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By Olav Mellgren

Part I. The interaction between potassium ethyl xanthate and lead salts has been studied thermo-chemically. It is shown that ethyl xanthate reacts with lead carbonate, basic carbonate, thiosulfate and sulfate according to principles of simple chemistry, whereas reactions with lead sulfite, metasulfite, basic thiosulfate and hydroxide at high pH are associated with secondary reactions. A new compound "xanthogen thiosulfate" is postulated. Part 11. Adsorption of ethyl xanthate on galena has been studied quantitatively and thennochemi-cally. It is shown that an ion-exchange mechanism governs the adsorption process and that the heat of adsorption of xanthate on galena is equivalent to the heat of reaction of ethyl xanthate with bulk lead salts. It is concluded that the entropy content of the surface "compound" on galena is different from that of a corresponding bulk lead salt. Alkali depression is in part shown to be due to the instability of the xanthate-galena system at high pH and to the formation of basic lead salts. Sulfate and carbonate ions are shown to have a stabilizing effect on the xanthate-galena system. PARTI. THERMOCHEMISTRY OF ETHYL XANTHATE AND OF ITS REACTION WITH LEAD SALTS In the past little attention has been paid to the chemistry of lead xanthate. It is known that xan-thates form slightly soluble compounds with lead and that suspensions of lead xanthates in alkaline solution decompose rather readily.' The solubility of lead ethyl xanthate is of the order of 2.6 x 10-6 moles per 1. At increasing pH the xanthate concentration of a saturated solution contains more xanthate. Thus at pH 11 this xanthate content is about 100-fold larger than at pH 7.1 Xanthates are known to be consumed when added to a suspension of slightly soluble lead salts such as lead sulfate and lead carbonate. It is unknown to what extent this xanthate consumption is due to a simple chemical reaction because, frequently, observations are made which reveal secondary reaction products in such reactions. Thermochemical study of the reaction between xanthate and lead salts offers a means to clarify the significance of these reactions as the enthalpy changes can be accurately predicted from heat of formation of lead salts in pure solution reactions. In the present work the heats of formation of lead ethyl xanthate from potassium ethyl xanthate and lead salts are determined and some thermochemical aspects of xanthate in solution are studied. The results of these investigations are presented in Part I. In Part II the heat of adsorption of ethyl xanthate on galena surfaces is presented. All enthalpy changes were measured directly in a microcalorimeter. Calorimeter: The calorimeter used for measuring enthalpy changes was similar to that used by Redinha and Kitchener2 which was based on a description by Derbyshire and Marshall.3 Other useful references4,5 are listed. A sketch of the calorimeter

Jan 1, 1967

By C. Bazin, D. Hodouin

"A flexible model involving perfect mixers, stagnant zones, plug flow, material bypassing and recycling zones has been developed for interpreting mixing phenomena in mineral processes. The mixing properties are described by the residence time distributions which can be subsequently interpreted by the flexible model. User-friendly computer programs (for 1MB-PC or compatible) have been developed for simulation and modelling of RTDs using the proposed model. Seven mineral processing case studies are discussed in terms of experimental procedure, model calibration results and application of the estimated mixing model to process modelling, diagnosis, and performance evaluation. IntroductionIn any mineral processing plant there are continuous-flow machines that transform or separate the ore components. Grinding mills, flotation cells, conditioning and leaching tanks are examples of such machines. The performances of these vessels or reactors are controlled by the rate at which the reaction proceeds and the time spent in the environment where the reaction occurs. This paper deals with the latter aspect of mineral processes operation.Since most of the reactions occurring in mineral processing units are time dependent, knowledge of the residence time of the material in process vessels is important for modelling and diagnosis purposes. Due to the random mixing phenomena involved in the process equipment, there is a distribution of the residence time of the ore particles and the fluid in the vessel. The probability density function E(t) that a micro-element of the material flowing through a processing unit stays a time t in the vessel, is the residence time distribution (RTD) of the corresponding component."

Jan 1, 1988

By J. Kretschmann, N. Nguyen

"The Vietnamese economic growth of more than 5% per year leads this country to an enormous demand for raw materials. In the duration of ongoing expansion, the big challenge in the coming decades will be to make this process as sustainable as possible when it comes to economic, environmental and social objectives. Risk management especially in occupational safety and health (OSH) in enterprises is one of the most important tools to achieve this aim. But until now, this has not been taken into priority by Vietnamese coal mining enterprises. Main reasons for this situation can be found in deficient legislative conditions and in non-synchronized risk management systems. In contrast, Germany has implemented an adequate legal system and the German mining industry has gained lots of experiences in risk management, especially in occupational safety and health. This paper seeks to point out specific challenges how to improve occupational safety and health in Vietnam by transferring and applying German methods and standards."

Jan 1, 2011

A typical sub-level block cave mining extraction method employs an undercut level to establish a cavity in hard rock, and as such requires special support methods and products to be installed during the development phase. The undercut level development in the block cave orebody is then sacrificial, and support elements will eventually report to the crusher and perhaps conveyor belt systems for transportation to surface. The choice of support products installed in the undercut level development should take cognizance of the detrimental effect these could have on the mining system such as cutting of conveyor belts, obstructing crushers, safety aspects, and productivity. This work explores the probability and practicality of making use of new-generation support products to make the operation safer as well as enhance productivity in the development phase and during the undercut operation. This paper will investigate the use of glass reinforced plastic(GRP) rockbolts and GRP mesh instead of conventional steel bolts and mesh along with resin capsule-filled holes with the GRP bolts. Complementing this with thin spray liner (TSL) application as another means of creating a safer operating environment, as well as a productive support medium, will also be addressed. These proposed items are envisaged to reduce production downtime and improve the safety of our people. These items are all easy and light to handle, cuttable and crusher friendly, as they will break up during the crushing process.

Jan 1, 2012

By William A. Macaitis, Frank E. Dalton, Leo R. DiVita

The Metropolitan Water Reclamation District of Greater Chicago's Tunnel and Reservoir Plan (TARP) is a multi-purpose urban public works project with a total cost of $3.7 billion. Currently 51 miles of TARP tunnels are completed and operational and 34 miles are under construction. The excavated TARP tunnels have been constructed in rock utilizing 29 tunnel boring machines, ranging in size from 6.5 to 35.3 feet in diameter.

Jan 1, 1993

The HB 2500 hydraulic breaker attachment from Atlas Copco Construction Tools features Krupp percussion technology and a service weight of 2,500 kg (5,512 lbs). This makes it ideal for demolition, tunneling, trenching, foundation work, rock mining and secondary breaking. Suitable for carriers in the 29-to 43-t (32-to 47-st) weight class, the HB 2500 accepts maximum hydraulic flow of 219 L/min (58 gpm) at 18 MPa (2,610 psi) of pressure, and delivers an impact rate of up to 550 blows per minute. The HB 2500 features PowerAdapt, a new system that automatically shuts down the breaker in the event that it receives excessive oil pressure from the carrier.

Jan 1, 2006

By Meghan McGrath

Third generation advance high strength steels with microstructures of acicular ferrite and retained austenite were investigated and meet mechanical property goals. A good combination of strength and ductility were achieved with duplex ferrite and austenite microstructures where cementite formation was suppressed. Transformation induced plasticity (TRIP) behavior produced rapid work hardening. The mechanical properties of two hot-rolled steels with duplex microstructures were compared and had the following compositions: (1) Fe-0.14C-13.87Mn-1.42Si-3.51Al; and (2) Fe-0.06C-14.2Mn-1.85Si-2.38Al. These steels were cast, homogenized, and hot rolled at 900ºC to obtain a refined microstructure with ultimate tensile strengths and elongations to failure of 865 MPa and 39% and 1,217 MPa and 28%, respectively. The amount of metastable austenite in both compositions decreased after tensile testing from 58% and 28% to 6% and 0%, respectively. Microstructures were characterized using optical microscopy, scanning electron microscopy (SEM), and x-ray diffraction.

Jan 1, 2010

By Ivette E. Torres

Aruba, formerly a. part of the Netherlands Antilles, separated on January I, 1986, and became an autonomous part of the Netherlands. Full independence of the island from the Netherlands is scheduled for 1996. In this chapter, however, Aruba's statistics are included with those of the Netherlands Antilles. Tourism continued to be the main industry of the island, which continued to depend heavily on imports, mostly from the United States. During the year, the Government was preparing legislation to regulate the exploration of oil deposits in the relatively shallow sea around Aruba.

Jan 1, 1989

Mining ventures are essentially risky businesses. Explorers and project developers (plus their investors and financiers) attempt to minimise the risks involved or at least manage them. Core considerations are the obvious technical and commercial risks, but the socio-political system and regulatory environment in which the project will operate can be more important. Successful mineral investments in a country depend upon obtaining realistic and reliable technical results in a country that provides certainty, to gain and maintain investor confidence in a project. Brief commentary is provided on the usefulness of professional accreditation and ethics plus other specific reporting codes (eg JORC/VALMIN Codes) in reducing risks by reinforcing high technical competence and reputable individual professional behaviour (particularly in the context of currently perceived high corruption levels in so many countries). These various risk components are reviewed, especially in a global context, to showcase New ZealandÆs current position. Successful projects are those which provide investors with credible and reliable optimal results in less volatile environments because investors/lenders hate uncertainty and surprises even more.

Jan 1, 2005

By Staff

Introduction As the Sherritt Gordon property is still in the development stage, . it is rather difficult to write a proper account of the mining methods and milling practice that will be used. While the general scheme of operation will remain the same, there will undoubtedly be many minor changes to meet special conditions which we cannot forsee at the present time. Most of the work accomplished to date has followed the usual routine of preliminary development in the Canadian North. However, we have learned a few things which might be of use to others operating under similar conditions. The most important of these is the saving in power cost made possible by the use of Diesels as against steam power when using wood fuel, and the movement of freight by tractors when rail transportation is not available. Location The property i6 located about 90 miles north of The Pas, or 40 miles northeast of the Flin Flon mine. A branch line from Cranberry Portage, on the?C. N. railway, between Flin Flon and The Pas, connects the property with the outside.

Jan 1, 1930

By C. Gosselin, G. M. Payenzo, C. Bazin, M. Desnoyers, G. Chevalier

"ArcelorMittal Mines Canada operates hydraulic classifiers to reduce the silica content of an iron oxide concentrate from 4.5% to less than 1.2% SiO2. Sampling campaigns were conducted to develop a preliminary model for the hydraulic classifier. Results show that iron oxide and quartz are respectively concentrated in the coarse and fine size fractions of the classifier feed. The mineral partition curves in the classifier and the size distribution of the minerals in the feed are used to simulate the classifier operation in order to identify the source of variability observed in the daily plant production data. Results indicate that most of the variation is probably caused by unsteady operating conditions of the classifiers.INTRODUCTION Hydraulic classifiers are a class of gravity separation devices (Wills, 1992) used to classify particles according to their size and specific gravity. Hydraulic classifiers also known as density separators (Hearn, 2002) combine hindered settling and upward flow of water to selectively entrain light particles to an overflow stream. Denser particles settle to an underflow stream. Hydraulic classifiers are used for various purposes ranging from cleaning of coal (Das, Sarkar, & Mehrotra, 2009), recovery of chromite from plant tailings (Kumar, Tripathy, & Rao, 2009) to upgrading iron oxide concentrate (Hearn, 2002). ArcelorMittal Mines Canada operates several hydraulic classifiers to upgrade an iron oxide concentrate by removing fine quartz and other light minerals from hematite that is the main iron oxide mineral. A project was initiated to analyze the operation of the classifier in an attempt to identify the source of the variability in the production results and to assess the potential of increasing iron recovery in the classifier. One possible disturbance for the classifier operation is the change in the classifier feed composition and size distribution, while the other considered disturbance is the operation of the classifier. The paper is divided into five sections. The first section summarizes the ore processing sequence for the production of iron oxide pellets to identify the position of the hydraulic classifier in the process. The second section describes the hydraulic classifier. The third section discusses the sampling campaigns conducted on the hydraulic classifier. The method used to process the data from sampling, the results of the data processing and simulation of the classifier are discussed in the remaining sections."

Jan 1, 2012

By K. C. Ko, D. A. Pifer

The theory of probability with respect to the failure of structures is discussed. It is shown that the probability of safety, probability of failure, and factor of safety are directly related to each other and that as standard deviation approaches zero, the probability curves approach a unit step function which can be interpreted as the conventional factor of safety. The factor of safety is numerically the ratio of the load to the strength of the material at a particular point or plane in an engineering structure. Mathematically, it can be illustrated as a unit step function undefined at the point where the factor of safety is one (Fig. 1). The uncertainty of variation of soil and rock strengths require factors of safety much higher than those used in other engineering structures. The factors of safety used are generally determined from past experiences with similar structures. However, the factors thus determined do not have any theoretical meaning or do not indicate any relationship to actual safety.' It seems, therefore, logical to develop a system with a sound theoretical basis to obtain a more suitable factor of safety for structures. An application of elementary theory of probability indicates that it is possible to relate this number to theoretical and practical engineering facts.

Jan 1, 1971

This paper gives an overview of the difficulties associated with determining the strength of hard rock pillars. Although a number of pillar design tools are available, pillar collapses still occur. Recent examples of large scale pillar collapses in South Africa were caused by weak partings which traversed the pillars. Currently two different methods to determine the strength of pillars are used namely, empirical equations derived from the back analyses of failed and stable cases and numerical modelling tools with an appropriate failure criteria. Both techniques have their limitations and additional work is required to obtain a better understanding of pillar strength. Empirical methods are popular and easy to use, but care should be exercise that the results are not extrapolated beyond the range of the data which were used to derive them. An example is the Hedley and Grant formula (derived for the Canadian uranium mines) that has been used for many years in the South African platinum and chrome mines (albeit with some adaptation of the K-value) to design the pillar layouts. Very few collapses have nevertheless been reported and it might even be too conservative an assumption of pillar strength in these mines. As an alternative, some engineers strongly advocate the use of numerical techniques to determine pillar strength. A close examination unfortunately reveals that these techniques also rely on many flawed assumptions. An area where numerical modelling is invaluable, however, is to study specific pillar failure mechanisms, such as the influence of weak partings on pillar strength. In conclusion, it appears that neither empirical techniques nor numerical modelling currently provide a solid basis to conduct pillar design. It is therefore recommended that both these techniques be utilised when confronted with a pillar design to obtain the best possible insight into the problem.

Nov 25, 2010

This paper deals with the application of table flotation to two unusual mineral dressing problems. Both problems involved the removal of interfering minerals at sizes too coarse to normal froth flotation.The first problem was the removal of arsenical minerals from Broken Hill gravity concentrates without further size reduction. Table flotation without grinding of the original concentrates gave almost complete rejection of the arsenic from the concentrates. A typical test result was a reduction of arsenic in jig concentrate from 0.75% arsenic to 0.007% arsenic.The second problem was to develop a method to produce a high grade calcium carbonate concentrate from coastal dune sands containing about 10% silica and about 80% calcium carbonate. The sands were about 30 mesh British Standard Screen (B.S.S.), and for economic and other reasons it was stipulated that the separation be made without grinding. Again, table flotation gave excellent results. A concentrate was produced containing 99.62% acid soluble material, representing a recovery of 98.69% of the calcium carbonate in the feed with a rejection of 96.44% of the silica.The investigations' were carried out at the Kalgoorlie Metallurgical Laboratory, under the Department of Mines...

Jan 1, 1954

This paper describes a proposal to reopen the Sylvia gold mine for underground exploration and development for an initial production of 10 000 tpa. A combination of trackless mining equipment and railtrack would be utilised for development with ore extraction being carried out by undercut and fill methods. The use of the smallest LHD units for mucking, and rail track for the main haulage together with airleg drilling will form the basis for development and stoping. The proposal has been subjected to an environmental impact assessment report to evaluate the impacts of the proposal on the natural and social environment in the area.

Jan 1, 1987

By Richard C. Moore

The U.S. Bureau of Mines contracted a study to review the air and water monitoring requirements of five Federal environmental acts (the Federal Water Pollution Control Act, the Safe Drinking Water Act, the Clean Air Act, the Surface Mining Control and Reclamation Act, and the Resource Conservation and Recovery Act) and to compile information on the currently available monitoring instruments. A literature review of the acts and their associated regulations was conducted to determine applicability to the mining industry as well as any air and water monitoring requirements. In addition, an industry search and literature review was performed to assess the instrumentation available to comply with the monitoring regulations. Based on this research, the instruments are classified by general applicability to air, surface water, or ground water monitoring, then catalogued by monitoring parameters. A discussion is provided on recommended and innovative monitoring techniques.

Jan 1, 1981

By Daniel M. Flanagan

"Editor’s note: Each year, Mining Engineering features an industrial minerals review. Several people put in a fair amount of time in developing the material for this issue, all the while doing their own jobs. Thank you to the industrial minerals annual review editor, to the Industrial Minerals & Aggregates Division technical committee chair and vice chairs, and to the authors of the individual commodity profiles. Jim Norman, member SME, of Tetra Tech, is the industrial minerals annual review editor.Joe Garska, member SME, of Imerys, is chair of the Industrial Minerals &Aggregates Division’s Technical Committee.The technical committee vice chairs include:• Hyunjung Kim, member SME, of Chonbuk National University, agricultural materials.• Xihui Lin, member SME, of Kemira, ceramics and refractory materials.• Nikhil Gupta, member SME, of Virginia Tech, chemical raw materials.• Adam Rodriquez, member SME, of Penn State, construction aggregates.• LeDeana Roberts, member SME, of Imerys, fillers and pigments.• Harsha Kolla, member SME, of ChemEOR, sorbents, filters and process aids.• Edgar Blanco, member SME, of FLSmidth, specialty minerals.Their help makes possible this July industrial minerals issue. On behalf of ME readers, the editors thank them.During the past 25 years, U.S. ball clay production (the quantity sold or used by domestic producers) increased from 788 kt (869,000 st) in 1990 to an alltime high of 1.31 Mt (1.44 million st) in 2003 (Fig. 1). Housing construction within the United States, a leading market for ball clay-based ceramics and sanitaryware, began to decline in 2005, which resulted in a considerable decrease in sales of ball clay that continued through the 2008-2009 economic recession. After bottoming out at 831 kt (916,000 st) in 2009, ball clay production steadily increased through 2015 (Fig. 1). Estimated sales in 2015 were 36 percent higher than those in 1990 and 18 percent lower than those in 2003.Four companies (H.C. Spinks Clay Co., Imerys S.A., Old Hickory Clay Co., and Unimin Corp.), mined ball clay in five states during 2015. An estimated 1.7 Mt (1.18 million st) of ball clay valued at an estimated $47.5 million was sold or used by U.S. producers, a 4-percent increase from 1.03 Mt (1.14 million st) valued at $45.2 million in 2014. Approximately 65 percent of total ball clay production was air-float, 25 percent was crude or shredded and 10 percent was water-slurried"

Jul 1, 2016

By H. Zhu, F. Xu, T. Wang

Abstract : The deformation monitoring data of the middle pier of the in permanent ship lock in Three Gorges revealed several interesting deformation phenomena. Conclusions and explanations are made concerning the phenomena in this paper, based on the finite element and engineering geology analyses. Firstly, the fluctuation of the horizontal transformations can be attributed to the alternate excavation of the two neighbouring ship lock rooms. Secondly, the rock mass discontinuities result in the displacement breaks. Lastly, the main reasons for the one-sided leaning phenomena are the natural stress, which is not evenly distributed, and the presence of discontinuities. This paper presents a valuable reference for studying the ‘individual phenomena’ in geotechnical engineering. ZUSAMMENFASSUNG: Die Beobachtungs claten an der Mittelpier deformation bezüglich Permannenter Schiffsschleuse in den Drei Schluchten offenbaren einige interessante Deformationsphänomene. Die Schlußforgerungen und Erklärungen dazu in dieser Arbeit basseren methodisch anf der ‚’ ‘Endlichen-Elemente-Analzse’ und der ‘Ingenieurnissen-Geograhnie-Analzse’. Erstens kann die Fluktuation der horiyontalen Transformation durch die ungleichzeitige Ausgrabung der zwei benachbarten Schiffsschleusenräume verursacht werden. Zweitens resultzert die Diskontinuität der Felsenmasse ans dem verlagerten Bruch. Drittens: Die Hauptgründe für das Zu-einer-Seite-Neigung-Phänomen in manchen Stellen sind der ungleich eigeteilte natürliche Druck und das vorhandersein der Diskontinuität. Diese Arbeit präsentiert eine wertvolle Referenz für die Untersuchung der Sonderfälle in geotechnischen Bau. Résumé: Cet article a analysé sérieusement et profondément , en utilisant des procèdes d’étude par exemple l’analyse d’éléments défini et celle de la condition géographique de traveaux , des règles typiques de la déformation montrées dans les données surveillantes à propos de la déformation des pierres centrales dans les écluses éternelles du Trois Gorges , on en a tiré une conclusion : 1) le changement des chiffres des déplacements horizontaux des pierres centrales est causé par les creusages séquentiels des cannelure voisines ; 2) l’inclinaison au Nord de toutes les pierres centrales entre les deuxième et troisième chambres d’écluse est causée par la différence de la gravitation entre les deux chambres d’écluse et par l’existence de la surface structurale ; 3) l’existence de la surface structurale cause le changement des chiffres des déplacements horizontaux des pierres centrales au niveau profond . Cet article donne une référence utile pour l’étude du ‘ problème d’indivudualité’( ou les situations anormaux) dans les données surveillantes de la déformation des pierres centrales de la génie civile.

Jan 1, 2003

By R. Schuhmann

Jan 1, 1965

By Debasis Deb

The first version of the longwall strata control and maintenance system (LSCMS) has been successfully developed by the Strata Control Re¬search Team at the University of Alabama. The system includes a software package designed to monitor shield leg pressure, interpret the data and predict the forthcoming roof loads and the existence of geological anomalies. It can also detect maintenance problems of the face equipment. The LSCMS was installed underground and connected to the surface terminals at Drummond's Shoal Creek Mine in Alabama. The system has proven to be a useful and practical system for improving safety and efficiency in coal-mining operation. The Shoal Creek Mine is a new, large coal mine operated by Drummond with two longwall panels. The Blue Creek seam is the primary source of coal production. It is located at a depth of 275 to 440 m (900 to 1,450 ft) below the surface with an approximate 2% southwest dip. Typical strata conditions are represented by two stratigraphic columns (Figs. la and b). A fireclay/dark shale parting (called Middleman) 0.2- 0.7-m- (1- to 2.5-ft-) thick exists between the Mary Lee and Blue Creek seams. Mining conditions vary from area to area. This mainly depends on the Blue Creek seam thickness that ranges from 0.9 to 2.9 m (3 to 9.5 ft). The thickness of the Mary Lee and the parting is relatively consistent with a to¬tal of 0.9 m (3 ft). They are mined when the Blue Creek seam becomes thinner. In most of the panels, the immediate roof is composed of sandy shale 1.5-

Jan 1, 1997