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By D. Kovachevich, M. A. Pfeifer

"A t remote locations typical of mines and associated ore processing plants, diesel electric generators are ideally suited for power plants due to their inherent operating flexibility, efficiency and reliability. In recent years rapid escalation in fuel and related transportation costs has made extensive waste heat recovery from generating sets financially attractive to a much greater extent than previously.The paper outlines key considerations during planning and design stages for utilizing the various waste heat sources available to best advantage. Based on two /980 mining projects built in the Canadian Arctic, data is presented on potential operating and capital costs savings. A review of heat balances, engineering flow diagrams and major equipment selections for process and building heating systems utilizing waste heat is included.IntroductionResource projects increasingly occur in remote areas requiring on-site self sufficiency in electrical power generation. For such projects, the low- or medium-speed turbo-charged diesel engine is very often the preferred choice as a prime mover for the generating sets . It is inherently reliable, has good response to load changes and has comparatively high fuel efficiency over a wide load range . From a project execution standpoint, It is capital cost- competitive and procurement lead-time normally ' fits ' within tight schedule constraints. In addition, its potential for waste heat recovery is excellent , particularly in northern climates where space heating requirements are usually substantial, and also where there a re requirements for heat for process and plant services.The high cost of fuel , with add-on transportation costs , provides a major incentive to fully exploit the available waste heat recovery potential o f such installations.As a result of the rapid escalation in the price of petroleum products following major crude oil price increases in 1973 and again in 1978-79, liquid petroleum fuels, having the desirable properties of comparatively high heat content and transportability, are no longer 'cheap' commodities and have become so valuable that industry has widely undertaken serious conservation efforts.Currently, it appears that petroleum cost trends of the 1970s may not continue, at least in the near term, and that we may see somewhat reduced energy costs for a time. In the longer term , and certainly within the life spa n of major projects, however, it is generally believed to be inevitable that these fuels will be increasingly expensive . Energy costs are today a major operating cost for remote minerals processing plants and will remain so for the foreseeable future.In order to meet the economic challenge posed by high energy costs, future projects should be thoughtfully planned from the outset with the goal of minimizing energy requirements and maximizing the use of waste heat recovery to meet such requirements. There is also considerable potential for significant energy savings by retrofitting of existing installations."

Jan 1, 1984

By X. Y. Liu

A culture-independent approach based on 16S rRNA gene clone library was used to analyze the bacterial community change both associated to the solids and in the liquid phase during pyrite bioleaching process. Phylogenetic analyses of 16S rRNA fragments revealed that the retrieved se-quences mainly related to genus Leptospirillum, genus Sulfobacillus and genus Acidithiobacillus. During the bioleaching process, genus Leptospirillum trends to grow associated to the solids while major of genus Sulfobacillus were in the liquid fase, only accounting little portion in the solids. Genus Acidithiobacillus can grow both on the solids and in the liquid phase, but accounting high portion on the solids.

Jan 1, 2014

By Kenichi Fujino

Severe disasters have struck Japan in recent years. Following these disasters, construction robots have played important roles in investigation and restoration work in the disaster regions. To be applied in this way, construction robots require many functions according to the purpose of their use in each case. There are clear differences in the functions and usage conditions required by investigation robots and those required by execution robots. These differences will be important when designing and operating construction robots in the future. This report introduces a volcano exploration robot and unmanned execution system as examples of construction robots used for investigations and executions respectively. Based on this, the report organizes important characteristics of construction robots and explains differences in the concepts of disaster investigation robots and disaster restoration robots. Because they are used in harsh natural conditions and do not have any execution functions, efforts are made to clarify the fact that investigation robots have to overcome many problems such as mobility. When a construction robot is used, the scenario of the operation of the construction robot (execution plan) is extremely important, and in addition, it is necessary to clearly define the way it will be used according to the purpose of its use and specification conditions. In a plan for an unmanned execution system, it is possible to mitigate several strict prerequisite conditions by proposing a well-constructed execution plan. For example, the execution efficiency of an unmanned execution system can be improved by effectively using a temporary road.

Aug 1, 2013

By C Fountain

Australian mining and engineering companies have increasingly been investing in the mining industry in Brazil. It is a country of enormous mineral and agricultural wealth, with a well-established mining sector. Some Brazilian mining companies and personnel have been journeying in the opposite direction. There are significant differences in the approaches to engineering between the Australian and Brazilian industries that can cause confusion for companies operating in the other country. These range from differing expectations during the various stages of feasibility studies to style of plant and contracting strategies during the construction phase of projects. Some of the differences are driven by tax regimes, labour costs, or different settlement patterns. Others are the result of different histories and pressures on the industries in the two nations.This paper describes some of the differences in approach found in the two countries and some of the reasons for them.

Aug 8, 2011

By M. Save, N. Menad

"This paper gives the overview of different alternatives to recycle the following wastes: slag, dusts, wastes of electric and electronic equipment (WEEE) and auto shredder residues (ASR). Based on modified Bogue calculations, steelmaking slags were combined in order to produce a belite-rich clinker activated with sulphoaluminate. The EAF dusts containing significant amount of metals can be recycled in different ways: The carbothermal treatment and INTECT process are reported. The results obtained from the model of Auto Shredder Residue injection into blast furnace show that ASR can be used as reducing agent in the BF process if certain conditions are met. The particle size of this material must be controlled to ensure optimal gasification of the material in raceway. The non-ferrous contents may affect the pig iron quality, which is difficult to rectify at a later point. It seems the pyrolysis is the most attractive process to handle ASR. The BRGM flow sheet of WEEE treatment is also reported.I. Introduction The activities of human been may generate wastes and by their accumulation during several years, these wastes may have an impact on the environment and on the human health. These wastes can be generated in the forms of solid, liquid and gas. A variety of industrial wastes can be recycled for use as products. There are three ways in which industrial waste recycling occurs: at the facility itself (on-site recycling), at commercial facilities that gather waste streams from several companies (off-site recycling), and at a company that uses as inputs in its production process the waste products of another company. The industries producing iron and steel may generate different solid wastes which are classified in three main categories: 1. Ferrous material (mainly dusts and sludges from gas cleaning), 2. Slags (these by-products are generated from different process stages), 3. Others by-products (including refractories and material generated from engineering activities). According to this review, the most quantity of the metallurgical wastes is deposed. Currently, the public opinion opposes the creation of new sites. This leads to the growth of the waste disposal costs. Such situation reduces the enterprise competitiveness and decreases their market share on regional and/or national and/or world scales. In these conditions, the economical activities can be decreased leading probably to social problems. The problem of wastes and/or by-products can be treated on three levels:"

Jan 1, 2008

By Michael Arnold, Jonathan Delgado

In 2017, Bauer Foundation Corp. (BFC) was awarded the contract to install the deep foundations for the new 17-story Hotel Tower and the Low Rise Casino Expansion at the Seminole Hard Rock Hotel and Casino in Tampa, Florida. The site was underlain by extremely challenging Florida Limestone geology and surrounded by occupied existing buildings and infrastructure. To overcome the challenges of the difficult subsurface conditions, and to successfully complete the foundation installation without impact to the surrounding buildings and casino operation, Langan Engineering (EOR) and BFC were required to modify both the design and installation techniques during construction. The scope of work included 147 temporarily cased drilled shafts to depths up to 230 ft (70 m) below ground surface (BGS), 76 permanently cased micropiles up to 200 ft (61 m) BGS, and more than 300 augered-cast-in-place (ACIP) piles up to 125 ft (38 m) BGS. Voids and zones of high permeability in the limestone created many challenges for execution of the foundation scope including ACIP piles overbreaks of more than 400% above neatline volume, and construction induced ground subsidence/collapses adjacent to structures supported on shallow foundations. This paper will discuss site limitations, design and construction challenges, difficult geology, varied soil conditions, and lessons learned. PROJECT The project is located at Seminole Hard Rock Hotel and Casino Tampa, Florida, as shown in Fig. 1. Seminole Tribe, the owner, started the construction of a new 17-story Hotel Tower and the Low-Rise Casino Expansion at the beginning of 2017.

Jan 1, 2018

By J. Wiebmer

Some thoroughbred racehorses are great routers (distance runners), others are sprinters. Some racehorses perform best on turf, others on dirt, and some in mud. To be a winner, you have to choose the right horse for the course. It's no different when looking at an electric cable shovel, a hydraulic shovel/excavator, or a wheel loader. Each loading tool has its own zone of application. To be a winner, you have to choose the right horse for your course.

Jan 1, 1993

Amongst representative men directing alluvial mining of erations in Victoria, some difference of opinion exists as to the best system of working the deep leads. The developmental operations of shaft-sinding, extending a reef drive, partially watering and rising up into the wash dirt are practically the same on all fields but subsequent mining is continued either on the Chiltern and Rulberglen or Ballarat systems, the latter being referred to by the Chiltern and Rutherglen miners as the "down country" system. In the former, the leading wash and cross drives are lept from 300 to 500 feet ahead of the reef drive, and in the latter the reverse method keeping the reef drive well ahead of all wash workingsis adopted.In the majority of alluvial mines in the southern and western fields, the initial work of defining the course of the lead is costly, owing to the thick superincumbent layers of hard basalt, to bore which costs from 9/- to 15/· per foot. Unfortunately large sums of money have been wasted in this work, owing to a want of care and knowledge in the selection of bore sites, and improper recording of the strata pierced, thus handicapping alluvial mining and bringing boring operations...

Jan 1, 1902

By M. V. K. Reddy

A differential flotation process for recovery of molybdenite from chalcopyrite concentrates produced at Rakha Copper Concentrator, Bihar, India has been developed. The flowsheet is simple, and relatively inexpensive and yields a concentrate assaying not less than 45% Mo at a recovery of minimum 65%, starting from chalcopyrite concentrate assaying 0.4% Mo. The consumption of the main depressant used, sodium sulphide is not more than 25 kg/t of copper concentrate processed without steaming; and with steaming the consumption was brought dorm to less than 12 kg/t of concentrate. Further reduction is possible by optimization of steaming parameters. Based on laboratory experimental results, further tests were conducted on concentrator site and process design parameters were established for design of commercial plant.

Jan 1, 1982

By James J. Tansey

A Deep Foundations Institute meeting with the University of Michigan at Ann Arbor in March of 1984 featured legal rights under Differing Site Conditions. A workshop conducted by the authors and Gerard Ittig, Esq. added to the value of the symposium. This paper will be of interest to your attorneys in any subsurface disputes.

Jan 1, 1985

By Jürg Künzle

Underground construction is a matter of dealing with the inherent uncertainty of subsurface geology. If the encountered conditions are less favorable than the expected ones, the execution of excavation, support, ground treatment or lining works is likely to require more or different efforts than anticipated, thereby delaying the works and increasing the costs. The 2019 first edition of the FIDIC Emerald Book model contract (FEB) addresses many of the issues to which underground works give rise, including those related to differing site conditions (DSC). This paper examines how under the FEB disputes arising from or in connection with DSC could or should be avoided.

Jun 13, 2021

By Peter J. Tarkoy

The use of personal computers (PCs) is increasing in underground construction applications, specifically, for estimating, record keeping, construction performance analysis, project cost reporting, and the effective application of construction experience for estimating and aggressive bidding. Applications particularly suited to the PC are analyses of construction performance and differing site condition claims. The advantages of using a PC in the analysis of differing site conditions claims is that the PC: requires quantitative and factual data, allows vast data manipulations, calculations, and sorting, and provides a simple graphic representation of complex data and issues. The restrictions imposed by a PC are conducive to the focus on essential facts, issues, quantitative analyses, and inherently, the truth. As computer thinking is established, a clearer, more precise and accurate focus on the elements of a differing site condition is essential for successful evaluation and presentation.

Jan 1, 1987

By AIME AIME

AT a recent meeting of the Utah Section. A.I.M.E., P. D. Nielson, general plant superintendent of the new Geneva steel plant at Provo, Utah, spoke on "General Operations of the Geneva Plant." Mr. Nielson explained that the plant was located at Provo, Utah, on account of railroad facilities, the proximity of coal, iron, and limestone, and the nearness of water for operating the plant. Water probably was the most important item in making the decision.

Jan 1, 1944

By Orlando Oliveros

The Los Bronces Mine and Concentrator, one of the three operating units of Compania Minera Disputada de Las Condes S.A. (an Exxon Minerals Co. affiliate), is located in the high Andes of East-Central Chile approximately 70 kilometers northeast of Santiago at an elevation of 3,650 meters above sea level. (Figure 1). Santiago, the capital city of Chile, is located at an elevation of about 500 meters above sea level and enjoys a very mild climate, similar to some areas of California. At the mine site, however, extremely heavy winter conditions prevail occasionally, with very heavy snow and the resulting snow avalanches endangering installations and people. At the same time, ideal skiing conditions are found at the nearby ski resort of Portillo and Farellones. Mount Aconcagua, the highest mountain in the western hemisphere is only about 55 kilometers further to the northeast of the Los Bronces mine.

Jan 1, 1983

By Ronnie W. Sisk

1. Troubles start early - Inadequate Geotechnical Data A. Owners think they are saving money by allowing limited soil borings at their site. This places a high gamble on the bidders and the Lump Sum Price will be higher. B. Inaccurate elevations on soil reports. a. Surprises in depths - over or under design bid bottom elevations. 1. Requires backfill and extraction of casing that is too short for the greater depth of the drilled shaft. 2. Redrill utilizing longer casings. 3. Softer earth (backfill) can cause difficulties in redrilling such as less quantity extracted on the auger and maintaining plumbness. 4. Greater concrete overrun. b. Extreme under depths. 1. Excessive concrete is placed as a result of planning for a deeper shaft. c. Geotechnical report that does not supply a layout of boring locations. d. Design Engineer does not have a basic knowledge of how a caisson is installed.

Jan 1, 1988

By William A. Johnson

IT was pointed out in an earlier paper1 that our understanding of the atomic mechanism by which diffusion occurs in metallic alloys is scarcely in an advanced state. This unsatisfactory condition is the result not of any lack of interest, but of the difficulty of designing experiments that will yield suitable data. The diffusion coefficient of an alloy, measured in the usual way, is simply a number specifying the rate of homogenization of a nonhomogeneous metal; this number, of itself, can furnish neither the rate at which the individual atoms move nor information as to the mechanism by which they move. It does not necessarily follow, however, that such information cannot he obtained, even if the path to be followed is still not clear. Much success has been attained in the study of diffusion in ionic crystals. A number of experiments, for which there are few counterparts in connection with metals, yields information often indicating a detailed mechanism by which diffusion probably occurs. From such work, quite acceptable theories of lattice imperfections have been developed by Wagner, Schottky, Frenkel, Jost and others.2 It is postulated that real crystals of stoichiometric composition contain, in equilibrium, certain imperfections of which the most important types are: (I) vacant cation sites, with an equal number of interstitial ions; (2) vacant anion sites, with an equal number of interstitial ions; (3) equal numbers of anions and cations in interstitial positions; (4) equal numbers of vacant anion and cation sites. The classification of a particular crystal according to this scheme then follows from studies of the variation of electrical conductivity with pressure of the electronegative component surrounding the crystal, with ion size, and with temperature; other physical phenomena, such as the Hall effect, have aided in establishing the classification. The relative mobility of the anion and cation may be determined by chemical analysis of the salt at the electrodes following electrolysis. With such information, and knowing that one ion never occupies the lattice site normally belonging to an ion of opposite sign, it is usually possible to ascertain the diffusion mechanism. It is clear that the same experiments are not applicable to metal crystals, and substitute experiments that yield as much information have not yet been devised. Much can be learned, however, about the mobilities of the two* kinds of atoms in alloys by the use of radioactive metals as indicators. Only one such experiment has been performed in the past. In 1933, Seith and Keil,3 in an effort to explain the great difference between the rate of diffusion of gold in lead and of lead in lead, measured the rate of diffusion of radioactive lead in a gold-lead

Jan 1, 1942

By L. S. Darken

IT has been known for sometime that in an ionic lattice, such as that of Ag2S or FeO, the migration velocity of the anion may differ markedly from that of the cation, the cation being usually the more mobile. It has been shown, for example, that during the formation of silver sulfide tarnish on silver, the tarnish layer grows principally by the motion of silver cations through an essentially stationary silver sulfide lattice. Similarly, the growth of wüstite scale on iron proceeds principally by motion of iron ions, this being accomplished with the aid of vacant iron lattice sites into which the iron may readily move. Likewise investigations of solid solutions of various salts show that there is usually considerable difference in the mobility of the different cations. Measurements of the mobility of various metals in liquid mercury indicate that the various metals move at different rates relative to the mercury. In view of the foregoing it seems reasonable to suppose that when any single phase solution is acted upon by a field, the atoms of different elements respond in different ways; in particular, that the force arising from a particular concentration gradient in a binary alloy would cause the atoms of one component to move with a drift velocity which is in general different from that of the atoms of the other component. The recent experiments of Smigelskas and Kirkendall1 support this viewpoint, since they found, in essence, that during diffusion in alpha brass zinc moves appreciably faster than copper. This was evidenced by the relative motion of inert molybdenum wires. Such a phenomenon is incompatible with the place interchange theory of diffusion proposed by several authors, most recently by Birchenall and Mehl.2 This theory has, however, also been questioned3.4 for other reasons, principally because of the high energy required for direct atomic interchange. The rather large difference between self-diffusivity, as determined by tracer technique, and mutual diffusivity, as determined with the aid of another element at low concentration, might also be interpreted as favoring the above idea; however, Birchenall and Mehl have pointed out that there is another possible interpretation of this difference; this is discussed later. A rather interesting and pertinent observation was made by Schwartz,5 who noticed that tungsten lamp filaments, heated by direct current, commonly fail by necking down in the region at the temperature gradient near the positive end, with a concomitant swelling at the corresponding position near the negative end. He introduces considerable auxiliary evidence to show that this phenomenon is occasioned by the motion of tungsten cations which migrate in the high temperature region from the positive end toward the negative end. The mechanism of this migration is not clearly understood. If, however, this experimental evidence be accepted, we are forced to conclude that alloying elements in the tungsten may migrate by the same or a similar mechanism, whatever it may be, at a greater or lesser rate, thus giving rise

Jan 1, 1948

By N. K. Dumakor-Dupey, G. B. Sakyi-Addo, K. J. Bansah

"Artisanal and small-scale mining (ASM) occurs in many countries around the world, and provides a source of livelihood to many impoverished local people in areas where it occurs. This paper reports the role of female participants and reasons why they engage in ASM. Field visits were made to 12 ASM sites located in the Tarkwa Mining District of Ghana to conduct interviews with male diggers and female participants. It was observed that over 100 women between the ages of 18 and 50 participate in ASM for survival. They engage in ASM largely because they have no alternative employable skills and income sources. These female participants depend on ASM to sustain the lives of their dependents. INTRODUCTION Artisanal and small-scale mining (ASM) conventionally involves use of rudimentary tools (such as picks, shovels, chisels and hammers) to exploit precious minerals and metals from the ground. It has been a major source of livelihood to many impoverished local people for more than a century. In many instances, it is the only source of income to indigenous people who have no alternative employable skills. The World Bank estimated that more than 100 million people around the world benefit from ASM which largely occurs in developing countries in Asia, Africa, Oceania, and South and Central America (World Bank, 2013). Cobalt, which is used in lithium-ion batteries to power cellphones, laptop computers, and electric vehicles, is largely produced by artisanal miners in Congo (The Washington Post, 2016). In Sudan, ASM is a significant contributor to the national economy, accounting for about 85% of total gold extracted yearly from 2010 to 2015 (Ibrahim, 2015). Also, according to the Embassy of Sierra Leone in Washington DC, USA, 90% of mineral export in Sierra Leone can be attributed to thriving artisanal diamond mining in the country (Sierra Leone Embassy, 2016). In Ghana, the ASM sector was recognized by government as a multimillion industrial activity, and through a series of initiatives, it was legalized by promulgating the Small Scale Gold Mining Law of 1989 (PNDCL 218). Presently, artisanal mining is widely practiced in two forms: licensed (registered), sometimes referred to as formal ASM, and unregistered (informal or illegal) operations, popularly called “galamsey”, a name believed to have been derived from “gather and sell” by ancient miners who could not communicate in the English language with European/British miners. The ASM sector in Ghana, like other countries, has seen a rise in female participation over the years. A report by the International Labour Organization (ILO) indicated that women account for about 15% of total workforce in ASM in Ghana, and up to 50% in Africa (ILO, 1999). Other researchers have also estimated women participants in ASM to be between 30 and 70% in Africa (Hinton et al., 2003a; Hinton et al. 2003b; Hilson, 2002). Presently, there is no reliable data from Ghanaian authorities on number of females engaged in ASM. However, data obtained from 15 ASM sites suggest that at least 40% of the employees are women. It is expected that a similar trend exists across ASM operations in Ghana."

Jan 1, 2017

By Robert Bachus, Nikolaos Machairasm, Allen Cadden

Data Interchange for Geotechnical and Geoenvironmental Specialists (DIGGS) is a data transfer standard that is gaining widespread acceptance in the geotechnical and geoenvironmental communities. Originally developed using funding from the Federal Highway Administration (FHWA) to efficiently capture data related to geotechnical boring logs, cone penetration test (CPT) soundings, and lab testing results, the data transfer protocol is rapidly gaining traction. It has been shown to have beneficial impacts in other allied areas where disparate parties (i.e., consultants, contractors, vendors, etc.) routinely publish/submit data as part of project deliverables. The historic problem is that many of these submissions use paper copies (i.e., .pdf images) to transmit valuable data for the project… data that may extend beyond the “technical” aspects of the project (e.g., equipment operating conditions, construction production rates, project costs, etc.). These data could be used by multiple parties to assess project performance and safety, as well as to track productivity, etc. Currently, in the limited situations when actual data are compiled and transmitted, the data often are submitted as an author-specific (and often proprietary) software application and must then be re-entered into other software applications (e.g., analysis software, database, etc.) for use beyond simple data collection. An initiative undertaken by the Geo-Institute (G-I) of the American Society of Civil Engineers (ASCE) focuses on exploiting the full potential of DIGGS to geoprofessionals both within and outside of the transportation community. The deep foundations industry represents one community that could benefit significantly from using DIGGS. Data of interest to DFI members include production records, quality assurance information (e.g., verticality and alignment, concrete strength), and, importantly, load test results. When adopting DIGGS, users need not modify how they capture data, but rather will use DIGGS as a vehicle to transfer data to other applications in a standard format where it can be shared, used, stored, and retrieved. This paper and associated presentation will describe DIGGS and demonstrate how DIGGS can be used effectively within the deep foundations community.

Jan 1, 2019

By Scott White, Pishun Tantivangphaisal, Andrew Bell, Chris Barker

There has been considerable advancement in recent years in the tools, both software and hardware, available to allow efficient digitalization of site records during the construction of geotechnical works. Whilst these tools have excelled at replacing handwritten records, the ability to use digital records to validate design and construction requirements in real time or even within reasonable timescales has generally been limited to the development of bespoke ‘prototype’ project specific solutions. This paper describes the development and implementation of an industry standard design schedule and the benefits of the broad adoption of a single database schema for data recorded on geotechnical sites. The former has brought significant improvements and automation of the design process, whilst the latter has enabled the validation of the constructed works against design intent in almost real time. Further details of the standardized design schedule, already publicly available in the UK through the FPS, examples and lessons learnt from implementing digital site record systems on live projects are presented herein. The utilization of cloud computing technology and complex algorithms linking plant/rig instrumentation with design data can further automate construction sites using IoT (Internet of Things) best practices. The authors will share their experience of the recent deployment of a digitalized design-to-construction record system, give recommendations for future development and a call for an industry wide drive to finalize and adopt the AGS Piling data schema.

May 1, 2022