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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'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 Gabino Preciado, Louis Sandbak

Corrosion has long been identified as a potential risk to the long-term ground support stability due to degradation of internal ground support elements such as rock bolts but also to surface support from mesh, straps, bolt plates, and ancillary support of utilities such as hangers. The emphasis is to understand the corrosion mechanisms on the primary ground support elements and any supplemental steel or arch sets. The water and chemical processes from oxidation(rust), stress corrosion cracking, and even the electrical charge created during these reactions contribute to the corrosion of the steel support elements. The main goals are to mitigate the effects of corrosion and to be able to predict those areas of high water or high sulphide for potential rehab maps. It is also essential to identify and classify the visible corrosion as part of damage mapping and provide bolt testing to those areas of suspected internal damage from corrosion. This is important to get an estimate of the support longevity or expected life before rehab to minimize the overall cost of the operation.

Feb 1, 2024

By William Gleason

While a fleet of 100 t (110 st) haul trucks were busy removing overburden from the open pit mine in the distance, a host of dignitaries, including congressmen and California state representatives, gathered for Molycorp?s official groundbreaking ceremony at the Mountain Pass Mine on April 20. The mine, recognized as arguably one of the richest rare earths deposits in the world, is at the center of Molycorps? strategic ?Mine to Magnets? plan. It aims to secure America?s future supply of rare-earth-dependent technologies by developing a strong domestic rare earth industry. Molycorp identifies rare-earth-dependent technologies as those that cannot be produced without rare earth materials. The list of these technologies is long and growing. It encompasses everything from personal electronics and batteries for hybrid cars to permanent magnet generator wind turbines and national defense applications.

Jan 1, 2011

By L. M. Sandoval, R. Kaunda, C. N. Vasquez, S. C. Falcon

Artisanal and small-scale mining (ASM) involves a wide range of practices, from highly informal and minimally mechanized mining operations with predominantly manual work to formal practices carried out by small but high-tech industrial mining operations [1]. ASM may be a traditional practice, with skills passed from one generation to another. It can be an important driver of local economic development, while simultaneously contributing to a complex array of positive and negative socioeconomic and environmental impacts. There are more than 100 million artisanal and small-scale miners in 80 countries worldwide, and they supply around 20% of the worldwide gold production [2]. According to the Peruvian Ministry of Energy and Mining (MINEM), in 2020, 32% of fatal accidents in formal (legal) Peruvian mining operations were caused by groundfall events [3].The lack of resources, knowledge of best practices in health and safety, and insufficient equipment used in ASM make the probability of suffering work accidents very high. Furthermore, groundfall is one of the main causes of accidents and injuries in underground mines around the world [4], and it is also a concerning problem in ASM, where the associated fatality rate is similarly high. Unfortunately, a proper record of accidents in ASM is not kept, so an estimate of the actual number of groundfall accidents cannot be accurately developed [5]. Currently miners rely on empirical and observational tools acquired through previous experience to assess groundfall risks. The risks for artisanal miners can tend to be significantly greater than risks for those from the mining industry. This is due to the lack of regulation of ASM, which tends to operate outside the legal framework and the regulations lack of enforcement in force for occupational health and safety regulations.

Mar 2, 2022

By S. L. Bessinger

In the design and specification of a ventilation system for an underground mine, it is necessary to make reasonably accurate estimates of the pressure losses in the various airways of the mine. These estimates can be made with little difficulty for open airways with simple geometric cross-sections, such as those cut by continuous miners or tunnel-boring machines. The situation is much different on a longwall face, where the airway's complex geometric cross-section and the presence in the airway of obstructing equipment having a variety of shapes make it difficult, if not impossible, to estimate pressure loss using traditional methods of calculation. Headlosses in mine entries are calculated using Atkinson's Equation (1). [H = (English) H = (SI) (1)] where H = pressure ,loss, in. of H20 (Pa) K = friction factor, lbf min2/ft"4(Kg/m3) P = perimeter, ft. (m) L = airway length, ft (m) Q = airflow quantity, ft3/min (m3/sec) A = flow cross sectional area, ft2 (m2)

Jan 1, 1987

By D. Blackwell, W. R. Reed, G. Ross, S. Peters, M. Shahan

Dust collectors for roof bolting machines generally use a dry box to collect the roof bolting material. Recently, an underground mining operation converted a dry box dust collector to a wet box dust collector with a unique exception from MSHA for testing purposes. Water is routed to the roof bolter from the main water line of the continuous miner. The wet box utilizes a water spray to wet the incoming material. Testing was conducted comparing the two different collector types. Respirable dust concentrations surrounding the roof bolter with the different collection boxes were similar. The main difference in respirable dust concentrations occurred when cleaning the dust boxes. The average respirable dust concentration during cleaning of the wet box was 0.475 mg/m3, and during the cleaning of the dry box the average respirable dust concentration was 1.188 mg/m3. The silica content of the roof material was high, ranging from 28.9% to 52.7% during this study. The results from this study indicate that using the wet box as a collector reduced exposure to respirable dust up to 60%when cleaning the collector boxes. INTRODUCTION Currently, the dry vacuum dust collection system is the standard dust collector on roof bolters in underground coal mining. It has been proven to be an effective dust control to prevent roof bolter operators’ overexposure to coal mine respirable silica dust during roof bolting operations [Potts eta l, 2011 and Colinet, 2013]. The dry collection system works as follows: drill cuttings are vacuumed into the precleaner. The precleaner dumps oversized material onto the mine floor while undersized material enters the dust box via vacuum airflow produced by a blower. The cuttings entering the dust box are either deposited on the floor of the dust box or into a dust collector bag. The vacuum airflow leaves the dust box through a final filter which removes any small particles from the airflow. Figure 1 shows the internal view of two dry collection system boxes; one that does not use the dust collector bags and another that uses the dust collector bags. Dust collectors that use dust collector bags to contain material inside the dust collector box have been shown to provide better protection to roof bolter operators than dust collectors that do not use the bags [Listak and Beck 2008]. The dry collectors are very efficient at reducing respirable coal mine dust exposure from roof bolting activities. Recently, Blue Mountain Energy’s Deserado underground coal mining operation, outside Rangely, CO, made a modification to the dry collector system to convert it to a wet collector system with a unique exception from the Mine Safety and Health Administration (MSHA) for testing purposes. The wet collector system still uses a vacuum system to pull material from the vertical roof bolt hole, but incorporates a water spray nozzle located inside the dust box to wet the incoming material. The flow through the nozzle ranges from 1.9–7.6 lpm (0.5–2.0 gpm) at 0.69 MPa (100 psi). The conversion to the wet collector system removes the precleaner and the cyclones inside the dust box. The wet material (sludge) then empties through a specialized valve in the bottom of the box. The final filter is still used to prevent respirable dust from leaving the dust box through the exhaust. During operation, the wet collector dust box is opened and hosed clean after roof bolting every place. After every two entries the final filter is changed out. Figure 2 shows the inside of the wet collector box.

Jan 1, 2019

By Kwadwo Osseo‑Asare, Isehaq Al‑Nafai

The hydrometallurgical processing of bastnasite is a well-known process that is used to extract rare earth metals. However, more accurate measures are required to enhance the efficiency of extracting and recycling rare earths. In this work, Pourbaix (Eh–pH) diagrams for La-, Nd-, and Pr-(F)-(CO3)-(SO4)-(Cl)-(NO3)-(C2O4)-H2O systems were theoretically derived to investigate the stability relations during the hydrometallurgical processing of bastnasite. The diagrams for RE-H2O systems show similar trends to the original ones drown by Pourbaix. The stability domains of RE carbonates were presented by RE-CO3-H2O systems with pH range of 4.5–11. In contrast, the diagrams for RE fluorides showed a large stability region of insoluble REF3 (pH ~ − 1.7–12). The decomposition behaviors of REFCO3 were studied by constructing Eh–pH diagrams for RE-F-CO3-H2O system. The stability regions of bastnasite species extend from nearly neutral to basic media (pH ~ 6.5–12). The acid treatment (using H2SO4, HCl, and HNO3) of bastnasite was investigated by constructing Eh–pH diagrams for REF- CO3-(SO4)-(Cl)-(NO3)-H2O systems. According to these systems, REFCO3 can be decomposed at pH ~ 6.5 when treated with H2SO4 and at pH ~ 1.7 when treated with HCl and HNO3 acids. On the other hand, the alkaline treatment of REFCO3 converts it to RE(OH)3 at pH ~ 11. The recovery of rare earths ions was studied with the aid of RE-C2O4-H2O systems which shows a wide stability region for RE oxalates in pH range of − 2–11. This theoretical approach explained the aqueous relations in the hydrometallurgical processing of bastnasite ore and it can improve the practical hydrometallurgical processing of such ores.

Feb 9, 2024

By A. E. Isaacson, T. H. Jeffers

The U.S. Bureau of Mines (USBM) is investigating arsenic removal from dilute waters using a biological precipitation/chemical adsorption system. The method includes (1) inoculating water with ferrous salts to increase hydrogen sulfide generation by indigenous sulfate-reducing bacteria, (2) utilizing the hydrogen sulfide to precipitate the bulk of the arsenic as arsenic sulfide, and (3) using beads containing ferric oxyhydroxide to remove the remaining arsenic. This approach was applied to a contaminated water containing 13 mg/L As. Arsenic extractions up to 99% were achieved. The use of sulfate-reducing bacteria is particularly warranted in this situation since most of the required nutrients are present in the water. Based on successful initial efforts, planning is underway to conduct a pilot-scale test at the site.

Jan 1, 1995

By J. Baz-Dresch

A custom-designed shotcrete system, consisting of an 8-m3 (10-yd3) transit mixer and a shotcrete spray boom carrier, is used bya 2-man crew to transport and place up to 25 m3 (32 yd3) of steel-fiber reinforced, dry, silica fume shotcrete per II-hour shift. Shotcrete is custom blended by a local supplier and delivered predampened. Mix design and quality control is performed with a computer program that develops and graphs a properly balanced mix based upon the materials sieve analyses.

Jan 1, 1991

By N. Kuyucak

While Acid Rock Drainage (ARD) occurs naturally, its management poses challenges especially at the decommissioned sites. Two passive systems were designed and implemented at two different decommissioned mining sites in Canada in order to treat the seepage with ARD characteristics. One seep originating from a reclaimed tailings pond was neutral mine drainage (NMD) containing circumneutral pH and dissolved metals (e.g., nickel, zinc) in elevated concentrations. The other ARD from a tailings stack showed net acid drainage characteristics with low pH and higher metal concentrations than regulated limits. Due to the different ARD characteristics occurring at each site, different types of treatment systems were designed and implemented. Both sites experience extreme winter conditions. The NMD has been treated mainly by limestone drain and aerobic systems since 1997. The acid ARD has been treated by a system consisting of an anaerobic sulfate reducing bacteria (SRB) cell, an aerobic cell and a limestone filter since 2004. As this site has no access roads, space, or power, a significant capital cost as well as sludge disposal/storage requirements would have been required to institute a chemical (active) treatment system. Both systems have been successfully treating seepage and producing a water quality year round that could comply with regulated objectives.

Jan 1, 2010

By Robin Dill, Wei Song, Andrew Perham, Leo Martin

"AECOM completed a subsurface exploration program for an 18-foot diameter, approximately 4-mile long rock tunnel project in Hartford, CT. The tunnel crosses the regional geologic trend through the middle of a sedimentary basin, passing through four separate rock formations, including two volcanic flows. Faulting is prevalent, with at least 15 faults encountered during the site investigation. Severe artesian flows were also experienced in several of the borings, requiring highly specialized drilling equipment. Sixty-two borings and associated testing were performed to characterize the structural geology, hydrogeology, rock properties and ground conditions. A phased program was carefully planned and implemented with participation of geotechnical and geologic specialists, with thoughtful evaluation along the way to react to the ground conditions encountered, and make appropriate refinements. This paper will discuss the subsurface program details; the integrated efforts used to effectively characterize the ground; and will summarize the final characterization presented in the GBR. PROJECT DESCRIPTION The South Tunnel Conveyance and Storage Tunnel project is part of the Metropolitan District (MDC’s) Long Term Control Plan to address discharges to various water bodies throughout the greater Hartford area. This program includes a main conveyance and storage tunnel; a tunnel boring machine (TBM) launch shaft and retrieval shaft; adit tunnels with associated drop shafts and connection structures; consolidation conduits and manholes; and a tunnel pump station (TPS) at the downstream end of the main conveyance tunnel. AECOM is serving as prime designer for the MDC on this project. The main conveyance tunnel (hereinafter referred to as the “South Tunnel”) will be a deep rock tunnel with an invert depth of approximately 180 feet at its downstream end and approximately 218 feet at the TBM retrieval shaft. The tunnel will have a finished diameter of 18 feet. The tunnel will rise in grade at a slope of 0.1 percent to its upstream end. Total invert depth along the deep tunnel alignment ranges from about 180 ft. to as high as 320 feet. The total length of the tunnel will be 21,754 feet. The South Tunnel will be constructed using a shielded TBM and fully lined with pre-cast concrete segments."

Jan 1, 2016

By C. Vass, A. Noble

"The chemical treatment of mine-influenced waters is a longstanding environmental challenge for many coal operators, particularly in Central Appalachia. Mining conditions in this region present several unique obstacles to meeting NPDES effluent limits. Outlets are often located in remote areas with challenging terrain where conditions do not facilitate the implementation of large-scale commercial treatment systems. Furthermore, maintenance of these systems is often laborious, expensive, and time consuming. Many large mining complexes discharge water from numerous outlets, while using environmental technicians to assess the water quality and treatment regime multiple times per day. As an alternative solution, this paper describes the ongoing research and development of automated chemical treatment systems for mine water discharges. The current work explains the development of a bench-scale prototype that has been used to evaluate various monitoring, notification, and control strategies. Results from this testing are compared to present day practices to show the costs and benefits of implementing an automated treatment and monitoring program. INTRODUCTION Background The National Pollution Discharge Elimination System (NPDES), per Section 402 of the Clean Water Act, requires permitting of all point source discharges from coal mines. This program dictates that all water leaving a permitted boundary, whether it be process water or storm water, must leave through a monitored NPDES outlet. These permitted NPDES discharge points, also denoted outlets, outfalls or monitoring points, must meet a rigorous set of effluent limits to maintain compliance. Common effluent limits monitored by coal companies include but are not limited to iron, manganese, aluminum, total suspended solids (TSS), and pH. Raw mine water is often deficient in meeting these effluent limits, and as a result, various treatment processes are required to bring the water into compliance prior to environmental release. Depending on the mining and geologic conditions, water monitoring and treatment programs can constitute a significant operating cost for the mine operator. In Appalachia, acid mine drainage (AMD) constitutes one of the most significant and widespread water quality challenges that must be treated per NPDES guidelines. AMD is a general lowering of water pH that occurs when water and sulfide minerals interact within oxidizing conditions in coal and metal mining. Acid Rock Drainage (ARD) is a similar term that applies more generally to non-mining causes such as highway construction and other large-scale excavations. Today, mine influenced waters (MIW) is becoming more popular as the general term referring to all types of mining-induced water issues. AMD has been researched substantially over the last 30 years, with investigators studying various causal mechanisms and treatment strategies (e.g. Gazea, 1996; Ziemkiewicz, 1998; Skousen, 2000; Kleinmann, 2001; Johnson, 2003; Akcil, 2006; Kalin, 2006). This research has produced several pragmatic results, which provide numerous methods to predict, prevent, and treat AMD."

Jan 1, 2016

By Ihsan Berk Tulu, Ted Klemetti, Deniz Tuncay

Accurately estimating load distributions and ground responses around underground openings plays a significant role in the safety of the operations in underground mines. Adequately designing pillars and other support measures relies highly on the accurate assessment of the mining-induced loads, as well as the load-bearing capacities of the supports. There are various methods that can be used to approximate mining-induced loads in stratified rock masses, both empirical and numerical. In this study, the numerical modeling approach recently developed at West Virginia University, which is based on the modeling approach developed by the National Institute for Occupational Safety and Health (NIOSH), is investigated using the finite difference software FLAC3D. The model includes the longwall panels, the adjacent chain pillar systems, and the different stratigraphic layers of the overburden. Using the 3D model, changes in loading conditions and deformations on the areas of interest, induced by an approaching longwall face, can be examined. This paper details the 3D modeling of a longwall panel utilizing this approach, and the verification of the results against field observations. The studied panel was 360 m wide with a 3-entry chain pillar system and about a 160-m average overburden depth around the studied area. The overburden strata consist of alternating layers of shale, sandstone, and limestone. The FLAC3D results were compared against field measurements from the mine site. The stress change values measured in the chain pillars were comparable with the modeling results. The model also replicated the surface subsidence profile obtained from field measurements fairly well. Overall, the 3D modeling approach was found to be successful for the case study longwall panel.

Sep 23, 2020

By D. R. McMullin

The purpose of this paper is to provide a method for mine planners and engineers to evaluate on a conceptual basis if a shaft or a ramp is most suited for their particular underground access requirements. Mine planners and engineers are often raced with the decision of choosing which method of underground access is best suited for their particular requirement. Underground access can be provided by a shaft, ramp, adit, or slope for either exploration and/or actual production operations. This paper will focus on the construction cost and schedule differences between sinking a shaft and excavating a ramp which are currently the most typical access alternatives used in the western United States. It would be wrong to state that one method is superior to the other in every case. There are many variables to be addressed, and the degree of sensitivity of each of them will eventually dictate which method is the most suited to the particular circumstances. This paper compares the construction cost and schedule or sinking a shaft to excavating a ramp at different depths given different ground and hydrological conditions. This comparison provides mine planners with "rules or thumb" that may be applied to the access selection process.

Jan 1, 1994

By J. G. Groppo, B. K. Parekh

A series of performance studies were conducted using countercurrent column flotation to recover a marketable clean coal product from existing preparation plant fine waste streams. The test work was conducted at several preparation plant sites in Kentucky and Virginia using a 150-mm (6-in.) inside diameter column that was 5.8 m (19 ft) high. Both thickener feed and classifying cyclone overflow with a typical size distribution of 150 µm (100 mesh) X 0 were tested. The percent solids of the column flotation feed varied from 1.5% to 15% while the ash content ranged from about 30% to 60%. The concentrates produced contained 2% to 10% ash with Btu recoveries of nearly 90% using 0.12 to 1.25 kg/t (0.25 to 2.5 lbs per st) fuel oil and 0.12 kg/t (0.25 lbs per st) MIBC. These results were consistent with or better than results obtained in preliminary laboratory scale column flotation evaluation. Test results from seven different seams are discussed as well as scale-up relationships used to design a full-scale installation presently in operation.

Jan 1, 1991

By T. Emery, D. Sweet, J. Bourgeois, B. Seymour, D. Porter

Cemented rockfill (CRF) is being used to backfill primary and secondary stopes at the Eagle Mine, an underground nickel and copper mine operated by Lundin Mining. National Institute for Occupational Safety and Health (NIOSH) researchers from the Spokane Mining Research Division (SMRD) are conducting cooperative research with the mine staff to determine if the size of a CRF sample affects its measured strength properties. Based on previous research by NIOSH, cylindrical samples of CRF ranging in size from six to eighteen inches in diameter were cast at the mine and cured underground. The samples were later transported to the SMRD laboratory and the Michigan Technological University where tests were conducted to determine the strength and elastic properties of the CRF. To further analyze the relationship between backfill density and compressive strength, different ASTM International compaction techniques were used to cast the samples. For comparison, tests were also conducted on in-situ core samples that were drilled from a stope which had been backfilled with the same CRF mix. The data collected from this study not only improves our understanding of CRF in-situ properties but also helps optimize Quality Assurance/Quality Control (QA/QC) methods for backfill preparation and testing.

Feb 1, 2023

By Donna Wallace

Past EPA groundwater monitoring programs required that contamination not leave the boundaries of a disposal facility. New regulations under the Resource Conservation and Recovery Act (RCRA) require that once hazardous waste constituents are detected beyond the limits of the disposal area, a program to define the rate and extent of contaminant migration must be instituted. Future regulations are likely to include even more stringent groundwater protection criteria. The implications of both the existing and probable future groundwater protection and monitoring requirements in terms of using geologic containment as a means of disposing of hazardous waste are explored in this paper.

Jan 1, 1981

By R. A. Wyman

What unusual features are there about finding, winning, and using the industrial minerals of Canada which may be of interest and yet not widely known. Have you, for example, ever wondered where the raw material for those distinctive greenish grey statuettes, so readily recognizable as Eskimo carvings, comes from? Although stone suitable for carving is obtained at several northern locations, in recent years the Federal government, the Quebec government, and one or two private companies have shipped supplies of various rock types from other sources to central distribution points in the Canadian north for the express purpose of providing Eskimo artists with raw materials for carving. Canada is well endowed with industrial minerals, the extent and variety of which may be observed by a perusal of Table 1. In this table, materials currently produced are shown in the left-hand column; materials which are bordering upon economic viability are listed in the middle column; and materials which have been found in Canada in possible exploitable quantity, but for which [ ]

Jan 1, 1970

By R. S. Hearon

The image of the open-pit miner in the eyes or the Environmentalist has never been very outstanding. The phosphate industry, whose history in Florida reaches back to the late 1800's, can-not be credited until recently with a large number or accomplishments in terms of protection or the environment to change this image. This lack of action was not deliberate or in opposition with the desires of the public. In the formative years, there was little or no public and the companies found it necessary to build towns to house their employees and their families, towns which remained in existence until the late 50's and early 60's or formed the core of present large communities. Neither these pioneers nor most subsequent resource developers considered themselves un-thinking spoilers, nor were they so regarded by their contemporaries. Instead, they acted in a manner consistent with their environmental circumstances and intellectual heritage. Early Americans did make mistakes in using the land but the mistakes became apparent only in the opinion of later generations. Over the past five to ten years, there has been a new self-awareness in the industry with regard to environmental responsibilities brought about, in part by a continuing onslaught of new regulations with jurisdiction over our activities. Part of the new regulations are aimed at industries as a whole while many, particularly state regulations, pertain specifically to the phosphate mining industry. Why all the new regulations? The reasons are encased in a complex web of activity but stem primarily from a new public awareness of its environment. More and more of our youth have become interested in the environmental science areas such as biology and ecology. The tremendous growth rate in both the population and industry has made personal issues out of subjects such as atmospheric inversions and water shortages which previously were abstract concepts. The State has grown from a population of 1,500,000 in 1930 to approximately 9,000,000 people today. This personal impact and general lack of knowledge on the part of the public concerning economics has resulted in big business no longer being held in awe, often in contempt and generally in suspicion where environmental concerns are encountered.

Jan 1, 1978

By S. Angioletti

This paper addresses strategic investment decisions when they are nested in a project development format where each project is implemented in phases and each phase is approved to move on to the next phase only if certain technical and economic requirements are met. This configuration is sometimes referred to as a ?Project Portfolio?. Mining companies maintain project portfolios in their exploration investment plan. This study proposes a procedure to best manage an exploration project portfolio including technical and economic uncertainties. The procedure may support decision makers in a simple and intuitive way, while maintaining the rigor and precision required by the rather large amount of financial resources typically called for by mining projects. The procedure was tested in a real case study of a gold mining company and its exploration projects portfolio. The procedure uses the following approaches: i) investment valuation methods under technical and market uncertainties based on Option Pricing Model, Real Option Theory and Option Space; ii) portfolio management and Stage Gate®1 method; iii) Monte Carlo simulation.

Jan 1, 2010