Search Documents

By R. T. Hukki

The paper describes a two-stage industrial hydraulic classification system including hydrocyclones for primary classification and newly developed cone classifiers for secondary classification. Performance data based on large scale grinding and classification tests are presented.

Jan 1, 1981

By Milos Krofta, Donald B. Aulenbach, James P. Van Dyke

INTRODUCTION An innovative Ø.1-MGD (378.5-m3/day) biological and phyicochemical wastewater treatment system at Hancock, Massachusetts, USA, has been treating the domestic sewage generated from the four-season Jiminy Peak timeshare resort since 1985. The influent raw sewage is collected and equalized in an equalization tank, then biologically treated by two rotating biological contactors (RBC). A portion of the RBC effluent is discharged to a secondary sedimentation tank to simulate conventional waste treatment by a conventional RBC system. For parallel treatment the remaining portion of the RBC effluent is discharged to an innovative Sandfloat (SASF-8) clarifier to simulate a two-stage biological and physicochemical treatment by RBC-Sandfloat. Both secondary sedimentation effluent and Saandfloat effluent are later combined together and discharged to a tertiary sand filter and two UV disinfection'units for final polishing. The operation and performance data of Jiminy Peak plant in the period of May 1985 to March 1988 was fully documented in the Lenox Institute technical report No. LIR/Ø3-88/292 (391 pages, March 1988). This report presents only background information and complete plant data in the period of April 1988 to January 1989. Dr. Lawrence K. Wang and Mr. James P. Van Dyke have been the Consulting Engineer and Director of Special Projects, respectively, for the Jiminy Peak Project since 1985. (Key Words) Innovative and Alternative Technology, Rotating Biological Contactor, Sandfloat, Dissolved Air Flotation, Sedimentation, Tertiary Filtration, Ultraviolet, Disinfection. BACKGROUND INFORMATION Jimmy Peak, Inc., Hancock, Massachusetts, has designed and constructed a secondary wastewater treatment system consisting of preliminary/primary treatment facilities, two rotating biological contactors, a dissolved air flotation clarifier, a secondary sedimentation clarifier, a sand filter and two ultraviolet (UV) disinfection units. Total average wastewater flow is approximately Ø.1 ) (378.5 cubic meters per day). In accordance with the Consulting Engineer's preliminary design, the total wastewater stream is initially collected and equalized by an equalization tank, and then biologically treated by rotating biological contactors (RBC). Part of the RBC effluent is diverted to a Krofta Sandfloat (SASF-8) for physicochemical clarification in order to simulate an innovative RBC-Sandfloat two-stage waste treatment system. The remaining part of the RBC effluent is diverted to a sedimentation tank for secondary clarification in order to siumulate a conventional secondary RBC-sedimentation waste treatment system for the purpose of parallel comparison. Both Sandfloat effluent and sedimentation effluent are later combined together and discharged to the subsequent sand filter and UV disinfection unit for final polishing. Figure 1 shows the flow diagram of Jiminy Peak Plant. The Massachusetts Clean Waters Act (M.G.L.c.2l,s.26-53) was amended by Chapter 246 of the Acts of 1973 to authorize the Massachusetts Department of Environmental Quality Engineering (DEQE), Division of water Pollution Control, Boston, Massachusetts, to regulate discharges into all waters of the Commonwealth of Massachusetts, including groundwaters. The DEQE regulates discharges through the issuance of discharge permits which impose limitations on the amount of pollutants which may be discharged in the effluent, together with monitoring and reporting requirements and other conditions to insure adequate treatment of all liquid wastes prior to discharge. The DEQE reviewed the application submitted on behalf of Jiminy Peak, Inc. for a permit to discharge sanitary wastes from the Jiminy Peak secondary wastewater treatment system located off Brodie Mountain Road, Hancock, Massachusetts, and subsequently developed the conditions contained in the Groundwater Discharge Permit No. Ø-188. More specifically, Jiminy Peak, Inc. (i.e. the permittee) has been authorized to discharge into the ground from the Jimmy Peak secondary wastewater treatment facilities for which the Permit No. Ø-188 was issued, a treated effluent

Jan 1, 1989

By D. R. Nagaraj

Editor&apos;s note: Minerals concentration is a disparate area, one involving many disciplines. Flotation, flocculation, reagents, microbial processes, gravity and magnetic separation, and the areas of coal and oil shale - concentration is relevant to all of these. In his article, Nagaraj reviews the latest developments and findings in concentration that have ocurred during the past year. Flotation The Monograph Series "Development in Mineral Processing," (Elsevier, 1985) was devoted to "Flotation of Sulfide Minerals." This volume has 26 articles covering the aspects of flotation chemistry, process development, plant design and equipment, and modeling and process control. The numerous articles on sulfide flotation had one recurring theme - the role of electrochemical processes and redox potentials in flotation and depression. Significant advances have been made in this area. A differential desorption-reflotation process was developed for the beneficiation of calcitic phosphate pebble (Hsieh and Lehr, Industrial Engineering and Chemistry, 1985). The carbonate and phosphate minerals were first separated from silica using fatty acid and the modifiers diphosphonic acid and HF. The collector on phosphate was then desorbed using sulfuric acid, and calcite was selectively floated without additional collector. A two-stage conditioning - initially at pH 10, followed by that at pH < 4.5 - with sodium oleate was developed to improve the separation between apatite and dolomite (Moudgil and Chanchani, Minerals and Metallurgical Processing, MMP, 1985). Separation of Mussorie rock phosphate in India from gangue calcite, dolomite, silicates, pyrite, and carbonaceous impurities was achieved with a three-stage flotation only on -75 µm (-200 mesh) fraction (Vaman Rao et al., International Journal of Mineral Processing, IJMP, 1985). The separation of fine SiC whiskers from other products of coked rice hulls by immiscible liquid and froth flotation was achieved using M1BC, pine oil, and mineral spirits (Parekh and Goldberger, MMP, 1985). Flotation was more economical. The carrier flotation separation of hematite fines from quartz fines was effected using coarse hematite as a carrier and oleic acid and ferric chloride (Cristoveanu and Meech, CIM Bulletin, 1985). Potash recovery from brines by laboratory-pan solar evaporation and amine flotation was discussed by Foot and Juiatt (Salts and Brines &apos;85, Proceedings, 1985). Flotation in a 45-kg/h (99-lb per hour) unit recovered more than 95% of the potash in schoenite and sylvite concentrates containing 28% and 62% K2O, respectively. The effects of fresh concrete into cement and aggregate by a single-step flotation process in aqueous suspension was described (Naegle, Chemical Engineering Science, 1985). The physico-chemical principles for the selective separation of proteins from mixtures using flotation were discussed by Ostermaier and Dobias (Colloids & Surfactants, 1985). Selective flocculation of hematite from silica was studied by Bagster and Mcllvenny (IJMP, 1985). Selective flocculation was more favorable with more highly charged anionic polyacrylamides and with high molecular weight. The cationic and non-ionic polymers flocculated both minerals. In minerals mixtures, there appeared to be very little selectivity unless a combination of dispersant and electrolyte was used. The effect of dissolved minerals species, such as Cu, Fe, and Ni on flocculation of chalcopyrite, pentlandite, millerite, pyrrhotite, and covellite was studied by Acar and Somasundaran (SME-AIME, 1985). Reagents There were some major advances made in reagent development for the minerals processing industry. Cyanamid introduced several classes of collectors, one of which - the diaryl monothiophosphates as acid circuit col¬lectors of sulfides and oxidesulfide ores - was commercialized in 1985. The monothiophosphates are more stable and powerful collectors than the xanthates and dithiophosphates. Hydrolyzed dithiophosphate containing 80% monothio and 20% dithiophosphate was found to give optimum recovery of copper from crude cementation precipitate and separation of Cu and Ni sulfides from matte (Akimova et al., Obogashch, Tonkov, Rud, OTR, 1985). A new class of O-alkyl-Nallyl

Jan 9, 1986

By Thomas B. Faddies

The Trixie mine is located in the East Mining District. Since production began in 1970 over 450 000 tonnes of ore grading 239 grams of silver, 6.9 grams of gold, and 1.2% Cu have been mined from veins in Cambrian Tintic Quartzite. Detailed geologic mapping and extensive sampling are essential for compiling the data base required for efficiently developing and mining known reserves as well as planning exploration and development work. Although the basic techniques used by the geology group at the Trixie were developed many years ago, the reduced activity in underground precious metal mining in the U.S. have made these techniques less familiar to many presently active geologists. The increased activity in precious metals search and exploration again offer cause for the application of these techniques as a prerequisite to efficient exploration, development and production.

Jan 1, 1983

By John D. Nelson

Unprotected uranium mill tailings impoundments can pose a significant risk to nearby inhabitants and the surrounding environment in the event of a prolonged or catastrophic release of contaminants contained in the tailings. As a result of this potential, reclamation plans for such facilities must include engineering designs to protect against disruption of the tailings and the potential release of radioactive materials. The goals for such engineering designs should be to provide overall site stability for long-term periods with no need for planned ongoing maintenance and to provide a repository for the tailings that will not place a burden on future generations. Although the goal is to provide a maintenance-free system that does not require monitoring, it must be recognized that some period of surveillance would be reasonable. The surveillance period could be relatively short and only needs to assure with reasonable confidence that the reclamation scheme that was implemented is functioning adequately. An investigation was conducted by Nelson, Volpe, Wardwell, Schumm and Staub (1983) entitled Design Considerations for Long-Term Stabilization of Uranium Mill Tailings Impoundments (NUREG/CR-3397). This report assesses the degree of confidence with which long-term reclamation plans can be expected to remain effective over specific periods of time, and to assess the additional effort required to extend the design period from one long-term period to a longer one. This paper presents a summary of that investigation and discusses some of the important conclusions.

Jan 1, 1984

By Milton H. Ward

The percentage of exploration dollars flowing out of the industrialized countries continues at an all-time high, and this shift in risk money is justified (Samuels, 1990; Bosson, 1977). Clearly, the odds of discovery are greatly enhanced if exploration is pursued in an untrampled and geologically more prospective environment. Unfortunately, such major unexplored areas of the developed world are shrinking rapidly, not just because the lands have already been tested, but primarily because they have been withdrawn from exploration. Experience, however, has shown that foreign investment is not without risks. These include problems that result from working in isolated areas, a lack of infrastructure, untrained workers and an absence of a solid geological data base. While the likelihood of once-feared expropriation is now low, mining enterprises still must take precautions to gain the support of their constituencies, including a variety of governments (local, provincial and central), workers, environmentalists, cultural organizations and local landowners. Is foreign exploration worth the risk? In most cases, Yes! But maintaining tenure and long-term success in a less developed country is only likely with good planning and the use of appropriate safeguards. These include measures such as buying country-risk insurance, building multinational relationships, forming joint investments, developing a broad customer base and seeking local investors in the company (Cobbe, 1979). The primary theme of this lecture is: How a company handles its constituency is critical to long-term tenure in a foreign country. Ideally, a multinational mining company would be so effective in dealing with the local people and managing its relationship with the host government that it would become a preferred employer, preferred over its competitors and over local companies. Historical overview Our earliest ancestors lived in Africa three to four million years ago. The Paleolithic or Old Stone Age, about 500,000 years ago, marked the beginning of mining in its earliest form (Gregory, 1980; Wolf, 1984). Various types of rocks and stones were used for tools and weapons, with flint being the preferred resource for implements. Initially, these materials were collected as stones (eoliths) lying on the surface. Then they came from excavations of flint in limestone beds that were exposed in river banks or naturally occurring excavations. Later, more formal mining developed. No doubt tribes of the Old Stone Age experienced conflict over rights to eoliths, food and land. The question of who owns the land and has rights to its contents and what is fair value for extraction is still the subject of intense debate and, occasionally, open conflict. As time passed, the search for useful minerals required migration from one area to another. Later, voyages from Europe to the New World and travels to other remote regions were funded and supported by absentee investors, kings and such (Rogers, 1976). The primary objective of such funding was to obtain gold, silver, food stuffs and other commodities that could be collected from the new countries. This is still the objective of foreign investment.

Jan 1, 1994

By C. H. Bucknam

Metallurgical processing of gold ores in positive water balance environments has been facing decreasing discharge concentrations in permits and additional requirements to pass acute toxicity testing before discharges will be allowed to native fisheries. In response to the challenge to meet 0.005 mg/L free cyanide guidance for discharges to fresh water fisheries, the American Society of Testing and Materials (ASTM) International Cyanide Task Group has undertaken an interlaboratory study for the free cyanide method in the metallurgical processing cyanide detoxified reverse osmosis effluent to determine if the quantitation limit for the method could be lowered from the current 0.009 mg/L free cyanide (1) to less than the 0.005 mg/L guidance concentration. Results of the testing are presented below.

Jan 1, 2012

By J. M. Rios

This paper exposes the reasons that led the Empresa Nacional Minera del Sahara, S.A. (ENMINSA) to the selection of a conveyor belt system for the transport of phosphate rock over a distance of 100 kilometers. ENMINSA was created in 1962, with the main objetive of the exploitation of phosphate rock deposits in the Spanish province of Sahara, in North West Africa. Poor grade outcrops were known previously. A detailed geological research carried over the province led ENMINSA to the discovery of deposits not exposed, and of much higher grade. The sector known as Bu-Craa was chosen as the most promising, and was explored by means of drill holing and shafting. The important amount of information obtained permitted a detailed evaluation of the capacity and grade of the rich ore contained in the Bu-Craa area. Simultaneously with the systematic reconnaissance of the Bu-Craa deposits, ENMINSA developped the study of the technical and economical problems required for the beneficiation of the rock, which comprised five main groups of projects: rock exploitation; beneficiation plant; rock transport from the mine site to the Atlantic coast; storage, handling and loading facilities by the sea- side, and power plant. Once determined the location of the marine loading facilities, which to date are in an advanced stage of construction (figs. 1 and 2), the studies conductive to the selection of the best transport system from the mine to the ocean, along 100 kms. distance were undertaken.

Jan 1, 1968

By K. C. Liddell

Chemical processing research made notable advances during 1986. This overview is necessarily brief. It is intended, though, to give the flavor of selected areas where recent activity has been high. At the 1986 Annual Meeting of The Metallurgical Society, a symposium was held on hydrometallurgical reactor design and kinetics. R. G. Bautista, R. J. Wesely, and G. W. Warren edited the resultant proceedings volume. This is the first available volume on this subject. It includes 26 papers on fundamental kinetic studies, modeling of reaction kinetics and reactor performance, and pilot and production-scale operations. Metals discussed include silver, gold, platinum, titanium, cobalt, nickel, zinc, copper, manganese, and iron. Agitated tanks, heaps, dumps, pachucas, pressure auto-claves, electrolytic reactors, liquid membranes, and fluidized beds are among the reactor types covered. An international symposium dealt with iron control in hydrometallurgy. It was sponsored by the Metallurgical Society of CIM, the Institution of Mining and Metallurgy, The Metallurgical Society of AIME, and Gesellschaft Deutscher Metallhutten and Bergleute. J. E. Dutrizac and A. J. Monhemius edited a proceedings volume containing 41 papers. These covered many areas of process chemistry, solvent extraction, precipitation, treatment of pickle liquors, impurities, residues and the environment, and process selection. Precious metals Concerning precious metals processing, the US Bureau of Mines IC 9059 is noteworthy. It includes papers presented at a USBM briefing at the Western Mining Conference in Denver. Topics covered included ion exchange, staged heap-leaching direct-electrowinning, and mercury precipitation during cyanide leaching of gold ores. Also dealt with were carbonaceous gold ores, carbon adsorption and desorption, heap leaching, the carbon-in-pulp process, and precious metals recovery from electronic scrap and solder. R. C. Sandberg and J. L. Huiatt (Journal of Metals, June 1986, and USBM RI 9022) developed a method to recover silver, gold, and lead from a complex sulfide using ferric chloride, thiourea, and brine-leach solutions. Gallium Gallium recovery was also a subject of considerable interest. Much information on this topic is proprietary. But two papers described solvent extraction of gallium. V. P. Judin and R. G. Bautista (Metallurgical Transactions B, 1986) developed an equilibrium model to separate gallium chloride from aluminum chloride. Tributyl phosphate was the extractant studied. T. Sato and H. Oishi (Hydrometallurgy, 16, 1986) investigated gallium extraction from sodium hydroxide by using Kelex 100. Data were given on the equilibrium distribution and the extraction kinetics. Galena Interest continues in recovering lead by hydrometallurgical processing of galena. J. E. Dutrizac; S. H. Kim, H. Henein, and G. W. Warren; and M. C. Fuerstenau et al. (Metallurgical Transactions B, 1986) all investigated leaching of PbS by ferric chloride. Dutrizac reported parabolic kinetics and reaction control by outward diffusion of lead through a porous layer of elemental sulfur. Kim, Henein, and Warren, however, reported that two leaching reactions occur. A nonoxidative reaction produces H2S and there is an oxidative leaching by ferric ion. Acid dissolution was found to predominate when the acid activity to ferric activity ratio is high. Surface chemical reaction was reported to be controlling. Fuerstenau et al. also reported that mass transfer through the sulfur layer is rate determining. But they believe that the species transferred are chloro complexes of ferric ion. In other work on lead, A. Y. Lee, A. M. Wethington, and E. R. Cole, Jr. of the USBM described an environmentally acceptable hydrometallurgical alternative to the smelting of lead concentrates (RI 9055). Uranium In spite of depressed prices, much work has been reported on uranium processing. R. G. L. McCready, D. Wadden, and A. March-bank (Hydrometallurgy 17, 1986) described the nutrient needs for in-place leaching by T. ferrooxidans. They reported the optimal conditions for uranium solubilization. L. E. Eary, H. L. Barnes, and L. M. Cathles (Metallurgical Transactions B, 1986) carried out an experimental and modeling study of uraninite dissolution. They concluded that ferric ion preferentially leaches uraninite in pyritic ores. Hydrogen peroxide was found to be less selective. A. Vuorinen, P. Hiltunen, and O. H. Tuovinen (Hydrometallurgy 15, 1986) studied redox and precipitation reactions of iron and uranium in leach liquors. P. T. Chiang (Hydrometallurgy 17, 1986) reported on the effect of uranium loading in the DEPA-TOPO process to separate uranium and iron from wet-process phosphoric acid. F. J. Hurst (Hydrometallurgy 16, 1986) conducted a fundamental study of the separation of uranium from phosphoric acid by DEPA and TOPO. D. E. Chia and W. C. Cooper (Hydrometallurgy 16, 1986) reported on bench and pilot scale work to recover uranium by the HIMIX process. They reported that the acid consumption to produce an eluate suitable for yellowcake

Jan 5, 1987

By W. A. McKinney

The U.S. Bureau of Mines, Kennecott Copper Corp., and New Mexico Institute of Mining and Technology are cooperating on a research project to improve extraction of copper from previously leached waste dumps that are in part compacted and impervious to leach solutions. The field work is being done at the "J" leach dump, Chino Mines Division, Kennecott Copper Corp., Santa Rita, N. Mex. The laboratory percolation leaching tests were made at the U.S. Bureau of Mines Salt Lake City Metallurgy Research Center on drill core samples from the "J" dump to determine how much copper might be leached if permeability could be restored by explosive heaving or other means. The core samples from nine drill holes on "J" dump contained from 0.06 to 0.14 percent copper. Copper extractions ranging from 15 to 3 percent were obtained in 75 days by percolation leaching of minus-1-inch material with dilute sulfuric acid. The tests results indicate that about 2&apos;7 percent of the copper remaining in the "J" dump could be extracted under ideal leaching conditions.

Jan 1, 1970

By Egon Pohl, Peter Eckl, Friedrich Steinhäusler, Johanna Pohl-Rüling

RADON EXPOSURE AND CARCINOGENIC CELL TRANSFORMATION The highest radiation burden to miners is due to inhalation of radon and its short-lived decay products. The quantification of the risk associated with this radiation burden is complicated by modeldependent lung dosimetry, insufficient accuracy of past human exposure data as well as lacking knowledge about potential synergism of various carcinogens. Nevertheless, it is evident from epidemiological studies of miners that inhalation of elevated levels of radon daughters is correlated with increased lung cancer incidence (UNSCEAR, 1977). The situation is further complicated by the lack of reliable data on the biological variability of the latency period for the development of lung tumor under varying exposure conditions. At present information on variation with age is scarce, however, it is indicated that the excess lung cancer rate for workers exposed to high radon levels is considerably higher, if exposure occurs at ages over 40 years as compared to under 30 years of age (Sevc, Kunz, Placek, 1976). Furthermore, latency period is shorter by 6 - 7 years for smokers exposed to elevated radon levels than for non-smokers (Fry, 1976). Analysis of US- and CSR-uranium miner data revealed that the mean latency period is in the order of about 15 years (Jacobi, 1973). These uncertainties, together with medical diagnostic shortcomings, lead to the dissatisfying situation that at present the detection of radon induced injury of mining personal is primarily the assessment of the endpoint, i.e. radiation induced cancerous transformation of lung cells with typically less than 10% chance for recovery. Therefore it would be advantageous to develop practically applicable diagnostic aids to indicate already early precancerogenic changes of cell characteristics. This would permit the identification of specific population groups at increased risk for the development of lung cancer, thereby increasing the chances of more successful medical treatment. Despite continuous improvements in the reliability of test methods for the diagnosis of cancer cells there is still need for techniques, which enable the detection of transformed cells before the onset of invasion of the host organism. It is generally recognized that the transformation of a cell into a malignant state leads to a change of the cell surface, indicating a correlation between membrane-specific immunological properties and loss of growth control. Surface alterations on cells appear to be responsible in part for the malignant state and are not simply secondary effects of the transformation (Schnebli and Burger, 1973). Furthermore, membranes of cancer cells differ significantly from those of normal cells, particularly, in permeability properties (Rastogi, 1976). In dying cells, proteins, glycoproteins, peptides, aminoacids and their breakdown products are released, which block the permeation of the membrane itself. A mammalian cell can be considered as a 3-phase system (interior, boundary, environment) with the membrane forming a heterogeneous barrier between two subsystems. Under normal circumstances a difference of chemical potential is maintained on both sides of the membrane, causing an ion gradient across and fixed surface charges on the membrane. This results in a membrane resting potential (MRP) between cytoplasm and the bulk medium. It has been shown that MRP is a highly sensitive indicator for cellular reactions due to physical, chemical and biological agents, particularly whenever phenomena of transport and ion gradients as well as permeability are involved (Redmann, 1980). The primary interaction of the agent "ionizing radiation" with any form of living matter occurs at the cellular level. The component with the highest hit probability is the cell membrane. In the study presented MRP-changes of human cells were investigated with simultaneous measurements during irradiation and post-irradiation intervals up to six days. Furthermore, the suitability of MRP-measurements of human cells was tested as an indicator for early changes of cellular properties prior to the histological confirmation of carcinogenic transformation. EXPERIMENTAL METHODS Lung cells The biological specimen used were cultured human lung cells and human lung biopsy samples. Monolayers of lung fibroblasts (W138) were grown in petridishes using conventional culture techniques. In addition, transformed lung cells (W138SV13, subline 2RA) were used applying similar culture methods. All petridishes were incubated at 37°C and only cells in logarithmic growth phase were used. Freshly excised lung biopsy samples were obtained from randomly selected male and female patients (20 cases), where suspected or unclear malignancies were indicated by clinical or X-ray observations. At the time of sampling 80 % of the patients were or had been smokers in the past. The samples were taken by means of a stiff bronchoscope introduced into the trachea under local anasthesia with 1 % Novesinsolution (preparation with Atropin and Pantopen). This permitted the observation of both main bronchi down to the segmental bronchials. From each patient two tissue samples were excised from the mucusepithelial layer under visual control with fiber optics and transferred immediately into 1 % NaClsolution. One sample was taken from the suspected

Jan 1, 1981

Though the mining industry is beset with problems-a broad slump in metal prices, a rash of acquisitions and takeover attempts, rising capital costs, and an aggressive Canadian energy program-there was an under-current of optimism at the 1981 AMC conference that&apos;s been missing at industry meetings in recent years. The industry anticipates a turnaround in the 1980s, buoyed perhaps by the new spirit of cooperation from the Reagan administration. For the first time in years, it appears that Washington and the mining industry share mutual goals for developing the nation&apos;s resources. A number of prominent Reagan officials were on hand during the three-day conference in Denver, September 28-30, to reassure conferees that restrictions plaguing energy and minerals development would be eased. Interior Secretary James Watt and other government speakers promised cooperation in bringing balance to federal public lands policies, a review of regulations that have hampered the industry, and prompt action on domestic minerals policy. Daniel N. Miller, Jr., assistant interior secretary for energy and minerals, said, "It is our intent to dismantle the overhearing bureaucracy that has stifled mineral and energy exploration. We know that Interior&apos;s rules have shackled the mining industry in recent years, and we know that those rules must be eased." Miller noted that the administration will not permit mining on national park lands or wildlife refuges, but added that "we must assess a variety of uses of public lands ... we will restore lands to multiple use where practical." EPA administrator Anne Gorsuch assured industry representatives that the administration intends to work within environmental laws and with Congress to review and revise water, soil, and air pollution policies. "We have a strong commitment to see that there are major mid-course corrections" of air regulations, Gorsuch said. Support from these "new friends in Washington" will be crucial in light of the serious problems pressuring the industry. Copper prices have plunged to almost three-year lows and prices for molybdenum, gold, and silver have slumped. Earnings are down and today&apos;s high interest rates prevent a quick turnaround. Companies are on edge after the recent takeovers of Kennecott, St. Joe Minerals, and Texasgulf Though the companies may benefit from the major injection of capital that large energy firms can provide, many observers fear the new parent companies won&apos;t be willing or able to survive the cyclical metal markets. Arco and Gulf Resources, for example, have been criticized for closing Anaconda&apos;s Montana copper facility and the Bunker Hill unit in Idaho, respectively. Canada&apos;s national energy program has brought additional pressure on the industry. This policy, which emphasizes Canadian majority ownership of the country&apos;s energy sources, resulted in acquisition of Texasgulf&apos;s Kidd Creek lead-zinc-silver complex by Canadian and French interests. In response, the American Mining Congress adopted two resolutions on takeovers. One calls for the US government to review laws regulating tender offers and takeovers "to better ensure that principles of fairness and sound investment policy govern such transactions.&apos;&apos; The other asks the government to demand "fairness and reciprocity" as a basis for US policy governing international trade in minerals and investment relations with other countries. AMC&apos;s shopping list included four other priority goals, aimed primarily at the Interior Department: • Prompt implementation of Interior&apos;s efforts to bring order and balance to rules governing access to public lands for exploration and development. • Statement by the President of a comprehensive and coherent domestic minerals policy. • Amendment of the Clean Air Act to remove impediments to productivity and barriers to economic development that are not necessary to essential goals of the act. • Development of new approaches to better achieve worker health and safety in the most cost-effective manner without penalizing productivity. Almost 6000 mining industry executives attended the 1981 convention-the largest in AMC&apos;s 84-year history. As in years past, the conference offered a wide spectrum of presentations-nearly 100 papers in 26 sessions-ranging from commodity forecasts to the latest technical achievements. New Administration Stockpile Goals The minerals availability session included a presentation on management of the minerals stockpile by Paul K. Kruege r of the Federal Emergency Management Agency. Krueger notes that rather than providing incentives for development of a domestic raw materials industry, the government has "a history of providing disincentives to industry." In mining industries, he adds, the rate of productivity growth has been -6% over the last six or seven years. Krueger feels there will be a major change under the Reagan administration. In March 1981, FEMA began the first purchase program for the national defense stockpile in over 20 years. The stockpile is sadly out of balance, Krueger adds. Stockpile materials are

Jan 12, 1981

By M. E. Breitrick

Newmont Gold Company began full production in early 1995 at the Carlin East underground mine. The mine is currently producing at the rate of 900 tpd (1.000 stpd). for an annual production of 150.000 ounces. Approximately one hundred twenty five hourly and salary personnel are employed at the project for the estimated six-year mine life. Two mining methods are currently utilized at the mine. Longhole stoping with cemented backfill accounts for 70% of the total mine production. Conventional underhand drift and cemented fill accounts for the balance of the daily tonnage. In December 1996. Newmont purchased a new AC-Eickhoff ET-210 Roadheader. The machine went into service in mid-June of 1997 and is used in both longhole stope topcut development and cut and fill production at a rate of 225 tpd (250 stpd). The Carlin East mine is operated by Newmont Gold Company. The mine is one of four underground gold mines in production in northeastern Nevada owned by Newmont Gold.

Jan 1, 1998

By James R. Hindman

Vermiculite is the mineralogical name generally applied to a group of hydrated, trioctahedral ferromagnesian aluminum platty or micaceous silicate minerals. In microscopic particles the mineral as mineral is differentiated from montmorillonite by a higher Si:AI ratio of approximately 3:l and a higher layer charge and higher cation exchange capacities. Commercial vermiculite, the vermiculite which is mined, beneficiated, and discussed in this chapter, is an important industrial mineral which is formed by the alteration of macroscopic particles of biotite and iron-bearing phlogopite. In natural form it has the size and shape of mica, while possessing the ion exchangeable properties of zeolites and some clays. Within the internal structure of vermiculite lie water molecules, which when rapidly heated to high temperature, transform into steam causing the vermiculite particles to increase in volume. This process of thermal exfoliation produces a lightweight product which finds use in various construction products, agriculture, horticulture, and other industrial applications. In exfoliated form it has the low density and biological inertness of expanded perlite, while maintaining a chemically active surface. Most of the uses of vermiculite are for the thermally exfoliated material. In addition, the cation exchange potential of vermiculite and its layer-silicate structure are properties which can be used as the basis for numerous products including intumescent coatings and gaskets, inorganic films, and the treatment of nuclear and other toxic waste. When chemically and physically modified, it possesses some properties common to organoclays and synthetic compounds. In high purity concentrates and manufactured products, these properties can be altered and optimized in applications to produce superior performance. GEOLOGY Mineralogy Vermiculite was first described as a mineral by Thomas H. Webb in 1824. Webb believed vermiculite to be a variety of talc and described its diagnostic property of thermal exfoliation thusly: "If subjected to the flame of a blowpipe, or that of a common lamp, it expands and shoots out into a variety of fanciful forms, resembling most generally small worms having the vermicular motion exact." Observing that with one exception, all commercial vermiculite has formed by the alteration of iron-bearing phlogopite, a simple definition of vermiculite might be the alteration product of trioctahedral micas, macroscopic particles of which display marked exfoliation when heated rapidly to temperatures above 374°C (the critical temperature of water). The first vermiculite described was found near Worcester, MA, but it was later pointed out by Brush (1866) that vermiculite had been known for some time in Japan as a children&apos;s novelty. Because the techniques for mineral analysis were somewhat primitive com- pared to those routinely available today, and because the structure and crystal chemistry of the micas and related minerals were not widely understood, the early literature generated at least 20 "new" minerals which were nothing more than variations in the color and chemistry displayed by vermiculite. Trade names such as Dugarlite, Mandolitem, Strong-LiteTM, and Zonolitem are sometimes used to denote commercial vermiculite, thermally exfoliated vermiculite and their products. Vermiculite particles resemble mica and vary in color from colorless through tan and green to black, depending on the chemical composition. Most physical and optical properties are close to those of biotite, with perfect basal cleavage, hardness between 1.5 and 2.5 Mohs, and specific gravity between 2.2 to 2.8. Fine-sized particles will feel talcose, especially when wet. However, for commercial vermiculite the diagnostic test is that of thermal exfoliation. Vermiculite can display a wide range of compositions, depending on the composition of the original mica and the change of chemistry during weathering and ion exchange. Chemical data for some commercial vermiculites are given in [Table 1]. There are numerous analyses for vermiculite given in the literature, and the analyses of vermiculites from commercial deposits will fall within the range indicated by the average analysis in the table. Many analyses separate the adsorbed water (H2OP) from crystalline water and water as hydroxyl (H20+). The basis of separation of adsorbed water is generally considered to be 100°C. However, hydrate water within the vermiculite interlayer begins to be lost at 75°C and lower. Therefore, measured water content and loss on ignition are combined in the table as H20[total].

Jan 1, 1994

By James L. Hendrix

This paper is intended to give the reader an update on the work being done at the Mackay School of Mines about the fate of cyanide on precious metals mill tailings waste. During the last two years several tailings impoundments have been sampled and analyzed for total and free cyanides. From our sampling program we are beginning to learn valuable information concerning the fate of cyanides in precious metals mill wastes. Included in this paper is a detailed description of our sampling and analytical techniques. Also, some of the data obtained from five sites are given.

Jan 1, 1986

By A. de Ferran

Is the Brazilian gold rush over? Judging from the situation in Brazil over the past few decades, the answer is almost certainly yes. The picture of swarms of Brazilian prospectors or "Garimpeiros" crowding or, more correctly, overcrowding the gold regions of the Amazon jungle using the time-aged empirical approach to gold exploration has finally run its course. There are two fallacies that have lead to a reduction in the discovery of new gold fields in Brazil. The first fallacy is that "Brazil&apos;s geology is largely unknown." The extreme depth of weathering and the general lack of understanding of the shield deposits are at the origin of this misconception. The second fallacy is that "Brazilian prospectors (`garimpeiros&apos;) are very naive, have very little technical knowledge and can only produce gold at very low recovery rates." This is more of a result of wishful thinking for the purpose of justifying limiting exploration programs than it is a real consideration. In this paper, the author takes a methodical heuristic approach to gold exploration in Brazil and offers this as an alternative to the empirical approach of the garimpeiros.

Jan 1, 1997

By A. de Ferran

Is the Brazilian gold rush over? Judging from the situation in Brazil over the past few decades, the answer is almost certainly yes. The picture of swarms of Brazilian prospectors or "Garimpeiros" crowding or, more correctly, overcrowding the gold regions of the Amazon jungle using the time-aged empirical approach to gold exploration has finally run its course. There are two fallacies that have lead to a reduction in the discovery of new gold fields in Brazil. The first fallacy is that "Brazil&apos;s geology is largely unknown." The extreme depth of weathering and the general lack of understanding of the shield deposits are at the origin of this misconception. The second fallacy is that "Brazilian prospectors ("garimpeiros") are very naive, have very little technical knowledge and can only produce gold at very low recovery rates." This is more of a result of wishful thinking for the purpose of justifying limiting exploration programs than it is a real consideration. In this paper, the author takes a methodical heuristic approach to gold exploration in Brazil and offers this as an alternative to the empirical approach of the garimpeiros.

Jan 1, 1998

By A. E. Hall

INTRODUCTION Underground gold mining operations are found in South Africa, U.S.S.R., Canada, the United States, Zimbabwe, Ghana , Brazil. Australia, China and many other countries. The methods used for extraction differ from highly mechanized trackless mining in the developed countries to the labour intensive systems of the third world nations. The climatic conditions in which mines are situated vary from equatorial to arctic. The rock temperatures and the depth of workings also vary significantly from shallow to extreme depth. The Western Deep Levels mine in South Africa is the deepest and exceeds 4.000 metres in depth with strata temperatures above 55°C. These major differences between mining fields result in significantly different ventilation problems in underground gold mines. The ore types also vary and some deposits have high silica contents while other mines extract sulphide ores. Methane may also be encountered in underground gold mines and can have a large influence on the ventilation practice. Several topics are currently of concern to operating mines and are reviewed here:- a) Air circulation and fans b) Mine cooling c) Permafrost operations d) Mine heating e) Control of diesel exhaust f) Gases, fires and explosions

Jan 1, 1988

By I. K. Kapageridis

Digital photography combined with three dimensional models of topography, mining operations and restoration plans can lead to extremely realistic images and animations of the current and future states of a mine or quarry. The amount of work and the time required for the successful modeling of a mine and its restoration plan are surprisingly low nowadays. All this means that the visual impact of mining and quarrying operations can be easily assessed using common computer hardware and some dedicated software packages. LAVA Mining and Quarrying SA is a company committed to strive continuously for the highest possible environment protection at the company?s quarries. The pozzolanic rock quarry located at Xylokeratia is one of the company?s quarries on the island of Milos and the subject of the study presented in this paper. A thorough restoration plan of the Xylokeratia quarry is being completed by the company. For its purposes, a complete visual impact assessment study was performed at the Department of Geotechnology and Environmental Engineering of the Technological Education Institute of Western Macedonia. The procedures used in this study and the produced visual results are presented in this paper.

Jan 1, 2006

By F. B. Henderson III

Since the "end" of the Cold War, revolutionary new research and commercial remote sensing capabilities are being developed that will dramatically change the way we map the earth and address its environmental problems. The technology challenge is not the growth of new environmental remote sensing technologies themselves. It is, rather, how these new innovative observing systems can be accepted and used to the benefit of both the regulatory and the mining communities in the light of present concerns about unknown risks of discovery and liability. The basis for this paper is an unpublished technology primer prepared for the industry-government Workshop on Advanced Measurement and Site Characterization for Mining Impacts held at Colorado School of Mines, Golden, Colorado, July 14-17, 1997

Jan 1, 1999