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By J. P. Harrison, J. A. Hudson

ABSTRACT: Given the current widespread use of numerical models for rock mechanics and rock engineering, and the ‘Technology Road Map’ theme of the Congress, it is timely to consider the key issues in matching numerical models to rock engineering problems. The three main aspects are: a) identifying the mechanisms, variables and parameters that are relevant to a particular rock engineering project; b) establishing the content and mode of operation of a particular code; and c) deciding whether a particular code provides an adequate model for a particular project. We summarise the key issues, highlighting the concept of rock mass domains, validation and the ability to present the results of a modelling exercise. We include three compact numerical modelling case examples to illustrate the points. Finally, we also present a ‘roadmap’ to assist in the process of matching a numerical model to the rock reality. RESUME: Considérant l’utilisation généralisée des modèles numériques en mécanique des roches et en ingénierie au rocher ainsi que le thème du congrès ‘technology road map’, il est opportun d’aborder les problèmes essentiels liés au choix des modèles numériques dans les problèmes ingénierie au rocher. Les trois aspects principaux sont : a) l’identification des mécanismes, variables et paramètres appropriés au projet considéré, b) la définition du contenu et du mode de fonctionnement d’un code numérique donné, et c) la possibilité de décider si un code donné fourni un modèle approprié au projet considéré. Les points clés sont résumés en mettant en évidence les notions de “massif rocheux”, de validation et de capacité à présenter les résultats d’une approche numérique. Nous présentons trois brèves études de cas qui illustrent ces points. Enfin, nous proposons aussi un logigramme pour aider au choix d’un modèle numérique approprié pour représenter la réalité d’un problème au rocher. ZUSAMMENFASSUNG: Im Licht der augenblicklich weitverbreiteten Nutzung von numerischen Modellen in der Felsmechanik and im Felsingenieurbau und unter Beruecksichtigung der Themenstellung des Congresses “Technology Road Map”, erscheint es an der Zeit die Kernprobleme, die sich mit Fragen der Abstimmung der numerischen Modele mit Hinblick auf ihre Anwendbarkeit im Felsingenieurbau beschaeftigen, naeher zu befassen. Die drei wesentlichen Aspekte sind: a) Identifizierung der Mechanismen, Variablen und Parameter, die fuer ein bestimmtes Projekt im Felsingenieurbau von Bedeutung sind; b) die Festlegung des Inhalts und des Modus Operandi eines bestimmten Codes, und c) die Entscheidung darueber ob ein bestimmter Code ein hinreichendes Model fuer ein bestimmtes Projekt ergibt. Wir fassen die wichtigsten Punkte zusammen, heben dabei das Concept der Gesteinsmassen Domaenen (Rock mass domains) hervor, und erarbeiten ihre Beurteilung und die Moeglichkeit diese zu praesentieren in den Ergebnissen einer Model Uebung. Wir schliessen drei Beispiele von numerischen Modellen ein in denen diese Punkte erlauetert werden. Zuletzt schlagen wir eine “Roadmap” vor, um dem Prozess der Abstimmung des numerischen Modells mit der “Felsmechanischen Wirklichkeit” zu unterstuetzen.

Jan 1, 2003

By J. M. Menacho

As usually occurs in technological development, heap leaching knowledge has been built upon two parallel lanes, theory developed on fundamentals but relatively far from industrial applications, and operational know-how generated from empirical trial and error. As a contribution to close the gap between the above-mentioned lanes, the De Re Metallica process consulting group has been developing and applying fundamentalsbased modeling tools for industrial process design and process optimization of existing plants over the last ten years. As result, a library of models is now available with application to the whole production chain from blasting to electro winning. This presentation is centered in heap leaching and several real case studies are developed, showing how paradigms are broken when fundamentals are applied. Cu2007 - Volume IV (Book 1) The John E. Dutrizac International Symposium on Copper Hydrometallurgy Edited by P.A. Riveros, D.G. Dixon, D.B. Dreisinger, M.J. Collins Toronto, Canada,

Jan 1, 2007

By Mauricio Monteiro Machado, Neyda de la Caridad Om Tapanes, Ana Isabel de Carvalho Santana, Rodolfo Salazar Perez, Rodrigo Ribeiro Soares, Roberta Gaidzinski

Vasos de pressão são equipamentos empregados nas mais variadas indústrias, sendo responsáveis por significativa parcela do orçamento. Os materiais mais utilizados para a construção de vasos de pressão para a indústria de óleo e gás são as ligas de aço carbono e em alguns casos se justifica o emprego de ligas de aços inoxidáveis. O objetivo deste trabalho foi estudar as características dos vasos de pressão, materiais de fabricação e o custo de aquisição de vasos de pressão por parte da Petrobras. Para o desenvolvimento foram utilizadas duas ferramentas de processamento de dados: a Lei de acesso à informação que permitiu a criação de uma base de dados, e o Planejamento de experimentos que possibilitou avaliar a influência do tipo de material e outras variáveis sobre o preço do vaso de pressão (variável de resposta). Os resultados estatísticos demonstram que, para as faixas analisadas o comprimento entre tangentes (CET) e o Diâmetro (D) possuem uma influência estatística direta sobre a variável de resposta Preço. Finalizando, o estudo conseguiu conciliar aspectos construtivos com os fatores financeiros, sendo de grande valia para os fabricantes de vasos de pressão.

Aug 1, 2019

By R. K. Young

This paper describes a computer-based Data Acquisition System which provides efficient data logging and retrieval, control of on-line gas chromatographs, and instantaneous calculation of material and energy balances.

Jan 1, 1977

By Tokio Yanagida

Major parameters relating to the operating of the conventional calcine-charged reverberatory f'ce process such as distribution coefficients of major elements among slag, matte, blister, and gases, temperatures and weights of intermediates, and heat losses of furnaces were measured and determined. A computer program to estimate heat and material balances at the process was prepared utilizing these data, showing a good agreement with actual results.

Jan 1, 1984

By G. L. du Plessis

This paper describes the design, installation and operation of an endless rope haulage system recently built for and commissioned at Evander Gold Mines in Mpumalanga, South Africa. The factors which lead to the choice of such a system and the advantages gained over more commonly used winding systems are outlined.

Sep 1, 2001

For processing plant design it is essential to develop a consistent material and (usually) energy balance as a basis for equipment sizing. This paper discusses techniques for consistent material balance generation, from hand calculation, through spreadsheets to specialised computer programs and general purpose simulations. The appropriate matching of techniques to problem complexity is considered, as are some possible trends for the future.

Jan 1, 1991

By G. W. Cutting

Interlocking material balances on complex mineral dressing plants greatly assist in metallurgical investigations: indeed, without such a balance, there is no firm basis upon which to base process performance evaluations. To achieve balances both qualitative and quantitative data must be rationalised in conjunction with the process flowsheet. WSL has developed a range of programs to evaluate interlocking material balances. However, to obtain maximum benefit from the balances, answers of direct value at the process level must be provided: WSL has developed also a range of programs for this purpose. Practical examples are given, which illustrate the benefits obtained from process balances.

Jan 1, 1979

By K. Turgeon, D. Larivière, L. Whitty-Léveillé, J. -F. Boulanger, C. Bazin

"The processing of ore containing rare earth elements leads to the production of an impure solution of these elements. The separation of the rare earths from the impurities and the production of individual elements is usually carried out by solvent extraction. The effectiveness of the extraction conditions and of the reagents is generally tested in the laboratory. This paper deals with the processing of results from solvent extraction laboratory tests planned to generate data redundancy. A method is proposed to take advantage of the data redundancy by accounting for the pH variation during the extraction. The parallel processing of several tests also allows estimating the equilibrium constants for the extraction. The proposed method produces equilibrium constants that are more reproducible than values estimated using conventional approaches. The method is illustrated with solvent extraction tests conducted on synthetic solutions of rare earth elements.INTRODUCTIONThe processing of ores containing rare earth elements (REE) usually includes the production of a concentrate of the minerals carrying the REE. These minerals, for instance monazite and bastnäsite, contain the 14 elements from La to Lu plus yttrium and scandium. As an example monazite has the general formula of (La,Ce,Pr,Nd,Sm,Eu,Gd,Tb,Dy…Lu)PO4 with a typical lanthanum content of 20-26%, cerium content of 40-50%, praseodymium of 4-6%, neodymium of 16 to 20%, and decreasing concentrations of heavier elements (Gupta & Krishnamurthy, 2005). During the processing of a REE mineral, it is generally not possible to isolate and separate a single REE from all the rest. The mineral molecules need to be broken (usually via a heat treatment followed by leaching with a base and/or an acid) to produce an aqueous solution of the REE of the ore. After purification of the solution, the REE can be precipitated as a bulk concentrate and sold to a refinery that separates the REE into particular groups of REE such as the light versus heavy REE or into individual elements such as lanthanum, neodymium, or europium oxides to yield value-added products."

Jan 1, 2016

By Claude Bazin

"The On-Stream Analyzer has proven and is still proving to be an extremely valuable tool for the control of flotation circuits. This paper examines the possibility of going further in the utilization of the provided assays using a real-time material balance program to calculate the distribution of solids within the streams of a circuit. Mass balance results can be used for process control, process analysis and detection of sensors malfunction. Examples from 3 Canadian and one American concentrators are presented to illustrate the potential of the method.IntroductionThe On-Stream Analyzer (OSA) has gained, over the last two decades, the status of key instrument for the control of flotation plants. The OSA is currently used in almost every sulphide flotation plant and its application in oxide mineral flotation plants is increasing. On-Stream Analyzers provide X-rays pulse counts that are converted into assays using multilinear regression programs. The estimated assays are passed to the flotation operators, via an operator console, or to control loops of various degrees of complexity (McKee, 1991) implemented in a Distributed Control System (DCS). Operators and/or controllers take control actions based on these assays to ensure an adequate operation of the plant. Although this application pays off very rapidly for the purchase of the OSA, one should ask: Could we get more from the OSA?Some plants reported the use of OSA measurements to process optimization (McKee, 1991). The optimization strategy is based upon economic indices calculated from metal recovery using the 2 product formulae (Wills, 1992, page 124). The 2 product formulae is however sensitive to measurement errors in the assays and can lead to considerable scatter in the calculated indices (Hodouin et al., 1993). Least squares algorithms provide an interesting alternative to filter out measurement errors (Spring, 1992). This paper presents a recursive least squares algorithm that estimates in a real time fashion the mass flow rates in a flotation plant using OSA and mass flow measurements. The algorithm is robust and its recursive structure is not demanding in terms of computation time and memory. The method was tested with data from four concentrators. Results of the material balance algorithm prove to be useful to detect sensors malfunction and may potentially be used for the control and optimization of flotation plants.The paper is divided into two sections. The first section gives a description of the proposed method. The mathematics of the method are kept to a minimum, since the detail is presented elsewhere (Bazin and Franklin, 1994). The second section shows the application of the method to different flotation plants."

Jan 1, 1995

By J. K. Mitchell

Soil improvement is examined within the context of the characteristics of different soil types, the types of ground improvement techniques that can be used to improve them, and the level of improvements that might be achieved. Several case histories are described to show how the particular soil and foundation characteristics influence the choice and success of different ground improvement techniques. Although the basic methods for soil improvement have been known for many centuries, there have been significant recent advances in the technology for their use. Time effects following the densification of cohesionless soils may lead to significant improvements in strength and stiffness. Unanticipated chemical reactions may follow stabilization using admixtures when soils for which there has been little prior experience are encountered. In some cases foundations that combine features of both ground improvement and deep foundation systems may provide good performance at reasonable cost.

Jan 1, 2010

By R. J. Lutton

The suitability of large-stone materials continues to present occasional problems in US construction. Distinctive modes of rock deterioration cracking, spalling, delaminating. disaggregating, disintegrating, and dissolving help to distinguish causes of deterioration. Design requirements, costs, and environmental factors remain critical to performance. The rating of material quality from superior hypes such as granite to marginal types such as conglomerate is too simplistic but may be useful in a preliminary way. Regardless, the market is dominated by limestone/dolomite material types because of their widespread availability. Certain tests that have been standardized are widely accepted and used for evaluating stone as riprap and armor. These tests are adapted from those used extensively for concrete aggregate; they explore the resistance of the rock to destructive processes such as abrasion, freeze-thaw, and wet-dry environmental attack. The field evaluation of the rock source is often as important as testing. Important limitations imposed by natural jointing and variations of bedding are documented in this manner. The field examination also supports the testing by estimating how much of the quarry is rep¬resented by each of the samples to be tested. Finally, quarrying and processing methods and transportation are carefully considered in regard to stone quality, average size, size gradation, and cost.

Jan 1, 1990

By A. M. Venter, C. W. Siyasiya, N. K. K. Arthur, M. G. Willemse, D. Marais

Although additive manufacturing is fast gaining traction in the industrial world as a reputable manufacturing technique to complement traditional mechanical machining, it still has problems such as porosity and residual stresses in components that give rise to cracking, distortion, and delamination, which are important issues to resolve in structural load-bearing applications. This research project focused on the characterization of the evolution of residual stresses in Ti-6Al-4V extra-low interstitial (ELI) additive-manufactured test samples. Four square thin-walled tubular samples were deposited on the same baseplate, using the direct energy deposition laser printing process, to different build heights. The residual stresses were analysed in the as-printed condition by the neutron diffraction technique and correlated to qualitative predictions obtained using the ANSYS software suite. Good qualitative agreement between the stress measurements and predictions were observed. Both approaches revealed the existence of large tensile stresses along the laser track direction at the sections that were built last, i.e., centre of the top layers of the samples. This in addition leads to large tensile stresses at the outer edges (corners) which would have the effect of separating the samples from the baseplate should the stresses exceed the yield strength of the material. Such extreme conditions did not occur in this study, but the stresses did lead to significant distortion of the baseplate. In general, the microstructures and spatial elemental mapping revealed a strong correlation between the macro-segregation of elemental V and the distribution of the β-phase in the printed parts.

Feb 6, 2023

By C. Holmes, T. Holmes

Engineered-in material handling problems are responsible for significant unrealized value in mineral processing plants. At the root, is a lack of awareness and understanding of bulk material handling science and how important it is, especially in early design stages. Mineral processes add value to mined raw feedstock through physical and chemical transformations in unit operations, but only if the material can flow through them. Essentially, each unit operation receives a unique feedstock and produces a unique product to be collected, transported, and fed into the next unit operation. Such material-handling systems can only be expected to achieve design throughput if the system equipment is designed to the materials’ characteristics, over their full range of conditions. This requires quantification of flow properties to support the necessary customized equipment designs. Too often, assumptions or “library values” of a material’s properties are used as the basis for flow modelling and conceptual, and sometimes even detailed, design. This is especially true for hazardous materials like uranium ore, for which the additional precautions, costs, and time necessary for safe handling are often used to rationalize postponing or even bypassing testing. The surprises that often transpire in the wake of insufficient material handling consideration can have acute and costly effects. Fortunately, there is a better way.

Jan 1, 2020

By G. Roderick Eggert

Material criticality reflects the degree to which a raw material is both necessary and subject to supply-chain risks. This study compares the criticality of selected raw materials from the differing perspectives of the manufacturing sectors of China, the European Union, Japan and the United States.

By M. S. Shishvan, J. R. van Duijvenbode, L. M. Cloete, M. W. N. Buxton

Geochemical and mineralogical datasets from Tropicana Gold Mine, Australia, have been used to define ore fingerprints. VNIR/SWIR spectral data were represented by four normalised wavelength regions and were clustered to form spectral classes. Sequentially, these spectral class proportions within a block and collocated XRF data were clustered to form material types (fingerprints). The material types were related to an Equotip-BWi correlation. These correlations can be used to extrapolate a hardness signature and generate a BWi proxy for different blocks. The combined fingerprints and BWi proxy can assist as a tool for enhancing the prediction of comminution behaviour. They can explain specific domain-related hardness variations. For example, one material type could be separated into a softer (~15-18 kWh/t), and harder (>20 kWh/t) material blend. This was accomplished using the commonly overlooked VNIR region at 605 nm. This outcome has significance for blending strategies.

Sep 1, 2021

By Schonert K

The throughput of a HP-roller mill is determined by the acceleration of the feed material within acceleration zone and introduction into the compression zone. Both processes depend on the internal friction and the friction of the material on the roller surface which is influenced by the surface structure and adhering of material. The particle motion in the acceleration zone has been investigated with high speed videos showing the effect of the centrifugal force and the slip on the roller surface. The throughput is discussed in the term of the specific throughput which can be approximated by a linear function characterised by the throughput number and the throughput elasticity. The throughput number is a helpful measure for investigating the influence of the feed material and the surface structure. The experimental results give some guidance for chosing an optimum corrugation profile.

Jan 1, 1993

By R. L. Grayson, T. L. Dickinson, C. G. Anderson

Sponsored by the EPA, USGS, DOE, and NSF through the Committee on Earth Resources, the National Research Council’s Committee on Material Flows Accounting of Natural Resources, Products, and Residuals, created in August 2002, studied the value that material flows accounting, which can track the flow of a material from the time it is extracted to its ultimate disposal, may provide for making better integrated economic, social, and environmental policy decisions. This could be a crucial technology for the mining industry to incorporate. This paper will recount the statement of tasks, the study process, and the science-based conclusions and recommendations reached.

Jan 1, 2004

By T. Donkin, B. Patterson, M. I. Guthrie, J. T. Ross

"Interest in the use of particle-based ore sorting has increased significantly with recent advances in sorting technologies and higher capacities per unit. Particle-based ore sorting has the potential to provide great value in processing lower grade ores from mines while delivering higher grades to the mill, as well as in upgrading waste rock into ore. Typically the focus is on the amenability of the ore to ore sorting and associated reductions in energy, water, and consumables utilization. However, layout significantly affects the installed cost of a processing plant, and the impacts on layout from fitting an ore sorting circuit into the plant plan need to be carefully considered. This paper examines processing plant layout considerations that play an important role in ore sorting projects, including additional crushing and screening requirements, transport of rejected material back to the waste stockpile (mine fleet requirements), and effects on the processing plant footprint. ¦ KEYWORDS Cold climates, Ore sorting, Plant layout RÉSUMÉ L’intérêt porté à l’utilisation du tri granulométrique du minerai a considérablement augmenté au vu des récents progrès réalisés en matière de technologies de triage et des capacités supérieures par unité. Le tri granulométrique du minerai offre une plus-value intéressante en termes de traitement du minerai à plus faible teneur extrait des mines ; il permet par ailleurs l’acheminement vers le concentrateur de minerai à plus haute teneur et la revalorisation des stériles dans le minerai. On met généralement l’accent sur la susceptibilité du minerai au triage et sur les réductions connexes en termes d’utilisation de l’énergie, de l’eau et de biens consommables. Cependant, l’aménagement physique de l’équipement a une incidence non négligeable sur le coût installé d’une usine de concentration, et les répercussions sur l’aménagement de l’installation d’un circuit de triage du minerai dans l’usine doivent être soigneusement examinées. Cet article étudie les considérations relatives à l’aménagement de l’usine de traitement qui jouent un rôle important dans les projets de triage du minerai, et notamment les exigences supplémentaires en matière de concassage et de criblage, le transport de matériau résiduel jusqu’à la pile de stockage des déchets miniers (nombre de camions requis dans le parc minier) et les effets sur l’empreinte de l’usine de traitement. ¦ MOTS CLÉS aménagement de l’usine, climats froids, triage du mineraiINTRODUCTION Ore sorting has been practised throughout history. An early report by Agricola in 1556 documents how metallic and non-metallic minerals were extracted from rocks by laboriously breaking them with hammers and picks and hand-picking selected material with higher grade (Hoover & Hoover, 1950). The concept has not changed, but sorting technology has evolved significantly over the last 20 years"

Jan 1, 2019

By E. V. Bowman

This paper is intended to deal with the material handling aspects of fine coal cleaning as applied to a recently built plaint in: southern West Virginia. This plant is processing 160 tons per hour of 1/4" x.0 coal on a two shift basis. Past experience with this very friable low volatile metallurgical coal indicated that its plastometer readings, varied directly with the size and length of time elapsing between mining' and ultimate consumption. Due to the mines location with, respect to its consumers, little could be done to decrease the time element. Studies indicated that the plastometer readings are considerably less in the minus 60 mesh range than that experienced in the plus 60 mesh sizes. Therefore, handling the coal in such a manner as to have the least amount of degradation became extremely important.

Jan 1, 1961