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By Robert Mermelstein, Robert W. Kilpper

In a long term toxicology study SPF, F-344 rats were exposed 6 hours/day, 5 days/week for up to 24-months to a special test toner at 0, 1 (low), 4 (medium), and 16 (high) mg/m3, or Ti02 at 5 mg/m3, or Si02 at 1 mg/m3 by the inhalation route. The test toner was composed of about 90% random, high molecular weight acrylic copolymer and 10% high purity, medium color, furnace type, carbon black. It was enriched in fine particles such that the respirable aerosol concentrations (ACGIH) were to 0, 0.35, 1.4 and 5.6 mg/m3. There were no effects of exposure on survival, causes of death, body weight, food consumption or clinical chemistry and hematology parameters. There was no evidence for systemic or upper respiratory system toxicity as all of the changes were restricted to the lungs and associated lymph nodes. The lung tumor frequencies in the control (air and Ti02) and toner exposed groups were comparable. There were no changes at the low exposure level, which is the most relevant in regard to potential human exposures. The lung changes at the high exposure level consisted of decreased alveolar clearance, increased toner retention, increased lung weight, chronic inflammation, decreased pulmonary function and a moderate degree of focal fibrosis in all animals. The changes in the middle exposure level were smaller in magnitude than at the high level, and a very slight degree of fibrosis was found in 20% of the animals. In a follow-up investigation, female F-344 rats were exposed to one of three toner concentrations; control, low (10 mg/m3) or high (40 mg/m3) for 13 weeks followed by five, 13 week observation intervals. At the low exposure level, slight clearance retardation and modest inflammatory changes were observed at the end of exposure. They returned to normal values within six months post-exposure. In contrast, at the high exposure level, increased lung weight, decreased alveolar clearance and a disproportionate increase in toner retention, as well as an inflammatory response, were noted, which persisted throughout the post-exposure interval. While no significant histopathological changes were noted at the end of exposure, a very slight degree of fibrosis was observed in all of the animals in the high exposure group, after 65 weeks of observation. All of the above alterations are ascribable to "lung overloading", a generic response to excessive amounts of any dust retained in the lungs for a prolonged time interval. Published accounts in the toxicology literature document that long-term inhalation of large quantities of even innocuous particles such as Ti02, carbon black, petroleum coke, toner, and other polymeric and insoluble materials has resulted in a spectrum of generically similar pulmonary changes. Scaling of the rat-data, using 1 mg dust/g of lung as a threshold for "lung overloading", normal ventilatory parameters and 300-500 day human retention halftimes project "lung overloading" upon long-term exposure to insoluble respirable dust above 0.2-0.33 mg/m3. Other types of information are consistent with an exposure limit in the range of 0.4-1.0 mg/m3 for respirable dust. The absence of definitive toxicology data in support of the current OSHA respirable nuisance dust limit, coupled with the lack of sound epidemiology data, indicate the need to reexamine the validity of the current nuisance dust health standard.

Jan 1, 1991

By Spencer R. Titley

The subject of this lecture, a late century perspective on porphyry copper geology, is one of current interest and importance as the search for these ores remains intense. It is presented in the belief that an appreciation of our present understanding of the subject requires it to be viewed historically, thus providing a basis for evaluating appropriate directions for con¬tinued study. At the outset, it is important to note that the technology of mining and extractive metallurgy has developed ore from these low grade orebodies, starting with D. C. Jackling, and has continued to create them as copper grade and price have diminished. But the continued search for them is a geological problem that responds to growing expectations of people and societies; exploration based upon ever increasing knowledge of the habits of the ores has been very successful. This is the story of evolution of geological thought and practice in porphyry ore search across an interval of time beginning with the bulk mining of "low grade copper ores at Bingham and ending with late Century concepts. "How did we get here?" The lecture concerns the ideas of many different people. The ideas and events discussed reflect a bias on North American thought, where the great low grade orebodies were first recognized as such and where many of the basic geological ideas were developed. A very great number of geologists have contributed to this understanding. In no sense is it meant to minimize the contributions to the story that have evolved in the study and mining of ores of the Andes, whose development and expansion has been nearly synchronous with that in North America - nor to minimized comparable contributions made in the late century from studies of the newer discoveries of deposits in other regions, especially the southwestern Pacific regions. In expansion of this topic, I have found that many important concepts are marked by appropriate publication but some are not, or I have not been able to discover documentation. Many notions appear to have become conventional knowledge without publication, mostly being geological viewpoints developed synchronously from similar observation. Thus, apologies are extended in advance to those whose work I have might have missed and to those unknown to me whose unpublished ideas may have seeped into the pool of common knowledge without appropriate recognition. . The analysis here addresses events of two time segments, an older one extending from the developments at Bingham in the early 1900s through the Second World War, ending about 1950; the second period extends from that time to the present. This separation is seen in Figure 1, which traces numbers of publications through the period as extracted from some 700 publications, again with a North American bias, from an annotated bibliography of porphyry copper geology in preparation. During the early period, exploration was "immature" in North America, that is, geologists looked for new districts and sites of the deposits. Outcrops were sought that carried the signatures of former mineralization and regional controls related to structural geology were closely studied. In the later period, North American exploration had "matured" into a study of districts, rather than a search for them. As the studies of these ores intensified during the younger period concommitant with increasing demands for the metal, they did so with a broadened understanding of some habits of occurrence, of hydrothermal alteration, mineral zoning, petrology, and geochemical and geophysical signatures. Outside of North America, search remained "immature" but closely related to the

Jan 1, 1997

By Basil S. Fee

INTRODUCTION Probably the most important family of chemicals used in mineral processing today is a category of basic commodity chemicals loosely denoted as pH regulators. Typical chemicals which are referred to as pH regulators include lime, magnesium hydroxide, soda ash, caustic soda, ammonia, sulfuric acid, and hydrochloric acid. These chemicals are often used in very significant amounts in almost all of the major mineral processing operations such as flotation, hydrometallurgy, etc. (in dosages up to ten pounds per ton of feed ore treated). While cheaper in cost per unit weight of chemical than more specific chemicals such as collectors, frothers, extractents, etc., the overall cost to the mill operator is generally higher with pH regulators per ton of ore processed than with any other given processing chemical. For example, a rough rule of thumb in sulfide mineral flotation is that the cost of lime is double that of the collector(s) used. The symbol pH is used to designate hydrogen ion concentration. When acids, salts, and bases are dissolved in water, individual molecules are dissociated into their constituent radicals or ions. The strength of an acid or a base increases with the extent of such dissociation or ionization. An alkaline solution is one in which the number of Qydroxyl ions (OH ) exceeds the hydrogen ions (H ). In an acid solution, the hydrogen ions predominate. In either case, both ions are always present as water itself ionizes to a limited extent, that is: [ ] The pH scale is logarithmic and the pH value is the negative of the logarithm (base 10) of the molar concentration of hydrogen ions per liter of solution. For example, a pH of 5 means that the molar concentration of hydrogen ions per liter is 0.00001 (1 x 10-5). Likewise, a pH of 9 means that the molar concentration of hydrogen ions per liter is 1 x 10-9. Normally, the relationship between hydrogen ion and hydroxyl ion concentration is based on the relationship: Concentration of H ion x concentration of OH- ion = constant. Eq. (1) In dilute and/or moderately concentrated solutions that are normally used in mineral procygsing processes, the constant at 25°C is 10-14. On the pH scale, the value of pH equal to 7 represents the hydrogen ion concentration of a neutral solution. pH values lower than pH 7 indicate increasing acidity and higher values than 7 indicate alkalinity. Table 1 shows the nature of the pH scale at 25°C. Temperature affects the extent of ionization of dissolved acids, salts, bases, and water so that the hydrogen ion concentration (hence pH) of a solution is also affected by temperature. As a means of demonstrating this dependency, Table 2 shows the change of the exponent of the constant (base 10) in Eq. 1 and the pH value corresponding to neutrality as a function of temperature. It is also important, for example, that alkalinity or acidity expressed by pH not be confused with total alkalinity or total acidity. For example, total alkalinity is commonly determined by titration with a standard acid solution (usually HC1). pH is a measure of the hydroxyl ion concentration of an alkaline solution, whereas titration is a measure of an alkaline solution's acid neutralizing capacity. Thus, if one takes a series of various alkaline solutions prepared using different chemicals but all of exactly the same pH (and temperature) and then subsequently carries out a titration on each solution with a standard acid, it would be observed that the various alkaline solutions would neutralize entirely different amounts of acid. As an example, 0.08 grams of caustic (NaOH) , 6.32 grams of soda ash (Na2CO3), and 8.17 grams of ammonium hydroxide (NH4OH) all have a pH of 11.3 at 25°C. One liter of each of the above solutions neutralizes 0.073, 4.348 and 8.496 grams of HC1, respectively. Therefore, depending on the specific use of any given pH regulator, special tests need to be run by the mill operator to determine factors such as: the specific technical goals to be accomplished by

Jan 1, 1986

By W. C. Wheeler, G. Suranyi, J. F. Gentleman, J. Muller, R. Kusiak

INTRODUCTION In 1974 two of the present authors reported the results of a pilot study indicating an increase of lung cancer risk in Ontario uranium miners. (Muller, Wheeler, 1973, 1974) The study was based on data contained in a computerized Mining Master File maintained by the Ontario Workmen's Compensation Board that contained information on miners examined in Ontario who had either 60 months of dust exposure in mines or had signs of pneumoconiosis or tuberculosis. Including the above conditions the definition of uranium miners added the condition of one month or more of uranium mining experience in Ontario. This list of Ontario uranium miners contained 8,649 names. Following the results of this first pilot study, we embarked on creating a file of uranium miners containing information on men with one month or more of uranium mining experience in Ontario without any further conditions. This file was used by the Royal Commission on the Health and Safety of Workers in Mines in their study of risk in Ontario uranium miners. (Hewitt 1976) This file contained 15,094 names. In this report we give an outline and progress report on a study of Ontario miners that we are conducting at present. It was felt that the male population of Ontario is not necessarily an adequate control population for uranium miners. A preliminary examination of the work history of uranium miners indicated that the majority of them (about 90 percent) had other mining experience in addition to their exposure in uranium mines. We therefore considered it useful to evaluate the possible effects of non-uranium mining on risk, and for this reason decided to make the Uranium Miners Study part of a study dealing with the mortality of Ontario miners in general. Aims of the Study The aims of the Study include the evaluation of: 1) the risk of dying by cause in non-uranium miners as compared to the male population of Ontario and Northern Ontario. 2) any differences that might exist in the death experience of non-uranium miners by cause according to ore mined. 3) the effect of length of exposure in non-uranium mines on age-specific risk by cause. 4) the dose-response function for primary cancer of the trachea, bronchus and lung from exposure to radon and its short-lived daughters. 5) the possible effect of the mining environment on deaths from causes other than cancer of the trachea, bronchus and lung. The study will address itself to a number of other factors that might well affect the dose-response function. These include: a) factors in the mine environment - other than radon daughters - that might affect lung cancer mortality. b) the effect of non-uranium mining on lung cancer risk in uranium miners. c) the effect of age as well as age at time of exposure on lung cancer risk. d) questions of latency and the possible dependence of latency on age at time of exposure. e) smoking as an important factor in lung cancer risk. f) Histological type of cancer in relation to the various parameters of exposure and age. MATERIALS AND METHODS The Study is making use of existing computerized data files and has set up certain new files. These include the Mining Master File and the Model Development File. The Mining Master File This file is a computerized record of data on individual miners obtained at yearly miners' examinations that have been carried out since the mid 1920's. The conditions for inclusion in the Mining Master File have been indicated above. Information contained in the file includes: (1) Identifying information: a) Surname and given names b) Date and place of birth c) Miners Certificate Number d) Social Insurance Number if available. (2) Updated Employment data obtained at each miner's examination: a) Year of first dust exposure in Ontario b) Year of first dust exposure outside Ontario c) Number of months worked in mining d) Ores mined e) Mining areas and mines f) Occupations

Jan 1, 1981

By Maria S. Adusmilli, Bhaskara A. Rao, Jorge G. C. Barros, Augusto F. Mendonca

Lateritic gold has been the object of study only for a very few years, though nuggets have been mentioned in earlier works even as early as 1984 by Hartt in Brazil. In Mato Grosso State, lateritisation is intense, as is common in all tropical forest areas of the world. Exploration has revealed the presence of recoverable "nugget gold" of variable sizes (30 - 200 gms) but frequently of good size (0 - 40 gms), especially near Cuiaba and Alta Floresta regions. In both of them the host system is a lateritised breccia indicative of a fault or shear zone breccia, though in different lithological domains. The Cuiaba occurrences are phyllitic and show a profile as follows, from top to bottom: 1) Compact ferralite crust. 2) Oolitic to pisolitic compact crust (+ some gold). 3) Mottled concretionary laterite crust. 4) Lateritised "eluvial material" (gold nuggets). 5) Mottled patchy to banded laterite. 6) Banded lateritised phyllite with lenticular to banded goethite. 7) Altered red goethitic phyllite, with quartz veins (+ fine gold). 8) Unaltered grey phyllite with quartz veins (Protore). The Alta Floresta-Juruena River occurrences are volcano-sedimentary and show a profile as follows: 1) Deep brown siltitic, argillaceous and arenaceous material with organic matter (+ gold). 2) Modular and concretionary laterite, compact and indurated, with arsenophyrite in quartz fragments (gold nuggets). 3) Band with silty-clayey matrix and arenaceous in nature. 4) Bedrock meta-arcosian arenite. 5) Volcano-sedimentary with rhyodacites and andesitic basalts, with intercalations of arkosic and greywacke nature. Breccias and quartz veins, and granites associated in different portions (Protore).

Jan 1, 1988

By K. Mulukhov

Introduction The depth of open-pit mines continues to increase. The typical designed depth for large quarries is now in the 300 to 600 m (1,000 to 2,000 ft) range, with some quarries even reaching depths of 700 to 800 m (2,300 to 2,600 ft). The cost of handling material from such deep mines can be 60% to 70% of the total cost. The capacity of using a cyclic means of transport, such as trucks or skip hoists, continues to drop as the depth of the mine increases. In addition to the problem of maintaining relatively low slope angles for haul roads, increases in environment pollution and increased fuel consumption make the use of trucks ineffective below 100 to 150 m (300 to 500 ft). In handling large quantities of bulky materials, i.e., more than 15 to 20 Mt/a (16 to 22 million stpy), under fixed terminal points, belt conveyors are preferable in almost in all cases. An exception is when the lump size of the load is too high for the conveyor to handle. Belt conveyors in mines can handle loads having a maximum lump size of no more than 250 to 300 mm (10 to 12 in.). The use of a movable crusher prior to the belt conveyor in an open-pit mine would make the process very expensive. Such an operation could not compete with truck haulage on a cost basis. Belt-car conveyor The main factor that restricts the lump size for conventional belt conveyors is collision impacts between the load-carrying belt and idlers. These impacts are completely eliminated in the belt-car conveyor, which was previously described by Mulukhov (1977). The unique feature of the conveyor is that the load-carrying belt is supported by moving cars. Each car consists of a troughed cross strap that supports the belt with the load and two rollers, on which the cars move along upper and lower rails. Cars are connected by two endless chains revolving over sprockets. The system uses conventional drive pulleys, tail pulleys and return idlers. There are no fasteners between the carrying belt and the car cross straps. The conveyor belt simply drives the cars along by the force of friction between the belt and the straps. A belt-car conveyor was first installed in 1970 at the Karatau mining operation in Kazakhstan. The system was an elevating conveyor with an inclination of 20° and was located on the final part of the truck haul road. The conveyor transferred blasting phosphate ore from the quarry to the crushing plant. A bunker was mounted between the trucks and the conveyor. The maximum lump size was typically 1,200 mm (48 in.). However, there were some lumps as large as 1,500mm (60 in.), which was greater than even the belt width (Fig. 1). Because the prototype belt-car conveyor was intended only for industrial trails, it had a relatively short length of about 50 m (160 ft). Nevertheless, the conveyor yielded a substantial profit over the cost of truck haulage. Naturally, the first question one might ask is why such a system is not now widely used. The reason was the further development of a huge transporting complex for the whole quarry at the base of the belt-car conveyor. After successful industrial trials from 1971 through 1973, which demonstrated the systems engineering feasibility, the State Planning Committee of the USSR included the development of the belt-car conveyor in its plan for the development of the national economy. However, mistakes were made. First, a single organization was not in charge of the development. Second, a plant that was not specialized in belt conveyors was put in charge of the design and manufacturing of the conveyor system. In addition, the crusher was installed before the stacker, which negated the major advantages of the belt-car conveyor. For loading the conveyor, a special blade feeder with pendulum suspension was developed, but it was found unreliable. The main conclusion was that, in-

Jan 1, 2003

By David P. Keller, George Podolsky

Iron oxides are unique in that they are the only significant colored mineral found in a natural state suitable for use as a pigment after being pulverized to pigmentary size. The world production of iron oxide pigments is estimated by the authors to be between 350 and 400 kt. The fact that highly colored natural deposits of iron ore are found throughout the world accounts for its use in prehistoric man's artistic cave paintings. These early artists did not realize that they had established man's first paint test which now has some 20,000 years of exposure. In addition to abundance, iron oxides (about 7% of the earth's crust) have the advantage of low cost, permanency, and are non- toxic. Through the centuries, succeeding civilizations have utilized iron oxides as a major source for decoration and protection when these properties were desired. In the last century the chemical industry has improved on nature by developing a complete range of synthetic iron oxide pigments which surpass the pigments produced from natural iron ores in uniformity, color quality, and chemical purity. In the United States, the combined production of natural and synthetic iron oxides produced sales of over $97 million in 1980 (Spimad, Jr., 1980), increasing to $138 million by 1990 (Templeton, 1990) NOMENCLATURE With the increasing importance of the synthetic iron oxides it is necessary to make a distinction between the natural or mineral pigments and the synthetic pigments. Natural pigments are those products that are derived from selected ores and should not be confused with iron ores mined for steel production. Iron ores that are mined for steel must be capable of being mined and reduced to iron on a competitive commercial basis. These ores are selected on the basis of iron content and processing economics. It is therefore unusual when iron ores for steel production are suitable for use as mineral pigments. Natural pigment ore sources are selected for their special physical-chemical properties and are able to command a premium price over iron ores used for steel manufacturing. Synthetic pigments, and in this instance iron oxides, are those pigments produced from basic chemicals. Through chemical synthesis pigmentary particles are produced as opposed to the use of comminution, the major procedure common to all natural iron oxide pigments.

Jan 1, 1994

By Dale R. Ralston, Roy E. Williams, Gerry V. Winter, George L. Bloomsburg

GENERAL HYDROLOGIC REGIME The total hydrologic cycle must be considered when evaluating potential ground water problems in a mining environment. Precipitation is the ul¬timate source of all surface water and essentially all ground water. Stream flow during low flow periods often orig¬inates as seeps or stream gains (base flow) where the water table intersects the land surface. A stream that is higher in elevation than the ground water system may lose flow, thereby recharging the ground water system. The magnitude of stream gain or loss is dependent upon the hydraulic conductiv¬ity and related properties of the underlying hydrostratigraphic units. Ground water moves constantly from recharge areas to discharge areas (streams and springs) usually at very slow rates. Large quantities of ground water may be in¬tercepted in many underground mining environ¬ments. Construction of an underground mine in saturated formations may encounter ground water inflows ranging from very small to very large and from continuous to intermittent depending upon the hydraulic properties of the hydrostratigraphic units penetrated. SURFACE WATER VARIABLES Precipitation occurs in different forms, varying amounts, and with a wide assortment of temporal and areal distributions in the various mining dis¬tricts within the United States. Mine inflow can be affected in a matter of hours by precipitation events where there is a direct hydraulic interconnection between the mine and the surface through fractures or a mine opening. The timing, form, amount, and distribution of precipitation should be evaluated in a mine inflow study. A portion of the precipitation that falls in a topographic basin moves as sheet flow to runoff channels (Fig. 1). Some of the precipitation infil¬trates the unsaturated soil zone where it can either move laterally as interflow to the surface system to augment stream flow or move downward as re¬-charge to the ground water system. The unsatu¬rated zone (called the zone of aeration or vadose zone) can range in thickness from essentially zero to a few hundred feet. The saturated zone or ground water system occurs below the water table (zone where hydrostatic pressure is greater than atmos¬pheric pressure) where all the pores are filled with water (Freeze and Cherry, 1979, p. 44). Moisture can be lost from any of the systems (surface water system, unsaturated zone, and ground water sys¬tem) by the processes of evaporation and transpir¬ation which return moisture to the atmosphere. Stream flow consists of runoff and interflow components plus an additional base flow compo¬nent (Fig. 2). Base flow constitutes ground water discharge to a stream. Base flow plays an increas¬ingly significant role as total stream flow declines. Base flow is important because it constitutes much if not all stream flow between periods of precipi¬tation when runoff and interflow have largely dis¬sipated. INTERACTION OF SURFACE WATER AND GROUND WATER SYSTEMS Recharge from a surface water system to ground water systems can occur via unsaturated or saturated flow. The amount of recharge is depen¬dent primarily upon the vertical hydraulic conduc¬tivity of the formations underlying the stream and the availability of water. Streams that flow over low hydraulic conductivity formations lose little water even if the ground water levels are significantly lower than the stream. A ground water system may contribute flow to a surface water system but nor¬mally only by saturated flow. This contribution usually takes the form of seeps, springs, and the base flow of streams. GROUND WATER VARIABLES Introduction The variables that affect ground water flow are discussed in increasingly complex theoretical situ-

Jan 1, 1986

By Roger A. Kauffman, Dean Van Dyk

Feldspar is the earth's most abundant mineral group. The feldspars are aluminum silicate minerals belonging to the tectosilicate class. Feldspars are the most widespread of any mineral group and are estimated to constitute 60% of the earth's crust. They make up a large percentage of the exposed rocks as well as soils, clays, and other unconsolidated sediments. Feldspars are widely used in the glass and ceramic industry and are principal components in rock classification schemes. Feldspar minerals and their production are important contributors to the domestic and world economies and standard of living. In 1990, the United States produced 630 kt of feldspar minerals, and world production was estimated to be more than 5 Mt. Feldspar mineral production in the United States has a long and interesting history (Feitler, 1967, Rogers Jr. et al., 1983). The first commercial production in the United States occurred in about 1825 and came from pegmatite bodies located in Connecticut, where feldspar was mined, hand sorted, and shipped to England. Feldspar production grew during the 19th and 20th centuries with important developments in production location, integrated mine and processing facilities, and the development of the flotation process for feldspar by the US Bureau of Mines and the feldspar industry. The first commercial feldspar flotation plant began operations-in Kona, NC, in 1946, some six years after this process had been developed. In 1990, the domestic feldspar industry consisted of 12 operating companies with mines and processing plants located throughout the United States (see Table 1). During the last 25 years, the domestic feldspar industry has been dynamic, marked by new plant construction and capacity expansion at older plants. The industry has also seen plant closures, changes in ownership of existing operations, the consolidation of the Canadian nepheline syenite industry, and the increase of imported feldspar products. The industry has been affected by contractions in its major end-use markets brought about by economic cycles, product substitution, and environmental effects, such as recycling, land-use controversy, and air and water pollution. Despite problems, the industry remains mature and highly competitive. GEOLOGY Mineralogy The common feldspar group of minerals form a single crystalline phase or solid solution series of minerals. Fig. 1 is a ternary phase diagram that shows the feldspar mineralogy-KAlSi,O8, NaAlSi3O8, and CaAl2Si2O8. The end-member compositions are also referred to as potassium, sodium, and calcium feldspar. The feldspars whose chemistry ranges between the potassium and sodium end-members are known as alkali feldspars, while those between the sodium and calcium end-members are plagioclase feldspars. These feldspar groups can be further subdivided based on structural and compositional features within the alkali or plagioclase feldspar series. The distinction between and the proportion of members of the two feldspar groups are important to the classification of igneous rocks (Deer et al., 1966). Perthites are the exsolution product of an initially homogeneous potassium-sodium feldspar solid solution which forms (in an environment of decreasing temperature) a heterogeneous intergrowth of sodium-rich feldspar lamellae in a host crystal of potassium feldspar. Antiperthites are exsolution products in which the host mineral is sodium-rich plagioclase feldspar and the intergrowths are potassium-rich feldspar.

Jan 1, 1994

By Klimpel. R. R.

Acknowledgments I am honored to be named as a recipient of the Antoine M. Gaudin Award, and I would like to briefly single out four groups who deserve a special thank-you relative to this award. The first group consists of Professor Kawatra, the many international support references that he gathered and the Gaudin Committee itself. I know such things don't come without considerable effort by many individuals, and I'm grateful for their support. The second group consists of the management of The Dow Chemical Company, the managements of various mining companies and, in recent years, the management of G. S. Technologies, all of whom supported me, financially and otherwise, in my grinding, flotation and other particle-processing work. Operations people are the most overworked and under recognized people in the world, whether they be in the mining or chemical industry. Obviously, without extensive industrial support, especially from operating personnel in the mining industry, almost nothing about the work contained in this lecture would have, or could have, happened. The third group consists of a number of coworkers who have played key roles in specifically implementing the new flotation-product portion of this lecture. Of these, Bob Hansen, Don Leonard, Basil Fee, Simon Isherwood, Fernando Cones and Marty Meulendyke deserve special recognition. They have not only been dedicated, but they have been great to work with. Also in this third group are many members of the international academic community, especially those at Penn State. Professor Leonard Austin must be singled out because he took me as a young mathematically oriented chemist and taught me to be an effective process-oriented engineer. Without this experience, I would not have had the over 30-year career as an engineer, which I have loved. In addition, Len planted the size-reduction-research virus in my blood, which I can't seem to get rid of. I also need to mention Professor Frank Aplan, whose obvious love of mineral processing and froth flotation helped to create my interest in flotation. Thus, for those of you who don't like my approach to flotation, it's all Frank's fault. The fourth, and certainly not the least, group to thank is my wife, Charlene, and our two sons, Richard and Steven. No one could have a more supportive family. In every sense of the word, my wife has been my partner from the beginningwe were married at the end of my freshman year in college. She has sacrificed much for me, and I will never really be able to express the depth of my gratitude for Charlene's encouragement, loyalty and support over the past 36 years. General comments on froth flotation The industrial process of froth flotation: Where is it going? I'm here to tell you loud and clear that froth flotation is alive, well, and growing. The inherent characteristics of high mineral throughput per unit of capital, low operating cost per unit of feed, high mineral specificity and high operating flexibility have guaranteed froth flotation an important past and a growing future. As with any evolving technology, there are always trends at the industrial level that are primarily driven by economics. The current trends include: •the movement towards larger and larger equipment, •more alternative equipment designs (e.g., the column cell),

Jan 1, 1996

By Andrzej Frycz

The development of the theory of reliability creates more and more possibilities of its application in different domains of technics. The methods evolved to date, both theoretical analysis of the engineering systems and investigations techniques in practice can be put in use a d translated from one science to another one [1,3,7J . It needs to consider the specific of the different sciences. But it is necessary to take account of the specific characteristic of each line of science. The reliability investigations needs, justified in technical and economical viewpoint appear too in mine ventilation technics and systems. The mine ventilation system is a complex of workings and ventilation plants, which serve to supply the networks with a sufficient quantity of fresh air from the atmosphere and then carry off the vitiated air. The condition necessary for a ventilation system to perform definite task is the correctness of all its elements, that is a capability to preserve in a expected range of tolerance, the values of basic parameters. The element of a system which ceases to work correctly is called failed. The basic parameter of all elements of a ventilation system is the characteristic curve, pressure loss - air quantity relation ?p = f(Q) (1) This curve concerning the workings and ventilation stoppings is given by the formula: ?p = R Q2 (2) thus the resistance R (of the workings or stoppings) may be taken as a characteristic parameter. The course of this characteristic f(Q) will be given in a complex form in concern with fans, ejectors, air curtains. The failure of a ventilation plant or working is therefore an event, relying on a change of its characteristic, thus for a definite time the losses of the plant's or working's capability set in for the fulfilment of its function in the ventilation system. The failures are divided in viewpoint of their nature on sudden and progressive. We are in concern with the sudden failures which are characterised by a violent change of the ventilation element parameter for example a fall of roof, or silt up of the working, opening or failure of the ventilation stopping, the stand-off of the fan or ejector etc. We distinguish two kinds of failures on the viewpoint of their action on the air flow: the "opening" failure and "closure" failure. The prevalence of factors, which causes the failures is in connection with the intersection in the mine of roads of haulage, roads of underground transport of materials and lining elements, roads of people motion with airways, as also depends on the rock pressure reaction on the workings lining and plants placed there. Other factors will yet be decisive upon supply decay of fans, ejectors and curtains. The appearance of failure of the ventilation element is therefore of random nature and determines the change of the element, when it is passing from operating state to unoperate. Qualifying the ventilation system element to one of these states is easy, when the characteristic change is clear and occurs suddenly, that was assumed. The investigations conducted by Patrushev and Karnaukh [91 in concern with the ventilation stoppings resistance change in the case of their opening, had shown the possibility of resistance value change in the range of several hundreds higher.

Jan 1, 1980

By S. C. Westerfeld

The original patent for the gyratory crusher was granted to Philetus W. Gates in 1881. This first crusher was used by the Buffalo Cement Co. At the time these early gyratory crushers were developed all mining and quarrying, either underground or open pit, was done by hand; tonnages generally were small and product specifications simple and liberal. Likewise plants were small and demands for small product sizes practically nonexistent. In addition to substantial amounts of hand labor, the available material handling equipment was small, simple, and not suited to handling large run of mine ore. Mine can, cable ways, or belt conveyon transporting crushed material to the mill had limited capacity per hour. At the turn of the century the largest Gates crusher, the No. 9, had a receiving opening of 21 x 48 in. with a three-arm spider and a 21 x 80-in. opening with a two-arm spider. The steam shovel began to change the entire picture of open pit quarrying. As a result of the use of steam shovels around 1910 crushers with 48-in. receiving openings were built; thus it can be seen that the basic gyratory crusher was developed prior to World War I. The improvement of the internal combustion engine and the use of pneumatic tires created a new set of operating conditions. Early mines were small, using shrinkage stoping and small mine can. The capacity of material handling was small, limiting the size of the largest piece and the feed rate. Improved material handling resulted in more and more large open pit mines with large shovels and a tremendous increase in the size of off road or mine haul trucks or rail can. Primary gyratory crushers also increased with receiving openings as large as 60 in. and connected hp of 1,000.

Jan 1, 1985

By John T. MacWaters, George H. Milly

INTRODUCTION This paper describes operational procedures and instrumentation which were developed to implement a patented method of detecting and locating uranium ore bodies. All equipment was designed for accurate and reliable use under difficult field conditions. Data resulting from these developments, some of which are incorporated in a companion paper for this conference*, have contributed to our understanding, of the nature and significance of naturally-occurring radon exposures. Further applications of these techniques may prove useful in studying anthropogenic radon in evaluating the significance of variability in radon flux, or in taking proper account of the contribution of natural radon to ambient radon concentrations, particularly in mineralized regions. OPERATIONAL PROCEDURES The uranium search technique employed by GEOMET begins with a [reconnaissance mode], which utilizes a series of ambient air filter samples taken from a moving or standing vehicle to detect anamalous concentrations of radon. These samples are normally taken at night under stable (temperature inversion) or neutral atmospheric conditions, to avoid the rapid dispersion of the radon clouds typical of daytime turbulent conditions. Radon daughters formed by the decay of radon quickly attach to ambient aerosol particles and are captured on the surface of a membrane filter during a five-minute sampling period. The filter is placed in a portable alpha scintillation counter, and a five-minute count is started at a preset time after the completion of the sampling period. This count is followed immediately by a second five-minute count to enable determination of the cloud age, based on consideration of the relative half-lives of the initial radon daughters. With the use of tables computed from the mathematics of the uranium decay process, and with the measured radon background accounted for, the first and second counts are used to estimate the time which has elapsed since the pure radon initially emanated from the earth's surface. This cloud age, combined with wind speed and direction measurements made at the beginning and end of each sample, as well as with an understanding of the effects of local terrain features on wind trajectory, provides an estimate of the Probable location of the source. In practice the reconnaissance mode involves one vehicle with a single operator to take the five-minute samples, moving or standing, along any available roads or trails in the area to be covered. Under the usual nighttime stable conditions the cool air flows downslope and downvalley, and the operator will pay special attention to locations along the axes and confluences of the natural downflow patterns. These facilitate sampling of large air drainage areas. Successful detection of sources of radon based on high concentrations of radon daughters, and substantiated by evidence of "fresh" clouds, are frequently made on the basis of a relatively few samples taken judiciously by an experienced operator during a reconnaissance. At this point he has a choice: he can continue to cover the designated reconnaissance area, leaving the localization of any anomalous radon detections to await the ranking of detections by priority, or he can continue with localization of the detected source, either alone or by radioing for another vehicle to assist in triangulation operations. Localization of a source involves skillful and experienced use of the continuously collected data on concentration, age, and wind speed and direction, together with knowledge of the terrain from observation and contour maps, and exploitation of the available roads. Since age ratios are dependent solely on proximity of the source and wind speed, decreasing [cloud ages] based on statistically significant increasing age ratios represent the most useful. information in localization. The [magnitude of the concentration] of radon daughter products is also useful; however, it may vary widely for a variety of reasons during sampling for a localization, thus making this a secondary parameter for localization. Large values of concentration are of course useful; typical results for successful detection of a strong anomaly would yield alpha counts ranging from 10 to 25 times background values. These counts are convertible to ambient radon concentrations by appropriate consideration of the decay process. Successful localizations of radon sources using this procedure with ambient atmospheric measurements normally will narrow a source location to within an area ranging in size from less than a quarter of a square mile to at most a square mile, and frequently give information on the probable shape of the source (in plan view) on the earth's surface. Judicious use of this procedure could undoubtedly provide finer localization, but the coarser results just described are adequate for this Phase of GEOMET's uranium exploration procedures.

Jan 1, 1981

By Geoffrey Purcell

The flotation response to amine collector of quartz and the feldspars microcline and albite, of the pyroxenes augite and spodumene, and of olivine can be, explained by a physical adsorption model. Flotation decreases in the order given above, and the different behavior of the three groups is attributed to structural variations of the silicates, With sulfonate collector both chemical action and physical adsorption play their part in producing hydrophobic surfaces, and flotation increases in the order given.

Jan 1, 1966

By W. Robert Power

Stone is considered by many to be the premium material for beauty and durability in all kinds of construction. Its use dates to the dawn of civilization and only buildings made of stone have survived from ancient times. The use of stone relative to other materials declined from the beginning of the present century reaching a low point in the third quarter, but there has been a resurgence in the use of stone in construction during the past decade, due probably, to new techniques for producing stone, a greater recognition of its beauty and durability, and greater affluence among consumers. The aesthetic appeal of stone is attested to by the many attempts to simulate it in synthetic materials. Today, natural stone is considered by many to be the ultimate in aesthetic appeal, durability, and ease of maintenance. Consumption of dimension stone has increased dramatically during the past decade. The US Bureau of Mines reported that the total value of US consumption in 1978 was $1 13 million and that total imports were valued at $65 million in 1979 (Anon., 1980). In 1989 consumption of domestic dimension stone was valued at $208.3 million and imports at $525 million. This dramatic increase occurred after demand had decreased at an average rate of 2.5% in the two decades prior to 1978 (Anon., 1980). More than half of the imports come from Italy, but production of dimension stone has increased worldwide spectacularly. Meaningful statistics on dimension stone are hard to acquire. The finished piece of stone is a highly value-added product, but stone may be sold as rough blocks, sawed slabs, or finished product. The same piece of stone may therefore be sold and reported three or more times. Furthermore, although the quantity of stone is most commonly reported in tons, stone cladding is more often sold by the surface area and at the same price for different thicknesses. By any measure, however, the production and consumption of dimension stone has increased dramatically during the past decade. A significant indication of the resurgence of stone was the introduction of two new trade publications during the 1980s. Stone World (Tradelink Publishing Co., Inc., Oradell, NJ), introduced in 1984 is published monthly and Dimensional Stone (Dimensional Stone Institute, Inc., Woodland Hills, CA), introduced in 1985 is published monthly. Both magazines provide useful information on new technology, market trends, producing areas and companies, and other information not previously available.

Jan 1, 1994

By David A. Lindsey

In this paper, we present a physiographic classification of gravel deposits, identify some field measures of aggregate quality, and describe sampling strategies for mapping aggregate quality in the Front Range Urban Corridor of Colorado. Gravel occurs in four types of deposits along the Front Range of Colorado: (1) piedmont alluvial fans, (2) high dissected terraces, (3) high (continuous) terraces, and (4) floodplains and low terraces. The four deposit types are the basis for definition of gravel-deposit models, which differ in geologic environment, deposit characteristics, deposit size, environmental impacts of mining, and post-mining use. Of the four types, floodplains and low-terrace deposits have been exploited most for gravel. High terraces also have been mined. Deposits of high dissected terraces and dissected alluvial fans have produced minor amounts of gravel, mostly for use as local fill. Studies to identify useful field measures of aggregate quality and to determine the appropriate scale for sampling were conducted on gravel deposits beneath the flood-plain and low terraces of the South Platte River north of Denver and the Cache la Poudre River between Ft. Collins and Greeley. Gravel deposits of the South Platte were selected for study because they represent the last major resource of gravel for aggregate in the Denver metropolitan area. The Cache la Poudre valley is the primary source of gravel aggregate for rapidly urbanizing areas around Ft. Collins and Greeley. Of all the field measures of gravel quality, the most important is particle size. Various parameters that measure particle size were investigated, but the easiest to determine, and the most useful to the aggregate industry, are measures of the proportion of coarse sizes. Particle size varies widely in gravels of the urban corridor. Gravel lithology, particularly the presence of deleterious particles such as reactive volcanic rocks and decomposed rocks, must be determined to assess aggregate quality. Studies of South Platte and Cache la Poudre gravels have not revealed large proportions of deleterious lithologies. Studies of particle shape revealed only small numbers of physically weak shapes in both the South Platte and Cache la Poudre gravels. Particle shape does not appear to vary from place to place in the gravels. Rounding, or the ab¬sence of angular corners, may play a role in the tendency of loose gravel to yield under load. South Platte and Cache la Poudre gravels are rounded, and rounding tends to increase upstream. Before the quality of gravel in a valley can be assessed, the stratigraphy of the gravel must be known because it affects sample design. If only a single gravel layer is to be studied, only the thickness of the gravel must be known before sampling. If, however, more than one layer of gravel-distinguished by particle size, sorting, or lithology-is present, sampling must take into account the thickness and distribution of each layer. For example, three gravel layers of different particle size underlie the floodplain and low terraces of the South Platte. The tributary Cache la Poudre, on the other hand, contains gravel layers that can be distinguished only locally and vary slightly in particle size. Sampling experiments were conducted on gravel bars in the South Platte River and in gravel pits on the floodplain and low terraces of the South Platte and Cache la Poudre Rivers. Experimental results indicate that, even where sample error is large, regional and stratigraphic variation may be measured if it is large relative to sample error. Using vertical trench samples weighing an average of 40-90 pounds, down-stream decrease in coarse particle size was mapped for Cache la Poudre gravel, and differences among superposed gravel beds were measured for South Platte gravel.

Jan 1, 1999

By Gordon M. Pugh, David G. Rasmussen

INTRODUCTION Shrinkage stope mining can be employed in steeply dipping veins where both the wall and the vein material are sufficiently strong to stand with only minimal ground support. Shrinkage stope mining takes advantage of the swell in volume produced in breaking in-place ore. This expanded volume of ore is allowed to occupy part of the mined-out vein, and in so doing provides ground sup¬port and a working surface for the miners. Only enough of the ore is drawn after each stoping cut to allow work¬ing room. Not until the entire mining block has been broken is the full amount of broken ore drawn from the stope. DEVELOPMENT PRACTICES FOR SHRINKAGE STOPING The vein is developed into stoping blocks, each of which is 76 to 91 m (250 to 300 ft) in length and 61 m (200 ft) between levels. Level development, described later, is either on the vein or parallel to it with crosscuts periodically driven over to the vein. There are usually two exits from each stope. The first entry is a raise at one end driven either conventionally by raise climber, or by a raised borehole. Present practice is that this raise, put in from level to level, is either a 2.1- x 2.1-m (7- x 7-ft) Alimak raise or a 1.2- to 1.8-m (4- to 6-ft) diam borehole. Either raise system will require pro¬visions for an ore chute carried with the stope to the haulage level or the scram drift. At 9- to 12-m (30- to 40-ft) vertical intervals, dogholes are developed from the raise so that when stoping breaks back into these dogholes, timber or steel sets and necessary service facilities can be installed. The second entry to the stope may be either a similar raise at the stope endline, or more economically, a cribbed raise carried with the stope. As previously stated, development of the ore block is achieved by either drifting on the vein or by paralleling the vein with a footwall lateral and then crosscutting over to the vein at specified intervals. In the following discussion, three basic cases are illustrated in Figs. 1, 2, and 3. In Fig. 1, development is in the footwall by a 3- x 3-m (10- x 10-ft) trackless lateral. A heading is also driven on the ore and taken either full width or driven a standard size and slabbed to the vein width. Approxi¬mately 9-m (30-ft) long crosscuts on 7.6-m (25-ft) cen¬ters are driven from the lateral to the vein. For ease in muck handling they are usually put in on a slant rather than at right angles. A single orepass, located off the lateral and in the center of one stope block, can serve not only that stope, but also one on either side, up to a tramming distance of not more than 137 m (450 ft). Raises are put at the stope endlines on 91-m (300-ft) centers. The back of the vein is shot down and just enough broken material is drawn off to permit access for men to work off the broken ore. Development in Fig. 2 progresses by driving a 3- x 3-m (10- x 10-ft) trackless heading on the footwall side of the vein. The ore block is delineated by raises on 91-m (300-ft) centers. Crosscuts are again driven on 7.6-m (25-ft) centers over to the vein. Approximately four rounds are then taken up to the vein and each round is successively belled out so that all the crosscuts (pockets, in this case) connect. In this development, as opposed to that in Fig. 1 where there were no belled

Jan 1, 1982

By Prasad S. Mulukutla

INTRODUCTION The use of specialty chemicals In mining Is an Important consideration In determining the economic efficiency of a floatation plant. The plant metallurgist would like to maximize the recovery of valuable minerals while maintaining an acceptable grade product. The direct cost of the reagents, while significant, Is only a part of their economic effect. Reagents determine the flotation rates and the selectivity of the mineral separation. In flotation practice, mineral selectivity can be achieved through the addition of various reagents that can control the wettablllty of a particular mineral In the flotation pulp. The reagents which will generally optimize the flotation process are commonly classified Into three distinctive categories: collectors frothers and modifiers. Large tonnages of metal sulphide concentrates which are the source of most of the common base metals are produced economically by fairly standard flotation techniques. The advent of modern technology coupled with the necessity of processing finely disseminated and complex ores of low grade has Increased the need for utilization of non traditional and high selective chemicals reagents for the economic recovery of metals and raw materials. Mining operations in developing countries continue to progress at a rapid growth as many countries mine and process both metallic and nonmetallic ores. The total mine production of base metals, precious metals, Iron ores and coal In developing countries In Africa, Asia and South America has been much higher as compared to the western world production In terms of tonnage and dollar value. Global capital Investments In mining during 1991-95 Is $ 55.1 billion and It Is anticipated that the development of new and specialty reagents may be concentrated In the processing of aluminum , copper, precious metals and Industrial minerals with special reference to potash, phosphates, kaolin and silica sands.(1) The challenge for the design and development of new specialty chemicals Is dependent on Its cost performance and environmental acceptability. Information on the theory and application on the development of mining chemicals has been reviewed In several conference proceedlngs,(2-4) publications(5) and also discussed by several Individual authors.(1,6-10) These publications serve as a comprehensive reference source on the reagents used In several flotation processes. This paper discusses the present trend in the use of specialty mining chemicals In diversified mining operations on several mineral systems with particular reference to sulfide ore systems. The necessity to expose these specialty chemicals through aggressive marketing techniques In mining operations In many developing countries Is also presented. SPECIALTY CHEMICALS Specialty mining chemicals, like other specialty chemicals, share common business characteristics that transcend geographic boundaries. They are manufactured 1n a few selected areas, generally expensive relative to commodity chemicals, shipped and compete globally and usually require specialized knowledge for proper use. Specialty mining chemicals are relative newcomers to chemical markets. The vast majority of mining chemicals are derived from products that are less than two decades old. Traditional collectors and frothers have been available for a considerably longer time. The emphasis on adding value to existing products and byproducts Is responsible for several characteristic features of the mining chemicals business. Most raw materials for these chemicals are related to oil and gas byproducts, chemical refineries, pulp and paper mills and all chemical manufacturers. Until the last several years these operations were located In Industrialized countries, while a significant number of mining chemical users were In developing countries. Therefore International trade In mining chemicals developed through agencies or agents in each particular country.

Jan 1, 1993

By John P. Albers

During the 1950's and 1960's a program of geologic mapping of counties has been underway in Nevada by geologists of the U. S. Geological Survey and the Nevada Bureau of Mines. The aping has been done principally at reconnaissance scales, with more detailed work in local areas. Geologic maps are either published or open-filed for about a dozen counties at scales of 1:200,000 or 1:250,000. One by-product of the geologic mapping has been the recognition of about 80 Tertiary volcanic centers from which large or very large volumes of volcanic material ranging from rhyolitic to andesitic in composition have been erupted. For purposes of this discussion these are regarded as the major centers; the tally does not include hundreds and perhaps thousands of small rhyolitic domes and plugs and basaltic vents. About 15 to 20 of the 80 major centers are believed to be calderas ranging in diameter from 3 to 25 miles. Some have been described in the literature by geologists of the Nevada Test Site and others. However, the vast majority of the 80 centers have not been described in print, and we are indebted to our colleagues for locating them for us in many of the counties. Briefly, we would like to express our appreciation to the following people all members of the USGS unless identified otherwise: Robert Coast, who has identified the centers in Elko County; Ron Willden, Robert Yates, and

Jan 1, 1968

By L. G. Austin, R. S. C. Rogers

INTRODUCTION Coal is geologically a sedimentary rock with distinct bedding planes containing a mixture of petrographic constituents. Yet. because of its chemical nature, it also has some of the characteristics of a polymeric material. In addition, it is extensively precracked to give a macropore structure and also has a substantial internal volume of microporosity. Add to this the mineral constituents dispersed in the coal in a variety of forms and sizes. and it can be readily appreciated that coal is a complex and heterogeneous material. It has to date not been possible to predict the particle size distributions produced by breakage of coals from a priori application of the principles of fracture mechanics. However, there is a substantial body of data resulting from empirical observation of size distributions produced under various conditions, primarily from grinding mills. It is the function of this review to outline how this empirical information can be used to predict product size distributions for those systems which have been studied systematically, and to suggest future avenues of research using similar methodology. FRACTURE THEORY APPLIED TO COAL It is, of course, possible to devise experiments for slow crack propagation in a coal. However, the evidence is that coal breaks by brittle fracture in the mills and mining machines of industrial importance and therefore the theory of brittle fracture is sufficient to illustrate the important features of the fracture of coal. In order to produce size reduction a solid must be stressed by the application of force. The force can be a tensile (stretching), compressive, or shear force, and the three dimensional stress pattern in the solid represents the tensile, compressive, and shear forces per unit area acting in any direction through any point in the solid. As an illustration consider the case of a simple one-dimensional tensile stress: then stress is defined as a=F/A where F is the force. A is the cross-sectional area of the solid normal to F and strain. E, is defined as the fractional change in the length of the solid. so that E= x/L where x is the extension of an original length of L. Coal behaves as an elastic material over short times (although viscoelastic creep can occur if the stress is maintained over long times) and if it is not stretched too far the coal returns to its original shape when the stress is removed; otherwise catastrophic failure occurs and the coal fractures at a stress termed the tensile strength. The failure under stress of an elastic material is termed brittle fracture. Elastic material fails at small stain and the stress-stain relation to where brittle fracture occurs is the empirical Hooke's law. a= YE, where Y is Young's modulus. The work done on the solid to take the solid from zero external stress to a stressed state by slowly increasing F up to a final stress u is the integral of the stress times the strain. This reversible strain energy is stored in the solid and. using Hooke's law. is u /2Y per unit volume of solid. If the solid is immediately loaded to u the work done is [EAuL] which Is a2 /Y per unit volume, that is, twice the reversible work.

Jan 1, 1988