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By Jaroslav Horskoý, Miroslav Raudenský, Bogdan Filipic, Božidar Sader

This paper describes main elements and practical use of the computational system for automated setting of optimized casting conditions in the continuous casting of steel. The system consists of the heat transfer model of the process, empirical metallurgical criteria, and optimization algorithm. The physical model of the, strand temperature distribution relies on the classical Bennon-Incropera mixture continuum formulation for the convective-diffusive heat transport. Fluid flow effects are considered through enhanced thermal conductivity of the liquid phase. The model is solved by the operator-splitting Crank-Nicolson finite volume version of the Voller-Swaminathan scheme. The solution procedure is coupled with the IDS solidification analysis package. Boundary conditions for the strand cooling rely on combination of the generic and plant-specific mold, spray, and roll heat transfer coefficients ' by coping the effects of the casting speed, casting temperature, casting powder, mold oscillation mode, steel grade, water or air-mist spray type, running water, trapped water on the rolls, and radiation. The caster safety and productivity and the quality of the strand are related to nine empirical metallurgical criteria. The criteria ensure the caster safety and economy as well limit the internal, longitudinal, and transversal surface cracking possibility. The problem of finding optimum casting parameter values is stated as a minimization problem based on the analytical form of the cooling criteria evaluated from the steady-state temperature distribution of the strand. To solve the optimization problem, a genetic algorithm is employed. The algorithm explores process parameters settings heuristically by applying the principles of biological evolution. It starts with a random set of solutions and iteratively improves them through selection and variation. Solutions are evaluated by running the heat transfer model of the process and extracting the values of the empirical metallurgical criteria.

Jan 1, 2000

By Chris M. Healey

"Abstract - Perhaps the single most significant variable in the evaluation of a mining project is the reserve estimate. Many parameters are considered when estimating reserves, among them geology. This paper examines the link between the quality of a reserve estimate and a good understanding of the geological controls for the deposit. A clear understanding of the geometry is essential to the accurate definition of the shape and size of the deposit. This includes the definition of any structural controls as well as the proper interpretation of the stratigraphy. Further when the distribution of grades is erratic and there is consequently a high nugget effect, there are significant problems in estimating the true grade of the deposit.Two Saskatchewan examples are presented, one with good knowledge of the controls and therefore good estimates of reserves, and the other with a poor understanding of the geology and resultant problems in deriving good estimates. In both cases the reserve estimates at various stages in the project development are compared to actual results from underground work. The first example is the Star Lake Mine where just about all the estimates were within 10% of the actual on both tonnage and grade. The Laurel Lake deposit is discussed to show how problems in interpreting the geological data make reserve estimation very difficult. Laurel Lake has the additional problem of erratic grade distribution."

Jan 1, 1992

By H. W. Wevers

Fatigue failure and accompanying brittle failure occurs frequently in heavy mining equipment. This paper discusses how fracture mechanics can be applied as a tool for crack control and crack management. Information is provided to determine if particular components are prone to brittle failure. By using existing fracture mechanics formulae, an estimation of the critical crack size can then be made. It is explained that for a successful application of fracture mechanics, both the actual engineering stress in the component and the mechanical properties of the applied material must be known. The importance of toughness at low temperatures is quantitatively illustrated by calculating critical crack sizes at room temperature and at below-zero temperatures. Understanding the possibilities of fracture mechanics will also produce a climate in which the purchaser of equipment can more precisely analyze the relative quality of components with respect to crack tolerance and failure prevention. In this manner, communication between the user and manufacturer of equipment may also become more precise and effective, leading to improved design.

Jan 1, 1977

By Xue Yang

Even though many approaches have been proposed for automated fault detection and diagnosis of Heating Ventilation and Air Conditioning (HVAC) systems, and advanced maintenance programs, such as preventive and predictive maintenance have been applied for the systems, issuing work orders for corrective maintenance is still a reality. Currently corrective maintenance still accounts for more than 55% of all maintenance programs in average facilities in the US (DoE, 2010). Indoor air related problems are especially important among corrective maintenance work orders. This paper provides details of a case study conducted to capture the workflow that HVAC mechanics follow, their rationale in diagnosis process and the information they typically refer to while responding to indoor air related corrective maintenance work orders. The general workflow for HVAC mechanics to complete such types of work orders was summarized into 5 stages, and generic information requirements recorded from the case study were synthesized. Initial findings show two main challenges in the industry for HVAC mechanics to get access to required information, which highlights the need for a systematic approach that would enable identification of such information applicable to a given context under which a work order has been generated and provide values of required information for HVAC mechanics to do sound diagnosis through integrated data repositories.

Aug 1, 2013

By T. Sterry Hunt

Jan 1, 1884

By John F. Dougherty

Recently, there has been much debate as to the relevance of reporting financial results using the conventional accounting systems, which is based on historical costs, during a period of rapid inflation. In the following paragraphs , the symptoms, if not the causes, of inflation, its detrimental effect on the financial soundness of business in general and the financial reporting changes being advocated to overcome perceived weaknesses in the present financial reporting system in accounting for the effects of inflation will be reviewed. Finally, a course of action as a sound approach to the financial reporting problem will be recommended.

Jan 1, 1978

By J S. Laskowski

Froth flotation process requires the use of frothers. These important flotation agents are commonly characterised as either æselectiveÆ or æpowerfulÆ and are chosen following general guidelines and verification by laboratory and/or pilot plant tests. Fundamental properties of the flotation frothers have been extensively studied over the last few years. These studies have led to the development of standardised procedures to characterise frothers in terms of their ability to reduce bubble size and to increase foam stability. In this research project, the performance of five frothers in flotation of coal is evaluated and related to the fundamental properties of these agents. Since the recovery of water in the concentrate is closely related to the non-selective transport of solid particles by entrainment, the tested frothers are also assessed in terms of their ability to promote the transport of water towards the froth collection zone, both in absence and in presence of solids.

Jan 1, 2005

By E. G. Leonardon

The question of geophysical prospecting is one that is beginning to occupy a pre-eminent place in the minds of those actively concerned in the discovery and exploitation of ore deposits. This is in marked contrast to the reception accorded such ideas when the Junior author, six and a half years ago, began introducing electrical prospectii1g to the mining fraternity on this continent. Happily, the mention of geophysics no longer evokes the sceptical and pitying smiles that it did in those days. A little reflection will show that modern geophysical methods are merely a logical development from pre-existing technique. In the study of geological problems, is it not logical to use all possible physical properties of matter? The study of crystal form and cleavage, the examination of thin sections of minerals by means of polarized light or ordinary light, in fact, utilize physical properties of minerals for the benefit of the geologist. These are, of course, laboratory methods, and the extension of the study of similar properties into field work was inevitable. This began with the magnetometric surveys, used as early as 1760 in New Jersey to locate iron ores. Eighty-four years later, John Locke's work in the United States resulted in pointing out relationships between the terrestrial magnetic field and main tectonic features of the earth's crust.

Jan 1, 1928

By Matthias Neuenschwander, Andreas Theiler, Patrick Steinle, John Singer, Martin Vogel, Diego Martini, Ömer Ündül, Markus Weh

"Quartz Dust is a major health hazard in underground works, wherever the ground contains quartz and depending on the chosen method of excavation. A research project initiated by the Swiss Tunnelling Society and realized by the Swiss Federal Institut of Technology, Zurich, established a correlation between the potential of quartz dust generation during excavation and well known geotechnical characteristics – the Cerchar Abrasivity Index CAI and the Uniaxial Compressive Strength UCS - of ten typical Swiss rocks. The results are at the center of a new guideline by the Swiss Society of Engineers and Architects on the requirements for early project stages regarding ventilation and logistics in function of the quartz dust related risk of the expected ground type of the project. The approach presented could be applied worldwide, contributing to more effective health protection as well as to better cost stability in underground works. CONTEXT Respirable quartz dust (aerodynamic diameter of particles < 10 micron) is universally recognized as a major workplace health hazard. Chronic bronchitis, silicosis and lung cancer can be caused by excessive exposure to quartz dust, as has been proved by many medical studies. Therefore, the legislations of many nations specify a maximum workplace concentration (Maximale Arbeitsplatzkonzentration MAK, Occupational Exposure Level OEL). In Switzerland, for example, the Threshold Limit Value TLV for respirable Quartz or Crystalline Silica imposed by the Federal Committee on Exposure Levels (Grenzwertkommission) is 0.15mg/m3 air. Some nations refrain from establishing a OEL because of the carcinogenic nature of quartz."

Jan 1, 2016

By Sureshan K. Moothedath

This paper provides a mechanistic representation for floc formation, growth and degradation and presents results from an experimental study of batch flocculation in which step changes were made in the impeller speed, flocculant addition, and slurry concentration. A discussion of the experimental results is included in terms of the mechanisms of floc formation and size-change.

Jan 1, 1993

By W. A. Crosby

All mine operators using explosives want to maximize explosive performance while minimizing blasting costs. Use of bulk explosive products such as AN/FO, heavy AN/FO, slurries and emulsions has greatly improved blasting efficiency over the years. Many operators have improved energy output from these products by adding aluminum. A major problem facing them is the fluctuation in aluminum price. The question therefore becomes, when is it economically advantageous to use aluminum in bulk products? This paper answers this question by first reviewing the energy output from the main types of aluminized and non aluminized bulk mixed explosives and then by showing the relationship between the different products on a cost and energy basis. The paper finally presents examples of charts and tables which will aid mine operators to conveniently select the most economically correct bulk explosive, including the level of aluminum addition.

Jan 1, 1991

By Steve Zaffron, Olga Loffredi, Eric Seedorff, Mary Poulton

"The New Face of Mining is a recognition of the central role of human beings in mining and the underappreciated power they can have in generating breakthroughs in business performance and shareholder value. The key is people creating, aligning on, and subsequently enacting the future of mining. A methodology that is effective creates a corporate environment for alignment to be possible and then transforms operations by embedding the necessary behaviors, processes and practices. The people within the organization then are empowered to find and to implement solutions quickly, as measured business results demonstrate in case histories of diverse mining challenges around the globe and over the decades.Urgent case for actionThe physics of mining does not change fundamentally over time, but the context in which it operates changes rapidly, periodically requiring a new face of mining. “The New Face of Mining,” which has been used as a metaphor for the campus-wide mineral resources research organization at the University of Arizona, has many facets, including societal, generational, technological, financial and environmental, but at the center, always, is humanity. The New Face of Mining is not necessarily about age, it is about people first imagining and then creating a new future for mining. The challenges facing the global industry evolve from year to year and differ in individual companies or mines at any one time.Quantified outcomes from case studies indicate that a methodology, now also offered annually in a four-day, open-enrollment leadership program tailored to the mining industry, is effective at generating breakthrough results in the mining business. Such challenges range from those with important technical components to others that are mostly social challenges. Our focus, however, is the centrality of people in aligning on and enacting the future of mining. We use the phrase New Face of Mining for leadership and ways to empower people in organizations that commonly are overlooked in the mining industry. Some of the material in this article is based on the ideas of Werner Erhard and on the book by Steve Zaffron and Dave Logan (2009), The Three Laws of Performance: Rewriting the Future of Your Organization and Your Life.At Davos, Switzerland in January 1992, nine visionary mining chief executive officers (CEO) gathered to create the Global Mining Initiative. Much has changed in the 26 years since that meeting:• The world GDP has increased from US$25.4 trillion to $75.8 trillion.• The annual number of U.S. patent applications increased from 186,000 to 629,000.• The number of websites has increased from 100 to 1 billion.• The number of academic references to artificial intelligence has climbed from more than 16,000 to more than 1 million.• The number of cell phone subscribers grew from 11 million in the United States to four billion globally."

Oct 1, 2019

By A Gray

Physical separation features in almost every mineral processing circuit. The category encompasses a broad range of techniques and technologies including hydrocyclones, gravity concentration methods (including jigs, spirals, centrifugal concentrators, tables, heavy media separators) and thickeners, all of which make use of the inherent density differences between two mediums. It is also possible to include flotation, magnetic separation, and ore sorting in the physical separation category.However, opportunities for enhanced physical separation performance can now go beyond the common practice of optimising unit operations. Improved options exist for feed preparation ahead of the physical separation stage, enabling higher performance and lower cost outcomes for physical separation flow sheets and technologies.The use of new applications in breakage technologies combined with mineral liberation analysis to optimise liberation prior to the physical separation stage provides options for preconcentration and gangue rejection as well as better separation efficiency. The use of low cost gangue rejection and preconcentration can be an intermediate step between mining and processing that allows processing of lower cut-off grades from the mine whilst delivering higher grades to the mill.Optimising flow sheets and technology performance requires detailed understanding of particle size and shape distributions as well as liberation characteristics to suit the particular separation unit, combined with knowledge of the available technologies, their capabilities and the economic impact across the whole mine cycle.CITATION:Gray, A, 2017. The role of liberation in physical separation techniques, in Proceedings MetPlant 2017, pp 147–156 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 11, 2017

By R. D. Brown

"AbstractIn order to raise the enormous amounts of capital which will be essential for the development of Canada's mineral and petroleum resources, this country's resource industry must be permitted to earn an acceptable rate of return. The existing tax regime, with its high rates, complexities and misdirected incentives, presents a serious obstacle to our resource industries in their development of Canada's immense , but increasingly lean, resources. Government tax and other policies are not the only cause of the crisis now facing the resource sector in Canada, but a reformed tax system, with stable and reasonable tax burdens, is required if Canada's resources of minerals, oil and natural gas are to continue to contribute in the future, as in the past, to our national well-being.An independent task force, organized under the auspices of the Canada West Foundation, has recently completed a wide -ranging report: on the future development of Canada's mineral, oil and gas resources. This five-volume report, completed after almost two years of research and study, concludes that Canada •is facing a major crisis •in the development of our resources, It states that unless corrective action is taken now, mineral production and exports could decline drastically after 1985, at the same time that Canada would face massive bills for imported oil because of inadequate and declining production.The task force, chaired by the author of this article, has put forward recommendations for a fundamental shift in both federal and provincial policies in order that Canada's mineral reserves can be developed in the national interest. This article consists of excerpts from the summary of the task force's report."

Jan 1, 1977

By Donald W. Trepp

Colony Development Operation is a joint venture currently consisting of four active members; The Oil Shale Corporation (TOSCO); Ashland Oil Inc.; Shell Oil Company and Atlantic Richfield Company, operator of the project. The initial efforts on the Colony project began in the spring of 1965. Pilot mining and semi-works engineering programs continued, in phases, to completion in the fall of 1972 when commercialization of oil shale was deemed realistic. Since that time, Colony efforts have been directed toward evaluation of the data collected during the semi-works operation and in designing a commercial operation. In October of 1974, Colony announced: "because of economic and national energy policy uncertainties it was suspending plans to start construction of a commercial oil shale plant on private lands in northwestern Colorado, scheduled for spring of 1975."

Jan 1, 1975

By T. P. Meloy

Understanding the illusive nature of the catastrophic failure of brittle solids is difficult. Proposed is a hypothesis of crack cessation. If, during catastrophic failure, cracks in a brittle solid stop before terminating on a preexisting crack, this hypothesis suggests that the slope of the size distribution curve will be lower. Moreover, this hypothesis suggests that when cracks stop, negative valleys and negative comers appear. Furthermore, particle shapes also change with particle size. While the hypothesis is unverified, it suggests that crack cessation could play a role in the comminution process.

Jan 1, 1996

By David B. Dreisinger

Mass and heat balance modeling is a powerful tool for the design and analysis of hydrometallurgical process flowsheets. In this first of two papers, we examine the basic fundamentals of mass and heat balance modeling, and apply these concepts to several flowsheets using a simple spreadsheet model. In this way, we aim to demonstrate how such models are not only easy to construct, but can also be indispensable for comparing various flowsheet alternatives, for making rational economic decisions, and for developing a basic understanding of existing process behaviour.

Jan 1, 2002

By W. Kempson

"As has been noted on numerous occasions, the vertical shafts being sunk around the world are all tending to get deeper as we seek to take advantage of higher grades of minerals which can sometimes be found at greater depths. One of the challenges with these deeper shafts is the requirement to supply services to the mine’s operations at depth as well as the requirement to dewater the mine. Both the supply of water and the dewatering of mines is generally done using piping. With the greater shaft depths, this piping is now required to contain higher pressures as well as to accommodate changes in temperature resulting from normal mine operations. This paper will discuss the requirements for the design of high pressure piping in deep vertical shafts. The discussion will start with the general definition of the systems and the detailed design requirement. Once this is clearly outlined, we will discuss the options available for fulfilling these requirement as well as the advantages and disadvantages of each of the systems. We will finish with the installation recommendations and provide a basis for the maintenance of these systems. INTRODUCTION Piping in vertical shafts is used to provide a number of services in underground workings. These services vary depending on geographical location and the type of the ore body which is being mined. For example, in the Zambian Copper mines, one of the largest requirements for in shaft piping is for dewatering. Similarly in the Gold deposits in the West Wits basin as well as the deep level Copper deposits in Arizona, one of the largest uses for the piping is the supply of a cooling medium to underground workings to create a safe working environment (this can in the form of water or of glycol depending on the application). In South Africa, systems were installed which used the hydrostatic head which is generated from supplying chilled water to mines whose depths exceeded 2,000 m below surface. This chilled water was supplied as a closed system, allowing for high pressures to be generated which was then used to supply useful work (for example, Rock Drills, Face Cleaning and other ancillary services) whose power was traditionally supplied by compressed air or electricity. This system was initially researched by Chamber of Mine in South Africa. The design pressure range of these systems is 14 MPa to 18 MPa."

Jan 1, 2019

By Ph. D. Favreau, Favreau Patrice B. Eng, R. F.

Geology is important in mining by helping to identify the rocks which contain sufficient valuable ore to justify their excavation. Geologists give a geological name to each rock type, so geology is a player in blasting; when a blaster has successfully blasted rock of a given geological name at a former site, and he later has to blast rock at another site whose rock has the same geological name, then his first trial often is the same method as he used at the former site, since the geological name of the rock is the same

Jan 1, 2019

The paper describes data from test work programs on a range of magnetite ores in Australia and overseas. The analysis looks at the behaviour of material of different sizes fed to the rolls and the change in product size as a result of that, the conclusion being that there is a logarithmic relationship. The paper develops a form of equation to predict the product size from a given feed size distribution. The behaviour of the various magnetite ores is compared to more standard test methods such as crushing work index and unconfined compressive strength.

Jan 1, 2009