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R. W. NEWCOMB, New York, N. Y. (written discussion *).-In this paper, the author has enumerated the various sources of error that may, under certain conditions, develop in instruments of the direct-deflection type, but through a failure to mention possible sources of error in instru-ments of the potentiometer type, he leaves the reader with a wrong im-pression. If he would carry his criticisms further and give a list of the possible sources of error on potentiometer instruments, the paper would be more complete.

Jan 12, 1919

By I. P. Pardee

In our mixture at Musconetcong Iron Works we have an exceedingly hard, dense, magnetic ore, which contains some iron pyrites. The sulphur runs from 0.5 to 1.5 per cent. To prepare this ore better for the furnace, and with a view of making a softer iron, we tried roasting the ore in a Gjers kiln. When it worked well, the improvement in the iron was very perceptible ; but the ore was continually sintering and forming scaffolds across the bosh of the kiln.

Jan 1, 1887

By J. Ostachowicz, B. Holynska, M. Lankosz

The paper presents an analyzer and the method for the continuous determination of weight percentage of ore grains with diameter smaller than 75 pm in mineral slurries. The method is based upon the measurement of characteristic x-rays of copper excited by primary radiation of two different energies 16.5 keV and 60 keV from Pu238 and Am241 sources respectively. Additionally the backscattered primary radiation is measured in order to correct the variations of the solids content in the slurry.

Jan 11, 1979

By J. H. Rose

The arrangement of the reverberatory furnace and the two waste-heat boilers at the Magma Copper Company's smelter at Superior, Ariz., is shown in Fig. 1. The inside dimensions of the furnace at the slag line are: length, 96 ft.; width, 22 ft. The boilers are Erie City vertical type with a rated capacity of 700 hp. The 3-in. boiler tubes are arranged in two banks with a vertical baffle between. The banks are 30 tubes wide by 9 tubes deep—a total of 540 tubes.

Jan 1, 1934

Most lead-zinc mines worldwide have moved to further mechanized techniques to boost productivity, improve safety, and lower costs. The mining session, chaired by S. C. Fall, NL. Industries, and C. J. Beattie, Callahan Mining Co., reviewed mining methods at five operations in the US, Australia, Peru, and Japan. Where massive sulfide-type and irregular ore bodies are encountered, resourceful operators have modified and varied the mining method with the localized ore zones. In all cases, mechanization of operations has registered gains in productivity.

Jan 11, 1977

By John B. Pearse

THE works heretofore used in carrying out the Bessemer process have been constructed substantially as follows : The whole works or plant has been divided into three parts. 1. The division in which the metals for conversion are melted. 2. The division in which the metals are converted into steel and cast into ingots, or the converting department. 3. The engine and boiler department which supplies the hydraulic power required to move the machinery, and which furnishes the blast used for converting the crude metal into steel.

Jan 1, 1876

The current status of the US lead and zinc industries was reviewed by J. G. McCullough, president of Amax Lead and Zinc Inc. He reported that in the US, lead and zinc are separate industries because of the nature of mineralization. The large Mississippi-type zinc deposits are practically lead-free, and while the new lead belt in Missouri has some zinc content, it does not have the same favorable economic impact as in the complex massive sulfide ore bodies being developed elsewhere.

Jan 11, 1977

By T. F. Archbold, W. H. King

THE diffusivities of gold in polycrystalline copper have been determined in the temperature range from 700° to 1000°C by the utilization of the neutron-activation method. Martin, Johnson, and ~saro' used this method for their investigation of the diffusion of gold into copper at 375° and 550°C for 59 days in order to circumvent the experimental difficulties imposed by the 2.7-day half-life of Au-198. They employed the conventional technique of depositing Au-198 on copper specimens for short-time dif-

Jan 1, 1965

By Robert M. Lewis

At the Scotia plant of Blue Diamond Coal Co., near Cumberland Ky., good recovery and grade can be obtained when floating deep mine coal. When the plant changes over to strip coal, flotation fails, resulting in loss of coal. A procedure was developed at the Minerals Research Laboratory in Asheville, N. C., for recovering strip coal by flotation. Laboratory results were duplicated on a batch scale at the plant. The procedure was found to be effective when tried on a continuous basis in the processing plant.

Jan 1, 1973

By John F. Blandy

The map on Plate I illustrates a part of the works of the Red Bank Mining Company, on the Upper Freeport seam of coal, in Armstrong County, Pennsylvania. The contour lines give a careful representation of the conformation of the surface, showing also the line of outcrop of the seam, and the gangways of the mines are shown by the black lines. Upon assuming charge of the works in January last, I found that the first and greatest difficulty lay in the great uncertainty of the

By John F. Blandy

THE map on Plate I illustrates a part of the works of the Red Bank Mining Company, on the Upper Freeport seam of coal, in Armstrong County, Pennsylvania. The contour lines give a careful representation of the conformation of the surface, showing also the line of outcrop of the seam, and the gangways of the mines are shown by the black lines. Upon assuming charge of the works in January last, I found that the first and greatest difficulty lay in the great uncertainty of the

Jan 1, 1876

By R. W. Raymond

The name of Oswald J. Heinrich first appears among the members of the Institute in the first volume of its Transactions, which records that lie was elected at the Boston meeting, in February, 1873. That name has stood ever since upon our catalogue of active members. It has appeared frequently in the reports of our debates. It has been attached to many interesting and important professional papers. Henceforward it must hold a place, silent but significant, ill the pathetic lengthening list of our departed. From a present

Jan 1, 1886

A recent study estimates that a 10% improvement in the performance of wire rope used on draglines could save the US coal industry $2 million annually in rope costs. In addition, such an improvement could boost annual coal production by allowing the industry's draglines to remove an extra 1.5 million m3 (2 million cu yd) of solid overburden each year. These findings, although admittedly preliminary, suggest the magnitude of benefits that can be derived from a well-planned wire rope maintenance program.

Jan 3, 1978

By G. A. Perry, C. D. Iles

The philosophy used in designing and writing Duval's Sierrita mine design programs is discussed. The Sierrita Incremental Design system (SID) is reviewed with emphasis on Pushback Extraction Design (PED). PED is a method by which predesigned pushbacks are sequenced into an optimized period-by- period design. The design that PED Produces is the design used in the field without further modifications. The advantage of SID is that it provides a practical, mineable open pit design. PED is not a theoretical design system. It is in operational use.

Jan 1, 1984

By E. J. Wasp, T. C. Aude, F. B. Raymer

Abstract-The following paper deals with technical aspects of terminal facilities for western coal pipelines. The information is taken from the Ohio and Black Mesa pipelines and the proposed one in Wyoming. This paper first discusses the feed terminal, the product that it must produce, and the reasons for coal cleaning. Then, in the delivery terminal section, the various methods of dewatering the coal and some recent innovative ideas on bunkering the dewatered product and storing the dewatered coal in large outdoor piles are discussed.

Jan 2, 1978

By F. Milton Lewis, James L. Coburn

In this paper the economics for a conventional comminution system, consisting of three stage crushing and one stage ball mill grinding, are compared to a semi-autogenous/ball mill comminution system. Capital and operating costs for a copper concentrator in Arizona at two levels of production, 20 and 40 thousand short tons of ore per day, are estimated. In order to minimize the investment and operating costs, large size equipment is selected for all four cases. These cost data are evaluated and conclusions are presented.

Jan 1, 1982

By R. W. Smith, R. J. Charles

Fractions of glass particles in the size range 0.5 to 5.0 µ were prepared by an elutriator that operates in a centrifugal field. Although mean sizes of commercially graded abrasive powders were ten times greater than those of samples prepared by the elutriator, frequency size plots for elutriator samples compared favorably. Efficiency of separation was low and amounts of material recovered by the elutriator were small, but the method should find use in preparation of small amounts of sized materials for laboratory investigations.

Aug 1, 1956

For the third year in a row total value of the Nation's mineral production broke all previous records. A new peak of $20.4 billion was reached in 1964. So says the U. S. Bureau of Mines. The Bureau's preliminary estimate for 1964 is $800 million higher than the value reported for 1963, and $1.6 billion greater than the 1962 figure. The unprecedented demand for minerals, has stimulated development of new mines and expansion of processing capacity in many parts of the country.

Jan 2, 1965

By William M. Brewer

Since writing the paper on this subject,* which was presented at the Atlanta meeting in October, 1895, I have had opportunity for more thorough investigations in several localities, and venture, therefore, to offer some additional facts and opinions. The literature of the subject is not very abundant. Dr. George F. Becker's " Reconnaissance of the Gold-Fields of the Southern Appalachians "† contains some brief notes relating to Georgia, but does not include Alabama. The paper of Messrs. Nitze and Wilkens on " Gold-Mining in the Southern Appala-

Jan 1, 1897

By P. Somasundaran, Yee-Ho Wang

Carrier flotation of anatase impurities from clay using oleate is compared in this study with conventional flotation. The role of relevant parameters such as carrier size, carrier amount, dissolved calcium and carbonate, conditioning speed, pH, time and temperature and collector concentration is investigated in order to elucidate the mechanisms involved in carrier flotation. Addition of coarse calcite particles is found to contribute towards the enhanced separation of anatase from clay mainly due to aggregation of anatase fines with calcite and the subsequent flotation of the aggregates.

Jan 1, 1980