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By Jr. Neudecker

Rock melting technology can provide in-situ glass liners in nuclear waste package emplacement holes to reduce permeability and increase borehole stability. Reduction of permeability would reduce the time and probability of groundwater contacting the waste packages. In-creasing the stability of the storage boreholes would enhance the retrievability of the nuclear waste packages. The rock melting hole forming technology has already been tested in volcanic tuff similar to the geology at the proposed nuclear waste repository at Yucca Mountain, Nevada.

Jan 1, 1989

Relatively lower recoveries (60%) of coarse phosphate (-16 +35 mesh) particles are attributed to the difficulty in transportation of coarse particles from the pulp to the froth column and rapid drainage of these particles from the froth column to the pulp. Increasing the hydrophobicity of coarse particles by higher, more efficient coating of the collector and using larger froth volumes have been suggested to overcome these problems. In this study, the role of emulsification of the fatty acid-fuel oil collector on the flotation recovery of coarse particles was examined. It was determined that emulsification can not only increase the coarse particle recovery, but do so at higher fractions of fuel oil in the collector, thereby reducing the reagent cost as well.

Jan 1, 1989

By D. L. Johnson

A number of small but rich copper sulfide (chalcocite) ore deposits are located on Michigan's Keweenaw Peninsula. These deposits are considered too small to warrant the capital investment required for conventional mining. However, they are being considered for in-situ solution mining as a way to revitalize the area's once prosperous copper extraction industry. Geology, mineralogy and geohydrology of the deposits have been investigated to determine their suitability for leaching; Three conclusions were drawn from the work. First, the sulfide mineralization is found primarily in fractures (65%) and, therefore, is accessible to injected leach solutions. Second, the ores are shallow, occurring from surface exposure to about 200 meters depth; injection and recovery wells would not have to be excessively deep. Third, the rock was found to have low permeability, in the neighborhood of thirty millidarcys or less. However, preliminary hydraulic fracturing experiments indicate that this will be an effective method for permeability enhancement. In one experiment a permeability increase of 100 times was achieved using a very low injection pressure at shallow depth. Additionally, fracture aperture spacings measured from drill core were correlated with fair success to field permeabilities.

Jan 1, 1989

By Y. J. Wang

Along with the inexpensive availability of computing hardware, a proliferation of powerful personal computers is being realized throughout the mining industry. People from every arena within the industry are designing, developing, and/or applying mining specific software, which is increasing at a rapid rate. In this section applications (or potential applications) that are being made in the analysis and design of mine systems are discussed, including the design of compressed air networks, the simulation of hoisting operations, analysis of longwall face maintenance, and a summary of computer and software applications for analysis and design of coal operations. In "Computer Aided Design of Mine Compressed Air Networks" the authors describe software, called CompAir, and the underlying theoretical and mathematical foundations of it that can be used to make accurate, cost-effective designs of compressed air systems for mines. It includes algorithms for network analysis and the optimization of pipe diameters. The techniques embodied in the software replace traditional rule-of-thumb approximations which have been used in the past and avoid the operating problems that often result from using average, steady-state parameter values, estimated for ideal operating conditions. CompAir, coded in Turbo Pascal for personal computer use, bases calculations on compressible fluid theory, which gives more accurate results than incompressible fluid theory whenever high flow rates or long line distances are involved. The net- work and pipe diameter analysis is formulated as a nonlinear programming problem. The solution technique requires a trial and error approach that iteratively applies the unconstrained optimal pipe diameter algorithm to successive solutions of the constrained network problem until the diameters become "fixed." The authors conclude by recommending the use of a mine-wide monitoring system to improve cost control and provide a better understanding of flow regimes in compressed air networks.

Jan 1, 1989

By Uday Kumar

This paper presents details of an availability study for a fleet of diesel engine operated load-haul-dump (LHD) machines used in a Swedish mine. For the purpose of this study, the LHD machines have been considered as a system comprised of many subsystems like engine, brake, transmission, etc., in series. As availability is dependent on both the reliability and maintainability characteristics of the system, together with reliability, the concepts of maintainability are also discussed. The need for exploring the data for the presence of any structure, which is very common in repairable system data sets, is emphasized with suitable examples. Simple graphical techniques are used for verifying the independent and identically distributed (IID) assumption for the data set. The error introduced due to the use of the exponential distribution in place of more appropriate distributions in estimation of availability and reliability characteristics is analysed.

Jan 1, 1989

By E. Fahrenkrog

An intelligent supervisor developed using expert system tools and applied to a crushing plant is presented in this paper. The structure of this supervisor, based on a model of a human operator, consists of a Knowledge base containing a qualitative model of the process, and a Rules base with the heuristic logic used by an operator when supervising a plant. The simulation results obtained show the potential of this type of systems to supervise the automatic operation of a plant.

Jan 1, 1989

By Vljay K. Chhipa

Artificial intelligence is" an emerging technology in the field of computer application. Expert system have been developed to imitate human intelligence and reasoning process. Expert systems have much scope of application in the decision making process in mineral exploration as such decisions are highly subjective and expert opinions are very helpful. This paper presents a small expert system to analyze reasoning process in exploring for uranium deposits in sandstone.

Jan 1, 1989

By J. Brent Hiskey, Srini Raghavan

The physical chemistry of dissolution of silicate and complex oxide ores in aqueous lixiviants has been reviewed. Particular attention has been paid to the analysis of dissolution mechanisms and kinetic models and to the elucidation of the role of the porous nature of the materials on dissolution behavior. Importance of the physico-chemical characteristics of the leach residues on leaching efficiency has been discussed.

Jan 1, 1989

By C. J. Lewis

Commercial lime plants in the United States and Canada are depicted in Figure 1. The sources of lime available to Nevada and bordering states are rather few. Chemstar Lime has plants at Apex, Nevada and Nelsen, Arizona. Continental Lime, Inc. has plants at Tacoma, Washington, Townsend, Montana and Delta, Utah. However, Continental Lime has a new rotary kiln installation underway near Wendover, Nevada. This plant is scheduled to come on stream in the fall of 1989.

Jan 1, 1989

By Hans von Michaelis

Gold metallurgy has advanced remarkably over the last decade. Even more significant progress will be made over the next five years, particularly in the application of advanced comminution techniques and control, preconcentration (flotation, ore sorting and coal gold agglomeration), enhancement of cyanide leaching technology, non- cyanide leaching, treatment of refractory ores and concentrates, and improved recovery systems. Carbon adsorption processes have become standard practice for ores with relatively high gold/silver ratios, but ion exchange potentially offers distinct advantages and has recently been demonstrated to perform better in at least one application. Even in the established zinc precipitation and CIP processes several important practical improvements are emerging as experience is gained at the ever increasing number of operating plants. Improved process control and reduction of reagent consumption costs are two important goals of industry at this time.

Jan 1, 1989

By Z. Eisenstein, H. Heinz

INTRODUCTION Contemporary underground transit systems often require cross sections which are not adaptable to shield tunnelling. Due to the frequently large dimensions of these cross sections, which are normally situated at shallow depths and in soft ground, full face advance is not feasible because of ground control and construction requirements. Ground deformation and face stability are controlled by "staged excavation", which consists of sequentially driving smaller, specially arranged, individual headings hence avoiding full-face excavation. Shotcrete is normally used for initial support and these tunnels are frequently described as applications of the New Austrian Tunnelling Method (NATM). Figure 1 illustrates the relative size of large cross section tunnels with respect to conventional shield tunnels. Within the scope of this paper, 'large' cross sections are defined as those whose continuous (i.e., without intermediate pillar support) cross sectional excavated area exceeds 60m2. This definition includes most double track highway, railway and subway tunnels, subway stations and some single track railway tunnels. Excavation schemes which have been more frequently used for continuous cross sections (i.e., with no intermediate pillars) are presented in Figure 2. This classification is an extension of that presented previously by Eisenstein et al. (1986). The symbols used for classifying the excavation schemes are formed by the letter T (for "type"), followed by a number, which represents the number of excavation stages fully embraced by a shotcrete ring, termed "cells" by Lessmann (1986). The numbers inside the cross sections in

Jan 1, 1989

By Daniel J. Turk, William R. Banning, John Paterson, Thomas J. Weitz, Michael L. Clark

Introduction Pegasus Gold's Montana Tunnels mine is a large surface gold, silver, lead, and zinc mine located 37 km (23 miles) south of Helena in southwestern Montana. Milling operations commenced in late March 1987. The concentrator achieved full production in May that year after undergo¬ing several modifications and improvements. Production for 1988 is projected to be 2.48 t ,80,000 oz) of gold, 34.2 t (1.1 million oz) of silver, along with 8.5 kt (9400 st) of lead, and 22.6 kt (25,000 st) of zinc from lead and zinc concentrates. Mill throughput currently averages 11.7 kt/d (12,900 stpd), compared to the origi¬nally designed capacity of 11.3 kt/d (12,500 stpd). Cash production costs, net of bypro¬duct revenues for the third quarter 1988, were below $3.20/g ($100 per oz). The introduction of ore to the concen¬trator marked the culmination of 12 years ex¬ploration, evaluation, and development. Initial milling operations encountered diffi¬culties with the circuit as designed. As a result, several modifications and improve¬ments were made to the plant. This article is intended to assist other companies developing projects of this type and complexity. It discusses the mine's de¬velopment from feasibility and construction through start-up. The operation, as it exists today, is reviewed including the modifica¬tions and improvements made since start-up. History The mine is situated in Jefferson County, MT within the historic Corbin-Wickes min¬ing district. Underground mining began in 1864 and flourished until the early 1900s. Between 1864 and 1900 the vein deposits in the district produced about $41 million dol¬lars worth of lead and silver ores containing subordinate amounts of zinc, copper, and gold. At various times, three smelters were operated in the area.

Jan 1, 1989

By R. R. Tatiya

The algorithms to model three stoping methods - sublevel, down- the-hole (DTH) and cut and fill stoping have been developed. These algorithms are capable of designing and performing economic analysis for one or more number of stopes in a continuous orebody. The design and economic analysis of each individual stope are first obtained. This is followed by the composite stope design layout and overall economics of the stopes under study. This paper describes only the stope design aspects of these models. The programs have been written using Fortran 77 with Tektronix graphical aids available at Imperial College Computer Centre (ICCC) London and are based on the basic data obtained from Khetri Copper Complex (KCC) and Rajpura Dariba (a zinc mine) in India. Minor modifications, however, may be necessary in some routines when used on other systems and for other mines.

Jan 1, 1989

By A. M. Stone

Following the conceptual idea of a Continuous Elution Process early in 1982, the system was successfully pilot plant tested at Western Mining's Kambalda gold plant in December 1982. As a consequence of these tests the Ok Tedi elution ciruit design was changed from batch operation to continuous operation resulting in a reduction in the number of similarly sized elution columns from five operating with one standby to one operating with one standby and halving the process steam requirements. In addition to providing significant capital and operating cost savings the continuous process was simpler to operate than the batch process.

Jan 1, 1989

By Donald S. Clarke

The Umuna epithermal precious metal deposit has provided the target for a simulated rock geochemistry exploration program, directed at bedrock exposed in the drainage system of eastern Misima Island. A geochemical halo to the deposit is readily recognised in the mafic meta-volcanic country rock. This halo is defined by anomalous results for both major (K, Na, Ca, Mg) and minor (Au, As, Sb, Cu, Pb, Zn, Ba, Rb, Sr, Cs, Bi, Ga, S) element geochemistry, extending further than 1km from the deposit. Such halos are sufficiently extensive to provide adequate exploration targets in the search for epithermal mineralisation, complementing mineralogic and secondary media geochemical investigations.

Jan 1, 1989

By Angelus S. C. Owili-Eger

The protection of groundwater resources is a growing issue on both the legislative front and within the private sector. At present, the legislative push is to establish within the Environmental Protection Agency a comprehensive research, development, and demonstration program relating to groundwater contamination and resources. It is evident that certain aspects of such legislation will be directed at the mining industry. Consequently, the mining industry must position itself to address the issues and concerns from a backdrop of facts and knowledge by developing an integrated hydrogeochemical model of the mining environment.

Jan 1, 1989

By L. T. Larson

Nothing in Turkey is simple. Its his¬tory is long and convoluted, its culture fascinating, its metallogeny diverse, and its geology very complex. This article will focus on the geology of western Anatolia and the precious metals poten¬tial of this third of Turkey. Any gold produced by mines in Tur¬key since the early 1900s has been a by-product of the mining for other met¬als, such as copper from the massive sulfide deposits of the Pontics. Archaeological records, however, prove that gold was mined from the Pactolus (present day Gediz) River and refined by Croesus at Sardis in about 550 BC. Other records and legends make it possible that gold was mined before 1200 BC for the Homeric City of Troy (Priams treasure?) about 25 km (15 miles) east of Canakkale at Mad¬endag and Kartaldag. A final legend of antiquity suggesting gold in what is now Turkey relates to King Midas. And, indeed, the city-state belonging to a king of that name has been recognized near the city of Eskise¬hir. More recently, precious metals have been mined at Madendag-Kartaldag in the late 1800s. Arapdag, near Izmir, remains the only "authenticated" epith¬ermal precious metal deposit in Turkey (Mosier et al., 1985). With this spotty record, why the sud¬den interest shown by at least five Euro¬pean-based, three or four US-based, and several other international mining firms and their Turkish subsidiaries? Like other aspects of Turkey, the complete answer is not simple but, reduced to its basics, has three parts. Turkey, relative to many developing nations, has a stable, democratic form of government (although it also has a for¬midable bureaucracy) whose currency exchange rate is premised on the US dollar. New laws promulgated since 1983 have opened the country and welcomed foreign investment. Some have even provided investment incentives. The Mining Law of August 1985 made sweeping reforms of the old land tenure system. This law made it possible for a foreign-based company to have a wholly-owned Turkish subsidiary en¬gaged in mining. Equally important is the belated recognition that western Anatolia, while geologically compli¬cated, is today basically a province Neogene extensional tectonics having many of the geologic attributes of the leading gold producing province of the US - the Basin and the Range. Geologic rationale for precious metals exploration Tectonic/lithologic framework: Alle¬gorically and simplistically, Anatolia during early Neogene (middle Miocene) can be likened to a tube of toothpaste with the cap off. It is squeezed in the vise formed by the Arabian plate mi¬grating north toward the southwest end of a stable Asian platform. The "tube" was compressed. It could not expand to the east because it was sealed by what is now southern Russia and Iran. The filling of the tube escaped to the west, in the direction in which the cap was miss¬ing (Fig. 1). So developed during the middle to late Miocene the western-most struc¬tural province of Anatolia. This was done by a process aptly termed tectonic "escape" by Sengor et al (1985). This province is dominated by exten¬sional tectonics much like the Basin and Range of the western US and has an estimated extension of between 30% and 50%. The most striking manifesta¬tion of this extension is the 10 to 11 major east-west trending grabens (Ge¬diz, Buyuk Mendares, Kocuk Mendares, etc.) and intervening horsts, although a much greater number of smaller, gener¬ally northeast-striking grabens and half

Jan 1, 1989

By P. T. Luckie

More efficient classification with a single hydrocyclone through equipment and/or operating design changes does not appear possible. However, improvement in classification efficiency by increasing the sharpness index and decreasing the apparent by-passing while changing the cut size is possible through proper staging of inefficient hydrocyclones. But feasible multistaging requires achieving the necessary material balances around the units. Because of the interactions among the units, these balances require extensive iterations. The final step before commerical installation should be a laboratory demonstration, in order to define the control algorithm required to maintain stability. However, eventually a sufficient knowledge base should be developed that will permit simulation in place of laboratory testing as well as the incorporation of a feed forward strategy.

Jan 1, 1989

By John E. Urosek, Herman Schade

In March, 1988, a fire occurred in a large underground coal mine. Coal Mine Safety and Health of the Mine Safety and Health Administration was immediately notified of the situation. They requested the assistance of the Pittsburgh Health Technology Center (PHTC) to provide monitoring and analysis of the mine atmosphere in and around the fire area to insure the safety of the miners escaping from the mine and for the miners involved in extinguishing the fire. The capability to provide this type assistance is maintained by the PHTC Offices located at 4800 Forbes Avenue, Pittsburgh, Pennsylvania. The equipment used is maintained field ready and can be mobilized almost immediately. This paper will discuss the response to this recent major mine fire.

Jan 1, 1989

By K. H. Bettles

The Goldstrike Mine is in Eureka County, Nevada, approximately 23 miles northwest of the town of Carlin. The mine is at the north end of the Tuscarora Spur of the Tuscarora mountains at elevations of 5,300 feet to 5,950 feet. It is part of the Bluestar/Goldstrike subdistrict of the Carlin Trend of sediment hosted, disseminated gold deposits. The Carlin trend comprises over 15 major gold deposits with production, reserves and geological resources of approximately 50 million ounces of gold (Fig. 1). In the Bluestar/Goldstrike subdistrict, there are four major deposits; Post, Betze, Bluestar, and Genesis, plus numerous smaller deposits (Fig. 2). Betze is located on property controlled by Barrick Goldstrike Mines; Bluestar and Genesis on Newmont Gold property; and Post on both Barrick and Newmont property.

Jan 1, 1989