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By L. Holappa

Ferroalloys like FeCr and FeMn are mostly produced in submerged electric arc furnaces. Typical of these processes is that the amount of slag is quite high. The role of slag for the process is thus essential and specific chemical, physical and electrical properties are required. Slags in FeCr process are Al2O3-MgO-SiO2 based with minor contents of CaO and CrOx. Slags in the FeMn process are principally similar, originating from silicate minerals but can have quite large composition range depending on the manganese ore and its gangue minerals. Characteristic of the FeMn process is that the slag is rich in manganese oxide up to above 30%. A common feature is that the ?ore oxides?, CrOx and MnOx in slag are not only divalent oxides but also contain some higher valent of Cr3+and Mn3+, respectively. In FeMn production conditions the slag consists mainly of Mn2+. This is a clear difference from CrOx containing slags in which both two and three valent coexist in slags in FeCr process conditions. Oxidation state of the slag depends on the ambient oxygen partial pressure and temperature in the examined process. The thermodynamics of slags in ferroalloys, production are discussed in terms of phase diagrams, activities and oxidation state of chromium and manganese oxides. Further, slag properties influencing reduction kinetics and furnace operation i.e. viscosity and electrical resistivity are discussed. Keywords: review, slags, ferroalloys, ferrochromium, ferromanganese, thermodynamics, physical properties

Jan 1, 2004

By Parer W. R

During the last fifteen years there has been a marked change in the demand and supply patterns of coking coal. The world demand, predominantly Japan, has increased from 23 million tonnes of world export/import coal in 1960 to an expected total of at least 100 million tonnes by 1975. In the last ten years Australia has been the main beneficiary in the growth of the export coal trade. This has been brought about by its proximity to Japan and its large econ- omically mineable reserves of coking coal. A feature of the recent coal development in Australia has been the requirement of companies in new areas to provide massive capital for infrastructure costs. The ability of the Australian coal industry to retain a large share of the world export market depends to a large extent on reasonable costs to transport coal from mine to the market place. In some areas of Australia this means that railway lines, loading and unloading facilities, and ports will have to be up-dated at substantial costs. On the long haul to Europe the recent increases in the prices of bunker fuel have made the price of coal less competitive when compared with sources

Jan 1, 1974

By J. Zhang, T. Oleniuk

It is well-known that Saskatchewan has the world’s richest uranium deposits and advanced processing technologies. Unlike the Saskatchewan deposits, complicated mineralogy is common for other places in the world. Mineralogy dictates the process. Mineral Processing at the Saskatchewan Research Council has been working with the uranium industry worldwide since its inception to develop effective processing technologies to suit the unique mineralogy of each deposit. This paper reviews the research and development of uranium processing technologies in the current major uranium production areas such as Canada, as well as the potential development regions like Argentina and Sweden. Acidic and alkaline leaching processes, as well as by-product recovery technologies are discussed based on mineralogy.

Jan 1, 2020

By Mario J. Arenas Figueroa

El presente trabajo señala la formación geológica del yacimiento minero de Julcani, el fracturamiento de esta estructura, como los principales controles de su mineralización. En este sentido, la estructura del yacimiento es epigenético con vetas del tipo de relleno de fracturas en volcánicos Terciarios, caracterizadas por una mineralización en rosario y con valores de plata altamente erráticos. De otro lado, el fracturamiento es complejo puesto que este atraviesa tres periodos, las cuales coinciden con el rumbo de las vetas principales. Los principales controles de mineralización son el tipo de roca encajonante, los diques, intersecciones, etc, señalándose sus características para una exploración sistemática de nuevas vetas y bolsonadas.

Nov 20, 1967

By Parsons. Robert B.

"Starting this year, corporations that conduct business in Ontario face a new tax a corporate minimum tax. This tax is in addition to the myriad of other taxes that make up a corporation's total tax burden including federal and provincial capital 1oXJ!S, payroll tax and sales taxes. Mining companies with gross revenues in excess of $10 million or total assets exceeding $5 million may be liable for this new tax. IntroductionOn December 8, 1993, the Ontario government introduced legislation to implement the corporate minimum tax (CMT promised in its May, 1993 budget. There are very few differences between the final legislation and the budget proposals.The CMT is effective for taxation years commencing after 1993. Subject to certain specific exemptions (detailed below), the tax applies to all corporations liable for Ontario Corporate Income Tax that have either gross revenues in excess of $10 million or total assets in excess of $5 million. These measurements apply to the aggregate gross revenues and total assets for all corporations in an associated group and a corporate partner's share of partnership assets and revenues must be included in the determination.In essence, the CMT is an income tax that is based on financial statement profit instead of an income amount that is determined separately under a statute. Accordingly mining companies (including so called ""junior"" exploration companies), which traditionally sheltered their taxable income by claiming generous exploration and development deductions, could find that they have a CMT liability."

Jan 1, 1994

By J. L. Sepulveda, R. F. Yap, R. Jauregui

INTRODUCTION The Third Theory of Comminution, oftentimes called the Bond Theory, was first published by Fred C. Bond in 1952. Since then, it has been widely used in the milling industry to size crushing and grinding equipment as well as to predict and evaluate their performance. Although two other comminution theories were advanced almost a century earlier, one by Rittinger, 1867, and the other by Kick, 1885, their use was limited because they did not agree with actual commercial comminution systems (Bond, 1961). According to Bond's Third Theory, the work input is proportional to the new crack tip length produced in particle breakage, and equals the work represented by the product minus that represented by the feed. For particles of similar shape, the crack tip length is equivalent to the square root of one-half the surface area, and the new crack length is proportional to [(1/vT - vF)]; where P and F are particles diameter of product and feed, respectively. For practical calculations, the particle diameter can be expressed in terms of the 80% passing sizes, P and F, respectively. Therefore, the work input is given by, [10 _ 10', W = Wi [7P_7F(1)] Where W = the energy input to the mill, (kwh/t) Wi = Work Index, (kwh/t) P = square sieve opening which 80% of the product passes, (microns) F = square sieve opening which 80% of the feed passes, (microns) Equation (1) is the mathematical statement of the Third Theory, or the Bond equation. Numerically, the work index is the energy required in kwh/t to reduce a given material from theoretically infinite feed size to 80% passing 100 microns. The work index of a particular material is determined in the laboratory by conducting the standard Bond grindability test. Bond developed separate tests for the rod mill and the ball mill. The simplified test method described in this paper, which is used at Anaconda Research Center to approximate the work index, is an alternative procedure to the ball mill

Jan 1, 1982

By James S. Redpath

"The ways of the world be many and most of the ways be tried, you follow in the footsteps of others till you come to the great divide". These words, written by Robert Service a long time ago, come to mind when I think of our original attitude upon entering into a contract with the International Nickel Company to sink the deepest shaft in the world outside of the Union of South Africa. This shaft was to be sunk to a depth of 7,137 feet from surface, and while it was recognized by all concerned to be a somewhat unusual undertaking in our part of the world, the fact that quite a few shafts had already been sunk to this depth in South Africa probably gave us the feeling that we were following in the footsteps of others. In retrospect, because this shaft was being sunk under entirely different conditions than those existing in South Africa, we were in fact venturing into an entirely new area of endeavour without properly recognizing this fact. It has occurred to me that others considering a similar type of job could benefit from our experience, especially in an assessment of the risks involved and how they compare to those encountered in an ordinary shaft. For comparison purposes, I would define an ordinary shaft as being sunk to a depth of 5,000 ft or less, and a deep shaft as one being sunk to a depth of between 5,000 ft and 8,000 ft. The sinking of the Creighton No. 9 Shaft has been de-

Jan 1, 1997

By Moore A. J

This paper describes the use of a wavefront reinforcement model which has been developed to supplement established charge mass scaling methods. The model allows for the time taken for blast vibration wavefronts to travel from each blasthole, and has been successfully used to explain the reason for directional increases in both air and ground vibration in certain situations. The model has been used to identify wavefront reinforcement due to the propagation of air vibration and ground vibrations in certain situations. The paper includes a throw (or cast) blasting case history which provides multi-station evidence of the strong directional nature of wavefront reinforcement.

Jan 1, 1995

By Otto H. Henry

The purpose of this investigation was to determine the equilibrium diagram of the lithium-magnesium pair as a first step in studying the possible usefulness of these alloys as ultra-light structural materials. Review of the Literature The behavior of lithium towards magnesium was first investigated by Masing and Tammann.(1)† In order to prevent oxidation the alloys were made in iron tubes under an atmosphere of hydrogen; temperatures were measured with a glass-protected thermocouple. These investigators found that lithium and magnesium form two series of solid solutions separated by a miscibility gap between 85 and 95 per cent magnesium; that the alloys with 81 and 95 per cent magnesium showed a homogeneous structure under microscopic examination, while the alloy with 89 per cent magnesium contained two distinguishable crystallites; that the curve indicating the beginning of crystallization rises from the melting point of lithium to that of magnesium; and that no compounds of lithium and magnesium are formed. The equilibrium diagram was not plotted because no definite data were obtained for determining the solidus and the position of the miscibility gap in the solid state. The difficulties encountered in this investigation were: (1) that it was necessary to heat them as high as the melting point of magnesium in order to obtain homogeneous melts; at such temperatures the alloys attacked the glass protecting the thermocouple; and (2) that at temperatures above 400" C. the lithium united with the hydrogen to form lithium hydride, thus contaminating the alloys. By applying the same methods as those used in the lithium-magnesium system, Masing and Tammann determined the equilibrium diagram of the

Jan 1, 1934

By J. E. Zeilinger

This Bureau of Mines report describes the preparation characteristics of the significant coalbeds of the Ohio coalfield. Washability analyses were made on 39 coalbed samples collected from a 14-county area. None of the samples were of metallurgical quality as received. Nine of the samples could be sufficiently upgraded to produce metallurgical-grade products, and the remaining 30 samples could not be upgraded to this quality because their sulfur contents could not be lowered to meet the standard. For steam or power generation, 10 of the samples were of medium sulfur content as received and one could be upgraded to a low sulfur content. Of the 29 samples having a high sulfur content as received, 18 could be upgraded to a medium sulfur content. The original sulfur content of the other 11 samples having a high sulfur content as received can be appreciably reduced by removal of the sink 1.58 specific gravity material; however, these coals would be classified as high sulfur coals both before and after removal of the sink 1.58 specific gravity material.

Jan 1, 1972

By P. J. Ehret

By and large, I agree with many of the precepts discussed in the Saperstein paper. I believe there is much more that can be done on the local level to involve both government and planning in the mine permit review process. Admittedly, much can be done to improve discussion between the state regulatory authority, local authorities, and mine operators. However, I strongly disagree, as suggested in the paper's conclusion, that such a system, as outlined in Saperstein's paper, could result in a reduction of review time or a lowering in the cost of permitting. The implementation of such a system by its very nature would only add a new level of bureaucracy to an already cumbersome process. This system, in my opinion, would only add to the cost of permitting and the time necessary to obtain a permit. Admittedly, it would achieve the result of adding local influence into the permitting process, but at what off-setting cost? It has been my professional first-hand experience and observation in the permitting and lands unsuitable processes to note that under the present system, local governments that do feel they have a stake in local mines and actively advocate their position (not simply comment), have had significant input into the conduct of mining and reclamation plans in their areas. Mining companies that mine in these areas are aware of local interests and attitudes, and do consider them in their plans. Simply put, local governments that want to get involved and want to play significant roles can and do. Those that do not advocate a position or have no input to offer do not. Although the present system is not as direct in effect in regard to local control as Saperstein's, it does work. It does so without the red tape that would result from developing miniature regulatory authorities in every county in which mining occurs. Although local input is important, there are many more sections of the Surface Mining Control and Reclamation Act (SMCRA) than Sections 508(a)(8) and 522(a)(3)(A) that also are important. It appears Saperstein's paper may overindulge these sections. An additional specific comment is made in regard to the statement that while local areas benefit from mining (wages, salaries, and purchases), they also endure environmental deterioration caused by mining affects. It is believed that the whole purpose for which SMCRA and its resulting regulations were enacted and developed was so mining would not be permitted if significant environmental deterioration could occur. Therefore, it could be argued that this point under current law is moot.

Jan 1, 1985

By Gerardo Noriega

Aeromagnetic compensation plays an important role in most airborne geophysical exploration programs, dealing with the modelling and elimination of interference effects generated by the aircraft flying in the Earth’s magnetic field. This work discusses broadly recent developments on adaptive compensation (which allows continuous optimization of the solution through a recursive algorithm), real-time compensation of on-board electronic systems (whose effects are not captured by the conventional model), attitude-reference sensors, compensation of UAV platforms, and various modelling issues.

May 1, 2008

MR. GERALD ALLEY (C 11 i e f Draftsman, C. F. & I. Co.) : This invention is primarily intended to correct anything that goes wrong with the fan and any conditions in your air current underground which do not produce a change in your fan water gauge

Jan 1, 1925

By Sylvain Pirson

THE main value of earth magnetic measurements, outside of certain mining problems, resides in the study of deeply buried tectonic phe-nomena related to regional and local geology. Magnetic surveys are a necessary complement of gravimetric measurements, especially of pen-dulum surveys. To date, magnetometer, prospecting has been used chiefly in the study of sedimentary basins where petroleum structures are associated with the uplifted basement rocks. There are, in the literature, innumerable articles dealing with such surveys as applied to oil geology but few treat of broad geological features related to regional magnetic disturbances of the earth field. An important piece of coordina-tion work has been made by Jean Jung1 for the magnetic and gravimetric measurements made in France and their geologic significance. A similar attempt at correlation of the known geology with the anomalies of the vertical component of the earth magnetic field has been made for the United States by George B. Somers2. Taking the magnetic vector as a whole, W. P. Jenny' made a coordination of magnetism and geology for the main producing oil states of the United States. A more detailed study along the same lines is published by A. Van Weelden4 for southern Oklahoma and northern Texas; in this work magnetic and gravimetric measurements taken at stations as close as one mile apart are compiled and compared to the regional geology of the Ouachita-Amarillo uplifted area. From the literature mentioned, it is evident that reliable interpretation of magnetic anomalies can be arrived at only when the magnetic stations are numerous and cover the area in a close net of measurements, therefore the works of Somers and Jenny, based on sparsely distributed Government measurements, can be regarded only as preliminary programs indicating lines along which further work should be done, whereas the coordination made by Van Weelden is an example of the contribution to the knowledge of regional geology that can be arrived at by the use of applied geophysics.

Jan 1, 1935

By Grigore Matei

The thermodynamic properties of CuzS-FeS system are important not only in the ease of copper smelting but also in the case of general pyro-metallurgy. However there arc not many reported activity data In this study, activities of FeS and CU2S in the Cu2S-FeS system were calculated using the Darken's method from the activity data of the Cu2S-FeS-Sb2S3 systems measured by the transportation method at 1050°C. The activities of Cu2S and FeS in the Cu2S-FeS system showed negative deviation from the ideal behaviour and satisfied the relation of the Gibbs-Duhem equation.

Jan 1, 2003

By David G. Chedgy

It is probably safe to assume that most operating personnel working in coal preparation plants are exposed to noise levels in excess of the MESA Noise Regulations unless they are wearing ear protection. The excessive in-plant noise levels have received little attention until recently. Noise control has not been an important design consideration in existing coal preparation plants. This situation is rapidly changing as plant owners and plant operators are requiring that new coal preparation plants be designed to provide a safe noise environment for operating personnel and also meet MESA Noise Regulations. This paper discusses the noise exposure hazards, noise generating mechanisms, and some possible noise control solutions for typical coal preparation plants.

Jan 1, 1975

By Tammy G. R. Portela

A comparative characterization of the dimensional and mechanical properties as well as structural aspects of two different types of fibers extracted from the leaves and petioles of the buriti palm tree was performed. A statistical analysis revealed that both types of fibers present a significant dispersion in length and equivalent diameter. However, the corresponding intervals of dimensional variation are sensibly different. The tensile properties showed that both types of fibers display a tendency of higher strength for smaller diameters. Moreover, the fibers extracted from the leaves depict a comparatively lower strength. By contrast, the fibers from the petiole present an average strength sufficiently high for the use as reinforcement of polymeric composites. The structural aspects of tensile-rupture fibers, characterized by scanning electron microscopy, showed marked distinction in the microstructure and fiber behavior of both types of investigated fibers. This could explain the differences in mechanical behavior

Jan 1, 2010

To reduce air be respirable dust generated from emptying dry dust collectors on small truck-mounted drills used at surface coal mines.

Jan 1, 1995

By N. Aouad

The deployment of large machinery for low cost, bulk surface mine production operations has resulted in high-impact shovel loading operations (HISLO). In extreme cases, shovels load large dump trucks with 100-ton (or more) passes generating high-impact forces under gravity. HISLO generates high-frequency shockwaves that cause severe truck vibrations exposing operators to whole body vibrations (WBV). Current research study in this area has established that the vibration levels affecting the operator?s seat, lower-back, lumbar and cervical regions fall within the extremely uncomfortable zone compared to the ISO 2631 comfort zone. These results pose health threats to truck operators over long-term exposure to these vibrations. In this paper, the authors will examine engineered solutions to mitigate these health threats.

Jan 1, 2011

Current AG and SAG mill circuits have continued the trend to larger, fewer mills. These large mills place a significant additional load on the discharge systems and it has become imperative that the designs of these mill discharge systems are evaluated carefully to ensure maximum efficiency and have the capacity to be able to handle the increased mill discharge volumes. The current generation of multiphysics modeling tools allow a detailed analysis of AG and SAG mill discharge performance. The combination of Discrete Element Method modeling and Computational Fluid Dynamics allows the designer to model in detail all aspects of a mill discharge performance. This includes a detailed description of the build-up of solids and slurry in a mill discharge, the recycle of material back into the mill through the grates, the relative wear rates and the occurrence of overloading at the pinch points. These tools allow intelligent decisions to be made regarding the type of discharge arrangement, pan lifter geometry, and discharge cone design, so as to ensure that the discharge is capable of handling the duties required for a specific installation. This paper details the current state of the art in these modeling tools, and provides an overview of some recent applications.

Jan 1, 2012