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By Victor R. Cabrera

Expansion of Marcona Mining Co.'s operations in Peru several years ago increased the number of laborors and the variety of required jobs at the Company's facilities. This change made the former wage administration outdated, becoming evident by the increase of inequity grievances which threatened tile Company's good labor relations. Such a situation led Marcona to design a new wage plan based on a thorough job evaluation of all its laborer positions. The iron ore deposits, 15 miles inland from the ports of San Juan and San Nicolas, Peru, supply ore to steelmakers in the U.S., Europe and Japan. Marcona Mining Co. operates the mines under a long-term lease agreement with Peru.

Jan 7, 1964

By Alan B. Nicol, W. T. Parry

The outcome of these tests has been twofold. They have served to demonstrate that the tiltmeter is a useful and dependable instrument which could prove to be of significant value in reaching the goals of landslide prediction and control, and they have raised a good many more questions about the mechanism of slides than they have answered. It seems likely that many of the old concepts and assumptions will be modified or discarded as more knowledge of actual field phenomenon is gained. Safety and economy are paramount concerns in determining slope stability. These two considerations govern the feasibility and character of slope construction from start to finish.

Jan 1, 1970

By S. F. Ravitz

IN his excellent book on the Principles of Flotation, Wark' makes the following significant statement concerning the theory of flotation: Two questions of first-rate importance must be considered . . . First, it must be decided whether the sulfide minerals require a collector in order that they may float, or whether as has been claimed, they possess an inherent floatability and need no collector. Second, it must be decided whether the xanthate type of collector can react with or be adsorbed by the unchanged sulfide minerals themselves, or whether, as many claim, reaction with the collector is dependent upon initial oxidation of the mineral surface. In the theory of flotation there are no two questions of greater importance than these. Ravitz and Porter' presented evidence that galena can be floated without a collector, and even without any reagent, provided oxidation products are thoroughly removed from its surface. They found also that thoroughly cleaned galena floated faster when xanthate was used than when a frother alone or no reagent was used, and that, without a collector, the recovery decreased gradually upon exposure of the mineral to air. Their work, however, has met with considerable criticism. I(127).3-6 This paper is presented to answer the objections that have been raised, and to present additional data that confirm their results. EXPERIMENTAL PROCEDURE The apparatus used to provide oxygen-free conditions for flotation has been described in detail by Ravitz and Porter. An atmosphere of purified nitrogen was maintained within the apparatus; all water and solutions used were freed of dissolved air, and could be transferred where desired by the use of nitrogen pressure; nitrogen was used as the gaseous medium for flotation. The flotation cell was essentially a glass cylinder 15 cm. long and 4.6 cm. in diameter. Near the bottom was sealed a fritted glass filter, which broke up the gas into small bubbles, and 6 cm. above this filter was a side arm through which the froth overflowed. The pulp was agitated by a glass impeller, which entered the cell through a mercury seal. For each test 17 grams of galena and 75 ml. of water were placed in the cell, after which the speed of the impeller and the rate of gas flow were adjusted. Water was added gradually during the test to keep the froth level at the proper height. The mineral was prepared and cleaned in the following manner. Exceptionally pure galena was crushed by hand on a clean bucking board, screened to - 150+ 200 mesh, and deslimed on a zoo-mesh sieve with a fine spray of water. It was then boiled on a hot plate for a number of hours with several changes of the desired cleaning solution, after which both the solution and the mineral were placed in the "mineral flask" of the apparatus. The cleaning solution was drained off, and the mineral was boiled with oxygen-free water

Jan 1, 1940

By George A. Lamb

Forecasters, in estimating long-term energy requirements and supplies, have predicted a bright outlook for coal. Some predictions have annual coal output reaching 800 million tons by 1980, almost twice the average of the last five years. These projections assume that ultimate consumer energy products will be supplied adequately not only in volume but also by kind and type. The consumer energy schedule shifts continually as it reflects the changing demands for numerous uses. Its appearance, expressed generally in proportions of solids, liquids, gases and electricity, is quite different today from what it was in 1940. It may change even more by 1980. Thus, the shares that coal and the other energy sources will have In total supply will depend upon how well each source can be processed into products that will be accepted by consumers.

Jan 7, 1963

By Wayne S. Cavender

During the past year, geochemical prospecting appears to have come of age as an exploration method, and its acceptance by the mining industry is widespread. There is a growing recognition that applied geochemistry is a scientific tool and must be performed and interpreted by scientific personnel who are trained in its utilization. At present, most personnel training is done by geochemical departments in government organizations and industry groups. Most schools in the United States and Canada do not offer geochemical training, particularly at graduate levels, due to faculty limitations, lack of budgetary support and the erroneous impression that applied geochemistry is not sufficiently academic. As a result, some companies have found it expedient to send selected personnel to European schools for advanced training. A critical personnel shortage now exists will probably continue into the near future. Indications are that the rate of development of new geochemical techniques has levelled off, and the probability of new breakthroughs is not high. Present research is essentially limited to efforts by government agencies and a few private companies. Progress has been the most rapid in the development of analytical techniques, but the need remains for investigation into sampling technology and the development of more quantitative methods for the interpretation of geochemical results. Geochemists need a better understanding of the numerous physical and chemical factors which affect and control primary and secondary dispersion phenomena in all geologic environments. Detailed studies must be made of the relationship between geologic, geochemical and geophysical factors. With better interpretive techniques, the return on the geochemical exploration dollar will increase.

Jan 2, 1968

By J. J. Rutledge

THE United States Bureau of Mines established at Bruceton, Pa., in 1909, an experimental mine, for the purpose of testing the means of preventing and limiting mine explosions. During the last ten years numerous explosions have been caused to originate in .this mine for investigative purposes and the rate of propagation of the explosion wave, the pressure developed per unit of area by the explosions, and, the general results of the explosions have been carefully recorded and. studied. Means of preventing mine explosions or of limiting them to the areas in which they originate have been developed. A great deal of valuable information has been derived from the work in this mine and much more useful and valuable information will be obtained in. the future. The writer would plead, not for the opening of experimental mines in all the important coal-producing fields in the United States, but for the opening of demonstration mines, or mines in which experiments could be made with the various details of coal mining. The United States Department of Agriculture has established, in nearly every state, stations that undertake experimental work for the benefit of the agricultural interests. In addition, small demonstration plats are set aside, in suitable locations in the farming districts, where various crops are grown under scientific direction, so that the farmers in the neighborhood can note the results obtained and profit thereby. Something like this should be done for the coal-mining industry. If experimental or demonstration mines were established, methods of working adapted to local conditions could be worked out. Owing to competition in the same markets, small capitalization, or low profits, it may be an utter impossibility for any one company to try a new method of mining. Labor conditions may prevent the trial of a new method of working. It may be impossible or inadvisable to disturb existing working conditions for fear of causing trouble among the miners through real or fancied changes in the scale of wages.

Jan 2, 1920

Jan 1, 1893

Jan 1, 1978

By Douglas R. Cook

The urgent need for new base metal ore discoveries was discussed by various authoritative exploration personnel at a CIM symposium on the future of the Canadian mineral industry held at Ottawa in 1967. Data presented at this meeting showed that approximately 150 new mines have started or restarted production in Canada since 1955. Over half of these mines were discovered prior to 1950. The distribution of Canadian ore discoveries during the last 15 years (shown in Fig. 1) illustrates a striking reduction in the discovery rate in recent years in spite of increasing exploration expenditures. These data indicate that $20 million is now spent in exploration for every significant metal deposit found, and evidently the cost of discovery is still rising. Even fewer discoveries are being made in some other important continental areas of the world such as Africa, Australia and South America. The discovery record in the U.S. is thought to be more rewarding than in Canada because the new deposits appear to be substantially larger. Fortunately, most good base metal ore deposits have attractive investment re- turns to justify large exploration expenditures. The magnitude of the exploration expenditures and the increasing need to develop additional metal resources justifies a critical review of the procedures used in the search for ore deposits. Of particular concern is the need to improve the use of exploration techniques in the attempt to obtain better discrimination and efficiency. There is a tendency by inexperienced exploration groups to think of any geological, geochemical or geophysical anomaly as an exploration target and ignore the fact that anomalies can result from many factors other than economic concentration of metals. The desire for a unique and favorable explanation of exploration data often results in too rapid a movement from the reconnaissance to the drilling stage without the use of all the relevant information.

Jan 7, 1968

By P. G. Mason

The upswing in the price of gold in 1979 prompted renewed interest in the Mercur gold property by Getty Oil Company, owner and operator, and Gold Standard Inc. of Salt Lake City, Utah, currently retaining a 15% net profits interest. Extensive geological exploration work resumed to delineate the ore reserves, and metallurgical test work was initiated under the direction of A.H. Ross & Associates. This led to the development of an aqueous pressure oxidation process suitable for treatment of the refractory ores. Subsequent geostatistical studies revealed that the distribution of high refractory ore was less than previously estimated, and thus a higher return on investment could be realized if a direct carbon-in-leach process were used despite a sacrifice in overall recovery. This paper reviews the geological and metallurgical studies that led to this final process selection.

Jan 1, 1984

Without having asked for it, the writer has apparently been drawn into the discussion regarding relative hoisting capacities which was started by Woodward Iron, egged on by Joe Haller of Cleveland-Cliffs [Mining Engineering, August p. 642] and Axel Kjelgaard [November p. 919], who took exception to Mr. Haller's remarks of tonnage hoisted and avers that they do better in Sweden. It does not appear to the writer that Mr. Haller was inclined to refer to the tonnage hoisted at Cleveland-Cliffs in a manner to imply that they claimed any hoisting record, but rather as a statement that they had hoisted a certain amount of ore during the year 1950. Mr. Haller has been in the mining game long enough to appreciate what Mr. Kjelgaard did not apparently take into consideration, that length of haul, shifts hoisted, nature of ore, method of loading and the many other factors which influence the hoisting cycle make a comparison of tonnages hoisted of two given mines almost an impossibility. Mr. Cheyette sent you .a copy of his letter to Bob Manegold relative to the capacities of the Orient #2 mine. There are several mines around the Country which constantly set up records about which little or nothing at all is ever heard. We cite the Snow Hill Coal Co. mine at Terre Haute, Ind., which has an automatic Nordberg hoist and which hoists 12 tons per trip or 700 tons per hr from 700 ft. This is a counter-weighted installation and a complete cycle is made every 62 seconds or 58 trips per hr. Another mine, The Potash Company of America mine at Carlsbad, N. Mex., has a Nordberg automatic hoist, hoisting eight tons per trip from 1150 ft on a one minute cycle. The materials hoisted in these two mines are ideal for automatic hoisting-they are free flowing so that no hang up is anticipated and hoisting is continuous. Multiplying out the above figures you will find that it is possible to hoist 11,000 tons in two shifts at Snow Hill or over 3 million tons in 300 days per year and over 2 million tons at Potash. Other mines have records which can be pointed to with pride. When a record for one year is established, it doesn't stand too long as here in America the ambition of all the men connected with the operation forces them on to larger tonnages. T. C. WIEDENHOEFER MANAGER MINE HOIST DEPARTMENT NORDBERG MANUFACTNRING CO. MILWAUKEE, WIS.

Jan 1, 1952

By R. L. Rickett, W. C. Leslie

The influence of deoxidation practice, prior thermal history, and aging time and temperature on the strain-aging behavior of low-carbon open-hearth steels was investigated. The criterion of aging employed was the increase in yield strength in the tensile test, after straining and aging. Composition, prior heat treatment, and aging conditions were all found to be important in governing the strain-aging characteristics of these steels. THAT deoxidation changes the strain-aging propensities of low-carbon steels has been known for a long time, but there has been little agreement, and even contradiction, between results obtained by different investigators and between results obtained in the laboratory and in the mill. This investigation was begun in the hope that some of the uncertainties connected with the strain aging of commercial steels could be eliminated. In considering this problem, it was necessary to define strain aging and to examine the methods used to measure this property. Strain aging can be defined as the changes in properties of a metal or alloy with time, after cold working. The rate at which these changes occur increases as the temperature is raised above atmospheric. The requisite plastic strain is the principal distinction between strain aging and quench aging, the latter being due to precipitation from supersaturated solid solution. Strain aging is also characterized by rapid attainment of maximum hardness at high aging temperatures and lack of softening (overaging) at low aging temperatures. Several possible criteria of strain aging have been listed by Sachsl and by Davenport and Bain.' Because changes in mechanical properties are the most easily measured and the most commonly used, consideration of methods to be used in this investigation was confined to three tests: tensile, notch-impact, and hardness. Hardness tests are the most economical and easiest to perform, but produce only one measure of strain aging. Also, as pointed out by Felmly, Hartbower, and Pellini,³ hardness changes due to aging are not pronounced for steels containing more than 0.15 pct C. Notch-impact tests require careful preparation of large numbers of specimens. Above and below the transition temperature the test lacks sensitivity; furthermore, it is extremely difficult to impart a uniform strain to the specimens, followed quickly by aging and final testing; machining must generally take place after straining. For these reasons, the tensile test was selected for use. Although this test requires a considerable expenditure of time, labor, and money in preparation of the specimens and performance of the test, more information can be gained than from any other single mechanical test, information which includes upper and lower yield points, yield-point elongation, tensile strength, strain-hardening exponent, reduction of area, and elongation. Low and Gensamer' and Schwartzbart and Low5 lso used the tensile test, taking the increase in flow stress after straining in tension and aging as a measure of strain aging. In our work, as in theirs, each specimen was strained an arbitrary amount, sufficient to pass through the

Jan 1, 1954

By John F. Frawley

This article in all probability will raise some serious doubts as to whether the coal industry-without a national, long-range commitment to coal-can, or should, attempt to meet the capital demands necessary to double coal production in the next 10 years. AMAX Coal, incidentally, doubled its annual coal productive capacity in the past five years from 11 million tons in 1969 to 22 million tons in 1974. Our 1973 annual report stated that we were aiming to triple our 1973 capacity to 50 million tpy by 1978.

Jan 5, 1975

We wish to congratulate the authors on a fine presentation of a difficult and interesting problem. We fully support the findings that liquid or even mushy center reduction has no place in the production of quality steels. We also agree with the findings, or implications, that internal bar quality is not made in the rolling stands, but in the caster. This is the main reason why Inland caster exclusively uses the submerged casting technique after a few months of familiarization with open casting. The metallurgical advantages of combining in-line reduction with a caster are actually indirect. The use of submerged casting and refining powder permits casting of fine grained aluminum killed steels without resorting to expensive grain refiners and cuts down or eliminates reoxidation during casting. Immersion of a snorkel into a small mold may lead to several operating difficulties. Hence, the presence of in-line reduction enables the section to be cast into a large mold, at high output rates, while obtaining some product size flexibility. The capital and operating costs of a caster-- in-line mill are lower than those of the traditional installation with a separate reheating furnace and billet mill. Admittedly, in-line reduction represents an additional challenge to the steelmaker, maintenance man, and metallurgist.

Jan 1, 1972

Jan 1, 1940

By Jan M. Mutmansky, Gordon H. Walrod, Y. J. Wang

The approach proposed in this paper is, as stated by the authors, an update of methods well discussed in the literature. The authors are to be congratulated for their excellent effort in quantifying a difficult problem with realistic cost data. Economic analysis of the components of a mine ventilation system is complicated by both the dynamic nature of the system and the uncertainty as to the time when system changes occur. We wish to address three specific areas of this paper which require further consideration: shaft designed air capacity, shaft location, and economic criteria used within the analysis

Jan 11, 1979

By R. P. Fischer

A large production of vanadium during the war helped Germany to meet her critical requirements for the ferroalloy metals. Vanadium was needed not only in the ordinary high-speed too1 steels, but in other as a substitute for chromium, nickel, and molybdenum, which were scarce. Lacking a source of vanadium ore, however, the vanadium was obtained as a by-product of the steel industry—va-nadium-bearing pig iron smelted from iron ores containing about o. I per cellt V was blown in converters to yield vanadium-rich slag, from which vanadium was recovered by chemical treatment. The production capacity obtained was said to be about 6,500,000 lb. of vanadium a Year. Although the general Processes of Preparing vanadium-rich slags as well as the recovery methods described herein are known, some of the details presented may be of interest to both the American steel industry and the vanadium producers. No adequate data on the cost of the vanadium produced in Germany are known, but it seems likely that the cost exceeds the commonly quoted domestic price of about $1.10 per pound of contained VzOa. Information on the German vanadium production was obtained by a team of geologists from the Geological Survey* United States Department of the Interior, during investigations in May and June 1945 of the German utilization of low-grade raw materials. These investigations were sponsored by the Chief of Engineers, War Department. It is a pleasure to acknowledge the aid obtained from Messrs. H. C. Smith and J. D. Dickerson, investigators assigned to the Army Ordnance section of C.I.O.S., and Mr. C. F. Park, Jr., of the Geological Survey team. The data on vanadium recovery from iron ores were obtained from the Kaiser Wilhelm Institut fiir Eisenforschung, the Hermann Goring steel plant at Watenstedt, and from notes made by other investigators at other German steel plants. Preparation of Vanadium-rich Slags Most German iron ores contain only about 0.1 per cent vanadium, or even less, but some of the scandinavian iron ores available to the German iron industry in the past contain a little more than 0.1 per cent. In general German practice of vanadium recovery, nearly all of the vanadium in the ore goes into the pig iron, which is blown in the Thomas converter, yielding a slag containing about I per cent V. This slag is remelted, the vanadium again going with the iron, which is again blown in a converter, yielding a slag that averages about 10 per cent V. This slag is treated at special chemical plants, by the process of a sodadizing roast, water leach, and acid precipitation of vanadium oxide. The Herman Goring steel plant at Watenstedt used the low-grade Salzgitter iron ores, the average composition of which is shown in Table I, column I. The acid and basic iron produced in the blast furnaces contained about 0.3 per cent V. A Thomas

Jan 1, 1948

By R. P. Fischer

A large production of vanadium during the war helped Germany to meet her critical requirements for the ferroalloy metals. Vanadium was needed not only in the ordinary high-speed too1 steels, but in other as a substitute for chromium, nickel, and molybdenum, which were scarce. Lacking a source of vanadium ore, however, the vanadium was obtained as a by-product of the steel industry—va-nadium-bearing pig iron smelted from iron ores containing about o. I per cellt V was blown in converters to yield vanadium-rich slag, from which vanadium was recovered by chemical treatment. The production capacity obtained was said to be about 6,500,000 lb. of vanadium a Year. Although the general Processes of Preparing vanadium-rich slags as well as the recovery methods described herein are known, some of the details presented may be of interest to both the American steel industry and the vanadium producers. No adequate data on the cost of the vanadium produced in Germany are known, but it seems likely that the cost exceeds the commonly quoted domestic price of about $1.10 per pound of contained VzOa. Information on the German vanadium production was obtained by a team of geologists from the Geological Survey* United States Department of the Interior, during investigations in May and June 1945 of the German utilization of low-grade raw materials. These investigations were sponsored by the Chief of Engineers, War Department. It is a pleasure to acknowledge the aid obtained from Messrs. H. C. Smith and J. D. Dickerson, investigators assigned to the Army Ordnance section of C.I.O.S., and Mr. C. F. Park, Jr., of the Geological Survey team. The data on vanadium recovery from iron ores were obtained from the Kaiser Wilhelm Institut fiir Eisenforschung, the Hermann Goring steel plant at Watenstedt, and from notes made by other investigators at other German steel plants. Preparation of Vanadium-rich Slags Most German iron ores contain only about 0.1 per cent vanadium, or even less, but some of the scandinavian iron ores available to the German iron industry in the past contain a little more than 0.1 per cent. In general German practice of vanadium recovery, nearly all of the vanadium in the ore goes into the pig iron, which is blown in the Thomas converter, yielding a slag containing about I per cent V. This slag is remelted, the vanadium again going with the iron, which is again blown in a converter, yielding a slag that averages about 10 per cent V. This slag is treated at special chemical plants, by the process of a sodadizing roast, water leach, and acid precipitation of vanadium oxide. The Herman Goring steel plant at Watenstedt used the low-grade Salzgitter iron ores, the average composition of which is shown in Table I, column I. The acid and basic iron produced in the blast furnaces contained about 0.3 per cent V. A Thomas

Jan 1, 1948

Jan 1, 1879