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By D. S. Newton

Introduction Historically the production of zinc dust has been based upon residual and secondary zinc. Using horizontal retorts filled with diecasting scrap, galvanizers drosses and sweater billets, dust has been produced by condensation into static condensers on a 24 hour cycle. Although fairly flexible as regards input materials the process is not amenable to close control of the product, is labour intensive and unless carefully run can cause fume problems. With a steadily increasing demand for zinc dust of consistent properties and higher quality there is a demand for an improved method of manufacture in which dust can be produced continuously and which is capable of close control thus ensuring a minimum amount of oversize or unsaleable material. The Process in use in the works of Imperial Smelting Corporation (Alloys) Ltd. in England, and in Canada and Holland, satisfies the criteria stated above, and has proved to be easy to control with a minimum labour demand.

Jan 1, 1970

By Charles E. Johnston

The haulage system at the International Minerals T & Chemical Corp. (IMC) potash mine near Carlsbad, N. M., reached a turning point in December 1956 with the introduction of rope suspended belt haulage. In fact, IMC pioneered the use of this type of belt in the potash industry. Since that time belt conveyance has been employed as an extension of the rail system but not as a replacement of the main rail haulage. IMC's potash mine is located in the Permian Basin, approximately 20 miles east of Carlsbad. From three levels, the 800-ft, 850-ft and 900-ft, over 60 million tons have been extracted. Langbeinite (K,SO,. 2MgS0,) is mined on the 850 level and sylvite (KCl) on the 900 level. The 800 level, with both langbeinite and sylvite mineralization, is idle. Mining heights vary from 54 in. to more than 10 ft. A room and pillar mining system is used.

Jan 3, 1963

By Thomas D. Henderson, Donald E. Crowell

INTRODUCTION This paper presents a "case history" of the steps taken to estimate capital and operating costs for a typical porphyry copper concentrator of ±9,070 metric tons (10,000 short tons) per day capacity. The concentrator described herein is hypothetical, but is based on experience and is, in effect, a composite of several actual projects. The numbers used are illustrative only and do not represent actual costs at any particular concentrator. These numbers are, however, representative of typical milling costs at one point in time, and. are sufficiently accurate to illustrate the cost estimating procedures described in this paper. It is not possible to publish actual, current milling costs and, in any event, actual cost figures quickly become meaningless in today's economic situation with various costs all rising at different rates. The paper is divided into three parts: (1) order-of-magnitude estimate, (2) feasibility study estimate, and (3) discussion of differences between estimated and actual costs.

Jan 1, 1978

By Richmond Bennett

Airborne geochemistry became a reality with the advent of a high-sensitivity air¬borne gamma ray spectrometer with large volume NAI(Tl) crystal detectors. The high-sensitivity spectrometer measures small variations in the concentration of potassium (as Ks°), thorium (as Tl308) and uranium (as Bi.214) along the flight lines in the area surveyed. Hydrothermal dispersion patterns are indicated by anomalous measured values of the concentrations of potassium, thorium, uranium, or their ratios. In two recent Australian survey areas, copper mineralization was located along favorable structures within hydrothermal dispersion patterns delineated by airborne geochemical surveys. In metamorphic terrane where there had been po¬tassium metasomatism, the hydrothermal dispersion patterns were indicated by high potassium/uranium ratios (K40/Bi). In a sedimentary environment that had been intruded by a stock, the path of hydrothermal fluids was indicated by uranium (Bi214), thorium (TV'), and uranium/ thorium (Bi214/Tl208) ratios.

Jan 1, 1972

By H. N. Herrick

THE flow characteristics of drilling muds, as described in this paper, and the method given for solving problems relating to the flow of these muds through pipe and accessory equipment, are based on a conception that drilling muds are plastic solids like paints or greases; not liquids. The data presented in this report have been obtained from studies of California muds, chiefly those used in the Kettleman Hills field, by the Producing Department of the Standard Oil Company of California. Although no claim of scientific exactness is made for the formulas and diagrams, since the data upon which they are based, are not. complete even for California muds, the method has proved to be a convenient means for estimating, closely enough for practical purposes, the pressures required to force muds at various rates through pipe systems in which they are handled. Certain approximations have been made to simplify the procedures so that they can be used easily in the field.

Jan 1, 1932

By A. J. Nicol

Field experience in uranium has shown it is most economical to ram through a drilling program to obtain maximum footage per drill hour. Drift surveys can then determine the course of the holes. Using this method is generally cheaper than paying the additional cost involved in using the drilling technique and equipment necessary to maintain straight holes. Factors Affecting Direction of Bit Travel: In all rotary-drilled holes there is an interplay of forces or conditions affecting the direction of bit travel. Rarely is a straight vertical hole obtained. One of the major factors is weight on a drill string. In looking at a joint of drill stem it is hard to imagine its being quite flexible, but flexing of the steel increases when many joints are made up together, and even a slight weight added to the upper portion causes a buckling or spiraling effect in the hole. The result is that the bit deviates from the vertical.

Jan 1, 1959

By R. V. Ramani, Ish K. Chopra, Robert Stefanko

The results of a recent study on the influence of continuous and conventional mining techniques on the size consist and washability characteristics of coal are presented. Eight samples, four each from continuous and conventional mining sections, were collected. Each sample was screened in seven size fractions, and each size fraction was totally fractionated at five gravities. The data thus collected were statistically examined for the influence significance of mining techniques, size, and gravity on the quality of the mined product. The paper presents the sample collection method, data gathering and analysis procedures, and major conclusions. The study revealed that there are pronounced differences in the products from the two mining systems and that conventional mining yielded a better product in terms of size consist, yield, ash, and sulfur in both the raw and washed products. The results of the study are significant in regard to consideration of resource utilization and conservation, and environmental impacts.

Jan 1, 1976

By Donald Ingvoldstad, Harold E. Lee

At Bunker Hill the original charge storage and preparation system was installed in 1917 to accommodate lead-silver gravity mill products. Only minor tonnages of wet fines such as vanner and flotation concentrates were received. Charge flux and diluent requirements were provided by an ample supply of siderite middlings and coarse limerock. While oversize material was crushed through Y4-in., the use of roll crushers in series resulted in a more or less granular, free-running charge of adequate porosity. Under such conditions, receipts could be proportioned directly from receiving bins, and suitable blending was obtained by passing the resultant layered composite through a small Stedman disintegrator. This elementary system served well for production and smelting of an extremely lead-rich sinter, in the low column blast furnace. Here sinter physical quality is less critical, and appreciable quantities of raw flux and oxidized ore may be charged directly to the blast furnace without seriously impairing furnace capacity.

Oct 1, 1956

By Wilson D. Michell

THE Magma copper vein trends east-west, dips 70° south, and cuts through a 6000-ft thickness of limestones, quartzites, shale, diabase, and schist. The vein is itself a fault with -a horizontal offset of 500 ft on the formation contacts in the two walls. There are two principal faults of large displacement and numerous smaller steep and flat faults that complicate the prediction of ore occurrence. A study of the geology, its systematic recording to facilitate ready reference, and graphic methods of interpretation of mineralization have aided the exploration, development, and mining of the ore. In making predictions of the distribution of mineable ore bodies and their shape in critical areas, studies are made of "mineralization contours" and "mineralization trends," which are developed on a longitudinal section of the vein from variations in the concentration of the combined base metal content as shown by assays of available openings in the mine.

Jan 1, 1947

By Larry G. Hayes

Development of the Bowers-Campbell zinc deposit, located in the Shenandoah Valley two miles northwest of Timberville, Va., was commenced in 1956 by the Tri-State Zinc Co. The occurrence of lead-zinc mineralization in this area has been known for many years, but the first serious exploration program was initiated in 1951 by the geologic staff of Tri-State Zinc Co. Ordovician dolomites. The deposit is approximately 700 ft long, 100 ft wide, and 475 ft thick. Its projected plan has an elongated ovoid shape, where- as the profile appears boot-shaped with the upper portion outcropping. Vertical cross sections show the lense as having been thrust-faulted along certain bedding planes. The movement along these bedding thrusts varies greatly and in one case, has offset the deposit so as to divide it into an upper and lower orebody. The breccia lense strikes parallel to the N 34" E strike of enclosing strata.

Jan 9, 1960

THE Searles Lake orebody is located in the north- west corner of San Bernardino County. It is a dry lake bed with an exposed salt surface covering an area of 12 square miles. Recoverable mineral values are contained in the mother liquor below the surface of the lake. Stratification in the lake bed has separated the brine into two bodies which differ in composition. Although liquor is processed from both bodies, this paper will discuss only the upper structure brine. Fig. 1 illustrates a typical cross-section of the two commercial orebodies. The orebody is composed of a porous salt deposit 70 to 90 ft deep. The upper structure is separated from the lower orebody by a 12 to 16-ft thick impervious mud seam, as shown in Fig. 1. These salt structures are composed of 55 pct solid-phase salts and 45 pct voids which are filled with the original mother liquor.

Jan 2, 1954

By Joseph Moses Botbol

This study was designed to demonstrate the viability of using high-frequency radio transmission as a means of communications between a remote field camp and a time- sharing computer system. A field camp near Johnstown, Pa., was linked by high- frequency radio to a base station 160 miles to the southeast in Vienna, Va. The base station was in turn linked by telephone to a time-sharing computer system near Los Angeles, Cal. Error-free data transmission utilized highly stable receivers and transmitters, forward error correction, and dual-frequency diversity. Three geologic applications programs resident in the Los Angeles computer were executed from a graphics cathode ray tube terminal in the field. Bulk data equivalent in volume to 4 days of typical spectrographic analytical work generated by one spectrograph and one spectrophotometer were transmitted from the field to the base station. All programs, were executed successfully, and all data were transmitted error free.

Jan 1, 1976

By Charles J. Haas

The effectiveness of rock bolts in resisting shear displacement along preexisting fracture surfaces or slip planes was determined in the laboratory with full-scale bolts and large-scale shear test equipment. The system variables were the type of bolt, orientation of bolt relative to shear surface, and normal pressure on the interface. Results showed that, in general, both conventional bolts and resin- grouted reinforcing bars significantly increase the shear resistance along a fracture or bedding plane when the average normal compressive stress on the plane is in the order of 25 psi and when the bolt is oriented such that it tends to lengthen as the shear progresses. An increase in shear resistance is also noted at the higher normal pressure of 250 psi; however, the increase is small compared to the corresponding shear resistance without a bolt. Conventional bolts oriented such that they lose tension as shear displacement occurs added no shear resistance since the tension drops to zero at very small shear displacements.

Jan 1, 1977

By Fred C. Bond

It sometimes happens that old knowledge is forgotten, or half-forgotten, and its rediscovery is hailed as a great new advance in technology. Autogenous grinding affords such an example. The oldest-or apparently the oldest-commercial application of continuous autogenous grinding on a large scale outside of South Africa occurred at San Juancito, Honduras, where a total of more than two million tons of silver ore were ground autogenously with complete success from 1918 to the early 1940's. The history of the San Juancito silver deposits begins in 1880 when- the New York and Honduras Rosario Mining Co. started mining silver at a rate which soon reached two million ounces of silver annually. In 1912 the Company's first mill, located in the village of San Juancito, was shut down and its equipment transferred to a new cyanide plant. This plant, constructed on a mountainside near the mine, was equipped with tube pebble mills in which Normandy or Danish pebbles were used initially.

Jan 5, 1963

By B. S. Butler

Introduction. THE New London copper mine, about 81, miles east of Frederick, Md., was visited by the Writers for a few hours in the spring of 1909 and the following brief notes on ore specimens collected are presented as a contribution to studies in chalcocite ores. For certain data on the structural and areal geology of this portion of Maryland the writers are under obligation to the unpublished notes and maps of Arthur Keith. The detailed study of the ores is the work of B. S. Butler. The deposit here discussed has many similarities to those of the Virginia district of Virginia and North Carolina, which have been described y Graton1 and Laney2, except that in the deposits of the New London mine chalcocite is by far the most important ore mineral, while in the Virginia deposits bornite is commonly-the most important sulphide. In the New London occurrence calcite is the most important gangue mineral.

Jan 7, 1914

A mine that staggers the imagination is Chuquicamata, the granddaddy of them all. In 1968 production exceeded 300,000 tons of copper. Production began in 1915 and mining proceeded solely on oxide ores until 1953 when the first treatment of sulfides began. Today the company has mined about 1.2 billion tons of all types of material since inception. The accelerating rate of output can be gauged by the comparable 1946 figure of production-to-date which was 350 million tons. No single mine comes close to touching Chuqui for productivity at its high annual metal yield mining only 90,000 tpd of ore at the luxurious waste-to-ore ratio of 0.6 to 1. However, the complexity of the operation is enormous and the experience required to synchronize the various processes is masked by normal operations and only becomes apparent in times of emergency such as when the slide took place in the pit in February.

Jan 11, 1969

By John V. Beall

Thai means free. Historically accurate, as the country has never been subjugated by foreign occupation, the name "The Land of the Free" also seems to fit the attitude of the people. At the Bangkok airport, without so much as a kopkhun (thank you), travelers are found behind, beside and in front of ticket counters. A pretty Thai face on TV calls flights in English and Thai. Baggage disappears with alarming rapidity and your reporter and spouse despaired of ever being reunited with it. But at the entrance, all the parts came together and there was even a limousine from our hotel, The Oriental. Driving downtown English style, we noted that there were four lanes of traffic occupying the space we would allow for three lanes. Motorcycles and enclosed three-wheel motorcycle taxis were much in evidence, but the occasional water buffalo held up the slow lane. In the city, men wore European-type slacks and shirts but the women were colorful in traditional ankle-length wraparound skirts.

Jan 1, 1970

By H. D. Kessler, F. A. Crossley, J. J. Rausch

The titanium-rich corner of the system Ti-AI-V has been studied to determine the phase relationships in the temperature interval 600° to 1200°C. Metallographic examination of long time isothermally annealed specimens was the principal method of investigation. TWENTY-SIX alloys in the region 1 to 22 pct A1 and 2 to 11 pct V, and the temperature range 600° to 1200°C, were studied as part of a program on phase relationships and transformation processes of titanium alloy systems. Experimental Procedure Preparation of Alloys—Materials used in the preparation of alloys were high purity Bureau of Mines sponge titanium (103 Bhn), 99.7 pct pure V chips obtained from the Electro Metallurgical Div., union Carbide and Carbon carp., and 99.71 pet pure A1 in the form of granulated shot from Aluminum cO. Of The alloy ingots, weighing l5 g, were melted in a nonconsumable tungsten electrode arc furnace un-

Jan 1, 1957

A LARGE proportion of the steel that is melted and refined in the United States and poured into ingots is made in basic open- hearth furnaces. The capacity of these furnaces varies over a wide range with a large majority falling within limits of 50 to 200 tons (Fig. 1) The two general types of furnace design used are stationary [ ] and tilting furnaces, the former being much more common. The fuel burned in such furnaces is either one of several types of gas, or a liquid fuel such as oil or tar, or a combination of gas and liquid fuel. GENERAL FEATURES OF FURNACE CONSTRUCTION The design of a modern stationary furnace built to burn liquid fuel and with a capacity of 175 tons is shown in Figs. 2 to 4. The cross- section of the furnace at the tap hole is illustrated in Fig. 2, which shows the bottom construction, sloping back wall, and the rigid steel

Jan 1, 1944

By Frederick J. McGarry, Parviz F. Rad

Although tunneling machines have attained very high advance rates in medium-hard rocks, the need for frequent repairs has slowed their use in very hard rocks. Laser- assisted tunneling is expected to improve tunneling machine performance by improving either specific energy or amount and quality of muck. The beneficial effects of lasing are the initiation and growth of microcracks from differential thermal expansion of grains, and overall spalling in the vicinity of the lased area. Using a constant thrust rock cutting device with disk cutters, the effects of cutter geometry, cutter diameter, thrust, and speed variations on specific energy and muck were explored and the improvement in performance of disk cutters caused by lasing was evaluated. It was found that the improvement depends on beam power and density, beam speed, pattern of heating, and cutting pattern and procedure. A focused beam slightly offset from the cutter path gives the most improvement both when cutting on a smooth surface and when cutting in previously cut grooves.

Jan 1, 1971