Search Documents

By Aubrey Mainza, Malcolm S. Powell

"A hydrocyclone with two vortex finders, named the three-product cyclone, has been successfully tested in the Platinum industry for dealing with the dense chromite found in UG2 ores. This dense component preferentially reports to the cyclone underflow, resulting in an over-ground fine chromite component in the final product. The dense media effect caused by a high chromite concentration in the cyclone feed produces a coarsening of the cyclone overflow, which results in loss of recovery through over-size material in the float feed. The fine barren particles of chromite that report to the overflow are recovered through entrainment in the flotation process, resulting in detrimental contamination of the slag produced from the concentrate.With the three-product cyclone a middlings product has been extracted that has a higher concentration of fine chromite. This volumetric stream flow represents a small percentage of the total cyclone feed and it is thus possible to treat it separately via fine screening to remove the fine chromite from the system and recover coarse silica."

Jan 1, 2003

By B N. Noller, J C. Ng, S L. Bruce

Mining activities can result in the transfer of harmful elements, including arsenic and lead, into the environment. In Australia, one of the potential future uses of rehabilitated mine land is to stock grazing animals. Elemental uptake is dependent on bioavailable fraction for adsorption upon exposure. Bioavailability data are generally lacking in order to provide realistic health risk assessments relating to harmful elements from mine tailings in Australian conditions. Another key component of risk assessment is the ability to estimate a realistic exposure, or dose rate, of the tailings to the grazing cattle over a set period of time. Hence, we aimed to conduct grazing trials directly on rehabilitated tailings facilities in order to provide valuable in situ information on heavy metal dose rates and associated accumulation. For the laboratory-based evaluation of comparative bioavailability, groups of cattle were fed five days a week on a normal diet spiked with mine tailings or soluble pure salts of target elements (eg sodium arsenate, sodium arsenite and lead acetate) for about eight months. For the field validation, cattle were allowed to graze directly on rehabilitated tailings facilities over a similar length of time. Blood and a biopsy of the muscle and liver were periodically collected to monitor arsenic accumulation. At necropsy, blood, muscle, liver, kidney and other saleable tissues were measured for arsenic concentrations. Although this study was focused on arsenic, lead and other metals were also measured. Predictive models for arsenic and other metals have been established to calculate the maximum grazing duration without the risk of exceeding specific food safety guidelines. The outcome of this study is a predictive model for maximum beneficial use of certain rehabilitated tailings for cattle grazing where grazing activities do not impact on the integrity of the tailings dams.CITATION:Ng, J C, Noller, B N and Bruce, S L, 2014. A predictive model for beneficial use of rehabilitated mine tailings for grazing cattle after mine closure, in Proceedings Life-of-Mine 2014 , pp 563–572 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 16, 2014

By Dirk Bergmann

During the spray forming process, a continuous molten metal stream is atomized by impinging high speed inert gas jets. In the generated spray cone, the resulting metal droplets are rapidly cooled by the huge temperature difference to the surrounding gas phase and thereby partly solidified during flight. After a certain flight and residence time inside the spray cone, the droplets impinge onto the solid substrate and form the product (deposit) by compaction. Material properties of this preform strongly depend on several process parameters and especially on the thermal and kinetic state of the deposited droplets at the point of impingement. Smaller droplets may cool very fast due to their low mass and impinge onto the product in a completely solidified state as solid metal powder particles. Larger droplets with big mass contain a higher amount of thermal energy and impact during the state of phase change or still as completely liquid. It is obvious, that a certain amount of liquid content in the droplets is needed for forming a homogeneous deposit. Therefore, the thermal history of metal droplets during flight in the spray cone is of great importance for overall process modelling and control. Modelling the effects of the impinging droplet mass on the formation and heat balance of the deposit, the thermal conditions of the droplet stream need to be temporary and spatially averaged at different locations. Averaging may be achieved in different ways, giving alternative results. A first method is averaging over the droplets total enthalpy which consists of the thermal content and the remaining latent heat of fusion within the droplets. A second method may yield the average over the heat content and the solid fraction separately. Results of these two methods depend on the application and the kind of information which one wants to achieve and show some deviations, which will be discussed in terms of consolidation and energy conservation of the deposit.

Jan 1, 1999

By T Burns, P Savory

In 2013, Rio Tinto Iron Ore (RTIO) produced 251 Mt from 15 mines in Western Australia. Throughout the mines, Ore Reserve models are used for long-term and medium-term mine planning. Grade control data aids the accuracy of short-term planning. Reconciliation of models with grade control data is important for maintaining confidence in predictions from the models, understanding the limitations of the models, and identifying issues that may require further work.There are a large number of sites and models, with more than 200 professionals involved in different parts of the reconciliation process. Regular meetings of all involved and enabling effective communication are important in the reconciliation process.Reconciliation data is gathered and processed through a web-based system; Grade Block Reconciliation System. This system cuts each grade block against the required model, stores the results, and allows users to view and analyse the data. Development of this system has occurred over a number of years and all Rio Tinto Iron Ore mine geologists and resource geologists now use it as standard to report reconciliation results. The results can be viewed in many ways including by different time periods or benches. Graphing the results assists identification of trends. Centralising and standardising reconciliation has allowed easier comparison between sites. Flexibility in the system allows users to customise reports to manage issues unique to their particular site.In parallel with system development, substantial effort has been put into ensuring mining professionals get together to discuss and understand reconciliation issues. To facilitate this there are now regular sessions, including site visits. Issues are assessed on a case-by-case basis and decisions on how best to address the issues are made by the relevant stakeholders. Reconciliation reports and action plans are revised each quarter.CITATION:Burns, T and Savory, P, 2014. Reconciliation of orebody model predictions – system and people, in Proceedings Ninth International Mining Geology Conference 2014 , pp 367–376 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 18, 2014

By M. J. U. T. Van Wijngaarden, R. J. Dippenaar

An electrochemical technique based on the solid oxide galvanic cel Mo / Mo + MoO2/ ZrO2-MgO / Fe + (FexO)slag + Ag / Fe was used in a determination of FexO activities in liquid slag systems. The emf measurements, scanning electron microscopy, and microprobe analysis of the cross-sections of the electrolyte tubes used in direct contact with the slag melts indicated that slag attack did not affect the open-circuit emf values during normal cell operation, The reliability of the cell was confirmed by the good agreement between the standard free energy of formation of liquid Fep obtained in the present study and those reported in the literature, The FexO activities were determined in FexO -CaO and FexO-SiO2 slags at 1673 K, and are in good agreement with those measured by the conventional gas-equilibrium technique. The experimental technique was successfully extended to the measurement of Fe2O activities in the complex slags that are used for the external desilliconization of the hot metal product of the blast furnace.

Jan 1, 1986

By G. E. Perry, R. D. Seba

The steam soak process is the most widely applied and most successful thermal supplemental recovery process in use today. This process, which consists of injection of steam in various quantities into a well that is subsequently used as a producer, can be repeatedly applied to the same well. The treatment, if successful, will increase the production rate of the well for a given period. For this reason, the steam soak process should be considered primarily as an acceleration method rather than as a method for producing oil that could not be recovered by primary means. However, application of this process to reservoirs containing viscous crude may produce oil that otherwise would have zero present value or would be produced at such low rates by primary methods that it would not be profitable. A major necessity for the successful application of the steam soak process is a source of natural energy. This source of energy may exist in one or more of the following forms: expansion of fluids, compaction, gravity drainage. This study was undertaken to determine the effect of gravity drainage on steam soak production and recovery and to develop a method for predicting production rates, ultimate recovery, and heat requirements when applying this process to a reservoir in which the primary driving mechanism is gravity drainage. (For additional discussion of some of the factors that affect recovery of viscous oils by the steam soak process, see Ref. 5.) Model The model developed for analyzing the performance of the steam soak process in gravity drainage reservoirs is a modified form of that developed by Matthews and Lefkovits.1,2 The model used in this study consists of two concentric cylindrical volumes of productive formation with cap and base rock of impermeable material. The inner cylinder, extending from the radius of the wellbore to some predetermined radius, is referred to as the hot zone; and the outer cylinder extending from the exterior boundary of the hot zone to the outer drainage boundary will be referred to as the partially heated zone. Fig. 1 is a schematic cross-section of the model, indicating its thermal properties. Horizontally the reservoir is divided into two regions, the upper region having a high gas saturation and residual liquid saturation, and the lower region containing a high liquid saturation. The boundary between these two regions is referred to as the free surface, which drops and changes shape as fluid is produced from the reservoir. The model was used to analyze the steam soak process by applying the following assumptions: 1. The horizontal formation is composed of one or more homogeneous noninterconnected layers containing incompressible fluids. Each layer is treated separately. 2. The hot zone is heated by the initial soak and is maintained at the steam temperature corresponding to atmospheric pressure by resoaking. 3. The height of the free surface at the producing well is at all times zero (producing well is pumped off). 4. The position of the free surface at the start of

Jan 1, 1970

By Frank Haas

THE public generally has-become aware that there is something wrong with the coal industry and a clamor has arisen for an explanation if not a remedy for this disorder. It is only reasonable that this Institute be looked to for a diagnosis to show the way for some other .agency to prepare the patient for prescription or operation. The subject is extensive, widely diversified, and beyond the efforts of an individual to cover completely; one of the objects of this paper is the initiating of a symposium on the non- technical factors essential to an understanding of the bituminous coal industry. The present condition of the coal industry cannot be described in a few words but, in effect, it resolves itself into a simple statement: The average coal operator is losing money notwithstanding a firm conviction on the part of the consumer that he pays too much for his coal. Without enumerating the many and varied. factors which contribute to this condition, this paper will be devoted to the interrelation of taxation and ownership of coal and its effect on finance

Jan 1, 1930

By Patzen Wu

The Hai-Shan No. 1 Coal Mine, located in northern Taiwan, is one of the typical coal mines on the island which, limited by natural condition, are mostly small in scale. With the advancing longwall method, the mine is now winning a seam, 80 cm thick, at a 32° dip, with a working depth of 824 m below surface. The annual output is about 50,000 mt of clean coal. At the working gallery, the virgin rock temperature may go up to 46°C, difficult to be brought dam to n acceptable level: because .of the tropical climate with high intake temperature and high humidity. Besides, at this depth, the intake air that goes down the long inclined shaft generates considerable heat due to autocompression. The mine is ventilated by a set of axial-flow fan with 38 m3/S of intake air at 2.2 KPA WG. With this volume of air, the temperature at the working-face is usually above 30°C WB. Appreciable lowering of the temperature is not expected even with an increased volume of ventilated air. For this reason, decision has. been made to try the installation of a pilot underground refrigeration unit near. the lowest gate road to cool the intake. air. from 32°C WB to 28°C WB which seems acceptable to on-the-spot workers exerting heavy physical labor. The experimental unit is designed for carrying away a total heat load of 90 Kw. The capacity of the unit is 200 Kw. The unit consists of a compressor, an evaporator, a condensor and a motor. The heat rejection is done in a cooling tower. Chilled water is circulated from the evaporator to the cooler by insulated pipes. The cooler consists of 90 Kw-coils with two fans and forces air by flexible ducting onto the working face. This paper examines mainly the effect of this additional reduction of working temperature, on working efficiency of the workers. Another aspect of this experiment is to evaluate the overall economy of underground refrigeration in small-sized coal mines under tropical condition. The success of such an experiment may lead to wider application of refrigeration to render many of the deeper mines economically workable.

Jan 1, 1980

By G. St. J. Perrott, N. A. Tolch

"PURPOSE OF TESTSThe propulsive strength4 developed by the Cardox blasting device depends on the thickness of disk, weight of heater element, and weight of carbon dioxide charge. It might be supposed that the maximum weight of carbon dioxide that can be charged into the shell should give the greatest strength. However, according to the ballistic pendulum, the maximum weight of carbon dioxide with certain conditions of heater and disk has less propulsive strength than a smaller charge; in one condition of test a loss of 39 per cent in propulsive strength was noted. It is therefore of interest to study the effect of the variables that determine the strength of Cardox.ACKNOWLEDGMENTGrateful acknowledgment is made to A. B. Coates, associate mechanical engineer who developed the testing method for measuring pressures in the Cardox shell.DESCRIPTION OF DEVICEThe Cardox blasting device as fully described by the bureau in Report of Investiga¬tions 2920 (1929), consists essentially of hollow—steel shell, cylindrical in shape, an electrode, valve assembly, shearing disk, and discharge cap. The shell is prepared for use by inserting a heater element, closing the open end with a shearing disk, and screwing in place the discharge cap. The charge of carbon dioxide enters the shell through the electrode.The heater element is fired by an electric igniter of the match—head type. The heat released by the heater element completely gasifies the carbon dioxide and raises the pressure of the gas until it is enough to shear the disk."

Apr 1, 1931

In September 2003, a test was conducted to see if a115-mm- (4.5-in.-) diam Mocap Vari-Stem blasthole plug could improve the pattern of explosives using different top stemming material. The test took place at the J.S. Faulkroad and Sonsstone quarry in McCalisterville, PA. The test consisted of a production stone blast. Half of the holes were stemmed with standard crushed stone. Two-thirds of the remaining half were stemmed with Vari-Stem plugs and crushed stone. And the remaining one-third of the second 50 percent was stemmed with Vari-Stem plugs and only drill cuttings.

Jan 1, 2004

By A Scott, S Kanchibotla, J Segui

The æMine to MillÆ concept is not new. In fact, it is the underlying objective of every mine. Unfortunately, in many operations the management structure and reporting systems have created independent æbusinessesÆ within the overall mining enterprise. This has created incentives to optimise the performance of each component of the operation rather than the enterprise as a whole. The Mine to Mill Conference organised by The AusIMM in October 1998 documented a number of case studies where run of mine ore was not presented to the mill in the best possible form for subsequent stages of comminution and processing. A number of examples were quoted where modest expenditure in the mine had a very significant impact on downstream process efficiency and hence costs. Examples included:the minimisation of fines in the mining and handling of iron ore; the management of fines in blasting and crushing for a copper heap leach operation; the control of blast damage, mining recovery and dilution in open cut coal operations; and the optimisation of mine fragmentation to increase mill throughput in gold and copper operations. The latter topic has been trialed at a number of mines and is referred to as æMine to MillÆ fragmentation. A number of æMine to MillÆ type investigations have been reported in the literature including Pease et al, Simkus and Dance, Nielsen, Scott et al, Kojovic et al, Kanchibotla et al, Bulow et al and Hawkes from the 1998 Mine to Mill Conference. In addition, a number of studies are in progress or the results have yet to be published. These studies have demonstrated the feasibility of obtaining the data required to characterise the breakage behaviour of ores and to model the impact of changes to blasting practices on process efficiency. Characterising the breakage behaviour of ores is a vital step in the management of fragmentation and comminution in mines. The characteristics of importance to fragmentation fall outside the parameters conventionally required to describe the economic geology of a deposit. æMine to MillÆ optimisation of fragmentation means that the mining engineer needs information from the geologist in order to be able to help the metallurgist. Providing this information requires close interaction between these groups.

Jan 1, 2000

By A. K. Singh

Between the main fan and the coalface in a mine a lot of air is lost through leakage at stoppings, doors, air-crossing etc. so that a much larger quantity of air has to be circulated by the fan in order that the stipulated quantity of air reaches the face. Stoppings are of vital importance not only for effective ventilation of underground mines but also for isolation of areas affected by fire or susceptible to spontaneous heating. Generally, isolation stoppings are made of brick in cement mortar. If the area is far from the pit or unapproachable, it is very difficult and sometimes impossible to build these stoppings. To overcome these difficulties, particularly near fire affected zones, an alternate successful attempt was made in Indian mines to make a plug underground, from surface through borehole, using cement concrete. In this paper the salient features of the methodology adopted for construction of the plug and the experimental procedure for the measurement of air leakage by SF6 tracer gas is described. Measurements of air leakage through rows of ventilation stoppings in two mines viz. Moira (Jambad and Kajora seams) and Kuardi11/12 (Niga seam) collieries of Eastern Coalfields Ltd. (ECL) have been incorporated. Results of experiments conducted at the Central Mining Research Institute (C.M.R.I) to determine leakage through25 and 38 cm thick brick stoppings are also discussed. Results of all these studies are compared, which show that the efficacy and reliability of the remote filled cement concrete plug in respect of air permeability is satisfactory.

Jan 1, 2004

By F. Mielli

Ranging between 20% and 40% of the typical mining operational costs, energy in mining operations is a growing concern for the industry. However, this concern is a complex, multi-faceted variable that involves government regulations, societal pressures, cost and competitiveness. A mining company successful in energy efficiency is becoming the standard of a successful company. The suggested energy strategy in mining and mineral processing operations has to follow a well structured approach that entails the following: ? Understanding where energy is being used and why, ? Recommending and implement energy conservation measures, ? Driving visibility to targets and results, ? Leveraging the energy spend across the enterprise, ? Developing a robust energy and sustainability strategy.

Jan 1, 2012

By Richard C. Marshall

The heightened concern over the environment which has developed in recent years has caused activities on National Forest lands to come under more intense public scrutiny. This has been especially true for activities oriented toward the production of commodities. Cattle grazing, mining, timber harvesting, and oil and gas leasing and drilling have all been increasingly subject to appeal and litigation. As a result, environmental analyses being conducted by the Forest Service have become more comprehensive, and measures to reduce or eliminate adverse impacts on resources have been given more attention. The costs of such environmental mitigation measures can be significant even when viewed in the context of the millions of dollars a company may spend, for example, to develop a mine. Using the Montanore Project in northwestern Montana as a case study, this paper examines the costs of alleviating some of the detrimental effects which may occur as a result of a mining operation. Although many of the general issues that have been raised about Montanore are common to other mineral projects, the scale of the project, as well as the fact that the ore body is within a wilderness area, the site is in grizzly bear habitat, and the surface waters are considered to be pristine, all combine to make Montanore particularly challenging from an environ- mental standpoint. Much of the information which follows is contained in the most recent version of the Draft Environmental Impact Statement (DEIS) which is scheduled to be published in several weeks. Based on agency and public comments, some of the information presented in the paper will change before the Final Environmental Impact Statement is issued in 1991.

Jan 1, 1991

By G. R. Love, M. L. Picklesirner

THE use of color adds a new beauty, power, and versatility to metallography. This has been amply demonstrated in a number of public exhibits and on the walls of corporate, government, and university metallographic laboratories around the world. Indeed, in a number of cases, the color not only is of esthetic value but is scientifically essential to the competent examination of particular samples and systems. Optical strain analysis,' determination of true grain size in U-A1 alloys: phase identification in Nb-base alloys,3 analysis of transformation rates in heat-treated Nb-Zr alloys,4 measurement of solidification segregation in cast Nb-Zr alloys,' study of the intermediate phases in Nb/Sn diffusion couples,6 investigation of the oxidation kinetics at various surface orientations in single crystals,7'8 and a number of other research efforts9'10 would have been vastly more difficult without the extra clarity and distinction introduced by color—either the colors resulting from particular polarized light techniques or the interference colors obtained by oxidation. It is unfortunate that the beauty of colored micro-structures cannot be shared more widely, but the economics of publishing a technical magazine apparently prohibits color plates except under extraordinary circumstances. It is doubly unfortunate that no convenient, general method exists for communicating the information available in colored microstructures to the scientific community. True, in some instances the color changes observed are dramatic enough that direct black and white photography is adequate. In photoelastic stress analysis, several orders of interference fringes may be produced and it is frequently desirable to suppress the color effects (use monochromatic light) to simplify interpretation. On the other hand, relatively minute color variations may be readily detectable by eye, be of considerable assistance in interpreting a structure, and yet be enormously difficult to reduce to an unambiguous black and white print. In order to illustrate a possible compromise or solution to the above problems, we wish to show three black and white photographs of the same region of an Nb/Sn diffusion couple whose interpretation depends heavily upon use of color techniques. These micro-structures were obtained from a section through a rod consisting of commercial-purity niobium tubing filled with 99.995 pct Sn (melt-filled in 10"6 Torr vacuum). The composite rod, measuring 500 mm long, was bent into a hairpin shape and inserted into water-cooled copper grips in a vacuum high-temperature furnace. The rod was outgassed for 2 hr at a furnace temperature of 800°C and was further heated by self-resistance using a 2.2-kva ac power supply. The rod was raised to 1910°C over a 4+-hr period, held for 15 min, slow-cooled to 1500°C over a -hr period, and free-cooled to room temperature (all temperatures were measured with W5Re/W26Re thermocouple). Throughout the heat treatment the ambient pressure was kept below 8 x lo-' Torr. Metallographic preparation of the sample was completely conventional except that it was necessary to extend the grinding steps to remove damage in the brittle NbsSn phase introduced by sectioning. No satisfactory chemical or electrochemical etch has been found for these diffusion couples; of those which have been tried, any that attack the niobium-rich phases at all attack the tin-rich phases disastrously. However, the final polishing steps did produce a slight relief effect and this, coupled with anodizing, yielded excellent clarity in the microstructures for direct observation. The anodizing voltage was chosen to give maximum change in color per unit change in composition. In this case, indeed normally, this maximum sensitivity occurred in the blue-to-red color range. The pure niobium tube wall anodized to a relatively bright blue

Jan 1, 1967

By Christoph Beckermann, Kai Liu, Richard A. Hardin

"A two-dimensional heat transfer model for transient simulation and control of a continuous steel slab caster is described. Slab thermal and solidification conditions are computed by the model as a function of time-varying casting speed, secondary spray cooling water flow rates and temperature, slab thickness, steel chemistry, and pouring and ambient temperatures. A solidification model that includes the effects of steel chemistry, cooling rate and mierosegregation on the solidification path is incorporated directly into the caster model. Comparisons between measured and predicted liquidus and solidus temperatures are given for two low alloy steels, and show good agreement. Predicted and measured slab surface temperatures recorded on an operating caster are compared with this transient model and show that the model can predict the temperature response at the slab surface. Results of several simulations are given to demonstrate the effects of changing casting conditions on the slab thermal profile and the solidification end-point. A control methodology suitable for online control of a continuous casting machine is described, and its ability to control the surface temperature profile by dynamically adjusting secondary spray cooling flow rates is demonstrated using the simulator. IntroductionIn order to remain competitive in today's world-wide market for continuously cast steel products, steel producers are finding that it is ever more important to implement process control and to develop a more thorough technological understanding of their casting process. By integrating process control and monitoring into both production and quality control, producers are better able to meet customers' demands for steel of the required quality, quantity, size, grade, and properties at the lowest cost. Computer models used for real-time/on-line prediction and control of continuous steel casters are fundamental tools to accomplish this. Accurate on-line prediction and control of steel solidification and heat transfer allows for more flexibility in caster operation by giving operators the ability to change casting speeds while keeping critical process parameters within required ranges. Such control 'capability also results in more uniform quality throughout an entire casting sequence from startup to shutdown. Furthermore, due to the unreliability of temperature sensors, and the lack of good sensors for important process parameters such as solidification end-point and liquid pool depth, computer-based control models are often the only available option."

Jan 1, 2000

By T M. Brettell, D Sidea

The CSA Mine is located in Cobar, New South Wales and is operated by Glencore. Large scale underground production started from 1965, with zinc, lead, silver and copper extracted in the past. The current operations focus on copper, with a silver co-product.From 2014 to 2016, Cobar Management Pty Ltd (CMPL) undertook a major capital project to upgrade the primary ventilation system at the CSA Mine. This involved the development of ten raises using full-face raise boring from surface to a depth of 1450 m. The total length of the raises was approximately 2500 m. Geotechnical conditions were identified as a key project risk during the early planning stages of the project. Timely quantification of the geotechnical risks was required to minimise project delays and cost overruns. Geotechnical investigations were planned and conducted for each raise prior to pilot drilling and full-face back reaming.Nine of the ten raises had final wall camera and laser baseline surveys completed following full-face reaming. The surveys were conducted progressively, allowing ongoing back analysis and calibration of geotechnical evaluations as the project advanced.This paper presents the design and planning process of the raise bored excavations. It details the geotechnical investigation work undertaken to mitigate the geotechnical risks and the challenges and learnings from the project including the benefits of close collaboration between the parties involved.CITATION:Sidea, D and Brettell, T M, 2017. The CSA ventilation upgrade – geotechnical challenges and learnings, in Proceedings 13th AusIMM Underground Operators’ Conference 2017, pp 341–352 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 16, 2017

By K. Niboucha, M. Zergoug, S. Brick-Chaouch, H. Houali

"Corrosion is an electrochemical process that causes degradation and deterioration of various steel works (pipelines, drains, cisterns) whether they are buried, immersed, or not. Worldwide, we estimate that corrosion destroys a quarter of the annual production of steel at a rate of 5 tons per second. Several techniques are used to protect against corrosion. Among these processes, Cathodic protection, which is regarded as the best technique to assure the protection of steel, works against this phenomenon. This is achieved either by a system of reactive anodes, or by the technique of impressed current protection or other techniques. Before any installation of cathodic protection, a preliminary study and pre-evaluation of certain parameters must be made. In the present work, we will present an example of dimensioning of an installation of cathodic protection by imposed current of a pipeline using solar energy, where we discuss the following items:•,Evolutions of the potential as well as current along the pipeline and their respective expressions deduced from the laws known as telegraphists;•,Range of protection (potential of protection along the pipeline);•,Influence of the isolation resistance of the coating on the range of protection;•,Effect of the aging of the coating and its influence on the current of protection."

Jan 1, 2005

By Abolfazl Eslami, Sepide Lotfi, Mohammad M. Eslami

"Via direct CPT methods for pile capacity prediction, correlation coefficients smaller than unity are used to relate cone tip resistance (qc) and sleeve friction (fs) to pile toe capacity (rt) and shaft capacity (rs), respectively. For linking CPT data to pile capacity, factors such as diameter, penetration rate, partial embedment of pile toe into a hard layer, mechanism of plunging, failure zone, data processing, and stress-strain conditions must be considered. The aim of this paper is to investigate the role and significance of scale effects and establish direct relation between CPT data and pile shaft capacity. A database has been compiled including 40 full scale pile load tests and CPT sounding records for calibration and validation of the proposed approach. Analytical studies demonstrate that differences between pile and penetrometer penetration rate, geometry, and stress-strain conditions influence the relation between fs and rs. By considering the determinants, a procedure is proposed from which the pile shaft capacity can be predicted. This approach demonstrates better agreement with measured capacity by static loading test and less scatter than other current CPT methods.IntroductionAmong different approaches for pile capacity prediction, in-situ tests such as SPT and CPT have been used as supplementary of static analysis. Due to similarities between CPT and pile, the measured cone tip resistance and sleeve friction can be employed for prediction of unit toe and shaft capacities, respectively.Determination of pile capacity from CPT data includes two main approaches: direct and indirect methods. Direct CPT methods apply the measured values of cone tip resistance (qc) for pile toe capacity (rt), and sleeve friction (fs) for pile shaft capacity (rs) with some modifications regarding scale effects. Indirect CPT methods employ friction angle and undrained shear strength values that have been estimated from CPT data.When using direct CPT methods to relate qc and fs to rt and rs, correlation coefficients smaller than unity are used. Factors such as diameter, penetration rate, mechanism of plunging, failure zone, data processing, and stress-strain conditions must be considered for correlation between CPT and pile capacity. The work presented in this paper aims toward ameliorating the situation in the area of pile shaft capacity prediction, based on cone sleeve friction.Case histories from full-scale tests are compiled and analyzed by means of six methods including five direct CPT methods for shaft capacity prediction and the proposed method."

Jan 1, 2015

By B. Silliman

The experiments detailed by Dr. Hunt,* having demonstrated the fact that the copper contained in the "clay ore" of Jones's Mine, was rendered completely soluble in the bath of ferrous chloride, used in the Hunt and Douglas process, after heating in contact with carbonaceous matter in a close vessel, I set myself to devise a form of muffle furnace adapted to the treatment of large quantities of these and similar ores by a continuous process. The result is shown in the diagrams on Plate X, reduced from the working drawings, after which this furnace was built early in 1876, at Phœnixville, by the Chemical Copper Company on their works at this place. The peculiar character of this ore determined the form, dimensions, and position, with reference to charging and discharging of these muffles. The ore arrived from the mine with from 20 to 25 per cent. of moisture, and when dried at 21o F., or more slowly at lower temperature, it falls to a light incoherent powder, with occasional lumps of undecomposed rock. In this condition it is readily mingled with coal-dust or any like reducing agent, and requires no other preparation for the muffle than the use of the shovel, to mix it well with the reducing agent. As it is a remarkably good non-conductor of heat, it was obvious that the mass, to be heated through in a reasonable time, must not be too thick, while the weight of the mass must be sustained in a way to avoid undue strain upon the walls of the muffle. These walls must be as thin as practicable, to favor the more rapid transmission of heat, and must, therefore, be so constructed as to admit of being stayed on the sides at frequent intervals to resist the lateral thrust of the very mobile mass of pulverulent ore, which, for obvious reasons, must be charged at the top and drawn from the bottom of each chamber. These considerations led to the form adopted, viz., two vertical muffles, standing upon very strong bridge tiles, seen in longitudinal section, on the line E, F, and in plan in Fig. 3, on the same plane. (Plate X.) The vertical section of the muffle is seen in Fig. 4, drawn in the plane G, H, of the longitudinal section, Fig. 6, which is the key to all sections. The walls of the muffles are built of the best firebrick, very care-