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By G. V. Basham

"Environmental audit" is a phrase that can raise the blood pressure of otherwise cool and calm corporate personnel. There is widespread concern that any organized effort to find environmental problems will do so and may result in the imposition of substantial liability against the business that engages in such activities. However, such audits can reduce rather than enhance possible liability. Relevant issues include: the role of the attorney in the process, liability risks associated with environmental audits, steps to maximize confidentiality of audit results, reporting requirements and use of audit results in a proactive manner.

Jan 1, 1995

By Maurice Jackson et a1

Golder Moffitt and Associates (GMA)", were commissioned to reassess a large metallic low grade orebody. One of the aims of the study was to estimate recoverable reserves. Recoverable reserves are here defined as ore reserves for a specific mining block size. The mining block is that block on which the decision that the material is ore or waste is made. Recoverable reserves take into consideration mining methods. New methods for solving this type of problem were recently developed in Geostatistics and so for this reason GMA called for the technical assistance of the Centre de Geostatistique (C.G). The complete estimation was done using the geostatistical techniques and programs of the C.G together with some of the programs of GMA. As the mine was in production at the time the study commenced it was-possible to make frequent checks on the estimated values using blast-hole data. The ore reserves were also estimated using the more conventional interpolation method of inverse square of distance weighting.

Jan 1, 1979

By K. Biswas, H. C. Lee, S. J. Jung

Ore passes are circular openings excavated in rock for in-mine gravity-transportation of ore. It is a very important component of the overall load-haul system of an underground mine. The function of an ore pass is two-fold: first, gravity-transportation of ore from the extraction level to the haulage level and second, the loading operation at the haulage level utilizing the gate assembly. In reality, like any other system component, an ore pass breaks down either due to a hang-up within the ore pass or due to a failure in the gate structure. The failure of the gate assembly may be attributed to a greater extent to the impact load as experienced by the components of a gate structure as a result of the direct impacts of the rock fragments and to a lesser extent to the static or 'dead weight' loads of the accumulated materials in the ore pass. This paper uses simulations in Working Model® as an aid to investigate the effect of both the impact and static loading on the gate assembly and on the inner-walls of the ore pass. The paper also investigates the impact of ore pass inclination and the presence or absence of dogleg on the static and impact loading of the same.

Jan 1, 2002

By Prasad Kummarapurugu, Maija Teijonsalo, Sirkka-Liisa Jamsa-Jounela

There has been a significant progress in the use of mathematical modeling and simulation in the minerals industry in the last decade. Process models have moved from academic world to important industrial tools. This paper reviews the status of mineral processing simulators and recent progress in simulator development and applications is discussed. The simulation for process design and optimisation is now an established technique, as evidenced by its increasing use of practising engineers through commercially available simulator software. The paper presents a systematic approach to the process study procedure for the control system development, clarified by practical case examples calculated by SimCon - a novel steady-state simulator for mineral processes. Examples of the application of SimCon in drawing flowsheets, calculating mass balances and making simulations for grinding and flotation processes are presented. At the end of the paper, the state-of-the-art and the future of computer-aided pro- cess study at mineral processing plants is discussed. Keywords: Simulators, modelling, object oriented programming, computer aided control system design

Jan 1, 1996

By Val Ness, Leonard Harris

Mentoring is defined as close counseling by an experienced and objective advisor within the industry. It is one aspect of attracting the best candidates into the minerals industry, holding their interest, and encouraging stable career growth. By encouraging proper mentoring practices, we foster strong careers, we transmit important wisdom to the next generation, we fortify the industry with better talent, and we encourage the best possible advocates for the minerals industry. This paper illustrates the consequences of poor mentoring, offers an example of positive mentoring practice at the college or university level, reviews some guidelines for stable and fruitful mentoring, and proposes a plan to spread appropriate mentoring practices. Authors' note: The use of masculine pronouns is for convenience and simplicity only. Our best engineers and managers come from both genders, and the authors intend no slight to either one.

Jan 1, 2001

By G. G. O. O. Uwadiale

A number of Nigerian iron ore deposits have been upgraded to the specifications of concentrates for the blast furnace and the direct reduction iron- and steel-making plants. Depending on the mineralogy of the ore deposits, the techniques of oil agglomeration, magnetizing reduction, washing and scrubbing, gravity concentration, and reverse froth flotation have been utilized. A mode of distributive management of the deposits, in the direction of their technoeconomic utilization in the country's developing iron and steel plants, is presented.

Jan 1, 1990

By Y. J. Wang

The concept of subsystem characteristic curves for multiple-fan ventilation networks is presented through the construction of characteristic curves for two-fan, series-parallel networks. By considering fans as the individual network branches, the multiple-fan network is viewed as consisting of two components: any one fan branch, which is called the reference fan branch, and its associated subsystem. Thus, F subsystems can be designated for the network with F fan branches. Each subsystem contains one or more fan branches. The subsystem characteristic curve is the pressure-vs.-quantity curve of the subsystem. As illustrated in the example networks, the subsystem characteristic curve is not a strictly increasing curve and does not pass through the origin. The intersection of the characteristic curves for the subsystem and the reference fan branch represents an operating point. Multiple intersections therefore represent multiple operating points.

Jan 1, 1994

By Lawrence A. Ph. D. Hansen, J. David Deatherage

Laboratory testing programs were conducted to investigate the performance under compression loading of several types of geomembranes and geotextiles proposed for use in heap and dump leach projects. Synthetic liners of several thicknesses were sandwiched between representative subgrade soils and cover materials, thus modeling in the laboratory the actual installation conditions expected. Performance was evaluated by visual inspection and vacuum testing. Several testing procedures and equipment were used to investigate the effect of these testing parameters on the predicted performance.

Jan 1, 1987

By C. E. Capes

Reduction in the quality of resources and attendant increase in the quantities of fines to be processed present a major economic and environmental challenge for resource - based industries. It is becoming evident that agglomeration by immiscible liquid wetting will play a significant role in the treatment of these fines. Liquid phase agglomeration can be adapted to separate solids or liquids in highly divided form from liquid suspensions and emulsions. Diverse opportunities in coal fines recovery, novel fuels technologies and oily waste water treatment are cited here. The oil agglomeration of extreme fines from coal tailings, with consequent dramatic reduction in refuse for disposal, is now a commercial reality. It is suggested that this approach can serve as a prototype for the processing of extreme fines in an economical and environment ally sound manner.

Jan 1, 1989

By Edgar E. Vidal, Patrick R. Taylor

Standard textbook equations for heterogeneous kinetics typically utilize a constant driving force to solve for rates and times of reactions. In order to more closely model real systems, equations and solutions are presented for particle leaching kinetics in which the driving force is decreased as the reactions proceeds. In addition, models for continuous co-current and continuous counter current aqueous-solid reactions are presented.

Jan 1, 2005

By Rainer Alles, Markus Keller

INTRODUCTION For overland conveyors of several kilometres length and as well as wide for conveyors designed for high mass flows, the cost for the conveyor belting share is 40% to 50% of the invested cost 173. The German Standard DIN 22101 is used for calculation and dimensioning of - conveyor belts and belt conveyor components. Developments in rubber technology and conveyor belt design required a revision of the standard released in 1982 121, which was published in August 2001 131. New research results and publications 16-9, 13-15] led to a better understanding of the material behaviour and their influences on conveyor belts. Test and calculation methods have been established to determine the most important parameters which are related to the performance of a conveyor belt line. These parameters are • The running resistance of the idlers • The indentation resistance of the belt • The dynamic splice efficiency • The distribution of belt load in the splices, transition zones and on pulleys. As a result, new rubber compounds with low indentation losses allow the use of reduced friction coefficients and thus lead to reduced power consumption, smaller drives and lower belt tensions. The deeper understanding of the flux of forces within belt splices led to both optimised splice design and optimised rubber compounds which significantly improve the dynamic splice efficiency. Therefore, in accordance with the standard, the benefits of these technologies and the better understanding of material behaviour allow a reduction of belt strength still maintaining sufficient safety factors. Thus engineers are enabled to calculate belt tensions more exactly and users are encouraged to pay more attention to starting and braking techniques. DETERMINATION OF DRIVE FORCE According to the DIN standards the resistance to motion generally has to be determined for each different section of the belt conveyor including upper and lower run separately. The necessary drive power P is calculated as [ ] with v as the conveying speed. The total of all resistances to motion of carry and return run can be determined as [ ] FHo and FHu are the primary resistances consisting of the running resistances of the idlers, the indentation resistance of the belt, the fulling of the conveyed material and the flexure of the belt. While indentation resistance and idler resistance are measurable, they have been deter- mined to be responsible for up to 70% of the primary resistances covered by FH. Further FN is the secondary resistance that covers, for example, the resistance of feeding points and scrapers. Fa are the total slope resistances and Fs is the total of all special resistances, resulting, for example, from belt steering devices. These three resistances should be neglected in the following discussion. For conveyors where a determination of the substantial parts of the resistances to motion is not possible, according to the new DIN standard [31 a determination of the drive power is acceptable by using the fictitious friction factor) [ ] In this formula the index i identifies the individual section of the conveyor, 1 is the length of the section and MR, MG and ML are the related masses of the idlers, the belt and the load in kg/m. The fictitious friction factor f determines the ratio between the overall resistance to motion and the total of moved masses within the

Jan 1, 2004

By Joe Maloney, Steve Shadow

Mining conditions at Cyprus Amax's Twentymile Coal Company (TCC) require the use of regenerative conveyors. Regenerative conveyors were first used in the Southwest Mine District and then in the challenging East Mine District. This paper will discuss the development and refinement of the equipment used to brake the regenerative conveyors.

Jan 1, 1998

By D. Kump

Barrick closed the Bullfrog Operation in November 1999.During its life, the Bullfrog produced ore from three open pit mines and an underground mine; 32,000,000 tons of ore were processed at the 9,000-ton per day oxide mill. The mill tailings were deposited in a 320-acre tailings impoundment. When operations ceased, an estimated 750,000,000 gallons of water remained to be removed from the tailings impoundment. During operation, the drain down water from the tailings impoundment was pumped back to the mill for reuse; since closure of the mill, the drain down water has been managed by a combination of passive and forced evaporation.

Jan 1, 2004

By J. K. Whyatt

A microcomputer controlled data acquisition system has been developed for automatic monitoring of underground instrumentation from a remote location. The system has been used extensively by Spokane Research Center personnel for monitoring rock instrumentation in shafts, drifts, and stopes in hardrock and coal mines, especially where instrument access is limited. Ruggedness was a major consideration in designing the underground portion of the system and it has performed satisfactorily under extreme environmental conditions, including temperatures to 1100 F, 100% humidity, and falling water. The major advantage of the system is that it multiplexes the data from 16 channels through a single twisted pair cable to the receiver, significantly reducing cabling requirements. This receiving station can be as far as 8,000 ft from the instruments without the addition of line drivers. The receiver maintains a data buffer with the latest scans, which is periodical 1 y accessed by a micro- computer, either locally or through a modem, that automatically records and reduces the data. Utilities allow on-site plotting of data and uploading of data to mainframe computers.

Jan 1, 1986

By James M. Prudden, Jon C. Sprague

Valdez Creek Mining Co. properties consist of multiple intersecting paleo-placer channels containing appreciable quantities of coarse gold. Reverse circulation drilling, combined with geophysics, is used for both exploration and development reserve determination. Classical drill-blast-load-haul open pit mining techniques used for the 22,000 cubic yard per day production schedule required modification to compensate for arctic winter operating conditions. High wall stability problems within the glacial sediment overburden necessitated developing multiple dewatering methods and variable pit slope designs to eliminate unstable pit wall conditions. Processing mine run fluvial gravels utilized a classical winter protected screening plant-sluice box recovery system enjoying high metallurgical recoveries and zero discharge tailings disposal.

Jan 1, 1987

By R. Poulin, R. C. Pakalnis

Approximately 51 % of all ore production in Canadian underground metal mines is derived directly from open-stope operations. This method requires that large excavations remain open until the ore is extracted with a minimum acceptable level of dilution. A survey of underground mines in 1988 reported that a major factor in their closure was uncontrolled dilution. It has been reported that 40% of openstope operations were experiencing dilution in excess of 20%. This level of dilution has significant implications on the economic viability of a project, especially when one considers that a rate of return on a positive project is generally between 10% and 20%. This paper reports on the various definitions of dilution, on the methods of stope design that are presently used with the objective of reducing dilution and on a recently available survey technique that enables dilution to be quantified.

Jan 1, 1996

By M. Manrique, S. A. Pirzada, P. R. Taylor

A thermal plasma-assisted laminar flow reactor was used to evaluate the kinetics of converting alumina to sodium aluminate in flight. Free energy minimization calculations were used to determine experimental conditions. The experimental variables included alumina particle size, alumina/sodium nitrate molar ratio, temperature and residence time. A mathematical model for the conversion was developed and validated. Experimental and mathematical results are presented.

Jan 1, 1998

By M. J. Gula, S. S. Xue, E. P. Horwitz, J. T. Harvey

A study was conducted to control iron in copper electrolyte streams using Eichrom Industries' new monophosphonic/sulphonic acid resin. The resin strongly and selectively extracts ferric ion over copper and cobalt from highly acidic copper electrolytes. The resin has a loading capacity of 27-g/L iron and can be readily regenerated. In addition, the new resin can easily be synthesized using commercially available starting materials. This paper presents the experimental results for iron control in copper electrolyte streams using the new resin and discusses its potential applications to other hydrometallurgical streams.

Jan 1, 2002

By D. Dunbar

The flooding of open pits is now receiving considerable attention from the mining industry as an option that may minimize environmental impacts, particularly when anoxia in pit-lake deep waters can effectively eliminate oxidation of pit-wall sulfides. This paper describes a state-of-the-art, coupled physical-geochemical pit-lake model. The model is used to verify that a controlled, two-stage infilling of the open pit at the Kori Kollo gold mine, southeast of La Paz, Bolivia, would result in a cost-effective, environmentally responsible closure strategy. By filling the pit initially with highly saline surface waters and naturally saline deep groundwater and then capping with fresh river water, a very stable and strongly stratified pit lake will be developed. In addition, the stratification will result in the isolation of metal-rich saline bottom waters from surface waters of good quality. Results of this model provide defensible predictions of the physical stability and evolution of water quality in the Kori Kollo pit lake over time. The model results indicate that anoxic conditions will develop below the fresh-saline water boundary within one to two years, followed by the rapid onset of sulfate-reducing conditions in the bottom waters. Hydrogen sulfide produced by sulfate reduction will readily react with dissolved metals to form highly insoluble metal sulfides. The process results in the gradual removal of metals from the water column and the concomitant improvement of water quality over time. A notable benefit of this strategy is that it can be fully integrated with other mine site closure options as well as future environmental-management strategies. The proposed plan allows for the safe isolation of saline waters, the potential for passive treatment in anoxic bottom waters of ARD seepage from other mine site operations, should they arise, and a repository for future reactive wastes that could be effectively isolated in a physically and chemically stable environment.

Jan 1, 2003

By M. M. Hajdasinski

In his recent paper, Torries (1998a) came to the defense of the much-criticized internal rate of return (IRR) as a project evaluation and ranking criterion. Torries also offered his own approach to the IRR-based project ranking, which he believes to be a more practical alternative to the conventional incremental-ranking approach, which Torries considers to be misleading. In an earlier paper (Hajdasinski, 2000), the author demonstrated that Torries' arguments vindicating the IRR concept are invalid. This paper provides logical and numerical evidence that the same is also true with regard to Torries' IRR based project-ranking approach.

Jan 1, 2000