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By R. P. King

INTRODUCTION It is now 21 years since Wiegel and Li published their paper on a random version of Gaudin's model for the mineral liberation phenomenon (Wiegel and Li, 1967). This paper was to revitalise interest in North America in one of the most fascinating, difficult and important problems in the field of theoretical mineral processing. Gaudin had many years previously (Gaudin, 1939) already presented a penetrating analysis of the problem and Wiegel and Li based their analysis very closely on the Gaudin model but they realised that the indeterminate geometrical structure of mineralogical materials demanded that only probabilistic models could provide the necessary quantitative information when working with real materials. They proposed and solved a randomised version of the Gaudin model but retained the essential geometrical simplicity of cubic mineral grains and a cubic fracture pattern. Although their model met with some limited success it was to be superseded in due course. During the 1940's and 1950's the classical field of geometrical probability spawned the mathematical discipline of integral geometry and as early as 1965, Bodziony (1965, a,b) showed that the techniques of integral geometry could accommodate the problems associated with the indeterminate nature of the geometrical mineralogical structure, provided that these were couched in probabilistic terms. In particular he showed that the quantitative description of the comminution process and that of liberation could be decoupled with the resulting economy of effort. This idea has profoundly influenced the course of research in liberation theory and has greatly facilitated its application and the measurement of liberation in a practical way. Bodziony demonstrated also that any theory that required the specification of the mineral "grain

Jan 1, 1989

By C. McDonald, S. Slottee

Deep "paste" thickeners have been used in the alumina industry for several decades to improve chemical recovery and allow “stacking” of the red mud for disposal. These paste systems have eliminated many traditional tailings ponds in addition to providing better tails washing and better water recovery. This technology is not widely used or understood in other mineral processing applications. However, there is growing worldwide recognition of the advantages of concentrating mill tailings to a “paste”, i.e. a solid suspension that does not settle or segregate. This technology offers several alternatives to the traditional tailings pond such as “stacking” or mine backfill. More water recovery is possible than with high rate thickeners. Process benefits come in the form of better chemical and metals recovery through better washing in counter current decantation (CCD) applications. Obtaining a true paste (non-segregating suspension which exhibits a yield stress) and understanding the handling characteristics for applications outside alumina, are recent developments. Achieving all of the benefits available from a paste system requires careful design that takes into account the specific requirements of the disposal application along with the peculiar difficulties in producing and handling paste. In fact, design of a paste system is markedly different from a conventional system. Project design usually requires the cooperation of experts in several interrelated specialties including geotechnical, thickener design, pumping and discharge design and controls. A successful project must coordinate all activities to ensure that the overall objectives for the project are achieved. This paper describes the properties of paste, reviews the applications, and discusses the design of a complete paste deposition system.

Jan 1, 2003

By Bobby P. Faulkner

Allis-Chalmers has combined a new heat transfer device, called the ROLLER GRATE, with a unique processing scheme, resulting in the ROLLER GRATE Oil Shale Processing System of Allis-Chalmers. In order to test both the process and the equipment, a batch Process Development Unit (PDU) ROLLER GRATE retort was designed and built. This unit vas designed with the flexibility to process shale over a wide range of test conditions in order to demonstrate the attributes of the oil-shale processing system. Instrumentation on the PDU and extensive sampling of the effluent streams permitted the PDU test data to be used in the design and scale-up of the process. Over 30 tests have been conducted with Colorado shale, and over 25 tests have been run with an Indiana shale. In addition, rests have been run with California and Utah tar sands.

Jan 1, 1983

By A. F. Stewart

Slope design in an open pit mine includes the determination of a number of parameters, including bench height, bench face angle and berm width. By way of a case history of two highwall slopes (160m and 220m high) excavated in dipping strata in an operating coal mine, this paper illustrates the influence that bench face angle can have on the stability of an entire slope. The two highwall slopes, the lower of which experienced significant instability, were excavated in essentially the same lithologic and structural environment, with the main differences between the slopes being the angle at which the bench faces were excavated and the excavating methods that were employed. In addition to describing the instability that occurred on one of the pit walls, relevant aspects of the engineering geology, slope design and excavation procedures are described.

Jan 1, 1998

By A. D. Hammond

Until recently, the volumes delivered and unloaded from heap-leaching pads have been estimated by manual methods at Wharf Resources' South Dakota operation. In August 1989, the Engineering Department acquired the MINE-SURVEY software developed by GEM COM Services, Inc. of Vancouver, Canada, as part of a mine planning/grade control software package. The implementation of MINE-SURVEY for pad control resulted in a cost-effective tool to provide accurate and prompt estimates of ore delivered or unloaded from the pads. Volumes can be calculated in a matter of minutes as opposed to hours or days. Another benefit is the ease of comparison of as-build and designed volumes, plotting cross-section in any orientation, importing into AUTOCAD, validation of ore densities and truck factors. This paper describes the application of the MINE-SURVEY systems in heap leaching pad volumetrics.

Jan 1, 1991

Potassic alteration domains of greenstone belt lode gold deposits are characterized by systematic partitioning between different groups of incompatible elements, such that Al, Ga, Th, U, Ti and V are decoupled from K, Rb, Ba, Cs and Tl. The former group of elements have concentrations and interelement ratios in alteration domains which reflect host rock control, implying approximately isochemical behaviour. In contrast, K, Rb, and Ba are strongly coenriched, and linearly correlated over th4ee orders of magnitude in abundance, where K/Rb = 260, and K/Ba = 40: K/Cs (-10 ) and K/T1 (-2x10 ) are also correlated, though more weakly. Lithium abundances, and Rb/Sr ratios are erratic in altered rocks. These interelement trends, collectively, are present in deposits variously hosted by ultramafic, mafic, or felsic volcanic rocks, and sediments or granitoids.

Jan 1, 1988

By Steve Kral

San Francisco, CA will host about 1,500 tunneling and underground construction professionals from around the world during the biannual Rapid Excavation and Tunneling Conference (RETC), June 19-22. These professionals are gathering in a city that has seen much under-ground work throughout its history. And, today, the San Francisco region has more than $4.6-billion in tunneling projects under way. The RETC will include three-and-a-half days of technical programming, complete with proceedings, two short courses, two field trips and a host of social activities. In addition, the accompanying exhibit has attracted 127 exhibitors in 152 booths, an RETC record. The following is a brief list of activities that will take place during the conference. A more complete program is provided in the official showguide that is bound into this issue of Tunneling & Underground Construction.

Jan 1, 2011

By Ebelia Manda, Peter RK Chileshe, Sydney Chinyanta, Abdul Samson, Victor Mwango Bowa

Buttressing is a widely employed control measure for mitigating slope failure in various settings such as openpit mines, road sections, dams, and hilly or rocky terrains. This paper presents a study on the effects of buttressing, specifically concerning slide-head toppling failure. Drawing insights from a case study of slide-head toppling in Zambia, our investigation employs both analytical (limit equilibrium) and numerical (3DEC software) modeling techniques. The analytical and numerical models exhibit notable similarities in their schematics and overall results, revealing a subtle effect of buttressing in controlling slide-head toppling failure. This study contributes valuable insights into the nuanced role of buttressing in slope stability, with implications for optimizing buttress design parameters. While the overall findings suggest a modest influence of buttressing on slide-head toppling failure, further discussions delve into the specific implications and potential refinements for practical applications.

Jan 1, 2025

By Jey K. Jeyapalan

A characteristic common to most tailings dam failures caused by earthquakes or excessive rain storm is that the tailings tend to liquefy and flow for substantial distances as a viscous fluid, with the potential for extensive damage to property and life. Failures of El Cobre, Chile (1965), Mochikoshi, Japan (1978), Aberfan, Wales (19661, Buffalo Creek, West Virginia (1972) are examples of such catastrophic incidents. In these four incidents more than 400 lives were lost, and the loss of property was approximately $200 million. In order to be able to assess the potential for damage in case of such a failure, it is necessary to predict the possible extent of flow slide movement. This paper discusses simple procedures for performing such analyses. Also, in order to illustrate the use of these analysis procedures in tailings dam design, two case histories are analyzed.

Jan 1, 1982

By A. R. MacPherson

The procedure to arrive at an energy efficient autogenous grinding plant is carried out in the following steps: First Step - Determine power requirements to grind a particular ore. This work carried out on small samples ground in a 450 mm diameter Aerofall Hill and the results are checked against a standard Bond Index test. Second Step - A bulk sample from the ore zone is ground in a 1.8 m diameter pilot mill. This work is carried on until the power objectives as indicated from the first step have been realized. Third Step - Correlate the pilot mill data, with the data from the numerous samples ground in the small 450 mm mill and arrive at design criteria for the commercial plant. Ensure commercial mill design will be suitable to obtain similar results as those obtained in the pilot mill.

Jan 1, 1981

By Clyde N. Garman

Historically, Vanadium and Uranium have been precipitated together in carbonate sill circuits. A separation of the salts of the two metals was then made on the basis of the fact that the reduced, salts of vanadium are more solo to and those of uranium lose soluble than the respective salts of higher valence. In practice this was carried out by fusing the precipitated combined concentrate with salt, sodium carbonate and sodium hydroxide with oil soaked sawdust mixed into the charge as the reducing agent. Generally the fusion was carried out batch wise and the resulting slag or glass leached in water. A good, fusion and three or four decantation washes resulted in almost complete recovery of the vanadium in the liquid phase and a very high recovery of the uranium as a dense black U02 solid.

Jan 1, 1962

By Arthur R. MacPherson

Primary autogenous grinding has been in general use for somewhat over 20 years. During this period there have been many highly successful plants built on this principle, while some others have had problems such as: 1. Not performing as predicted from test work. 2. Highly fluctuating tonnage rates. 3. Mechanical problems. 4. High liner wear. Many of the problems with commercial autogenous mills have resulted from improper sampling and testing of the ore during the development period. It is recognized that the fully autogenous mill is very sensitive to any changes in grindability which may occur in the feed to such a mill. The semi-autogenous mill is somewhat less sensitive, but large swings in grindability of the feed require adjustment of ball charge and this cannot be easily accomplished in a short period of time.

Jan 1, 1976

By Sathit Tandanand

Geological differences among various coalfields restrain the applicability of subsidence prediction using existing European methods. To modify these methods for domestic conditions, the Bureau of Mines, U.S. Department of the Interior, developed a method of assessment to evaluate the lithological effects on subsidence in the Northern Appalachian basin by examining data collected from 16 longwall panels in the coalfield. The assessment is partially completed, and the results to date show that the ratio of maximum subsidence to the extraction thickness, known as the subsidence factor, can be expressed in terms of the width-to-depth ratio by a simple exponential equation which has a coefficient tentatively considered as the subsidence index. This index varies with the lithology of a particular site and can be expressed in terms of the percent distribution of weak and strong rocks in the overburden.

Jan 1, 1982

By Jeffery S. Thompson

In this report, the effect of catalytic amounts of activators on gold dissolution in clear solutions with gold disks and with slur­ries of gold ores is presented. Activators are nitrogen and sulfur aromatic heterocyclic compounds, which catalyze the gold dis­solution reaction in cyanide and other lixiviant solutions. Gold dissolu!ion studies in clear solutions indicate that the catalyst must bmd to the gold surface to catalyze the dissolution reac­tion. A concentration dependence for activation is observed· the optimum catalyst concentration depends on choice of activtor lixiviant concentration, and solution agitation. Nitrogen and sul fur aromatic heterocycles catalyze gold dissolution in slurries of gold ores with cyanide and other lixiviants. The typical proce­dures of agitated leach and rolling bottles were used to evaluate gold leaching rates. Activation has been demonstrated with a variety of ore types.

Jan 1, 1996

By Lane White

This is a truly exciting time in surface mining technology. A revolution is coming - a revolution made possible by complete mine management systems working in concert with many devices currently available or in the prototype stage. By the turn of the century, the face of surface mining will indeed be different. Imagine . . . an operatorless drill moving around a blast pattern drilling off rounds in record times ... a satellite-based positioning system and drill data combining to report diggability to a shovel operator based on the position of his shovel in a blast ... a driverless truck warning central dispatch of an impending mechanical problem and being reassigned to the shop ... an infrared detector diagnosing the problem, for which the mine management system generates a maintenance work order and, once the problem is corrected, re-dispatches the truck to the optimum shovel.

Jan 1, 1994

By L. M. English, K. A. El-Nagdy

The mine characteristic curve represents the relation between the airflow in a system and the pressure drop across the system. In a single fan system, this relation can be easily drawn by assuming different values of the airflow and calculating the corresponding pressure drop according to Atkinson’s law. In a multiple-fan system this cannot be done for each fan simultaneously. However, an alternative mathematical method for plotting subsystem characteristic curves on subsystem quantity coordinates is outlined here that achieves this objective. The Hardy Cross algorithm has been combined with a switching-parameters technique and has been used to trace subsystem characteristic curves. An example using four fans in a complex network is presented here. This example illustrates the nature of the problem and the difficulty of detecting unstable conditions in this type of network.

Jan 1, 2001

By A. K. Mukhopadhyay

[The mechanical status of a mine ventilation fan can be monitored effectively through vibration analysis. An expert system can be an effective tool in fault diagnosis for a variety of equipment. Computers have made it possible to implement an expert system to analyze the data for correct and appropriate diagnosis. In addition, vibration analysis can provide important information oil the condition of the machine. This paper discusses an approach for an expert system to determine on vibration analysis, practical problems that can occur with a fan. The frequency of the vibration is the only characteristics considered in the analysis, although other variables are discussed in the paper. Finally, a simple computer program, written in Turbo Prolog, is presented. A friendly query system, menu operation and a disk-resident separate knowledge base are a few of the salient features of this system.]

Jan 1, 1997

By J. Davitt McAteer

Improvements in the control of coal mine dust have occurred over the past 25 years. Simultaneously, dramatic improvements in coal mine production technology have occurred, particularly at mines where longwall systems are in use. Production rates of longwall systems have quadrupled since 1978, and dust generation on these systems has significantly increased. However, technology to address control of the resulting increased levels of respirable dust has not kept pace, and many high-production longwall sections continue to experience problems with respirable dust control. This paper seeks to enlist the entire mining community in the effort to resolve the health problems presented by excessive levels of respirable coal mine dust, particularly on longwall systems. These systems are expected to increase in number and length, and to generate increasingly higher levels of dust as production rates of these systems continue to rise.

Jan 1, 1995

By G. Roy, C. B. Pettersson, S. Nandagiri, D. J. Ivor-Smith

The Coastal Water Authority's 2,740mm/2,590mm (108 in./102 in.) pipeline, known as the Northwest Lateral Project, will transport raw water from an existing pipeline over 14.3 km (8.9 miles) to the City of Houston's East Water Purification Plant. The new pipeline crosses under Houston Ship Channel and Greens Bayou in tunnels at approximately 30.5m (100 feet) and 25.9m (85 feet) depths, which present unique experiences in tunneling under open bodies of water in the Gulf Coast's soft ground conditions. An earth pressure balance TBM is being used for the deep tunnel sections where the ground demonstrates high overload factors and variable conditions ranging from clays to silty sands. This paper discusses the design approach for the tunnels and shafts, ground conditions, constructability, and selection of the primary lining system.

Jan 1, 1989

By P. Somasundaran

Beneficiation by froth flotation, which exploits the difference in surface properties of minerals, has been a promising method for coal cleaning. However, dissolved mineral species present in coal flotation systems can interact with particles and other species leading to drastic effects on flotation. Particularly, precipitation or adsorption of such species on the particles can alter their surface properties and thus influence the efficiency of coal cleaning. In this work, the bulk and surface precipitation of the dissolved mineral species present in Pittsburgh No. 8 coal was investigated under controlled experimental conditions. Changes in the surface properties of coal due to the precipitation were monitored by following zeta potential. Solution potential data were used to elucidate the mechanism of the precipitation. The effect of the precipitation of the dissolved species on the floatability of coal was found to be marked.

Jan 1, 1995