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By P. E. Sperry, J. M. Duncan

INTRODUCTION The purpose of the report on which this paper is based is (1) to evaluate the potential for cost reduction of urban mass transit tunnels by use of alternative materials transport systems during the tunneling process, and (2) to identify research and development program elements to assure that the materials transport system will not become the limiting factor for the rate of excavation. The approach taken was: Review the state of the art of urban tunneling by extensive interviews with representatives of tunnel contractors, equipment manufacturers, government agencies and consultants, and by review of recent literature.

Jan 1, 1979

By M. C. Rockwell, G. F. T. Lay

Promising placer gold exploration sites offshore Lunenburg County are drowned pre- and post-glacial river channels and auriferous glacial tills. Gold values up to 5.67 9/m3 have been encountered in the vicinity of the Ovens Peninsula offshore Lunenburg County. Moderate gold values associated with notable amounts of heavy minerals were reported from various other exploration sites in this area. This paper highlights the major geological and gemorphological features for placer gold depositions in southern Nova Scotia. The past to present gold exploration activities nearshore and offshore Lunenburg County are summarized and potential areas for placer gold identified.

Jan 1, 1988

By C. B. Manula

A method for the feasibility assessment of open-pit operations using conventional shovel/ truck systems to mine steeply pitched coal seams has been applied at The Pennsylvania State University. Three computer models were developed for the analysis: a geology and reserves model (GEOL), an open-pit materials handling simulator (OPMHS), and a cash flow model (CASH) (Manula, Albert, and Burgos, 1976). GEOL provides the basic mining data; OPMHS simulates shovel/truck performance related to pit profiles and average mining locations to provide productivity rates needed to size the system; and CASH provides either a selling price or rate of return (ROR) for the product. The general flow of information generated by these models is shown in Fig. 1. Since the ratio of overburden-extracted to coal-produced places a definite economic limit upon a mining venture, geological data must be analyzed with the least possible manual effort to minimize computational errors. This is especially true if the property contains several seams that are steeply pitched. In this situation, a computerized analysis is by far the most efficient and effective method to determine coal reserves and waste tonnage. This chapter describes the reserve model developed at Penn State and provides an example to demonstrate its application.

Jan 1, 1979

By G. T. Adel, W. Z. Choi

In previous work at Virginia Tech, a population balance-model describing the simultaneous processes of size reduction and mineral liberation has been developed. Experimental verification of this model, however, has been limited to a binary mineral system containing only one composite particle class. When considering multiple classes of composite particles, estimation of model parameters becomes much more difficult. In the present work, a procedure for estimating model parameters for a multiple-composite- class model has been developed. Emphasis is placed on direct experimental determination of these parameters. The physical significance of the breakage rate function and the liberation function in characterizing the liberation process is also discussed.

Jan 1, 1987

By R. K. Mehta, G. T. Adel

A review of the literature reveals that methods for simulating the coupled behavior of size reduction and liberation are limited to binary mineral systems containing one composite particle class. The aim of this paper is to describe the development of a mathematical model to simulate such behavior for binary and ternary systems containing multiple classes of composite particles. A modified Levenberg-Marquardt algorithm and a finite difference Jacobian are used in conjunction with the developed model and a set of constrained equations to estimate all kinetic parameters. This estimation scheme is validated far a binary ore (sphalerite-dolomite) with five composite particle classes using experimental data.

Jan 1, 1991

By J. E. Rourke, O&apos

This paper describes the use of rock index property testing to obtain rock properties that a.re useful in the design and construction planning of an underground development for civil engineering or mining projects. The index properties discussed include (1) point load; (2) Schmidt hammer hardness; (3) abrasion hardness; and (4) total hardness. The first two index properties correlate to uniaxial compressive strength and Young's modulus. Discussions are given on the relationship to rock mass properties and the integrated use with semi-empirical, geotechnical design methods. The latter two properties correlate to construction performance parameters and some experience is cited. Examples of data are presented from an index testing program carried out on siltstone, sandstone and limestone rock core samples from a deep borehole drilled in the Paradox Basin of Utah for a nuclear waste repository site investigation.

Jan 1, 1988

By S. Frimpong, N. Demirel

Overburden excavation is an integral component of the surface mine production chain. The walking dragline is the most economic production equipment for overburden excavation in strip mining. Draglines are capital intensive, and thus, investments in multiple units severely impact the economic viability of projects. The use of few dragline units results in highly concentrated production focus, which must be efficiently managed to derive the potential economic benefits. Efficient use of draglines requires a thorough knowledge of the powered functions, the 3D rotational and translational motions and machine-formation interactions within the operating environment. Dragline kinematics and dynamics are required to understand and characterize machine performance and efficiency. In order to sustain the high productivity in difficult operating conditions, the dynamics of the dragline must be modeled and analyzed based on comprehensive kinematics. This paper investigates the planar kinematics of the front-end assembly and its interactions with the formation during excavation using the “Vector Loop Analysis” formulation with comprehensive simulation modeling in MATLAB Simulink. The kinematic models are used to examine the translational, rotational and angular displacement, velocity and acceleration components of the dragline front-end assembly along defined bucket trajectories during excavation. The results are the precursors for comprehensive modeling to examine the load deformation, torque requirements and dragline stress loading profiles for improving machine health and longevity.

Jan 1, 2006

By H. E. Goetzman

A cooperative research project supported by the taconite industry and the Minnesota DNR was undertaken to establish quality standards for carboxymethyl cellulose (CMC) based organic binders. The objective of this study was to identify the effect of CMC quality parameters such as degree of substitution, molecular weight, and purity as well as the effect of inorganic extenders such as sodium carbonate on performance. These factors have been evaluated by green-ball testing with two taconite concentrates followed by pot-grate tests. Balling tests with bentonite and Peridur were conducted to provide baseline data. At a constant DS the molecular weight as measured by viscosity had the greatest effect on green-ball drop strength. Dry-ball compression strength was most dependent on CMC addition rate and sodium carbonate content. DS was not found to have a major effect on green-ball quality for medium molecular weight CMC.

Jan 1, 1988

By John W. Conn, Harry C. Verakis

An explosion in an underground coal mine can have a devastating effect on the main fans used to provide mechanical ventilation. The Code of Federal Regulations, Title 30, Part 75.310 (CFR, 1992), specifies that each main mine fan shall be offset by at least 15 feet (4.6 m) from the nearest side of the mine opening unless an alternative method of protecting the fan is approved in the ventilation plan. Also, each main mine fan shall be protected by one or more weak walls or explosion doors. This paper presents venting and fan configuration designs which provide a comparable degree of safety for explosion protection. Design flexibility is enhanced and a means for consistency in safety judgements is afforded.

Jan 1, 1993

By Alan P. Cook

Methane levels have been measured around continuous miners and compared with computer simulations of methane flow. A multi-channel data logger, reading continuously from six methanometers, has shown methane levels to vary at different positions around a continuous miner, with the cutting drum and the immediate face area not necessarily recording the highest concentrations. Methane levels in the driver's cabin are generally low compared with the return side. Computer simulations, using computational fluid dynamics, have been supported by the measured data, and have shown that methane behaviour within the first few metres of the face varies considerably for different bord and pillar development stages. Methane is diluted rapidly to acceptable levels, but the distance required for this is extended when ventilation flow to the face is restricted.

Jan 1, 1995

By E. K. H. Goh

A reliability-based engineering design approach for the effective design of reshaped spoil dumps was developed with the aim of obtaining structurally reliable spoil dumps at optimum reshaping costs. The aim was also to satisfy environmental erosion standards and community expectations. This approach encompasses the linking up of three major components: erosion appraisal of spoil dump designs, reliability-based engineering design of spoil dumps and costing of spoil dump reshaping practices. This paper addresses the application of the reliability-based engineering- design approach to the assessment of spoil dump designs for erosion control. Included are various types of erosion prediction models and reliability-based engineering-design analytical techniques. Also included is a case study that demonstrates the application of this approach.

Jan 1, 2000

By Wei Wu

A computer-aided method for optimization of bench blast design in surface mines is presented. The design procedures basically consist of two steps. Firstly, a series of normalized, full- scale bench crater tests must be carried out in the field to find the optimum burden that produces the largest amount of acceptable fragments and other parameters that defines the effective fracture zone. Next, the locations and initiation sequence of blast-holes will be determined in such a way that each hole, at its time of firing, will be responsible for same amount of burden rock and will be in a position favorable to effective fracture of burden rock. A computer software "B.B." which can assist the second step of the design is fully introduced and its application is illustrated by an example.

Jan 1, 1992

By A. R. Zambrano

Equations for power draft, capacity and work input for predicting the performance of industrial grinding mills are derived based on torque measurements using a laboratory instrumented mill. These derivations are based on mechanical principles and on the first-order kinetics of the grinding process. Rittinger's, Kick's and Bond's laws express work input as work index (Wi) times a particle size function. It is proposed that these laws are only particular cases of more general expressions having the particle size function raised to an exponent, i.e., the work exponent (We). Case studies illustrate the excellent prediction of the Wi - We models compared to the three mentioned laws, and, from the data, the corresponding general mill-sizing equation is derived. Key words: Grinding mills, Comminution, Work index, Mill sizing

Jan 1, 2003

By W. M. Schafer, C. F. Luckay, D. A. King

Monitoring devices have been installed at several mine sites to assess the potential for the development of acid rock drainage (ARD) in waste rock, spent ore and tailings material. In addition, instrumentation has been designed for monitoring changes in water quality in pit lakes. These devices monitor temperature, oxygen, water movement and water chemistry in the waste rock pile. This information can be used to evaluate the current and future ARD risks and the effectiveness of caps and covers. The information can also be used in the design of other reclamation strategies that limit ARD development. The instrumentation includes nested thermistors and oxygen sensing ports, neutron access tubes, heat dissipation units (HDUs) and lysimeters. Many of the monitoring devices can be linked to a data logger and telemetry systems, enabling monitoring data to be downloaded from the office.

Jan 1, 1999

By Ian McFeat-Smith, Robert J. Fowell

Roadheader machines have a specific place in modern tunnelling, not simply as a compromise between drill and blast techniques and full face machines, but as an economic and versatile form of mechanised tunnelling where the method of excavation is easily integrated with tunnelling operations. In the past, roadheaders have been subjected to misuses by engineers who failed to realise that, as in all mechanised tunnelling, a planned and systematic approach is essential if the full potential of these machines is to be gained. An increasing awareness of this, together with the introduction of the more powerful roadheader carrying their cutting potential into the hard range of rock is changing this situation and now makes the prospect of using roadheaders particularly attractive (1). The advantages gained by employing these machines can be considerable and Table 1 lists some of them. This table illustrates that from both cost, and installation points of view, the roadheader has considerable benefits over the full face machine. However, the principal advantage gained is in broken ground where heavy supports can be installed immediately at the tunnel face. In addition, access for planned maintenance and repairs to most working parts of the machine is at a premium and average machine utilisations of 40 - 60% can be expected. In comparison to drill and blast methods, up to 40% better progress can be regularly achieved, and the subsequent savings in overbreak costs alone would more than pay for the cost of a roadheader used to drive a 3km long tunnel. As with full face machines, ground disturbance is minimal and for short tunnels in urban areas a road-

Jan 1, 1979

By Victor F. Hollister

Porphyry copper deposits can be categorized into three models for purposes of prospect evaluation: Breccia-pipe, modified Lowell and Guilbert, and diorite models. The modified Lowell and Guilbert model is normally associated with a quartz-bearing intrusive and a potassic, phyllic, argillic, and propylitic alteration sequence. Variations can occur in the alteration zones of this model that range from orthoclase-rich (Kalamazoo, Silver Bell, and Mineral Park) to ortho- clase-deficient (Petaquilla and Bougainville) potassic zones. The unifying features of the model are the presence of a phyllic zone and a quartz-bearing intrusion. The breccia-pipe model (Toquepala) is characterized by structure and alteration related to or controlled by breccia. Where tourmaline occurs in the breccia, the identity of the model is usually clear. However, if tourmaline is not commonly developed in the breccia (La Caridad), the deposit can be misidentified as to model. Porphyry copper deposits associated with quartz-deficient intrusives, whether these are calc-alkalic diorites or alkalic plutons, are characterized by alteration suites distinct from those of the modified Lowell and Guilbert model. These have been generalized as diorite model porphyry deposits. Because alteration and mineralogical development in diorite model deposits is distinct from that of the modified Lowell and Guilbert, ore guides and exploration tactics differ for the two models. The reprint that follows describing the three prospecting models summarizes their features. It is to be emphasized that these are models used in exploration for specific deposit types and are not genetic, tectonic, or geographic models. Porphyry copper deposits can be metamorphosed. Gibralter is an example of a Lowell and Guilbert model deposit that has undergone regional metamorphism.

Jan 1, 1991

By L. Korkiala-Tanttu, M. Rinne, Z. Song

Disposal of mine tailings has been recognized as an unavoidable burden of mining companies and local authorities. Conventional methods dispose mine tailings in a passive manner which hardly generates any value from them. On the other hand, growing local communities close to mines need more infrastructures which require great amounts of raw materials. In view of the above mentioned situation, a novel utilization of mine tailings is explored as alternative material for asphalt pavement, in order to extract more value from mine tailings and solve the high cost of pavement material. Inherent physical properties of the mine tailings were first investigated to find out their availability as pavement material. Then test specimens were made as mixture of the mine tailings and other pavement material to be tested in laboratory. The mine tailing materials presented a considerable potential as asphalt filler for low-volume roads. Furthermore, the limitat

Jan 1, 2011

By R. M. Bowen

To help solve problems associated with the optimization of complex coal preparation systems, a mathematical model has been assembled which can simplify calculations pertaining to the core of the plant, i.e. the coal cleaning section. It uses algebraic expressions, derived by fitting hyperbolic equations to Mayer curves, to calculate optimum settings for a specified array of coal cleaning units and feeds. This is done without search procedures, and with usually only minor iteration of a simple calculation to specify optima within 0.02% of specified product ash contents. The key to the calculation is a relationship derived via the analytical geometry of conic sections facilitating easy application of the incremental ash theory of separations. The model has been assembled in a generalised form to cater for N processes in parallel, each giving M separations to produce P final products. Examples are given involving assessment of some complex circuit options.

Jan 1, 1986

Mine managers need useful data to support production and maintenance decisions; for example, to evaluate the performance of replacement components. Today, managers rely solely on past experience, supervisors, opinions, and time studies. Our paper describes the concepts and algorithms we are developing for an automatic, intelligent decision support system (IDSS) that will aid managers by reducing and analyzing large amounts of, monitoring system sensor data and report only key production and maintenance information.. IDSS contains a pattern recognition, subsystem (IDSS/PRS) prototype to report graphical trends in traditional time study elements. We are designing. and prototyping a knowledge representation subsystem, using Knowledge Craft Tools, that will learn and adapt to the dynamic mine environment and reason about the recognized patterns using representations of manager's knowledge, equipment, capabilities, and mine layout and operating procedures. This subsystem will reduce, large quantities of time study type information to key issues that interest different managers.

Jan 1, 1989

By Stefan Norgaard

In today's modern gold mining industry in Australia, and the world, more and more companies are recognising the competi­tive advantages gained by implementing an effective training program for operations (processing plant) personnel. Plant operators, or process technicians, are unique amongst all other gold mine employees. They are at work in shifts cov­ering 24 hours a day and their actions can have a profound effect on the operation's economic performance. To a large degree, the minute to minute decisions and actions of an operator can deter­mine whether gold is extracted to bullion in the goldroom or is discharged into the tailings dam. Experience has suggested that most small to medium sized gold operations in Australia, and even some large ones, have not implemented an effective training program. This is not attrib­uted to deliberate negligence or "anti" attitudes against training, moreover mill superintendents and metallurgy managers are technical people not oriented to human resource techniques. Usually the demands of designing, constructing and commis­sioning a gold plant overshadow the need for training in the first instance, In fact some well designed plants treating friendly oxide friable ore have little need for a dynamic well trained oper­ating staff. However, many plants do require a thinking team to optimise production and changing ore conditions towards the end of a mine's life can expose poor competence levels at large expense. Few managers will argue that training is a necessity and results in a win-win situation. The operators win by increased job skills, job satisfaction, clear career development and possibly better pay conditions. Trained personnel usually reciprocate with increased effmt and work ethic. The company wins also by having a thinking team which will maximise gold production and reduce operating costs.

Jan 1, 1998