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Jan 1, 1913

Jan 1, 1912

By T. W. Healy, M. S. Moignard

The use of electrokinetic or zeta-potential phenomena in studies of the properties of mineral sulphides has increased greatly over recent years. This review aims to examine and discuss the body of literature on the subject of electrokinetic properties of sulphides in a comprehensive and critical manner. Although the review covers the period from 1925 to 1975, it is only in the past ten years that researchers have been fully aware of the implications and problems of chemical reactions, notably oxidation and precipitation reactions, on the surface properties of sulphide minerals. These papers are discussed in more detail than the earlier publications. A table containing a list of determinations of iso-electric- points and points-of-zero-charge of mineral sulphides, and the methods employed in obtaining these results, is presented.

Jan 1, 1976

Jan 1, 1961

By Joseph B. Darby, Paul A. Beck

IN isothermal sections of several ternary systems, the a-phase was found1 to extend in the form of a relatively narrow elongated field, connecting the U-phases that are present in the adjoining binary systems. This was interpreted in accordance with the conception that the U-phase is an electron compound and the ternary U-phase fields were shown in several systems' to extend approximately in the direction of constant average d-shell electron vacancy number per atom. ' However, in the various isothermal sections of the Fe-Cr-Mo system" the ternary a-phase field was

Jan 1, 1958

By Arthur Zentner

The electrolytic zinc plant of today is foreshadowed in the patents issued to Léon Létrange of Paris in 1881 and 1883l. He proposed roasting zinc blende to make the zinc soluble in water or sulphuric acid, thus obtaining a sulphate solution. His purification was apparently that used in the lithopone work of the day. For electrolyzing he proposed anodes of carbon or lead, for cathodes zinc, copper or brass. Numerous patents by other workers were taken out in the first 10 years, most of which dealt with sulphate solutions. It is easy to presume that the formation of chlorine gas in zinc chloride electrolysis caused early emphasis on sulphate work. Lack of success with this invited further work with chloride solutions. Efficient and cheaper oxidizing agents for use in the chloride processes were more generally available. Carbon anodes could be used instead of lead anodes, which were blamed for much of the early electrolyzing troubles and remained in disfavor for many years. Carl Hoepfner received his first zinc patents in 18902. He was the most persistent of those who worked with chloride solutions and met with the largest measure of success. Hc built three plants, only one of which remained in operation. This was built in 1896 at the plant of Brunner, Mond & Co., Winnington, England, now part of Imperial Chemical Industries Ltd. It leached with by-product calcium chloride from the company's Solvay alkali plant and returned to it the chlorine formed in electrolyzing. The zinc plant had a capacity of 5 long tons of zinc, said to have been doubled later, and remained in operation until 1924. No commercial plant using chloride solutions has operated since then. E. A. Ashcroft experimented in the middle nineties with chloride, alkaline and sulphate solutions on materials from Broken Hill, Australia. He built a plant with a rated capacity of 10 long tons of zinc per day, at Cockle Creek, New South Wales, in 1898. This figure was never approached nor was cyclical operation achieved. The work in the plant appears to have been largely with sulphate solutions. The plant suffered from a multitude of troubles: poor roasting, gclatinous silica, liberal use of live steam in solutions to combat the gclatinous silica with considerable

Jan 1, 1937

By John V. Beall

Homeland of the Republic of China, the island of Taiwan looks on the map like a seal, muzzle pointed south, resting complacently on the emerald waters of the China Sea. Any notion of placidness is quickly dispelled by going to that country where the visitor gains the impression of almost violent busyness in tearing up streets, pushing up buildings and tilling the fields. Driving from the airport downtown to Taipei, the capital city, one sees roads, streets and thorough-fares which seethe with bizarre traffic. From water buffaloes to buses, transportation takes every conceivable shape, size and color in between. The load being transported need not conform in any way to the capabilities of the vehicle. Twenty- foot lengths of pipe may be trans- ported on a bicycle. A family of five may go to town on a motor- cycle. Impossible? Count them. The streets and buildings of the city appear unrestrained, or without margins. Shops do not end at the doorway but overflow with a variety of goods onto the sidewalks and into the streets where the marginal traffic, on foot or on wheels, intertwines unconcernedly with the flotsam from the shops. Signs, dry goods, hardware and the continuous hubbub make the view colorful, lighthearted and fascinating. The island is 230 miles long by 75 miles wide with a central mountain spine. To the east, the mountains descend steeply to the ocean whereas to the west, beyond the foothills, there is a broad coastal plain. Only about 25% of the land is suitable for cultivation but the tropical climate permits several harvests a year. At the same time the mountains, which are high enough to sometimes have snow, offer an agreeable change of temperature. In this setting, society has created an economy that is growing at such a rate on all fronts that it would seem to be fairly bursting at the seams.

Jan 9, 1969

Jan 1, 1891

By E. Kendall Cork

The traditional financial objective for a single mine company has been to operate as frugally as possible and to pay out most of the earnings as dividends. If the business is cyclical (as it is for most metals) the dividends might fluctuate quite widely. When the mine is exhausted the company disappears. This is still quite a viable strategy for a single mine company. It is not however a viable strategy for the world as a whole. The mining industry is built by mine development companies who can mobilize the people and capital to bring new mines into production. Their skills must include marketing, engineering, finance and other politics. It is very rare for a property to be brought in without the support of a major company that can provide all these services. The exceptions will usually have some other form of big brother support, for example the U.S. government uranium contracts at guaranteed generous prices. The mine development company will seek as a minimum to perpetuate itself by developing new mines in order to replace those which are running out. The more common and more ambitious objective is to grow -- that is to add to its ore reserves and current production by developing more new mines. The financial objectives for that company are very different. Obviously if all the earnings were paid out in dividends there would be nothing left to work with. The first financial policy then is to spend an appropriate amount on exploration for new properties. The next is to retain enough of the earnings to provide the capital for new projects at least sufficient for the equity. There is no magic formula as to what proportion of earnings should properly be distributed as dividends by a growth-oriented mine development company. As a rough rule of thumb distributing half or more will probably leave too little to work on and 30% or so is probably a good balance. However the circumstances differ widely from company to company. It may be useful to set an objective for the rate of growth of a company's earnings. Some have picked rates such as 15% per annum compounded. Others have set a target in real terms which might appear as 10 or 11% plus inflation. Obviously the arithmetic of compound interest is very attractive; however in practice there is much variation. Indeed current returns from existing operations swing widely with the business cycle and there is no assurance that economic new properties will be found according to someone's arbitrary time schedule. For example, Western Mining Corporation Limited in Australia explored for 30 years with little to show for it, but then found the great Australian nickel deposits and more recently the huge Roxby Downs copper. That long dry spell could not have fitted anyone's arbitrary calendar of growth and yet they would not have found such orebodies without that long period of effort. Should they have abandoned the search? Once a new property has been found or acquired there has to be a threshold rate of return on the new capital to be invested against which to evaluate the property's economics. Conventionally this seems to be 15% after tax, a number common in other heavy industries as well. In some cases it is expressed as a lower number plus allowance for inflation. Discounted cash flow analysis is a very useful tool but it does not make the decision. In the end a "go" decision depends on judgment of many factors some of which are numbers used in the DCF calculation whose credibility must be examined. It is curious how frequently investment proposals come in with the rates of return very close to 15%. The project advocates know that a number much less than 15% will not fly and that a number much more is not necessary. With much higher nominal and real interest rates of recent years, even though before tax, logic suggests that the hurdle rate should also rise. The power of compound interest is so great that 20% is very hard to achieve in any cash flow projection but 18% may be a sensible yard - stick. Once again it is remarkable how many project proposals come in with an 18% return. On the record the mining industry as a whole has not been overly restrictive in choosing its hurdle rates of return. This is shown by the abundance of metals in recent years and the failure of metal prices to keep up with inflation. All of the foregoing is standard text book stuff.

Jan 1, 1985

By C. A. Heiland

THERE once was a little kid, whose lot was a very tough one until he grew up. His parents did not have much in common; from all indica-tions, it is probable that the child was not wanted. His father Geology and his mother Physics separated shortly after his birth, which occurred during the World War amid a smoke screen of mathematics. He was kicked around a great deal. His parents could not agree on a name, and they finally christened him "Geophysics," for short. His relatives insisted that the name should be "Geophysical Prospecting," "Geophys-ical Exploration" or "Exploratory Geophysics"; though the youngster has grown up by now, this battle is still going on. His father did not think the child would amount to much until he began to show some unexpected talents, which were acquired, no doubt, from his mother Physics. His progress caused his father no little worry, and he began to wonder whether his offspring would help him in his business when he grew up or would set up shop in competition with the old man. His aunt Petroleum watched his growth with benevolent interest; his uncle Mining remained rather skeptical and cousin Civil Engineering not only assumed the attitude of the man from Missouri but was not much con-vinced even after he had been shown. Making a long story short, the kid decided that he had to stand on his own feet and get along as best he could. Having come from a good family . he possessed some outstanding characteristics such as resourcefulness and a reasonable amount of business ability. He therefore decided that it would be to his advantage to follow in his father's and mother's foot-steps as much as possible, and develop the good qualities of both. As a result, the youngster did fairly well for himself, and his relatives decided that it might be to their advantage to be on better terms with him. Father Geology had come to the conclusion that the boy could be very helpful to him and now wanted him to live in his house. His mother, who had brought him through the teething and measles stages, felt quite capable of bringing up the boy without the help of his father; and, as the fairer sex will do, would confide to a neighbor every now and then that his

Jan 1, 1938

By John Fulton

THE increase in the production of iron has been accompanied by a growing demand for an improved quality, and more especially at the present time, in the manufacture of Bessemer steel, which is rapidly becoming an important branch of industry. This has led the makers of pig iron to a careful investigation of the composition of the materials from which their metal is produced, the inquiry being greatly assisted by a cordial alliance of science and practice. Formerly, chemical science was held in abeyance, or admitted in a hesitating experimental way ; but now it is received as a valuable auxiliary, and its decisions are accepted as final and conclusive. It is called on to assist the iron-maker in determining the quality of his stock, and to detect the presence of injurious elements in his fuel, ores, flux, or iron. The object of this paper is to submit the method now in use at the furnaces of the Kemble Coal and Iron Company in the Broad Top coal and iron region, for removing, by a process of crushing and washing, slate and other impurities from coal, designed, when coked, for furnace fuel. It is not contemplated to claim very advanced progress in this work, believing that it is susceptible of improvement, but to show that some progress has been made in a comparatively new field, and it is hoped in the right direction, since coke is probably destined to become the principal fuel in the metallurgy of iron. The Broad Top coal region occupies an isolated geographical position, standing 25 miles east from the Alleghany field. It is associated with the latter by the structure of its coal, and more closely with the Cumberland field by a similarity in the quality of coal.

By R. B. Moffitt

INTRODUCTION In recent times the continuing depletion of high grade mineral deposits and the massive increase in raw material consumption have forced the metal mining industry to exploit ore bodies of lower and lower grades. To obtain a satisfactory financial return from these deposits, there has been the concurrent and evident trend towards increasing the size of operations to obtain benefits from the economies of scale. The evaluation, planning, and design of these large scale open-pit operations, so as to yield the maximum possible return on investment, is an extremely complex, iterative procedure. With profit margins trimmed, "small" errors can become much more significant and with exploration costs spiralling, accurate and rapid evaluation is essential. It demands a sophistication and precision in the evaluation process unheard of ten years ago. What follows attempts to describe the need to thoroughly plan the overall evaluation programme such that duplication of effort is avoided and all relevant information is systematically recorded from the outset of exploration. The final section of the paper takes a realistic case study to illustrate the significance of pit slope angles on the design of the final pit and the economics of the total project. THE EVALUATION PROGRAMME The team, (for a team effort it must be), that is charged with the responsibility of conducting the evaluation exercise, has the difficult task of placing values on a multitude of independent and inter-related variables. Each variable has some economic significance; the degree of significance varying according to the metal sought, the environment in which it occurs, the vagaries of the market place, to name but a few of the problems facing the project team. From this maze of variables, the team must identify those that have the most critical influence on the overall economics of the proposed venture. Investigations must then be set in motion to quantify these controlling factors more precisely. It is important to recognize that such investigations form part of the evaluation programme and require monitoring for both timing and cost as the whole exercise of evaluating the project continues. To add to the difficulties, the economic significance of any particular variable may change during the course of the programme.

Jan 1, 1972

By H. l. Burghoff, D. E. Lawson

The presence of tellurium in copper and, by inference, in copper alloys, has been considered seriously detrimental and has been avoided. In particular, very small amounts of tellurium have been found to produce red-shortness, although the effects on cold-working and ordinary physical and mechanical properties have not been known so definitely. References in the literature are few, but as long ago as 1881, Eglestonl reported that 0.083 per cent tellurium in fire-refined copper rendered the copper red-short and therefore worthless for hot-rolling. In hot-rolling copper cakes containing this amount of tellurium, he found that fine cracks appeared in the cakes on the first pass through the rolls, the cracks opening further in successive passes. When cold, the metal was said to be tough and malleable. A few years ago, during the course of an investigation in our laboratory on copper-base alloys, it was found that tellurium-bearing alloys could be machined much more freely than similar alloys not containing tellurium. The study was pursued further in this direction, and considerable data were obtained, which indicated that certain tellurium-bearing alloys might have properties of commercial interest. The work eventually led to patent protection,2 a wide range of tellurium-bearing copper-base alloys being covered. This article presents results obtained on the effect of tellurium on the mechanical properties of three copper-base alloys: commercial bronze (90 Cu, 10 Zn), 1.5 per cent tin bronze (98.5 Cu, 1.5 Sn), and silicon bronze (96 Cu, 3Si, 1 Zn). Several alloys were cast in each series, with tellurium content ranging from 0 up to about 1 per cent. The alloys were melted under charcoal in a clay-graphite crucible, using a high-frequency induction furnace, and were cast without undue difficulty in rod form, 15/8 in. in diameter. Charges for the zinc and tin series were made up from the following materials: cathode copper, electrolytic zinc, tin, and tellurium in slab

Jan 1, 1938

By C. A. Eligwe, F. W. DeVries, A. E. Torma

This study is an investigation on using hydrogen peroxide for tank-leaching of uranium with sulfuric acid. The optimum sulfuric acid concentration was found to be 0.03 mole 11 -'for a 25% pulp density suspension. The order of reaction with respect to sulfuric acid concentration was found to be ns0.75. The best results vith hydrogen peroxide were obtained at a 4.64 molar ratio of 6202 to U in the ore. The order of reaction was found to be zero with respect to hydrogen peroxide concentration. The theoretical maximum rate effect of Hz02 on uranium extraction was derived as Vm = 8.15 x mole &-'min-'. The highest rate experimentally attained was 8.09 x mole kL'min-'. It was found that the uranium extrac- tion was not affected by the pulp density up to the 50% used in this study. However, the final yieldswere significantly higher (over 90%) for leaches carried out in the presence of Hz02 than (less than 90%) for leaches carried out in the absence of H202. The reaction was found to follow a first order course with respect to substrate concentration (pulp density) regardless of the presence of H202. The effect of temperature was more explicit at moderate tempetatures (30 to 55 C) than at lower (10 C) or at higher (70 C) temperatures. At this latter temperature an almost complete extraction was realized even without H202. The apparent activation energies were found to be AEa = 2.68 kJ mole-' in the absence of H202, 0.5 kJ mole-'with Hz02 at 40 C to 70 C. and 4.72 kJ mole-' with Hz02 at 10 C to 40 C. All these activation energy values suggested that the uranium extraction process is diffusion controlled regardless of the presence of H202. Further, the change in activation energy in the presence of Hz02 indicates the possibility of change in the reaction mechanisms at lower and higher temperatures.

Jan 1, 1980

By H. l. Burghoff, D. E. Lawson

The presence of tellurium in copper and, by inference, in copper alloys, has been considered seriously detrimental and has been avoided. In particular, very small amounts of tellurium have been found to produce red-shortness, although the effects on cold-working and ordinary physical and mechanical properties have not been known so definitely. References in the literature are few, but as long ago as 1881, Eglestonl reported that 0.083 per cent tellurium in fire-refined copper rendered the copper red-short and therefore worthless for hot-rolling. In hot-rolling copper cakes containing this amount of tellurium, he found that fine cracks appeared in the cakes on the first pass through the rolls, the cracks opening further in successive passes. When cold, the metal was said to be tough and malleable. A few years ago, during the course of an investigation in our laboratory on copper-base alloys, it was found that tellurium-bearing alloys could be machined much more freely than similar alloys not containing tellurium. The study was pursued further in this direction, and considerable data were obtained, which indicated that certain tellurium-bearing alloys might have properties of commercial interest. The work eventually led to patent protection,2 a wide range of tellurium-bearing copper-base alloys being covered. This article presents results obtained on the effect of tellurium on the mechanical properties of three copper-base alloys: commercial bronze (90 Cu, 10 Zn), 1.5 per cent tin bronze (98.5 Cu, 1.5 Sn), and silicon bronze (96 Cu, 3Si, 1 Zn). Several alloys were cast in each series, with tellurium content ranging from 0 up to about 1 per cent. The alloys were melted under charcoal in a clay-graphite crucible, using a high-frequency induction furnace, and were cast without undue difficulty in rod form, 15/8 in. in diameter. Charges for the zinc and tin series were made up from the following materials: cathode copper, electrolytic zinc, tin, and tellurium in slab

Jan 1, 1938

By J. W. Littleford

The Roan Antelope Copper Mines Ltd. are situated in the north central part of Northern Rhodesia, at an altitude of 4000 ft. and 13" south of the Equator. The town site (Luanshya) is well situated and enjoys among other things a really temperate climate for 10 months of the year. The two spring and summer months, October and November, while hot and humid, do not bring any great discomforts as compared with many other mining camps. Strictly modern brick homes, with electric lights, purified water, telephone and water-borne sewage, add to the comfort of the employees. A rainfall of approximately 60 in. per year furnishes ample water for both industrial and domestic purposes. The rainy season generally begins in October and lasts through until March. As much as 3 to 4 in. is recorded in 24 hr., but this offers no difficulties because the runoff is very rapid. The property is connected by a 24-mile branch line from Ndola with the main line of the Beira-Mashonaland and Rhodesia Railways Ltd. Practically all supplies from overseas are transported over this line from Beira, 1743 miles distant on the east coast in Portuguese East Africa. The mine output also leaves Africa from this port. Passenger service is principally via Cape Town or Durban, a distance of about 2100 miles to either port. The Imperial Airways maintain a service from Cape Town to Croydon, taking 9 days for the trip. Connections can be made with this service at Broken Hill, 150 miles south of Luanshya, by either rail or automobile. Thus, after several days of travel through virgin bush, a visitor arrives at a typically modern town site in the heart of Africa. Every development in mining, milling and smelting practice is used to advantage. Plan of Mill The practice in the three principal phases of the production of copper from the ores of this company have been published from time to time. Milling practice, however, is continually changing and what may be

Jan 1, 1935

By R. W. Raymond

THE question, what is the best proportion among weight, fall, and speed of stamps, is one which has not yet received thorough and systematic examination. In considering the economical application of stamping machinery, we meet, at the beginning, with serious difficulties in obtaining accurate data for comparison. The weight and fall of stamps vary as the shoes and dies wear out; and this may lead to a change of speed also. Moreover, defects in engines, boilers, or machinery for the transmission of power, may occasion serious losses, which cannot fairly be charged to the arrangements of the stamps proper. Again, the capacity of stamp-mills is directly dependent, in some degree, upon the nature and extent of discharge, fineness of screens, and other peculiarities of the battery. Finally, the hardness and tenacity of the rock crushed varies so much that comparisons between different localities cannot be implicitly trusted. The safest experiments are those made in the same mill, by changing first one and then another condition of working; but this is seldom possible for such conditions as weight and lift of stamps, and only within narrow limits for their speed. We may eliminate questions of friction, transmission, and generation of power, in the case of stamps, by measuring the power actually developed by their fall. Thus, the weight, multiplied into the fall in feet, and the number of drops per minute, gives us exactly the number of foot-pounds exerted by each stamp. Dividing by 33,000, the number of foot-pounds per minute in one-horse power, we have the horse-power per stamp, from which the effective power of the whole mill may be obtained. Dividing the amount of rock crushed daily by the effective horse-power, gives us the daily amount per horse-power; and this is the best measure that can be obtained for the effectiveness of the stamps. A complete discussion of the subject would require us to determine the exact influence of the discharge, etc., and the exact resistance offered by different classes of rocks, for both of which points the data are wanting. Professor J. D. Hague, in the third volume of the United States Geological Exploration of the Fortieth Parallel, gives a valuable

Jan 1, 1873

By R. W. Raymond

The death of the eldest of the honorary members of the Institute was not unexpected. Ritter von Tunner had never recovered from the effects of a paralytic stroke received in 1892, and when the same enemy struck again in February of this year the blow was plainly mortal. He passed away June 9th, gently and without pain. Thus ends a career of great distinction and fruitfulness, crowned with fame and love. This pioneer of the age of iron and steel had lived so long and wrought so much that the present generation could scarcely recall the whole category of his services. There can be no more appropriate use of the pages of these Transactions than to honor them with a record of such a life and work, for the inspiration of other lives to other labors. Peter Tunner was born May 10, 1809, near Peggau, in Styria.† In the same province, his grandfather, Josef Tunner, had purchased a primitive nail-forge and enlarged it to a ham

Jan 1, 1898

By Edward Keller

In order to conduct intelligently the sampling of copper of various forms and grades, solid or in molten furnace-charges, a knowledge of this subject is essential. Yet figures and tests have been persistently withheld from publication, and the books at our command give us little or no information in this regard. This gap in our copper-literature has led to a series of experiments, the results of which are given below. Nearly all gold- and silver-bearing copper, destined for shipment, is cast into the form of bars or pigs. For the sampler, the question arises, Does copper, so cast, remain homogeneous ? If it does, sampling should present no difficulties; but, from experience, we know that this is not the case, and we are thus led to study the behavior of the precious metals arid impurities in copper when the latter changes from the molten to the solid state. For the purpose of the experiments here described, all available grades of copper were selected, and all of them mere subjected to the same conditions, an important requisite for proper comparison. The molten copper obtained directly from reverberatory- and blast-furnaces was cast in a cast-iron mould, the sides and bottom of which were 1 inch thick, and would, therefore, give the copper a fair length of time to chill. The inside dimensions of the mould, and, consequently, of the block of copper obtained, were: length, 10 inches; width, 9 inches; and depth, 5 inches. Fig. 1 illustrates the method employed to obtain samples from these blocks. A was cut away, and the face so produced BALTIMORE COPPER WORKS,

Jan 1, 1898

By Frank Somogyi, Donald H. Gray

Techniques for in-situ dewatering of tailings and slimes include evaporation, decantation, drainage under self weight, drainage by surcharging, and electro-osmosis. A promising technique for increasing drainage efficiency is a vertical, wall-drain system, which can be constructed in an impoundment concurrently with deposition of slurried tailings. The vertical drains, which can be constructed from sand or from the coarse fraction of a tailings stream, greatly speed the rate of consolidation of the fine tailings or slimes. The performance of a wall drain system and the semitidy of consolidation efficiency to certain variables or system parameters are examined. These parameters include the slime deposition rate, ratio of drain to slime permeability, drain width, and drain spacing.

Jan 1, 1979