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By N. R. Billette

In 1982 and 1983, a study was undertaken to analyse the applicability of Elbrond?s analytical model to suit the needs of Lake Asbestos of Quebec in their computerized open pit planning and scheduling strategy. The immediate goal was the assessment of the optimal allocation of trucks and the determination of the extra cost of in-pit blending. Data from 45 tonne trucks was used to estimate the mine capacity based on a fixed assignment policy. The tonnage yielded by the analytical model was compared with the results of a simulation program. Another point that the study high- lighted was the definition of efficiency parameters for the haulage system: shovels-trucks-crusher. The efficiency, both of the utilization of financial resources and of the operations, for the overall system reaches optimal values in very precise conditions for the number of pieces of equipment in operation. Such a parameter is proposed as a standard for the definition of an optimal number of trucks and shovels in operation. Deviations from this optimum do occur in a well-planned system for qualitative goals. These can then be quantified in terms of costs to the mining company.

Jan 1, 1986

By F. F. Aplan

The material known as coal has a highly variable composition. As a consequence, coals show a great variation in their physical and chemical properties as a function of coal rank. The situation is further complicated because the preparation engineer must deal with raw coal, as mined. This is an assemblage of coal, upwards of 30% mineral matter and, typically, several percent pyrite. The kind and amount of the mineral constituents is also highly variable from source to source. A knowledge of coal rank and source location, and the kind and amount of associated impurities, is the first step in evaluating the response of a raw coal to preparation procedures. The raw coal must first be characterized before information from one source can be extrapolated to that of another.

Jan 1, 1988

By M. Karmis

Surface subsidence has been recognized as an inevitable consequence of underground coal mining for several centuries. The damage resulting from this phenomenon has been witnessed in rural as well as in urban areas and ranges from simple land settlement to severe structural damage to buildings. Subsidence prevention is not feasible, at least under the existing technological and economic constraints of underground coal mining. Using a rational method of subsidence prediction, it has been demonstrated in many coalfields that subsidence control can be successfully practiced in order to reduce and accommodate subsidence within environmentally acceptable levels. This paper presents the development and testing of a subsidence model, based on the zone area method. This technique is a refined development of the influence functions and it is capable of investigating a mining plan of any shape, thus facilitating both longwall and room-and-pillar mining systems. More specifically, this study can be divided into two major efforts: (a) The development of the zone area model. This formulation was designed to accommodate the analysis of an optimum number of zones, over the area of interest, both accurately and efficiently. (b) The testing of the computer techniques with appropriate field measurements. In order to accomplish this, published as well as unpublished information was collected and analyzed according to a regionalized scheme. This procedure minimized differences in subsidence characteristics between the various coalfields and allowed a regional validation of the predictive capabilities of the model.

Jan 1, 1982

By Lynn B. Hales, Randy A. Yncbausti, Rick Smith

Object oriented programming has been developed to model the way we think about the world. It allows higher levels of abstraction, generalization and classification than many other programming techniques. Some tools of object oriented design and programming are encapsulation, classes, inheritance, modularity and reusability. Expert systems have been used for years to implement process control strategies in the minerals industry. Expert systems allow process control knowledge to be expressed in linguistic rules that are processed by an inference engine. Expert systems which employ object oriented design and programming provide new opportunities for real- time process control. The concepts of object oriented programming and an example object oriented expert system are discussed in this paper.

Jan 1, 1992

By Roderick G. Eggert, John E. Tilton

During much of the 1970s and 1980s, world metal consumption grew more slowly than during the 19505 and 1960s. The slowdown contributed to surplus capacity and low real prices because actual consumption was consistently less than expected as new mining and mineral processing capacity came on stream. Over the last year or so, however, world metal consumption has picked up noticeably, raising the question, Has metal demand returned to the long-run growth rates more typical of the 1950s and 1960s than of the 1970s and 1980s? This paper examines this possibility and, more generally, assesses the factors that will shape demand for the major metals over the longer term. TRENDS IN METAL CONSUMPTION The extent to which metal consumption has recaptured the brisk growth rates typical of the 1950s, 1960s, and early 1970s is shown in Figure 1. This figure traces the consumption of crude steel, primary aluminum, refined copper, refined lead, and refined zinc between 1960 and 1987 for the western world, consisting of the OECD countries (including the United States), and the developing countries. Consumption increased in 1987 for all five metals, and preliminary data for the first six months of 1988 suggest even more substantial increases, at least for the United States (U.S. Bureau of Mines, 1988). However, Figure 1 also shows that the recent increases in consumption are not untypical of similar surges during earlier periods of economic expansion and thus may reflect only cyclical or temporary factors. In short, the available data are unable to provide a clear indication of whether recent increases in metal consumption reflect the beginning of a new era of faster growth or simply a cyclical and temporary upturn associated with the expansionary phase of the business cycle. Consequently, to pursue this issue, we are forced to examine the underlying forces that will shape metal demand trends over the next decade. The approach we have taken involves two steps. The first examines the prospects for overall economic growth. The expectation is, the faster the economy expands, the faster the production of metal-containing goods grows.2

Jan 1, 1989

By J. F. T. Agapito, C. E. Brechtel, C. J. Gilbert, T. R. Kelly, R. C. Karlson

A multi-lift benching cut-and-fill mining method was adopted at Asamera Minerals (U. S.), Inc.'s Cannon Mine to balance the goals of high productivity and near 100 percent recovery with the need to minimize subsidence. High strength backfill was required to provide effective long-term overburden support and safe working conditions during the pillar recovery operations. Operational designs were evaluated using numerical modeling to predict global mine stability and backfill strength requirements. These models incorporated sequential mining of primary stopes, backfilling of primary stopes and recovery of pillars, and have been transferred to the mine operations group for use in evaluating different production sequences. The modeling has provided a better understanding of the structural response of the mine to excavation of the primary stopes and removal of the pillars. Predictions about the transfer of overburden weight to the abutments, pillars and cemented fill pillars have provided a criterion to evaluate mining plans and production sequence. Comparison of these predictions with actual mine structural performance has developed confidence in the design of the mining method and in the geomechanical design methods being employed. Primary mining of the B-North zone is nearly complete, and the stopes have been generally stable, as projected in the original design. Some exceptions have occurred where locally stope pillars have failed due to the presence of adversely oriented sheared beds. Recovery of the pillars between the

Jan 1, 1987

By K. C. Carriere

INTRODUCTION The purpose of this paper is to introduce the reader to basic control strategies for solid/liquid separation in mineral processing and to indicate some of the implementation difficulties to be encountered, without becoming overly involved in details of process, equipment or software. It is assumed that the reader has some familiarity with control systems and with dewatering processes, since exploration of these topics would require considerably more length. The paper is organized into three parts: first a general discussion on the need for control of dewatering processes and of the general criteria involved, next a more detailed elaboration on control strategies for the various unit operations, and finally a case study showing a specific approach towards such a project. Motivation & Objectives The justification for implementing any control system in an industrial plant is to improve operations and thereby to increase profitability. Without this motivation, the system will likely be perceived as unnecessary and will decline into disuse, an expensive and troublesome monument to someone's ill-conceived ideas. However, when a control strategy is correctly conceived, implemented and integrated into operations, it can provide significant advantages in operating ease and efficiency, and a handsome return on investment. In general terms, the objectives in establishing a control system are: • stabilization of process disturbances maintenance of product quality • maximization of throughput • dearer definition of process • protection of personnel and equipment A successful control strategy must address at least some of the above criteria. However, the most important requirement is a commitment on the part of plant personnel and management to start up, operate and maintain the system, and to upgrade it to reflect current process status and operational philosophy. Process Applications In this paper, control strategies will be explored for the most common methods of dewatering of mineral pulps. These unit operations include: drying, centrifuging, filtering and sedimentation. While the first three are important, they do not tend to be as complex as sedimentation, and thus will not be as exhaustively treated. Sedimentation is very widely applied, not

Jan 1, 1986

By R. J. Sweigard, R. V. Ramani

Estimated costs and revenues can be used in evaluating postmining land use alternatives. However, postmining land use decisions have to be made in an environment complicated by several additional factors. These factors, including cultural, natural, and managerial issues, are not as easily quantified as costs and revenues but may be more important determinants. There fore, some approach is needed to attach relative weight to the various factors. The concept of fuzzy sets assembled into a structured hierarchy facilitates analysis of the relative value of individual factors and their impact on each alternative under consideration. In this paper, a method is presented that employs fuzzy set analysis to evaluate postmining land use plans on the basis of these nonquantitative factors.

Jan 1, 1988

By Andrzej Frycz

The development of the theory of reliability creates more and more possibilities of its application in different domains of technics. The methods evolved to date, both theoretical analysis of the engineering systems and investigations techniques in practice can be put in use a d translated from one science to another one [1,3,7J . It needs to consider the specific of the different sciences. But it is necessary to take account of the specific characteristic of each line of science. The reliability investigations needs, justified in technical and economical viewpoint appear too in mine ventilation technics and systems. The mine ventilation system is a complex of workings and ventilation plants, which serve to supply the networks with a sufficient quantity of fresh air from the atmosphere and then carry off the vitiated air. The condition necessary for a ventilation system to perform definite task is the correctness of all its elements, that is a capability to preserve in a expected range of tolerance, the values of basic parameters. The element of a system which ceases to work correctly is called failed. The basic parameter of all elements of a ventilation system is the characteristic curve, pressure loss - air quantity relation ?p = f(Q) (1) This curve concerning the workings and ventilation stoppings is given by the formula: ?p = R Q2 (2) thus the resistance R (of the workings or stoppings) may be taken as a characteristic parameter. The course of this characteristic f(Q) will be given in a complex form in concern with fans, ejectors, air curtains. The failure of a ventilation plant or working is therefore an event, relying on a change of its characteristic, thus for a definite time the losses of the plant's or working's capability set in for the fulfilment of its function in the ventilation system. The failures are divided in viewpoint of their nature on sudden and progressive. We are in concern with the sudden failures which are characterised by a violent change of the ventilation element parameter for example a fall of roof, or silt up of the working, opening or failure of the ventilation stopping, the stand-off of the fan or ejector etc. We distinguish two kinds of failures on the viewpoint of their action on the air flow: the "opening" failure and "closure" failure. The prevalence of factors, which causes the failures is in connection with the intersection in the mine of roads of haulage, roads of underground transport of materials and lining elements, roads of people motion with airways, as also depends on the rock pressure reaction on the workings lining and plants placed there. Other factors will yet be decisive upon supply decay of fans, ejectors and curtains. The appearance of failure of the ventilation element is therefore of random nature and determines the change of the element, when it is passing from operating state to unoperate. Qualifying the ventilation system element to one of these states is easy, when the characteristic change is clear and occurs suddenly, that was assumed. The investigations conducted by Patrushev and Karnaukh [91 in concern with the ventilation stoppings resistance change in the case of their opening, had shown the possibility of resistance value change in the range of several hundreds higher.

Jan 1, 1980

By R. W. Draves

Planning and testing in advance of the mining operation are essential. This advance work can involve physical and chemical analysis of overburden cores, field test plots, green- house studies or any of a multitude of other baseline data collection activities. This paper presents the results of Central and South West's field test plots and how they relate to topsoil substitution. Besides the obvious need for testing in advance of mining, there are the inevitable regulatory requirements. Quoting from the office of Surface Mining Regulations concerning topsoil substitution: 216.22(e) TOPSOIL SUBSTITUTE AND SUPPLEMENTS -Selected overburden materials may be substituted for or used as a supplement to topsoil if the office determines that the resulting soil medium is equal to or more suitable for sustaining revegetation than is the available topsoil and the substitute material is the best available to support revegetation.

Jan 1, 1985

By Stephen D. Schwochow

Aggregate producers nationwide well recognize the numerous problems often faced in securing local approval to open and operate new gravel pits and rock quarries. Similar problems are faced in Colorado, but this region also presents certain political, social, and geological complexities that have become particularly troublesome in the last 10 years. The gravity of the local permitting dilemma can be related directly to the worsening supply-demand imbalance for aggregates in the state's most populated area, the Front Range urban corridor, particularly the Denver metropolitan area. The drive to develop crushed-rock reserves to supplement dwindling alluvial supplies and to meet increasing regional growth demands was somewhat predictable but perhaps more a "last resort" alternative forced onto producers by a hesitant and often apathetic government.

Jan 1, 1982

By Gerald P. Kelton

Hydrocyclones have emerged as successful classification devices In closed circuit grinding applications However, their use for ultrafine particles separation is a relatively new application For ultrafine particles separation In small diameter (51 mm or smaller) cyclones, the cyclone diameter, feed pulp density or viscosity, pressure drop, and configuration play an important role Most often commercial application of the small diameter cyclones suffers from plugging problems resulting from the presence of fibres, wood chips, paper scraps, etc This paper describes important design features of small cyclones, followed by examples of case studies of commercial application of these cyclones

Jan 1, 1983

By Yanmin Wang, Eric Forssberg

This paper presents recent experimental results in wet ultra-fine grinding and classification of industrial minerals carbonates and kaolin clays using a stirred ball mill and a high performance centrifuge. The studies have been focused on the effect of beads (size, density and load) on the grinding efficiency. The use of chemical additives for the control of slurry rheology in the stirred ball milling is presented. The role of pre-crushing with a high-pressure roller mill on subsequent ultra-fine grinding is discussed for energy saving and size reduction. The use of a disc-stack nozzle centrifuge for ultra-fine classification duties at high solids contents is presented.

Jan 1, 1998

By H. Dho

Two aromatic-type chelating agents, 1,10 phenanthroline (phen) and 8-quinolinol (quin), were tested as specific depressants for magnetite in the cationic silica flotation of magnetic taconite concentrates. Micro and batch flotation tests, along with zeta potential and adsorption measurements were used. In the presence of a cationic collector, dodecylammonium chloride (DAC), the Fe/phen surface chelate electro-statically repelled DAC, and magnetite was depressed. The negatively charged Fe(quin)2(OH)2-on the magnetite surface attracted the cationic collector and made magnetite floatable.

Jan 1, 1995

By A. C. Noble, D. E. Ranta, J. W. Mustard

Skarn deposits present many unique problems in estimating ore reserves, including difficulties arising from the complex character of the mineralization and intricate ore body shapes resulting from structural complexity. Mineralization within skarns occurs in metasomatically altered carbonate horizons produced by magmatic hydrothermal fluids emanating from intrusive stocks. Deposit formation is controlled by both the presence of favorable host rocks and by proximity of these host rocks to a mineralizing intrusion. Ore controls must be defined to account for abrupt changes in grade that occur between miner- alized and unmineralized horizons. Gradational grade changes within the mineralized zones must also be defined in terms of skarn type and included barren rock to assist in reserve estimation. Defining mineralized limits can be further complicated by faulted, rotated, or folded strata affecting the morphology of an ore body. The MacTung copper-tungsten exoskarn deposit, located along the Yukon-Northwest Territories border in Northwestern Canada exhibits a number of unique properties that preclude a simple mathematical approach to ore re- serve estimation. This deposit is used to demonstrate methods for modeling geologic controls and geostatistical properties for a skarn deposit.

Jan 1, 1992

By J. W. Cooksley

Seismic methods provide an efficient and comprehensive approach to overburden studies pertinent to mining exploration and development, and to other mining and civil engineering problems such as rock mechanics, slope stability, and foundation engineering. For the purpose of defining geologic units and structural features, these methods are generally regarded as the most accurate, but most expensive, of the commonly-used geophysical exploration methods. Although the accuracy and cost of seismic work are generally affected adversely by rugged topography and complicated geologic conditions, it is in rough terrain and complex geology that seismic methods offer important advantages in overburden investigations. For example, to find the surface of rock underlying unconsolidated overburden at depths of approximately 200 feet, a 50-foot spacing of drill holes along the profile line would be required to yield a degree of resolution and accuracy similar to that obtained from a 50-foot spacing between seismic detectors along the same line. See Figure 1. In cases similar to that shown in Figure 1, a twelve-channel recording seismic system would be used. The main components of such a system would be: 1. detectors (commonly referred to as geophones) which convert the ground movement resulting from seismic waves into an electrical signal. 2. a multi-conductor cable which connects the seismic detectors to the amplifiers. 3. ampliiiers, amplify and filter the electrical signals . 4. oscillograph, records the amplified signal. 5. the blaster and firing line. A typical layout of the seismic spread and the components of the system Is shown in Figure 2.

Jan 1, 1968

By James C. Burrows, Frances Kramer Mesher

Tungsten-containing ores are mined on all continents of the world. China is the world's largest producer and controls the world's largest reserves. The USSR, itself a sizeable producer, is estimated to be the world's largest consumer. The major use for tungsten in the noncommunist world is in production of cemented tungsten carbides for cutting, drilling, and wear parts. Other major uses include lamp wires, steels for tools, and armaments. Real tungsten prices have been in a general decline since 1977-1979 as the tungsten market undergoes basic and lasting structural changes.

Jan 1, 1986

By J. Willison

Over the past decade, the coal mining industry has faced the difficult task of remaining profitable in the midst of declining market prices. Historically, the industry has been quite capable of meeting this challenge by various means. As total costs to mine and market coal continue to increase, new methods of tackling the problem must be implemented. Studies have shown that although many options exist to influence both inby and outby costs, the greatest potential remains in addressing costs at the coal face. Mining operations can positively effect a change in their profitability by either reducing costs, or by increasing production to in turn lower their net cost per man-hour. Original equipment manufacturers can play a key role in both options through the introduction of new technology that permits higher extraction rates, as well as other advantages leading to lower cost coal. A leading advancement over the past 30 – 40 year period has been the advent of progressively higher voltages to operate the mining equipment. This advance enables higher power transmission for a given cable size, operation at lower amperages resulting in less voltage fluctuation, and reduced heat on the cable and electrical components.

Jan 1, 2003

By K. A. Natarajan, J. M. Modak

A review of published literature on the biosorption of metals using nonliving biomass is presented. Factors such as pH, temperature, initial metal concentration, biomass loading, the presence of co-ions and the pretreatment of biomass influence the metal uptake by biomass. Although few generalizations are possible, unified theories regarding the mechanism of uptake are not available. Therefore, the above aspects of metal biosorption have to be defined individually for each biomass and metal-ion pair.

Jan 1, 1996

By Fulian He, Jianhang Chen, Shoubao Zhang

"Fully grouted rock bolts have been used in mining industry for many years. Significant research has been conducted to evaluate the load transfer behavior of fully grouted rock bolts with experimental programs. However, compared with that, less work has been conducted with analytical modelling. Therefore, in this paper, the authors used an analytical model to study the load transfer behavior of fully grouted rock bolts. To confirm the credibility of this analytical model, an in-situ pull-out test was used to validate this model. There was a close match between the experimental result and the analytical result. Following this, a parametric study was conducted with this analytical model. The influence of coefficients, Young’s modulus of the rock bolt and the diameter of the rock bolt on the load transfer performance of rock bolts were studied. Furthermore, the load distribution along the fully grouted rock bolt was analytically studied. The results show that the axial load in the rock bolt decayed from the loaded end to the free end independent of the pull-out load. However, the trend of the load distribution curve was influenced by the pull-out load. This paper was beneficial to better understand the load transfer mechanism of fully grouted rock bolts.INTRODUCTIONRock bolts have been used in the mining industry for a long time. They are used as the reinforcement tendons to keep the stability of openings in underground mining and the slope in open-pit mining. Furthermore, rock bolts are commonly used not only in the mining engineering, but also in civil engineering (Thompson, Villaescusa, and Windsor, 2012).The rock bolt is a tendon which can be a rod or a cable inserted into a borehole drilled in rock masses or soils. Traditionally, the material of rock bolts was steel. However, engineering practices showed that the steel rock bolts can be easily corroded by the moist environment in underground mines. Next, Fiber Reinforced Polymer (FRP) was used to manufacture rock bolts, which are termed as FRP rock bolts. Experimental results proved that the FRP rock bolts can effectively reinforce the surrounding rock masses without being corroded (Wang et al., 2018)."

Jan 1, 2019