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By Howard H. Fields

Any mining engineer with a desire to operate independently, with some financial backing, and with no fear of heavy responsibility and long hours, should be able to make a comfortable living in Mexico. Barring a few inconveniences such as a lack of satisfactory liability or accident insurance, the difficulty of obtaining repair parts or vehicles, and the length of time required to receive returns from shipments, the operation of small mine is not at all difficult. It is, in fact, a little easier to find a good prospect in Mexico than in the U.S.

Jan 1, 1950

By C. K. Leith

1 apologize for attempting to talk in a field in which 1 am by no means a specialist, but some of the problems brought up have much in common with other minerals. It touches the field in which we are all interested and it is a field in which our Mineral Inquiry has been giving special attention during the last two years. While it is the primary business, of course, of this Institute to consider the physical facts and technology of minerals, we now face the necessity of considering the minerd industry in its broader economic, social, and political relationships. We have run into a traffic jam—as though a load of hay had been spilled on the road. It makes no difference whether we are drivers or passengers, technical or nontechnical men, we have to get the load off the road before we can go farther. We are conscious of very many difficulties which are outside of the ordinary range of cost accounting or methods of mining or the usual thing with which we concern ourselves. We have extensive readjustments to make in our social and economic and political contacts. It is up to us to find out what is the matter. As a matter of fact, we do not know what is the matter in any comprehensive way. We have many suggestions as to difficulties here and there. Many people are working on the problem, but when the mineral industry as a whole is asked what is a reasonable course of procedure, what is its program, what would be a reasonable state or national policy, I think you will agree with me that we have no spokesman able to outline even a semblance of such a general policy. We sit back and criticize when somebody else steps in, as Governor Murray stepped in, and as many others of our state governors and legislators are stepping in, to do things which we do not think are reasonable. When they say, "What is a reasonable program? " we find ourselves caught napping. We have not agreed on a program. The other day in talking with one of the leaders of the western radical movement, I was twitting him on having no sound and comprehensive conservation program. He said, "What is yours, and what is the program of the mineral

Jan 1, 1932

A completely automated primary crusher is now in operation at Kaiser Steel Corp.'s Eagle Mountain, Calif., iron mine. The word "completely" is italicized to underscore its literal meaning- automation so thorough that even the control room for the crusher does not require a man to watch the flickering dials and lights. The automation of the unit is such that its operation, including starting and stopping, are controlled from the secondary crusher station. The crusher-a Symons 60-in. gyratory which can handle 3600 tph-features built-in safety devices that will turn the crusher off if oil pressure drops, if oil overheats, if bearing temperatures exceed permissible limits, or if parts of its electronic brain fail. According to reports, the worst that can now happen is a plugging of the crusher.

Jan 6, 1963

By T. A. Rickard

The writing that is effective is woven with a fine texture into an agreeable pattern; it is free from knots, loose threads, and stray fluff. The instrument that weaves this literary fabric, whether it produce a homely sock or a lordly tapestry, a simple story or a learned 'Itreatise, is a disciplined intelligence, as sure as a steel needle, as precise as a swift loom. The simile breaks down at this point, for the product of the pen is instinct with the human spirit and therefore transcends in beauty anything made by a mere machine. If words are to be woven into eloquent meaning, they must be well knit. Upon the relation of words to each other and of groups of words to other groups, known as phrases, clauses, and sentences, depends the success of writing as a means of trans¬mitting thought from man' to man. To be understood beyond question, you should know not only what your words denote but how to build your sentences; you must not only choose your words aright but construct your sentences properly. A sentence is a combination of words that makes complete sense; it says something about something. ' A clause is a subordinate sentence or a sentence within a sentence. A phrase is a group of words without a predicate; it makes sense, but not complete sense. For example: I shall wait for a few minutes before I go home: The whole statement is a sentence; "I shall wait" and "before I go home" are clauses; "for a few minutes" is an adverbial phrase. The orderly arranging of words and of combinations of words is called `syntax'; and from the original Greek form, ouvaeis (suntaxis), is derived the Greek name for an editor,

Jan 1, 1931

By Theodore H. Eyde

In the southwest porphyry copper province, the virgin prospect with good copper mineralization cropping out has disappeared. Future discoveries will require an increasingly sophisticated arsenal of exploration techniques and concepts. One of the latter, stratigraphic analysis, is a technique which is often overlooked. A surprising number of exploration geologists still think of porphyry copper deposits as occurring wholly within intrusive bodies such as quartz monzonite or granodiorite. Disseminated copper mineralization, though genetically related to intrusive rocks, can occur within both the intrusive and the intruded rocks. At present, as much as 30% of the total copper produced from disseminated copper deposits in the Southwest originate from the intruded rocks rather than the intrusive.

Jan 4, 1972

By W. B. Plank

The figures on enrollment in the engineering schools of the United States and Canada indicate that the total number of students in these schools for the current year, 1949-50, is about 10% less than it was a year ago. This year, 226,533 undergraduates and graduate students are studying engineering in the United States and Canada as compared with 249,913 students last year. These figures are taken from advance data in the Journal of Engineering Education for February 1950.

Jan 5, 1950

By R. L. Sebastian

ALUMINUM'S war history is the record of a successful race to expand facilities fast enough to meet the multiple increases in military requirements, principally for aircraft. From the beginning of the war program in 1940 through 1942, requirements estimates were repeatedly lifted to new high levels, and plans for increasing capacity had to be constantly revised. In 1943, basic metal supply caught up with and exceeded requirements, and by 1944, the surplus of primary production was large enough to force reduction in output and plant closings. In the past two years, ingot capacity has been ample, though periodic critical shortages have been experienced for a few fabricated shapes as a result of sudden shifts in demand. And now with all controls lifted we are faced with surplus capacity, surplus stocks, and surplus scrap. In 1938 the Aluminum Co. of America was the only U. S. producer of primary

Jan 1, 1946

The fundamentals of blasting involve both the properties of explosives and of the rock being blasted. Four of the most important explosive properties appear to be energy density, bulk density, rate of energy release and the pressure- time history of the gases produced. Important rock properties are density and porosity, strength, and energy absorption including the effective moduli of elasticity. Rock structure also has a marked effect on its properties: for example, joints, bedding, and fracture alteration. Several mechanisms enter into rock fragmentation by blasting. These include slabbing, radial fracturing, crushing and bursting by the gas bubble. All of these factors are closely related to properties of both explosives and rock. Slabbing depends upon the first generated stress wave, whose shape and magnitude are a result of the pressure generated by the explosive, its time history and the resultant response of the rock, including its ability to sustain the stress wave. Actual slabbing, in turn, is a function of the magnitude and shape of the pressure pulse and the tensile strength of rock. Further fragmentation depends to a great extent upon the amount of gas in the bubble and its energy and pressure.

Jan 10, 1967

Cortez Gold Mines operated a conventional 2,100 mtpd (2, 300 stpd) cyanidation plant until the 5 million ton ore body was worked out in 1973. (See Gold and Silver Cyanidation Plant Practice by F. W. McQuiston, Jr. and R. S. Shoemaker, Society of Mining Engineers, AIME 1975.) Sub-grade material was dump leached at the mine -mill location in 1971, and the resulting pregnant solutions were added to the feed in the plant's Merrill-Crowe precipitation unit for gold recovery. In early 1973, however, Cortez put into operation their Gold Acres mine which was located about 13 krn (8 miles) to the west of the 'Cortez mine. Economics at that time dictated the heap leaching of the lower grade portion of the ore body with the higher grade being trucked to the Cortez plant for milling. Leach ore was moved directly from the open pits to prepared leach pads located on a gently sloping terrain of 570 grade. Preliminary pad preparation at the leach site included removal of vegetation which was composed of sagebrush and grading of the base. Pads were comprised of mostly minus 74 micron (200 mesh) materials and were made of clay-silt or slime tailings spread on the pad area in thin 50 to 75 mm (2 to 3 in. ) layers, compacted with a vibrating roller compactor to a depth of about 380 mm (15 in.). This was followed with a 100 mrn (4 in.) layer of coarse rock to prevent erosion on the pad and to allow solutions to move laterally under the heaps. Leach solutions normally traveled the length of the heaps and were collected in plastic-lined ditches from which they flowed by gravity to the pregnant solution storage pond. Both pregnant and barren ponds were constructed in the same manner as the leach pads - being lined with compacted tailings or clay silts. The Gold Acres facility required pregnant solution storage of 6 million liters (1.6 million gal) and barren storage of 3.8 million liters (1.0 million gal) designed to handle two to three days of heap drainage or to retain run-off from a major rainfall. Various heap heights were tried including 3, 6, and 9 meters (10, 20, and 30 ft), with a 6 m (20 ft) height selected. Ore was dumped by trucks in a single 6 m (20 ft) lift using a D8 Caterpillar dozer for

Jan 1, 1981

By Frederick Prime

In this supplementary list no titles to which an * is prefixed have been seen by the compiler; and he will be most thankfu1 to have any omissions or inaccuracies in the list sent to him to be published as a second supplement in the next volume of the Transactions. The author is indebted to Messrs. Robert Clarke, of Cincinnati; Thomas Macfarland, of Towanda; Professor F. W. Simonds, of Chapel Hill; and Professor J. J. Stevenson, of New York, for valuable assistance. Cedar Point IRON Company, Baltimore, July 31st, 1880. Alabama. Geological Survey of Alabama. Report of Progress for 1877 and 1878; by Eugene A. Smith, State Geologist. Montgomery, 1879. 8vo., 139 pp., and 4 maps.

Jan 1, 1880

At its meeting on February 21, 1933, the Board of Directors passed the following resolution defining and expressing the policy of the Institute with respect to official participation or action in controversial matters: WHEREAS, the Board of Directors at its last meeting passed the following resolution : "The Board of Directors, having been appealed to by several Local Sections for advice concerning the attitude and policy of the Institute relating to the endorsement of candidates for public office, the following statement of policy is formulated: "Whereas, the American Institute of Miming and Metallurgical Engineers is organized for purely professional and scientific purposes, and whereas diversity of opinion among its members on partisan or political questions is inevitable, it is the ex- pressed policy of the Institute to refrain from official participation or action in political and semi-political matters."

Jan 1, 1946

Gentlemen.-The Institute was founded 54 years ago "with the object of promoting the arts and sciences connected with the economic production of the useful minerals and metals and the welfare of those employed in these industries by means of meetings for social intercourse and the reading and discussion of professional papers, and to circulate by means of publications among its members and associates the information thus obtained," At least once a year it is well to take stock of our assets, review our performance and determine how well we are now carrying out the purposes of our Founders. There can be no question as to the work the Institute has done and is doing in promoting the arts and sciences in the fields of mining and metallurgy. One needs only to contrast the methods, the labor and the costs of a half century ago with those now to visualize how far we have gone in the development of accurate technology and sound economics in mineral and metal production. The great mines, mills and smelters of the present, handling individually thousands of tons per day, would' have been impossible except for the accumulation of knowledge, the development of theory, and the improvement in practice that has characterized the period since the foundation of the Institute. The United States has prospered in the last half century greatly, and this has been due not merely to the possession of great natural resources, but to these resources being reduced to possession and put to work. The absence of customs barriers and the freedom of trade across the whole width of this great continent has been an important factor in the growth of our wealth. Unrestricted interchange of goods has permitted each citizen to draw on the resources of the whole country. However, these are but subsidiary causes of prosperity. The free interchange of scientific and technical data, by making the whole body of facts and theory available to each worker, has made this quick and unrivaled development possible. In promoting this free trade in knowledge the Institute may claim a large place without fear of denial. The .72 volumes of TRANSACTIONS, the special volumes, the bulletins and the other publications that have been issued, include a store of knowledge of the arts and sciences related to the production and use of metals and minerals not duplicated elsewhere. The large list of foreign members-1746 in number-few of whom ever have opportunity to attend meetings and all of whom derive their main benefits from membership through the pub-

Jan 1, 1928

By Leo Greenberg

As one of its functions, the U.S. Bureau of Mines gathers and analyzes mine accident data, and then publishes annual reports on work injury experience in the various segments of the minerals industry- coal, nonmetals, rock. These reports contain a wealth of detailed data, with a multitude of analyses and cross-tabulations, all intended to shed as much light as possible on accidents and to suggest possible ways of reducing them. In this article, the terms, "injury" and "accident" will at times be used interchangeably to denote accidents which cause disabling injury. The Bureau bases many of its analyses on American National Standard Z16.1 for recording and measuring work injury data. This document establishes two models for measuring disabling injury experience: (1) the frequency rate, obtained by dividing the number of man hours into the number of injuries multiplied by 1 million, and (2) the severity rate, similarly constructed, with the variable of interest being the number of days lost due to these injuries. Similar computations are performed by the U.S. Bureau of Labor Statistics and the National Safety Council. Additionally, these models are used in many other countries, sometimes with minor changes.

Jan 1, 1971

THE LIFE and works of Alexander Agassiz, first president of the Calumet & Hecla Mining Co., were recalled to memory when a monument bearing his statue was unveiled in Agassiz Park, at Calumet, Mich., on Sept. 26, The statue is the work of Paul W. Bartlett, of New York, and was erected by George R. Agassiz, eldest son of Alexander Agassiz. We are indebted to Rodolphe L. Agassiz, now president of the Calumet & Hecla Consolidated, for the accompanying photograph of the statue. The principal address at the unveiling ceremony was delivered by Allen F. Rees, of Houghton, who said, in part: To the world at large Alexander Agassiz was preeminently the man of science. With all his devotion to the industrial life of this district, he found the time to devote to the con-tinuation of his work of scientific research which had been the life work of his fa-ther, Louis Agassiz. Not only did he acquire eminence for his scientific at-tainments and learn-ing, but he was recognized and hon-ored throughout the civilized world for his achievements and accomplishments in the realm of original research. His work in the fields of nat-ural science, in oceanography, in marine zoology, and in other similar lines of research, has added much to our knowledge of the world's mysteries. His life was one of accomplishment also in the industrial world. The union in one life of acknowledged achievement as a scientist and the accomplishment of great results in the prac-tical industrial world is a rare thing, and its possibility has never been exemplified in greater measure than in his life and its results.

Jan 11, 1923

By R. J. Mechin

TOP-SLICING was introduced in the Pachuca district in 1917 by T. C. Baker, at that time mine superintendent, of the Santa Gertrudis mine. There then existed 1200 ft. (365.7 m.) below the surface, lying between the fourteenth and eighteenth levels (a vertical distance of 108 meters) a block of ore having a length of 295 ft. (90 m.), and an average width of 82 ft. (25 m.) and dipping at an angle of 65°. This block lay in the hanging wall of the vein and consisted of highly altered and fractured andesite, cut through with mineralized quartz stringers. On the foot-wall side, 26 ft. (8 m.) of old filling, left by former operators, was of payable grade. Stoping therein was first undertaken by the square-set filling system, but because of the extremely heavy hanging wall and loose dry filling in the foot wall, all square setting had to be accompanied by spiling, which made the operation exceedingly slow and costly. A system of mining was sought that would eliminate the difficulties inherent to the square-set system in heavy ground and that at the same time would effect the desired economies in mining. After several years, top-slicing has met all the conditions most satisfactorily, so that when similar conditions presented themselves in El Bordo mine, this method was adopted with necessary modifications. El Bordo mine is operated by the Santa Gertrudis company, and is situated about two miles north of Pachuca. Because of the diversity of the orebodies, a number of different mining methods are in use, among them top-slicing.

Jan 10, 1925

By FLOYD T. TAYLOR

IN 1833, less than one hundred years ago, Michael Faraday discovered and stated the laws of electrolysis. His discovery formed the foundation of a new use of metals which has now reached a variety of application not ordinarily appreciated. Furthermore, things can be done with electro-deposited coatings which have thus far defied other methods. Some of the uses of electro-deposited coatings are interesting. The tonnage of metals already finding an outlet through such a channel is considerable. In general electro-deposits have two characteristics: ornament plus utility; utility plus ornament. Both these factors are usually found associated in electro- deposits. Ornament plus utility was probably the first use. For example, the silver-plating of tableware, having its real birth in Birmingham, England, about 1844. However, this same ornament plus utility retarded the development of electro-plating, because in the beginning, electro-plated articles were branded with the odium of imitation and shunned accordingly. The gold brick of the swindler may be an exception to this statement.

Jan 1, 1929

By Thomas T., Read

THE education of adolescents to perform the duties and assume the responsibilities of maturity has been a characteristic of human society since the dawn of history. In the beginning the members of the immediate family performed this function, and in modern life they still have an important part in it. Possibly religion was the first field in which education began to be functional; young people were sent for instruction to a teacher who had a broader and deeper knowledge of the subject than was possessed by the family. It does not seem necessary for our purpose to attempt to determine how, when, or where instruction in the practical arts first' began to become functional, and the brief outline which follows must suffice. The discovery and utilization of mineral substances to improve and maintain the conditions of human living is a practical art, which must have had an almost accidental origin and have been developed by empirical experiments. We do not know, nor would it be useful to try to fancy, how men first learned that they could make use .of mineral substances to their benefit, but how- ever that knowledge was initially gained it was certainly trans mitted through instruction in the family. At first such activities must have been merely a .minor part of the making of a-living, but in time those who excelled found it better to devote them-

Jan 1, 1941

By George A. Laird

I. INTRODUCTION. THIS old and once famous district played, through its enormous production of silver and gold, an important part in the history of the State of San Luis Potosi. According to a pamphlet prepared under the direction of the Governor of the State, Sr. Don Blas Escontria, and presented to the visiting members of the Institute during the Mexican meeting of 1901, this district is situated 20 km. east of the city of San Luis Potosi, in a range of mountains of moderate height, extending 135 km. N. and S., and 16 km. E. and W.; and the mineralized area hitherto developed is about 600,000 sq. m. The history of the district,. as given by the record dated 1778, and formerly kept in the San Francisco convent, says that it was discovered in 1575 by Sr. Don Pedro Irarte, and adds that the city of San Luis Rey de Francisco del Potosi received its name (in allusion to the famous Potosi mines in Bolivia) by reason of the remarkable productiveness of its gold- and silver-mines in the first period of their exploration, during which they paid to the Crown, as " quintos " (the fifth part of the product), $97,000,000, as appears from the accounts of the royal treasury. The amount of the quientos paid during the " bonanza period " of 80 years was $72,000,000. The larger sum first mentioned probably represents a longer series of years. But either will suffice to indicate the great wealth of the mines. In 1663, the decadence of the industry began with the caving¬ in of several mines, concerning which the record of 1778, al¬ready cited, says, in substance, that on Good Friday one of the owners in the enterprise, in view of the unfavorable prospect of a lawsuit in which he was engaged, set fire to the timbers supporting the underground galleries and workings of the San

Jan 1, 1905

By L. S. Darken

IN the study of reactions occurring in liquid iron, alone or in contact with a liquid oxide or slag phase, it has been found that the experimental data over a limited range of concentration can in some cases be repre-sented satisfactorily by the simple equilibrium expression K - (p1)p1 (p2)p2 . (R1)r1(R2)r2 . where (P) denotes the concentration of a product and (R) the concentra-tion of a reactant in the reaction r1R1 + r2R2 + . . . Some of the reactions for which it holds are listed in Table 1. For others, however, the simple equation apparently does not hold. This has been attributed to an improper method of expressing concentration (for instance, weight per cent instead of mol fraction); or it has been supposed that the solutions are not ideal in the sense that the activity of a com-ponent is not proportional to its true mol fraction, But it may be that the problem has been oversimplified by neglecting some molecular species actually present; that is, by considering only the ostensible simple com-ponents and thus leaving out of account possible compound formation. It is the purpose of the present paper to point out how, in a group of related cases, a reasonable consistent assumption relative to the presence of a compound makes it possible to express the experimental data satis-factorily by the simple equilibrium expression when this compound is taken into account, and to bring into harmony data referring to different reactions in liquid iron. There are several a priori reasons for believing that solutions in liquid iron should not deviate far from ideality, provided that the concentration of solute is not too great and is expressed in proper terms. The factors that commonly lead to nonideality in systems at ordinary temperature as ionization or the occurrence of polar and nonpolar molecules-are presumably less effective in metal and in slag systems at high temperature. Again, the type of equation commonly used to express the value of

Jan 1, 1940

By K. H. Heino

Two 200 T/da Lurgi Turbulent Layer fluid-bed roasters have been in operation at Canadian Electrolytic Zinc Limited since 1966. Zinc concentrate containing 52-54% Zn, 9-11% Fe,31-33% S is treated to produce calcine containing 60-62% Zn,10-12% Fe, .l-.3% S as sulphide and .8-1.2% S as sulphate. Each roaster train comprises a waste heat boiler, two cyclones in parallel and a two-field electrostatic precipitator. Distribution of calcine collected is 10-15 percent from bed overflow, 55-65 percent from boilers, 20-25 percent from cyclones and 2-6 percent from precipitators. A Monsanto designed contact plant produces acid at a rated capacity of 365 T/da (100% H2304 basis) from roaster gases diluted to 7.0-7.5% S02. The process steps are gas cleaning and cooling by weak acid scrubbing, acid mist removal in electrostatic precipitators, gas drying in 93.5-96.5% H2304, conversion of sulphur dioxide to sulphur trioxide in a four-pass converter containing vanadium pentoxide catalyst, and absorption of the sulphur trioxide in 98.1-98.3% H2S04. Product acid is 93.2% H2S04. Conversion efficiency is 97-98 percent and overall sulphur recovery from concentrate is 87-90 percent. The adjacent fertilizer plant has a capacity of 135 T/da of P205. The products are 54 percent phosphoric acid, run-of-pile triple superphosphate, and diammonium phosphate. The plant is of Ugine-Kuhlman design and consists of an air-cooled multiple tank reactor, a tilting pan filter, and a forced circultation vacuum evaporator. Triple superphosphate is made on a continuous belt and partially cured in a rotary dryer. Diammonium phosphate is produced by ammoniating phosphoric acid in a single stage reactor. The slurry of ammonium phosphate is granulated in a blunger and dried.

Jan 1, 1970