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By Jean-Michel Rendu

Equipment capital operating costs represent a significant portion of the total cost of most mining operations, and a variety of computerized methods have been developed to assist in the selection and effective use of this equipment. The questions to be answered and the tools available to answer these questions vary with the type of mine to be analyzed, the stage of development of the mining venture, the size of the operation, the details required, and the technical or economic objectives to be reached. Even though a majority of publications are directed towards open pit mining operations, the underground environment is not neglected. In the early planning stages of a mining venture, equipment selection is the problem to be solved. The simplest computer systems are designed to' automate time consuming manual tasks. A data base is supplied to and maintained by the user, which describes the technical and economic characteristics of available equipment. The user specifies the physical environment within which the equipment will be used and chooses from the data base a combination of loading and transport equipment. The role of the computer is to detemine the production which will be likely reached, the associated costs, and other relevant statistics. This approach is most helpful when modeling small operations or isolated parts of larger operations.

Jan 1, 1989

By S. I. Nozhko, V. N. Guliy, A. A. Zolotarev, L. M. Luyshnia

The study of the apatite deposits of the Aldan Shield shows wide spread of the Precambrian apatite-carbonate ores and possibilities of using them for extraction of apatite. Dependency of flotation on ore minerals was studied according to the following scheme: preparation of the monomineralic samples of anhydrite, gypsum, chlorite, serpentine, phlogopite, apatite; mixing them in apatite ore of the average composition; followed by flotation. Another series of the experiments was conducted to ascertain a dependence of flotation activity of the different minerals on the different flotation reagents, which were used as collectors. It has been shown that apatite from silicate-carbonate ores is most extractable because it has the biggest size of grains and is the most free of inclusions. Beneficiation of the sulphate-containing apatite-carbonate rocks is possible when flotol - 7.9 is used as a collector. Meanwhile, the use of the tallaktam leads to an increase in the sulphate recovery. The estimation of individual technological features of the layered Mghydrosilicates and their influence on the process of beneficiation has been examined using samples of apatite-dolomite ore (P205-8%) with the addition of the phlogopite, serpentine and chlorite. The results show that there is little influence of the chlorite presence on the flotation while the serpentine presence leads to a decrease of the flotation, because of its high specific surface area.

Jan 1, 1993

By L. L. Gagné

The Churchill Falls Development will eventually be the largest source of hydroelectric power in North America. Churchill Falls was discovered in 1839, but until recent years it was not practical to begin development of this site to tap the 7 million horsepower available. This $1 billion project is located in Labrador, 700 miles northeast of Montreal and 650 miles northwest of St. Johns, Nfld. The construction will divert the Churchill River 5 miles upstream from the 245 foot Churchill Falls. Rapids above and below the Falls, together with the Falls proper, give a natural head of 1,040 feet. In contrast to the basic simplicity of the surface installations, the powerhouse labyrinth is astounding in size and complexity. The largest in the world, it consists of three major chambers - the powerhouse, 972 feet long by 81 feet wide and 154 feet high; the surge chamber, 763 feet long, 40 feet to 64 feet wide and 148 feet high; and the transformer gallery, 856 feet long by 50 feet wide and 39 feet high. Other major features include eleven inclined penstocks, each 1200 feet long and 20 feet in finished diameter; eleven draft tubes averaging 37 feet in finished diameter and 162 feet long; six vertical cable shafts each an average of 865 feet in length; a series of eleven short bus tunnels linking the powerhouse and the transformer gallery; a vertical power-

Jan 1, 1997

By R. S. C. Rogers

Semiautogenous milling was the subject of 18 papers presented at the SME Fall Meeting in Albuquerque, NM. The process design and scale-up of SAG mills was discussed in several papers. These included a review of testing methods for the sizing of SAG mills by Barrett and Allan. Austin et al. presented an improved simulation model for SAG mill grinding, with model validity demonstrated against pilot plant SAG mill test results. Rogovin et al. presented some pilot plant results relating to the charge motion, hold-up, and particle size segregation in SAG mills. A number of papers described improvements achieved in operating SAG mill circuits. These included presentations by Dailey concerning mills at the National Steel Pellet Co., by Brown and Pipke concerning the Island Copper grinding circuit, by Lovering of Afton Mines Ltd., and by Bartrum et al. of Kidston Gold Mines Ltd. Bush and Hegerle of Amax also discussed SAG mill operations at the company's Henderson mill. They addressed the topics of SAG mill grinding economics. Other papers addressed the topics of SAG mill control (Vanderbeek et al. and Pennington), grinding media (Meulendyke et al.), liners (Kjos), and fabrication (Carr and Utley). The 1985 AIME Annual Meeting in New York featured four technical sessions concerning size reduction technology and practice. Papers involving fundamentals included one by Hinde describing simulation model usage for quantifying the classification and concentration of heavy minerals in grinding circuits. Another, by Rogers et al., discussed simulation models that were used as a design aid in evaluating screens versus hydrocyclones for fine grinding circuits. Arbiter discussed dimensional considerations in grinding mill design, and Schwechten and Schonert proposed the use of a high pressure roll mill as a means for reducing energy requirements in fine grinding. Internal classification in tumbling mills was the subject of a paper by Hogg and Rogovin. The mechanism of internal classification were identified and their effects illustrated. Simulation for the process design of ball mills was exemplified in a paper by Rogers, Austin, and Brame concerning phosphate grinding in laboratory to large diameter mills. The incorporation of liberation into size reduction models was the subject of papers by Austin et al., Herbst et al., and Choi et al. Gupta used simulations models to further investigate zero order fines production in ball and rod mills. Of the published literature, many articles on size reduction were published in various publications in 1985. Articles concerning ball mill grinding included an analysis of interstitial gas effects in dry grinding by Cottaar et al., an analysis of mill grinding noise by Watson, studies of factors affecting breakage rates in dry milling by Gupta et al., and in wet milling by Tangsathitkuchai and Austin. Austin and Klimpel presented two papers concerning ball wear and ball size distribution effects. Koka et al., and Gotsis et al., described recent developments concerning the Szego mill. A model for hammer milling circuits was described in papers by Gotsis et al. and Gotsis and Austin. Heim et al. reported on wet grinding in Perl mills, and Kuga et al. presented findings concerning pulverizing in a screen mill. Studies of grinding effects on particle surfaces were published by Meloy and Hofmann et al., and Scieszka proposed a technique to investigate pulverizing properties of coals. Austin and Rogers discussed factors of powder technology of significance in industrial size reduction in mills and crushers. (Space limitations preclude listing of references. A complete list is available from author.)

Jan 5, 1986

By Kenneth L. Rubow, Virgil A. Marple, Ye Tao

Techniques are being developed for measuring the mass concentration of respirable diesel exhaust particles found in underground coal mines. Studies have been conducted over the past five years to investigate size selective sampling techniques to measure the respirable mass concentrations of diesel exhaust and mine dust aerosol particles in underground coal mines. Results from these studies have been used to develop design and performance criteria for a personal diesel exhaust aerosol sampler. Three personal diesel exhaust aerosol samplers have subsequently been designed and evaluated in both laboratory and field settings. These samplers use size selective classifiers for the determination of the respirable mass concentrations of mineral dust and diesel exhaust particles. Their designs are based on the premise that diesel exhaust particles are predominantly less than 0.8µm while mineral dust is greater than 0.8 µm. One design, selected for field evaluation, consists of a 10 mm nylon respirable dust cyclone followed by a 0.8 µm cutpoint impactor and afterfilter. The cyclone removes the large nonrespirable particles while the inertial impactor stage, collects the mineral dust on an impaction plate and allows the diesel particles to penetrate to an afterfilter. The two sample fractions of the respirable particles (<0.8 µm and >0.8 µm) are gravimetrically analyzed to determine the concentrations of the diesel and mineral dust portions in the respirable coal mine aerosol.

Jan 1, 1991

By Joseph P. Sobanski, Michael P. Bruen

The North Branch tunnel segment of the Tunnel and Reservoir Plan Mainstream System consists of 14,075 m (45,885 ft) of 9.2 m (30.2 ft) finished diameter and985 m (3,232 ft) of 2.5 m (8.25 ft) finished diameter concrete lined rock tunnels. The TBM mining and concrete lining methods used in completing this $166million project differed from “typical” TARP construction methods in that a two-stage concrete lining was placed and the lining was initially placed concurrently with TBM mining as a two pass system in the same tunnel segment. For the main tunnel (9.85 m diameter), TBM mining averaged 24 m/day (79 ft/day), excluding downtime associated with two main bearing changes, and the concrete lining placement, averaged 117 m/day (380 ft/day) and 53 m/day (174 ft/day) for the invert and arch segments, respectively.

Jan 1, 1999

By Paul D. Tomlingson

Part one of this two-part series covers conceptualizing and developing a maintenance information system. It explains what information is necessary to manage such a system. Next month, part two will discuss using this type of system with administrative information, including error and absentee reports as well as open work files. Introduction There is no doubt that quality, timely, and accurate information can make a solid contribution to maintenance cost reduction objectives. Yet, despite obvious benefits, methods being used to acquire information systems are proving costly, frustrating, and often unsuccessful. Those needing the information are disappointed. Mine managers, hoping to reduce costs with quality information, are instead seeing no system, no savings, and massive spending on information endeavors of questionable benefit. Options Any software vendor will happily sell you his program. Numerous mining organizations, having "gone to the cleaners" themselves, will gladly make their programs available to help cover huge trial and error development costs. Any package can only be a generalization. Any program bought from some other organization must undergo numerous modifications to make it work properly. In the process the initial cost is doubled. Many mining maintenance organizations do not know how to go about the task of conceptualizing, developing, installing, and effectively using a maintenance management information system. Consequently, many have hedged their primary responsibility of specifying what information they want, how they will get it, and how they will use it effectively. Into this void have jumped many who claim they can help. But some may not understand the special information needs of maintenance in the mining industry. By default, the whole scene of maintenance information systems has become confused and in need of clarification. A Starting Point Four broad phases are used to organize the steps by which maintenance acquires an effective maintenance management information system and initiates its use. Conceptualization is an identification of needs, factors that influence development, and an assessment of support for the system. Development is a plan of action for bringing the conceptualized information system to life. Consideration is given to the practical aspects of collecting field data, processing it, and converting it into useful information. Implementation consists of those actions by which the newly developed system is integrated into the organization and put in the hands of its personnel so that its value can be derived. Use addresses the means by which personnel use the information to accomplish maintenance improvement objectives. These phases are preceded by establishing the need for the information system. They are followed by a requirement to measure its success (Fig. 1). Conceptualizing the Information System Responsibilities - The information system user must acquire the system best suited for its use. A step-by-step process is essential to avoid many serious problems than can easily occur. The most important step is to clearly identify its objectives and lay out a course of action to achieve those objectives. The major reason for the failure to achieve information objectives is not carrying out this responsibility. Maintenance cannot delegate the task to data processing. It can obtain technical assistance but it must retain responsibility. Nor can maintenance purchase

Jan 7, 1985

By Hyung-woo Kim, Sup Hong, Sung-Soo Kim, Chang-Ho Lee

A deep-seabed integrated mining system, which consists of four subsystems such as riser pipe, buffer, flexible riser, and tracked vehicles, is presented in Figure 1. In order to collect more manganese nodules, multiple tracked vehicle systems should be used in a deep-seabed integrated mining system.

Sep 1, 2014

By R. J. Matetic

The Bureau of Mines, as part of a program to improve mine planning and development, is currently investigating the effects of pillar load transfer, which can impact mining operations within a multiple-seam configuration. A comparative study was performed at two separate mine sites to determine the effects of this load transfer mechanism. The Bureau installed and monitored instrumentation at both sites to gather pertinent data on rock mechanics. At mine site A overburden depth varied dramatically in the vicinity of the study area and reached a topographic high at the study site: inner burden thickness was less than a pillar width (40 to 45 ft) (12 to 14 m): floor heaving was experienced in both coalbeds where sandstone and/or shale floor units were observed: overlays of the mine layouts show pillars were not totally super-positioned: a maximum of 5 in (13 cm) of roof to floor convergence was measured and pressure readings indicated pillar core loading only and increased to a maximum of 7,000 psig (48,300 kPa) over instrument setting pressure.

Jan 1, 1989

By S. S. Hsieh

As part of a program to address the long-term need to ensure adequate supplies of domestic phosphate raw materials, the Tennessee Valley Authority (TVA) has conducted considerable research on dolomitic phosphate rock beneficiation. The discovery that alkyl diphosphonic acids act as phosphate mineral depressants led to the development of several processes involving a carbonate flotation step for the effective beneficiation of these problem ores. Most recently, a partial deoiling process in which the reagent consumption is greatly reduced has been developed. The reduction is achieved because part of the initial feed is beneficiated without passing through the separate carbonate flotation step. Using this method, a phosphate product containing 30.6-30.9% P2O5 and 0.7-0.8% MgO was obtained from a Florida dolomitic phosphate pebble that contained about 23% P2O5 and 2.0% MgO. The P205 recovery was 80.8-86.5%.

Jan 1, 1991

By P. H. Williams

Experiences gained using computers in the mining and geological environment have shown that it is quite rare for a system or the data it stores to be truly stand alone. Just as the mining enterprise aims to have a smooth integration of operations from exploration through mining and extraction to sales, so it should develop all its information systems within an overall framework or architecture which covers the applications and data as well as the computer hardware and communications. This paper discusses methods of achieving such an architecture, and describes some of the benefits it can have on the development and implementation of information systems. The key aspects are the identification of the business functions and the data that they use, and ensuring that the IS plan supports the overall objectives of the enterprise. Hardware and communications policies should be based on the plans for the applications and data, rather than the reverse.

Jan 1, 1986

By Ivor Hawkes, Malcolm Mellor

INTRODUCTION There are currently around fifteen companies in the United States and Europe manufacturing hard rock tunneling machines. In recent years upwards of 200 hard rock tunnels of lengths up to 12 miles and diameters to the order of 30 ft have and are being successfully driven by over 100 different machines. It has been predicted that within the next decade over 2,000 miles of tunnels will be driven for transportation purposes in the United States alone (OECD Advisory Conference on Tunneling, Washington, 1970) and it is expected that eventually most tunnels including mine drivages will be excavated by machines. All tunneling machines have certain common basic functions; thrust is applied to drive or hold the rock cutting tools into the face, and torque is applied to rotate the cutting tools over the face so that they can continuously break out rock. The speed of head rotation, together with the torque requirement, determines the cutter head power. (The power required to push the head forward is usually negligible.) There are many factors which determine how successfully a given tunneling machine will perform in a given rock but one of the most important is effective utilization of cutter head power. This paper is a review of the specifications and performance of hard rock tunneling machines, obtained from manufacturers&apos; catalogs, published literature, talks with manufacturers and visits to operating machines throughout the United States and Europe.

Jan 1, 1997

By Paul M. Keyser

Flotation columns continue to offer improved metallurgical and economic advantages over other flotation methods. Pilot testing at Ozark-Mahoning Co. in Rosiclare, IL led to installation of one 2.3-m-diam (7.5-ft-diam) column for zinc roughing and one 1.1-m-diam (3.5-ft-diam) column for zinc cleaning. This circuit replaced one stage of mechanical roughing-scavenging followed by two stages of cleaner flotation. General Column flotation continues to make inroads into applications traditionally dominated by mechanical flotation cells. For example, columns are becoming more visible as rougher flotation devices. At Royal Mountain King Mine in California, two 2.9-m-diam (9.5-ftdiam) columns are used for rougher flotation of carbon from a gold ore (Orlich et al., 1992). In addition, work performed at BRGM in France demonstrated the superiority of column flotation over mechanical flotation with respect to design of new plants (Morizot et al., 1991). The primary reasons for this acceptance of columns are a general improvement in design, scale-up and operation, as well as improvements in sparger design and performance. With these advances, the full benefits of column flotation can be realized. The benefits of properly designed, aerated and operated flotation columns include lower capital costs, reduced operating costs, fewer processing stages and improved metallurgical performance.

Jan 1, 1993

By D. Harris, M. Osterberg

This paper examines the economics of acquiring mineral exploration rights by royalty-rate bidding when the royalty basis does not provide for full cost recovery. Bidding takes place prior to exploration and the documentation of actual tonnage and grade. Consequently, it increases considerably the risk to exploration capital when the fraction of cost recovered is small and the product price exhibits large fluctuations. Price and grade risk are demonstrated on a 360-Mt (400-million-st) porphyry copper deposit by Monte Carlo simulation of discounted-cash-flow analysis. Copper price is modeled as a stochastic price process, and costs are based on US Bureau of Mines cost models. When both grade and price risk are considered, the probability for a negative NPV is 0.54, given a royalty rate of 5% applied to a basis that allows the recovery of costs up to 50% of product price. Investment risk could be considerably reduced by defining the royalty basis to allow greater cost recovery. Although such a basis would require society to share in the risk, society would benefit from greater resource development.

Jan 1, 2000

By Harold A. Taylor

The first use of graphite is lost in the mists of time. It was used by primitive man to make drawings on the walls of caves and by the Egyptians to decorate pottery. As early as 1400 AD graphite crucibles were being made in the Haffnerzell District of Bavaria. Through the Middle Ages graphite was confused with other minerals, especially galena and molybdenite. Two common names that are still being used for the mineral are plumbago, meaning lead-silver, and black lead. The latter name implied that graphite is either composed of lead or at least contains a large percentage of it. Gessner is credited with having recognized it as a separate mineral in 1565, but its composition was not determined until 1779, when Scheele demonstrated that graphite oxidized to carbon dioxide, thus proving its carbon constitution. In 1789, Werner named it graphite from the Greek word graphein, meaning to write. The United States has long relied on foreign countries for its graphite supplies. This reliance has been due more to the lack of suitable domestic graphites than to any particular preference for buying minerals overseas. Sri Lankan graphites were imported as early as 1820, and Madagascar graphites have been imported since the properties on that island were opened up about a hundred years later. Mexico has long supplied the United States with most of its requirements for amorphous graphite.

Jan 1, 1994

By Carlo Grandori

Early experiences The first double shield hard rock tunnel boring machine, manufactured in 1973, belonged to the generation of machines that were equipped with 12" dia. cutters. The experiences made with the 4.3 m diameter prototype ROBBINS mod 144-151 have been reported at the 1976 R.E.T.C. of Las Vegas (1): it might be worth recalling here that, with a specific cutter load not exceeding 10 to 12 metric ton and a 4.8 r.p.m. cutterhead speed, the average advance rate was of 350 meters per month of 21 working days with a peak production of 1,050 m of advance in 40 working days, in widely weathered and fractured granitic rocks of generally precarious stability, where a precast segmental lining was routinely installed as tunnel support. Over the 8.2 km of the Sila Tunnels, several badly crushed or sheared rock zones were bored through without major problems, even with water inflows of up to 30 1/sec. The same machine, with an improved design of the telescopic-and-floating shield area and equipped with flameproof drive motors, was taken to Colombia where, from September, 1979 to March, 1982 it drove 7.5 km of the Rio Negro-Chivor Tunnel in competent siliceous shales of up to 130 MPa at an average rate of 20 m/day.

Jan 1, 1987

By L. Tondo, W. Lim

The high pressure grinding rolls (HPGR) is a relatively new technology which offers the potential benefits in energy savings, circuit simplicity and improved product characteristics in minerals processing applications. Over 300 machines are now operating world-wide, but most of these are used for grinding cement clinker, and relatively few are used in conventional mineral processing. One of the rea- sons for its current limited use in the minerals processing industry is that design, scale-up and flowsheet assessment procedures are seen to be relatively immature and untested. This has reduced confidence in the potential application of the technology. To help rectify this situation an industry funded research project was undertaken, one of whose aims was to develop and prove a mathematical model of the HPGR and a scale-up procedure. Data were collected from tests using laboratory, pilot and in one case a full scale unit (2.2m diameter). A range of feed types were tested including quartz, limestone, kimberlite, bauxite, iron ore and gold ore. These data were then used to develop models of the size reduction performance, power draw, throughput and operating gap for a wide range of pressures, feed sizes, and roll speeds. This paper describes the models that have been initially developed and illustrates their accuracy using some of these data.

Jan 1, 1998

By K Martin, C. J. Nelsen, J. L. Schutz, S. R. Maynard

Investigations in the Ortiz Mountains have revealed the relationship of igneous activity and gold mineralization to the Tijeras-Canoncito Fault System (TCFS). The northeast-trending TCFS passes through the southeastern part of the Ortiz Mountains where its principal structure is the asymmetric Ortiz Graben. Several fault blocks, containing up to 305 m (1000 ft ) of Eocene Galisteo Formation, comprise the graben that has up to 1220 and 610 m (4000 and 2000 ft) of stratigraphic separation on its southeast and northwest sides, respectively. Intrusions in the Ortiz Mountains can be subdivided into two petrochemical types: an older calcalkaline suite and a younger alkaline suite. The calc-alkaline rocks are characterized by extensive sill, dike, and laccolithic bodies of latite-andesite intrusives and at least one younger (?) granodiorite stock at Candelaria Mountain. The alkaline rocks consist of a large nepheline-bearing augite-monzonite stock, a latite-porphyry hypabyssal plug, the Ortiz diatreme (vent breccia), and trachytic-latite dikes radial to the diatreme. K-Ar age determinations suggest the older suite to be 34 +/-2.2 million years while the younger alkaline rocks range from about 30 to 26 million years. Gold mineralization in the Ortiz Mountains occurs in five distinct environments: brecciapipes, skarns, veins, porphyry-like stockworks, and placers. Lode mineralization is associated with the alkaline suite of intrusive rocks postdating the Ortiz diatreme and predating most of the trachytic-latite radial dikes.

Jan 1, 1991

By D. A. Stanley

The Bureau of Mines has developed an equation which describes the dewatering of clay slurries with polyethylene oxide. This dewatering equation is An _ kC + b where n, k. and b are empirical constants and C is the concentration of polymer solution used for dewatering. The minimum amount of polymer required for dewatering. A is determined by titration of the clay slurry with a polymer solution. In this report, the dewatering equation is applied to data obtained for a polyacrylamide dewatering sequence. Fundamental similarities between the dewatering properties of clays and the viscosity of polymer solutions were observed. These similarities were explained by correlating an equation describing polymer configuration in solution with the dewatering equation. This correlation showed that amount of polymer required for dewatering and polymer solution viscosity are both consequences of the frictional interaction of entangled polymer coils.

Jan 1, 1989

By M. Canty

This paper presents results from pilot-scale and field testing of an innovative technology that uses sulfate-reducing bacteria (SRB) to treat and control acid mine drainage (AMD). Sulfate-reducing bacteria, a common group of anaerobic bacteria, produce hydrogen sulfide and bicarbonate when supplied with sources of carbon and sulfate. Hydrogen sulfide reacts with metal ions in AMD, precipitating them as metal sulfides. The bicarbonate produced serves to help neutralize the drainage. Pilot-scale metal-removal efficiencies reached 99% for zinc, 99% for aluminum, 96% for manganese, 98% for cadmium and 96% for copper. However, the iron and arsenic removals were not as effective as the aforementioned metals. This was largely attributed to high levels of iron and arsenic that contaminating the organic substrate. There was evidence that both adsorption and sulfate reduction were occurring within the reactors. The SRB field demonstration involved using the flooded subsurface mine workings of the Lilly/Orphan Boy Mine near Elliston, MT, as an "in situ biological reactor." In the mine, high removal efficiencies were observed for aluminum, cadmium, copper and zinc (70% to near 100%) during the four years of monitoring. However, for reasons similar to the pilot scale testing, low removal efficiencies were observed for arsenic and iron. Sulfate reduction was evident by measured decreases in sulfate and the detection of soluble sulfide within the mine water.

Jan 1, 2000