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By K. Osseo-Asare

The DIAGRAM computer program has been used to develop stability diagrams such as Eh-pH, log [CNI-pH, and log [Me]-pH for the systems Me-CN-H 0 where Me = Au, Ag, Fe, Zn, Cu, Ni, Co. More complex 2 diagrams involving sulfur- and arsenic-containing species are also presented. With the aid of these diagrams, a discussion is presented of the solution conditions (e.g. pH, [CN], [CNS], Eh) vhich influence gold and silver extraction in cyanide solutions. Special emphasis is given to the effects of ore minerals or calcination products, such as pyrrhotite, pyrite, arsenopyrite and hematite on gold-silver dissolution. Application of the stability diagrams to solution treatment operations such as cementation is also indicated.

Jan 1, 1984

By J. Leland Myer

IN a precise study of Pennsylvania anthracites, the research on European. anthracites is of little value to us because of their different physical and chemical nature. Likewise, there can be little correlation with the physical properties of bituminous and lower rank coals. Although all high-rank coals are thought to have had a common origin, microscopic examination revealing essentially the same kinds of organisms in similar .states of preservation, the different physical properties apparently arise from the degree or kinds of metamorphism of these coals. Representative samples from the Pennsylvania deposits have been selected for analysis, together with graphitic anthracite, bituminous coal, and some of the common forms of carbon. A complete list, with descriptions, is shown in Table 1.

Jan 1, 1932

Jan. 7, 1952, AIME, Boston Section, Massachusetts Institute of Technology, Campus Room, Graduate House, Cambridge, Mass. Jan. 8, Society for Applied Spectroscopy, 6 pm, supper, Tosca's; 8 pm, meeting, Socony-Vacuum Training Center, 63 Park Row, New York. Jan. 9, AIME, Chicago Section, Chicago Bar Assn., 29 S. La Salle St., Chicago. Jan. 13-15, Institute of Scrap Iron & Steel, Waldorf-Astoria, New York. Jan. 14-1.6, AIME, Minnesota Section, Hotel Duluth, Minn. Jan. 14-18, SAE, annual meeting, Hotel Book-Cadillac, Detroit. Jan. 1.6-18, Society of Plastic Engineers, Inc., annual national technical conference, Edgewater Beach Hotel, Chicago. Jan. 17, AIME, New York Section, Mining Club, 33 Broadway, New York. Jan. 1.7, AIME, Utah Section, Newhouse Hotel, Salt Lake City.

Jan 1, 1952

By J. Weng

The equations of heat conduction are numerically solved for two kinds of artificial freezing- mechanical freezing and liquid nitrogen freezing. A two dimensional finite difference model simulating the freezing field is developed. The procedure introduces a way to simulate the effect of latent heat released when water transforms from liquid to solid. The procedure also produces a way to calculate the harmonic mean of heat conductivity used when dealing with heterogeneous material. The theoretically derived temperature distributions in frozen soil are given and compared with measured data. An analysis made on the thermal design in shaft freezing. The average temperature of frozen soil is calculated by using numerical integration. The regularity of development of frozen soil radius is revealed and given in an appropriate mathematical model.

Jan 1, 1984

By K. E. Niermeyer, J. A. Bratt, B. A. Fahm, B. A. Kennedy

The instrumentation, monitoring, and prediction of a major slope failure at the Chuquicamata mine are described. In December 1967, preexisting tension cracks on the south end of the east wall of the mine began to open. Various forms of instru¬mentation were installed for continuous monitoring. These systems included tension crack stakes, crack extensometers, linear extensometers, tape and transit lines, sliding wire contacts, and a seismograph. From the information obtained, the failure date was accurately predicted some five weeks before failure, enabling the mine to reroute truck and rail access; hence, causing a minimal mine shutdown of 21/2 days and preventing any injuries to person or damage to equipment. The shape and form of the sliding mass are analyzed, as are possible modes of failure.

Jan 1, 1972

By Rixford A. Beals

Dry grinding without balls is feature of this mill now in use in three countries on two continents. Materials being ground commercially include iron ore, gold ore, asbestos rock, and slag. New large beneficiation plants have been using an almost standardized crushing and grinding flowsheet. Typically a primary gyratory is followed by several stages of fine crushing and grinding is often carried out in a rod mill operating ahead of one or more ball mills. The clearly labeled trend is to an increasing number of stages with a decreased reduction ratio per machine. Current Aerofall mill installations represent a complete reversal of this trend-one mill replaces the several stages of crushing and grinding a more conventional flowsheet would call for.

Sep 1, 1955

By D. A. Dahlstrom

(A. C. Richardson and Charles C. Boley, presiding) W. E. BROWN*—In the operation of the cyclone, what factors have you found that will affect its results as far as efficiency goes; for example, if you have coming through the cyclone a pulp of 20 gpm, that has, say, 25 or 30 pct solids, and then from operational characteristics this pulp changes to 35 pct solids but it is still maintaining the same ratio of flow. HOW does that affect the cyclone;) D. A. DAHLSTHOM (author's reply) —It has a definite effect, as you know from Mr. Sutherland's paper,l3 in that as you increase the solid concerltration of your inlet slurry, you will naturally have an according effect on the overflow concell-

Jan 1, 1950

By J. C. F. Randolph

This mill being now in successful work, it seems proper to record some professional memoranda concerning it. It is intended to handle an unusual ore, in a locality difficult of access, and its arrangement and method of procedure present some novel features of interest. It was prepared for the San Miguel property at Batopilas, State of Chihuahua, Mexico, owned by the Consolidated Batopilas Silver Mining Company of New York, at present under the management of ex-Governor Alexander R. Shepherd. This property contains a large series of more or less parallel veins, worked through a deep cross-cut tunnel 1300 feet in length. The vein rock of these veins is calcapar in diorite. While, near the stirface, ruby silver, black

Jan 1, 1882

By Fred W. Menzl, Raymond E. Sutton

GABBS, Nev., in Nye County, is 140 miles southeast of Reno and about 31 miles north of the Southern Pacific railroad at Luning. The townsite lies at the eastern edge of Gabbs Valley, and plant and quarry operations are in the foothills of the Paradise Range at elevations from 5000 to 5900 ft. Hard-surfaced roads connect with main U. S. high- ways on the north and south. Historical Background: Brucite, a magnesium hydroxide mineral, was discovered in the Gabbs area in 1927 and magnesite, the magnesium carbonate, was found later on claims originally staked and worked for the tungsten mineral scheelite. The brucite is on a granodiorite contact and the magnesite is usually some distance away from the granodiorite

Jan 7, 1957

By R. B. Sudderth

The recovery of copper by various combinations of processes centered around liquid ion exchange has certainly been accepted as a technically superior entity when compared to the widely applied classical method of cementation. While the technical aspect of liquid ion exchange processes has received much attention and acclaim through actual operating data, in particular the ease of handling solutions, percentage recovery, reduction of pollution, etc., the corresponding economic data has either gone unpublished or has been held confidential. Much of this economic data has now been made available for publication; and with this data, we at General Mills Chemicals, Inc., will attempt to present an accurate economic analysis of some liquid ion exchange plants and an economic comparison between these plants and the typical cementation facility.

Jan 1, 1974

By Gordon C. Rausser, Michael D. Boehlje, Richard A. Levins, John A. Otte

Changes in SO2 emission standards will not only influence the cost of supplying energy demands from coal, but also the competitive position of various production regions and the method of mining (surface vs. underground). A multiperiod interregional competition model was utilized to evaluate the interactions between mining capacity, new mine development, coal reserves, mining, processing and transportation costs and equipment availability and SO2 emission standards. The empirical results indicate that not only will costs increase dramatically, but production in eastern as well as western regions that have low sulfur reserves will also increase as sulfur standards become increasingly more strict. Implications of the adjustments in the location of coal mining activity for the processing, transportation, and capital goods markets are also presented.

Jan 1, 1978

By Howard M. Wells

The investment worth of a mineral deposit can only be realistically evaluated in relation to specified engineering design criteria which fully detail the proposed method of exploitation. The operational design of a mine falls essentially within the technical discipline of the mining engineer, under the constraint that the technical design should be aimed at optimizing the financial attractiveness of the project. In the case of a marginally viable proposition it becomes vitally necessary to identify the best set of design parameters which together will add up to an optimum investment proposal. This paper examines some fundamental logic of optimization for a "wasting asset" type of investment such as a mine, with special reference to the rate of annual production and the strategy of selective mining.

Jan 12, 1978

By John C. F. Randolph

THIS mill being now in successful work, it seems proper to record some professional memoranda concerning it. It is intended to handle an unusual ore, in a locality difficult of access, and its arrangement and method of procedure present some novel features of interest. It was prepared for the San Miguel property at Batopilas, State of Chihuahua, Mexico, owned by the Consolidated Batopilas Silver Mining Company of New York, at present under the management of ex-Governor Alexander R. Shepherd. This property contains a large series of more or less parallel veins, worked through a deep cross-cut tunnel 1300 feet in length. The vein rock of these veins is calespar in diorite. While, near the surface, ruby silver, black

Jan 1, 1882

By William P. Blake

(Read at the Amenia Meeting, October, 1877.) EUREKA has for several years past been known as one of the most important centres of production of argentiferous lead in the country. The average daily yield is now one hundred tons of lead bars, in which the silver and gold of the ore is concentrated. The value of this lead, called "bullion," is about $300 per ton. To produce this quantity of metal, about four times the weight of ore, or say four hundred tons, is required. Most of this ore is supplied by the two leading mines of the district, the "Eureka" and the "Richmond," adjoining claims on Ruby Hill, about two miles from Eureka. There are, however, many other mines from which considerable quan-

Jan 1, 1878

By Kenneth Robertson

THEREi9 probably less known of this subject than of any other connected with the metallurgy of iron. In all the books that treat of this mattes, there are given analyses of slags, their chemical formulae, the loss of iron, etc. ; but few, if any, give the character of the iron made at the time ; none give analyses and physical characteristics of the ores and limestones used, and they present merely isolated examples from various furnaces, and consequently one is more frequently puzzled than enlightened after reading them. During two years I have had occasion to analyze the slags and many of the pig-irons from two furnaces, and for this article I have made analyses of all the different grades of pig made by them. A

By R. Kirk

The problems of getting air to the working face of a mine (or perhaps the problems caused by not getting air to the working face) have led to the development of an analogue system in England that reputedly bypasses many of the drawbacks that such systems have encountered in the past. The unit was developed for the Wolstanton Combined mine, an underground operation consisting essentially of three collieries situated in the center of the North Staffordshire coalfield. This combination of workings, which employs a total of eight shafts, brings with it complex ventilation problems, and in order to study these problems and to assist in the control of the established ventilation system, a Ventilation Analogue has been designed and installed to permanently represent the mine's ventilation system.

Jan 4, 1964

By M. Tsunekawa, T. Takamori, T. Hirajima

In spherical agglomeration in water, the pattern of the growth behaviour of agglomerates is essentially determined by the surface chemical properties of the particles and the oil-water interface. When particles are suitably hydrophobic and oil-water interfacial tension is not too low under an adequate condition for agglomeration, large agglomerates are formed in the initial stage and micro- agglomerates do not appear. When particles are poorly wetted by oil and the interfacial tension is low, initially micro-agglomerates are formed and, after certain aging time, they grow to large agglomerates in a relatively short time without formation of intermediate size agglomerates. Under adequate conditions, the amount of oil and power input do not produce any remarkable effect on the pattern of growth.

Jan 1, 1980

By Clintford R. Jones, Om P. Pande

This chapter presents a survey of instrumentation and control systems used on ball mill circuits from the past to the present. It is based on the concept of optimization of plant practice, and addresses the influence of the circuit design on the control strategy and on the instrumentation philosophy. Methods of optimization of the grinding circuit, within the constraints of the mill design requirements, are reviewed. The modern use of automation and circuit optimization is critically reviewed for known and possible conceptual control loops. A comparative study of circuit variations due to instrument hardware, location and installation is provided. Future trends i.e., computer control (DDC) and the effects on both the control stratagems and the optimization stratagems are described.

Jan 1, 1982

By R. J. Keene

The South Works high-tonnage billet caster was started in late March 1971, with the first heat being successfully cast to completion. Currently, over 31,500 tons per month are being produced. U. S. Steel designed and built this caster with the objective of producing quality-steel billets for critical bar, rod, and wire applications. The essential design parameters were based on studies conducted on the Research Laboratory's pilot caster, also located at South works. 1,2,3)* The caster is a four-strand, straight-mold machine that produces 7.5-inch- square billets at rates exceeding 300 tons per hour. An in-line-reduction mill reduces each strand to either 6-inch-, 5-inch-, or 4-inch-square billets.

Jan 1, 1972

By A. M. Gaudin, D. W. Fuerstenau

IN concentration of certain ores by soap flotation, prevention of quartz flotation is desired; the contrary is true in treatment of some oxide iron ores. Experimental study of the flotation of quartz goes back at least a quarter of a century.' Clean quartz does not float with fatty acids or soaps but does float when activated by one of many metallic salts. Control of pH is important. Broadly speaking the problem of quartz flotation has been approached from the empirical side, as was the related topic of flocculation or dispersion of quartz suspensions.' Empirical studies indicated the existence of critical relationships between the additions of collector and activator. These additions were not stoichiometric for the formation of soaps of the activator cation.

Jan 1, 1955