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By Robert C. Meaders, Arthur R. MacPherson

Many attempts have been made to eliminate most of the crushing plant and all the grinding plant in the process of ore beneficiation by substituting a combined crushing and grinding unit which could take coarsely crushed ore and reduce it to a fine size in one unit. This unit normally would have no other grinding media than the ore itself. This is true autogenous grinding, as we understand it today, and should be clearly distinguished from pebble mill grinding, where pebbles are substituted for steel balls to grind a ball mill size feed. To compete in efficiency with normal methods of crushing and grinding, the autogenous mill must use less labor and steel to produce an equivalent product at equal or lower power consumption. In general terms, a unit to perform these functions must have means to crush the ore to fine sizes and to then further reduce the crushed pieces by grinding. In other words, to do efficient autogenous grinding, there must be a proper balance established between crushing and grinding rates. There is not much point in crushing at too fast a rate if the grinding means are not present to reduce the small particles to the required product size. The crushing means used in an autogenous mill are impact forces of two kinds, namely, (1) the rock travelling at high speeds striking the shell, and (2) the lifters travelling at high speeds striking the rock. Grinding is probably effected in a manner equivalent to pebble milling.

Jan 9, 1964

By J. C. Williams, M. J. Blackburn

In recent years examination of thin foils of metals and alloys has been widely used in studies of deformation and phase-transformation mechanisms. Applications of this technique to studies of titanium and titanium alloys have been infrequent. Therefore, as a large number of titanium alloys have been investigated in this laboratory, it is proposed to give an account of methods used. Particular emphasis will be placed on some of the artifacts introduced in thin foils of titanium and titanium alloys during preparation. Experimental Procedure. It has been found that a large number of titanium alloys can be electropolished in a solution consisting of 30 cu cm perchloric acid (60 pct), 175 cu cm n-butyl alcohol, and 300 cu cm methyl alcohol. Thin foils are prepared using the window method and the electropolishing conditions listed in Table I. Although this solution is not unique, it is attractive because of its low concentration of perchloric acid and the wide range of alloys for which it can be used. Electropolishing is conducted at below -25°C as above this temperature a brown anodic film is produced on the specimen surface. Temperatures above -25°C also accentuate preferential attack of the 0 phase in the two-phase alloys, which unfortunately occurs at all temperatures. Contamination. It is advantageous to reduce the specimen to a thickness of 25 to 50 p prior to electropolishing, since the low-temperature electropolishing technique results in a low rate of metal removal. Both chemical polishing and grinding have

Jan 1, 1968

By H. W. Hardinge

Disregarding for the present the economic side of a new device, let us turn to that feature of the conical pebble-mill which is of interest from a scientific point of view, and consider the device as a puzzle in which the theories of the cylindrical type of mill have been increased. Many articles have been written on the theory of the tube-mill, and explanations have been made which do not explain ; but these have evolved suggestions of practice which have resulted in changes in the tube as to length, diameter, feed, discharge, speed of rotation, rotation on hollow trunnions, rotation on rings, and changes in the operation as to quantity and size of pebbles, charge of load above or below the axis, crushing by causing the larger pieces of the material of the charge to act as grinders, whether crushing is abrasive or impactive, etc. The practical worker in crushing. is first interested in the endeavor to reach an econonlic means of accomplishing a desired end; but the improvements in crushing-practice have been largely left to the manufacturer of machinery, who, as a rule, has little, if any, knowledge of the specific requirements— such as granulation, sizing for concentration without pulverizing the metals, instead of pulverizing the rock or gangue; the metals being the more friable, while the rock is tough and not so easily disintegrated. A reversal of this practice is the aim of sliming direct for cyanidation or pulverizing for cement, etc. In the ordinary cylindrical mill, having a diameter of 4 or

Jan 1, 1909

Works Manager or General Superintendent.-Technical graduate, for position with a company whose works consist of a large machine shop and foundry. This company manufactures well-known power plant equipment. Location, Pennsylvania. Salary, $5000-$8000 per year. R-871. Motion Study Engineer with extensive experience in shop operation and motion study. Must have sufficient technical experience to recognize inefficiency and waste in plant. Salary, $175-$200 per month. Location, New Jersey. R-876. Metallurgical Engineer.-Technical graduate with at least 2 or 3 years' practical experience in the operation of zinc smelters. Duties will be to take charge, under the guidance of -the superintendent of the smelter, of the operating end of the furnaces, and the roasting kilns, as well as the mix room and ore crusher. Man desired should not be over 30 years of age and should be progressive and able to handle men. Salary, $250 per month. Location, Oklahoma. R-877. Private Secretary to Vice-president in charge of development department and laboratories of large manufacturing plant; must be technical man of good personality, and A-1 in every respect, as position is an important and responsible one. Location, Ohio. R-896. Sales. Engineer familiar with his local territory, particularly with the fanning trade. Should have had at least 2 years' experience in selling tractors; and in any event, must have had at least 5 years' experience in selling machinery. High grade, energetic, and capable; man who is not satisfied with less than $3000 per year and who can earn up to $7000. Location, Iowa. R-897.

Jan 8, 1919

By Josef Westesson

No question in the metallurgical chemistry of the present day seems to be so difficult to agree upon as the determination of phosphorus in iron and steel. To my knowledge, there are at present at least three different methods in use in the iron laboratories of the United States, viz.: The citric acid method, the molybdate-magnesia method, and the direct molybdate method,—the last-named method having been lately adopted. Each of these methods has its advocates, who take every pains to prove its advantages, and the incorrectness of the others; and much has been written for the purpose of securing the use of a standard method—as yet, however, without any result. There is no doubt, or ought to be none, that each of these methods gives correct results, when it is carefully conducted and every precaution is taken. But it is not only correct results that we want nowa-days. The demand is great, also, for getting results in the shortest possible time. I think it has been sufficiently proved that the direct molybdate method, the weighing of the precipitate, answers well in both respects. Being a pupil of Prof. Eggertz, I have myself used his method for years until quite recently, as it is described by Mr. Troilius in our Transactions, vol. x., p. 166 (but with some slight modifications), and I can safely say that the results of this method agree well with those of the molybdate-magnesia method. I have, moreover, been checked, in a few instances, by some of the

Jan 1, 1885

By Mark R. Lamb

The various methods of treating pulp in air-agitation tanks offer problems for experiment and study which are fascinating as well as practical. The usual method heretofore has been to fill each tank in turn, agitate the mixture the required period and then discharge the treated pulp into a storage-tank, from which it is drawn to the filter as required. A later method is to run the pulp from the tube-mill, classifier, thickener, or settler into the first of a set of tanks, and thence continuously or in series through the remaining tanks, finally drawing off the pulp to a continuous filter, or to a pulp-storage tank if the filter is of the intermittent type. It is this method which I propose to discuss here in a preliminary way, with the idea of going exhaustively into the examination of the results of a series of experiments in a later paper. It may be of interest to note that the design of a cyanide-plant has recently been completed in which the estimated cost of the agitation-tanks, storage-tanks, and pumps was 30 per cent. higher for the charge-agitation arrangement than for the series plan. The first question in studying the series method is, " What is the actual period of treatment undergone by the pulp ?" One first supposes that by chance some of the pulp may get through with little or no treatment, while other portions may stay in the tanks a needlessly long period. The former is not probable or even possible, and the latter is, practically, true

Jan 1, 1910

By Walter Weeks

THE subject of the flow of air through a mine under the influence of natural ventilation has proved an elusive one. To my knowledge only cut and try algebraic solutions have been used where multiple paths are involved. The object of this paper is to present a method for the graphi-cal determination of the flow induced by the natural ventilation pressure (N.V.P.) alone or in combination with a fan. The N.V.P., measured in pounds per square foot, induced by two columns of air between two horizontal planes at different elevations, is equal to the difference in weight of the two columns, assuming each to have a cross-sectional area of 1 sq. ft. Pressure in pounds per square foot is converted into inches of water by dividing by 5.19. Methods of calculating the N.V.P. have been discussed in the litera-ture. In this paper, for simplification of exposition, the change in pres-sure due to the weight of superimposed air will be assumed directly proportional to the length of the column. The actual methods of cal-culating the N.V.P. do not affect the solutions to be presented. It must be realized that the precision to be obtained from the small-scale, inked diagrams presented is not as great as would be obtained from large-scale, penciled curves that would he used in practice. The accuracy of the curves does not warrant reading "volumes" closer than the nearest thousand cubic feet per minute.

Jan 1, 1938

By Donald V. Fites

In the face of an increasing demand for minerals, the resulting technological developments, and rising overburden-to-ore ratios, many open-pit mines now incorporate totally different concepts for the removal of ore and overburden. Moreover, under a growing number of these concepts, wheel tractor scrapers are being assigned a major role in material- handling systems for unconsolidated overburden removal. To say that scrapers move only unconsolidated overburden is incorrect. On the contrary, ripped phosphate rock, copper ore, iron ore, and moderately consolidated overburden are also being moved by scrapers in various areas of the world. According to the Minerals Yearbook, about one half of the material moved in metal and nonmetal mines is never drilled, blasted or broken by other means. Scrapers Find Wider Application The increased use of scrapers in open-pit mining today is due in part to improved design which has endowed these units with added versatility and in- creased their production capability. The modern scraper, which is designed as a loading and hauling vehicle, cannot be compared to the original tractor- drawn scrapers which were limited in capacity, maneuverability, and speed. Improved design of the scraper bowl ejection system has aided production. Gravity ejection has been replaced with positive, forced ejection of material by hydraulic or mechanical action. Bowl and cutting-edge design which allows for maximum load with minimum effort has also increased production. An example of this was the introduction some years ago of the low-silhouette scraper bowl which reduced the work required to lift the material.

Jan 5, 1969

By William G. Pariseau

A plasticity theory for anisotropic geologic media has been applied to the problem of quasi-static wedge penetration of rock under confining pressure. Numerical evaluation of the governing system of stress equations in the transversely isotropic and orthotropic cases using representative material properties shows that the consequences of initial anisotropy for the penetration process are by no means trivial. In the transversely isotropic case, a threefold increase in the vertical force required for penetration to a unit depth occurs as the inclination of the axes of anisotropy are rotated through 90° with respect to the penetration path. The horizontal force required varies from zero to a maximum at approximately 60° then back to zero as the axes of anisotropy are rotated. The maximum is of the order of magnitude of the force required in the isotropic case. Similar results are observed in the orthotropic case. Practical aspects of the post-elastic phenomena associated with anisotropic rock indentation within the context of drilling problems include: bit yaw, hole deviation and bending stresses in the drill rod, all of which vary with strata dip but which can be quantitatively evaluated given the bit geometry, interface friction and rock properties. In a broader context, the analysis reveals the necessity for well conceived experimental work and sound theoretical research concerning post-elastic behavior of geologic media as a function of confining pressure, the effects of induced anisotropy, and the variation of strength parameters with loading path changes in the post-elastic range.

Jan 1, 1971

By Henry M. Howe

This paper gives the results of an investigation of the beha vior of the argentiferous cobalt-nickel arsenides of Temiskam-ing, Ontario, in roasting, made in the metallurgical laboratories of the School of Mines of Columbia University in the City of New York. The ore was kindly given by the owners of the La Rose and Trethewey properties at Cobalt, Ontario, and Mr E. J. Hall, Tutor in Assaying in Columbia University, has helped us much. I. Object of the Investigation. The object of the investigation was to learn: 1. The temperature at which the arsenic is most rapidly expelled ; 2. The thoroughness with which it is expelled by prolonged roasting at this temperature; 3. The effect of adding charcoal (a) near the end of the roast and (b) at. the beginning of the roast. II. Nature of the ORe. The important ores mined in the Temiskaming deposits are: native silver—with small amounts of dyscrasite (Ag,Sb), ar-gentite (Ag,S), pyrargyrite (Ag,SbS,)—smaltite (CoAs,), chlo-anthite (NiAs,) and niccolite (NiAs). Mispickel (FeAsS) and cobaltite (CoAsS) also occur in smaller quantities. The average composition of the ore shipped from this district for the first six months of 1905 was: silver, from 4.1 to 4.8 per cent.; cobalt, from 6.9 to 8.2 per cent.; nickel, from 3 to 4.7 per cent.; and arsenic, from 30.9 to 34.6 per cent. The ore which we treated consists chiefly of smaltite. In our 1aboratory-work

Jan 1, 1908

By C. W. Purington, H. B. C. Nitze

The Kotchkar mining-district, known as the Kotchkar System, is situated in the Orenburg government, in Eastern Russia, in the great plateau- or steppe-country immediately adjacent to the eastern slopes of the Ural mountains. Its longer dimension is north and south about 27 miles, while in the widest (northern) portion the distance across is 22 miles. The district lies 40 miles southwest of Miass, a station of the Trans-Siberian railway, and half-way between this village and that of Troitsk. It contains also the not inconsiderable settlements of Kotchkar and Eosobrodskoit., the last a Kossak town. So far as explored, the district is known to contain from 300 to 400 auriferous veins. ? Although the topography is generally of an exceedingly flat character, the country is traversed by several small rivulets running from west to east, and flowing into the Sanarka and Kamenka rivers. Since 1844 placers have been worked in the district, but it was not until 1867 that veins were discovered, and these have been worked only since the impoverishment of the alluvial deposits. The deposit with which this paper especially deals is known as the Ouspensky mine, one of twelve owned by MM. de Zelenkoff & Cie., five of which are situated in the Kotchkar System. An opportunity of visiting this mine was afforded the writers, in eonnection with an excursion of the VII. session of the International Geological Congress; held in Russia during the summer of 1897. The mine is reached by a 40-mile '(troika" journey from the railway station of Bichkil, itself

Jan 1, 1899

By Malcolm J. McPherson

INTRODUCTION The use of computers to assist the mine ventilation engineer began to grow in the early 1950s when electrical analogue devices were developed for the analysis of mine airflow systems in Europe and the United States (l,2,3). The need for quantitative planning of airflows in mines had become pressing and analogue computers fulfilled a useful purpose for over a decade. From about 1964 onwards, digital computer programs for mine ventilation network analysis became available (4,5) and, superseding the analogues, spread rapidly throughout the major mining countries. The successful implementations of such programs resulted in further research being directed towards the development of simulation programs to model the quality as well as the quantity of air flowing through underground workings. It is no understatement that digital computers have revolutionised environmental planning techniques in modern mining industries. This paper discusses the complex interaction of natural and mining factors which governs environmental hazards in underground mines and further indicates some of the simulation techniques which have entered practical usage or are at an advanced stage of development. THE PROBLEM OF ANALYSING THE MINE ENVIRONMENT The traditional methods of approaching environmental problems underground were based largely on empirical or intuitive techniques. The reason for this lay in the intricate relationships which exist between the many variables that influence the mine environment - and which limit the use of purely analytical methods to the simplest of cases. In order to illustrate the need for simulation techniques, Table 1 shows the three most widespread mine environmental hazards

Jan 1, 1977

By Eben E. Olcott

The Mine.—For some years attention has been drawn to the copper deposits of the Appalachian range of mountains, and especially to those in that portion crossing the corners of Virginia, North Carolina, and Tennessee. Certain it is that in many places in this locality available deposits of copper await the miner, and one after another are being opened and worked. The parts of these three States alluded to are but sparsely settled, and communications are insufficient to meet the demand for transportation. Railroads are wanted, as the existing wagon roads are unfitted for heavy hauling; these circumstances increase very much the difficulties in the way of mining enterprises. Notwithstanding this, the success of some of the mines of this section is an established fact, and Ducktown has for some years held a high rank among the copper-producing localities of the United States. of all these deposits, however, none is more interesting or more deserving of attention than the one now under consideration. The works of the Ore Knob Copper Company have been energetically pushed forward, since the reopening of the mine, in the spring of 1873, by Mr. J. E. Clayt,on, the superintendent and one of the chief owners of the property, and if one thing more than another can insure success it is the combination in this gentleman of rare business capabilities with the deepest personal interest in the prosperity of the undertaking. The copper vein at Ore Knob* is a clearly defined fissure traversing the gneissic rocks of Pre-silurian age in a direction 61' east of north.

By D. L. Katz

A PHASE diagram showing boundary curve and quantity of liquid in the two-phase region was determined for a mixture of natural gas and natural gasoline in the region of its critical conditions. The tempera-tures and pressures of phase measurements were in the range of 85° to 212° F. and 1300 to 2600 lb, per sq. in., respectively, with the critical conditions at 169.5° F. and 2615 lb. per sq. in. abs, Color phenomena were observed in the region of the boundary curve from 102° to 192° F. Approximate densities of the single-phase and two-phase regions and analysis of the system are included. Boundary curves between the single-phase and the two-phase regions have been determined for several binary mixtures containing hydro-carbons. 2,3,4,6,7,10,11,12,14 These investigators did not report the relative amounts of liquid and vapor within the two-phase region. The equilib-rium values obtained from the dew-point and bubble-point data can be used to compute the lines showing percentage of liquid on the pressure-temperature phase diagrams but the positions of the lines near the critical temperature and pressure are uncertain. Relative amounts of vapor and liquid were obtained for a gasoline and a naphtha' within the two-phase area but not in, the region of the critical temperature and pressure. The bubble-point and dew-point lines, as well as the percentage liquid lines within the two-phase region, were determined by visual observations in glass apparatus.

Jan 1, 1939

By Wells A. Hutchins

Water laws important to the mining industry are those which govern or affect the right to use water, to dispose of water after using it in mining or milling, and to discharge waste material into water-courses. They include statutes and court decisions having general applicability, as well as others that pertain specifically to mining. THE INDUSTRY'S CONTRIBUTION TO WESTERN WATER LAW Despite sharp differences of opinion, the water law the Spaniards brought to the Southwest appears to have included some form of appropriation of water. The Mormons, who settled in Utah in the mid-nineteenth century, also developed a system of appropriative water titles. But by far the most profound impact on western water law was made by the gold- seekers who flocked to the Sierra Nevada foothills of California after the discovery of gold in 1848. Much of the gold was extracted from the ground by hydraulic or placer mining, and so the-miners' rights to the use of water became fundamentally important. Since there was no organized government in the foothills and no laws other than those made by the miners, they helped themselves to the land, the gold, and the water needed to work their claims.' They established and enforced regulations governing the acquirement and holding of mining claims and their rights to the water they needed.'In 1879 Justice Field, former Chief Justice of the California Supreme Court, spoke for the U. S. Supreme Court in saying that the miners were "emphatically the law-makers, as respects mining, upon the public lands in the State.""

Jan 2, 1960

By W. C. McClain

In the design of underground excavations, rock mechanics considerations are nearly always based on an elastic behavior of rock. Most rocks do exhibit a certain amount of elasticity, and the application of principles and concepts of elasticity to rock mechanics problems has been largely responsible for progress in the field over the past 10 or 15 years. NO doubt the theory of elasticity will remain the most useful analytical tool available for both the design of underground openings and the interpretation of phenomenological data. Dr. Cook's analysis of rock behavior based on energy considerations represents a significant new approach to mining rock mechanics problems. Although the foundations of this analysis are somewhat broader and more general than elastic analysis, the development and applications are grounded almost entirely in the theory of elasticity. It has long been known1,2 that all rocks, even granites and dense limestones, exhibit nonlinear time-dependent strain properties to a greater or lesser degree. Creep strain (that is, deformation under constant stress) in salt, potash, and trona can be several orders of magnitude greater than instantaneous elastic strain. Design of underground workings in these materials must incorporate provisions for these strains and must therefore go considerably beyond elastic analysis. Some of the principles of underground design in highly plastic materials will be discussed in this paper. Since all rocks, especially when highly fractured, exhibit a certain amount of creep-type strain, these concepts should be at least recognized in any rock mechanics problem. The discussion will be illustrated largely, but not entirely, by examples drawn from

Jan 1, 1967

By L. C. Weiner

THIS study was undertaken to round out an investigation on the effects of solid environments on the brittle fracture of zinc single crystals.' In the previous work it was demonstrated that the presence of a surface film increased the cleavage strength of crystals whose basal planes were oriented almost parallel to the tensile axis by some 43 pct. This increase was observed to be independent of the type of surface-coating material, as well as of thickness of film above a certain small critical value (about 200 to 300A). These observations were described sat- isfactorily by a dislocation-pile-up-at-a-barrier model of brittle fracture2 in which twins modifying the dislocation path act as barriers, their increase in number and homogeneity of distribution brought about by the presence of the surface film. From previous work reported on the strength of ductile metal crystals as affected by gaseous and liquid environments,3 it may be concluded that the effects of these media are present only when the environment produces a surface film on the initially clean-surfaced crystal, or when it has a disintegrating effect on a previously existing surface layer. Similarly, it might be expected that an increase in cleavage strength of initially clean zinc crystals (xo = 3", A, - 28") will result only when the gas or liquid reacts with the crystal to produce a solid, adherent surface film. Clean-surfaced crystals,l 2 1/12 in. in length, were tested in tension at room temperature in an Instron

Jan 1, 1959

By Manuel Valerio Ortega

This Mexican amalgamation-process, invented in 1557, at Pachuca, by Bartolome de Medina, has been widely discussed in America and Europe, but thus far there is no universal agreement as to all the chemical reactions involved. Having been, after many trials, the first to succeed in effecting the amalgamation of silver-ores by the same mechanical means, but doing without one of the chemical substances which had been considered indispensable in the practice of 300 Sears, I am led to offer these notes as a contribution to the discovery of an exact theory concerning the patio process. My treatment for silver- and gold-ores being protected by letters-patent in this country, the United States, France, Peru, Bolivia and Chile, I may speak freely concerning its materials and manipulation. I. Patio-Amalgamation. The ore extracted from the mine is sorted by pepenadores, who break the large pieces with hammers, rejecting those which contain no ore, set aside the very rich to be smelted, and deliver the rest to be crushed and pulverized for direct amalgamation in the patio. The broken lumps, of about fist-size, are first ground in Chilean mills, and then reduced, in arrastras or tahonas, to fine slime. After the lama or slime has acquired a suitable consistency by the evaporation, through the sun's heat, of a part of the water which it contained, it is spread upon the patio or amalgamating-floor, where it is mixed with 5 or 6 per cent. of common salt. The next day a certain amount (depending upon

Jan 1, 1902

By W. K. Tony Seiler

Further development of mechanical boring machines for hard and abrasive rocks will be effected by the development of more efficient rock cutting tools or the evolution of entirely new rock excavating principles. Presently the cutting tools suitable for extremely hard rocks and successfully and economically used with raise and tunnel boring machines are tungsten carbide insert big hole cutters. This paper explains the design, rock cutting principles, and actual boring operations to illustrate the capabilities and applications of tungsten carbide (TC) insert cutters. While the rate of borehole advance may fall short of the rapid excavating results achieved with soft rock boring machines, the cutter described in this paper may prove to be the most suitable tool in hard rock excavation for many years to come. DEFINITION OF HARD ROCK Existing bored excavations in hard abrasive rocks are proof of the economic application of new methods and mechanical rock boring in the mining industry. Most of the experience in cutting hard to extremely hard rocks has been gained in raise boring where relatively short and small diameter openings are bored. This poses a lesser risk regarding cutter cost than a long and large diameter tunnel and has therefore promoted the testing of various cutter products. Many types of rocks and geologic conditions were en- countered and actual test data was recorded in materials of up to 100,000 psi uniaxial compressive strength. To clarify the term hard to extremely hard, a 1970 interpretation of rock strength which was recently used is adopted and expanded in this paper.

Jan 1, 1971

By John Boardman

THE Anaconda company has never indulged in any employee activities at Butte which might be termed paternalistic, but it has exerted a vast amount of effort in care of its employees during working hours. The reason for this policy is not lack of interest or that the company does not feel the effect of employees' activities while they are "off the job"; it is that the company and the city of Butte have grown up together and, each has been adequate in its own sphere, the company in providing employment at the highest possible wage and the city in providing housing, sanitation, commercial services, medical services, schools, churches, amusements and entertainments. The one exception to this independence between the company and the community is the Butte Water Co., which is a wholly owned sub-sidiary of the Anaconda Copper Mining Co. Mention of this relationship is made here because the water supply of such a city as Butte is one of the principal factors in determining the health of the people. Very early in the development of the Anaconda company an adequate and dependable water supply for the operations became necessary, therefore the company took over this important community function. So well has this activity worked out that during the whole period of time covered, in which the company has expanded to become practically the sole mine operator and the community has grown from a small mining camp to the status of a modern city, there has been no shortage of water or any outbreak of water-borne, epidemic disease.

Jan 1, 1938