bulletin. The Index is printed on alternate pages so that anyone who desires to compile a card index can readily clip the items and paste them onto cards. By its affiliation with the Engineering Societies Library, the Institute possesses unexcelled facilities for the preparation of this Index, since practically every important engineering or technical paper published anywhere in the world is regularly received by the library. The items for publication in the Index are first selected by the library staff, but their final approval and their order of arrangement remains in the hands of the editor. A word should be said in explanation of the system of classification that has been adopted. It will be noted that the classification is extremely broad, no attempt having been made to gather the references into closely specialized groups. Our reason for breaking away from the modern tendency toward minute specialization is based upon the fact that the fundamental principles underlying all engineering are not by any means so diversified as has commonly been supposed. For example, it is not at, all unlikely that an engineer engaged in large-scale ore mining in the Southwest can profit by observing the methods employed by his colleagues in the Pennsylvania coal mines. It is notorious also how extensively the brotherhood of chemical engineers has profited by the. earlier experiences of the ore-dressing and metallurgical engineers. If the Index were minutely sub-divided, it would always be possible that the coal-mining engineer, for example, might fail to observe a most important paper because it happened to be listed tinder the head of iron mining. For this reason, mining practice in general is consolidated under one head. The same line of reasoning applies to other divisions as well. In order to make the Index of practical value to all members of the Institute, wherever they may be situated, the library will undertake to supply, for a nominal charge, an abstract, a translation, a typewritten copy, a photostat copy, or the original of any article in the Index. Requests for service of this character should be addressed directly to the Engineering Societies Library, 29 West 39th St., New York. Members are urged to cooperate toward the success of this new departure by sending us suggestions. Although every effort has been made to anticipate the wishes of the members, it is almost impossible to foretell what services may be most useful to our 7000 constituents. Furthermore, it is known that some men prefer one method of classification while others would find another method more convenient.

Jan 9, 1918

By Ward W. Minkler

Since 1978, the titanium metals industry, throughout the non-socialist world, has experienced a period of growth and prosperity unparalleled since the late 1950s. Sponge producers, melters and mill product manufacturers have operated at capacity, record shipments have been attained, new producers have entered the industry and established producers have implemented expansion plans. However, there is now mounting evidence that the underlying elements which generated this vigorous surge have abated, at least temporarily. It now appears that in 1982, the industry will encounter overcapacity, excessive inventory accumulations and the probability of declining prices. Therefore, it does seem appropriate that we now take inventory of the present and future markets for titanium with the hope we can identify both near term opportunities as well as challenges the industry now faces. If we view the development of titanium markets as a function of time, they fit rather neatly into three sectors.

Jan 1, 1982

By Arthur B. Foote

THE ball mill has superseded stamps for the reduction of gold ores in most of the recently designed plants, partly because stamps are not suited to die fine grinding required for flotation, and partly to save space and construction cost. Experience with these new mills seems to confirm the idea that it is more difficult to recover bold from a ball-mill product than it is when stamps are used for crushing. Microscopical examination of particles of gold that have passed through a ball mill show that the gold has been pounded into exceedingly thin flakes coated with a talcy surface, making it more difficult to save by amalgamation, flotation, or concentrating. Bearing in mind that gold is extremely malleable, it seems reasonable that this should be so. Contrast the action in a stamp battery, where the crushing is by impact in the presence of mercury, to the grinding and rolling under pressure in a ball mill. It is well known that a better recovery can be obtained by panning or amalgamation from a sample of ore that has been crushed by mortar and pestle than from one reduced on a bucking board.

Jan 1, 1937

By E. D. Fields, M. C. Tippett, S. W. Sayers

The Copper Canyon and Copper Basin properties of Duval Corp., in Lander Co., have been recently added to the list of porphyry copper mines in Nevada, marking the first new copper open pit operations in this state in 15 years. Ore is processed in the 4000 tpd flotation mill at Copper Canyon, with some copper being recovered by dump leaching. The ore from Copper Basin, 10 miles northeast of the Canyon, is trucked to the mill for concentration. Cost of developing the properties is estimated at $22 million. It was recognized at an early stage of exploration that the two deposits were quite different. Continuity, mineralogy and grade of ore are much more uniform in the Canyon than in the higher grade, pod-like deposits in the Basin. The fundamental difference between the two areas is that the Canyon mineralization is dominantly hypogene, whereas the Basin ores are secondarily enriched.

Jan 3, 1968