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By George H. Cook

At first sight this subject seems to belong to pure theoretical geology, but examination will soon show that it has important practical and economic interest to the mining engineer. The conclusion that all the northern portions of our country, as well as of the eastern continent, have, in the later periods of geological history, been covered with a thick bed of ice, is now accepted by geologists. This bed of ice, except in its greater magnitude, was like the modern glaciers of the Alps, and other mountains which extend above the line of perpetual snow. The marks it has left upon the surface show that it was comparatively thin on its southern edge, but that its thickness was much greater a little further north, and that it was several thousand feet thick at its kenviest parts. This variation of its surface would give it a descending slope towards the south, and cause the mass of ice, like a semifluid substance, to move in that direction,

Jan 1, 1879

By Joseph E. Pogue

The prices of crude petroleum and its derivatives have shown an upward trend from 1915 to 1920, and a downward trend from 19'20 to 1923, see Table 1. Over the former period, oil prices were dominated by the rapidly increasing demands and inflation incident to the war and its aftermath, while over the latter period oil prices were influenced at the outset by deflation and then by the conditions of overproduction that have characterized the past three years. he purpose of this paper is to analyze the broader features of the more recent price movements in the petroleum industry and to relate these features to basic economic conditions in the industry. Index Numbers of Oil Prices The analysis and comparison of price movements may be facilitated by converting actual prices into relative prices, or index numbers, with 1913 taken as a base of 100. In this way, the various price groups are expressed as percentages of the 1913 prices and may thus be readily compared with one another or with the average prices of other commodities similarly expressed. Table 1 gives the index numbers representing the average prices of crude petroleum, gasoline, kerosene, fuel oil, lubricating oils, and all commodities. The last named is the index of all commodities as published by the U. S. Bureau of Labor Statistics and is widely accepted as the official measure of the general price level. The index numbers of oil prices were calculated by the writer from weekly quotations published in trade journals. Fig. 1 shows in graphic form the trend of oil prices by months over the period 1920-23. It may be observed that the prices of crude oil and its derivatives move in rough conformity with one another; tend to follow

Jan 1, 1924

By Charles R. Keyes

PAGE I. Introductory............ 140 II. Location and History...........140 III. Surface-Relief of the District....... 141 IV. General GeoloGic Features........ 142 1. Main Relationships and Map....... 142 2. Résumé of Geologic History..143 V. Geologic Formations Represented...144 1. Broader Considerations......... 144 2. Geologic Section.......... 145 3. Nomenclature.......... 146 4. El Pasan Limestones..146 5. Santa Rita Limestone.... 146 6. Silver Shales........... 147 7. Bella Shales........... 147 8. Berenda Limestone..147 9. Grande Limestone... 148 10. Lake Valley Limestone........ 148 11. Sierra Limestone.......... 149 VI. Unconformities........... 149 VII. Geologic Structure.......... 150 1. Main Characteristics......... 150 2. Folding........... 1.50 3. Faultings........... 150 4. Relations of the Eruptives...153 VIII. Geologic Relations OF the Ore-Bodies...... 154 1. Governing Factom......... 154 2. Position.......... 154 3. Relations to Foldings...155 4. Relations to Lines of Dislocation... 15.5 5. Relations to Present Surface.Relief..156 6. Relations to Eruptive Rocks...157 7. Relations to Lithologic Nature of the Rocks.... 158 IX. MINERALOGIC CHARACTER OF THE ORES...... 158 X. Origin of the Ore.Deposits..159 1. General Statement......... 159 2. Original Source of the 0re.Materials...160 3. Contact-Metamorphism of the Region... 161 4. Process of 0re.Concentration..162 5. Lowering of Ground-Water Level..162 6. Formation of Cerargyritic Ores...163 XI. Recapitulation........... 168

Jan 1, 1909

By Robert K. Warner

Is an accurate measurement of the efficiency of a screen under a given set of operating conditions valuable? If so, what is the efficiency of a screen and how can it be measured? Sizing, especially of the finer sizes of material, has increased in importance in the development of flow sheets as a result of the perfecting of the rapid vibrating screens. More consideration should be given screens in the preparation of ball-mill feed, where they permit the admission of a dryer feed than the classifier. Where possible, the introduction of a screen ahead of the primary ball-mill, and the diverting of ore below, say, 4 mm. to a secondary mill, might result in a greater overall economy because of the thicker feed and the better adjustment of crushing media and mill operation to the reduction demanded. With the present trend back toward a combination of gravity methods and flotation, rather than flotation alone, the accurate, economical sizing possible with the new screens makes fine jigging a method to be considered. W. o. Borcherdtl and John Bland= discuss the screening problem and also the value of close sizing in the concentration of some of the rare-metal ores. If a screen is to be used, it should be selected in competition with others; other things being equal, that screen which makes the cleanest oversize should be preferred. The quality of the screening and the tons handled per dollar together determine the choice and, therefore, both of these must be accurately measured if a correct decision is to be reached. Too frequently in mill design, the capacity has been considered almost to the exclusion of the completeness with which the undersize is separated from the oversize. It is, of course, possible to increase the aperture of the screen, and thus insure the removal of a sufficiently coarse

Jan 1, 1924

Jan 1, 1929

By H. H. Hausner, O. V. Roman, F. V. Lenel, G. S. Ansell

The radial shrinkage during sintering of cylindrical compacts and loose aggregates of copper powder was measured. It was found to be nonuni-form from top to bottom of the samples and to depend upon the method of supporting them. The non-uniformity is due to the effect of gravity forces during sintering. Since gravity has an effect in sintering without externally applied stresses, no sharp dividing line can be drawn between conventional sintering and hot pressing. RECENT investigations of the sintering behavior of compacts1 and of loose powder aggregates2 have indicated that forces, other than those arising from surface tension effects, may play a role in shrinkage. In compacts it was shown that residual stresses from the pressing operation influence shrinkage behavior. In loose powder aggregates gravity forces due to the weight of the powder affect the ratio of shrinkage in the vertical and the horizontal direction. The main effort in the work reported here was to show that gravity plays a role also in the sintering of compacts. A few additional experiments were made confirming the effect of gravity in the sintering of loose powder aggregates. EXPERIMENTAL PROCEDURE Compacts and loose powder aggregates were prepared from irregularly shaped, electrolytic copper powder. Prior to use the powders were reduced 30 min at 400°C in dry hydrogen to remove surface oxides. Then the -325 mesh size fraction was separated from the -100 + 325 mesh fraction. The compacts were pressed at a pressure of 10,000 psi from 50 g of powder in a hardened steel die, 1 in. in diam. The height of the compacts was 0.725 i 0.005 in. An effort was made to get as uniform a green density distribution in the compacts as possible. The walls of the die were lubricated with a suspension of 3 pct of zinc stearate in acetone and the compacts were pressed using double action by first pressing the powder at 1200 psi with the die barrel supported, then removing the sup- ports and pressing to final pressure of 10,000 psi with the die barrel floating. The pressure was maintained for 10 sec. The compacts were sintered at a temperature of 925°C, generally for 1 hr. In order to maintain uniform temperature they were sintered in boats made from cylindrical copper blocks. The blocks were 2 in. in diam, either 2 or 2 1/2 in. long and, split to form the body of the boat and a lid. The body of the boat contained a cavity 1 3/8 in. wide, 1 in. deep and either 2 1/8 or 1 3/8 in. long. The longer cavity accomodated two samples, the shorter one only one sample. The uniformity of temperature distribution within the boats was checked with thermocouples welded to the top and bottom of the samples. The maximum variation between top and bottom temperatures was i 1/2°C. The actual sintering temperature was held constant within ±2°C. In order to determine the effect of gravity forces, i.e., the weight of the compacts, upon shrinkage, they were supported in the following ways during sintering: a) Full Bottom Support. The compacts rested either on a flat alundum disk or on alundum powders. b) Partial Bottom Support. The compacts rested on a graphite cylinder, 0.3 in. in diam which formed a projection on a larger graphite disk. It is difficult to balance the compact on the small projection. To avoid having the compact tip, a small hole was drilled through the compact and through the graphite disk and its projection. The graphite disk was then suspended from the lid of the boat by a thin iron wire which passed through the holes in the disk and the compact. c) Top Support, first type. A hole 3/32 in. in diam was drilled diametrically through the green compact 3/16 in. from the top of the compact. The compact was sintered suspended from an alundum rod (thermocouple protection sleeve) inserted into the hole. d) Top Support, second type. A hole was drilled axially through the center of the compact. The upper part of the hole from the top surface of the compact one fourth of the way down was 1/16 in. in diam; the lower part of the hole from the bottom surface three fourth of the way up was 3/32 in. in diam. The compact was suspended from the lid of the boat by an iron wire passing through the upper part of the hole and then tied into a knot. The loose powder aggregates were made by filling l in. deep, l in. diam cylindrical graphite molds with -325 mesh powder. To achieve uniform density in all the loose powder aggregates, the powders were settled in the molds by placing the

Jan 1, 1963

By M. T. Simnad, G. Derge, I. George

Measurements of current efficiency on iron-silicate slags in iron crucibles showed that conduction is about 10 pct ionic in slags with less than 10 pct silica and about 90 pct ionic in slags with more than 34 pct silica, increasing linearly in the intermediate range. The balance of the conduction is electronic in character. Silicate ions are discharged at the anode with the evolution of gaseous oxygen. Transport experiments show that the ionic current is carried almost entirely by ferrous ions, which may be assigned a transport number of one. THERE has been increased evidence in recent years that the constitution of liquid-oxide systems (slags) is ionic.1-3 The principal studies designed to establish the structure of liquid slags have been by electrochemical methods', " and conductivity measurements1,6,7 which also have indicated the presence of semiconduction in several silicate systems1,4-0 and in pure iron oxide.' It is well known that many slag-forming metallic oxides have an ionic lattice type in the solid state, and their properties are determined to a large extent by the lattice defects and ion sizes. As Richardson8 as pointed out, the detailed models of liquid slags cannot be found on thermodynamic data only but "must rest on a proper foundation of compatible structural and thermodynamic knowledge, combined by statistical mechanics." A careful thermodynamic study of the iron-silicate slags has been carried out by Schuhmann with Ensio9 and with Michal.10 They obtained experimental data relating equilibrium CO2: CO ratios to slag composition and made thermodynamic calculations of the activities of FeO and SiO, and of the partial molal heats of solution of FeO and SiO2 in the slags. It was found that the activity-composition relationships deviate considerably from those to be expected from an ideal binary solution of FeO and SiO2. However, the partial molal heat of solution of FeO into the slags was estimated to be zero. Their experimental results were correlated with the constitution diagram for FeO-SiO2 of Bowen and Schairer,11 with the results of Darken and Gurry" on the Fe-O system, and with the work of Darken"' on the Fe-Si-O system. All these studies were found to be consistent with one another. The variation of the mechanism of conduction with composition in the liquid iron-oxide-silica system in the range from pure iron oxide to silica saturation (42 pct SiO2) in iron crucibles was reported in a preliminary note." The current efficiency, or conformance to Faraday's law, showed some ionic conductance at all compositions, the proportion increasing with the concentration of silica. The current-efficiency experiments since have been extended. Furthermore, transport-number measurements have been completed in silica-saturated iron silicates to determine the nature of the conducting ions. Experimental Current Efficiency in Liquid Iron Oxide and Iron Silicates using Iron Anodes: This study was carried out by passing direct current through slags in the range from pure iron oxide to iron oxide saturated with silica (42 pct silica), using pure iron rods as anodes and the iron container as the cathode. A copper coulometer was included in the circuit to indicate the quantity of current passed during electrolysis. Assuming that the cation involved is Fe-+, the theoretical quantity of iron lost from the anode according to Faraday's law may be calculated and when compared with the actual loss observed, gives an indication of the extent to which Faraday's law has been obeyed. It also gives an indication of the presence and extent of ionic conduction in the melt. Preparation of the Slags: About 100 g of chemically pure Fe,O, powder is placed in an iron pot which is heated by induction until the contents liquefy. In this way, FeO is produced according to the reaction Fe2O3 + Fe = 3 FeO. More Fe2O3 or SiO, powder is added and, when a sufficient quantity of molten slag is obtained, the induction unit is turned off, the pot withdrawn, and the molten slag poured on to an iron plate. Homogenization and Electrolysis of the Slag: Apparatus—After considerable development, the setup illustrated in Fig. 1 proved to be quite satisfactory. A is an Armco iron cylinder, 1 in. ID and 1/8 in. wall, consisting of three sections placed one on top of the other. The bottom section is a pot about 5 in. long with a small hole drilled in its bottom to allow withdrawal of gases during evacuation of the apparatus. The middle section is 6 in. long and consists of a pot which serves as the slag container, while the top section is a hollow-cylinder continuation of the slag-container pot. The height of this latter section is about 5 in., giving an overall length of approximately 16 in. The iron cylinder is constructed in this way for ease of fabrication, the individual sections becoming welded together after the

Jan 1, 1955

By Charles M. Rolker

The Allouez Mine is situated in section 31, town 57, north of range 32 west, Michigan. The mine is being worked in a conglomerate bed, which conglomerate is generally conceded to be the continuation of the Albany and Boston conglomerate of Honghton County. Besides the well-known Calumet and Hecla with the adjoining Osceola, both working on the same bed, and the new location, the Seneca, now being tried on the Kearsarge conglomerate, the Allouez Mine is the only one working on a conglomerate bed. The Albany and Boston, in Houghton County, of which, as said before, the Allouez is supposed to be the continuation, shares with all the remaining conglomerate beds, near and around Portage Lake, the property of being non-quartziferous, while the conglomerates of Keweenaw County are all highly quartziferons in character. This change takes place, according to Professor Pumpelly, about six miles northeast of Portage Lake. The Allouez conglomerate, with a dip of 38" 15' and a general course of about 36' east of north, is overlaid by a trap, and has as its footwall an amygdaloid. The trap is followed by a series of amygdaloidal melaphyres and true amygdaloids, further on by the greenstone and ashbed; towards the lake shore alternating traps and conglomerates are found. At the footwall of the Allouez conglomerate, an amygdaloid lies, the thickness of which is not known, which is also the case with the other formations, accurate surveys and geologiwl researches of this district having, as I was informed, never been made. About 198 meters (650 feet), horizontally measured, from the Allouez conglomerate another amygdaloid bed can be traced, on which the present rockhouse stands, further on a melaphyre is exposed, and then follow the diverse conglomerates, the Calumet, the Kearsarge, and Kingston, which, according to the last geological report, are at about the re-

By Paul Munoz

TRINIDAD, which has never been. seriously consid-ered as a large oil producer, has recently taken a new lease on its oil life through active development work being carried on by a newly organized American company that has been conspicuously successful in the short time in which it has operated on the island. From an oil operator's point of view Trinidad pos-sesses numerous natural advantages which are not found in any other oil producing country. The climate, while tropical, is healthy. The nights are always cool. Deep-water shipping ports in protected waters are available within short pipe-line distance from the pro-ducing fields. The distance from Trinidad to the At-lantic seaboard of the United States is less than from the Gulf Coast or from Mexico. The labor supply is abundant and can be had at reasonable rates. The island enjoys a good, stable government under British rule and is traversed by a net-work of excellent govern-ment roads. From a production standpoint the fields being de-veloped by Trinidad Oil Fields, Inc., the company re-ferred to above, present interesting problems which are being successfully solved. The oil sands are extremely fine; some of them having over 50 per cent passing 100- mesh screen and, with the exception of the Palo Seco field, the sands are loose, with shale-breaks and shale capping and with rock pressures running up to 600 lb. per square inch. Rotary drilling is universal, as the formations encountered are soft Tertiary shales, clays, sandy shales and sands, with occasional sandstone and lime shells, which are easily drilled with the rotary. As high as 600 ft. of hole in 24 hr. has been made in some of this company's wells. Production is at present obtained at depths ranging from 500 to 2500 ft. but further development will probably result in deeper pro-duction being obtained. The oil being produced ranges from 21 deg. to 37 deg. Bé gravity and is all asphaltic base oil.

Jan 7, 1927

By K. L. Sehgal

Minerals are the basis of modern civilization: their exploitation and effective utilization are a yard- stick for measuring the comparative prosperity of different nations. This is particularly true in India where industrialization is just beginning to pick up speed. Production targets for our Fourth Five Year Plan (1966-71) are far ahead of the figures for, say, 1950 (the year we won independence) and show the extent of the expansion. Many problems remain to be solved, not least of which is the shortage of raw materials. India is no novice at utilizing minerals. Archaeological ruins at Harappa and at other historical places in the country show evidence of the fact that the ancient Indians not only knew the art of winning minerals from the ground over 6000 years ago-they were also well acquainted with metallurgy. Some of the present sites of mineral exploitation are the same as those our ancestors worked for many centuries.

Jan 9, 1965

By S. J. Kidder

The Mogollon mining district is in the southwestern part of New Mexico near the southern end of the Mogollon range, from which the district takes its name. The town of Mogollon is but 371/2 miles in an air line northeast of Clifton, Ariz. The air-line distance from Silver City is 521/2 miles and from Tyrone, 57 miles. Supplies are transported by motor truck from Silver City. The distance by road is 75 miles, half of which is an improved highway of modern construction. Transportation has always been a large item of expense in carrying on operations in the district. Valuable ore is said to have been discovered in the Mogollon Mountains as early as 1870 but the first regular prospecting was carried on in 1875, by James C. Cooney, a sergeant from Fort Bayard. His discovery of rich silver-copper ores in the region of Mineral Creek led to the establishment of the Camp of Cooney. Remote from any settlements where there was a semblance of law and order, and harassed by the Apaches, development was slow and nearly 10 years elapsed before the village of Mogollon was established on Silver Creek. Prospecting in this section of the district had disclosed the outcrops of several promising veins containing silver-gold ores. Among the early claims located were the Last Chance, Top and Confidence, on what has proved to be the most productive vcin in the district. To the end of 1922, the Last Chance and Top claims had produced approximately 600,000 tons of ore and nearly 200,000 tons had come from the Confidence group of claims. The total value of the ore produced from this vein alone has amounted to about $9,600,000 in silver and gold. The Fanney vein was developed later and during its most active period of production contributed more than half of the output of the district. Other important locations, though far less productive than the above, were the Maude S, Deep Down, the Deadwood and the Pacific.

Jan 1, 1925

By Luis Elek

DEVELOPMENT of the cement industry in Mexico began some 40 years ago. It has gradually reached great importance in the economic life of the country and has contributed greatly to the technical and economical advances which have been so noteworthy, particularly during the last 15 years. From a modest start, the industry now comprises 18 cement-producing plants having a potential annual capacity of approximately 14 million bbl. About half the plants were built and equipped with secondhand machinery during the last world war when no new machinery could be procured. They will hardly attain full production before being modernized and reconditioned, a job now under way in several of the plants. At present, the yearly consumption is only about 8 to 9 million bbl but is steadily increasing. This is only a fraction of the cement consumed in the U.S.A., which is about 250 million bbl per year, although on the basis of consumption per capita per year, the figure is 1/3 bbl for Mexico and 1 2/3 bbl for the U.S.A. Cement consumption in Mexico is well above the average of all other Latin American countries, with the exception of the Argentine, and considering the potentialities and undeveloped riches of Mexico, the road construction and irrigation works, it is fair to assume that the Mexican cement industry will still prosper and expand in spite of temporary setbacks in the future caused by local events of economic or political nature. Portland cement is manufactured by burning a mixture of raw materials, one of which is mainly composed of calcium carbonates and the other of aluminum silicates. The most typical materials answering this description are limestone and clay, both of which occur in Mexico in many varieties. To be usable for cement manufacture limestone should contain at least 77 to 80 pct calcium carbonate. Lower grade limestone can be used for cement manufacture only if the lime content is increased by the beneficiation process, which has not yet been adopted by the Mexican cement industry. Most of the limestone used by Mexican cement plants has a calcium carbonate content of 90 to 95 pct and therefore requires addition of one or several correction materials. A typical composition of raw mix for cement manufacture is 85 pct limestone and 15 pct shale, clay or volcanic materials. Occasionally it is necessary to add a smaller amount of sand or other siliceous material to increase the silica ratio in the raw mix. Likewise, it is sometimes necessary to add 1 or 2 pct iron ore to facilitate fusion in the kiln and to obtain proper relation between alumina and iron oxide. After calcining and

Jan 1, 1953

By Grafton M. Thrasher

Discussion of the paper of GRAFTON M. THRASHER, presented at the New York meeting, February, 1916, and printed in Bulletin No. 106, October, 1915, pp. 2129 to 2138. RICHARD MOLDENKE, Watchung, N. J.-Mr. Thrasher is to be commended for developing a very interesting comparison between high- and low-carbon and silicon malleable cast irons for an equal degree of chill. His deductions are unquestionably correct, though the application to daily practice is open to serious criticism, from the standpoint of the man who receives the castings, as will be shown later on. Running over some of the points which affect the tests in question: Mr. Thrasher admits that the temperature of pouring has a serious influence on the degree of chill shown in the test plugs he made. This is a well-known fact, and I would like to add that another serious trouble comes from oxidized iron when the heats have been unduly prolonged. Such metal always shows more chilling action for a given silicon and carbon content than normally melted iron. Indeed, the test piece quoted giving the extreme of the chill line (1.07 per cent. Si and 2.47 per cent. total carbon) was such a poor heat, a ferro-silicon addition never "doctoring" up the metal sufficiently to show normal good strength. In spite of these irregularities, which would simply change the curve slightly, I take it that Mr. Thrasher's results can be accepted as reliable enough to establish the relationship of silicon and total carbon as shown. When, however, the claim is made that silicon and carbon can be substituted for each other in mixture-making (a claim which may be perfectly correct metallurgically), a very important factor is forgotten, causing the purchaser of the castings much annoyance. This is the contraction (erroneously called shrinkage) of the castings. They will no longer be true to pattern. The lower the total carbon is allowed to drop, the greater the contraction, and increasing the silicon correspondingly will not correct this trouble. No wonder that recently, in revising the Standard Specifications for Malleable Castings it was necessary to increase the variation of castings from requirements considerably over what was formerly found sufficient. The habit of running up the proportion of silicon and escaping danger from grayness of the metal by copious steel additions was evidently too tempting to manufacturers, as their molding losses were thus kept down and a very soft malleable iron resulted. The customer, however, got serious variations in his work, which was not the case when the total carbon was kept between 3.25 and 2.75, and the silicon held as low as possible without undue cracking of the hard castings.

Jan 5, 1916

By W. H. Gunniss

When the copper smelters were built, in Montana, all of the refractory products which were used in their construction were shipped in from Eastern factories. It was apparent that if a material suitable for the manufacture of these products could be found within the State, a saving of freight could be effected and a new industry built up. Prospecting for such materials was started and experiments were made with samples from numerous deposits. Considerable effort and funds were expended in an attempt to manufacture silica brick from Dillon quartz, a light colored sandstone that is found near Dillon, Mont., on the Oregon Shortline railroad. As a brick material the Dillon quartz was a failure, but it has proved very satisfactory as a silica cement. It is now being used in laying silica brick and for reverberatory furnace bottoms. A bed of quartzite that is particularly suited to the manufacture of high-grade silica brick was finally discovered at Browns Spur, 6 miles west of Anaconda. The material from this deposit is now being used in the manufacture of the Anaconda silica brick, which have gained a wide reputation for heat-resisting and lasting qualities. The analysis of an average sample of this quartz is: SiO2, 96.7; Fe2O3, 0.3; Al208, 2.5; CaO, 0.3 per cent. The very low percentage of fluxing ingredients makes this a most refractory material. All of the Anaconda silica brick are hand molded. Various types of brick machines have been tried, but the hand-mold process proved the best suited to the manufacture of silica brick from this material. The silica is first put through a jaw crusher and is then dumped into wet pans, where 4 per cent. of lime paste is added, to produce a bond. Without the lime the material would not be plastic enough to mold. After a few minutes' grinding in the wet pans the material is conveyed to the molder, who forces it into the molds by hand. The brick are then dumped on pallets and placed in the drier, where they are left. until dry enough to be set in the kilns. Some of the brick are re-pressed before being dried. They are burned about five days, in round down-draft kilns. It is not necessary to have as much heat in the kilns as the brick will be subjected to when in use in the furnaces. Montana refractories are used in smelters throughout the West. Prospecting for fire clays was also carried on. After experimenting with clays from several different deposits, it was found that a mixture of

Jan 1, 1914

By Luis Elek

DEVELOPMENT of the cement industry in Mexico began some 40 years ago. It has gradually reached great importance in the economic life of the country and has contributed greatly to the technical and economical advances which have been so noteworthy, particularly during the last 15 years. From a modest start, the industry now comprises 18 cement-producing plants having a potential annual capacity of approximately 14 million bbl. About half the plants were built and equipped with secondhand machinery during the last world war when no new machinery could be procured. They will hardly attain full production before being modernized and reconditioned, a job now under way in several of the plants. At present, the yearly consumption is only about 8 to 9 million bbl but is steadily increasing. This is only a fraction of the cement consumed in the U.S.A., which is about 250 million bbl per year, although on the basis of consumption per capita per year, the figure is 1/3 bbl for Mexico and 1 2/3 bbl for the U.S.A. Cement consumption in Mexico is well above the average of all other Latin American countries, with the exception of the Argentine, and considering the potentialities and undeveloped riches of Mexico, the road construction and irrigation works, it is fair to assume that the Mexican cement industry will still prosper and expand in spite of temporary setbacks in the future caused by local events of economic or political nature. Portland cement is manufactured by burning a mixture of raw materials, one of which is mainly composed of calcium carbonates and the other of aluminum silicates. The most typical materials answering this description are limestone and clay, both of which occur in Mexico in many varieties. To be usable for cement manufacture limestone should contain at least 77 to 80 pct calcium carbonate. Lower grade limestone can be used for cement manufacture only if the lime content is increased by the beneficiation process, which has not yet been adopted by the Mexican cement industry. Most of the limestone used by Mexican cement plants has a calcium carbonate content of 90 to 95 pct and therefore requires addition of one or several correction materials. A typical composition of raw mix for cement manufacture is 85 pct limestone and 15 pct shale, clay or volcanic materials. Occasionally it is necessary to add a smaller amount of sand or other siliceous material to increase the silica ratio in the raw mix. Likewise, it is sometimes necessary to add 1 or 2 pct iron ore to facilitate fusion in the kiln and to obtain proper relation between alumina and iron oxide. After calcining and

Jan 1, 1953

By J. M. De La Garza Cárdenas

The total production of oil in Mexico in 1942 was 34,715,547 bbl.; that is, 8,179,254 bbl. less than the amount produced in 1941. The daily average for 1942 was 95,111 bbl., while that for 1941 was I17,520 barrels. The reduction of 22,409 bbl. per day in production was due to a decrease in exports because of the scarcity of tankers. This reduction has affected principally the Northern and Southern districts of the Tampico area; in December the Northern district (Panuco) was producing less than zoo0 bbl. per day with 445 wells shut down and the Southern district (GolJen Lane) less than $000 bbl. per day with 140 wells shut down. Drilling.—During the year 14 wells were drilled in Mexico, of which five were productive. Seven dry holes were drilled in Ebano, Tampico Northern district, in search for new producing fractures; plans are being made to explore this area by means of resistivity measurements. Three producing wells were completed in Poza Rica. Drilling in this important field will continue during 1943 to determine its extension to the west. In the Isthmus of Tehuantepec no wells were completed. Two gas wells were completed in northeastern Mexico. Wildcats.-—Two wildcat wells were completed during the year, to test the extension of the Golden Lane to the south; both were unproductive. In the Isthmus a deeper sand was found in the El Plan field* This discovery has made an important increase in the reserves in this field and will allow an increase in the production of the area during 1943. In December, three exploration wells were being drilled, two in the Tampico area and one in the Isthmus. Operating Technology.— Satisfactory progress has been made in Mexico in the application of petroleum engineering to the development and operation of the oil fields. Mud control is now an established practice and has lessened the number of fishing jobs and has allowed more open hole to be carried than formerly was possible. During 1942 the first effective use was made of determinations of bottom-hole pressure, and other modern production practices such as gun-perforating and squeeze-cementing are being introduced. Plans for 1943 The oil production during 1943 is expected to be slightly larger than that of 1942, especially if tankers are available for exporting crude and refined products. The Government proposes to increase exploration and drilling activities to increase the reserves and potential production of the country; about 50 wells will be drilled during the year, including wildcat wells in northeastern Mexico, Tampico and Isthmus areas and exploitation wells in the Ebano-Panuco, Poza Rica, El Plan and Cuichapa fields. Acknowledgment Mr. A. Barnetche, of the Production Department, "Petr6leos Mexicanos," assisted the writer in the preparation of the statistical data.

Jan 1, 1943

By Luis Elek

DEVELOPMENT of the cement industry in Mexico began some 40 years ago. It has gradually reached great importance in the economic life of the country and has contributed greatly to the technical and economical advances which have been so noteworthy, particularly during the last 15 years. From a modest start, the industry now comprises 18 cement-producing plants having a potential annual capacity of approximately 14 million bbl. About half the plants were built and equipped with second-hand machinery during the last world war when no new machinery could be procured. They will hardly attain full production before being modernized and reconditioned, a job now under way in several of the plants. At present, the yearly consumption is only about 8 to 9 million bbl but is steadily increasing. This is only a fraction of the cement consumed in the U.S.A., which is about 250 million bbl per year, although on the basis of consumption per capita per year, the figure is 1/3 bbl for Mexico and 1 2/3 bbl for the U.S.A. Cement consumption in Mexico is well above the average of all other Latin American countries, with the exception of the Argentine, and considering the potentialities and undeveloped riches of Mexico, the road construction and irrigation works, it is fair to assume that the Mexican cement industry will still prosper and expand in spite of temporary setbacks in the future caused by-local events of economic or political nature. Portland cement is manufactured by burning a mixture of raw materials, one of which is mainly composed of calcium carbonates and the other of aluminum silicates. The most typical materials answering this description are limestone and clay, both of which occur in Mexico in many varieties. To be usable for cement manufacture limestone should contain at least 77 to 80 pct calcium carbonate. Lower grade limestone can be used for cement manufacture only if the lime content is increased by the beneficiation process, which has not yet been adopted by the Mexican cement industry. Most of the limestone used by Mexican cement plants has a calcium carbonate content of 90 to 95 pct and therefore requires addition of one or several correction materials. A typical composition of raw mix for cement manufacture is 85 pct limestone and 15 pct shale, clay or volcanic materials. Occasionally it is necessary to add a smaller amount of sand or other siliceous material to increase the silica ratio in the raw mix. Likewise, it is sometimes necessary to add 1 or 2 pct iron ore to facilitate fusion in the kiln and to obtain proper relation between alumina and iron oxide. After calcining and

Jan 1, 1952

By J. M. De La Garza Cárdenas

The total production of oil in Mexico in 1942 was 34,715,547 bbl.; that is, 8,179,254 bbl. less than the amount produced in 1941. The daily average for 1942 was 95,111 bbl., while that for 1941 was I17,520 barrels. The reduction of 22,409 bbl. per day in production was due to a decrease in exports because of the scarcity of tankers. This reduction has affected principally the Northern and Southern districts of the Tampico area; in December the Northern district (Panuco) was producing less than zoo0 bbl. per day with 445 wells shut down and the Southern district (GolJen Lane) less than $000 bbl. per day with 140 wells shut down. Drilling.—During the year 14 wells were drilled in Mexico, of which five were productive. Seven dry holes were drilled in Ebano, Tampico Northern district, in search for new producing fractures; plans are being made to explore this area by means of resistivity measurements. Three producing wells were completed in Poza Rica. Drilling in this important field will continue during 1943 to determine its extension to the west. In the Isthmus of Tehuantepec no wells were completed. Two gas wells were completed in northeastern Mexico. Wildcats.-—Two wildcat wells were completed during the year, to test the extension of the Golden Lane to the south; both were unproductive. In the Isthmus a deeper sand was found in the El Plan field* This discovery has made an important increase in the reserves in this field and will allow an increase in the production of the area during 1943. In December, three exploration wells were being drilled, two in the Tampico area and one in the Isthmus. Operating Technology.— Satisfactory progress has been made in Mexico in the application of petroleum engineering to the development and operation of the oil fields. Mud control is now an established practice and has lessened the number of fishing jobs and has allowed more open hole to be carried than formerly was possible. During 1942 the first effective use was made of determinations of bottom-hole pressure, and other modern production practices such as gun-perforating and squeeze-cementing are being introduced. Plans for 1943 The oil production during 1943 is expected to be slightly larger than that of 1942, especially if tankers are available for exporting crude and refined products. The Government proposes to increase exploration and drilling activities to increase the reserves and potential production of the country; about 50 wells will be drilled during the year, including wildcat wells in northeastern Mexico, Tampico and Isthmus areas and exploitation wells in the Ebano-Panuco, Poza Rica, El Plan and Cuichapa fields. Acknowledgment Mr. A. Barnetche, of the Production Department, "Petr6leos Mexicanos," assisted the writer in the preparation of the statistical data.

Jan 1, 1943

By George S. Rice

THE wide scope of the causes and effects of ground movement and their interrelation to various kinds of mining and geological conditions are not always understood. Minimizing of roof movement by selection of suitable mining methods is closely allied to the problem of obtaining maximum safety in mining, but there are other questions involved: for example, mechanical developments which increase the production of ore and other minerals per shift or unit of labor but which, though highly ingenious, may increase hazards. More- over, the newer mobile loaders need much space for operation with longer protecting roof spans. Another problem emphasized by mechanization is the incompleteness of extraction of mineral, as there is no governmental requirement (except for limited leases on the public domain) in this country, as in European countries, and loss of coal in pillars is accepted by mine operators rather than risking the loss of an ex- pensive loading machine from a heavy roof fall. The extent to which losses of coal in mining are now being incurred is conjectural, for it has been fifteen years since there has been a comprehensive survey. In that study a loss of slightly over one-third of the coal in both anthracite and bituminous mining was indicated.

Jan 1, 1939

By R. S. Christie

Reservoir pressure is the pressure at which a fluid is held in a state of equilibrium in a porous stratum. This pressure may be a result of the genesis of oil or gas and its subsequent migration into and through an adjacent porous stratum, or of hydraulic head. Reservoir pressure is an indication of the potential energy contained in the reservoir, and when it is known the engineer is in a position to use it to advantage in recovering and lifting the oil. It is important to know the pressures in any type of reservoir, but this knowledge is probably of greater value in a limestone reservoir, as at Hobbs, where producing rates or conditions may be more sensitive to changes in pressures. The Hobbs field is in east central Lea County, New Mexico. The discovery well was completed by the Midwest Refining C I. in 1928, but intensive development did not begin until after the completion by the Humble Oil and Refining Co. of No. 1-A Bowers in February, 1930. There are 143 producing wells on approximately 5500 acres. The field has not been defined to the northwest, but a projection of structural contours indicates that the productive area ultimately may cover 7500 acres. The producing horizon is the White or Crystalline lime of Permian age. The top of the lime is found at an average depth of 4000 ft. and the wells penetrate it an average distance of 200 ft. The main pay zone is an oolitic stratum about 25 ft. below the top, and varies from 2 to 15 ft. in thickness. Other porous or cavernous strata are found lower in the lime but have little saturation. The initial production varied from 100 to 25,000 bbl. per day, depending perhaps to some extent on the structural location but chiefly on the porosity of the pay. The initial gas-oil ratio varied from 325 to 16,000 cu. ft. per barrel. In wells where the top of the White lime was found below 350 ft. below sea level (Fig. 1)) the gas-oil ratio was usually less than 1500 cu. ft. per barrel, while in wells higher than 350 ft. below sea level, the ratio was usually above 2000 cu. ft. per barrel. The water table has been determined at about 620 ft. below sea level, by three wells on the west side of the field. With few exceptions, the wells have been completed with 7-in. casing cemented

Jan 1, 1932