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THE metal iron has physical arid chemical properties which are some- what different from those of steels, but a knowledge of the pure metal is a useful starting point in studying the behavior of steels. Solid iron exists in two different crystalline forms, called alpha (a) and gamma (?) iron the former being the ordinary form at room temperature. When heated above the "A2 point," 769 C (1416 F), the metal becomes nonmagnetic, and at the "A3 point," 911 C (1672 F), it undergoes a change in crystalline form to become gamma iron. 111 the range 769 to 911 C, it is sometimes called beta (ß) iron to distinguish it from the magnetic alpha, but the two are identical in crystal structure. When gamma iron is further heated to 1392 C (2538 F), it changes into delta (d) iron, which is identical with beta or nonmagnetic alpha iron. Pure iron melts (in an inert atmosphere) at 1536 C (2797 F); the melting point is generally lowered by alloys or impurities. PHYSICAL AND THERMAL PROPERTIES OF IRON Many of the properties of iron undergo abrupt changes at the transition temperatures.1 For example, in heating through the A3 point, a sudden shrinkage in volume occurs. Similarly, melting is attended by sharp physical changes such as an increase in volume. Table 16-1 contains a summary of the measured physical properties of pure iron at several temperatures. Usually the properties change smoothly with the range of stability of a given form, but this is not always true. For ex- ample, the specific heat reaches a sharp maximum at the A2 point al- though no transformation occurs. (See Fig. 14-1.) Solvent Powers of Liquid Iron. Liquid iron is capable of dissolving most of the other metals and many nonmetallic elements as well. Of the metals that are liquid at the melting point of iron, only lead, silver, and bismuth refuse to dissolve to an appreciable extent. Table 16-2 contains a list of the common elements classified with respect to their solubility in liquid iron. Those which are very soluble or practically insoluble require no further discussion, but several of the nonmetals that are gases and exhibit limited solubility are of considerable importance to us and merit more detailed consideration.

Jan 1, 1964

By Georgy A. Cherkashov

Two principal types of the hydrothermal fields in Atlantic - axial and off-axis - could be established based on their structural setting in the rift zone of the Mid-Atlantic Ridge (MAR) (Figure1). The first (axial) type is represented by five high- and three low-temperature hydrothermal sites (Table 1). All of these fields are connected with young axial effusive volcanism and related to large linear volcanic ridges or central volcanoes at the inner floor of the rift valley. The hydrothermal activity here is controlled by the intersection between longitudinal magma feeding faults and transverse weakened zones characterized by high permeability. [ ] The hydrothermal sites of the second (off-axis) type (such as Rainbow, TAG, 24°30?N, Logatchev, newly discovered 13°N (Figure 2) and possibly 16°48?N sites) are related to large tectonic dislocations forming marginal scarps of the rift valley as well as transverse discontinuities.

Jan 1, 2003

By M. J. Sapko

A moderately scaled apparatus was developed by the Bureau of Mines to determine the fire resistance characteristics of mine conveyor belts and similar type materials. The design of the apparatus was based upon data obtained in full-scale fire tests and features a radiant panel to preheat the belt and a methane-oxygen ribbon burner to ignite the sample under ventilating condi¬tions in a rectangular duct. The test method overcomes the limitations of existing laboratory-scale methods and provides a measure of both ignitability and flammability in quantitative terms. Flame propagation depended upon such variables as air velocity, ignitor heat flux, and belt width and height in the test chamber. Data are presented for nine belt materials and fire resistance ratings are proposed in terms of the flame spread rate, heat release rate, and the critical ignitor heat flux. The ratings discriminate between the fire hazard posed by different fire-resistant belts and tend to be in reasonable agreement with those obtained in full-scale fire tests.

Jan 1, 1981

By A. Azizi, P. Blatter, A. Bouajila

ABSTRACT In-situ monitoring of gold dissolution by means of a rotating electrochemical quartzcrystal microbalance unveiled dramatic decreases in gold leaching from sulphide-rich ore after 360 minutes in an actual cyanidation circuit. Pre-oxidation was effective in enhancing gold extraction by preventing a passive film from forming on gold surfaces. This work aims to highlight efforts undertaken to determine (1) how gold cyanidation is limited by passivation, (2) what reactions and mechanisms are involved during sulphide-rich ore cyanidation, and (3) how peroxidation efficiency of an industrial sulphide ore is controlled by galvanic associations between its sulphide constituents.

Jan 1, 2013

By Brian A. Ferguson, Raynald O. Vezina, Marielle Gaudet, Raoul R. Boissonneault

"Kiena has been committed to developing a fresh management and employee relations approach since the commencement of production in 1981. The functional organizational structure encourages joint participation and commitment on the part of all employees to common goals in safety and production. The results over the last four years have been extraordinary. Kiena won the John T. Ryan Canada Trophy for 1983 for its safety record and has experienced a steadily increasing productivity through the application of new mining equipment and technology in the hands of a well-trained and motivated team of employees.This paper serves to highlight the fact that productivity, safetyand technical innovation are closely linked to employee participationand involvement which are likely to be the key to theCanadian mining industry's survival in the years ahead.This presentation follows up on an earlier unpublished paper, given at the 84th Annual Meeting of CIM in Quebec City in April, 1982, which discussed the philosophy and the planning which took place before implementation of the management and employee relations system at Kiena. This present paper reviews and expands on material given in the earlier work. IntroductionThe mining industry, which has always been considered as rather conservative in its approach, has experienced with some regularity, cyclical periods related to metal prices. These cycles, previously foreseeable to some extent have become less coherent over recent years during which time the industry has had to face fierce international competition. The issue to productivity is without doubt the major concern of the mining industry in Canada today and it represents the greatest challenge facing us during the present decade. Developments that have been made in mining technology over the precious two decades have failed to completely produce the significant advancements in higher over-all productivity that were expected."

Jan 1, 1987

By R Edwards

Greater efficiency of capture of minus 6 mm to fine micron size particles of free gold is achieved with the Knelson Concentrator. The development, principles of operation and recent innovations relating to this enhanced gravity concentrating device are described by the inventor, followed by a description of application and consequent economic benefits in low grade alluvial gold deposits by a large scale user of Knelson Concentrators in the Northern Territory of Australia.

Jan 1, 1990

By R. L. Grayson, Y. J. Wang

This paper presents an application of goal programming (GP) to major mining machinery purchases based on historical operating data on mechanical downtime and production. The GP technique, an extension of integer programming, is used to maximize an objective function comprised of deviations away from management-preferred financial goals. Different capital budgeting techniques are used to evaluate capital proposals, and the results of these analyses are combined and weighted in a maximization of profits objective function. The GP method gives an optimal solution to a multiple goal problem. A sensitivity analysis is performed to determine the effect of a variable production improvement condition or a variable budget control con¬dition on proposal selection.

Jan 1, 1984

To date, improved thickening of clay mineral dispersions presents major technological and environmental challenge to mining and mineral processing industry worldwide. Flocculant-assisted dewatering processes currently employed during thickening are far from being efficient, requiring further development and process optimisation for dramatic improvement. In this paper, recent studies carried out to modify (i) pulp chemistry, (ii) flocculation performance and (iii) particle interactions to significantly improve the dewatering behaviour of flocculated, model and plant smectite and kaolinite clay dispersions are presented. It is shown that pulp pH-mediated hydrolyzable metal ion hydrolysis and specific adsorption in tandem with high molecular weight flocculant and shear may synergistically act to significantly enhance the dewaterability of both clay mineral pulps. Furthermore, polymeric flocculant structure type is demonstrated to show clear links with floc shear sensitivity, and hence, flocculation performance and pulp dewaterability. The implications and relevance of the findings plant clay mineral waste tailings thickening operations are drawn.

Jan 1, 2006

By Joseph Sofra

It has become increasingly evident that sustainable metals production in the 21st century requires producers to balance the needs of cost effective, high value production with that of responsible plant operation. This is becoming more difficult as lower grade and more complex feed materials, including recycled scrap and residues, are being processed to reduce production costs and decrease exposure to primary metal market fluctuations. One particular facet of the metals industry facing these challenges in the 21st century are copper producers, The recent steady decline in the copper price has seen the industry cut expenditure, tighten control on income streams and focus on high returns on capital investment. For these reasons copper producers are looking towards flexible technologies that can deliver high value products, with minimal environmental impact at low capital and low sustainable operating costs. Ausmelt's Top Submerged Lancing (TSL) technology for copper production is a low cost, proven technology for the processing of both primary and secondary copper materials. Both the smelting and converting operations introduce significant advantages in environmental performance, improved process efficiencies and high rates of metal recovery, Ausmelt has made significant gains in the past 4 years in establishing a strong market position for its copper technology, New installations in China, South Africa and India as well as existing operations in Zimbabwe and China have demonstrated its effectiveness. This paper reviews the application of Ausmelt Technology for both smelting and converting of primary and secondary sources, It discusses Ausmelt's design and implementation philosophy, and how this philosophy meshes with the needs of the end user.

Jan 1, 2003

By M. W. Grodner, J. Maaren, G. Guler, J. K. Schweitzer

The selection of the most suitable mechanized mining strategy has to consider the geotechnical environment in which it will be operating. A mechanized mining method or machine is designed to a given set of specifications to work within an environment. The geological conditions that define this environment are fixed—detailed information of these conditions for design specifications is thus critical. Two major classes of geotechnical parameters are defined—critical and design. The critical controlling factors are a result of mineral composition, size, shape, abundance, assemblage and associated texture, as well as discontinuity type and orientation. Design parameters are specific to each deposit, and their nature cannot be broadly described, as with the critical factors. It is shown that for major deposits in South Africa, namely the Witwatersrand Basin (gold), the Bushveld Igneous Complex (PGEs) and the Karoo Coalfields that by incorporating geological and geotechnical information that appropriate mechanized mining methods can be deduced, and that the performance and design parameters of specific technologies can be determined

Sep 1, 2001

By J. P. Mogan, E. D. Dainty, A. Lawson

"The toxicity reduction of emissions from two diesel engines by the emulsification of water into fuel oil was investigated to determine the applicability of such systems to underground mining machinery. . The engines studied were: 1) the Deut; F6L7J4, four-stroke, air-cooled, 6-cylinder, V-configuration, indirect-injection (IDl) engine, and 2) the Detroit Deisel Allison Division 8V7JN, two-stroke, water-cooled, 8-cylinder, V-configuration, direct-injection (Dl) engine.The application of emulsified fuel treatment to the two-stroke engine did not prove to be practicable. In the case of the Deutz engine, however, substantial benefit resulted. For a modest J5 per cent water content in the fuel and an injection timing of24° BTDC, approximate reductions of40 per cent in the concentrations of both particulate matter and nitric oxide (NO) were produced. These reductions were accompanied by insignificant changes in other toxic constituents. The net result was an approximate 30 per cent reduction in the over-all exhaust toxicity for typical LHD operation as assessed by the Health Effects Index criterion. This toxicity reduction represents a significant advance from the points of view of an improved underground environment and/or reduced ventilation costs."

Jan 1, 1981

By Eugie Kabwe

Rock bolts are components of tunnel support structures and their efficacy in reinforcement requires the appropriate estimation of the bolt pre-tension. However, cases of ineffective rock bolt application due to loosening are common which leads to the potential failure of the support structures, thus negatively affecting the tunnel stability. The effective employment of pre-tensioned bolt within support structures requires an appropriate installation tension as a result of sufficient bolt head/nut pre-load. Henceforth, this paper presents a load indicator washer (LIW) capable of withstanding assigned static loading as well as provides an appropriate pre-tension. The different LIW breadths are numerically analysed in the finite element code (ABAQUS) to estimate deformation when a designated 60-kN pre-load is applied. The numerical simulation employs a bi-linear isotropic hardening constitutive law governed by the von Mises yield criterion. The simulation also considers the nominal temperature of the nutLIW-rock bolt connection. Therefore, a long-term relaxation effect on bolt pre-tension as a result of stress relaxation is neglected. The compressive force required to achieve the LIW-predetermined deformation is the bolt pre-tension. It is drawn from the simulation results that the 1.5-, 2.0-, 3.0-, 3.5-, and 4.0-mm-thick LIWs are completely flattened when subjected to 28-, 42.5-, 65-, 76-, and 88-kN pre-load respectively.

By Nic Slatalla

Acoustic emission monitoring techniques are a powerful tool for analysing deformation behaviour and fracture characteristics of rock samples under uniaxial loading. Uniaxial compression tests were carried out on three different types of sandstone for a better understanding of acoustic emission response with respect to rock deformation and damage develop-ment. All sandstone samples revealed congruent characteristic acous-tic emission patterns which correlated directly with distinct stress-strain stages. However, the acoustic response and development within the individual stages proved to be entirely different due to variations in their microstructure.

Jan 1, 2008

By Fred N. Kissell

Experimental work by the Bureau of Mines indicates that when a coalbed is degassed by boreholes, the flow of methane may actually increase with time. This phenomenon appears to be the result of a relative-permeability effect; that is, the coalbed permeability to the gas increases sharply with decreasing water saturation. This report reviews the background of experimental evidence indicating a relative-permeability effect, and presents the results of a computer simulation of two-phase flow in coal.

Jan 1, 1975

There are many types of environmental audit: compliance, impact, risk and management audits; internal and external audits; single and multiple-project audits. All are becoming increasingly important in corporate management as new legislation confers increasing personal liability on directors, executives and staff of corporations and agencies in both private and public sectors.

Jan 1, 1990

By D. W. Hendriks, C. Daoust, K. V. Konigsmann

"The concentrator of Mattagami Lake Mines Limited commenced operation in 1963. It had been designed with instrumentation proven at that time. New control techniques were added in subsequent years.An on-stream X-ray analyser was installed in 1968. It provided circuit analyses for six years without the aid of a computer. In late 1974, control of the flotation circuit by computer was incorporated into the system. Flotation efficiency improved considerably, zinc"" recovery increased by one percentage point and concentrate grade by four-tenths of a percentage point. Reagent costs decreased modestly through reduction of copper sulphate consumption."

Jan 1, 1976

By R. Norman Orava

The strain-mte behavior of. the tensile yielding and flow characteristics of arc-cast polycrystal-line molyhdenum of pidrity > 99.97 pct was investigated in the range 10-6 to 10-1 sec-1 at 243o, 293o, and 373oK for two grain sizes, 0.027 and 9.098 mm. For 0.998 mm, the strain-mte dependence of the lower yield stress can be described by a straight line of the jowl a, = a + 0 log e over the whole range of strain rates examined. However, for 0.027 mm, the data fit several consecutive linear relationships of the above form. The previous association of these different linear regions with different rate -controlling mechanisms is questionable for molyhdenzdm. The senlilog strain-rate dependence of the yield stress is consistent with Hahn's model for yielding when the stress dependence of the mobile dislocation density, pr, is taken into account. Since p', from rate -cycling experirnents, is found to be relatively insensitive to stress for single crystaIs, the obserzied log-log dependence of their yield stresses is also in agreement with the model. A correction for the stress dependence of p' changes the activation oolurrze for yielding from a zero to a more realislic inverse function of stress where the Peierls mechanism is believed to be rate-controlling. The gmin-size dependence of the lower yield stress is not a monotonic junction of strain rate. RECENT experimental evidence' has revealed that the strain-rate dependence of the tensile lower yield stress, a,, of commercially pure ni- obium and tantalum tested at room temperature can be described by several consecutive semilog relations of the form: sv =a + ß log € [1] where i is the applied strain rate and a and 0 are constant Over only relatively small ranges of strain rate. Three linear regions were found for niobium and four for tantalum. Each linear region was interpreted as being associated with a different rate-controlling mechanism on the basis of the current

Jan 1, 1964

By A J. H Newell

The background and the basis for conducting a Technical Due Diligence are discussed as well as the source information, typical studies and potential limitations. Typical short comings including ‘show-stoppers’ are presented for the metallurgical area, with examples. Issues found in other areas such as geology, mining, infrastructure and financial evaluations are briefly reviewed, highlighting the input and interaction required by metallurgists with these disciplines. A checklist is provided as a guide to maximise the success of a Due Diligence as well as a check on the quality of a Feasibility Study.CITATION:Newell, A J H, 2015. Fatal flaws in technical due diligences, in Proceedings MetPlant 2015, pp 61–77 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 7, 2015

Jan 1, 1968

By K. C. McMahon

This report is the result of the engineering efforts performed by the Mining Equipment Operations of FMC to develop methods of automating a continuous miner. This work was done as part of modification number three of the contract for the development of a miner/bolter system. As the demand for energy places an ever-increasing pressure on the coal mining industry to produce more coal, methods for underground mining which will increase productivity with a con-current increase in safety are being actively sought. Removing the machine operator from his station on the continuous miner and placing him at a safer location behind the machine while retaining his control functions via an umbilical cable or a radio link was an important first step. However, the problems of poor visibility, no control "feel", and the judgmental problems of controlling the sump distance and the shear limits have not been conducive to the productivity increase that is desired.

Jan 1, 1975