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By M. G. Mudrey

Considerable potential for metallic mineral resources in the lower Proterozoic rock of the Lake Superior region exists (Mudrey and Kalliokoski, in press). Most of the identified resources occur within a 2.0- to 1.9-b.y.-old lithotectonic assemblage characterized by extensive sedimentary strata in the north and thick volcanic se- quences in the south, all deposited on a two-terrane, composite basement of Archean age (DeMattis, 1989). Since the late 1960s, measured resources of nearly 90 Mt (100 million st) of typical volcanogenic massive sulfide at eight localities in Wisconsin have been discovered. The largest of these, near Crandon, contains about 61 Mt (67 million st) of ore averaging 5.6% zinc, 1.1 % copper, and 0.5% lead. Although none of these properties are in production, estimates by Mudrey (1978) suggest that Wisconsin could become a major contributor of newly mined zinc and copper in the United States. These discoveries and uranium and gold discoveries in the Canadian Precambrian are what have led to in- creased metallic mineral exploration throughout the northern half of Wisconsin (Fig. 1). In this chapter, we discuss the geology and legal framework in which the Proterozoic volcanogenic massive sulfide deposits were found. Exploration activities for other metals have generally been negative, and have been background noise for the legislative activities related to the massive sulfide discoveries. Uranium exploration has been consistently negative, although several different environments have been assessed. Other metal discoveries. such as titanium/vanadium, have been subeconomic.

Jan 1, 1991

By R. M. Hernandez

The Bureau of Land Management (BLM) constructed four passive biochemical reactor systems (BCRs) to treat mining influenced water (MIW) in the Bunker Hill Superfund area near Coeur D?Alene, Idaho between 2002 and 2003. Initially, the BCRs operated very effectively. However, in the past couple of years, the zinc removal effectiveness of the four BLM BCRs has declined [1]. The central objective of this study was to characterize the microbial communities and substrate present within the BLM BCRs and to use these factors to propose strategies to promote sustained sulfate reduction levels. Microbial communities were characterized by quantifying total bacteria and sulfate reducing species. Substrate was characterized by quantifying the percent organic, acid soluble organic, acid insoluble organic, and bioavailable material within the BCR. The results suggest the depletion of bioavailable organic substrates is the primary cause of the decline in zinc removal and not the microbial community structure. The ability to assess the amount of bioavailable organic substrate and microbial community is important to the understanding of the sulfate reducing capacity of the BLM BCRs and developing strategies to facilitate performance enhancement of the current BLM BCRs. The characterization of organic substrate and microbial community structure are also important to improving design of future passive treatment systems for mining influenced waters.

Jan 1, 2010

By S. Koro

The current economic climate of low commodity prices and increasing costs has put a lot of pressure on mining companies to ensure their operations will survive through the current economic downturn. While history tells us that the cycle will turn around and prices will go back up again, how many mining companies will be left to take advantage of the next upturn? On average in Australia, the maintenance of mining equipment accounts for up to 50% of operating costs; which equates to nearly $15bn per year. In addition to trying to boost productivity, mining companies are also putting a lot of pressure on reducing costs; all with the intention of maintaining/increasing profit margins and thereby keeping shareholders ?happy?. The whole premise of our economy is based on ?growth? and ?profits?. Movements in the market place force mine owners to ?react? to short term fluctuations. And if that movement is downward; operations people at the sites are forced to start reducing costs. Is this cost reduction done in a logical, systematic way where all risks (short-, medium- and long term) are considered? Invariably, the answer is no! Short term ?fixes? are normally implemented with little, or no, regard for medium- and long-term impact. And the reason for this is that management is not fully focused on the long term; focus is mainly on survival. Decision making is driven by shareholder sentiment and history tells us that this is largely short-term. So given these paramteres to work within, what role can ?Asset Management? play in assisting management to meet shareholder and market requirements whilst still maintaining long-term viability of their operations (to the long-term benefit of shareholders dare I say). As maintenance costs account for nearly half the operating costs of mining companies; the ?smart? management of assets is not only crucial; it is essential for survival in today?s economic climate. What is asset management? Asset Management, according to the UK-based Institute of Asset Management (IAM) is ?the systematic and coordinated activities and practices through which an organization optimally and sustainably manages its assets and asset systems, their associated performance, risks and expenditures over their life cycles for the purpose of achieving its organizational strategic plan.? How important is asset management in today?s mining companies? IAM goes on to say: ?This definition of asset management represents a significantly greater scope than just the maintenance or care of physical assets, and is closer to the central purpose of an organization. Good asset management considers and optimizes the conflicting priorities of asset utilization and asset care, of short-term performance opportunities and long-term sustainability, and between capital investments and subsequent operating costs, risks and performance. ?Life cycle? asset management is also more than simply the consideration of capital costs and operating costs over pre-determined asset ?life? assumptions. Truly optimized, whole life asset management includes risk exposures and performance attributes, and considers the asset?s economic life as the result of an optimization process (depending upon the design, utilization, maintenance, obsolescence and other factors).?

Feb 23, 2014

By M. G. Rylatt

The Ekati process plant flowsheet features the common steps in diamond recovery plant design. Primary treatment and concentration is by crushing, scrubbing, high-pressure grinding rolls and heavy medium separation (Fig. 1). Secondary concentration is by an attrition mill; wet, high-intensity magnetic separation and X-ray sorting (Fig. 2). All of these are performed on site, although final sorting of the diamonds into commercial categories will be carried out elsewhere. The initial throughput rate is 9 kt/d (9,900 stpd), increasing to 18 kt/d (20,000 stpd) during the first 10 years of operation. A range of ore characteristics will be encountered that will effect the plant operating conditions during the life of the mine. The adopted design envelope is based on these expected variations. The design is based on the use of large-scale equipment, incorporating the latest and most efficient technology available. Where proven technology exists, no attempt was made to reinvent the wheel. However, where recently developed technology offers a significant advantage, this has been incorporated into the design. The Ekati run-of-mine (ROM) and coarse ore handling facilities are unheated, to take advantage of the better handling characteristics of the frozen ore in winter. The stockpile reclaim features an MMD mineral sizer (a toothed roll crusher) to minimize the problems of handling thawed, sticky kimberlite in the summer and break frozen lumps in the winter. All processing downstream from primary crushing and the coarse ore stockpile is carried out in a temperature-controlled environment in the main process plant building. Personnel involvement in the process is mini¬mized by using a Modicon Quantum series PLC with human-machine-interfaces (HMI) running Wonder-ware software on dedicated personal computers.

Jan 1, 1999

By Ali Yalçin

The study area is located in the NW of Uluborlu (Isparta). Massive limestones and alluvial deposits form the lithological units of the study area. The average thickness of the alluvium deposit consisting mainly of light brown - red colored and fine grained clastic sediments which derived from the limestone is about 10 meters. The aim of this study to investigate the uses of this alluvial sediments as tile - brick material. For this aim, disturbed and undisturbed samples have been taken from different depths in the alluvial deposits. Mineralogical compositions have been determined by XRD and major oxide contents by XRF. Laboratory experiments have been carried out to determine the technological properties of the samples. The selected major oxide contents of samples vary between A12O3 (24.6 - 24.12 wt %), CaO (0.76 - 4.27 wt %), Fe2O3 (10.21 - 10.29 wt %), MgO2 (1.25 - 1.51 wt %). CaCO3 and MgCO3 values calculated from the geochemical analyses, are between 1.55 - 1.62 and 2.62 - 3.17 respectively. The ratios of grain size of the samples are 82 % for < 0.2 mm and 5 % for > 3 mm. Geochemical analyses and technological features of the samples indicate that these fine grained sediments of alluvial deposit are suitable in terms of uses as tile - brick material. The potential reserve of this tile - brick material has been determined as 40 million tones.

Jan 1, 2005

By Jerome A. Westphal

The Middle Mississippi River extends from the mouth of the Ohio River to the mouth of the Missouri River, a distance of about 310 kilometers (km) measured along the river. From its founding in 1764 to the first steamboat arrival in 1817, the City of St. Louis was little more than a trading post. However, with the advent of the shallow-draft steamboat, the Middle Mississippi River rapidly became a major thoroughfare of commerce. In this regard, its importance has been reflected by the development of port facilities at St. Louis and by Federal activity relating to channel maintenance and improvement. First Federal work on the Middle Mississippi River was autho¬rized by Congress in 1824. This work was for snag removal and bank clearing and was directed at reducing the hazards to steamboat traffic, particularly during low-flow periods. During the 1820&apos;s and early 1830&apos;s, the main channel threatened to move toward the Illinois shore and abandon the St. Louis port facilities. In 1836 and 1837, Congress authorized construction of permanent improvements to keep-the river next to St. Louis (Missouri shore). By 1880, it was recognized that bank clearing activities had resulted in a wider and shallower river which exacerbated navigation

Jan 1, 1977

By John O. Marsden

Technology development has played a crucial role in the minerals industry throughout history. The development of new technology allows mankind to produce metals and minerals at progressively lower cost of production in real terms, and therefore at progressively lower prices, improving their availability, accessibility and utilization worldwide. However, the developers of such technology are not guaranteed to reap the benefits from this effort: There is an expectation that technology developers will gain an advantage over their competitors. Is this a short-term benefit that results from a temporary cost or efficiency improvement, or is it a sustainable longer term "edge" that prevails even after metal or mineral price has been eroded by the implementation of a major step change technology? This issue is examined by reference to several case study examples in the copper industry. BACKGROUND The development and adoption of new technology has played a crucial role in the commodity minerals industry throughout history. As new, cost-efficient technologies are commercialized, the cost of production decreases, and this enables lower grade ore to be processed profitably. This in turn increases the availability and supply of the metal or mineral of interest, and ultimately (in a free market environment where the supply- demand balance determines price) inevitably decreases the metal or mineral price. This leads to the question: Why should mining companies invest in (new) technology development if the result is a decrease in the product price? The answer is to achieve competitive advantage, where the application of new technology enables one or more

Jan 1, 2004

By P. G. Irwin

Natural resins, those derived from coal and those mined in the Uintah basin, face challenges from synthetic resins that are derived from petroleum sources and rosin or wood sources. In the past, fossil resins from coal were produced by various companies, the last one being Hercules, Inc., which sold BLACKHAWK resin until a fire destroyed the plant in the mid 1970&apos;s. Approximately four to fjve million pounds of BLACKHAWK were produced and sold mostly to the printing ink industry. Uintaite, more commonly known as Gilsonite® resin, was widely used by various industries, notably in printing inks, coatings, stains, adhesives, foundry, asphalt paving, and oil well drilling muds. Gilsonite has lost market share over the last thirty years to various synthetic resins particularly hydrocarbon resins that are derived from petroleum sources.

Jan 1, 1990

By James P. Savely

This paper describes the development of a trim blast design to improve the stability of a final pit wall. Description is given of the effects of rock characteristics, rock type, and pit plans on the blast design. Currently, six benches have been mined with trim blasting. A more stable final wall has resulted and the successful program has reduced mining costs over an extended time period. Low cost blast monitoring and field observation were used to determine peak particle velocity and blast damage. Using criteria developed from this relationship, trim blasts were designed and evaluated.

Jan 1, 1986

By K. Fleck

Energy West Mining Co. (EWMC) has implemented a geologic program for improving stability and support requirements along deep two-entry longwall gateroads at its Deer Creek Mine operations located near Huntington, UT. Together with geotechnical monitoring and concurrent review of mine seismicity in cooperation with MTI staff, it has become possible to improve longwall layout designs for two seam extraction of the Hiawatha and Blind Canyon seams. The geologic program consists of surface and in-mine exploration drilling, surface and in-mine geologic mapping, rock mechanics testing and detailed measurements of changes in depositional and structural conditions during development of every longwall gateroad. The geotechnical program consists of underground measurements at seven locations in two neighboring mining districts located in the Hiawatha and Blind Canyon coal seams under moderate to deep cover. Within the last five years, additional measurements, including data on seismicity and face conditions, have been incorporated into the data collection program for verifying the in situ coal strength and load transfer mechanisms for improving two-seam designs and support systems.

Jan 1, 2012

By Peter N. Yanker

The two types of dryers used in the drying of copper concentrates are the rotary dryer and the spray dryer. The rotary dryer has until recent history been the traditional drying method used, Although spray dryers have been used in the chemical field for many years it is only recently that they have been accepted for drying of copper concentrates. The comparison made here will apply in a narrower sense to the drying of copper concentrates as fed into the reverbatory furnaces of the Smelter. To compare a rotary dryer and a spray dryer, which are two totally different methods and pieces of equipment, it is best to view them as systems each made up of certain elements

Jan 1, 1976

By B. C. Lewis

The mining industry has experienced a general trend toward an increasing number of longwall operations, an increasing percentage of underground coal being mined by longwalls, and increasing productivity from the longwalls. Longwall operators have not yet reached a state of mining euphoria. Competitiveness both within the industry and from alternate fuel sources is forcing continued pursuit of higher productivities and lower costs. The following graphics present trends in the industry. Longwall mines, as defined for this presentation, are those reportedly having longwall installations in each of the respective years. Production from both the continuous miner and longwall units is included in the longwall mines. Non-Longwall mines are all other underground mines. Productivity calculations are based on total employee-hours associated with the operation.

Jan 1, 1990

By J. S. Lewis

Beneficiation and physical and chemical processing of non-terrestrial materials borrow strongly from terrestrial experience, but also involve the necessity of handling literally un-Earthly feedstocks, reagents, and environmental conditions. The present state of scientific and engineering understanding of the processing of non-terrestrial minerals, gases and hydrocarbons is reviewed with the production of rocket propellants, life-support fluids, structural metals, and refractories as the goal.

Jan 1, 1992

By Behzad Khorshidi

"The ultimate objectives of the post-tensioned strands are to connect the precast segments into a ring and provide pre-stress in the tunnel circumference. The method involves inserting the strand through the preliminary embedded duct in the precast concrete segments and then tensioning the strand by jack and fastening it. The post-tensioned strand eliminates the necessity of bolt connections between the segments and may reduce the labor cost and increase speed of lining construction. Pre-stressing of the segmental lining reduces the steel reinforcement or fiber volume in precast segments and/or thickness of the precast segments which would result in reducing the manufacturing cost of them. Pre-stressing would reduce cracking and increase water tightness, and would provide smooth intrados due to eliminated bolt joints and pockets in the tunnel lining. Pre-stressing would increase resistance to internal pressures as well. Further, this system could work very well structurally in tunnels with squeezing rock or tunnels with high seismic loadings. INTRODUCTION OF THE METHODPost-tensioning is commonly used in the construction of bridges, large buildings, nuclear power stations, and water tanks but its utilization in tunnels is still in its infancy.The precast pre-stressed concrete segmental lining can be used for shield tunnels. It provides a reinforced lining ring by the following construction stages and as shown in Figure 1:1) Segments to be assembled by TBM to complete a full ring2) Steel strand to be inserted through embedded duct (sheath) within the segments3) The strand to be tensioned by Jack after anchorage of the other end4) The strand to be fastened after reaching required tension load5) The horizontal strands (if necessary) to be installed, tensioned and fastened6) The recesses and gap between strand and duct to be filled by groutingFurther, Figure 2 shows an unbonded post-tensioning strand model; Figure 3 shows an anchor sample (Xanchor); Figure 4 shows a duct (sheath) and anchor within reinforcement; Figure 5 depicts the posttensioning of a strand by jack; and Figure 6 is an image of the Midorigaoka Trunk line tunnel in Sagamihara, Japan which was constructed using this system."

Jan 1, 2016

By C. L. Schneider

The calculation of the liberation spectrum in the product from continuous milling operations is a problem of considerable importance and is difficult to solve because the population balance equation must be integrated in two-dimensional space. Complete solutions require the estimation of a large number of parameters unless a structural model of the ore texture can be used. A very simplified textural model based on the use of the modified Andrews-Mika diagram and the PARGEN simulation of multi-phase particles has been formulated and is used to simulate the behavior of a continuously operating laboratory ball mill. A sensitivity analysis for this mill has been done to show the likely effect of model approximations on the predicted liberation spectrum which will be measured.

Jan 1, 1992

By James A. Decker

Hanna has developed three production planning systems to help the mine engineers determine the sequence of mining from available ore supples. The Production Scheduling System was developed to give the staff a tool for long range planning by sequencing the removal of blocks from an open pit property. It was needed to determine the year of removal for each block so that the optimum present-valued pit limits could be established by our pit design program. Since in this type of planning short term grade control is less of a factor than it is in daily or monthly planning, the system gives the program greater control and more latitude in block selection. It permits only full blocks to be taken.

Jan 1, 1984

By Mark Alan Marlkos

Blebs of solid bitumen from the Magmont West orebody of the Viburnum Trend were examined and analyzed in an attempt to relate hydrocarbon distribution and origin to ore genesis. The bitumen was calculated to be approximately 48 to 63 percent aliphatic and is considered to be a polymerized normal crude oil. Polymerization, which was probably caused by water-washing, hardened the bleb surfaces and appears to have "frozen" the blebs during primary migration from local source beds. Comparison of the bitumen to kerogen in local shaly partings strongly Indicates that the oil was derived locally. The polymerized oil blebs are considered to have been derived from a type II (marine) kerogen. Textural analyses indicate that oil migration occurred after lead-zinc mineralization and at temperatures that exceed normal ancient or present geothermal gradients. The following sequence of events is postulated for the Magmont West orebody: 1 Generation of hydrogen sulfide during diagenesis of a normal organic-rich carbonate sequence. 2 Introduction of pulses of hot, metal-rich fluids that resulted in: a Lead-zinc mineralization by the following reaction: Me++ + H2S ? MeS + 2H+ b Solution of carbonates by excess acid produced during the above reaction. c Brecciation of host rock in some cases. 3 Passages of the pulse resulted in: a Carbonate buffering of fluid system to more alkaline conditions. b Precipitation of dolomite c Slight temperature drop. 4 Eventually the high temperatures Introduced by heated brine caused oil generation and initiated primary migration. 5 Water-washing and mild biodegradation altered the hydrocarbon blebs to their present composition.

Jan 1, 2013

By J. F. T. Agapito

Two flat-lying trona seams 3-to 3.5-m thick, approximately 10 m apart, and at depths of 250 m are mined by room-and-pillar at OCI&apos;s Big Island Mine in Wyoming. Continuous miners and a yielding pillar system have contributed to improvements in resource recovery and productivity. Long-term stability with minimal subsidence is needed for a large portion of the mine beneath the Green River channel. This was investigated by computer modeling in 1990. Although results of the study indicated good long-term stability, recommendations were made for stress determinations to verify the model. Stress determinations made in 1997 showed pillar stresses 10% to 20% higher than the model stresses, and barrier pillar stresses 10% to 15% lower. This implies that higher panel stresses will be transmitted from the upper to the lower seam. A stability evaluation of the lower seam is planned before two-seam mining to assess entry widths and support requirements.

Jan 1, 1999

By Frank H. Buchella

Principal factors influencing equipment selection can be grouped into five basic categories. Tonnage Requirements, Ore and Waste Loading, transporting, and ground preparation equipment are largely determined by tonnage requirements. Generally, the greater the tonnage requirements, the larger the equipment size selected. Large size equipment is appropriate for a production of about six million tons (total) per month, medium size for three mil- lion tons, and small size for one million tons or less.

Jan 1, 1973

By James J. Brady, James S. Lewis, Robert B. Gordon, Jimmy W. Honeycutt

INTRODUCTION Tunnel construction has always been an extremely high risk form of contracting primarily due to the inaccessability of information concerning the ground conditions to be encountered during excavation. We certainly make every effort to overcome this problem through borings, geological research, site visits, etc.; but at best owners, engineers and contractors alike are only able to interpolate a relatively small amount of factual data from isolated sections of the project into a forecast of ground conditions for the entire project. In essence this becomes an "educated guessing game" with risk to reward ratios (and subsequently the bid price) in direct relationship to the contractor&apos;s confidence in the quality of the guess. In many instances it is economically or physically infeasible to obtain information and of course the total picture is never known until the project is complete. This problem effects the contract format as well as price. The contractor&apos;s ability to handle unforseen problems on the project become extremely important as to the project&apos;s overall success. The following pages contain an actual case history of a project which affords an excellent example of the entire spectrum of situations resulting from tunnel construction in difficult ground conditions.

Jan 1, 1983