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By M. E. Wadsworth, I. B. Cutler

Coprecipitation of anionic and cationic polyelectrolytes has been applied to floccula-tion of several mineral systems. Results obtained in a study of the flocculation of kaolinite and hematite suspensions of polycationic and polyanionic electrolytes are presented. Greatly increased settling rates were observed following precipitation of positive and negative polyelectrolytes on the surface of finely divided minerals in aqueous suspension. The ratios of polycationic to polyanionic electrolytes required to produce maximum sedimentation have been shown to correspond closely with the equivalence points obtained by light scattering studies of systems containing the positive and negative polyelectrolytes by themselves. DISPERSION of colloids has been of interest to surface chemists for many years. Flocculation studies have been employed to evaluate the limits of colloid stability. In water suspensions, colloids become unstable and flocculate when the ( potential, the potential of the kinetic solvation sheath, falls to a value at which van der Waals forces may act to draw the particles together. This may happen through an adjustment of the pH of the suspension or by addition of a salt. Optimum conditions for rapid formation of large flocs are found in the region of minimum ( potential. In addition to these well known considerations, colloids in water suspensions are known to be flocculated by certain large organic macromolecules. These polyelectrolytes in some cases minimize the i potential and in other instances increase the attractive forces by supplying sites for hydrogen bonding.' Use of organic polyelectrolytes in flocculation of mineral colloids has increased rapidly in recent years. These materials are now recognized as indispensable aids to fluid-solid separations in many extractive metallurgical operations. They have been found to increase both the settling rate in thickeners and the filtration rate of filters. In the elucidation of the characteristics of these organic reagents as floc-culants in this laboratory, it was discovered that interaction of certain polyelectrolytes had a surprisingly good effect on flocculation of mineral colloids. Experimental Procedure: The anionic flocculants used in this study were Lytron 886 and 887, produced by Monsanto Chemical Co. Both reagents are copolymers of vinyl acetate and maleic anhydride. Lime is added to Lytron 886, whereas Lytron 887 is all organic. These reagents possess two carboxyl groups for each acetate group and are therefore anionic in character. The cationic reagents used were the Peter Cooper Co. 1-X and 2-X glues. The structures are not definitely known, but the re- agents are amines and are cationic in character. The glues were prepared in the chrome-alum form. Both types of reagents may be classified as polyelectrolytes in that they are high molecular weight polymers and ionize in water. All data presented are in terms of sedimentation rate, measured in 250-ml glass-stoppered graduated cylinders. With suitable precautions such measurements are fairly reproducible and provide a sensitive means for selecting important parameters such as pH, reagent concentration, and floc size and density.2 Agitation was standardized with five complete end over end cycles of the suspensions in the stoppered graduated cylinders.

Jan 1, 1957

By B. G. D. Smart

An understanding of the nature of yield zones surrounding coal mine excavations is fundamental to the design of mine support systems. Various methods have been designed for investigation of underground rock masses and an extensometric technique, the Magnetic Rod Extensometer, has been developed to overcome inherent design limitations in existing equipment of this type. This paper refers to the prototype form of the extensometer and details changes designed to overcome a variety of drawbacks indicated by routine use of the equipment. The principal change has been one of manual to computerised data acquisition and presentation in the laboratory phase of the system. This has dramatically reduced the time taken to process underground measurements and produce numerical and graphical results. The revised Magnetic Rod Extensometer represents an integrated instrumentation system that combines speed and accuracy in all areas of data handling.

Jan 1, 1984

By J. W. Spretnak

It is well-established that decohesions occurring at the interface of the matrix and rigid inclusions and second-phase particles are prime causes of ductile fracture initiation. It is not clear, however, how these decohesions occur. The idea that the interface bond is broken in tension is not particularly attractive when one considers the strength of such interfaces and the fact that plastic flow is not restricted under conditions of continuing flow required to initiate and propagate ductile fracture. A suggestion as to the mechanism of decohesion arises if one takes the position that, as the dislocation density increases with plastic flow and reaches some critical range of density, the phenomenon of flow can be regarded as fluidlike instead of the crystallographic motion of dislocations. As the spacing between dislocations decreases, the matrix becomes increasingly disordered in terms of loss of periodicity. At some critical degree of reduction of the periodicity, it is suggested that flow can be regarded as hydrodynamic, rather than crystallographic. Such a state has been referred to by rheologists as the "plasticized state", or the "fourth state of matter", between the liquid and solid state. A similar argument pertains qualitatively with the increase in equilibrium vacancy concentration as the temperature approaches the melting point. Taking the viewpoint that at larger strains the flow may become hydrodynamic in nature, a mechanism of decohesion is suggested. A well-known phenomenon in boundary-layer flow is that of "separation" locally of the boundary layer from the substrate.' Under certain conditions, the flow in the immediate neighborhood of the substrate becomes reversed, causing the boundary layer to separate from it. The exact condition for separation is that the velocity gradient normal to the substrate vanishes there, or It is of interest that blunt particles such as spheres and circular cylinders are most likely to give rise to separations because of unfavorable pressure distributions behind them. The source cited gives solutions for positions of separations for various geometries. In principle, such separations can also take place when metal is flowing over a "dead zone" of stagnant metal. This may explain the initiation of fracture at the elastic-plastic boundaries of plastic enclaves under a notch.

Jan 1, 1967

By AIME AIME

ON Thursday a most interesting symposium on "Gases in Metals" was held, with both morning and afternoon sessions. The morning was devoted principally to the considerations of the steel maker, the nonferrous field being taken up in the afternoon period. Dr. John Johnston, as chairman, introduced the subject with "A Short Analysis of the Gas-metal Problem and Its Practical Importance." He then introduced P. H. Brace who explained in considerable detail the various vacuum fusion and other methods in use at present, both here and abroad, in the study of "gases" in metals. He was fol¬lowed immediately by H. W. Graham on "The Effect of Oxygen in Steel." The papers elicited considerable discussion, the point being particularly noted by both Dr. Rawdon and Dr. Sauveur that a knowledge of "total oxygen" alone is not sufficient information for the metallurgist, distribution of oxygen being probably the more important. Dr. Johnston, in commenting on the lack of agreement among many of the methods now in use, such as the Ledebur and vacuum fusion, spoke of the contemplated plan of the Iron and Steel Division to have a number of standard samples analyzed by many laboratories by the various methods, the Bureau of Standards acting as a clearing house, so that more definite information may be obtained on the comparative accuracy of the method.

Jan 1, 1933

By Ernest R. Lilley

THOSE acquainted with the fundamental differences between the, educational .systems of Great Britain and. the United States would hardly expect .the training of men for the petroleum industry to proceed along the same lines- in the two countries. The youth entering an English university is, except in the case of-the student from some of the British colonies or from foreign countries, almost invariably a product of the English "public school." This is in no sense comparable .with the American public school. It is a private institution, frequently of considerable age and heavily endowed. In many aspects it seems to be comparable with the American preparatory school. Yet to some extent its activities remind one of the first years of the undergraduate: course in the American college. Certainly it takes to-itself many of the social, functions of the American college.

Jan 1, 1931

By C. L. Berrien

BEFORE the present company was formed, in 1916, each group of mines comprising the old organizations made its detailed daily and monthly mine cost records along the lines used before the consolidation; that is, there was no attempt made to standardize and compare the stope costs of all mines. The general cost sheets for all mines, however, were standardized, and cumulative labor cost sheets were compiled in the general superintendent's office. At most of the mines, a daily record or distribution sheet for each working place was kept, showing the number of men, hours of drilling, hours of timbering, hours of tramming, cars of ore, cars of waste, sticks of powder and feet of fuse. This information was kept by each shift boss and entered on the distribution sheet by him or, at some mines, by a tram boss. The superintendent solved his own problems under the direction of the general superintendent, but without coming in touch with other superintendents, either through records or general conferences. Probably 95 per cent. of the stopes were square-set worked by day's pay; there were some back-filling and shrinkage stopes. Many of the development places, such as shaft sinking, station cutting, drifting and raises had always been run by contract. These contracts were given, for no definite period, at so much per linear foot and were measured monthly, or when completed; the men being paid monthly. In some cases, fairness to the employee, was not maintained. On the whole, there was no standardization. There were no stope contracts, because of the objections of the Western Federation of Miners to general contracting in the mines.

Jan 2, 1922

By J. M. Morris

THE point to be made most clear in this paper is the economic value of flotation in the Benguet mill flow sheet. It is rather a statement of effect with no attempt at a technical explanation of the cause. Certain well-known, easily understood reagents, mechanisms and principles have been adapted to the conditions at Benguet, and have proved to be more successful than was demonstrated in the laboratory. The mechanical and metallurgical development of this particular operation was arrived at by trial and error, with fortunately very little error. Changes were slow, of necessity, which in the end proved a blessing in that time was afforded for observation and analysis of the disturbing factors; and as a result each change was a definite step towards higher efficiency. Many of these steps were unpredictable from labora-tory work because of the varied and differing characteristics of ores met with in daily operation of the mill, which were practically impossible to reproduce on a laboratory scale. The Benguet mill receives daily ores that differ as much as if they were delivered from three different properties. There is first the surface and upper-level zone, which produces an oxidized secondary ore contain-ing considerable iron oxide, manganese oxide and some organic matter. Formerly, most of this ore consisted of very soft fill with some hard rock mixed in. It also contained an unusual amount of iron and aluminum sulfate, which formed hydrates upon entering the alkaline cyanide solu-tion and caused excessive frothing. When flotation was introduced in the Benguet mill the general char-acteristics of this upper-level ore had changed considerably, in that it was practically all newly mined, fairly hard ore. It still contained many of the same disturbing elements, but was somewhat simpler to treat than formerly. The small proportion of fines is still troublesome in flotation, and plant practice probably does not show more than 80 per cent extraction on this small portion of the ore. No definite figure on this is available, as this particular ore is delivered at irregular intervals

Jan 1, 1936

By J. J. Jakosky

The strategic importance of the metallic minerals in our industrial economy, and the declining rates of discovery have focused attention on means of exploration for new mineral deposits. A consideration of exploration techniques leads to an attempt to evaluate the effectiveness of geophysics as a tool for mining exploration. One means of evaluation will be to compare the use of geophysics in petroleum exploration with its possible uses in mining. Geophysics in Petroleum Exploration During the past twenty years, the petroleum industry has established an effective exploration technique. Geology is the basic tool in those areas where reliable predictions can be made from surface conditions. In the other areas, where the geological studies are inadequate, they must be supplemented with geophysics or direct exploration, such as drilling. Since geophysical work is far less costly than any form of direct explbration, it is used almost exclusively as the means for obtaining the desired subsurface information. The geological and geophysical techniques are credited with locating sites which yielded one producer for three dry holes during the year 1947.' For the wells located without geology or geophysics, there is a ratio of one producing well to sixteen dry holes. From these figures it is seen that the geological and geophysical techniques are more than four times as successful as the nontechnical exploration. It will be in order to consider further this ratio of one producer to three dry holes. The geophysical methods in use today† do not pretend to locate oil directly; their function is to locate anomalies or structures favorable for the accumulation of oil. For a producing oil well we must have not only structure, but also other favorable conditions, namely: petroliferous source beds, the required porosity and permeability in the reservoir rocks, an impermeable cap rock over the reser- voir, and the necessary water or gravity drive to force the oil into the bore hole. Since the geophysical work can only detect and sometimes delimit the anomaly, these other necessary conditions can be determined only by direct exploration. The success of modern geophysical work in locating and limiting the structure itself is remarkably high, probably over 95 pct accurate. Geophysical work renders an important service in the delineation of the structurally unfavorable areas and their elimination from the drilling phase of the exploration program. When attempting to locate any material of scarce occurrence in the earth, it is of paramount importance to know where not to dig. This elimination of barren areas is the least appreciated but is of great economic importance. For illustration, the difference between one producer to three dry holes, and one producer to sixteen dry holes, represents a saving of thirteen drilled wells, which would require an expenditure many times the cost of the geophysical work that might have revealed the nonfavorable structural conditions. The percentage of geophysically-located wells necessarily will continue to increase in the statistics of future years, as the search for oil is extended

Jan 1, 1950

By E. S. Bardwell

TWENTY years ago, W. T. Burns, in his paper presented at the Butte Meeting of the Institute, discussed the general scheme then in use in the electrolytic copper refinery of the Anaconda Copper Mining. Co. at Great Falls, Mont., for removing impurities from tank-room electrolyte and controlling its acid content. Since then marked changes have taken place in copper-refinery practice at Great Falls. The electrolytic copper refinery in use in 1913 has been replaced by a new and entirely modern plant capable of producing up to 27,000,000 lb. of cathode copper per month. With the building of the new plant in 1916, the treatment of converter anodes was discontinued. At first the substitution of refined anodes for converter anodes resulted in a decrease in the impurity content of the anodes, but as time went on, changes in metallurgical practices at the smelter resulted in substantial increases in the impurity content of the anodes. The leaching of the silver slime to remove copper before shipment to Raritan for treatment further added to the purification problem. The fact that the scheme of purifying electrolyte which Mr. Burns described in his paper' has proved adequate for our needs under a wide variation of conditions speaks well for its essential soundness.

Jan 1, 1933

By O. C. Wheeler

There was a marked increase in the investigation of undeveloped areas in Colombia during 1936. The Shell company commenced geological and geophysical investigations on an intensive scale in the Upper Magdalena Valley and at the end of the year had several geological and geophysical parties working in that area. These investigations were supplemented by aerial photography and it is understood that negotiations are under way for having this work continued. The Shell is reported to have acquired some options and leases on private properties in the Upper Valley region and in the western part of Cundinamarca. The Socony Vacuum was making preparations to begin seismograph work on its property north of the Sogamoso River, acquired in 1934 from Sefior Luciano Restrepo. This company will probably start drilling on the property during 1937. The Richmond Petroleum Co. (Standard of California) is said to have renewed geological investigations in the Upper Magdalena Valley above Honda. Local Colombian interests took an active part in applying for concessions on nationally owned lands in the area between the Carare and Magdalena Rivers. The application of the Sociedad National del Carare for a concession in this area was granted during the year. Subsequently an agreement was reached between this

Jan 1, 1937

By John D. Gill

THIS paper assumes the incontrovertible nature of the statement that the validity of competition in the nonnatural resource industries is established firmly on the rate and extent of the economic development of the United States. It then demonstrates the nonexistence of any condition within the petroleum industry that would invalidate the principle of competition as applied to it. It points to the benefits that competition has effected in the oil industry and the reasons why the practice of the competitive principle should continue to keep the industry virile and progressive in meeting the requirements of future generations for the kind of products natural to it. Finally, it pleads for a clearer view of the affairs of the oil industry by seeing them against a background of the whole economy. INTRODUCTION Even a few years ago there would have been only an academic reason for presenting before this Institute a paper on the validity of competition in the oil industry or any other natural resource industry; today there is no more practical subject for this body to consider. In social importance it transcends attempted solutions of perplexing technical problems; and even the numerous legal and economic problems that grow out of administration of state regulatory measures appear to be of secondary importance because they would cease to exist if competition were abolished. The aspiration of certain elements of the Federal Government to acquire control of the oil industry has long been suspected The vital need for petroleum in the national defense ... confirms my belief in the urgent need of Federal legislation to safeguard our petroleum supply through prevention of waste and by establishment and maintenance of sound economic conditions in the oil industry... . But also it may be dismissed with this mere mention of it because it predicates government control and the abandonment or broad reduction of competition on a war emergency. Clearly, the fight for a nation's life may justify a government's control over men and resources that would be abhorrent and economically enervating under conditions of national security. More pertinent to the present matter, because it appears expressive neither of a personal ambition nor of an emergency condition but rather of the long-range view of a certain school of conservationists, is the pronouncement of no less an authority than the Attorney General of the United States, who has been repeatedly quoted by the press as saying that the American Petroleum Industry constituted a case "where the principle of conservation of an exhaustible and irreplaceable resource should replace the principle of competitive exploitation." The significance of this statement in the light of the commonly accepted meanings of the " principle of conservation" and of the "principle of competitive ex-

Jan 1, 1941

By R. K. Agarwal

Transforming from a mere novelty field of science to a well-recognized branch of engineering, the scientific discipline of rock mechanics continues to mature. The past decade has witnessed an unprecedented in- fusion of scientific research approach into mine design. In the preceding year alone, there were six national and international congresses which also indicated the increased interest, in rock mechanics and participation by scientific personnel with diversified backgrounds. It may be presumptuous to conclude that the time, effort and money spent thus far on procedures for mine structure design have necessarily resulted in the evolvement of design techniques; but certainly the prospects of evolving such techniques art: more promising at present than ever before.

Jan 1, 1970

By Paul Weir

PRODUCTION METHODS in the bituminous coal mines in the United States are undergoing many changes. Although the primary object of these changes is the production of a better product at a cheaper cost there are other considerations such as the improvement of conditions under which miners live and work. The almost complete unionization of the manual workers in the industry during the past four years has 'brought with it a stabilization of wages on a relatively high basis and of hours of work per day and per week on a relatively low basis. With differentials in wages between producing districts firmly established, and with a nation- wide and uniform application of in-

Jan 1, 1937

By D. Kelly Campbell

Cleveland-Cliffs Conveyor System Uses Twisted Belt To: 1 -Beat Upper Peninsula Weather 2- Solve Underground Transportation Problems

Jan 7, 1953

WITH the present mobilization program in full swing and the enrollment in engineering colleges dropping off, many solutions are offered to relieve the shortage of trained men in the engineering profession. Industry can absorb about 30,000 engineers annually, according to the Engineers Joint Council, and forecasts indicate that the number graduating will have dropped from 38,000 in 1951 to about 12,000 in 1954. If this condition were to continue there would probably not be enough people with technical training to run industry in four or five years.

Jan 12, 1951

Mr. Raden has described the practical problems associated with fines in phosphate rock beneficiation. In this discussion, a colloid chemical viewpoint is given to the problem of separating phosphate values from phosphatic clay slurries. The phosphatic clays are predominantly colloids of a complex mixture of many minerals (1). The constituents are typically 25% apatite, 40-50% clays, and various amounts of wavellite, quartz, dolomite, fluorite, and other minerals. The clays are montmorillonite, attapulgite, and illite, with some kaolinite. The various mineral colloids in the slurry are heterogeneously coagulated in the as-produced state. Dispersion of the coagulated state is evident from the fact that dispersing agents (certain polyelectrolytes) cause a large reduction in the viscosity of the slurry (2). The as-produced slurry settles from 4 to 8% solids within a week, but thereafter settles much more slowly in the form of a sediment of flocs. The supernatant liquid is often clear because of the cooperative action of the mutual interaction of particles during settling. Mineral segregation during settling has not been observed for the same reason. The initial slow settling rates indicate that the coagulated assemblies are very small. Efforts to separate apatite from the other minerals would be complicated by the heterogeneous coagulation state. Somehow the apatite must be "liberated" from its association with the other minerals before it can be physically separated. One approach for liberating apatite is to disperse the entire suspension. While this is feasible technically, for example by using certain polyelectrolytes (2), the reagent costs based on present

Jan 1, 1979

By H. E. Kramm

(New York Meeting, February, 1919.) DURING the summer of 1911, I had the opportunity to study in detail the geological conditions of what is known in northern California as " Harrison gulch," in Shasta county. Though the district, as a whole, that is, the western part of Shasta and the eastern part of Trinity county, has contributed during the last 15 years a considerable share of the gold-production credited to Shasta county, very little is known of its geology, perhaps because the country is covered with a dense growth of brush which makes exploration and prospecting extremely difficult. Topographically the district presents a succession of ridges trending approximately N-S.; and alternating with deep narrow canyons. The drainage is partly into . the Sacramento, partly into the Trinity river. Climatic conditions in summer time are almost ideal. It is true, the thermometer may climb to 115°, but the air is dry and the heat is bearable, especially as the nights are always cool. It seldom rains during the summer months, and creeks and springs dry out towards the end of the summer. The winter is severe, lasting from November to April, and usually a thick layer of snow covers the mountains. By reason of the character of its gold-deposits, the region is known to miners as "the pocket country." It contains a series ?of eruptive rocks intruded into slates, cherts, limestones, and conglomerates. Dikes, laccoliths, and batholiths are frequent. In a day's ride it is possible to find all the common igneous rocks from the very acid to the very basic. Serpentines are especially abundant.. The sedimentary rocks are, as rule, broken and shattered as well as folded, and show the effects of intense metamorphism. ? Pocket-hunters " speak of the contact of diabase and slate as the ? pocket-contact." Some rich gold-pockets, however, have also been found in the diabase.

Jul 1, 1912

By William Hilliard

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

Jan 1, 1932

By J. William Fehnel

The health hazard due to the inhalation of certain dusts in the mining industry has been recognized, but was not subject to state or federal inquiry in the United States until about 1916. Reports on miners' phthisis and associated effect of dust inhalation were published as early as 1903 in South Africa and in 1906 in Australia. A report was made by Lanzal in January 1917 of a study of 433 cases of miners' consumption among zinc miners in southwestern Missouri. In a preliminary report issued in 1915 Lanza and Higgins2 concluded that, while there were general causes, such as housing and working conditions, that tended to produce a high incidence of tuberculosis, the flint dust constituted an unusual element of danger, to which it was reasonable to attribute the unusual prevalence of tuberculosis. Later a clinic established under the joint sponsorship of the United States Bureau of Mines, the mine owners, and the Metropolitan Life Insurance Co. carried on an extensive study covering a period of five years. The results of this study have borne out the conclusions reached in the earlier surveys. The early surveys in this country indicated the necessity of determining the extent of the dust pollution of air associated with the various mining operations. The first determinations were reported on the weight basis, undoubtedly to make comparisons with work previously done in Australia. Later studies of dust in industry led to the development of more refined methods of sampling and enumeration on the basis of count in place of weight, so that by 1919 Knowles3 reported 53 methods.

Jan 1, 1937

By Donald W. Gentry

The recently established SME-AIME Education Board has completed its first full year of operation, and its six constituent committees-Accreditation, Career Guidance, Continuing Education, Educational Statistics, and Scholarship-have been extremely active in identifying and initiating programs to serve the educational needs of the Society of Mining Engineers and its members. The Continuing Education Committee-primarily concerned with the needs and problems associated with providing a continuing education program for SME members-is responsible for: (1) determining the need for short course offerings; (2) developing needed courses, along with new means and opportunities of presentation; and (3) scheduling and evaluating course presentation. In response to this charge, the committee has sponsored two short courses at the SME-AIME Fall Meeting in St. Louis and three short courses at the AIME Annual Meeting in Denver. Its major effort, however, has been directed toward the 1978 SME-AIME Fall Meeting to be held in Orlando, Fla., where 18 days of short-course instruction have been scheduled. A portion of these courses will be presented prior to the meeting, with the remainder to be presented in Nassau, Bahamas, immediately following the meeting.

Jan 7, 1978