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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 K. Rajamani

A mathematical model based on the pertinent fluid dynamic equations to predict the performance of the hydro cyclone has been developed which will eventually replace the empirical model. Experimental measurements of fluid velocity profiles made in a 75 mm hydrocyclone by laser Doppler velocimetry (LDV) agree well their predictions by solving the Navier-Stokes equations numerically. Particle slip velocity and particle trajectory were computed which in turn, yields separation curve of the hydrocyclone.

Jan 1, 1988

By Charles Kimbell, L. Nahai, E. Shekarchi

INTRODUCTION AND SUMMARY World mineral trade during 1960 to 1984 has shown substantial changes both in value and tonnage. Although fuel commodities dominated total mineral trade during this period, this paper will focus attention primarily on nonfuel minerals. Brazil and Australia, modest producers of iron ore in 1960, have become dominant producers and exporters, together accounting for about half of major iron ore exports in 1984, far surpassing traditional export suppliers such as Sweden. Australia has also become the largest producer and trader of bauxite and alumina, and worldwide alumina trade has increased at the expense of bauxite trade. Similarly, shipments of ferroalloys have increased more than shipments of ores such as those of chromium and manganese. Canada, retaining its first rank in world export of zinc, has become also the leading source of potash and sulfur in world trade, and South Africa has been the dominant factor in chromite, manganese and their respective ferroalloys. Developing countries' share of world copper trade has increased, with Chile maintaining first rank, but developed industrialized countries have continued to dominate production and trade of lead and zinc. Phosphate, sulfur, and potash have been the principal crude nonmetallic minerals traded worldwide. Looking to the near future, dramatic increases in export of iron ore, phosphate, potash and sulfur are not envisaged. Bauxite exports will continue to decline relative to alumina but at a slower rate than in the recent past. Zinc concentrate will continue to be exported but lead will be traded more as metal than as concentrate. For iron and steel, there will be some production shift from traditional producers to certain developing countries and recently industrializing developing countries such as Brazil, India, the Republic of Korea, and Taiwan. In the following sections dealing with specific commodities, it should be understood that information is presented only on the major forms of each commodity that move in trade, and only for a selected group of countries for each commodity or major form of each commodity. Thus, totals shown or mentioned generally represent only the totals of figures presented here and do not include estimates for minor forms of material or for countries that are not listed. However, the data provided is regarded as sufficiently complete to reflect major patterns and trends, and exclusions are there- fore not seen as affecting conclusions that may be drawn from the material provided. FUEL AND NONFUEL TRADE Values of Fuel and Nonfuel Trade The value of world export trade in major mineral commodities (ores, concentrates and scrap, crude minerals, iron and steel, nonferrous metals, nonmetallic minerals and mineral fuels) in 1983, the latest year for which comprehensive data are available, was reported by the United Nations in May 1985 to have totaled over 514 billion current U.S. dollars (Table 1). This was 79% of the historic record high of nearly $649 billion ,current dollars set in 1980, but almost 18 times the current dollar value reported for 1960. [1/] The value of these 1983 exports in constant 1960 dollars was $164 billion (Table 2), only 66% of the record 1980 high of almost $250 billion, and only about 5.7 times the 1960 dollar level.

Jan 1, 1986

By Y. J. Wang

The ventilation network problem, having both fixed and nonfixed operating points as control devices, is examined in this paper. Emphasizing the concept of solving a system of n equations in n unknowns, this paper presents the generalized problem formulation, some conditions under which the problem does not have a unique solution, and a solution procedure based on the Newton (or Newton-Raphson) method. A numerical example is included.

Jan 1, 1989

By John T. Cantwell

INTRODUCTION The process engineer usually is responsible for the design operating philosophy and/or day-to-day operations of a process. Since instrumentation is an integral part of the operation, it is essential that engineers understand the general capabilities of the different types of control equipment available. Many "noncontrol" engineers have become involved with instrumentation for machinery monitoring and control as well as other plant applications. The advent of the microprocessor has led to significant changes in control, both in systems configurations and man-machine interfaces. Today's concept is called simply "distributed control." What is distributed control? Distributed control is exactly what the name implies; the control system is divided into several functional segments and spread out to cover a process. The systems are distributed for physical, functional, and risk reasons. Before delving further into the specifics of distributed control, let's look at the evolution of control systems to see how we got here. Instruments initially were located near measurement and control points in the field. Operators physically had to go to the instrument to change setpoints or take measurements. As processes became more complex, it became evident that a central control area was required. This allowed an operator to monitor and control many variables. The operator's effectiveness was increased dramatically, which resulted in greater efficiency, better quality control, and lower personnel requirements. At the same time, plants became much larger, control applications became more complex, energy became expensive, and the industry became more competitive. All of these factors placed pressure on process and production engineers to get the most for the money. The result was a continuing push to put more instrumentation into a central control room to maximize efficiency and productivity and minimize manpower. This chapter deals in some detail with devices for measuring physical and chemical properties of coal; devices for measuring the weight and weight-rate of flow of coal; devices for the monitoring and control of conveyor systems, solids inventory, fluid flow, liquid level, density, and specific gravity. These instruments have a multitude of uses throughout a coal preparation plant. The discussions cover advancements in "on-line analysis," nuclear control devices, and distributed control using microprocessors, mainframes, and soft-

Jan 1, 1991

By D. Butler

Lateral density changes in the subsurface cause a change in the vertical pull of gravity at the surface. By very accurate measurement of gravity and the practical application of common sense, a microgravity survey can sometimes detect natural or man-made voids, bedrock profiles, and geologic structures of engineering interest. This paper will give some practical guidelines for the application of microgravity surveying. Emphasis in many papers (Blizkovsky, 1979, Fajklewicz, 1983) has been on the anomaly size: herein emphasis will be placed on detectability and signal-to-noise ratios. First, some easy to use curves for anomaly valuation are adapted from Arzi (1974). Secondly, the predictable noise sources are discussed. Thirdly, representative models of abandoned underground workings are evaluated for microgravity surveying given the probable noise in the survey results.

Jan 1, 1988

By G. B. Michaels

Exploration programs for mineral resources often involve analysis of soils or stream sediments for the mineral being sought or its pathfinders. Because many metals are toxic to microorganisms, patterns of metal resistance in soil or aquatic populations may provide additional useful information at a reasonable coat. These patterns in some cases have been more effective than the soil geo-chemistry and may be easier to obtain. Elevated levels of resistance to silver and its path-finders have been demonstrated in stream populations from an area of known silver deposits, and resistance to gold pathfinders has been demonstrated for gold-bearing areas. Uranium has also been located by this method.

Jan 1, 1989

By S. P. Girrens

A coupled finite element geomechanical- hydrology code is currently under development for application to the problem of predicting groundwater disturbances associated with mine subsidence. The structural-fluid coupling is addressed by calculating the subsided mine geometry, with emphasis placed on determining the strata disturbance and locating damaged regions, for input into a hydrology code, which determines localized volume flow rates and aquifer fluctuations. Benefits from coupling will be best realized when field measurements, an additional aspect of the study concurrent with analytical investigations, indicating the relationship between increasing rock strain and increasing permeability are incorporated into hydraulic material descriptions. Hydrologic and struc- tural calculations are presented to demonstrate computational capabilities applicable to mine subsidence

Jan 1, 1982

By M. R. Rosen

CARBINDER Polymer 498 is a liquid organic taconite binder which significantly improves fired compression in both fluxed and acid pellets. It has been used commercially in both shaft and straight grate furnaces. This new binder produces an unusual wicking phenomenon during balling wherein the rate of movement of interstitial water is accelerated to the surface of the balls. The phenomenon is proposed to be responsible for the significant improvement seen in fired compression. This paper presents information as to the effect of CARBINDER Polymer 498 on green ball and fired pellet properties. It also describes the wicking phenomenon and discusses a reversal in the normal balling operation procedures required for successful agglomeration.

Jan 1, 1988

By K. O. Johnson

Contaminant transport of mine and mill tailings is controlled by the hydrologic flow regime and the geochemical mobility of the contaminants. Contaminant' mobility is primarily determined by chemical reactions occurring within an interface zone between the tailings and soil The large geochemical differences between tailings and groundwater create a disequilibrium in the groundwater with respect to the soils when seepage from tailings enters the groundwater. Precipitation and dissolution reactions involving the major chemistry occur to return the perturbed system to chemical equilibrium between groundwater and minerals. Retardation of trace elements depends upon the chemical character of the groundwater and the adsorption substrates. In the case of uranium mill tailings, the mobility of contaminants is controlled primarily by precipitation/dissolution reactions which neutralize the pH, modify the Eh (redox potential), and produce highly adsorptive substrate for retardation of trace elements.

Jan 1, 1988

By M. L. Clark

Advances in the recovery of gold from heap leaching are being made daily, but of all the systems vital to the maximum recovery of gold from a leach pile, none is more important than the methods used to construct the pile in preparation for the leaching operation. The technology described in this paper illustrates the latest systems developed to minimize compaction in the pile during its construction and reduce the cost of placement of ore on the pile. The Florida Canyon Mine of Pegasus is evaluated in detail to show reasons for its high degree of success to date.

Jan 1, 1988

By J. V. G. Middleton

The paper gives a comprehensive review of the design considerations which determined the choice of the milling plant, a description of the plant and comment on the operating experience to date. Operating experience will include inter alia a description of the mill liners installed with subsequent changes due to wear patterns, the mill inlet sealing arrangement, steel ball addition, mill outlet sump design, cyclone feed pump liner wear patterns and comment on the efficiency of the linear screens for wood chip and tramp removal. Finally a view on future trends in South African milling practice with respect to type and size of plant.

Jan 1, 1989

By E. Alan Haley

Accurate and economic control of line and grade on long tunnels, large structures, excavations and waterways, has been a problem to surveyors and engineers for decades. The conventional method of surveying, incorporating a level, transit, and a number of surveying technicians, has proven, in the past, to be a very expensive and time-consuming operation. Alignment with a laser has solved most of the problem. Figure 1. With the advent of the Perkin-Elmer Model 5620 Construction Laser, use of laser light is now both dependable and economically feasible for unlimited applications in modern construction and surveying. The laser projects a continuous, narrow red beam of brilliant light, providing a constant alignment reference, and will not interfere with operations.

Jan 1, 1968

By Robert B. Fulton, Gill Montgomery

Fluorspar is the commercial name for fluorite, a mineral that is calcium fluoride, CaF2. The name, derived from the Latin word fluere (to flow), refers to its low melting point and its early use in metallurgy as a flux. It is the principal industrial source of the element fluorine. Two other minerals, cryolite and fluorapatite, have significant fluorine content. Cryolite, sodium aluminum fluoride, Na3AlF,, is a rare mineral that has been found in commercial quantities only in Greenland. The natural material has been supplanted by synthetic cryolite for its principal industrial use in the manufacture of aluminum. Fluorapatite, Ca5F(PO3)2, is a source of phosphate for fertilizer manufacture, containing a small percentage of fluorine. Commercially mined deposits of apatite have varying amounts of fluorine, chlorine, hydroxyl, and carbonate. HISTORY Fluorspar was used by the early Greeks and Romans for ornamental purposes as vases, drinking cups, and table tops. Various peoples, including the Chinese and the American Indians, carved ornaments and figurines from large crystals. Its usefulness as a flux was known to Agricola in 16th century Europe. Fluorspar mining began in England about 1775 and at various places in the United States between 1820 and 1840. Production grew substantially following the development of basic open hearth steelmaking, wherein it is used as a flux. Use was stimulated by growth of the steel, aluminum, chemical, and ceramic industries, particularly during World Wars I and 11. Fluorocarbons entered the picture in 1931. The use of anhydrous hydrogen fluoride (HF) as a catalyst in the manufacture of alkylate for high octane fuel began in 1942. Differential flotation for separating fluorspar from galena, sphalerite, and common gangue minerals in the 1930s and the application of heavy media concentrating methods to the treatment of low grade ores in the 1940s were outstanding technological advances that facilitated increased production. Pelletizing and briquetting of flotation concentrates for use in steel furnaces and the development of flotation schemes for beneficiating ores containing abundant dolomite and barite have been major improvements in the industry. USES OF FLUORITE Fluorspar is used to make hydrogen fluoride (HF), also called hydrofluoric acid, an intermediate for fluorocarbons, aluminum fluoride, and synthetic cryolite. It is used as a flux in the steel and ceramic industries, in iron foundry and ferroalloy practice, and has many minor specialized uses. Hydrogen fluoride is produced by reacting acid grade (97% CaF,) fluorspar with sulfuric acid in a heated kiln or retort to produce HF gas and calcium sulfate. After purification by scrubbing, condensing, and distillation; the HF is marketed as anhydrous HF, a colorless fuming liquid, or it may be absorbed in water to form the aqueous acid, usually 70% HF. Synthetic cryolite, organic and inorganic fluoride chemicals, and elemental fluorine are made from hydrofluoric acid. The acid itself is important in catalysis in the manufacture of alkylate, an ingredient in high-octane fuel for aircraft and automobiles; in steel pickling, enamel stripping, and glass etching and polishing; and in various electroplating operations. The manufacture of one ton of virgin aluminum requires about 12 to 29 kg of fluorine content in synthetic cryolite and aluminum fluoride. This quantity, through improved technology and recovery practices, is being lowered significantly in countries with the most advanced technology (i.e., Australia and Sweden), while others (i.e., Surinam and South Africa), remain at the high end. Elemental fluorine is prepared from anhydrous hydrofluoric acid by electrolysis. Gaseous at room temperature and pressure, fluorine is compressed to a liquid for shipment in cylinders or in tank trucks. Elemental fluorine is used to make uranium hexafluoride, sulfur hexafluoride, and halogen fluorides. Gaseous uranium hexafluoride is used in separating U235 from U233 by the diffusion process. Sulfur hexafluoride is a stable high dielectric gas used in coaxial cables, transformers, and radar wave guides. Halogen fluorides have important applications, mostly as substitutes for elemental fluorine, which is more difficult to handle. Emulsified perfluorochemicals, organic compounds in which all hydrogen atoms have been replaced by fluorine, are undergoing investigation as promising blood substitutes. They transport oxygen and, in conjunction with a simulated blood serum, perform many functions of whole blood. With further development, these organic compounds may ultimately, in emergencies, be useful in saving lives of animals and humans during periods of acute shortages of natural blood. Inorganic fluorides are used as insecticides, preservatives, antiseptics, ceramic additives, and fluxes and in electroplating solutions, antioxidants, and many other products. Boron trifluoride is an important catalyst. Organic fluorides are volume leaders in the fluorine chemical industry. Fluorinated chlorocarbons and fluorocarbons are prepared by the interaction of anhydrous HF with chloroform, perchlorethylene and carbon tetrachloride, and are characterized by low toxicity and notable chemical stability. They perform outstandingly as refrigerants, aerosol propellants, solvents, and cleaning agents and as intermediates for polymers such as fluorocarbon resins and elastomers. Fluorocarbon resins are inert compounds that have unusually low coefficients of friction and have found a number of applications as lubricants for parts that cannot be oiled, e.g., bearings for window raising equipment located inside of automobile doors, in small electronic equipment, for the manufacture of chem-

Jan 1, 1994

By David D. Eyer

Since the decade of the 1990s is nearly upon us, I have focused on what I see are the likely trends featured in new large underground coal mines 10 years from now. I do this from the vantage point of having been involved in the installation of large mines for more than twenty years. Little of the equipment resources we have available today was unknown when I entered the coal business in 1960. There were continuous miners, longwalls and diesel-powered equipment in Europe, monitoring systems, computers, heavy media separation systems, froth flotation and conveyors then as there are now. A substantial evolutionary process has occurred with these and other mining machines and processes. Some evolved only to die out, such as boring-type continuous miners; others, such as longwall systems, flourished. My intuition tells me that since there have been largely evolutionary rather than revolutionary developments in the near past, the same is true of the future, at least for the next 10 years. In other words, the elements of what are in the future are with US now. Some, such as computer-based applications, may evolve beyond our wildest dreams -but I doubt it.

Jan 1, 1988

By C. I. Basilio

The adsorption of O-isopropyl-N-ethylthionocarbamate (IPETC) and O-isobutyl-N-ethoxycarbonylthionocarbamate (IBECTC) on chalcocite, chalcopyrite and pyrite has been studied using UV and in-situ FTIR~ATR spectroscopy. Thionocarbamates were found -to adsorb strongly on chalcocite at pH 4-10, but consider-ably less on chalcopyrite and pyrite. The FTIR spectra show that the surface species of thiono-carbamates are bonded to metal atoms on the mineral surfaces. However, at high concentrations, IBECTC also forms physically-adsorbed species. Adsorption of these thionocarbamates cannot remove or prevent the formation of sulfoxy oxidation products on pyrite, unlike the case with the xanthate-pyrite system. This finding may account for the observed flotation selectivity of these reagents against pyrite. The spectroscopic information is compared with flotation test results.

Jan 1, 1988

By B. C. Williams

The Bureau of Mines monitored the water quality in and near a copper/gold tailings impoundment. Samples were taken from the unsaturated %one. and dissolved concentrations of over ZO constituents were measured with respect to depth and moisture content, factors which influence oxygen content and sulfide oxidation. Samples from the unsaturated %one were drawn through a hypodermic needle sampler into individually evacuated vials fitted with septa, thus preventing oxygen contamination. Water quality was also monitored in the saturated tailings, underlying colluvial aquifer, and weathered andesite bedrock.

Jan 1, 1989

By H. Yoon

Several processes involving injection of sorbent and humidification water downstream of the air preheater in a coal-fired boiler unit, are being developed as low capital cost retrofit S02 control options. Extensive laboratory work, pilot plant programs and larger scale programs have developed performance data and design information. Many of these programs were supported by the U. S. Department of Energy (DOE) as "proofs-of-concept" of three different processes proposed by Dravo, Bechtel and General Electric. Based on these project results, DOE formulated a comprehensive in-duct sorbent injection development program to fully commercialize the technology by 1992. Also, EPRI will conduct a 4 MWe pilot program to develop its HYPAS process. The Consol Coolside process is scheduled for utility demonstration in 1989 on a 104 MWe unit at the Ohio Edison Edgewater Station under partial sponsorship of the DOE Clean Coal Technology Program.

Jan 1, 1989

Effective ground control in the gate entries, particularly in the tailgate travelways, is essential for safe longwall mining. Longwall pillars maintain gate entry stability and carry abutment loads. To answer the need for effective longwall pillar design, an empirical method called Analysis of Longwall Pillar Stability (ALPS) was proposed several years ago. Some recent research at the Bureau of Mines has focused on the refinement and verification of the ALPS method. ALPS was originally developed from field studies in which multiple stressmeters were installed in longwall pillars and monitored during mining. Several new field studies have now been incorporated into the ALPS data base. The field measurements have' been used to verify formulas for predicting abutment strength and pillar loads, and to develop an expression for the distribution of the abutment load.

Jan 1, 1989

By Clayton J. Parr, Northcutt Ely

Mining law is essentially a branch of the law of real property. It concerns acquisition of property for extracting contained minerals, and the rights, privileges and duties that fall upon the holder thereof once the rights are acquired Accordingly, this section focuses on the procedures to be followed in acquiring state. federal and private lands, and defines briefly the nature of the rights obtained. The mining laws of Canada and Mexico are summarized, and the related subjects of minerals taxation and governmental regulation are discussed briefly. This section is not intended to be the basis for legal decisions. Rather, its purpose is to provide the engineer with an understanding of basic principles and procedures. For a detailed treatise of mining law, reference can be made to The American Law o] Mining, a five-volume set edited by the Rocky Mountain Mineral Law Foundation. The law changes constantly, especially that based on federal and state statutes, and the reader is cautioned to be alert for subsequent modifications of statutes, regulations and case law. 2.1-PRELIMINARY LAND-STATUS CHECK Often, after completion of area reconnaissance, or perhaps after receipt of a submittal, a specific more localized target area will become of interest. Usually, an intensive exploration program comprising detailed surface mapping, sampling, geophysical prospecting and drilling will be required before the mineral potential of the ground can be properly evaluated. Before an investment of this magnitude is made, however, it is advisable to obtain rights to mine ore from the property. Otherwise, knowledge of the exploration activity might greatly inflate land values, or speculators or competing mining concerns might step in. Hence, as a general rule, a land-acquisition program should be undertaken before an intensive exploration project is begun. The first step in such a program is to make a land-status check to determine whether the subject lands are available and, if so, from whom they can be obtained and by what means. 2.1.1-BUREAU OF LAND MANAGEMENT RECORDS In those states which contain large areas of federal land, basically (he western states, the primary informational source is the records of the Bureau of Land Management. These may t)e examined at the land office having jurisdiction over federal lands in the area of interest. The records for Montana and North and South Dakota are kept at the Billings (Mont ) land office; Wyoming, Nebraska and Kansas, Cliejenne, Wyo.; New Mexico, Oklahoma and Texas, Santa Fe, N M ; northern Alaska, Fairbanks, and southern, Anchorage; Utah, Salt Lake City; Nevada, Reno; Arizona, Phoenix; Colorado, Denver. There are two land offices in California, at Sacramento and Los Angeles Records for other states are kept in Washington, D C. at the office of the Director, Bureau of Land Management.

Jan 1, 1973