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By D. C. Jillson

THE data on the critical resolved shear stress for zinc single crystals published by Rosbaud and Schmid1 showed many irregularities, as seen in fig. 1. There have been subsequent investigations,2,3 but no one has repeated this work with a wide range of orientations, with specimens of a higher degree of purity and perfection, and with improved experimental techniques in order to determine whether these variations were entirely experimental or whether they might have been due, at least in part, to some feature of the mode of deformation not known or understood. Mathewson4 and others have long felt that the glide observed in a [100]* direction between two (001)* planes in the zinc lattice might be actually the net effect of many consecutive unit glides or movements in two alternating [210] directions (fig.

Jan 1, 1951

By Gilbert Thiessen

THE purposes of this paper are (1) to show that the mineral matter content of coal is satisfactorily represented by the Parr formula; that is, Mineral matter = 1.08 Ash + 0.55 Total sulfur (2) to compare ash-to-mineral-matter ratios with factors by which ash values must be multiplied in order that dry, factor-times-ash-free values shall equal Parr unit coal values; (3) to examine such ash-correction factors and to compare them with similar factors corresponding to certain simplifications or modifications of the Parr formulas and (4) to show that ash-correction factors used for simplification in calculating approximate unit coal calorific values cannot be. correctly used for the conversion of other determined values in an analysis to the unit coal basis, but that each type of calculation requires separate treatment in simplification.

Jan 1, 1934

By D. G. Peterson, W. J. Guay

The extraction of gold from refractory ores containing activated carbon and various types of carbon compounds is being done commercially for the first time at Carlin, Nev., by Carlin Gold Mining Co. Oxidation of the carbonaceous materials to CO and CO,- is accomplished by the introduction of chlorine into an aqueous pulp. The chlorine reacts with the limestone in the ore to form calcium hypochlorite which in turn reacts with the carbonaceous matter to form calcium chloride, CO, and CO.. Following the oxidation treatment the ore is cyanided in the conventional manner. For the first six months of operation the plant averaged 83% extraction at a feed rate of 500 tpd and a consumption of 28.4 lb chlorine per ton of ore which showed only 33.5% extraction by conventional cyanidation without the oxidation pretreatment.

Jan 1, 1974

By Alden B. Greninger

The study of mosaic structure of crystals1 has been confined until recently to the field of theoretical physics. Crystallographers, in general, have neglected the subject, although X-ray crystallographers constantly make use of formulas for intensities of X-ray reflection as modified by mosaic structure. Work on mosaic structure has centered chiefly on the task of proving or disproving the secondary-structure theory of Zwicky,² and very little attention has been paid to the visible imperfections of crystals. A. Goetz has been responsible for most of the supposed experimental confirmations of Zwicky's theory.3 On the other hand, Smckal,4 and Orowan,5 among others, maintain that there is neither theoretical nor experimental evidence to substantiate Zwicky's secondary structure. Lately the subject has been intensively investigated by Buerger,6 one of whose recent papers led to a symposium on mosaic structures.'

Jan 1, 1935

By Alden B. Greninger

The study of mosaic structure of crystals1 has been confined until recently to the field of theoretical physics. Crystallographers, in general, have neglected the subject, although X-ray crystallographers constantly make use of formulas for intensities of X-ray reflection as modified by mosaic structure. Work on mosaic structure has centered chiefly on the task of proving or disproving the secondary-structure theory of Zwicky,² and very little attention has been paid to the visible imperfections of crystals. A. Goetz has been responsible for most of the supposed experimental confirmations of Zwicky's theory.3 On the other hand, Smckal,4 and Orowan,5 among others, maintain that there is neither theoretical nor experimental evidence to substantiate Zwicky's secondary structure. Lately the subject has been intensively investigated by Buerger,6 one of whose recent papers led to a symposium on mosaic structures.'

Jan 1, 1935

By Edwin H. Olson, Morton Smutz, Charles J. Baroch

IN 1949 an orebody containing some 10 billion lb of recoverable rare earth metals was discovered in the Mountain Pass district of San Bernardino County, California.1 The following year Molybdenum Corp. of America purchased a number of claims at the deposit and a mill on the property which had been constructed to process the district's gold ores. Average composition of ore from the San Bernardino deposit is less than 0.1 pct ThO2, 25 to 35 pet calcite, 10 pet rare earth oxides, 15 to 20 pet silica, and 30 to 40 pet barite.2 Rare earth content of the ore analyzes 50.7 pet CeO2, 4.2 pet Pr6O11, 11.7 pet Nd2O3, 1.3 pet Sm2O3, and 34.3 pet La2O3, and others.2

Jan 3, 1959

By Robert D. Gunn, John E. Boysen, Dennis D. Fischer

The second underground coal gasification experiment conducted by ERDA's Laramie Energy Research Center at a site near Hanna, Wyo., was completed on Jul. 30, 1976. During the experiment production reached 0.32 blm3/d (12 M cu ft/d) of 6.9 w/m3 gas (175 Btu per cu ft). Approximately 6100 tonnes (6700 tons) of coal were gasified during the experiment. Energy return ratios of 4.5 to 5.3, coal gas thermal efficiencies of 76 to 89%, and overall process efficiencies of 65 to 74% were achieved during the second Hanna experiment. This paper describes the experiment and the results obtained with emphasis given to the determination of the energy recovered relative to energy consumed in conducting the test. Data from this determination are compared with previously published data from the first test conducted at Hanna during 1973-74.

Jan 1, 1978

JOHN B. HASTINGS, Los Angeles, Cal. (written discussion *).-This, paper is so admirable for its brevity that one hesitates to enter into discussion. The cycle of eruptives makes one wonder, "Where's the basalt?" and the youthfulness of the Idaho flows suggests they may yet come. Veins and Dikes.-Veins and dikes seem to be closely aligned in the minds of some authors, while to me they appear quite distinct, the first representing quiet, long-continued action, typified by metasomatic replacement, far removed from volcanic action; the latter, sudden and cyclonic, emanating from the heart of vulcanism. The rock openings occupied by both types were formed by kindred forces, but in the one they were closed for indefinite periods before invasion by the solfataric solutions, and in the other their formation and occupation were simultaneous. Open Fissures.-I do not believe in the existence of open spaces of discission that may be occupied by veins. Occasionally they occur; I found one with. a machine drill 350 ft. below surface, fortunately in an adit; the water spouted for 12 ft. in a 6-in stream for nearly 24 hr. It was only a flattish fissure, 6 in. wide, crossing the perpendicular vein, and indicating how tabular veins of ore might be formed. The practical absence of open fissures should be a joy to miners. We all know the misgivings with which we feel about for an old winze having only 30 ft. of water in it, in an unsurveyed and inaccessible part of a mine. It is said that veins are sometimes formed in open spaces left by Protuberances of the walls, which meet after having been displaced; but I believe that in such circumstances there would be sufficient attrition and brecciated material to fill the fissure, though perhaps loosely. Parts of veins may possibly have been formed in originally open spaces, but if so, the spaces were made by solution shortly preceding the deposition of the veins. That total solution of rock adjacent to a fissure may occur under favorable conditions is proved by the existence of large bodies of sulphide which contain only a few per cent. of silica; while on the same level, and in other levels above and below, all being within the same ore shoot, assays may show as much as 50 to 60 per cent. of silica, although the gold, silver and copper assays may be almost identical in all the

Jan 1, 1918

By John F. Knudsen

Following the flowsheet from the primary crushing plant of Ray mines division through the final products sample mill, there are eight exhaust systems ranging in size from 12,000 to 30,000 cfm. Where possible, hood face velocities are kept around 500 ft per min, permitting branch velocities of 2500 ft per min. Tight-fitting enclosures are provided over all ore drops, crushing operations, and vibrating screens. All enclosures are exhausted either primarily or secondarily, except those around conveyor head-pulleys where the ejector effect of the falling ore creates sufficient indraft to abate dust dissemination. IN 1947 an Industrial Hygiene Department was organized to represent and assist the four western mining divisions in industrial hygiene problems. Department headquarters are located at the Utah Copper Division, Magna Plant, Magna, Utah, with a branch office at the Chino Mines Division, Hurley, N. M. The headquarters staff includes a director, a department secretary, an industrial hygienist, a supervising ventilation engineer, and two ventilation designers. To be in closer association with work at the Southwest properties, a field engineer at the branch office conducts field studies which include ventilation problems at the New Mexico and Arizona properties;i.e., the Chino and Ray mines divisions. Functions of the department are to discover and evaluate existing hazards and to develop protective measures, either by personal protective devices or by proper ventilation, depending on the nature of the contaminant. Other than dust counting, all air samples collected at the four properties are processed at the home office. If through plant surveys or by suggestion of management some type of ventilation or air conditioning is required, the problem is usually handled by the ventilation section of the headquarters department, where general arrangement or line drawings are prepared, showing hoods, ducting, and equipment. Some hood and special parts detailing is done at headquarters; otherwise, required detailing is done by the respective plant engineering departments. Prior to the design of industrial ventilation, either new projects or the revamping of old ones, a thorough survey is made of existing conditions. In so far as possible weighted average exposures are determined and adequate ventilation provided on the basis of maximum allowable concentrations of the contaminant in question, as well as medical case histories, if these are available.

Jan 1, 1954

By H. C. Fiedler

SILICON-IRON strip with a cube-on-edge secondary recrystallization texture is made commercially as thin as 10 mils. With inclusions present to inhibit normal grain growth, a few grains, and these have the (110)[001] orientation, grow very large at the expense of the matrix grains. In the absence of inclusions, only normal grain growth occurs and the texture is not as strong as when it is developed by secondary recrystallization.1 Strip for use at frequencies of 400 cps and higher is made in thicknesses of 1, 2, and 4 mils by a process developed by Littmann.2 Attempts to develop a strong texture in these thin gages by the same methods as were used for the 10 mil and thicker strip were unsuccessful,2 and Littmann's solution to this problem was to cold roll the grain

Jan 1, 1963

By Knut L. Sandvik, Aage Solbakken

it is an established fact that the collecting properties of xanthates and anionic collectors are dependent on the hydrocarbon chain length. This is ascribed to the greater adsorption densities caused by increasing the xanthate chain length. As batch flotation tests showed similar trends for amines, an investigation of the adsorbing properties of amines was undertaken. Because earlier investigations showed adsorption densities for dodecylamine salts on quartz varying as much as 20 times under apparently similar conditions,1-4 it was decided to make a survey of the changes in adsorption density due to the drying conditions of the quartz. EXPERIMENTAL PROCEDURE The quartz, handpicked in the pegmatite quarries of Iveland, Setesdal, had the following composition: SiO2 99.81, A12O3 0.01, Fe2O3 0.05 and loss by ig-

Jan 1, 1969

By Michael B. Kahle, Fred J. Scheaffer

Production scheduling, along with production planning, provides projections of future mining progress and time requirements for the development and extraction of a resource. These schedules and plans are used by management as a means of attaining the following objectives (1) maintaining or maximizing expected profit, (2) determining future investment in mining, (3) optimizing return on investment, (4) evaluating alternative Investments, and (5) conserving and developing owned resources. The first four goals are generally concerned with mining costs, both capital and operating requirements, and as such, play an important role in production planning. However, this chapter is concerned with the fifth management objective of resource development in order to conserve and perpetuate the corporate entity. The following discussion is based on the premise that detailed economic evaluations and market surveys have been performed and analyzed and that the results indi¬cate a viable project.

Jan 1, 1979

By A. Wadood M. A. El Rabaa, William A. Hustrulid, William F. Ubbes

The spatial distribution of the deformation modulii around the CSM/ONWI test facility was determined using an NX version of the CSM cell. Approximately 840 modulus measurements were made in six rings (each ring containing seven holes each 6 m in length) of boreholes. These parallel rings were spaced at 2.4 m intervals along the room. Contour plots of the modulii revealed that the depth of the blast damage zone varied both with perimeter position and distance away from the opening. The maximum depth of disturbance appeared to be of the order of 60 cm. At locations removed from the opening, the variability in modulus was quite high reflecting the presence of joints, faults, shear zones and foliation. A comparison of rock mass modulii (ER) with those obtained from the laboratory testing of core (E), revealed that ER [=] 0.5 E.

Jan 1, 1982

By John M. Rayburn

When plans were made for the new mine of the Allegheny-Pittsburgh Coal Co., Springdale, Pa., it was decided to operate on the room and pillar system, but not to have any extensive room development, the pillar work being done altogether on the retreat. On each room heading five rooms were to he driven advancing, while five pillars were being removed, so timed as to form a continuous pillar line, with all approaching

Jan 1, 1930

By George Riter

OUR mineral-land laws need revising so as to provide definite title at the outset to the mineral deposits within any definite piece of land. The laws as they now stand, especially those applicable to lodes, breed uncertainty as to rights of possession prior to patent; and to my mind this is the worst feature of all, worse even than the apex bugbear. It is now almost impossible for anybody to tell with certainty what mineral rights exist within any area that is not covered y patent, or whether any valid rights exist at all. Our system is unique in permitting individuals to appropriate and exploit mineral lands of the public domain without notice of any kind to the Federal government, and to relinquish them without any ceremony at all. The result is a clouded record that cannot be cleared' up until each claimant is put to some sort of final proof. In order to accomplish this, new Federal legislation will be required. The requirements for a mineral survey and the proceedings for patent have always been cumbersome and expensive; and perhaps out of regard for the poor claim owner, who can ill afford the outlay for that sort of thing, the law does not require him to go through it unless he chooses to do so. Consequently, every active mining district has become encumbered with tangled groups of doubtful or conflicting locations, whose rights and boundaries, when any valuable ore is found, must usually be determined by lawsuits that are as expensive and as distressing as the stakes are high. So deeply has litigation entered into our mining system that a claim whose rights have never been disputed would probably be set down offhand, y a miner of the old school, as of no value. Think of the litigation over rights of possession on the Comstock lode-12 leading companies involved in an aggregate of 245 suits within a period of less than eight years! Ambiguous local records; the chance of erroneously placed or obliterated monuments; doubt as to the sufficient performance of the statutory annual labor; uncertainty as to prior conflicting or overlapping locations; anxiety as to the changing attitude of the Department of the Interior and the Forest Service-such considerations as these make an unpatented mining claim an unclean thing in the eyes of possible investors. Is it any wonder that they keep themselves and their money at a safe distance,

Jan 7, 1914

Herbert Moore Harbach was born in Lebanon, Pa., Apr. 4, 1891, graduated from the Lebanon High School in 1911, and entered State College, from which he received his degree of Bachelor of Science in Metallurgical Engineering in 1915. He was employed by the Lackawanna Iron Co., at Buffalo, N. Y., and was later transferred 'to their Lebanon plant to start up the newly erected benzol plant. He was later made foreman of the coke ovens, which position he held after it was bought by the Bethlehem Steel Co., and until he enlisted in the service of his country in September, 1917. He was stationed at Camp Meade, Md., until the spring of 1918, when he was transferred to the C. W. S., at Niagara Falls, as an expert chemist. There he was engaged in perfecting the various kinds of gases,

Jan 2, 1919

By Benny Langston, Frank M. Jr. Stephens

IN recent years much attention has been given to recovery, treatment, and disposal of dusts discharged into the atmosphere from operations of industry. Considerable data has been accumulated on both operational1-4 and design5,6 of dust-collector equipment for commercial installations. On the other hand, there is almost no published data on design and construction of small-scale equipment to handle dust problems that arise in the ore-dressing laboratory. Dust-collection equipment such as multiclones, single-cyclones, scrubbers, chemical and mechanical filters, settling chambers, and electrostatic separators has proved its efficiency for collecting dust in industry. In the laboratory, however, the engineer is faced with the problem of collecting small quantities of dust, inexpensively, without diverting the major effort from the metallurgical problem to the problem of collecting dust produced by the process.

Jan 8, 1954

By Sidney Wise

WHILE the installation of mine bulkheads to retain water under high pressure is y no means a rarity, the following points Which arose in the designing and placing of two of these bulkheads may be of interest: The Hibernia magnetite mine, located about 40 miles west of New York, in the State-of New Jersey, is partly filled with water. This mine is located on an ore lens, the outcrop of which is over a mile long. The ore has been mined from this lens from the surface to a depth of more than 1,500 ft. It was held desirable to- separate the old workings from the new, and to allow the former to fill to the 850-ft. level. Two weak places existed between the new and old workings below this level: namely, a temporary bulkhead on the 10th level and a rock bulkhead of indeterminate thickness on the 16th level. When the matter of allowing the old workings to fill was investigated, the fact was developed that if these old workings were filled, the bulkhead on the 10th level would be subjected to a water pressure of about 50 lb. per square inch, and that 200 lb. per square inch would act on the 16th-level bulkhead. As the above-mentioned barriers were not deemed of sufficient strength to permit of these pressures, it became necessary to design and install new bulkheads. Design As the 16th-level bulkhead was required to withstand a pressure of 200 lb. per square inch, it presented some difficulties. A careful consideration of the various types of mine dams now in use led to the adoption of a design of the form of a truncated wedge. In this, the pressure side of the dam is of greater area than the back, so that the resultant action is similar to driving the wedge. By cutting generous skewbacks in the walls, roof, and floor, this type in reality becomes an invisible arch. The wedge feature tends to compress the materials in the bulkhead, thereby adding to its imperviousness.

Jan 8, 1914

By Sidney L. Wise, Walter Strache

While the installation of mine bulkheads to retain water under high pressure is by no means a rarity, the following points which arose in the designing and placing of two of these bulkheads may be of interest: The Hibernia magnetite mine, located about 40 miles west of New York, in the State of New Jersey, is partly fillcd with water. This mine is located on an ore lens, the outcrop of which is over a mile long. The ore has been mined from this lens from the surface to a depth of more than 1,500 ft. It was held desirable to separate the old workings from the new, and to allow the former to fill to the 850-ft. level. Two weak places existed between the new and old workings below this Ievel: namely, a temporary bulkhead on the 10th level and a rock bulkhead of indeterminate thickness on the 16th level. When the matter of allowing the old workings to fill was investigated, the fact was developed that if these old workings were filled, the bulkhead on the 10th level would be subjected to a water pressure of about 50 lb. per square inch, and that 200 lb. per square inch would act on the 16th-level bulkhead. As the above-mentioned barriers were not deemed of sufficient strength to permit of these pressures, it became necessary to design and install new bulkheads. Design As the 16th-level bulkhead was required to withstand a pressure of 200 lb. per square inch, it presented some difficulties. A careful consideration of the various types of mine dams now in use led to the adoption of a design of the form of a truncated wedge. In this, the pressure side of the dam is of greater area than the hack, so that the resultant action is similar to driving the wedge. By cutting generous skewbacks in the walls, roof, and floor, this type in reality becomes an invisible arch. The wedge feature tends to compress the materials in the bulkhead, thereby adding to its imperviousness.

Jan 1, 1915

1. Healthy and active Local Section or¬ganizations are vital factors in promoting the vigor and growth of the Institute. 2. Activity on the part of Local Sections should be recognized and stimulated by appropriation of funds from the Insti¬tute's treasury; and these appropriations should be as large as is consistent with the relative needs for other activities. 3. As between different Sections, the amount of such appropriations should be based primarily on the extent of activities as reflected in the number and character of meetings held and the attendance of the members at such meetings. 4. In making a request for funds for any year, the officers of a Local Section should submit a report on the printed form approved by the Directors at their meeting on November 19, 1937. 5. A standing Committee on Local Sec-

Jan 1, 1944