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By K. D. White, Chester W. Washburne

Colombia has an almost ideal situation with lespect to the world's markets, being only a short distance from the Panama Canal and the West Indies. The sailing distance from its Caribbean ports to New York is less than that from Tampico. Geographically, Colombia consists of three systems of broad mountain ranges separated by two long narrow valleys. The Cauca River valley separates the Western or Coastal range from the Central range. On the west side of the Coastal range are the Atrato and San Juan Rivers. The Central and Eastern ranges are separated by the Magdalena River valley. In the department of Santander the Eastern range divides, one branch continuing northward as the Cordillera of Perija, the other turning eastward across Venezuela as the Cordillera of Merida. Between these ranges is the great basin occupied by Lake Maracaibo. These valleys consist mainly of long narrow reentrants or tongues of Tertiary sediments between the older rocks of the mountain ranges. The late Miocene and younger sediments seem to have been deposited in separated basins, but the Cretaceous and possibly some earlier Tertiary strata were laid down more or less continuously over a great part of Colombia and Venezuela. These strata were subsequently folded into the present ranges. The deposition of the Cretaceous and of some of the Tertiary was in a great sea, the main land mass being in Brazil, with land probably along some of the cores of the present mountain systems. The sediments, except the Lower Cretaceous, vary markedly in character and thickness. An illustration is seen in the massive series of non-marine conglomerates and sandstones of the upper Magdalena River valley, near Honda, which are almost wholly wanting in the coastal sections where marine sediments prevail. The oldest rocks bearing on the search for oil are the black carbonaceous and bituminous shales, limestones, and cherts of the upper part of the Lower Cretaceous. These probably are the main source of oil in both Colombia and Venezuela. They include thick bodies of true "oil shale." Above the carbonaceous and bituminous beds, lies a series of many thousand feet of clastic sediments. The most noticeable and easily recognizable formation among these clastic sediments is the "coal-bearing series," which may be either upper Cretaceous or Eocene. The

Jan 1, 1923

By Dave H. Barnett, Brij M. Moudgil

The flotation technique as employed by Florida phosphate producing companies for the beneficiation of fine phosphate particles has been standardized over the years. Lower recoveries of coarse phosphate rock by froth flotation technique, however, led to the development of new methods based on skin flotation of phosphate agglomerates. Recent developments of floating coarse rock in large flotation machines have not yet convinced the rock producers of their higher separation efficiency. It is interesting to note that the selection of a particular machine is still based on equipment preference by an individual company as well as proven performance of a particular machine for upgrading a specific material. Various techniques which have been developed to beneficiate the coarse phosphate rock have been discussed. Performance of the individual techniques is presented.

Jan 1, 1980

By Cyril Smith

THE method of thermal analysis, so important in the development of metallographic science, has of recent years been falling into disuse owing to the development of other physical methods which give results easier of interpretation and which can be used for the study of either equilibrium or transitional conditions because they do not require a continuously changing temperature. Nevertheless thermal analysis remains useful in the study of reactions that take place rapidly, and the simplicity of the experimental technique and the general availability of the apparatus involved are points in its favor. Theoretically, thermal analysis is capable of giving specific and latent heat measurements and therefore should permit the study of reactions on a more fundamental basis than any other method. It is, however, difficult or impossible to obtain quantitative heat measurements from cooling curves obtained in the usual way. Even if the furnace containing the sample is cooled or heated at a linear rate, or if a gradient furnace is employed to maintain a constant rate over a large range of tempera-ture, the heat flow from or to the specimen depends on its previous his-tory, for the difference of temperature between the specimen and its surroundings varies. The emissivity of the specimen surface, moreover, is unlikely to be constant. The able mathematical analysis by Russell,1 although it prevents misinterpretation of data, has an effect rather the reverse of that intended, and leaves the reader doubtful of the possibility of ever obtaining quantitative results from thermal curves. Nothing can be done to apply thermal analysis to the study of equilib-rium conditions of reactions that are not completed at rates of tempera-ture change below about 1° C. per minute, and this unfortunately excludes most solid transformations in alloys. ? For the determination of liquidus

Jan 1, 1939

By Maurice Rey, Victor Formanek, Paul Chataignon

IT is found when floating oxidized lead ores by sulphidization, that the presence of calcium salts in the water is usually detrimental and lowers the recovery. This effect is particularly marked in dry countries such as North Africa, where the waters often carry large amounts of calcium sulphate and where the ore may even contain gypsum. This effect is particularly marked in dry countries such as North Africa, where the waters often carry large amounts of calcium sulphate and where the ore may even contain gypsum. The effect of calcium salts is readily visible. Whereas in their absence cerussite is quickly stained brown and then .black by sodium sulphide, in their presence the mineral remains very light in color. A similar- effect is produced when barium sulphide is used as a sulphidizing agent instead of sodium- sulphide. Magnesium salts have little or no effect and even tend to reduce the detrimental effect of calcium salts. A study of this phenomenon indicates that it is due to the precipitation of calcium or barium carbonate in contact ,with the mineral simultaneously with the formation of lead sulphide.

Jan 1, 1950

By Walter S. Weeks

IN this paper the effect of natural ventilation pressures is considered a part of the mine resistance and it is shown that their effect on the mine resistance is not the same as the total natural ventilation pressure of the shafts if the mine has several levels. It is shown that increasing the fan pressure causes the division of the air to approach the condition that would obtain if there were no natural ventilation pressure present. It is shown that if an appreciable difference in pressure is maintained between the beginning and end of a group of splits, the value of the integrated effect of the natural ventilation pressures on the individual splits does not change substantially with moderate changes of this pressure. A method is outlined for determining the resistance factor of the mine and the value of the effect of natural ventilation with the fan operating; also a method for determining this factor when circulation is caused by natural ventilation alone. NATURAL VENTILATION PRESSURE Natural ventilation pressure (N.V.P.) is caused by the difference in weight of the air in two similar columns between two horizontal planes, and the difference in weight is caused principally by the difference in temperature of the two columns. The fan pressure causes some variation in density, but, since it is usually small and affects both columns, its effect is relatively unimportant. It has been suggested that "N.V.P." be called "stack effect"; but, since the term N.V.P. was used in a previous Institute paper,' applied in exactly the same manner, the term will be used. FRICTIONAL RESISTANCE The frictional resistance to flow in a mine without natural ventilation may be expressed as RQ2 where R is a constant for a given air density and Q is the rate of flow. This frictional resistance plus the effect of velocity changes will be called the F pressure (F.P.) and a curve of F.P. against Q, the F characteristic of the mine. If a pressure is applied to a mine by a fan, the air flow so adjusts itself that the drop in pressure through any path from entrance to exit of mine, due to frictional resistances and velocity changes, is the same as that in any other path. The mine resistance varies as the square of the quantity. The air distribution without N.V.P. will be called "normal." NATURAL VENTILATION PRESENT When N.V.P. is irregularly distributed in a mine, it is more convenient in analysis to consider the N.V.P. as a part of the duct resistance. If it is so considered the resistance no longer varies as the square of the quantity, and if N.V.P. exists between levels the distribution of the air is no longer normal. The total N.V.P. of the mine is the pressure caused by the full length of the shafts. If a mine has several levels, N.V.P. exists

Jan 1, 1944

By W. Robert Power

Petrographically these range from true granite and syenite to gabbro and anorthosite. Commercial limestone is any sedimentary rock composed predominantly of the minerals calcite and/or dolomite. Commercial marble is any crystalline rock composed predominantly of calcite, dolomite or serpentine that is capable of taking a polish. Marble comes in a wide variety of color, texture and pattern. Many commercial marbles are unmetamorphosed limestone, to the geologist or petrologist but if they take a polish, are classified as marble.

Jan 6, 1972

By AIME AIME

CADWALLADER EVANS JR. has long been a leading figure in the anthracite mining industry and one of Pennsylvania's prominent citizens. He is, in fact, a native son, having been horn in Pittsburgh on Sept. 17, 1880. At Lehigh, from which he graduated in 1901 with the degree of Mechanical Engineer, Tom Girdler was a classmate, and both were active in football affairs. Going hack to Pittsburgh, he got his first job as trouble shooter for the Oliver Iron & Steel Co. A year later he entered the coal industry, getting a job with the Blaine Coal Co. as inspector of construction and later was superintendent of the Blaine mine at Elizabeth. Pa.

Jan 1, 1943

By S. H. Ash

Foreman remains key man in any safety program, as men attracted to the industry must be trained in safety thinking. Diesel engines underground aid safety and widespread use of roof bolting is reflected in reduction of roof-fall fatalities.

Jan 2, 1953

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 Samuel M. Cassidy

The exact date of man's first use of coal is lost in antiquity. The discovery that certain black rock would burn was undoubtedly accidental and probably occurred independently and many times in the world over thousands of years. It is quite likely that these independent discoveries were made when primitive man chanced to build camp fires on exposed ledges of a black stone, then was amazed when it caught fire. The Chinese recorded the use of coal 1100 years before the Christian Era. And, from the Bible we learn that King Solomon was familiar with coal in what is now Syria. In Wales, there is evidence that the Bronze Age people used coal for funeral pyres, and it is known that the Romans used this fuel. There are other ancient references. So the knowledge that coal would burn, and even some uses of that knowledge, goes back for thousands of years. However, practical and consistent use of coal seems to date to England in the Middle Ages. COAL IN AMERICA In the Americas, there is evidence here and there of a slight use by the Indians. However, the first recorded discovery of coal, in what is now the U.S., was by French explorers, who reported a "cole mine" on the Illinois River in 1679. Following this, other discoveries were made by French and British explorers, but the first recorded actual usage was in Virginia in 1702, where a French settler was granted permission to use coal for his forge. Earliest recorded commercial mining was in 1750, from the James River coalfield near Richmond, Va., a deposit now abandoned. Besides local consumption from this field, shipments were made to Philadelphia, New Pork, and Boston. During the Revolution this coal was of importance in the manufacture of shot and shell; so important, in fact, that the British sent an expedition in 1781 to destroy the iron works and

Jan 1, 1973

By S. N. Dixon

Sampling and assaying procedures were developed to obtain unbiased and reasonably accurate Au grade estimates in drill samples fm a coarse gold deposit. Gold grade comparisons were made by assaying 3 (1 assay ton) splits from each drill interval, then processing the entire reject thru a pilot plant for a blocked out zone. The result comparing the assay splits to the pilot plant results gave a ratio of 1 to 1.07. Another technique was developed to detect drill samples which has a coarse gold content by monitoring the varience. Testwork could be done on a 1 kg sample to improve the accuracy of the grade estimation if the variance was high for a drill interval.

Jan 1, 1984

By K. P. Wang, Virgil L. Barr

The U.S. Minerals Attaché Program, similar to the scientific and technical attache programs of other industrialized nations, is designed specifically to keep surveillance on significant worldwide developments in minerals, metals, and fuels. Knowledge of international minerals developments is essential for both domestic planning and conduct of foreign affairs. CONTROLLED BY DEPT. OF STATE Ten minerals specialists-eight minerals attaches and two petroleum attachés-man this far-flung, worldwide program for the U.S. Government as best they can. Minerals attach& also handle oil, in posts lacking petroleum attaché. The legislative authority for the Minerals Attaché Program is the Foreign Service Act of 1946 and succeeding amendments and Presidential Executive Orders. Therefore, this program is controlled by the Department of State. Interior (representing the Bureau of Mines) and State collaborate in policy formation and direction by means of a "memorandum of agreement" which covers establishment of posts, selection of officers, contents of reports, and supplemental training. State also has about half a dozen nonspecialist officers to complement the work of the minerals and petroleum attaché. It is not the intention here to evaluate the administrative arrangements of this program but rather to describe it and to provide examples of the important job it is doing.

Jan 11, 1965

Jan 1, 1946

By James Douglas

As the operation of light railroads is important to the mining industry, the following statistics of the Arizona Southeastern Railroad may be of interest. When the traffic of the Bisbee copper-mines reached 20,000 tons per year the necessity of better transportation than that afforded by eighteen- and twenty-horse and mule teams became imperative on the score of both cheapness and convenience. Before deciding on the construction of a railroad, the Copper Queen Company made a thorough experiment in transportation

Jan 1, 1899

Jan 1, 1938

By T. M. Barry

HOW often have those who make mining a career said that, "mining is different"? This kind of feeling often expresses itself in talking shop with men of other industries. And there is no doubt about it; mining is different. There are different marketing problems, different production problems, and we certainly have different personnel problems, to cite but a few. Mining people have recently been discovering though, that many of their problems are not unique to mining. They are beginning, in fact, to find that many of them are dead ringers for problems that other industries have had to face and solve years ahead of mining.

Jan 6, 1954

By A. J. W. Schwandt

Magmont is a venture jointly owned by Cominco American Incorporated of Spokane, Washington and Dresser Minerals, Division of Dresser Industries, Houston, Texas. Cominco American assumed direction of the operation in 1961 and completed exploration, preproduction planning and development, and is now the operating partner managing the operations. The plant has a rated capacity of 4200 tpd and produces in excess of 60,000 tons of lead per year. [ ]

Jan 1, 1970

Jan 1, 1923

Jan 1, 1923

By W. D. Roberts

INTERGRANULAR corrosion of metals and alloys has been extensively investigated and the current conclusions are summarized in the Symposium on Stress-Corrosion Cracking of Metals.' It appears, however, that the relative importance of the various factors involved in the mechanism is still obscure. Several recent, independent studies, in combination with available X ray data op preferred orientation, indicate that there may be a direct correlation between relative orientation of contiguous grains and susceptibility to intergranular corrosion. The object of the present note is to show the nature

Jan 1, 1951