Search Documents

By Carl Wagner

J. Pearson (British Iron and Steel Research Association, London, England)—Dr. Wagner has referred to the work of Richardson and Dancy and Gellner and Richardson on the reduction at 900 °C of wiistite films on iron. He has assumed that iron ions and electrons migrate backwards to the iron-wustite interface and that the reduced iron grows on the metal substrate. This would be a possible explanation of the results of these workers were it not for the fact that, as stated by Gellner and Richardson but not stressed, this growth in the center of the specimen can occur even

Jan 1, 1953

Three meetings of the Institute for the presentation and discussion of technical papers were held in 1913: The 104th meeting, comprising the Annual Business Meeting as well as technical sessions, was held at New York, Feb. 18 to 20, 1913; the 105th meeting was held at Butte, Mont., Aug. 16 to 21, 1913, at which papers obtained largely through the efforts of the Committee on Precious and Base Metals were presented; and the 106th meeting was held at New York, Oct. 16 and 17, 1913, under the auspices of the Iron and Steel Committee.

Jan 1, 1917

Recognizing the fact that the problems of the committee named by the Board to prepare the "official ticket" for officers and Directors of the Institute are various and difficult; and desiring to assist this committee by setting forth some of the principles that should guide the committee and some of the qualifications that should be required of candidates, the following instructions are formulated and the Secretary is directed to publish them in MINING AND METALLURGY concurrently with the publication of the names of each newly appointed Nominating Committee and to send a copy to each member of the, Committee.

Jan 1, 1946

Recognizing the fact that the problems of the committee named by the Board to prepare the "official ticket" for officers and Directors of the Institute are various and difficult; and desiring to assist this committee by setting forth some of the principles that should guide the committee and some of the qualifications that should be required of candidates, the following instructions are formulated and the Secretary is directed to publish them in MINING AND METALLURGY concurrently with the publication of the names of each newly appointed Nominating Committee and to send a copy to each member of the Committee.

Jan 1, 1946

By J. D. Vincent, Paul A. Weyler

Climax Molybdenum's plan for the Henderson 30,000 tpd molybdenite plant didn't just happen. It slowly evolved over a period of 3% years. Many plants cannot afford similar delays, but the Henderson project will take about 10 years to complete from the time the orebody was first discovered until production begins. Pilot plant testing results with both the single stage and two-stage semi-autogenous grinding circuits were highly favorable in terms of operating costs reduction-so much so, that the Amax subsidiary made the decision to go with semi-autogenous grinding for the Henderson mill.

Jan 5, 1972

By R. C. Dorward

DIFFUSION considerations are necessary to describe many technologically important metallurgical and physical processes. Since most commercially important alloys are comprised of more than two components, diffusion calculations applicable to binary systems are often unjustified. However, in many instances the more general equations valid for three-component systems may be employed. The phenom-enological description of ternary diffusion is now well-established,1-4 and the theory has been applied with some success to a few practical situations.5"7 The flux equations for the solutes (components 1 and 2) of a ternary solution may be expressed by:

Jan 1, 1969

By F. A. Kjellin

The problem of smelting steel by electricity attracted years ago the attention of inventors, and as early as 1879 C. W. Siemens constructed his first furnace for the smelting of metals, especially steel. His furnace was of the arc type in which the voltaic arc was formed between a carbon electrode and the metallic content of a crucible, the length of the arc being regulated by an electromagnetic device. This electric furnace, as well as others of similar construction, has the inconvenience that the source of the heat—the voltaic arc—possesses a temperature of 3,700' C., which is much

Jan 1, 1904

By G. Don Sullivan

Surface mine operators have organized a voluntary group known as the Mined-Land Conservation Conference for the specific purpose of developing and expanding reclamation programs on mined land. As a part of the Conference program, a Voluntary Industry Program was adopted and subscribed to by its membership. This program stated: "The basic approach to a sound conservation program is the restoration of mined land to its most practical and productive use within the shortest possible time . . . reclamation of mined lands, including planting to grasses or tress, should be done on a planned basis, under technical guidance by personnel trained in this field."

Jan 7, 1965

Improvement of drilling operations through the development of new, unconventional drill bits is a prime research target at Sandia Laboratories, Albuquerque, N.M. Sandia is currently focusing efforts on four new bit designs which its engineers believe may eventually improve penetration and reduce operating costs. The Energy Research and Development Administration (ERDA) has budgeted $500,000 in support of this program to date. Two of the drill bits-one that chips rock with high voltage spark discharges, and another which fires small projectiles into the rock ahead of a regular roller bit-are designed to increase both penetration rates and downhole bit life.

Jan 8, 1975

By A. Kavetsky, W. J. Whiten

Data from ball mills with a wide range of diameters are analyzed using detailed mathematical/ numerical models. Analysis shows the relative power inefficiency of large ball mills is due to their inefficient breakage of coarse particles. The models developed can be used to scale-up mill behavior. The behavior of large mills at Bougainville and Pinto Valley is compared. It is concluded that the mills are equally inefficient at grinding coarse particles. Differences in coarseness of total mill feed are shown to account for the fact that Pinto Valley mills achieved design throughput whereas Bougainville mills did not.

Jan 1, 1985

By Neil Styler

This paper presents an analysis of measurements of inter-burden deformations above six longwall faces. An attempt is made to demonstrate some correlation between the movements at the various sites, and to examine their importance with respect to predicting caving height, disruption of overlying seams, and disruption of aquifers. This analysis demonstrates some significant differences between predicted surface subsidence, and inter-burden deformation. In addition it is shown that the caving height above a longwall face is equal to 8 to 12 times the extraction height, with a zone of fractured rock extending to approximately 50 times the extraction height above the seam.

Jan 1, 1984

By Christopher M. St. John, Michael P. Hardy

The paper discusses an approach to geotechnical monitoring of a geological repository constructed for the purpose of isolation of high-level nuclear waste, and describes the conceptual framework for development of an integrated monitoring scheme that is initiated during the earliest phases of site investigation and continues through facility decommissioning. The approach that is proposed recognizes the need to provide specific data to support the licensing process for the repository while avoiding adverse impact upon the system performance. Further, it recognizes present and inherent limitations in both the instrumentation and techniques that night be used within a monitoring scheme.

Jan 1, 1982

By D. R. Skidmore, C. J. Konya

To quantify the effects of proper stemming on air-blast and flyrock reduction for a surface mining operation, a study was undertaken with funding from the Office of Surface Mining. Known weights of explosive charges were detonated in a simulated blasthole when confined with various types and size distributions of stemming. Results showed that proper selection of material type and size distribution can reduce necessary stemming length by 41 % and airblast levels by 23%. A relationship was obtained for minimum length of stemming for explosive confinement as a function of stemming size distribution and borehole diameter over a range of explosive pressures.

Jan 1, 1984

By P. L. Lavery

A numerical method to derive approximate solutions for stress intensity factors for rectilinearly anisotropic bodies without resolving to complex variable approach is presented. The method is based on the assumption that the crack opening profile can be simulated by a simple curve such as an elliptic function and a relationship is found for the stress intensity factor in terms of near tip displacements. An example solution is derived for a transversely isotropic body and the results are verified with Westergaard's stress function approach. The proposed model has a great potential for the applications to fracture mechanics of anisotropic rock materials.

Jan 1, 1984

By Ronald J. Roman

All mining and milling complexes can, within limits, operate at a variety of production rates. Factors of economic importance that are affected by production rates are costs per unit production, recovery, and product grade. Once the relationship between the production rate and cost is established, dynamic-programming techniques can define the optimum production schedule (i.e., the production schedule that maximizes the present worth of the operation) for the life of the deposit. In general, the optimum production rate is not constant for the life of the deposit, but declines gradually as the deposit is being exhausted.

Jan 1, 1972

By R. Schutte, L. W. Trevoy

Commercial production of heavy minerals from plant tailing streams is undergoing study by Syncrude Canada Ltd. When tar sand from an open pit mine is processed and upgraded to synthetic crude oil, heavy minerals can be recovered from the extraction circuit and can be upgraded to provide concentrates of zircon and titanium minerals. The titanium minerals concentrate, consisting of a mixture of ilmenite, leucoxene, and rutile, can be utilized as recovered or can be upgraded to synthetic rutile. With the construction of further synthetic crude oil plants in Western Canada a large reserve of heavy minerals will become available for production.

Jan 1, 1983

By N. A. D. Parlee, M. T. Utine

ThE kinetics of absorption of oxygen by induction-stirred liquid silver (at constant Po2 and T) has received some study here.''2 This paper describes a study of the kinetics of effusion (non-bubble-forming), and some additional work on absorption. A Sieverts type of apparatus was used. The kind of reaction tube assembly has been described.4 The same 25-kw, 450-kc induction unit was used as in earlier absorption work1'2 but the "coupling" was different. The runs were made under the following conditions: i) saturation at 1 atm, effusion at 0.81 atm;

Jan 1, 1969

By D. A. Singer

A procedure whereby the completeness of search is calculated by using the area of influence of exploratory drill holes or samples is extended to allow for errors of recognition. The size, shape, and orientation of potential targets are mapped in a probabilistic sense on the array of drill holes or samples. The method can be used either to determine how well explored are the subregions within a previously drilled or sampled area, or to test proposed alternative search strategies. Examples of the use of the method demonstrate the complexity of sequential search when the areas of influence of drill holes or samples overlap.

Jan 1, 1976

By Helmar Schubert

The tensile strength of moist agglomerates consisting of granular materials is demonstrated with the aid of models. The applicability of these models is proved by experiments. An explanation of the different values of strength of imbibed and drained agglomerates is given and it is shown that the maximum tensile strength occurs at the so-called entry suction. The entry suction, which can be considered as the characteristic capillary pressure of the agglomerates, is described in terms of its parameters by a dimensional analysis. The influence of porosity is determined experimentally by means of regressional analysis and is compared with known model equations.

Jan 1, 1977

By E. A. H. Tays

At the present time, the mine-owner has a number of patent crushers to choose from, when contemplating the erection of a mill; and a number of new ones are yearly brought to notice. We all know that the stamp-mill is the old standard; but several of the patent crushers, especially of the roller-type, are not without their merits. Having had a working experience, extending over a period of four years, with the " Bryan roller quartz-mill," working alongside of stamp-batteries, I take pleasure in giving to the members of the Institute the benefit of my experience with this mill.*

Jan 1, 1900