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By John W. Rozelle, David S. Bolin

INTRODUCTION During the normal course of a mining project, a feasibility study will be prepared that addresses all the aspects of the project including geology and mineral inventories, mining and geo- technical, metallurgical processing, infrastructure, environmental considerations and economic analyses. These studies are prepared for various reasons. Occasionally, a feasibility study will be prepared solely for use within a company as justification for development expenditures, however, these documents are frequently submitted outside the company either to raise funds from financial institutions or from public financing on one of the various securities exchanges. Mineral industry consultants are often called upon to participate in the preparation of feasibility studies or to conduct an independent audit and review of an internally prepared study. As the recoverable mineral resources form the foundation upon which the balance of a feasibility study is based, including the economic analysis of the project, the resource aspect of the study is examined very carefully by financial and securities organizations. The balance of this discussion is directed toward the various geological and resource estimation aspects of feasibility studies that experience has shown to be of particular importance. Much of this discussion will be directed toward open pit gold operations, although the principles are applicable to any type of deposit. 2.0 GEOLOGIC RESPONSIBILITIES IN FEASIBILITY STUDIES The principal geological effort in the preparation of a feasibility study is generally dedicated to the following areas: - Preparation of Geologic Reserve/Resource Estimates - Condemnation of Sites for Facilities, Access Roads, Leach Pads, Waste Dumps and Tailings Disposal - Collection of Geotechnical Data - Provision of Mineralogical and Petrological Data Pertinent to Metallurgical Processing - Selection of Appropriate Bulk Sampling Sites for Collection of Metallurgical Samples Each of these items will be addressed in detail in the following sections. 3.0 RESERVE/RESOURCE ESTIMATION An ore reserve estimate consists of the determination of a volume, or tonnage, and a grade for the deposit. There are numerous cases in the mining industry of projects that have experienced severe difficulties when operational ore grade, tonnage or metallurgical amenability have proven to be deficient compared to predicted estimates. An error in estimation of tonnage generally leads to more long term problems affecting mine life and production schedules. However, a significant error in the estimation of grade, particularly if mined grade is lower than anticipated, can have an immediate, and often disastrous, effect upon a project. The geologic preparation leading to an ore reserve estimate generally follows a logical sequence familiar to

Jan 1, 1987

By V. K. Karra

An improvement in the present day screen sizing methods calls for knowledge on i) how material in the size range: 0.5 x 1.5 times the through-fall opening of the mesh on a deck, splits between the oversize and undersize streams of the deck, and ii) how near-mesh content of the feed affects the screening performance. In the throughput based sizing method given here, this is accomplished through the introduction of a generalized partition curve and a near-mesh factor. A newly developed efficiency factor is employed in addition to the traditional screen sizing factors.

Jan 1, 1979

By W. M. Snoddy

The Montana Tunnels diatreme is a low-grade polymetallic ore body containing economically mineable quantities of gold, silver, lead, and zinc. Widely varying gold grades combined with the general erratic nature of the mineralization create a complex sampling, assaying, and ore control problem. In order to maximize productivity and profitability, a variety of procedures have been used. These include differing sample size, frequency and method. In addition, assay techniques have been adjusted and refined to fit specific requirements, the result of which is an accurate, functional sampling and ore control system.

Jan 1, 1991

By L. R. Berry

The successful selection of a slurry pump depends on the accuracy and completeness of the information provided for the application. Inaccurate or incomplete information can result in incorrect pump selection and / or operational problems. Some information is more critical to the selection process than other information. A full description of the slurry (liquid -solid mixture) including the particle size distribution and maximum concentration, the flow, head and NPSH requirements are most important for successful slurry pump selection and operation. Common problems resulting from improper slurry pump selection will be discussed to illustrate the need for correct selection requirements.

Jan 1, 1996

By J. Peshel

This paper presents a regulatory perspective of the design and construction of the Exploratory Shaft Facility which may become part of the future high-level waste repository. Site characterization concerns and long-term waste isolation concerns require the consideration of various shaft design and construction aspects quite different from that of conventional shaft sinking.

Jan 1, 1989

By J. S. Peterson

The National Institute for Occupational Safety and Health (NIOSH), Pittsburgh Research Center (PRC), has conducted research to improve electrical fault detection on coal mine direct current (dc) trolley systems. Present circuit breaker protection systems are current-magnitude-based and cannot discern between normal traffic and high resistance electrical faults. Tests were conducted at cooperating mines to assist in developing a neural-network-based detection algorithm for distinguishing between electrical faults and normal operation. The Fast Fourier Transform of the trolley rectifier current signature served as baseline data for the neural network. During field tests, the algorithm performed with greater than 90% accuracy.

Jan 1, 1997

By Y. C. Kim

For the past quarter of century, much more effort and research have been expended in developing the "optimum" ultimate pit limit design algorithms and much less to solving the "optimum" open pit production sequencing. However, the potential economic benefit to an operating mine is far greater for the latter than the former. Unfortunately, the problem of "optimum" open-pit production sequencing has not been fully solved to date. This paper first reviews the past and currently used methodologies for developing this sequence. The staggered pit phase geometry problem of advanced stripping and operational constraints such as ore and waste tonnage requirements by period and necessary contiguity of mining faces are the main reasons why the "optimum" production sequencing problem has not been solved as yet. This paper also explains why any method which attempts to simplify the problem using ultimate pit limit design algorithm will fail to reach an "optimum" solution.

Jan 1, 1994

By Albert Ruiz

The 2,250-MW, coal-fired Navajo Generating Station located in Page, AZ draws water from Lake Powell using submersible pumps installed in five inclined shafts. Drought threatens to lower the reservoir to below the existing intakes. A system of new steel-lined intake shafts located on the same site was required for uninterrupted plant operation. The small size of the site, and the need to keep the existing system in operation, required detailed designs and placed significant limitations on construction equipment and activities. The Navajo Sandstone that forms the near vertical shoreline of the reservoir is 98 percent very fine grained quartz, highly abrasive and contains highly fractured intervals that presented numerous challenges to drilling the new 152-m (500-ft) deep, 109-cm (43-in.) diameter intake shafts inclined 23° to 26° from vertical. Spatial constraints, submersible pump design and operational criteria required that each shaft have a unique inclination and orientation and hit a small breakout target located 76 m (250 ft) under water. Sophisticated drilling equipment and techniques as well as state of the practice downhole survey technology and methods were used to make adjustments and maintain drilling accuracy with less than 1 percent deviation. Environmental requirements mandated water as the drilling fluid and grout was not allowed in to the lake under any circumstances. The shafts were videotaped and the breakout locations were examined using an underwater remotely operated vehicle (ROV) to verify shaft locations and rock conditions, and to guide placement of pneumatic packers to ensure grout did not transmit to the lake during the steel liner installation. In anticipation of the invasion of quagga mussels, the shaft design included an allowance for a chemical dosing system and a copper-rich alloy at the exposed portions of the steel liner.

Jan 1, 2011

This chapter contains the edited transcript of the "Gold Heap Leach Information Exchange" session that was held at the 1990 SME/AIME Annual Meeting in Salt Lake City, Utah. The exchange occurred on the afternoon of February 27, 1990. The session was intended to act as a forum for discussing some of the more prominent operating problems associated with heap leaching precious metals. The information exchange was very successful. The exchange consisted of several panelists introducing and discussing different topics, follow by a comment and question period. This transcript contains the panelists' presentations as well as comments and questions from the floor and the panel. Extraneous comments and remarks have been edited out. Some wording has been changed for clarity, but the transcript is basically an accurate account of what was said. At the end of the transcript are two papers submitted as part of the panel discussion

Jan 1, 1990

By Morgan M. Sears, Gamal Rashed, Michael M. Murphy, Brent Slaker

A parametric study was conducted using FLAC3D numerical models to examine the impact of oblique loading on the strength and yield pattern of a stone pillar using two simplified geometry types. In type-1 the side walls of the pillars were assumed to be perpendicular to the roof and the floor, while in type-2 the side walls were assumed to be vertical. These two geometries are frequently used to simplify/model the creation of pillars in dipping mines. Results from the numerical modeling indicate that dipping pillars have reduced strength compared to horizontal pillars, and they are at an elevated risk of failure. Also, an asymmetric failure propagation pattern could be obtained depending on the interaction between the pillar width/height (W/H) ratio, seam dip, in situ stresses and pillar geometry.

By Richard Gallagher, Russell K. McFarland

INTRODUCTION The Southern California Rapid Transit District has commenced Preliminary Engineering for an 18 mile Metro Rail Project. This initial line will consist of approximate 36 miles of single track tunnel and 16 subsurface stations. The estimated cost of $1.2 Billion in 1978 dollars, places it in the category of a major public works project. During the planning phase of this project, particular attention was paid to the National Academy of Science Reports, "Better Contracting for Underground Construction" (1974), "Better Management of Major Underground Construction Projects" (1978), and "Management of Urban Construction Programs" (1980). The improved transportation service that this project will furnish the Los Angeles Metropolitan Area will result in significant benefits that will add immensely to the economic well being of the community-which is one of Webster's definitions of improved productivity. RAPID TRANSIT PROJECT BACKGROUND Rapid Transit studies have been going c in the. Las Angeles area since 1925. In 1969 and 1974, sales tax ballot issues were not adopted by the electorate of the county mainly because the pre-ponderous of County voters are outside the City of Los Angeles.

Jan 1, 1981

By S. A. Abetel Sabour

In this work, the block theory was applied to determine the safe limit of the angle of face slope at Limestone quarry of Assiut cement company in order to decrease the occurrence of dangerous potential key blocks. Four joint sets were observed and measured at the face. Computer program based on the vector analysis technique was developed to determine the removable block codes. Stereographic projection was also used in this work to determine the removable block codes and to calculate the maximum limit for the angle of dip of the free face, which was found to be 77°.

Jan 1, 1998

By A. Pincomb

After determining minable acreage, tons are calculated by multiplying minable acreage by average thickness and by a volume-tonnage conversion factor. Converting from tons in the ground to tons sold across the scale takes fines and internally used and wasted stone into consideration, resulting in minimum losses of about 10% for limestone and 15% for sand and gravel. A high degree of certainty about thickness, lateral continuity and geologic character defines proven reserves. Assuming continuity of these characteristics defines probable reserves. By using tpa estimations and annual tonnage requirements, the life of a deposit can be quantified. The decision can then be made regarding the necessity of securing more acreage. Some landowners choose to multiply aggregate price, operating income, or a royalty rate by tons to arrive at a value for their reserves. In doing so they probably overstate the value of their land.

Jan 1, 2003

By Russell L. Wood

Introduction It is the morning after and there is one monumental hangover among many, if not most, of the oil companies that invested in mining in the past decade. How an oil company looks at mining depends on the time period. A few years back, around the time of investment, they were probably looking at a balance sheet of their own that was beginning to go wild. Many of their commodity prices already increased two-, three-, or fourfold, with no end in sight. There was a need to invest their earnings someplace before the stockholders or the government got too interested. And that someplace needed to be an industry where their own management skills could be applied. In mining there was an industry amazingly similar to their own. Both worked with nonrenewable natural resources, dealt with the same types of government agencies, and had the same type of critics and pressures from the general population. Oil executives saw mining as an industry that was somewhat backward as compared with their own. They also saw how a generous ration of the capital and management skills, so handsomely bestowed upon the oil industry, could be used to great advantage. But, looking at mining through the eyes of an oil company today, this is what might be seen: • An industry that has been spectacularly unprofitable for the past few years; • An industry of many commodities, any of which can go bad on short notice for protracted periods, for a variety of unpredictable and uncontrollable reasons, or for no reason at all; • A labor-intensive industry, often beset by labor problems. And with only limited potential for further economic mechanization or automation in today's primitive mining environment; • An industry confronted with external, foreign, and political problems, with no reasonable expectation of near-term relief; and • An industry that does not appear to have many "up" periods in its immediate future. And, there is little chance for either big, fast bucks or long periods of large, steady earnings. What Went Wrong? The visions of a few years back seemed as correct then as today's viewpoints seem to be now. What happened to change these views? What went wrong? The simplest and easiest answer is that if the economy was normal back then, nothing would have gone wrong. This is an easy answer but, unfortunately, probably incorrect. Let us take a broad overview. Certain events enabled and prompted oil companies to invest heavily in mining. These same events were major factors in precipitating the worldwide recession that has grievously injured mining and has brought those mining investments into disrepute. Taking a somewhat narrower, but still broad overview, the simi-

Jan 3, 1985

By E. J. Rorem

Rockfall and unstable rock slopes can be con-trolled by using steel wire-rope net systems as barriers or as slope draping. The chief advantage of such systems over rigid type barriers is the flexibility of wire rope netting. This flexibility and strength permits kinetic energy dissipation with low maintenance requirements. Mining activities can produce temporary or long-term unnatural slopes and unstable rock faces that may produce rockfall hazards. Such conditions can necessitate efforts to minimize the hazard to workers, structures and equipment.

Jan 1, 1996

By Y. A. Attia, M. Elzeky

The effects of bacterial adaptation and partial replacement of leaching solution on the rate and extent of bioleaching reactions of a complex sulfidic gold ore were investigated. The ore was first concentrated by bulk sulfide, flotation, and the sulfide concentrate was treated by bioleaching using Thiobacillus ferrooxidans. The residues from bioleaching were treated by cyanidation to extract the gold and silver. Bacterial adaptation before bioleaching significantly increased the rate and extent of bioleaching reactions. Similarly, the daily partial replacement of leaching liquor enhanced to a great extent the leaching rate, and in some cases, increases of up to ten fold were observed. Both bacterial adaptation and solution replacement increased the gold recovery by about 2-fold and that of silver by about 1.3-fold. In this work, more than 95% of the gold and more than 98% of the silver could be recovered from the sulfidic gold ore when bioleaching was used ahead of cyanidation, compared with 18.3% and 52.3% by direct cyanidation.

Jan 1, 1992

In late 1993, Inco Ltd. completed a $600-million environmental improvement project at its Sudbury, Ontario operations -the largest single environmental project ever undertaken by a Canadian corporation. Efficient new facilities and innovative technologies installed during the course of the project have also significantly improved Inco's productivity and competitiveness. In early May 1994, a panel of 18 Inco authors contributed to a Technical Forum, "Environmental Programs at Sudbury," presented at the 96th Annual General Meeting of the Canadian Institute of Mining, Metallurgy and Petroleum (CIM) in Toronto. Their papers have been published in CIM's Toronto `94 Proceedings Volume, pp. 62-77. The following report draws primarily on discussions of Inco's milling and smelting operations published in the Proceedings Volume. The Proceedings Volume also includes papers on the acid and oxygen plants and on engineering, construction and commissioning of the project. The 222-page Proceedings Volume is available from CIM, $C27 plus shipping. To order, contact: V. Ward, CIM, Xerox Tower, 1210-3400 de Maisonneuve Blvd W, Montreal, Quebec, Canada H3Z 3B8; phone 514-939-2710, fax 514-939-2714. Lane White, Publisher.

Jan 1, 1994

By Ali Kazmi, Wern-ping N. Chen

A load rating procedure was performed to evaluate safe load capacity of the Port of Miami Tunnel (POMT), FDOT Tunnel No. 871071 SR 887. The rating procedure performed on a total of eleven stations beneath roadways and with fill depth less than the tunnel exterior diameter (42 ft). Calculations on tunnel sections passing beneath roadways were performed to evaluate the structural response of the sections subject to moving vehicular loads, dead load, and earth pressures. Ratings were performed in accordance with AASHTO and FDOT guidelines. The procedure considered two types of vehicles (HL-93 and FL-120) and two rating levels (Design level and Permit level). As part of HL-93 vehicle, Tandem load was also considered for rating, separately. For HL-93 and HL-93 Tandem, inventory and operating level ratings were performed. The results show rating factors are high. The minimum rating factor is 16.8 using Inventory truck HL-93. For Permit level using FDOT FL-120 truck the minimum rating factor is 6.9. As can be seen, rating factors are higher than comparable analysis for bridges. This paper explains how the procedure can be implemented for tunnels and evaluates the rating results.

Dec 1, 2022

By M. R. Bowie, J. M. Barker, J. S. Hingtgen

Techniques of testing perlite require a combination of art and science. The modifications made to the perlite Corp. vertical laboratory furnace include addition of instrumentation, flowmeters, vibrators, automatic feeders, and regulators. The basic testing sequence consists of expanded density, furnace yield, compacted density, percent sinkers, and compaction resistance. These tests are modified versions of those specified by the Perlite Institute. This sequence is designed as a preliminary evaluation of a material's suitability for horticultural-aggregate end uses rather than a detailed measure of filtration capability.

Jan 1, 1988

By S. R. Abt, J. D. Nelson, G. M. Smith

An empirical investigation was conducted to formulate a design criteria for predicting the beach profile of hydraulically deposited tailings. Field data were obtained from mining operations producing gold sulfides, silver, molybdenum, copper, platinum, and uranium. Site-specific parameters were collected that included the beach slopes, tailings soil properties, slurry properties, and the slurry distribution system characteristics. Each of the beach profiles were dimensionlessly plotted, and regression expressions were computed. It was determined that either a power expression or exponential expression closely predicted each beach slope. A general power expression and a general exponential ex¬pression were developed resulting in a design criteria. A procedure was formulated to determine which expression, power or exponential, is applicable to any specific site. A slope designation chart was developed as a function of the discharge, the tailings critical tractive shear stress, and the inertial forces exerted by the slurry on the beach.

Jan 1, 1987