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By Andrew T. McBride, Malcolm S. Powell, Indresan Govender

"Current empirical Semi Autogneous Grinding (SAG) mill models contain assumptions concerning the amount of energy available for particle breakage, how this energy is distributed in the mill media and the rate at which the energy is transferred. Despite these assumptions the JK SAG model is highly functional with a proven track record. DEM provides a numerical framework to greatly improve on these assumptions that were necessary due to a lack of available input data.This paper identifies key outputs of the Discrete Element Method (DEM), such as energy spectra and impact probability distribution. It describes how they can be incorporated into current mill models utilising practical rock breakage data. The rate at which energy is transferred is shown to be dependent on particle position and mill rotational speed and not once per cycle as previously assumed. Based upon this an improved energy transfer methodology is presented. The fundamental outputs of the DEM are validated against experimental three-dimensional particle tracking data, so as to establish whether the DEM produces correct energy transfer predictions on the inter-particle level, which is crucial to this work."

Jan 1, 2003

By Aziza A. Yousef, Suzan S. Ibrahim, Mahmoud A. Arafa, Mohamed A. Abdel Khalek

In view of the shortage of soft water all over the Middle East countries, seawater may be used to replace the fresh water in flotation beneficiation. The flotation process required about 7 m3 of fresh water/ ton ore. This article aimed to study the effect of seawater cations and anions on the flotation process of four important mineral commodities. The adsorption of collector, zeta-potential, zero point of charge and floatability of pure minerals were studied. The individual effects of different cations and anions that are predominant in seawater, within their more or less actual concentrations were studied on individual mineral and on groups of them. The troublesome Ca2+ and Mg2+ ions, in the anionic circuit could be controlled by soda ash addition to the pulp before the anionic collector. The addition of sodium silicate improved the floatation selectivity of mineral mixtures and natural ore. At the optimum conditions the calcareous phosphate ore yielded a concentrate recovery of 83% with a grade of 34% P2O5, with 0.61%MgO, which from an ore assaying (25.3% P2O5 and 9.4% MgO).

Jan 1, 2003

By Stefaan J. R. Simons, Michael T. Spyridopoulos

In this paper the effect of humic substances (natural surfactants), electrolytes and solid particles on bubble coalescence, and as a consequence on froth stability, has been investigated. We formed two bubbles of equal size and forced them to collide using a novel experimental apparatus. The interactions were recorded by a high-speed camera, the images of which helped to determine the coalescence frequency and the coalescence time, as well as the mechanisms of the interactions. Two types of humic substances were used, along with three different electrolytes. Humic substances appeared to have a considerable effect on bubble coalescence, while the effect of electrolytes was minimal. Moderate and high hydrophobic glass spheres were used between two bubbles. Very hydrophobic spheres promoted fast bubble coalescence, while moderate hydrophobic spheres had no effect. We present data of coalescence frequency and time, as well as images of the coalescence events.

Jan 1, 2003

By Gus Van Weert, Samuel A. Bolorunduro, David B. Dreisinger

"Silver is currently lost as jarosite during the pressure oxidation of sulphides and cyanidation of the residues yields 5-10% of silver. Efforts to recover silver from complex sulphides, which contain economic fractions of silver require an understanding of the behaviour of acanthite during pressure oxidation. However, previous studies of acanthite (Ag2S) reaction have been complicated by the formation of argento-jarosite and uncertainties arise on the interpretation of the results.In this work, the acid pressure oxidation of high-grade natural silver sulphide mineral (acanthite) was carried out at 110-150°C and under the conditions similar to that of pressure oxidation of complex sulphide. The predominant product of reaction is elemental sulphur. The rate of reaction increases with increasing temperature and with the presence of ferric ions. The kinetics is controlled by chemical reaction with activation energy of 72.6 kJ/mol. The rate of reaction decreases with the presence of silver sulphate in the initial slurry. The proposed overall reaction is close to: []"

Jan 1, 2003

By Rainer M. Lotzien, Michael J. G. Battersby, Jan Kleefeld, Julian V. Brown, Rainer M. Imhof

"The standard method of separation using flotation is compromised in terms of kinetics and efficiency, because of the generally slow separating differentials of fine bubbles and fine particle suspensions. A new flotation system has been developed that addresses these issues and imparts other benefits. The new technology is based on established pneumatic flotation designs called Imhoflot which use intensive in-line pre-aeration to aerate the flotation pulp prior to its introduction to the separating cell. Consequently the cell is designed only for the separation of the phases and not for bubble-particle contact. In the new system this separation is speeded up dramatically by the introduction of centrifugal motivation in the separating vessel, without the use of internal moving parts. The design focuses on providing increased differential forces on buoyant mineralised bubbles and hydrophilic fines. The observed result of these differential forces is the improvement of concentrate qualities by the reduction of the amount of misplaced material found in the froth. The commercial benefit to industry is much reduced residence time, less than 30 seconds, which offers considerable cost savings in equipment and infrastructure.Prototypes of 0.65m, 1.7m and 2.2m cell diameter size have been constructed for hydrodynamic and industrial scale tests to assess the previously established computational methods for scale up of the process. The 1.7m cell has been installed and operated for cleaning of potash concentrates in Germany, at throughputs of 150 m3/hr, with extremely encouraging results. A 2.2m cell has been installed and operated in plant trials for superfine coal in South Africa. Results are presented that illustrate the effects of differential separations by comparison with conventional pneumatic and mechanical flotation techniques. Predictions of performance are provided in the contexts of the applications tested."

Jan 1, 2003

By A. Boulton

Low molecular weight synthetic polymers substituted with hydroxyl, carboxyl or sulfonate functional groups were used to improve the flotation separation of zinc or copper sulfide minerals from iron sulfide gangue minerals in three massive sulfide ores of different mineral composition. These polymers produced significant improvements in zinc or copper grades as a result of a selective depression of iron sulfide minerals. It was shown that this selectivity was the result of preferential adsorption of the polymer on the surface of the iron sulfide minerals. The different types of interaction between the functional group on the polymers and the sulfide mineral surfaces could explain the trends observed in the flotation results.

Jan 1, 2003

By T. A. Rickard

The notion prevails that writing is a knack, that the skilful use of the pen is a gift of nature. This is an error. Dogberry may be responsible for it; he said: "To be a well-informed man is the gift of fortune, but to write and read comes by nature". Because Dogberry said it, we may be sure that Shakespeare thought otherwise. Ability of any sort may be partly innate, but my own observation and experience lead me to conclude that most of the easy writers have become so by constant practice. As I recall the names of men successful with the pen, I remember that most of them have written a great deal and have taken particular pains to improve their style. The suggestion that proficiency in the difficult art is a happy accident provokes a sardonic smile. The larger part of the great writing in our literature is the result of persistent effort. An easy fluency has been the undoing of many; their flamboyant and fantastic scribbling has proved as perishable as froth. This criticism applies to technical writing also; in order that a technical description or discussion may hold the interest of the reader, at least long enough to cause him to read it to the end, the writing must be done carefully and systematically; otherwise it will fail in its purpose of conveying information. Clearness is absolutely essential. "It is not enough to use language that may be understood; it is necessary to use language that must be understood."* The purpose of writing, at least of that which is meant to be read by others, is not only to express ideas but to communicate them. Lack of perspicuity may prove as %ad as

Jan 1, 1931

By AIME AIME

Acid Open-Hearth Manipulation.. By ANDREW MCWILLIAM and WILLIAM H. HATFIELD, ii, 279. Discussion by J. J. MORGAN, iii, 647; E. H. SANITER, iii, 648; MCWILLIAM and HATFIELD, 111, 648. ADDICKS, LAWRENCE. The Effect of Impurities on the Electrical Conductivity of Copper, iii, 559. Address of Welcome to the U. S. National Museum, Washington, D. C. By RICHARD RATHBUN, .iv, 923. ALLDERDICE, TAYLOR. Discussion of MR. ROE'S paper, The Mann¬ facture and Characteristics of Wrought Iron, v, 1091. American Mining Engineer. Discussion by ARTHUR JARMAN, iii, 641. An Automatic Stock-Line Recorder for Iron Blast-Furnaces. By J. E. JOHNSON, JR., iii, 509. Anthracite-Washeries. By GEORGE W. HARRIS, vi, 1263.

Jan 1, 1907

By Clara Godoy, Álvaro Dapía, Paulo Couceiro, Pablo Segarra, José Ángel Sanchidrián, Juan Navarro

This paper applies geostatistical tools in Measure While Drilling (MWD) data to estimate the probability distribution of values in all the points of the studied domain in order to assess the continuity of rock classes between boreholes. The analyses carried out by Ghosh et al. (2018) and Navarro et al. (2019) have been used as starting point of this work to classify the geotechnical rock condition in four classes: solid rock, fractured rock, cave- in rock and cavity. From it, an application for the geotechnical rock condition of orebodies have been developed, aiming at characterizing the rock before the charging the holes to minimize unexpected rock conditions and to address issues associated with charging and blasting operations. Such problems are closely related with non-optimal rock fragmentation after blasting.

Feb 1, 2020

By DING TANG, JINGHE CHEN, Shuiping Zhong, CHEN KUANG

The Zijinshan gold-copper mine, in spite of the low-grade nature of the ore, has become one of the largest production-scale and most profitable non-ferrous metal mines in China. The successful application of hydrometallurgy as well as proper engineering design are the key factors for large-scale development of the Zijinshan gold-copper mine. In this contribution, the practical experience acquired in the development of the Zijinshan gold and copper mines is summarized. This covers most aspects of the production process including mining, beneficiation, ore stacking, heap (bio)leaching, carbon-in-leach, solvent extraction, electrowinning, wastewater and tailing treatments. The authors believe that this practical experience will not only help to promote the development of hydrometallurgy, but can also serve as a model for other gold and/or copper plants around the world.

Jun 3, 2020

By AIME AIME

T HE Mining Methods Committee held its initial meeting* on Tuesday afternoon, with F. W. Bradley in the chair and W. Y. Westervelt as vice- chairman. The first paper to be presented was "A Plea for a U. S. Court of Patent Appeals," for which Kenneth W. Greenawalt ably pleaded. The paper (which was published in full in last month's issue) is so carefully prepared that no synopsis can do it justice. It discusses the opposed views of some patent lawyers and other lawyers and members of the judiciary as, for example, Chief Justice Taft who is quoted as saying in 1921: "I think it is a great deal better to take a first class lawyer and a first-class judge and make him a good patent expert than it is to take a patent expert and try to make him a first-class lawyer and a good judge." Mr. Greenawalt argued the need for specialized scientific and engineering interest and understanding to enable a lawyer or judge to prepare or interpret patent specifications and decide the originality necessary for a valid invention. He proposed the special U. S. Court of Patent Appeals to also counteract the costly confusion and injustice now ruling where a patent may be declared valid in the courts of certain States and invalid by the courts of other States.

Jan 1, 1930

By Robert D. Longyear

IN MOST diamond core drilling the primary objective is the recovery of samples to be used for chemical analysis, physical tests, or visual inspection. Unless these samples are reliable and the information systematically recorded, the time and money spent in securing them are largely wasted. A properly taken diamond-drill sample is similar to a properly moiled channel sample but more accurate. No channel sample can be moiled in as even a groove as the smooth cylinder of material normally removed in diamond drilling. More important still, sampling by the diamond drill practically eliminates that personal equation which Jora1emon4 reference numbers apply to publications listed in the bibliography at the end of this article) has aptly termed "the almost magnetic attraction of the most conscientious hand toward rich pieces of ore."

Jan 1, 1937

By Christian Villalobos, Gilmer Engracio, Juan La Torraca

En junio del 2018, el minado de las fases profundas del Tajo Calaorco en la unidad minera La Arena, interceptó el nivel freático, lo cual no permitió continuar con el minado en dichas fases, poniendo en riesgo la extracción de 1600 onzas de oro, en el primer año, 800 onzas de oro para el segundo y tercer año respectivamente, y 500 onzas de oro para el último año, por lo que fue necesario realizar la revisión y actualización del estudio Hidrogeológico, el cual recomendaría la implementación de una batería de pozos profundos con el fin de desaguar el agua subterránea y así poder cumplir con el plan de minado establecido. Por esta razón era necesario contar con los pozos operativos a una utilización cercana al 100%.

Sep 30, 2022

By Barbara Rutter, Phillip Mulligan

This research investigates how changes in shock tunnel geometry affect the pressure versus time waveform. The Large Arena Test Simulator (LATS), which is composed of four different rectangular sections connected by three expansion sections, was used to determine how the changes in geometry affect the shock wave profile.

Feb 1, 2020

By Karl Kristian Bagger

A construção naval sofreu nos últimos 40 anos várias mudanças de acordo com os diferentes cenários econômicos. O Brasil neste setor chegou a ocupar o segundo lugar na produção mundial, foi fortemente afetado pela crise recente. Diante desta conjuntura as empresas tem que otimizar seus processos visando um aumento na produtividade para se manter competitivas. A atividade da construção naval é complexa, tem várias etapas que geram interferências que muitas vezes impossibilitam trabalhos em paralelo. As chapas de aço que constituem as partes principais da embarcação, as estruturais, devem passar por um tratamento de preparação da superfície que inclui a sua pintura e proteção anticorrosiva, este é um dos processos mais críticos. Esta etapa além de demandar serviços muito especializados há ainda um aspecto agravante o ambiente confinado, que expõe os operários executantes a condições ergonômicas desfavoráveis proporcionando um rendimento baixo afetando diretamente a produtividade do processo. Este estudo realizou uma analise do processo e propôs as alterações nas etapas de fabricação eliminando os problemas proporcionando melhores condições de trabalho dessa forma minimizando o impactos ergonômicos, proporcionando redução de custo e aumento da produtividade.

Oct 30, 2017

By Ana Paula Domingos Cardoso

A indústria automobilística é um dos maiores mercados para aços de aplicações de conformação criticas, exigindo contínuo desenvolvimento de novos materiais e tecnologias. Dentre estes, destaca-se o revestimento metálico (GA) que é composto por diferentes fases Fe-Zn com boas propriedades de aplicação, mas o seu comportamento em processos de conformação é sensível à fragilidade das fases intermetálicas, podendo resultar na fragmentação por powdering. A presença da fase ? na superfície é prejudicial à tribologia do revestimento, pois eleva o coeficiente de atrito, a ausência desta fase pode significar transformação excessiva e maior fragilidade do revestimento, reduzindo a resistência ao powdering. A aplicação de filmes de pós-tratamento de pré-fosfatização sobre o GA, com ganhos de conformação através da redução do coeficiente de atrito, tem sido desenvolvido pela ArcelorMittal. Este trabalho objetiva avaliar a tribologia e resistência ao powdering de diferentes condições de superfície do revestimento. A evolução do coeficiente de atrito é determinada por ensaios de desgaste, além de ensaios de powdering e análises metalográficas via MEV-EDS para avaliação do pós-tratamento.

Aug 7, 2018

By N. Rouse

Underground raises and slots are a vital part of underground blasting operations. Raises and slots are vertical shafts or openings used for ventilation, ore passes, or creating voids in stopes. In the author’s experience, raise and slot designs can vary significantly from operation to operation or even within a single operation, sometimes for reasons unknown. The results of the various designs can differ depending on drilling accuracy, geology, and the explosives used in the design. The purpose of this paper is to summarize the recommendations found in published literature on raise and slot design in one document, while incorporating some of the author’s own experience with optimizing raise and slot designs in underground operations. Some inspiration is also included from burn round designs; small versions of raises drilled horizontally in development blasting rounds. This document includes discussion points on drillhole diameter and depth, pattern design and relief requirements, explosive types and loading recommendations, and timing. Ultimately, this document can be useful to those looking to design a raise or slot blast for the first time or for those looking to improve on the results from the raise and slot blasts used at their operations.

Jan 1, 2024

By A. Vishwakarma, V. Himanshu, K. Dey

Underground mining is the most feasible method after extinction of shallow depth ore deposits. Longhole stoping method is the most technically advanced method for the faster excavation. In this method, the holes are drilled in the form of ring pattern and explosives are used for the rock breakage. During blasting, the explosive energy sometimes also breaks the non-ore material. The non-ore material gets included in the extracted ore and enhances the ore dilution. Few uncontrollable factors which affects the ore dilution are ore body characteristics, rock quality, insitu stress condition etc. Apart from uncontrollable factors, explosive energy and blast design also plays an immense role in ore dilution. In the blasting practice, the purpose is to effectively utilise the explosive energy for rock breakage. The optimum delay is required so that the blast holes attain adequate free face before the blasting. This paper deals with the optimisation of blast design parameters to reduce ore dilution in underground hard rock mining having narrow vein. The study was carried out using numerical simulation. The explicit dynamics based modeller of Ansys was used for this purpose. The parametric variations in the models were done to optimise the parameters. The burden has been optimised first by varying the width of the narrow vein. The blasts of a ring consisting of single hole were conducted in the model by varying the width of the narrow vein. The damage contour under different parametric variations were analysed. The experimental trial has been also carried out at Zawar Group of Mine, Rajasthan, India. The optimum parameter was decided based on the result of experimental trial and numerical simulation model. The output of the model shows that optimum burden for 3.5 m narrow vein width is 1.12 m and for 1.0 m, it is 1.54 m. This shows that the optimised burden is higher in the vein having lesser width as compared to the greater width. The presence of joints/changed media/interface (between the sidewall and narrow vein) is the major reason behind this. The wave gets reflected back very fast on coming in contact with joints in a 1.0 m narrow vein as compared to a 4.0 m narrow vein. This will quickly convert the compressive wave into tensile wave giving rise to tensile slabbing. Hence proper utilisation of explosive energy will take place for the breakage of rock mass when the width of the narrow vein is smaller. The burden obtained from the experimental trial and numerical simulation models is less than 2.0 %. Hence the numerical simulation based approach can be used for the assessment of the optimum burden for ring blasting in narrow vein under different geomining conditions. This helped in reducing ore dilution and maximization of ore recovery. In the future, empirical relationships may be developed by considering different geological discontinuity, the strength of the rock mass and explosive parameters.

Jan 1, 2024

By E. Lentilucci, A. Dey, X. Liu, A. Datta, S. Ghosh

The segmentation of quarry blast smoke plumes is a crucial research area that has the potential to enhance safety, environmental monitoring, object detection, and regulatory compliance in the mining industry. Smoke plume segmentation can be used to identify the spatial extent and temporal evolution of smoke plumes generated by the blast. This information can be used to improve the understanding of blast dynamics and optimize blast designs. Furthermore, smoke plume segmentation can assist in identifying potential environmental and health hazards associated with the release of smoke and dust particles into the atmosphere during quarry blasts. However, many current smoke plume segmentation algorithms are designed for segmentation of smoke plumes from fires and are not suitable for segmentation of plumes from quarry blasts. The proposed method in this paper leverages the video frame captured before the blast as a stationary background image, which helps to reduce other confuser objects present in the image along with a selfadaptive clustering method. The color channels of the image are utilized based on the different contrast properties of the smoke, with a self-adaptive gradient compensation applied for edge detection of the smoke plume. This approach offers a novel and effective way to segment smoke in quarry blast analysis, with potential applications in the calculation of noxious gas volume and concentration within the plume. Compared to other algorithms, our method improves accuracy, decreases the false alarm rates, and reduces the overall miss rate. Overall, this paper contributes to the research on smoke plume image segmentation, particularly for quarry blast smoke plumes, which possess unique characteristics that require specialized algorithms for accurate segmentation.

Jan 1, 2024

By Bernhard Hiebl

Global trends that are constantly challenging the iron and steel producers are related to worsening of the iron ore grades, higher substitution rates of main iron ores to cheaper raw materials due to economic pressure and increased environmental standards. Changing the raw materials in an operating plant can significantly influence the sintering or pelletizing process. Adjusting all process parameters to regain stable and high productive operation takes considerable time and causes production losses. Furthermore changes in raw materials lead to variations in the process gas flows and emission concentrations.Therefore SVAI developed two models for numerical simulation of sintering process and pelletizing process. Amongst others the models are based on Ergun equation and include chemical reactions of the related process. For already operating plants the simulations shall predict changes of the process parameters when raw materials are exchanged or when operational parameters are varied. Furthermore the simulations give advantageous information for the design of green field plants and allow the simulation of different plant configurations.The objective of this paper is to demonstrate what the latest developments are in these numerical simulations and what Siemens VAI is doing to overcome the remaining challenges in this field.

Aug 2, 2018