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By W. R. Bendy

GRINDING is a large and costly part of Portland cement manufacture. Prior to clinkering in the rotary kiln, raw materials are ground to a fineness of 80 to 90 pct passing 200 mesh. Then, after burning and cooling, the resulting clinker is ground to about 92 pct passing 325 mesh. In the cement industry the most favored method of grinding has always been by impact and attrition of a ball charge in a rotating mill. Other types of mills, in which materials are ground between die rings and rollers, or between die rings and large balls, are sometimes used for single-stage grinding and often for preliminary grinding followed by grinding in ball-type mills. Their efficiency is usually high, but maintenance and repair costs are high also, and the ball-type mill continues to be the most widely used.

Jan 10, 1957

By S. C. Suboleski, C. B. Manula

In a high risk venture such as mining where capital is committed and contracts are signed on a minimum of information, decisions are based primarily on production forecasts derived through consideration of such factors as management-labor relations, mining practice, variations in physical conditions, and the equipment applied. Among these factors, the physical conditions offer the least opportunity for control, and, due to the wide range of mining conditions experienced, little effort has been made to develop objective methods for measuring their effects on mine output. This paper's aim is to demonstrate a method for assessing these relationships that can be applied under a wide range of conditions both in new mines and in working sections where there is a need to determine the impact of proposed operational modifications. Using empirical data from active underground mines, a mathematical model was developed to derive a set of regression equations for predicting production as a function of mining conditions.

Jan 1, 1982

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 A. Tremari, Paul I. Eimon

Photogrammetrists are studying with new interest the problems of mine mapping and mining engineers are beginning to see what photogrammetry can do for them. Administrators in a number of European and U. S. mines have tried photogram- metric methods and are finding that better maps and data, needed for mine development, can be produced with savings of time, men, and money. In addition to wide use in small scale mapping projects, photogrammetric methods are now used for producing large scale plans and maps in German coal and lignite mines, in some U. S. open pit mines, to inventory TVA coal stock piles, and to compute highway excavation volumes. In each case surveying and map compilation has been made more efficient and accurate by photogrammetry and at significant savings over ground methods.

Jan 5, 1959

Jan 1, 1925

By Bruce A. Lamberton

In U. S. underground mines concrete work is not widely used. Timber and steel are cheaper, and there are few serious water problems. But in the Union of south Africa men dig deeper, more persistently, and probably more profitably than anywhere else on earth. Some gold mines near Johannesburg are below the 10,000 level and employ as many as 35,000 natives on a single property. Underground substations, pump chambers, and air conditioning plants have capacity to serve small cities. The complexity and extent of underground operations and the heavy subsurface water flows, especially in the new Free State gold fields, require heavy in a Deep concrete installations.

Oct 1, 1956

By Richard Hamburger

Calculating machines permit the use of the more rapid cotangent and semigraphic solutions of plane triangulation. The results of these methods are as accurate as those of other methods. Simple adjustment of the net, and ease of calculation encourage more complete field work. Errors in field work or in computation are easily localized.

Jan 2, 1950

Succession of Minerals and Temperatures of Formation in Ore Deposits of Magmatic Affiliations BY WALDEMAR LINDGREN (Tech Pub 713 10,000 words ) The paper presents data accepted by many geochemists and geologists regarding the succession of minerals and the temperatures of formation in ore deposits affiliated with igneous rocks It also presents the individual views of the author on the composition of the solutions that were active and on the mode of deposition He does not regard these views as speculations or hypotheses but as forming a well motivated and con¬sistent theory It is not certain, however, that all investigators will subscribe to them The mining engineer may not always be interested in the field of stability and tempera¬ture of origin in the mineralogy of ore deposits, but he certainly is interested in the succession of minerals because this has a definite bearing on the understanding of the ores and on the best processes of extraction The author, therefore, summarizes in plain language the principal features of succession as shown in metallic ores

Jan 1, 1937

By John F. Abel

In the debate between miners and ecologists, our industry has at last begun to get some of its story told. I have been told many times that it is hopeless to even try to get our side across. Some are sure that no one will believe us even when our cause is just. My reply would be that we have to tell the truth; again, again, and again. We will never convert a fanatic, but we must try to reach the reasonable and thinking people. I am encouraged because more of us are trying. Various mining companies here in Arizona have bought newspaper space to set forth some of the facts around our local environmental problems. The Arizona Mining Association co-sponsored a symposium in March: Mining and Ecology in the Arid Environment. The symposium program included tours arranged with local mining companies. The participants saw an acid plant, an acid leaching operation, an alluvial tailings dike, a tailings pond, a smelter, and a couple of open pit mines. This wouldn't phase you until you realized that half the visitors were ecologists, watershed and wild- life managers, and other assorted conservationists. It took a lot of guts. I am proud that we had that much confidence. As Pogo said, "We have met the enemy and they is us!" Actually, we met the enemy and they were just like us-concerned.

Jan 1, 1970

By A. Thies, A. Mezcer

The Haile mine is situated in Lancaster county, South Carolina, twenty miles south of Lancaster. The topography of the country is characterized by low hills rising generally less than two hundred feet above the many small creeks which traverse the surface. The road from Kershaw, the nearest railroad station, 3 1/2 miles from the mines, leads through woods with sandy soil and cottonfields. In many places it lies on the bare rock and shows that the adjacent covering of soil and earth is usually not more than one foot thick, and often less. This covering is to a great extent sand. Close by a bridge, about one mile from the mine, large round boulders of diabase may be observed. The country-rock seems to be exclusively talcose slate, with a general strike varying from N. 45' E. to N. 70' E. These variations may be seen in the immediate neighborhood of the mines, the large open cuts of which present exposures favorable to such ob-

Jan 1, 1891

By C. B. Barlow, T. A. Mekelburg

Due to a tight ash constraint on the clean coal product and difficult middlings washability characteristics, a considerable amount of coal was being lost in the jig middlings at the Monterey No. 2 Mine. An investigation was conducted into circuitry to recover this lost coal with minimal effect on the total clean coal ash. A reverse two-stage hydrocyclone system cleaning at low specific gravities was selected. This system is currently recovering approximately 5.8 kg/s (23 stph) of 11.5% to 12.5% ash coal. The specific gravity of separation for the system is about 1.5 and the probable error is 0.13.

Jan 1, 1986

By D. Hodouin, T. Gelpe

A digital simulator of classification and grinding circuits is used to evaluate the performance of various flowsheets. For a given flows he et configuration, unit process dimensions, and operating conditions, the simulator calculates the steady-state values of the process variables and determines the conditions that meet the required operation criteria for tonnage and product quality. Calculation examples are proposed for the design of wet and dry grinding circuits. The performance of different configurations of cement clinker and sulfide ore grinding flowsheets is evaluated and discussed.

Jan 1, 1986

By K. S. Seljesater

Since the development of dispersion-hardenable lead-antimony alloys' in the laboratories of the Western Electric Co., Inc., studies have been made of the effect of various third constituents on these alloys.2 This paper covers a study of the effect of small amounts of arsenic. This element is important since it occurs as an impurity in many commercial antimonial leads and the results obtained are particularly interesting as indicating a class of addition agents which exert a stabilizing effect on dispersion-hardened alloys. Experimental In order to study the effect of increasing amounts of arsenic, a series of alloys were made up containing 1 per cent. antimony, and arsenic varying from 0. to 0.10 per cent., the balance Doe Run lead (99.997 per cent. lead). The alloys were cast into bars 1 1/2 in. wide by 3/4 in. thick and cold-rolled to about 1/8 in- thickness. Three samples of each composition were annealed 1 hr. at 225" C. and quenched in water. One set was aged at room temperature, one at 50" C., and the third at 100" C., the

Jan 1, 1929

By P. H. Mell

The little village, from which this formation receives its name, is situated on a bluff of the Alabama River, 175 feet above water level. This bluff is a portion of high table land that begins in the western portion of Choctaw and extends through Clarke and Monroe counties. We find points on this ridge more than 100 feet higher than Tuscaloosa, and nearly as high as the Tennessee River at Tuscumbia. Through this the Alabama River cuts its way, exposing a beautiful cross-section of the strata, of which the accompanying sketch may give some idea. The fossils are found about 75 feet below the surface and 100 feet above the level of the river. There are seven distinct strata. 1. The lowest, extending from the water's edge up the bluff 80 feet, is a soft calcareous rock containing about 15 per cent. of carbonate of lime, with occasional specks of mica. In this a few Ostrea, Turritellæ, and Flustræ were found, but so friable as to fall to pieces when handled. 2. Next comes a stratum varying from 2 to 8 feet, consisting of

Jan 1, 1880

By K. S. Seljesater

Since the development of dispersion-hardenable lead-antimony alloys' in the laboratories of the Western Electric Co., Inc., studies have been made of the effect of various third constituents on these alloys.2 This paper covers a study of the effect of small amounts of arsenic. This element is important since it occurs as an impurity in many commercial antimonial leads and the results obtained are particularly interesting as indicating a class of addition agents which exert a stabilizing effect on dispersion-hardened alloys. Experimental In order to study the effect of increasing amounts of arsenic, a series of alloys were made up containing 1 per cent. antimony, and arsenic varying from 0. to 0.10 per cent., the balance Doe Run lead (99.997 per cent. lead). The alloys were cast into bars 1 1/2 in. wide by 3/4 in. thick and cold-rolled to about 1/8 in- thickness. Three samples of each composition were annealed 1 hr. at 225" C. and quenched in water. One set was aged at room temperature, one at 50" C., and the third at 100" C., the

Jan 1, 1929

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 Howard E. Parkinson, John N. Murphy

The past five years have seen communications techniques and hardware developed by the Bureau of Mines and its contractors increasingly brought into use in U.S. mines. The Bureau philosophy has been to help develop and introduce new hardware that goes as far as possible toward meeting the mining industry's needs. The Bureau programs are also designed to provide continuous fallout of new communications capabilities which are introduced to the mine operators as they occur. As more progress is made in meeting mine communications needs, it is hoped that the mining industry will readily adopt the equipment and techniques that it finds most useful in meeting its individual needs. This paper reports on recent advances achieved in the development of improved mine communications systems. In May 1975 the U.S. Bureau of Mines (USBM) conducted a mine communications technology meeting to provide a brief overview of the USBM communications technology developments in the past 5 yr. This meeting lasted for 1 1/2 days. Therefore, I have elected to narrow this paper to a brief review of recent underground mine communication developments. The following will be discussed: 1) Ultra-high frequency (UHF) radio for fan hole drill operators;

Jan 1, 1978

By C. Y. Chen

Public Law 95-87, the Surface Mining Control and Reclamation Act of 1977 (SMCRA), Section 516 (b), requires the underground coal mining operator to "adopt measures consistent with known technology in order to prevent subsidence cawing material damage to the extent technologically and economically feasible, maximize mine stability, and maintain the value and reasonably foreseeable we of such surface lands, except in those instances where the mining technology wed requires planned subsidence in a predictable and controlled manner.. . ." Congress also directed the Secretary of the Interior to promulgate regulations to implement the law. As a result, the control of subsidence from underground coal mining to minimize surface damage has become the mandate of a federal law. This paper discusses the mechanics of subsidence and the effects of subsidence on ground features. This paper also summarizes some measures used to minimize the possibility of damage to structures as a result of subsidence due to underground coal mining.

Jan 1, 1984

By R. D. MacDonald

The search for metalliferrous deposits in the Labrador-Ungava Trough of Canada dates from 1929 when non-ferrous minerals were the main quest of prospectors in this area. Many gossans, resulting from the oxidation of sulfides, were located and examined but none of these led to any orebodies of commercial value. However, such investigations did much to arouse interest in this area and fostered further mapping and prospecting. Since this early period in the history of prospecting in the Trough, the presence of iron ore deposits and potential iron producing sites has commanded the center of attention of exploration personnel. The iron-bearing rocks of southwestern Labrador have in recent years come into prominence as possible sources of iron ore of the beneficiation type. Exploration and development work has been carried on in concession areas granted by the Newfoundland Government to the Labrador Mining and Exploration Co. Ltd. and to the Newfoundland and Labrador Corp. In the course of evaluating its holdings in the Wabush Lake area (Fig. l), Labrador Mining and Exploration Co. has conducted geological, geophysical and diamond drilling programs.

Jan 10, 1960

By High Archbald

It is possible to construct a simple diagram of the earnings, or the production, of the men employed at a coal mine that will show not only if the conditions tend toward contentment among the men, but if the operating distribution of the work is correct. As earnings are the greatest cause of discontent, even exceeding all the other causes, if contentment exists in the matter of earnings, the likelihood of other discontents flaring up is greatly lessened. The basis of such a diagram would be the Gaussian curve of the normal variation in human ability. Such a curve has long been recognized. H. L. Moore,' in discussing the quantitative relation between wages and ability says: "It has been pointed out that industrial efficiency is dependent upon physical, mental, and moral qualities, and these qualities . . . there is good reason for regarding as being distributed according to the Gaussian law.

Jan 1, 1925