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By J. K. Gowans

"INTRODUCTIONTo bring a mining property into production in the Canadian High Arctic a company must deal with the harsh environment, the short shipping season and the high cost of labour. In trying to minimize the effect of these factors, the concept of a barge-mounted process plant was investigated as an alternative to the conventionally built concentrator. Cominco's previous experience gained at the Black Angel Mine on Greenland's west coast suggested that this would be a practical alternative.The normal shipping season at Little Cornwallis Island is approximately six weeks long, from mid-August to the end of September. All equipment and materials must be delivered during this small ''shipping window."" The logistics problems are enormous; if the conventional approach had been used the major process equipment would have been delivered to Little Cornwallis Island at the same time as the completed barge actually was! Construction would also be starting at the start of the worst climatic conditions, the Arctic winter. Nine months production was gained by opting for the ""Barge"" approach.What the Arctic winters do to the shipping season, so do they affect the productivity and the cost of labour. Construction labour must come from southern Canada. Thus higher transportation costs and higher wage rates, with more overtime and incentives, increase the labour costs to approximately 50% over normal southern rates. Couple these rates with the lower productivity involved with men working in the extreme cold temperatures and the net effort is worth avoiding. A process plant being constructed in Southern Canada can take advantage of more accessible labour at lower costs, increased productivity and a faster construction schedule. The barge concept must still deliver the equipment and materials during the ""shipping window"" but it can in the completed form."

Jan 1, 1983

By G. C. Knutsen

The Post deposit is located in Eureka County, Nevada, about 37 km (23 miles) northwest of the town of Carlin. Post occurs on the Carlin Trend, a northwest alignment of 14 major gold deposits, each containing more than three tonnes (t) (100 000 ounces) of gold. Deposits of the Carlin Trend are epithermal, sediment-hosted, disseminated gold occurrences, collectively containing more than 622 t (20 million ounces) of gold. Three major gold producers active on the Carlin Trend are Newmont Gold Company (NGC) (12.4 t/400 000 ounces of gold per year), Western States Minerals Corporation (WSMC) and Pancana Minerals joint venture (1.56 t/50 000 ounces of gold per year), and Dee Gold Mining Company (1.4 t/45 000 ounces of gold per year). The Carlin Trend has also been referred to as the Lynn-Railroad Mineral Belt. This district is characterized by open-pit mineable, micron-sized gold, hosted in Paleozoic sedimentary rocks. Six geological subdistricts comprise the Carlin Trend, each characterized by differences in host lithology, structural controls, alteration assemblage, or style of mineralization. The six geologic subdistricts include, from south to north, Bullion (Railroad), Rain, Maggie Creek, Lynn, Bluestar-Goldstrike, and Bootstrap. With the exception of the Bullion subdistrict, which was primarily a producer of base metals, each sub-district contained mineable reserves in excess of 31 t (one million ounces) of gold.

Jan 1, 1987

By Arun Kumar Singh

Wide variation in the nature of the coal seams and the surrounding rock mass of the Indian coalfields and very little information about the associated stress fields were observed to be the major hurdles in the straight forward application of a continuous miner (CM) based mechanised depillaring approach. Due to various techno-economic reasons, a considerably large number of coal seams have been developed and are standing on pillars in India. The development of pillars is done as per Indian coal mines regulation, which results in pillars of relatively large size. In fact, the large size of the pillars provides stiff natural support to control caving of the massive overlying strata. However, the size of these pillars is not conducive for the single pass pillar stripping technique and, therefore, there is a need for pillar splitting before pillar extraction/retreating. Splitting of the pillar may reduce the competency/stiffness of the pillar, which creates a chance of overriding during final extraction below a massive roof stratum. This paper first discusses the existing coal mining scenario in India followed by a brief presentation of geo-technical details of pillar extraction at the three sites where a CM has been introduced for depillaring/pillar retreating in the country to date. Based on past rock mechanics experiences with conventional depillaring faces, stability issues of the pillars, fenders, and stumps in and around the depillaring face are discussed. This may prove to be an important factor in the success of future CM faces. It is recognized that the application of the modern strata movement monitoring techniques may improve operation safety by providing valuable qualitative and quantitative information that can be used to improve the design of modern concepts like roof bolt based breaker line support during pillaring.

Jan 1, 2009

By E Lounejeva, J A Halpin, A Chappaz, D D. Gregory, S Wu, T Lyons, P J. Sack, R R. Large, S W. Bull

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. Newly published models suggest that some orogenic and Carlin-style gold deposits formed by the remobilisation of trace elements during interaction with hydrothermal or metamorphic fluids from early sedimentary pyrite that was enriched in Au, As and Te. The released trace elements are transported by the fluids to favourable trap sites where they are deposited. Therefore, early enrichment of Au, As and Te in source rocks (particularly in pyritic black shale) can be crucial to the formation of orogenic and Carlin-style gold deposits.The most important cause of the enrichment of gold and other trace elements in the sedimentary basins has been examined in this study to determine which basins are the most prospective for the development of orogenic gold deposits. An important influence for Au and other associated trace element accumulation in sedimentary pyrite is the temporal variation of trace element content in the oceans, as revealed by a database of over 1400 analyses of pyrite from black shale through geologic time. It is inferred that sediments coeval with those where sedimentary pyrite is enriched in Au and associated trace elements are more likely to be source rocks of orogenic and Carlin-style gold deposits.Factor analysis of the trace element content of pyrite through geologic time was conducted to investigate the multivariate relationships amongst trace elements and how these chemical factors explain the uptake of trace elements. One important factor includes Te, Au, Pb and Bi content. The incorporation of these large cations into pyrite is enhanced by As3+ substituting for Fe in pyrite lattice. The As3+ ion occurs in relatively oxidised environments and, thus, it is expected that shales deposited in non-euxinic waters are better source rocks for orogenic gold deposits.The examination of both the time in which the sediments were deposited and the redox conditions of the basin, and the ocean more broadly, can be used as a guide to approximate the extent of a basin’s fertility. To illustrate the use of this exploration tool, examples from the unmineralised Jet Rock Formation (UK) and the mineralised Castlemaine Group (Bendigo, Australia) are presented in this paper.CITATION:Gregory, D D, Large, R R, Halpin, J A, Lounejeva, E, Wu, S, Bull, S W, Sack, P J, Lyons, T and Chappaz, A, 2015. Accumulation of trace elements into black shale – how to identify a viable source rock for orogenic and Carlin-style gold deposits , in Proceedings PACRIM 2015 Congress, pp 59–64 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

By Taner Sumer, H Altay Guvenir

Fragmentation in rock quarries is tried to be achieved by changing the specific charge, drill pattern and bore hole diameters by different experts. This paper is a brief summary consisting of the utilization of practical experiences of the other group on cost optimization procedure that takes into account blasting, transportation and crushing as a whole process and optimize the cost by defining the optimum gelatin based explosives to be used as a main primer of anfo in three different limestone and granite quarries, with similar rock characteristics.

Jan 1, 1993

Grinding and Flowing Investigation on Dry Stirred Ball Milling in Order to Determine the Influence of Grinding Aids Huge difficulties of the great ultra fine ground material production in dry stirred ball mill are the cohesion and agglomeration of the particles. During grinding the material stick on the grinding wall and the grinding media furthermore the grinds start cohere, making aggregation and agglomeration to appear. Due to these effects the particle size will not decrease after a certain value during grinding and the energy demand increases significantly. According to experience on fine grinding in ball mill, it is well known that these effects can be reduced with the use of grinding aids. The influence of grinding aids has three different effects: due to the adsorption strength reduction (Rebinder effect) the grinding resistance of the material decreases; the surface energy diminishes and the agglomeration liability decreases; and the flow properties of material improve. The aim of this study is to investigate the flow properties of fine grinds and the effect of grinding aids on flow properties in case of dry stirred ball milling. In addition, the influence of grinding aids was investigated based on the particle size distribution and specific surface area of grinds and the specific energy demand of grinding. The examinations were carried out with three different model materials (limestone, clinker, quartz) using the usually applied grinding aid. The flow properties were measured by the Jenike shear cell; the particle size distribution and specific surface area were measured by laser particle size analyser (Fritsch Analysette 22), grinding energy demand was measured with microcomputer controlled digital energy meter. It can be said that under certain measuring circumstances the influence of grinding aid on flow properties can be demonstrated by Jenike shear cell, so the grinding result is in correlation with the flow properties of grind.

Sep 13, 2010

An examination of the Census of Fatal Occupational Injuries (CFOI) data for the period 1992-1995 shows that 659 fatalities occurred in the mining industry as defined by the SIC. Oil and gas accounted for slightly more than one-half of all fatalities (figure 1-1). The coal industry had the highest fatality rate for the 4-year period, with 35.6 deaths per 100,000 full-time workers, followed by metal (23.1 per 100,000), oil and gas (23.1 per 100,000), and nonmetal (20.1 per 100,000). The fatality rate for all U. S. industries during this same period was 5.1 per 100,000 full-time workers. Figure 1-2 compares the fatal injury rates by year for the four major industry sectors of mining to the fatality rate for all industries combined. Figure 1-3 compares age-specific fatality rates in the mining industry to those seen for U. S. industry as a whole. Fatality rates for all industries combined were lowest for young workers and steadily increased in relation to workers' ages. In the mining industry, fatality rates by age group show a U-shaped curve. Young workers under 20 years of age had the highest injury rate (54.6 per 100,000), followed by workers aged 20-24 (50.8 per 100,000) and workers over age 65 (37.7 per 100,000). Table 1-1 shows the distribution of injuries by type of injury event. The mining industry, in comparison with all industries, had a considerably larger proportion of fatalities classified as caught in or crushed by collapsing materials (9.1% and 1.9%, respectively) and fires and explosions (10.0% and 3.1%, respectively). Transportation events comprised the largest proportion of fatal injuries in both the mining industry and all industries. Within the mining industry only, transportation accounted for the largest proportion of fatalities in all mining sectors except coal. A more detailed examination of the transportation events within the mining industry showed that highway incidents (50.5%) were the most common, followed by nonhighway incidents (22.2%), pedestrian incidents (10.6%), and those incurred during rail, water, and air transport (15.7%). Incidents involving caught in or crushed by collapsing materials comprised a higher percentage of injuries in the coal and metal sectors, while fall-from-height incidents were more frequent in the oil and gas sector. The classification system used in CFOI for type of injury event is not compatible with any variables contained in the MSHA data; therefore, direct comparisons are not attempted. [ ]

Jan 5, 2000

By J. Gholamnejad

In open pit mine planning and design, push back mine sequencing is widely used for long-term production planning. In push back design, a series of nested pits is generated and then considered as possible push backs with regard to the minimum push back width requirements. These nested pits are produced by parameterizing on one economic parameters like commodity price, mining or processing cost, stripping ratio etc. The most important characterization of these push backs is that the inner most push back has the highest value per ton, the second inner most push back has the second highest value per ton and so on. These nested pits are generated based on the best estimates of grade within a representation of the ore body in a three dimensional matrix form. Therefore, the inherent uncertainty associated with reserve estimation (for our discussion grade uncertainty) is not taken into account when push backs are designed. These methods do not attempt to establish which part of the deposit is likely to be worth most. This paper introduced a new algorithm that incorporates ore grade uncertainty during push back design process. The suggested strategy tries to seek to schedule risky blocks later in the extraction sequence.

Jan 1, 2007

By Michael A. Markowitz, Alok Singh

"Molecular self-assembly of phospholipids and other amphipathic molecules offers a versatile approach to form self-organized microstructures in various morphologies. Stabilization of microstructures in specific morphologies by polymerization renders them useful for practical applications in areas ranging from controlled release technology to template mediated synthesis of metals. Our efforts are focussed on the development of polymerizable biomembranes derived from phospholipids, their properties and utility e.g., as stable templates for studying chemistry at the lipid interface. Polymerized vesicles formed from mixtures of 1,2-bis(tricosa-1 O,12-diynoyl)-sn-glycero-3-phosphocholine, 1, with corresponding lipids having phosphohydroxyethanol,2, or -hydroxypropanol,3, headgroups have been used in electroless metal plating of vesicle surface with gold utilizing selective binding of Pd(NH3)4 2 + to 2 or 3. The surface bound palladium ion served as catalyst for metalization. Metalization of polymerized vesicles constructed from charge neutral diacetylenic phosphocholine,1, did not occur using this process. The headgroup structure of the negatively charged phospholipids and the degree of vesicle polymerization had an effect on the stability of the vesicles after metalization. Vesicles formed from a mixture of 1 with polymerizable diacetylenic phosphatidic acid, nonpolymerizable 1,2- dipalmitoyl phosphohydroxyethanol or 1,2-diacyl phosphohydroxyethanol (from soy lecithin) were not stable to metalization process. The metal coating of the vesicles was examined by electron diffraction and revealed that the gold metal on vesicles was polycrystalline and face centered cubic. The results demonstrate the utility of polymerized synthetic membranes as template for easy and efficient synthesis of nanoparticles. IntroductionPhospholipids, synthetic or natural, provide a simple and straight forward route to construct membranes in a variety of morphologies due to their inherent property of selforganization in the presence of water[1]. Vesicles are closed spherical structures comprised of concentric walls made from lipid bilayers. Vesicles are morphologically simple structures with enormous technological potential. Polymerizable phospholipids prepared by incorporating a polymerizable group in the molecules demonstrate physical properties comparable to their non-polymerizable counterparts and have the added virtue of providing enhanced physical and chemical stability to the membranes[2,3]. The size, shape and properties of the organized assemblies are dependent on the lipid structure and the nature of the aqueous environment[4,5]. The headgroup geometry, surface charge density, and spatial arrangement of the phospholipids are known to affect the surface behavior of the lipid membranes, which is evident through their interaction with other molecular (hormones, antigens, antibodies etc) or lomc species. Since phospholipid headgroup structure and charge can be modified either synthetically or by chemical perturbation of the aqueous medium (e.g., pH or ionic strength), phospholipid membrane surfaces offer a potential for developing novel strategies in those areas which involve the use of molecular reactive sites. One such strategy which could be envisioned explores the use of molecularly engineered phospholipid assemblies to design and prepare template structures to regulate formation of ordered materials [6]."

Jan 1, 1994

By L. Yuan, A. Smith

"NIOSH’s mine fire simulation program, MFIRE, is widely accepted as a standard for assessing and predicting the impact of a fire on the mine ventilation system and the spread of fire contaminants in coal and metal/nonmetal mines, which has been used by U.S. and international companies to simulate fires for planning and response purposes. MFIRE is a dynamic, transient-state, mine ventilation network simulation program that performs normal planning calculations. It can also be used to analyze ventilation networks under thermal and mechanical influence such as changes in ventilation parameters, external influences such as changes in temperature, and internal influences such as a fire. The program output can be used to analyze the effects of these influences on the ventilation system. Since its original development by Michigan Technological University for the Bureau of Mines in the 1970s, several updates have been released over the years. In 2012, NIOSH completed a major redesign and restructuring of the program with the release of MFIRE 3.0. MFIRE’s outdated FORTRAN programming language was replaced with an object-oriented C++ language and packaged into a dynamic link library (DLL). However, the MFIRE 3.0 release made no attempt to change or improve the fire modeling algorithms inherited from its previous version, MFIRE 2.20. This paper reports on improvements that have been made to the fire modeling capabilities of MFIRE 3.0 since its release. These improvements include the addition of fire source models of the t-squared fire and heat release rate curve data file, the addition of a moving fire source for conveyor belt fire simulations, improvement of the fire location algorithm, and the identification and prediction of smoke rollback phenomena. All the improvements discussed in this paper will be termed as MFIRE 3.1 and released by NIOSH in the near future INTRODUCTION The MFIRE program, originally developed in the 1970s by the U.S. Bureau of Mines (now the Office of Mine Safety and Health Research (OMSHR) at the National Institute for Occupational Safety and Health (NIOSH)) and Michigan Technological University, has been a mainstay in modeling of the mutual influences between a fire and the mine ventilation system during an underground mine fire. Several update versions have been released over the years, including MFIRE 1.27, 1.29, 1.30, 2.0/2.01, 2.10, and 2.20. The MFIRE program logically comprises four parts: (1) a conventional network calculation, where it performs the basic network balancing without considering heat or mass transfer; (2) a temperature calculation to establish the reference temperature distribution before a non-steady state (transient-state) simulation; (3) a transient-state simulation that follows changes in ventilation step-by-step to produce a continuous description of the temperature distribution, smoke, and contaminant spread through the ventilation system during a fire event; and (4) a quasi-equilibrium simulation to predict the state of the ventilation system after a relatively long period of time (defaulted as 5 hours in MFIRE) as the fire reaches a quasi-steady state. In summary, MFIRE is a computer simulation program that performs normal ventilation network planning calculations and dynamic transient-state simulation of ventilation networks under a variety of conditions including the influence of natural ventilation, fans, fires, or any combination of these (Chang et al., 1990)."

Jan 1, 2016

By J. V. Ghelarducci, M. A. Sharpe, D. G. Chedgy

This article presents a novel design, called the Climax, High Capacity Processor (HCP), for pre-combustion cleaning of coal. This design is particularly suitable for the plant capacities of 400 ~ 660 TPH. The HCP is different from the conventional designs with an equivalent throughput in three major aspects: 1) the use of one large capacity HM cyclone to separate coarse and intermediate raw coal in a single circuit; 2) the elimination of the conventional secondary magnetics recovery system by use of the high efficiency Climax, magnetic separators; 3) the use of "single line" piping with a minimum requirement of ancillary devices. In comparison with conventional designs with similar capacity, the HCP plant costs much less in capital investment, operation and maintenance.

Feb 24, 1997

By M. Kalin

"Ecological Engineering and Biological Polishing technology is a decommissioning approach for inactive coal, uranium and base metal operations. To improve acid mine drainage water some fundamental aspects of wetland ecology and sediment microbiology are combined, to provide conditions to allow for biomineralization of the contaminants.This paper summarizes the first records of microbial alkalinity generation in acid mine drainage through the utilisation of the ARUM process. The process requires that the seepage is at pH 4.5 where sulphate reducers utilize sulphate to produce hydrogen sulphide, which in turn precipitates with metals. The pH increase is brought about by alkalinity generating microbes.The ARUM process has been successful in increasing the pH from 2.5 to 7.0. Flow through reactors operated in the laboratory continuously for more than 60 days have removed Ni from 13 mg/L to < 0.01 mg/L. Design parameters are being developed for low flow rates of 5 L/min in a test system receiving seepage from a tailings.1.0 INTRODUCTIONAcid mine drainage associated with mining wastes poses a significant environmental problem. Conventional means to treat acid mine drainage (AMD) use chemical treatment system. Ecological Engineering technology uses natural biological means to curtail and ameliorate AMD during mine operations and at the time of decommissioning. The premise underlying Ecological Engineering technology is that AMD is the result of a natural process enhanced by mining activities. Therefore, in nature, a process providing a natural balance to AMD has to exist, which, when assisted through appropriate means, can counteract the detrimental effects of AMD on the environment. This process is microbial alkalinity generation which is known to occur in wetlands, lake and ocean sediments (Baas Becling et al, 1960)."

Jan 1, 1991

By Dale Preece, Stephen Chung, Qian Liu

Stoping is one of the widely adapted methods in underground mining. In this method, fanned or parallel holes are often drilled from a top sill down to a sub- level in the ore zone and blasted ring by ring into a stope for excavation. At Brunswick Mine of Canada, this technique has been used daily in conducting production blasts. However, when mining into the West Ore Zone, it has been identified strategically that a mass stope blast, involving the blasting of rock from the 3-sub level down to the 1-sub level, should be considered to ensure the safe operation and regaining of access to the trapped main ore zone. The challenge of this mass blast lies in the control of ground vibration and precise timing for blasting 800 holes drilled in six blocks from three different levels within 6.5 seconds, to allow sufficient void to be created in each level for the muck moving in order from the upper to the lower levels without bridging. This paper describes stope blast simulations using a discrete element computer code for modeling blast-induced rock displacement in conjunction with a precision electronic programmable delay timing system for various stope geometries including a drop raise blast at the start of the mass blast. The modeling concept is also described in the paper.

Jan 1, 2003

By N. J. Grant, B. C. Giessen, U. Wolff

With the aid of the splat-cooling technique of rapid quenching, metastable alloy phases based on antimony ad bismuth have been prepared. At room temperature, simple cubic phases were found in the Sb + Au, 56 + Yd, and Sb + Ni systems. Another phase was retained in the Au-Bi system at -190°C; in this systent, a microcrystalline phase and a rhombohedrally distorted phase were also observed. The crystal chemistry of these phases is discussed in terms of their valence electron concentration range. A remarkable five-step Phase sequence was found upon heating and equilibration of certain metastable Au-Bi alloys. USING the splat- cooling technique of rapid quenching from the liquid,&apos; a large number of metastable intermediate alloy phases have been prepared in recent years. Thus, Hume-Rothery phases of the hexagonal type based on the valence electron concentration have been produced in systems where they are missing in equilibrium, e.g., Ag-Ge 1 or AU-Sb. 3 In a comprehensive study of metastable alloys based on tin, simple hexagonal metastable y phases were found, raising the total of stable and metastable y phases from 3 to 13. 4 In the In-Bi system, five new metastable intermediate phases were retained.&apos; In most cases, the new metastable phases have some crystal chemical characteristics in common: a) They have rather simple, elementlike structures with few atoms per unit cell, e.g., y phase,4&apos;5 or the metastable primitive cubic phases in the Ag-Te and and Au-Te systems.= b) Their structures are often related to those of the terminal phases, or to elements that are straddled in their position in the periodic table by the constituent elements; this is the case for metastable ß (In-Bi) with the structure of white ß Sn,&apos; or metastable a (Cd-sn). 4 c) They seem to represent the crystal structures appropriate to certain average group number (AGN) ranges in which no or few single-phase structures exist in equilibrium. These average group number ranges can probably be equated in the case of many elements of the Ba(Zn)-Bs(As) groups with the averaged valence electron concentration. In the present work, the splat-cooling technique has been applied to the alloys of antimony and bismuth. In equilibrium, neither element forms intermediate alloy phases with other B elements from groups Bl(Cu) to B4(Si) that contain more than 66.7 at. pct of Sb or Bi, respectively, e.g., AUSb 2. 7 Thus, antimony- or bismuth-rich phases, which might be closely related to antimony or bismuth, and which would reflect struc- tural changes occurring on alloying with small amounts of addition elements, do not exist. Also, the terminal solubility of antimony and bismuth for all B metals is very small. It was therefore of interest to investigate the influence of enforced, nonequilibrium solid solution of addition elements in antimony and bismuth on their crystal structures. It was found that additions of group B 2-B4 metals act distinctly differently than additions of group T 10 and B1 metals. The latter set of additives will be treated here. EXPERIMENTAL TECHNIQUES Alloy preparation and splat-quenching followed closely the procedures described in Refs. 1, 4, and 5; they consisted of the preparation of master alloys from high-purity starting materials (99.99+ pct) and blast-atomizing of 20-mg quantities onto copper sheets. The resulting approximately 1 to 5 u thick foils were investigated by X-ray diffraction. The cooling rates obtained are of the order of 107 to 10 8 C per set,&apos;" causing solidification to proceed at a rat; of approximately 100 cm per sec.&apos; Powder patterns of the resulting fine-crystalline materials were taken with filtered CuK, radiation. For antimony alloys the substrates were held at room temperature and for bismuth alloys at -190°C both during splat foil deposition and X-ray investigation. Annealing treatments at several

Jan 1, 1969

By K. Rainer Massarsch, Bengt H. Fellenius

"Abstract Vibrations generated during the driving of piles or sheet piles can affect buildings or installations in the ground. However, observed building damage is not always caused directly by dynamic effects, but can also be related to foundation conditions. The importance of geotechnical conditions is usually not taken into consideration in most vibration standards. This paper describes how building foundations, and in particular mixed foundation types, are especially sensitive to ground vibrations. A method is presented for assessing the risk of settlement due to vibrations in granular soils. Also, a simple concept is proposed for estimating settlements in the vicinity of driven piles.1. INTRODUCTIONUnder unfavorable conditions, the installation of piles or sheet piles can cause damage to buildings or other structures on the ground. Frequently, such damage is attributed to vibrations of the building itself. In many countries, national or international standards are used to assess the risk of vibration damage to buildings. As such standards are often prepared by engineers with little or no geotechnical knowledge, the effects of ground conditions on vibration propagation and damage to building foundations are generally not recognized, and damage criteria based solely on the dynamic response of buildings neglect the importance of damage mechanisms governed by geotechnical conditions. One potentially important damage mechanism is differential settlement below buildings, especially when these are founded on loose granular soils. When seeking guidance in the literature, little or no information can be found regarding methods to assess permissible levels of ground vibrations with respect to risk for settlement.This paper focuses on building damage that can be attributed to foundation conditions. In the case of ground vibrations due to pile and sheet pile driving, differential settlements are of particular importance as the ground vibrations attenuate relatively rapidly from the source. Consequently, settlement below part of the building, which is located close to the vibration source, can be significantly larger than at a distance further away.Piles are often a cost-effective foundation solution for buildings on loose and compressible soil, frequently located in urbanized areas. Sheet piles are commonly used as support for deep excavations. While impact driving is most commonly used to install piles, vibrators are frequently used for driving (and extraction) of sheet piles. It is important to recognize the fundamental differences between impact and vibratory driving. During impact driving, the pile is subjected to stress waves of short duration. The driving process creates vibrations, which radiate from the shaft and/or the toe of the pile into the soil. The larger the intensity of the stress wave, the larger the dynamic force and the intensity of ground vibrations. In addition to the vibration intensity, which often is expressed in terms of particle velocity, also the vibration frequency is important. When the dominant frequencies of the generated vibrations harmonize with the resonance frequency of buildings or building elements, the risk of building damage increases."

Jan 1, 2014

By Jacolien P. Wyethe

Zincor uses a Roast-Leach-Electrowinning circuit to process zinc sulphide concentrates. It also processes zinc oxide fume, originating from a slag smelting operation in the Democratic Republic of the Congo (DRC). Zincor achieved an average zinc recovery of 90.3% during the period January 2006 to May 2007. The bulk of the losses occurred in the iron and lead silver residues, both as soluble and un-dissolved losses. The un-dissolved losses in the iron residue constituted around 33% of the total zinc lost from the circuit, and were largely attributed to the presence of zinc-ferrite in the calcine used for neutralization during iron removal. As part of Zincor?s continuous improvement programme, the un-dissolved zinc losses in the iron residue were targeted by: the partial replacement of calcine with zinc oxide fume (from the DRC); and the preferential use of ?low-ferrite content calcine? as neutralizing agents in the iron removal circuit. These initiatives, coupled with other operational factors, resulted in a marked improvement in recovery to 92.6% during June to December 2007. The zinc oxide fume, directly fed to the circuit, required investigation of the halide rejection capacity of the Zincor circuit. Rejection of chloride via the magnesium bleed operation was considered adequate. Fluoride was mainly rejected via the iron (~70%) and lead silver (~27%) residues. Fluoride rejection via the lead silver residue varied significantly, probably as a result of variations in the sparingly soluble CaF2 content in the feed. The mechanism for fluoride rejection in the iron residues is uncertain. The fluoride rejection capacity of the Zincor iron residue (comprising of mainly jarosites, schwertmannite and ferrihydrite) at 2 ? 4 mg/L F in solution, was estimated at 0.14 ? 0.19 kgF/tFe residue.

Jan 1, 2008

By Waldemar Lindgeen

PART I.—General Features. PAGE Purpose and Extent of Inquiry ; Definitions (Fissure-Veins, Metamorphism, Metasomatism, Impregnation, Cementation, Weathering); Metasomatism in Connection with Mineral Deposits, Especially Fissure-Veins; Calcu lation of Analyses ; Criteria of Metasomatism; Crystallization of Sec ondary Minerals in Other Bodies; Secondary Alteration of Veins; Structure and Composition of Metasomatic Vein-Rocks and Their Rela tion to General Metamorphism,.759 PART 11.—Minerals Developed by Metasomatic Processes in Fissure-Veins. Quartz, including Chalcedonite and Opal; Rutile and Anatase; Fluorite; Calcite ; Magnesite and Dolomite ; Siderite; Muscovite and Sericite ; Biotite; Chlorite; Pyroxene and A mphibole; Garnet; Epidote ; Ortho clase ; Albite ; Tourmaline ; Topaz ; Kaolinite ; Zeolites ; Pyrite ; Mar casite ; Chalcopyrite ; Arsenopyrite; Pyrrhotite ; Galena; Zinc-blende and Other Sulphides; Tellurides; Native Copper ; Gold and Silver,. 601 Resistant Minerals,........... 619 PART III.—The Fissure-Veins Classified According to Metasomatic Processes. 1. Topaz-Cassiterite Veins (Altenberg and Zinnwald, Saxony ; Mt. Bischoff, Tasmania),..........620 2. Scapolite-Apatite Veins,.........625 3. Tourmalinic Gold-Copper Veins,.. 626 4. Biotitic Gold-Copper Veins,........ 641 5. Propylitic Gold and Silver Veins (General Features; Comstock Lode; The Veins of Nagyág, Hungary; Pachuca, Mexico ; New Zealand; Alaska ; Silver Cliff, Colorado; Silver City, Idaho),. .. .645 6. Fluoritic Gold-Tellurium Veins (Cripple Creek ; Other Occurrences),. 654 7. Sericitic and Kaolinitic Gold- and Silver-Veins (General Remarks; The Freiberg Veins ; De Lamar, Idaho; Summit District, Colorado),. . 6.58 8. Sericitic and Calcitic Gold-Silver Veins (The Gold-Quartz Veins of Cali fornia ; Idaho Types ; San Juan, Colorado ; Treadwell Mine, Alaska ; Gold Veins of Ontario, Canada; Schwarzwald Fissure-Veins),. . 664

Jan 1, 1901

A study was undertaken to investigate the relationship between the quantity and value of economic demonstrated resources discovered for 12 mineral commodities over a ten year period and the expenditure required to yield such mineable resources. The results showed that for every dollar spent on exploration, there is an apparent in-ground average value of around $54 dollars contained in the economic resources found. While this appears to be a satisfactory return, it should be remembered that more than 99.9% of exploration programs are judged to be failures because a viable ore body or mineral deposit was not proved up. What is behind this seeming paradox? &nbsp; The fundamental truth behind mineral exploration is the fact that the more you explore, the more you find, and that one success will often lead to further discoveries. It appears that one rich and viable deposit creates such surplus that its inherent high value (&apos;the pot of gold&apos;) makes up for all the failures. In short, mineral exploration is a high risk business with uncertain returns. However, with skill, enthusiasm, experience and venture capital, it can yield larger than normal returns for the brave and the fortunate. &nbsp; Analysis of exploration expenditure and economic resources discovered for the period 1987 to 1996 revealed that the apparent in-ground value of economic ore discovered per dollar of exploration expenditure varied from a high of $429 for iron ore and $261 for bauxite to a low of $22 for gold and for lead, and $5 per dollar of diamond exploration expenditure. Preliminary conclusions drawn on the reasons for the variations observed include the inherent ease or difficulty of discovery for different mineral commodities which may in some cases, relate to the natural prospectivity of Australia as a whole. Layered deposits like iron ore and bauxite appear to yield higher in-ground value returns on the exploration dollar. To some explorationists, this may be considered as seemingly obvious, but it may have more to do with very large-exploration tenement grants pursued by various Australian State Governments in the early 1950s and 1960s than the apparent ease of delineating a stratabound deposit. &nbsp; Despite the apparent relatively low in-ground value produced by the gold exploration dollar of $22, the 5660 tonnes of gold discovered in this ten year period was worth $9.1 billion and representing over a quarter of the new mineral wealth created in the ten years to 1996. This contribution, along with that from the other minerals discovered over the period, led to a significant boost to Australia&apos;s export income and standard of living. &nbsp; It is concluded that, given the nexus between the amount of mineral exploration expenditure and the quantity of new resources likely to be discovered, this knowledge may help policy makers seek to influence the rate of resource discovery in countries like Australia for the benefit of the nation.

Jan 1, 2004

By J. F. Haseman, J. E. Davenport

IN the brown rock phosphate fields of Tennessee there are large deposits of phosphate matrix in which quartz is a major constituent of the gangue, and which cannot be beneficiated by the conventional washing process to yield a concentrate of suitable grade for use in the electric furnace. A huge tonnage of high-grade phosphate concentrate is produced in the Florida pebble district from low-grade siliceous feed. However, the characteristics of the low-grade siliceous Tennessee ore are such that flotation under the conditions employed in treating the Florida ore1-2 results in inadequate beneficiation. INVESTIGATION OF FLOTATION METHODS Flotation has been used in Tennessee primarily to produce a concentrate of premium grade by moderate enrichment of a marketable grade of phosphate.3,4 A secondary use was to increase the recovery of phosphate from the fines (down to approximately 200 mesh) from medium-grade ores with a concomitant moderate increase in over-all grade.3,5 It was considered desirable to investigate methods of improving the grade of washed products from low-grade siliceous Tennessee ore when these products were substantially below the requirements for use in the electric furnace. The present paper describes the results of a laboratory-scale study of factors that affect the beneficiation of such siliceous phosphate ore by flotation. The primary objective of the investigation was to ascertain the conditions under which the ore could be made to yield a concentrate suitable for reduction in the electric furnace. It was assumed that a phosphate concentrate for electrothermal reduction should contain at least 26 pct P205 and should have a weight ratio of silica to lime of not more than 0.80. Since a concentrate of moderate grade can be used in the electric furnace, and since, as Grissom4 has shown in detail, the ore will not bear the cost of expensive treatment, the study of collectors was limited to the relatively inexpensive fatty acids. A secondary objective was to determine whether a portion of the phosphate could be recovered in a grade suitable for treatment with phosphoric acid to produce 45 pct superphosphate. The ore consisted of variably cemented sand interlayered with clay. The sand layers were composed of grains of quartz, phosphate, and clay embedded in a matrix of clay and phosphate. Some clay was finely disseminated in the phosphate grains. Little massive high-grade phosphate was present. The material used in the flotation tests was a washed sand that had been separated from the ore in a bowl classifier at the TVA phosphate-washing plant. The percentage composition of the sand was as follows: P205, 20; Si02, 40; CaO, 29; Fe203, 2; A1203, 3; F, 2.3. The particle-

Jan 1, 1947

By H. N. Lawrie

This study was undertaken on account of the lack of definite knowledge concerning the influence of bismuth on wire-bar copper, and the small elimination of bismuth from copper-matte during the smelting-operations. The early workers who studied the influence of bismuth on copper confined their investigations to malleability and ductility—two physical properties which are related to the others so intimately that their determination is of primary importance. Karsten and Levo1,² using bending- and mealleability-tests, seem to have been the first to take up the subject, and while their results are incomplete, they agree in the main with the later work of Hampe.3 The bending-tests used by the first investigators consisted in bending the specimen until it failed. The malleability-tests were made by beating the material to a knife-edge with a hammer. Hampe not only determined the percentage of bismuth which would cause red-shortness and cold-shortness of the alloy, together with other influences of bismuth on the malleability and ductility of copper, but also took up the influence of the bismuth protoxide, BiO, on copper, and of bismuth sesquioxide, Bi,O,, on the copper protoxide, CuO. Hampe&apos;s conclusioris of the influences of these two latter compounds of bismuth on copper are as follows : "If the protoxide of bismnth be alloyed with metallic copper, it is not changed to metallic bismuth, but remains mechanically distributed throughout the copper.

Jan 1, 1910