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By Daniel C. McLean

Chemistry plays a more important role in milling operations than is generally recognized, particularly in fluid- solid separation processes. Chemical aspects are also very important insofar as plant water quality is concerned, and in the manner in which this water quality effects plant design and operation. Aside from the inherent chemical characteristics of plant water, the mineral preparation industry is becoming increasingly more dependent on the use of mining chemical reagents--relatively new to the coal industry, but items of I standard usage in complex metal recovery plants. These chemicals have many useful properties and can produce significant improvements in operations and metallurgical efficiencies when used properly and intelligently. They can produce poor results and sometimes severe losses when used improperly. Most reagents are relatively expensive on a per pound basis, hence costs can be excessive if they are used wastefully or inefficiently.

Jan 1, 1968

By Francis S. Kendorski

INTRODUCTION Caving offers the lowest cost per ton of any large-scale mining method, but its successful application demands an ore body that conforms to several rigid requirements. The deposit must be of wide areal extent, massive and not spotty in ore values, and insensitive to ore dilution. It must also be a rock mass that breaks up readily. There are only three active caving operations in the US-Climax, Henderson, and San Manuel-but caving methods have recently taken on new importance as deeper lower grade mineral occurrences and ore bodies are found. These deposits are too deep for surface min¬ing methods, and too low grade to support any type of underground mining except a bulk method such as caving. Announced discoveries or indications that may be amenable to caving include: Climax's Mt. Emmons molybdenum discovery in Colorado; Molycorp's Goat Hill molybdenum prospect in New Mexico; the Phelps Dodge molybdenum deposit in Beaver County, UT; Arizona copper occurrences such as Asarco's Sacaton, Hanna's Casa Grande, Noranda's Lakeshore, and Ken¬necott's Safford; Anaconda's suspected deep copper de¬posit in Butte, MT; Anaconda's Carr Fork, UT, deposit; and perhaps others. CAVABILITY'S ROLE IN FEASIBILITY STUDIES Caving is a system of underground mining which removes support from underneath an ore body. As a result, the rock mass fractures, fails, and flows vertically downward by gravity to be collected in previously ex¬cavated funnels. Types of ore that have been mined by caving include molybdenum, copper, iron, nickel, as¬bestos, and diamonds (Julin and Tobie, 1973). It is primarily a large-scale method, with production rates of more than 45 300 t/d (50,000 stpd) having been achieved. However, the initial capital investment before return is very high, often in the hundreds of millions of dollars. The cavability of an ore body or mineral occurrence is a critical item in the feasibility study of a proposed mine, not only from the point of overall minability, but from the point of impact on other costs such as blasting, loading, hauling, crushing, and grade recovered. Aside from the often-asked question of, "Will it or will it not cave?" the real questions are, "Can we afford to make it cave, carry the rock away, and extract the mineral?" The last is not a topic of this chapter, but the first two are. The cavability of an ore deposit or mineral occur¬rence is based on many things, but clearly, if a large enough area is undermined, any rock mass will cave. The result could be a violent collapse as occurred at Urad, CO (Kendrick, 1970), or perhaps the rock mass will cave beyond the ore boundary. Another unfavor¬able result could be ore blocks that are too large for the equipment and orepasses to handle without considerable secondary blasting. Weak rock with numerous fractures may produce a very fine ore when it caves, resulting in dilution and ground control problems. DETERMINING STRUCTURAL DOMAINS It has long been recognized that the geologic nature of an ore body is important to cavability (King, 1946). Such items as weak rock material, intensity of fractur¬ing, and severity of faulting all contribute to the success of a caving operation, and information regarding these is required as a minimum for the cavability determination. In practice, the rock mass-defined as the blocks of intact rock together with the intervening fractures, joints, faults, bedding planes, and other discontinuities-that contains the ore body, as well as the surrounding and overlying rock, must be examined in a systematic and detailed fashion. Surficial geology maps must be pre¬pared, exploration holes drilled, and core logged for en¬gineering information. The fracturing of the rock mass must be studied to ascertain the three-dimensional dis¬tribution of fractures and their characteristics, and faults must be located and described. The strength and other mechanical properties of the rock material, the fracture surfaces, and the fault filling materials must be tested and reported for later use by designers and planners. With this basic information and an understanding of the geologic setting, the rock mass can be divided into one or more structural domains which tend to behave similarly in response to engineering activities (Robertson and Piteau, 1970). One must keep in mind that the determination of the structural domains goes beyond the geologic units present. Several lithologic units may be lumped together, while a single lithologic unit can be divided into multiple domains. Major faults often form their own domain, and the direction of engineering ac¬tivity-for example, cave advance to the north rather than the south-may alter rock mass behavior, resulting in different domains. As an example of the detailed rock fracture map¬ping required for such studies, the structural domain determinations at the Climax mine (Kendorski, 1973) are shown in Fig. 1. The circles are Schmidt equal area projections of the three-dimensional attitudes of frac¬tures (Ramsay, 1967) mapped in detail at various rock exposures. The attitude of fractures is important to the cavability determination since it dictates the directional behavior of the rock mass as it fails, and determines the effectiveness of arching, keying, and rock block inter¬locking. Low-angle fractures must be present to allow movement of the rock in the vertical direction during undermining (Mahtab and Dixon, 1976); if low-angle planes of weakness are absent, the rock mass may arch with a keystone effect, rather than moving vertically downward.

Jan 1, 1982

By M. D. Baker

Coal-water slurry preparation requires fine grinding and cleaning of coal by flotation. Finer grinding leads to increased ball wear and its effect on the surface properties of coal becomes of concern. Marked ball wear tests were performed to study the effects of oxygen, pH, the soluble species of coal and the addition of pyrrhotite on ball wear. The synergistic action of coal and oxygen greatly enhanced the corrosion of mild steel balls during grinding. Electrochemical measurements on a mild steel electrode in coal slurries and SEM observations of grinding ball surfaces were carried out to explore the corrosive wear mechanism.

Jan 1, 1989

By Kadri Dagdelen

The classification of selective mining units (SMU) and the assignment of grades to those classified SMU are very important in open pit mining, especially for precious metal mining. When the classification is done, the true values of the SMU grades are unknown. These unknown SMU grades are mostly estimated analyzing the geologic data and blast hole assays. To classify the SMU's based on the estimate of SMU grade, without considering uncertainty associated with unknown SMU grade, yields incorrect decision in sending material to appropriate destination. In this paper, a method is developed to classify SMU's considering the uncertainty associated with unknown SMU grades. By using this method, traditional estimate of SMU grade is replaced with conditional probability distribution of SMU grade. The decisions about the destination of a given SMU are performed by minimizing the loss due to misclassification. Also, the asymmetric loss function by penalizing the overestimation and the underestimation unequally is used in assigning grades to classified SMU's. A case study is carried out to apply the traditional ore control techniques and proposed method in classification of SMU's and the assignment of the grades in a hypothetical gold mine.

Jan 1, 1999

By Marini David, Pigorini Andrea, Fuoco Stefano, Zurlo Raffaele

"The excavation of a tunnel in highly weathered and strongly fractured rock masses due to tectonic actions is still a challenge. In order to maintain reasonable productivity, excavation through a wide zone of highly tectonized rock mass requires a detailed, integrated study of the construction solutions and a monitoring system to minimize the process time and to optimize the adopted consolidation measures in accordance with a predefined matrix of possible support systems. This paper summarizes some interesting data acquired during the excavation of the Brenner Railway Base Tunnel system between Italy and Austria. The Brenner Base Tunnel (BBT) runs through the fault line between the European and the African tectonic plate. This big fault zone is called “Periadriatic Line.” In particular, data acquired in the exploratory-service tunnel have been analyzed. Furthermore, the base concepts for defining the consolidation and support solutions adopted for the excavation of the exploratory tunnel are described. INTRODUCTION The Brenner Railway Base Tunnel (BBT) is a system of underground structures and tunnels that is designed to connect Italy and Austria using new railway standards. It is based on high speed (HS) concepts and applies the European Standards for Interoperability (TSI). The railway includes twin tunnels for a total length of about 55.0 Km without considering the connection tunnels to the existing underground railway in Innsbruck. Including the latter, the total length of the tunnel system reaches 64 Km, and is among the longest tunnels in the world. The Italian section passes through the so-called ""Periadriatic Line,"" which is an important tectonic structure generated by the collision between the European and the African tectonic plates. Despite the extensive investigations carried out (boreholes down to 700 meter depth), significant geological and mechanical uncertainties inside the Periadriatic formations remained unsolved. In order to elevate the level of confidence and observe the behavior of the rock mass at a representative scale, the BBT Authority decided to excavate in advance the service tunnel, which has taken the function of an exploratory tunnel. The data and observations collected during its excavation would provide important insights for the design of the main tunnels."

Jan 1, 2016

By Michael C. Newbury

For thousands of years gold has been not only a commodity, valued for its comparative scarceness, immutability and homogeneity but also a medium of exchange which has no nationality. Approximately 90% of the gold produced is still accessible in the world, although some of it in museums, galleries, jewellery and dental work is not immediately available for circulation. The majority is held as bars by central banks for their reserves; the balance circulates as coinage or bullion held for investment. The value is further enhanced by the political aspect that gold cannot be debased as paper currency can and, therefore, it always becomes an investment refuge. It has always been possible to buy and sell gold at a price which is readily established by reference to bullion's weight and purity; and it is this fact which makes a loan denominated in gold, rather than one in currency, a viable alternative means of finance. The purpose of this paper is to discuss some general aspects of what is considered to be one of the more effective and presently popular methods of financing the development of a gold mine - the gold loan. This is not intended to discuss all the minute details which must be uniquely designed to fit each individual situation, but rather to provide general guidelines. You will all be aware of the traditional sequence whereby companies primarily finance exploration work by the raising of equity through the sale of shares to the public or by that unique Canadian form.

Jan 1, 1987

By R. O. Burt

Gravity concentration - the separation of minerals according to their relative density - is one of the oldest forms of mineral processing. Even though modern technology has developed a range of other processes, gravity concentration remains as one of the most important methods employed for mineral separation. The range of minerals recovered covers a wide spectrum, from andelusite to zircon, from coal to diamond, from gold to industrial mineral. The long history of gravity concen¬tration, along with a still imperfect understanding of the various mechanisms involved has resulted in a series of ingenious engineers developing, some¬times perfecting and sometimes rejecting, a wide range of equipment, suited for a variety of different duties. 'Selection' in the context of gravity separation, is primarily the choice of the right type of equipment for the separation in hand; 'sizing' of the correctly chosen unit is, more often than not, determining the appropriate number of units required to suit the throughput. The accent of this chapter will, therefore be 'selection'. A brief description of the major types of gravity concentration equipment will follow a discussion of the factors which determine the selection of the correct unit. CLASSIFICATION OF GRAVITY CONCENTRATION EQUIPMENT All concentration equipment has a primary function and a secondary function. The primary function is the efficient separation of the constituent minerals into two or more discrete phases; the secondary function is to effectively cause the discharge of these discrete phases into separate compartments (Aplan 1975). For maximum efficiency of operation, the forces which effect the primary function should not also result in the secondary function occurring; in such cases optimum operating conditions required for the primary function, separation, may have to be compromised to ensure reasonably efficient operation of the secondary function, product discharge. With gravity concentration, the primary function is effected by the relative movement of minerals of different density in response to gravity and one or more other forces, the latter often including the

Jan 1, 1986

By Jeffery L. Kohler

The research and development of a pattern recognition system which can predict incipient failures and safety hazards in the mine power network is described. An examination of mine electrical safety hazards revealed they are often related to the electrical equipment down-time experienced on mine sections. Based on this, a method is proposed that can improve both production and safety, without compromising either. Equipment failure modes are examined to illustrate how the ultimate failure can be predicted for enough in advance to allow a convenient and safe repair, followed by a discussion of actual monitoring system performance. Finally, the paper is concluded by projections of the system's utility to industry.

Jan 1, 1977

By T. Reed Scollon

Before we can attempt to answer the question of what can be expected from coal research, let us examine why research is done in other fields and what others expect for the money they spend on research and development. Up to 1900 almost all organized research was carried out at universities. Most of the support came from the university, and by present standards the amount of research was extremely small. The motivation for university research was basically discovery of new phenomena, with the objective of advancing knowledge. Side by, side with this organized effort was that of individual inventors who were primarily responsible for applying this new-found knowledge to useful purposes. During this period inventors were rarely supported by anyone, and experimentation was carried out either in their spare time or at the expense of earning a living. Men like Edison, I believe, were the first to demonstrate on a large scale that one could systematically apply newly discovered scientific principles to inventions that would serve useful purposes and would return a profit to those engaged in the effort. The tremendous expansion in research therefore began with the realization and demonstration that the scientific discovered could be applied in such a way as to return a' handsome profit to those who invested in it. The motivation of many of the research personnel however, remained the satisfaction associated with new discoveries, The money to support their efforts came from those interested in a return on their investments. Since the First World War and a rapidly accelerating rate since the Second World War another important motive for supporting research has appeared--the needs associated with national defense; this type of research has been supported almost exclusively by the Government.

Jan 1, 1959

By Lawrence A. Roe

This paper describes research and development efforts leading to a wet process for the beneficiation of Western talc ores in which the values are primarily present as soft, platy talc mineral. The mineralogy of the ore, as it relates to the logic of utilizing an uncomplicated, attrition-scrubbing sedimentation process is described. Bench-scale laboratory testwork and a pilot-plant test program are described. The pilot-plant program included production of several tons of products. The thickened talc slurries were very difficult to dewater prior to the drying step. Dewatering difficulties were overcome by use of a high-speed centrifuge. The centrifuge cake was dried either by tray, flash or spray drying. The successful use of one high-grade talc product as titanium dioxide extender in paper is discussed. The talc product has extremely low abrasion values, an important characteristic for minerals used in paper manufacture. It is concluded that this wet process for soft talc ores is capable of producing high-purity talc products for paint, paper, cosmetics and other industrial uses re-quiring very pure soft talc.

Jan 1, 1972

By J. Herbst, I. Heber-Panu, Dan G. Cojocariu, E. Ene-Danalache, G. Poling

A general model which represents not only batch but also continuous flotation in multi-cell machines is presented. This model considers both the size distribution and the distribution of flotabilities in a size class for valuable mineral particles in the pulp. The general expression is shown to reduce to several previously reported models. In addition, a number of new models are found to arise for different specific assumptions concerning the flotability distribution and/or the size distribution of the particles undergoing flotation. Several of these new models are tested experimentally using laboratory-scale batch and pilot-scale continuous data. Model parameters are estimated from this data and a comparison of calculated recoveries and those experimentally determined are presented. Finally, the influence of the feed rate, aeration rate and valuable mineral content of the feed on the recovery is examined.

Jan 1, 1976

By Mark D. Cocker

Georgia?s Coastal Plain contains important sediment-hosted deposits of kaolin, bauxite, heavy minerals, sand and gravel, silica sand, carbonate rocks, and fuller's earth. Genesis, location, size, and quality of these deposits are related to terrestrial, marginal-marine, and shallow-marine depositional environments that evolved during development of the southeastern North American continental margin. From the Cretaceous to Eocene, kaolin and aluminous sediments, which contained mica and feldspar, were deposited in marshes, ponds, and bays located in deltas or behind barrier islands or spits. In the Cretaceous sediments, subsequent, intensive, in situ chemical weathering converted mica and feldspar to kaolin. Kaolin eroded from deeply weathered granitic rocks in the Georgia Piedmont was deposited in Paleocene to Eocene sediments. Subaerial exposure during the Paleocene and Eocene desilicated kaolin sediments to form bauxite. Sand and gravel, silica sand, and heavy-mineral deposits are found in Cretaceous to Eocene fluvial and shoreline sediments, some of which are associated with the kaolin and bauxite deposits. Source areas, intensive chemical weathering in the source areas, transportation by the major river systems, and deposition of these clastic sediments in similar or nearby depositional environments are common elements in the genesis of these resources. Eocene fuller's-earth deposits are opaline claystones in near-shore to shelf-marine sediments, which overlie the kaolin-bearing strata. These claystones consist of montmorillonite and opal/ cristobalite derived from alteration of diatom frustules. Favorable ocean currents provided nutrients for extensive planktonic growth. Oligocene and Miocene carbonate rocks were deposited principally in shallow-marine embayments. Miocene fuller's- earth deposits in south-central Georgia and adjacent parts of Florida contain palygorskite that formed through alteration of montmorillonite/bentonite clays. Deposition and subsequent alteration occurred in shallow, brackish-water lagoons under relatively high temperature and subtropical conditions. Middle and late Miocene phosphorites were deposited on a shallow carbonate-shelf platform and were concentrated proximal to anticlinal highs. Numerous marine transgressions and regressions since the beginning of the Pleistocene resulted in shoreline detrital deposits containing aggregate sand, silica sand, and heavy minerals on the Coastal Plain and on the Continental Shelf. Major river systems transported sand and heavy minerals from source areas in the Piedmont and Upper Coastal Plain. Deltaic deposits of heavy minerals were redistributed and concentrated by longshore currents, shoreline processes, and aeolian processes. River-terrace sediments, correlative with the Pleistocene shoreline deposits, contain sand-and-gravel and silica-sand deposits. Aeolian dune sands are associated with both Pleistocene fluvial and shoreline detrital deposits.

Jan 1, 1999

By J. A. Folinsbee

Placer Dome Canada owns and operates the Campbell Mine at Balmertown, in the Northwestern corner of the Province of Ontario, Canada. The mine operates at 1500 stpd and produces in excess of 300,000 oz of gold annually. Recent changes to the gravity concentration circuit have resulted in a 10-15 % increase in gravity recovery. The circuit changes responsible for these improvements will be the focus of this paper.

Jan 1, 1997

By Harry M. Conger

Kaiser Steel Corporation's Eagle Mountain Mine is located in the Colorado Desert, 60 miles east of Indio, California. Concentrates from the mine are shipped by rail 164 miles to the company's steel mill at Fontana, and also to Longbeach, California for export. Temperatures are typical of the lower desert ranging from a high of 120 degrees in the summer to a low of 25 degrees in the winter. The average annual rainfall of about two inches comes mainly as cloud bursts during the summer months. From its inception, the Eagle Mountain Mine has had the problem of breaking its mine rock. Practices followed from 1949 until 1962 were very costly, did not produce uniformly good fragmentation, and were incapable of sustaining high production. During this period, every conventional type of explosive then in use was tried and found to be unsatisfactory for one reason or another. The first slurry test work at Eagle Mountain was started in 195E and finally by 1962, after having tried all the slurry mixtures then available including some "home made" formulas, a metallized slurry was perfected at the mine which overcame all of the disadvantages of former blasting methods.

Jan 1, 1965

By Ernest L. Bradley

A positive pressure ventilation system, augmented by a dewatering well curtain and underground longhole drilling, provides effective ventilation and radon control at EXXON Minerals Company's Highland Underground Mine in the Southern Powder River Basin of Wyoming. Testing different types of bulkheads, sealants, and bleeder systems has led to improvements in the basic ventilation system. Continued testing of new or different materials and equipment is expected to lead to further improvement in the ventilation program. Effective training of both miners and supervisors is essential to maintaining and improving ventilation techniques. This paper addresses the ongoing ventilation program and experience to date at the Highland Uranium Mine.

Jan 1, 1979

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 Gealy W. Wallwork

The administrative processes of coal mines are becoming increasingly complex. As society evolves into a more complicated structure with greater emphasis on individuality, government regulations reach deeply into every activity in an effort to force individuals into a standardized mold. These contradictory pressures add an extra burden to the administration of a mining operation. Recent years have brought a substantial change in the skills needed by mine supervisors and managers. As a result, a better understanding of the administrative functions is necessary. The mine superintendent has the overall responsibility for the mine; for effective operation he must be sufficiently knowledgeable to oversee all the complex functions that make up the mine. This chapter does not cover all the administrative requirements because of the variation in mine operation and in company policies and organizational structure. It does attempt to identify the administrative functions that would be required at a large mine with a preparation plant. It is assumed that the mine operation is decentralized with very little duplication of functions at the organizational levels above the mine. Thus each function is assumed to be relatively complete at the mine and under the general supervision of the mine superintendent.

Jan 1, 1981

By M. L. Maniocha

Most magnesia, MgO, whether of natural or synthetic origin, is utilized in its dead burned or periclase form as refractory linings for the production of steel. Continued research in refractory science combined with good refractory maintenance and improvements in steel making practice have resulted in decreased use of magnesia. To make up for this loss of business producers of synthetic magnesia have started to manufacture a variety of magnesium based chemicals that are utilized in many diverse industries and applications.

Jan 1, 1997

By R. L. Pozzo

The electrochemical nature of mineral-grinding media interaction in the wet grinding of one and two sulfide mineral ores was investigated with regard to the flotation behaviors of the minerals. Two iron sulfides (pyrite and pyrrhotite) and mild steel were used to represent the sulfide minerals and the grinding media, respectively. Galvanic currents in two-and three-electrode combinations under abrasive and non-abrasive conditions were correlated with the floatabilities of these minerals under corresponding conditions.

Jan 1, 1988

By Kenneth A. Grace

Each and every mining operation from a simple sand-and-gravel pit to the largest integrated mine-mill-concentrator-smelter-refining complex has, as its foundation, a quantity of extractable natural resource the reserves. Without reserves, there is no mine, and any concentrating or extracting plant, no matter how sophisticated, is simply so much scrap metal. And, of course, without resources there are no reserves. It is remarkable, therefore, especially in this age of careful planning, high quality engineering, and state-of-the-art financial analysis, that such a fundamental and vital item is so little understood and the subject- of so much confusion. Time and time again it has been the experience of the author, when called in to a mining operation that has run into trouble in reaching projected production targets, to find that the designed-for tons were not reaching the concentrator/extraction plant, and/or the grade of such tonnage was substantially below the forecast and design grade of the plant. The mill blames the mine for delivering below standard tons and/or grade and the mining engineer blames the geologist for overly-optimistic assessment or incorrect interpretation of the deposit. The geologist blames the mining and metallurgy division for wrongly interpreting his data and conclusions, or simply fouling-up a fine orebody.

Jan 1, 1983