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By J. Kelleher, R. Saulters, K. H. McDaniel, L. Griswold

To improve underground safety and visibility during mining applications, the Waste Isolation Pilot Plant designed and built a dry-dust filtration unit. The unit works in conjunction with a Spendrup 1120-70 fan with ventilation tubing to filter the face exhaust air during mining operations. The closed- loop system is designed to filter 17 m3/s (36,000 cfm) and is intended to screen 10- µm (1,250 mesh) and larger particles at 90% efficiency. To accomplish this, the unit uses a combination of Dollinger Staynew Inertial Spin filters, cyclones and traditional mesh filter media.

Jan 1, 2002

By James Sheridan

Risk can generally be defined as the possibility or chance of a loss corresponding to uncertainty. Analysis is the process for examining the components and relationships of a complex system in order to determine the impacts of its variables. Risk analysis is therefore a course of action taken to analyze multiple variables of a system that is subject to speculative outcome. When risk analysis is applied to mine development, it becomes the means for assessing and measuring those parameters that contribute to economic viability. Mining can be a risky business. It is composed of an assortment of factors that contribute to its financial outcome. Of these factors, the most consequential output is the net present value (NPV). Applying risk analysis in mine development can identify those factors having the most significant impacts and applying limits to those impacts. Mathematical computer modeling using Monte Carlo techniques is available and can be customized to suit specific mine development ventures. Essentially, those parameters that are not fixed values can have input variability. Rationally deduced engineering estimates should be the basis for determining the initial values applied as inputs in the models. Risk analysis therefore provides the user a means to identify, rationalize and assess the risks in mine development in an informed, calculated, and unbiased format for making economic decisions.

Jan 1, 2002

By R. Heersink, C. H. Wells

Innovations in communications and real-time information systems are providing industry opportunities to improve profitability. Real-time operating data is collected from equipment across a site or even several sites into a central server for secure PC and PDA-based Internet access. This paper includes discussion of how operating staff can use wireless devices to see equipment and processing data from anywhere throughout the mines and concentrators, and how management can view results from multiple mines, all in real time. Additional opportunities enabled through the remote access by equipment vendors or mining consultants is also presented, as well as an overview of typical benefits and current installations.

Jan 1, 2002

By J. H. Heintz

This paper discusses the law as it relates to appraising operational mining properties in the context of a takings claim. Topics include the need for valuation expertise, the differences between de jure and de facto takings, an overview of the law of condemnation, including jurisdictional issues, and defining your strategic options according to the controlling statute. State condemnation law varies by jurisdiction and just compensation can be calculated by comparable sales unit-times-price, before ¬after-valuation, capitalization of income and discounted cash flow methods. Takings under Federal laws are reviewed, as is the necessity of assembling a team including attorneys, valuation experts including a mineral appraiser, a real estate appraiser, economists and geologists.

Jan 1, 2002

By K. E. Lasaridi

Increasing soil organic matter was considered to be an important factor for the establishment of vegetative cover in abandoned quarries of perlite and bentonite in the island of Milos. For this reason, the feasibility of composting local organic wastes and by-products for use as a soil amendment was examined in this study. A mixture of organic wastes of vegetative origin and seaweed, in proportions that correspond to local material availability, was composted in laboratory scale reactors and the composting progress and compost quality were evaluated. Temperature, airflow and respiration rate were continuously monitored and various compost quality parameters, such as C/N ratio, nitrate nitrogen and seed germination were analysed. Addition of inorganic nitrogen was necessary for the biodegradation of the substrate, while the main problem for the compost utilisation was related to its high electrical conductivity, characteristic of seaweed containing mixtures, which further increased with nitrogen addition.

Jan 1, 2002

By David J. Kruse

Although it may be perfectly acceptable to neglect the belt's elastic behavior for many conveyor designs, this can lead to disastrous consequences for others. So how can a designer know in advance if a dynamic analysis is required? Unfortunately, in many cases it is impossible to foresee or predict dynamic problems prior to performing the actual analysis. However, a basic understanding of the principles of conveyor dynamics, as well as knowledge regarding common problem areas, can significantly help the designer make more educated decisions during the initial design stage. This paper will demonstrate how static calculations alone can incorrectly represent the true behavior of the conveyor system. It will also discuss the importance of correctly sizing and locating the take-up system to provide the most economical conveyor design. The use of capstans will also be discussed followed by two examples demonstrating their proper operation.

Jan 1, 2002

The authors summarise the development and recent advances in the reconstruction and visualisation of three-dimensional objects from point data and describe applications to the reconstruction of orebody shapes from drill-hole and other data. In particular, Dijkstra's algorithm is proposed and implemented as a means of optimal reconstruction of complex orebody and topographical shapes from irregularly located sample data. The surfaces of the shapes are constructed from triangular tiles and the algorithms proposed by the authors are guaranteed to find the optimal set of tiles that "best" construct the surfaces on the basis of specified objective criteria. The algorithms are illustrated by applications to a complex silver/gold/zinc/lead deposit.

Jan 1, 2002

By D. G. Klaren

Self-cleaning fluidized bed heat exchangers are conquering the world for reason that they are able to solve any severe fouling problem in indirect heat transfer due to the circulation of cleaning particles through the tubes of vertical shell and tube exchangers. In most cases, these particles consist of chopped metal wire. Moreover, self-cleaning fluidized bed heat exchangers perform with excellent heat transfer at very low liquid velocities, which makes completely new designs of shell and tube configurations possible. Further, self-cleaning fluidized bed heat exchangers show a strong shear thinning effect in non-Newtonian liquids. All the above characteristics make the self-cleaning fluidized bed heat exchanger an ideal tool for the indirect heating of laterite nickel slurry in High-Pressure-Acid-Leach (HPAL) plants. Preliminary tests and evaluations of these heat exchangers have shown that the performance and price of these heat exchangers used for the production of nickel and cobalt from a laterite slurry, cannot be matched by existing conventional heat exchange systems. This article explains the principle, design, lay-out and enormous advantages of the self-cleaning fluidized bed heat exchange technology in a plant suitable for an annual production of approx. 45,000 ton nickel and 4,500 ton cobalt from laterite slurry through high pressure'acid leaching.

Jan 1, 2002

By Michael G. Nelson, Brandon J. Peterson

Currently, decisions made by mine management are usually based on economic analysis and predetermined rating systems and tables. As financial and other constraints on mining operations become more severe, more accurate methods are required. Discrete-event simulation programs have been used successfully in many mining applications, including the simulation of open-pit, truck-and-shovel operations. However, these simulations could not model complex systems well enough to provide the detailed modeling of the haulage roads and other mining operations that is needed today. The recent advances in computing technology combined with the recent abilities of simulation to realistically simulate complex systems and visually present results in 3D have made simulation a more detailed and valuable aid in the evaluation of mining projects.

Jan 1, 2002

Traditional fine-grinding mills in mineral processing rely on the use of steel medium for particle size reduction. The IsaMill (a horizontal stirred mill with a 3, 000-L net chamber volume and a rated motor power of 1,120 kW) has successfully adopted a novel product-separator design, which has led to a major revision of medium use in fine grinding. The IsaMill separator has successfully operated with a wide variety of medium types, such as silica sands, river gravel, smelter slag, run-of-mine ore fractions and steel shots, with sizes ranging from 0.5 to 10 mm. Great flexibility in the IsaMill operations has been achieved for processing feed as coarse as 120 µm to a product as fine as 5 µm. This paper discusses the performance of two inert grinding media in the IsaMills that are used at Mount Isa Mines Ltd. for the processing of galena- and sphaleritebearing ores to below 10 µm. They are the copper reverberatory furnace slag (CRFS) and the heavy-medium plant rejects (HMPR). A methodology was also demonstrated for comparing the medium performance and for scaling up the IsaMills from a 1.5-L laboratory batch mill to a full-scale 3,000-L mill.

Jan 1, 2002

By S. Ersayin, I. Iwasaki

Application of a magnetic field was shown to be effective in controlling iron losses in pilot-scale cationic silica flotation in the processing of magnetic taconite concentrates. The design of a magnetic field distribution device and batch flotation test results using a 1.42m3 (50 cu. ft.) WEMCO cell are reported. Major losses of iron units in froth products were in the -25µm (500 mesh) fraction, and the application of a magnetic field decreased the flotation of fine magnetite, thereby improving the selectivity of separation. The “as received” sample was sufficiently magnetized and no further benefit was gained by magnetizing treatment. Selectivity was somewhat adversely affected by demagnetizing the sample, though its effect was minimal due to the magnetic field. The device is simple in construction, low cost and may be installed readily in existing equipment.

Jan 1, 2002

By K. M. Stone, N. J. G. Masson, A. C. Woollett

The Jabali zinc deposit, in Yemen, contains at least 9.4 Mt at a grade of 10.7% zinc, 2.2% lead and 77g/t silver. The zinc occurs as smithsonite with minor hydrozincite. The Jabali ore does not produce a zinc concentrate of sufficient grade to be acceptable to conventional smelter/refineries, and it has been necessary to formulate a less conventional development plan. This involves the construction of a mine and concentrator at Jabali and a metal production facility using a new flowsheet designed specifically for the treatment of oxide material, at Yanbu, in Saudi Arabia. In order to give the facility the necessary economies of scale, the Jabali concentrate will be supplemented by feed from other deposits, this may be either oxide or sulphide material. The paper outlines the geology and proposed mining and treatment operations at Jabali, the flowsheet for Yanbu and presents preliminary costs for both operations

Jan 1, 2002

By E. Cetin

The authors describe the general problem of cut-off grade optimisation for multi-mineral deposits and outline the use of genetic algorithms for optimal cut-off grade schedules for deposits with up to three constituent minerals. Case studies are given and a comparison is made with Lane's multi- mineral cut-off grade algorithm.

Jan 1, 2002

By Steve Kral

U.S. mines are among the most efficient, productive and safest in the world. Much of that efficiency is due to the high-technology equipment and processes available to the industry. The U.S. mining industry can produce more material now with fewer people than it could a few decades ago. And that material can be produced more safely. However, the workforce is growing older and fewer young people are filling the holes created by retirements. Even though mining is one of the highest paid occupations in the United States, young people believe they can find jobs that pay almost as well without the risks and the often remote locations associated with mines.

Jan 1, 2002

By D. Bour, C. Nyikos, R. Curtice

Fire in a coal mine can be disastrous on many levels. In most cases, when a fire is detected, mining operations cease and all personnel are evacuated. Underground coal-mine fires are difficult to extinguish, can burn for a long time, and often result in an extended period of lost production. In a worst-case scenario, the mine is permanently sealed and abandoned, resulting in lost jobs, lost natural resources, and possible devastation of the local economy. In some cases, seals placed within the mine to isolate the fire could eliminate the need for sealing the entire mine and the subsequent extended delay in returning the mine to full operation. Previous attempts to place remote seals to extinguish mine fires in active mines have been largely unsuccessful. The West Elk mine experienced an underground fire in early 2000. The fire could not be accessed and extinguished from the active mine workings. A method of constructing seals remotely by drilling boreholes into the affected area was needed to help isolate and extinguish the fire. This paper describes the process by which remote seals were constructed that successfully isolated the fire and provided a means of extinguishing the fire by flooding the area with water. The period of lost production in the West Elk mine was considerably shorter than is typical in similar situations.

Jan 1, 2002

By H. K. Lin

Cyclic voltammetric and potential step chronoamperometric techniques were used to study gold dissolution in cyanide solution. Three distinct anodic peaks and one cathodic peak appear on the voltammogram between -0.50 and 0.80 V vs. SCE. The corresponding reactions were proposed to explain the peaks and the passivations. The proposed reactions were in agreement with the effect of pH and cyanide on the magnitude of the peak currents. Cyclic voltammetric tests, with various vertex potentials, were also conducted to examine the proposed reactions. Steady-state currents at various potentials were obtained by potential step chronoamperometric technique and were compared with transient currents obtained by the cyclic voltammetric technique.

Jan 1, 2002

By R. W. Chappell, M. W. Hills, R. L. Olsen

A stochastic approach was developed and applied to the Butte, Montana Hillside abandoned mining site for modeling stormwater runoff and subsequent receiving stream loadings. This approach enabled capture and quantification of the uncertainty associated with stormwater quality data and allowed the prediction of copper and zinc concentrations in the receiving stream caused by runoff from the Butte Hillside during storm events. Runoff flows and stormwater concentrations were input to the model as probability distribution functions. Monte Carlo simulation allowed prediction of expected instream concentrations in the form of cumulative distributions functions. The modeling results allowed evaluation of current best management practices (BMPs), targeting of future BMPs, and identification of key data gaps to fill during future sampling activities. This modeling approach is considered extendable to other active and inactive mining sites. Output from a model of this type is easily understood and can be used to communicate effective stormwater management to site regulators. Furthermore, application of this modeling approach will facilitate the development and implementation of a site-specific stormwater management plan and will optimize efforts to achieve standards for compliance with stormwater discharge permits.

Jan 1, 2002

By A. Dale Wunderlich

Since Sept. 11, 2001, the author has been asked by several mining companies and mining publications to share some of his insights on how the terrorist attacks on the World Trade Center (WTC) and Pentagon might affect the mining industry globally. Until now, the author has been reluctant to express his thoughts in a publication that could possibly fall into the hands of terrorists and give them some ideas that they may not have been previously considering. However, the author discussed the contents of this article with several friends and acquaintances in the international intelligence community. They said that nothing commented on here is new to the terrorists. Potential terrorist targets Sources within the worldwide intelligence gathering community have told the author that current intelligence data indicates that it is likely that the Islamic fundamentalist groups responsible for the attacks on Sept. 11, 2001will likely be directing their effort at foreign business entities. Any overseas or any domestic businesses of highly visible companies that are part of the anti-terrorism alliance should consider themselves a potential target.

Jan 1, 2002

By Ryan Lemmon

Belt turnovers are commonly used in conveyors to rotate the belt so that the clean side of the belt contacts the return idlers. The belt turnover length has traditionally been sized on only the twisting stresses. However, belt turnovers are also subjected to bending stresses due to the weight of the belt. Although bending stresses have in the past been ignored, these stresses are significant and should not be neglected. This paper quantifies and presents a method for calculated twisting and bending stresses and also the belt sag.

Jan 1, 2002

By F. G. Rinker

World demand for metallized iron continues to increase, keeping pace with steelmaking requirements for lower-cost hot metal. Virgin iron ore and in-plant oxide fines can be reduced to direct reduced iron (DRI) and hot-briquetted iron (HBI). Maumee Research & Engineering Inc. (MR&E) developed an improved coal-based process for the cost-effective production of either DRI or HBI. Starting with dry compaction, the process combines the latest technology for material preparation, rotary hearth furnace construction and environmental control. Coarse iron ore fines are blended with pulverized nonmetallurgical coal to produce a highly metallized (>90%) product. This paper presents production and installation cost data based on operating and under-construction iron oxide reduction facilities.

Jan 1, 2002