Search Documents

A. M. CANDY,* Pittsburgh, Pa.-According to the tables on page 532, the deposit obtained with Roebling cold-rolled steel, and Toucan electrodes contained considerably less carbon and manganese than the original electrodes; whereas very little carbon is lost in the case of the hot-rolled steel electrode. When using the hot-rolled steel electrodes, the metal apparently has a tendency, probably due to greater surface tension, to pass through the arc in larger particles than the other electrode materials. This affords greater protection against oxidation, and thereby prevents much loss of carbon. The larger globules tend to increase the arc fluctuations due to greater partial short-circuiting of the arc. Actual oscillographic records show that with the hot-rolled steel electrodes the current peaks were 70 per cent. above normal whereas the peaks for the other electrodes were only about 25 per cent. -above normal. Probably due to the larger globules, a greater proportion of slag in the electrode was carried into the weld. Some four or five test pieces made with the hot-rolled steel electrodes were all considerably below the tensile strength of the samples welded with the other electrodes. These facts indicate that an electrode may not be satisfactory even though of approximately the proper chemical composition. For example; the hot-rolled steel and Roebling electrodes are quite similar in chemical analysis.

Jan 4, 1919

By C. M. Ball

The magnetic concentration of iron-ores has been so often and so widely studied and discussed among the members of the Institute that any remarks concerning its general importance, from an economic standpoint, would be superfluous; but it is thought that a description of the Ball and Norton ore-separator, designed for cobbing and separating magnetic iron-ores, indicating its essential differences from other machines and the advantages claimed for it, together with some account of recent results obtained in its application to the concentration of such ores, will prove of interest. This machine is the joint invention of Mr. Sheldon Norton, of Hokendauqua, Pa., and the writer, and has been patented in the United States, Canada, and other countries. Of the accompanying illustrations, Pig. 1 represents a longitudinal vertical section of the perfected ore-separator, adapted for separating fine ore, and Fig. 2 the same, adapted for cobbing ore of the size of stove- or chestnut-coal. The two designs are identical in principle, and vary from each other in minor details only. The apparatus consists of a partially-closed chest, having an opening at f, from the feed-hopper, h, through which the ore is delivered to the machine from an ore-pocket or storage-bin provided with means for regulating the flow of ore, so that, when the machine

Jan 1, 1891

By J. P. Norris, W. T. Pettijohn

The Mufulira Copper Mine, Ltd., is in Northern Rhodesia, ten miles from the Belgian Congo border, and is one of the group of four operating mines comprising the Northern Rhodesian Copperbelt. The ore deposits at Mufulira are on the limb of a large syncline striking NW.-SE. and dipping NE. at about 45 deg towards the Congo border. The host rocks are well-consolidated, highly-silicified, felspathic quarzites of the lower part of the pre-Cambrian Séries des Mines of the Katanga. The ore rocks are underlain, unconformably, by the older "Muva Series," in this case hard, green, metamorphosed quarzites. There are three superimposed orebodies, the first, or upper, orebody averaging 40-ft true thickness with a strike length of about 5000 ft, the second, or middle, orebody of about 50-ft true thickness with a strike length of about 6000 ft, and the third or lower orebody of around 60-ft true thickness with a strike length of 8000 ft. The orebodies are separated by varying widths of waste, or very low-grade ore, from a few feet up to 50 ft. The middle and lower orebodies are so close together for a strike length of 3000 ft that they are mined as one orebody. In all, the mineralized zone is about 200 ft in true thickness.

Jan 6, 1950

By G. Bjorling

The opening oxidation of a hydrometallurgical treatment of natural sulphides must for several reasons be so controlled that a maximum of the sulphide sulphur is transformed into elemental. If the oxidation is performed at low pressure and moderate temperatures and with mild reagents such as diluted nitric acid (or ferric or cupric chloride) the just mentioned condition is realized and it has been found possible to conduct the reaction so that solutions are obtained from which the metals can be recovered and the reagents required for the dissolution are regenerated. Experiments in laboratory scale with nitric-acid promoted oxidation have shown that this method is applicable to several types of raw materials, and in combination with electrodialysis both for partial neutralization and for final regeneration of the circulating acid can the requirements of low consumption of chemical reagents and formation of harmless residues be well fulfilled. The metals can be recovered as cathodic deposits or as hydroxides, and the method should be applicable also for low grade ores and concentrates. Although oxidation of sulphides by ferric or cupric ions has the advantage that it can be performed in open vessels it seems well worth the complication of working with nitric acid promotion in a low-pressure autoclave. Also complex sulphidic, oxidic and metallic materials can be treated.

Jan 1, 1973

By E. R. Shorey

FLOTATION-Mill operator's have recognized that slimes are detri-mental to the flotation concentration of zinc ores. The, presence of primary slime in many of the Wisconsin ores is largely responsible for the failures experienced in treating these ores by flotation. These failures have discouraged the adoption-of the flotation process by opera-tors in the Wisconsin zinc district. The removal of slimes by decantation seemed to be the obvious way to meet the problem of treating slimy or' clayey ores by flotation. To facilitate the removal of slime, it was decided to mix the ore pulp with sodium silicate, which acts to deflocculate the pulp.1 Deflocculation causes slime suspension, making it possible to separate the slime from the sands by decantation.2 Since the literature contains little definite information on the use of sodium silicate to deflocculate ore pulps, a series of tests was conducted to obtain the necessary information. Tests to determine the settling rates of sand and slime in deflocculated pulps were conducted on a dolomite-marcasite-sphalerite ore ground to minus 80 mesh (175 microns) and mixed with water to form a pulp. The deflocculator3 was Mallinckrodt 40° to 42.5° Bé. liquid sodium silicate (Na20 + 3.25Si02). .By microscopic analysis the suspended slimes4 were found to be minus 15 microns (approximately 1000 mesh).

Jan 1, 1934

GOVERNMENT ESTABLISHES DIVISION OF ENGINEERING Government supervision of employment for technical men has been inaugurated by the United States Employment Service, through the establishment of a Division of Engineering, with A. H. Krom, of Chicago, formerly Secretary of the American Association of Engineers, as Director. War demands on the engineering profession have already caused a serious shortage of men with mechanical designing experience and those with practical experience in chemical engineering. At present the professional organizing mediums reach less than 20 per cent. of the estimated 300,000 technical men in the country. This is not a satisfactory arrangement for war times. All the technical men of the country must be reached and, in addition, all men with technical experience must be carefully registered so that they will be immediately available. The advantages of such a governmental registering and systematizing of employment will be apparent at once, to the engineer. Considering that this is principally an engineer's war, the importance of Federal direction of distribution and conservation of the technical service of the country is apparent. The Service will he started through the office of the Director of Engineering, 29 S. LaSalle St., Chicago. All technical men desiring to register for emergency Government work or permanent advancement in positions meeting their qualifications, are urged to volunteer at once for registration, classification and employment.

Jan 8, 1918

By Charles A. Anderson

THE Bagdad copper deposit is of the disseminated type (porphyry copper) occurring in a quartz monzonite stock of late Cretaceous or early Tertiary age. This stock, located essentially at the intersection of two dike swarms, is the only one of several stocks cropping out in the area which is appreciably fractured and mineralized. Most of the rocks in the area are of pre-Cambrian age, but their structures have had no discernible influence on the copper mineralization. Hypogene alteration of the quartz monzonite includes the addition of quartz, orthoclase, and sericite and recrystallization of biotite. The hypogene sulphides are pyrite, chalcopyrite, and molybdenite, the latter younger than the chalcopyrite. The late Cretaceous or early Tertiary igneous rocks, veins, and faults were controlled by northeast and northwest shear zones, the intersection of which marks the zone of appreciable copper mineralization. The minor mineralized fractures carrying the bulk of the copper have a preferred orientation parallel to the intersecting shears, and it is concluded that they are of tectonic origin rather than the result of shrinkage on cooling, crystallization, or mineralization. Supergene enrichment during late Tertiary or early Pleistocene time formed a chalcocite zone providing the minable copper ore. The enrichment was controlled in large part by northeast and northwest faults, particularly at their intersection or where the faults are closely spaced.

Jan 1, 1947

By Michel Daghert, Michel David

In the exploitation of large porphyry type deposits where a cut-off has to be applied and where "internal waste" exists, planning people ask the geologist for the estimated grade of small blocks. Comparison with actual production figures and blast hole assays shows that any kind of weighted average of neighboring DDH (diamond drill hole) samples provides an excessingly smooth picture of reality, resulting most of the time in overevaluation of tons of ore. Solutions based on examination of Past production data exist14 but it would be necessary to have a solution which can be applied before production starts as the preceeding problem also results in an overestimation of the total reserves, often by as much as 20%, thus changing the mine life accordingly and destroying any "optimum planning" which could have been done. The proposed alternative is to forecast the grade distribution of small blocks in a larger block, sufficiently well documented. Several Possible ways to estimate these distributions are reviewed and emphasis is placed on recently developed methods (source G. Matheron) where the coefficients of the orthogonal polynomial series expansion of the distribution of any size of block are directly estimated by kriging. The efficiency of the technique is tested on a level of the Cyprus Pima open pit where the predicted recovery is compared to actual production figures.

Jan 1, 1980

By H. M. Crankshaw

THE early methods of mining anthracite in the steep pitching Mammoth bed consisted in driving breasts up the pitch from the gangways and airways driven in the bed along the strike (Plate 2, Fig. 1). Breasts are simply rooms driven up the pitch the full thickness of the bed (Plate 2, Fig. 2), having a width of from 18 to 30 ft., and a manway or traveling way on one or both sides. (For detail of breast method see Whildin, Trans., vol. 50, p. 704). Many difficulties were encountered, and the maintenance cost of the timbered gangways was so great as to be practically prohibitive. To reduce this .expense, the gangways were driven in the thin Skidmore bed underlying the Mammoth, and the coal mined through rock holes. (Plate 2, Fig. 2;-A.) It was found that after the breasts were driven up 80 to 100 ft., the coal almost invariably rushed or "ran away," making good ventilation almost impossible and the extraction of coal from the upper portion of the lift very difficult. The economic length of a lift is from 200 to 250 ft., and the percentage of extraction by the old method above mentioned was often under 50 per cent., while the coal recovered was so badly broken up as to reduce materially the percentage of large sizes.

Jan 7, 1916

By Samuel D. Warriner

The dealings between concentrated capital invested in the conduct of our various industries and the combinations of labor known as "trade union organizations," have produced not only in the United States, but abroad, many novel methods of negotiation between employers and wage-workers. The size and strength of these organizations have destroyed the personal elements formerly governing the dealings between employer and employee, and have produced various forms of trade-agreements now in more or less successful operation. The difficulty, however, has been to secure consent of both parties to an equitable agreement. For this purpose there have been devised various forms of arbitration, either compulsory under the shadow of governmental legislation, or voluntary by mutual agreement. But these have not been altogether successful from a technical stand-point, for the reason that a compromise has generally been necessary, and in an effort to reach an agreement, terms have been made which have been neither fair nor satisfactory to either of the contending parties. The Anthracite Board of Conciliation represents one of the few thoroughly successful courts for the settlement of trade-disputes, if not the only one which has yet been evolved. The prestige of this board rests upon its successful treatment of the labor-troubles of the anthracite region for a period of more than eight years, and upon the fact that it has been able

Jan 1, 1912

By K. Matsuda, H. Tanaka, M. Mamiya, H. Majima

Copper cementation was studied from both thermodynamic and kinetic aspects. The temperature effect of copper cementation, which has been recognized as an anomalous result, and the rate enhancement phenomenon observed after the initial linear step are, in particular, focused in this work. The main results obtained are as follows; 1) Free energy changes of copper cementation reactions, calculated by the use of the "Correspondence Principle" of Criss and Cobble are rather insensitive to temperature. 2) A Flow-cell assembly consisting of a special cupric ion electrode, a calomel electrode and a potentiometer is particularly useful for the continuous measurements of copper cementation rate. 3) Two first-order reaction rate constants for the CU2+- Fe system were successfully determined by the use of the flow-cell assembly. 4) Activation energies determined for the initial rate and the 9 maximum rate of CU2+ - Fe system are both 4.6 kcal/mole. This fact suggests that the mechanisms of the initial reaction and the final reaction are essentially the same and both reactions are rate controlled by the diffusion in a boundary layer. The difference in the rate constants of them may fie explained by the effect of the nature of surface deposits. 5) Qualitative explanation of the rate enhancement phenomenon from the initial rate was successfully made by applying Bockris "Penetration Model."

Jan 1, 1976

By Henry B. Fernald

THE Federal income tax treatment of expenditures for exploration and development for mines and other natural deposits (other than oil and gas) was materially changed by special provisions of the 1951 Act that are continued in the present 1954 Code." These present provisions for mines in stance they are the same as the 1951 amendments to the 1939 Code, Secs. 23 (cc) and (ff), respectively, except that for exploration the allowable annual deduction is increased to $100,000 (from $75,000) and minor changes in case of property transfers are made with respect to the four-year limitation. Before 1951 the statutes made no specific pro- visions regarding development and exploration for mines, but the rules were prescribed by Treasury regulations: 1) Before the mine entered the production stage, all development and exploration expenditures for mines, less net receipts, were to be capitalized recoverable through depletion or written off as losses when determined worthless. 2) After a mine entered the production stage, development expenditures were deductible as expenses-currently if ordinary expenses, but on a deferred basis if extraordinary in scope. This recognized the two separate periods, one before and the other after beginning of the production stage. There was no distinction between an exploration and a development period, but exploration was included as part of development.

Jan 1, 1958

By A. C. Fieldner

ASH in coal has always been regarded as an undesirable substance, as the heat content of a coal decreases in direct proportion to its ash content. It represents so much inert material that has to be transported, handled when the coal is burned, and finally disposed of. W. R. Roberts, in an address before the Engineers' Society of Western Pennsylvania, Pittsburgh, on Sept. 29, 1925, said that on an annual output of five hundred million tons of coal, a reduction of 3 per cent. of ash means fifteen million tons of refuse and a decrease of $30,000,000 in freight charges. Ash also often prevents efficient utilization of the coal through the formation of clinker caused by the melting of the ash constituents when subjected to heat. The mineral constituents of coal may be of such nature as to make the coal unsuited for specific uses, as for instance, high-sulfur coal for making metallurgical coke. While the usual proximate analysis of coal gives the amount of ash, it gives no information as to the nature and composition of the ash nor of the mineral constituents from which the ash is produced. For the efficient washing of coal to remove ash-forming constituents it is desirable to know the composition and distribution of the ash-forming constituents. Obviously such information is also desirable for the most efficient utilization of coal.

Jan 1, 1926

By Holbrook Botset

EXPERIMENTS performed in this laboratory on the flow of gas-liquid mixtures through unconsolidated sands have been described and discussed in an earlier paper.4 In these earlier experiments a definite relationship was found between the liquid saturation of a sand and its permeability to the liquid or gas phase. Furthermore, the nature of the sand, the permeabilities of the sands over a range between 17 and 260 darcies, appeared to have a negligible effect upon the saturation-permeability relation. Likewise experiments indicated that the viscosity of the liquid, or the substitution of an immiscible liquid for the gas phase, had only a very slight effect on the permeability-saturation relation. This con-clusion has since been definitely confirmed by the experiments of M. C. Leverett3 on the flow of oil and water through unconsolidated sands. The sands used by Leverett were of very low permeability (between 6.8 and 1.04 darcies), while the oil-water viscosity ratio varied between 90 and 0.057. Since the sands that constitute petroleum reservoirs are largely con-solidated, although of widely varying degrees of consolidation, it was desirable to extend the experiments on gas-liquid mixtures to consolidated sand. In the study of consolidated sands additional variables are involved, but for the initial experiments the only new variable to be intro-duced was the cementing material.

Jan 1, 1939

By F. L. Ransome

THAT geology and mining should stand in close and mutually helpful relationship was recognized in the United States at an early period, but it is not possible to set a precise date at which the study of ore deposits became a thoroughly reputable and important branch of geological science. As early as 1850, appeared the first ,part of Foster and Whitney's report1 on the Lake Superior region, devoted mainly to the copper-bearing areas, followed, in the succeeding year, by the second part,2 on the iron lands. This appears to have been the first comprehensive report on what might, at that time at least, be called "western" ore deposits to be prepared and published under the auspices of the Federal government. An outgrowth from this work was Whitney's Metallic Wealth of the United States,3 which appeared in 1854. It was the earliest general work on the ore deposits of the country, and remained a standard reference book for marly forty years. From 1853 on, various parties were sent out by the War Department to explore routes for proposed railways and wagon roads from the Mississippi Valley to the Pacific Coast. Geologists were attached to most of these parties, but their work was mainly of broad reconnaissance character, little attention being paid to ore deposits. Although the

Jan 1, 1933

By R. S. Archer

THE name molybdena was employed by Pliny to denote various substances resembling lead. Later this name was applied to galena-the naturally occurring sulfide of lead-or substances of similar appearance. By the middle of the eighteenth century, it was applied to graphite and to the mineral sulfide of molybdenum (MoS2) now called molybdenite. This confusion is quite understand- able inasmuch as these substances look and feel very much alike. In 1778, the Swedish chemist Scheele published a treatise in which he pointed out essential differences between graphite and molybdenite. On treatment with nitric acid, molybdenite, unlike graphite, produced a peculiar white earth with acidic properties which he called molybdic acid. Since the same mineral gave off sulfurous fumes on heating, he concluded that it was a sulfide of molybdenum. In 1790, there appeared an account of the isolation by P. J. Hjelm of the new element molybdenum, as a metallic powder, by heating the oxide with carbon. It was not until Bertelius conducted the necessary experiments, about 1818 to 1825, that the foundation of the chemistry of molybdenum was laid. The only recorded use of molybdenum during the first century after its isolation was as a chemical reagent, primarily for the determination of phosphorus. It was not until the last decade of the nineteenth century that the use of molybdenum in steel appears to have been investigated. A

Jan 1, 1953

By John W. Trammell, Chester O. Ensign

Efficient mining of copper ore at the White Pine mine in Michigan's Upper Peninsula is partially dependent on the rather unique problem of predicting variations and rock types in a barren stratum called the upper sandstone. The pronounced effect which this formation has on the local mining techniques is reflected by the necessity of deciding whether to mine the sandstone along with ore-bearing rock, thus diluting overall ore grade, or, alternatively, leaving the sandstone behind to form the mine roof. THE OREBODY AND MINING TYPES In the mine, the cupriferous zone of the Nonesuch shale is divided into three major portions (Fig. I). Lying conformably on top of the Copper Harbor formation (or "lower sandstone") is the lower part of the orebody, the parting shale. The parting shale is overlain by the upper sandstone. On top of the upper sandstone, the basal portion (8 ft) of the upper shale is quite similar to the parting shale. Both the upper shale and parting shale are divided into a number of smaller stratigraphic units, each having a characteristic copper content, as shown by the histogram of Fig. 1. Other authors have dealt in detail with the stratigraphy and mineralogy of the orebody, so it will suffice here to call attention to the low copper content of the upper sandstone.

Jan 12, 1964

By Alden B. Grenninger

The time-honored description of the growth of metal crystals to form polycrystalline aggregates is one in which two important steps are considered: (1) nucleation, and (2) dendritic growth, each dendrite starting from its individual nucleus and resulting (upon slow cooling, assuming no solid phase changes) in a macrograin. This picture of the process of crystallization is incomplete, and it is with the hope of enlarging upon it that the following summary and correlation of experimental results are given. Mosaic Structure For an exact definition of the mosaic structure of metal crystals—if, indeed, one can be found that will hold for all metals—one must await the results of much experimental work in this field. The writer's investigations have been confined almost entirely to copper and a few of its alloys. The following terms are proposed, and will be used in this report: Macromosaic Structure1.—Large-scale mosaic structure; more specifically, mosaic structure of a scale large enough to produce splitting of Laue spots on back-reflection Laue X-ray patterns2. The deviation from exact parallelism of neighboring macromosaics varies from a few minutes to a few degrees3. Just as there are no exact dimension limits for macrograins, so the dimensions of a macromosaic vary considerably. Macromosaic structure may often be seen on copper single crystals if they are examined carefully with critical illumination4. However, back-

Jan 1, 1936

By Ole Singstad

THE legislatures of New York and New Jersey, determined in 1919 that a vehicular tunnel should be built under the Hudson River. On July 1, 1919, an engineering staff was organized with the late Clifford M. Holland as chief engineer, and this staff was given a number of problems to solve, such as location, size, type of tunnel, method of construction, method of ventilation and cost. After a period of preliminary investigations and studies it was decided to build the tunnel at Canal St., New York, connecting 12th St., Jersey City. This is the center of the heaviest traffic across the Hudson River. It was also decided to build two tunnels-one for west-bound traffic and one for east-bound traffic-the tunnels to be of cast iron, built up of segments and bolted together, each tunnel to have a roadway 20 ft. wide and a clear heat room of 13 ft., 6 in. This is to provide for two lines of vehicles in each direction. The tunnels have an exterior diameter of 29 ft., 6 in. The interior lining is of concrete, the sidewalls tiled with a vitreous white tile and the roadways paved with granite block. The entrances and exits at both ends are separated by two blocks so as to reduce traffic congestion.

Jan 8, 1926

By Caner Zanbak, Erdogan Yüzer, Mahir Vardar, Kemal A. Erguvanli

The Hasancelebi iron deposit in Eastern Turkey is a very low grade (average 20% oxide) magnetite body consisting of 720 million longtons of proven reserve at a 10% cut-off limit. The ore-bearing scapolitic oclcs cover an area of approximately 4300m x 300m, and the thickness of the outcropping deposit exceeds 300m. Prefeasibility project studies revealed that a one degree decrease in a 45° final slope angle of the proposed pit would require excavation of approximately 10 million cubic meters of excess waste material, for a projected pit bottom 300 meters below the valley floor. There- fore, determination of the final slope angles of the open pit was considered to be the most important task in the feasibility analysis of this project. In this investigation, the main emphasis was given to collection, compilation and evaluation of the engineering geological, hydrogeological and rock mechanics data of the highly fractured and weathered rocks. Due to the presence of intense fracturing, the rock wedge analysis method was used for projected 30m-high benches and the circular failure analysis method was used for the stability of the projected final pit slopes. The proposed bench slope angles ranged between 60° and 80°, whereas the projected final slope angles varied between 30° and 48°, depending on the slope heights and groundwater levels.

Jan 1, 1983