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

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

Jan 1, 2016

AN announcement of the annual meeting to be held in New York, Feb. 14 to 17 inclusive is being mailed to all members. Particular attention is called to the necessity of asking for certificates when you purchase your ticket in order that all may secure reduced return fares.

Jan 1, 1927

By Charles W. Dickson

Jan 1, 1904

By A. Tello

Variography was introduced by Dr. Pierre Gy to monitor a process, in the sixties. Later on, Francis Pitard extended this concept, building a complete system of variographic controls for different applications. Nevertheless, the existence of information about its use as a way to effectively control plants has been limited. There are infinite areas where variography and chronostatistics can be used. In this paper, two different cases related to gold and silver recovery, through well known but complex metallurgical routes are studied. The use of effective management of process variability software (EMPV) has shown to be a suitable solution to clarify problems at the plant and, consequently, a solution to the encountered problems has been proposed. Chronostatistics is like opening a new world to the metallurgist, making the process variability speak in a more comprehensive and in depth way. Once the ore has been extracted from the mine, sampling is necessary at each sequence of the metallurgical process involved. As a first example, leaching of the ore with cyanide in agitated tanks is another case of a complex metallurgy. The aim of the process is to know about residual values in the tailings in order to optimize process. As a second example, leaching of gold and silver in ore heaps, has to be optimized in terms of time, reagents consumption and, of course, in predicting a reasonable recovery. This last issue appears to be crucial. After cyanide leaching at the heaps, a carbon in columns process is involved, where there are a series of carbon loaded columns that are submitted to a dynamic process of load and unload, to finally deliver an enriched solution to the precious metal electrowinning plant. In both cases, variography has been a good approach to show metallurgists ways to improve the operation.

Jan 1, 2009

By Cristian Melipichun, Leopoldo Gutierrez

The effect of the presence of fine particles of kaolinite and montmorillonite on the induction time for attachment of bubbles to particles of a copper concentrate rich in chalcopyrite was evaluated in this study. The results obtained from induction time measurements were correlated with data of concentrate recovery achieved from micro-flotation experiments. The effect of the presence of fine clays on the stability of air-water foams was also studied through measurements of the foam volume generated in a glass column under different conditions of air flowrate and MIBC concentrations. The experimental results showed that induction time values increased under the presence of fine clays. These data agreed with results obtained from micro-flotation experiments that showed that copper concentrate recovery decreased when clay particles were added. Although a complete explanation for these results is not available, the fact that experimental observations indicated that fine clay particles tend to adsorb on gas bubbles, suggests that the interactions between fine phyllosilicate particles and air bubbles have to be taken into account when studying the effect of clays on froth flotation. Foamability tests showed that the presence of fine clay particles increased the foam volumes only at high additions of clays and low dosages of MIBC. The results obtained at higher dosages of MIBC showed that the foam volumes decreased with the addition of clays under all the experimental conditions tested.

Jan 1, 2014

By Sven Fornander

An account is given of the way in which a new process for desulphurization of hot metal is carried out at a Swedish blastfurnace plant. In the process powdered burnt lime is used as a desulphurizing agent in a rotary furnace. Results are given. IN a paper by Kalling et al.* the fundamentals of a new process for desulphurization of hot metal using powdered burnt lime as a desulphurizing agent were outlined. The purpose of the present paper is to give a brief account of the way in which this process is being carried out in practice by Surahammars Bruks AB, Sweden, and of the results obtained. + The hot metal from the blast furnace is tapped into a ladle of 15 tons capacity and transferred to a rotary furnace, a simplified drawing of which is given in Fig. 1. The rotary furnace has a total length of about 160 in. and an outside diameter of the rings of about 130 in. The furnace is in a horizontal position, with its rings placed on four rollers, and can be rotated by a driving mechanism at various speeds of up to 34 rpm. The rotary furnace and its driving mechanism were designed and constructed at Surahammar. The hot metal is charged into the rotary furnace through the opening to the left in Fig. 1. See Fig. 2. An addition is then made to the furnace consisting of finely ground burnt lime amounting to 2 pct of the weight of the hot metal as well as 0.5 pct of coke breeze. After the additions are made, the furnace is sealed to the atmosphere by means of two lids and set in rotary motion at a rate of 34 rpm. The sulphur in the hot metal is rapidly absorbed by the lime added, the time of treatment needed is normally 30 min. The process is then stopped, the lid is removed, and the furnace is lifted up by a crane and used as a tilting ladle for pouring the metal into the pig-iron molds, Fig. 3. Process Metallurgy The hot metal charged into the rotary furnace has a composition which usually lies within the following limits: C, 3.70 to 4.10 pct; Si, 0.80 to 1.80; Mn, 0.40 to 0.80; P, 0.025 to 0.030; and S, 0.060 to 0.200. Figs. 4 and 5 give examples of the changes in hot metal composition taking place during the treatment in the rotary furnace. As will be seen from the diagrams, the sulphur content of the metal decreases very rapidly during the first 10 min of treatment from about 0.100 to about 0.020 pct S. During the following 20 min, the sulphur content goes down slowly to about 0.005 pct S. The carbon and silicon contents of the metal decrease by about 0.10 pct each during the treatment. The manganese and phosphorus contents remain unchanged. Thus, if the process is started with an iron of the composition given above, the finishing composition of the metal usually lies within the following limits: C, 3.60 to 4.00 pct; Si, 0.70 to 1.70; Mn, 0.40 to 0.80; P, 0.025 to 0.030; and S, 0.002 to 0.020. The chemical reaction taking place during the process can be written:

Jan 1, 1952

By L Rachmad

Freeport IndonesiaÆs Deep Ore Zone (DOZ) mine is the new underground block caving mine within the East Ertsberg Skarn System (EESS) deposit which started production in mid-2000. The DOZ will produce 25 000 tpd using mechanised block cave mining method and will be the fourth underground mine opened within the EESS deposit. Evaluations were made on former block caving mines at PT Freeport Indonesia (IOZ, GBT Area I and II) in order to design a more appropriate support system. As a permanent support, the thread bar bolt support system is widely used in the DOZ mine. The advantages of this system are ease of operation, quality control and high bond strength. The main problem of this system is the curing time of about 28 days to achieve maximum strength, necessitating the installation of a temporary support for its implementation. In this instance, the system was inefficient in operation and studies were required to find an alternative grouting system. This paper examines the evaluation of thread bar bolt support system and compares the performance of two types of grouting (resin cartridge and cement cartridge) with cement grouting performance. The evaluation is conducted with a pull out test. The advantages and disadvantages for each grouting method, comparison of cost estimation and grouting application in mine scale are presented in this paper.

Jan 1, 2002

By B. Erdem, N. Çelebi

An important problem associated with tandem dragline systems is that of matching the productive capability of individual draglines in the combination. In this paper, a dependence mechanism among draglines in a tandem system is described, and possible consequential problems in a poorly-matched system are defined. The rate of linear advance and the cost of stripping are determined as two major indications for an efficient operation. The proposed decision criteria and the underlying mechanism to select a synchronous couple are introduced and used in simulating tandem dragline systems. The developed model is tested on a hypothetical strip mine where pullback stripping is applied with a tandem dragline system.

Jan 1, 1999

By J. S., Douglas

IN 1880, the late James Douglas, LL.D., was superintendent of the Chemical Copper Co., operating the Hunt & Douglas process for the treatment of the siliceous copper ores of the Jones mine at Phoenixville, Pa. In conjunction with this a refining furnace was operated. After correspondence with Ben Williams, of Bisbee Ariz., who was commencing the mining and smelting of the Copper Queen ore. Dr. Douglas decided-to make his first journey to Arizona. While making plans for the trip lie visited a friend in Philadelphia, a .Mr. Logan, a prominent lawyer. He, through Professor Treadwell, brother of the discoverer of the great Treadwell gold mine of Douglas Island, Alaska, had an option with his min¬ing partner, Mr. Lenig, on the Eureka and Wade Hampton claims near the headwaters of the Verde River in Yavapai County, Arizona. These two claims, later the source of practically all of the wealth of the Jerome district, were then owned by C. P. Head and Co. Prescott merchants. Hugo Richards, banker, and formerly sutler at Camp Apache; Rod and John McKinnon prospectors and Nova Scotians; and perhaps one or two 'other owners of minor interests. Mr. Logan, hearing of Dr. Douglas intended trip to Bisbee, asked him to go first to see the two mining prospects, and this, Douglas, in need of the $500 fee, agreed to do as the time on the option on the claims was running short.

Jan 1, 1935

By James Westfield

Following is a resume of activities of the Division of Coal-Mine Inspection that have had a favorable effect on health, safety, and the reduction o1 injuries at coal mines: 1. The Federal Mine Safety Code for Bituminous Coal and Lignite Mines of the United States was issued originally by the Director of the Bureau of Mines July 24, 1946, after consultation with management and labor representatives of the coal-mining industry. The code has been used by Federal coal-mine inspectors while inspecting bituminous coal and lignite mines as a basis for determining the existence of unhealthful and unsafe conditions and practices in these mines. A revised code was issued by the Secretary of the Interior October 8, 1953, after further consultations with representatives of management and mine workers and was incorporated by reference in the 1952 and subsequent bituminous coal wage agreements. The agreement of May 29, 1946, between the Secretary of the Interior, acting as Coal Mines Administrator under authority of Executive Order 9728, and the United Mine Workers of America, covering bitumi¬nous coal and lignite mines in Government possession, charged Federal coal-mine inspectors with the responsibility of making periodic investigations of the mines and reporting to the Coal Mines Administrator any violations of the Federal Mine Safety Code. Federal coal-mine inspectors also had temporary authority to close mines found to be imminently dangerous, but such authority (under Executive Order 9728) was removed June 30, 1947, when Government control of the mines was terminated.

Jan 1, 1959

By Faruk Oksuz, Cary Hirner, Ray Brainard

"Key project participants, including owners, engineers, and contractors continually seek for sound and structured decision analysis on how to select the best contracting method for successful project delivery. In addition to being burdened with technical challenges, lack of resources, budget shortcomings, regulatory requirements, and bureaucratic and politically mandated obstacles, the project participants need a reliable decision analysis model on the best project delivery method. The pendulum of choice for contracting continually swings back and forth between traditional design-bid-build and alternative delivery options such as design-build, progressive design-build, construction manager at risk, and public-private-partnership. For large tunnel projects, the decision process is further complicated due to contract packaging options as well as risks in underground construction. Contracting strategies for large tunnels require thorough consideration of performance, risk, quality, operability, cost and schedule. This paper compiles an array of decision making criteria and tools for an unbiased and balanced evaluation and ranking system in the procurement of large tunneling projects. INTRODUCTION Successful project delivery hinges upon meeting the owners’ expectations and key performance indicators. Large tunneling programs benefit from a thorough understanding and successful implementation of project delivery options by key project participants including the owners, engineers and contractors. The key to success is a collaborative advancement of project as the key project participants knowledgably address the applicable management, performance, risk, quality, cost, operability and schedule considerations throughout a project realization cycle. PROJECT REALIZATION CYCLE All projects have customary planning, design, construction, commissioning and operation phases that may seem to be sequential but in reality that are well integrated and dependent on one another. A glitch in any phase of a project realization cycle could hinder a successful outcome and none of the project partners are immune to consequences whenever and wherever they may surface."

Jan 1, 2016

By S. T. Johansen, B. T. Løvfall, T. Rodriguez Duran

In this paper we develop a physics-based model for lining erosion in steel ladles. The model predicts the temperature evolution in the liquid slag, steel, refractory bricks, and outer steel shell of the ladle. The flow of slag and steel is due to forced convection induced by inert gas injection, vacuum treatment (extreme bubble expansion), natural convection, and waves caused by the gas stirring. The lining erosion takes place by dissolution of refractory elements into the steel or slag. The mass and heat transfer coefficients inside the ladle during gas stirring are modelled based on wall functions which take the distribution of wall shear velocities as a critical input. The wall shear velocities are obtained from computational fluid dynamics (CFD) simulations for a sample of scenarios, spanning out the operational space, and a model is developed using curve fitting. The model is capable of reproducing both thermal and erosion evolution well. Deviations between model predictions and industrial data are discussed. The model is fast and has been tested successfully in a ‘semi-online’ application. The model source code is available to the public at [https://github.com/SINTEF/refractorywear].

Apr 16, 2024

By Jonguk Kim

Submarine hydrothermal activity and mineralization related to island arc volcanism along the Tonga arc were explored during two research cruises in October 2009 (KODOS 09H) and February 2010 (KODOS 10H), respectively. In KODOS 09H cruise, geophysical survey, including multi-beam bathymetry, marine seismic and magnetic investigations, was performed on 10 volcanoes to find out possible structural discontinuity that can act as fluid pathway for formation of hydrothermal deposits at submarine caldera system. The result provided acoustic and seismic image maps and magnetic anomaly maps of targeted volcanoes. Then, detailed seafloor observation and sampling as well as deep tow side scan sonar survey were performed in KODOS 10H cruise on 5 volcanoes which are selected as targeted areas from the previous cruise. Among 5 targeted volcanoes, TA26 shows most extensive hydrothermal activity. Hydrothermal vents and alteration zone were observed on western caldera and summit of eastern cone of the TA26. Although only weak hydrothermal alteration was observed on eastern cone, mineralized fragments of chimney and mound were sampled from western wall of central caldera on TA25 volcano. On TA12 volcano, strong hydrothermal plume and alteration zone was detected during video tows operated between SW scoria cone and small ridge. However, only small amount of hydrothermal altered rocks were collected from TA12. Although hydrothermal activity and mineralization might be formed, supported by plume detection and result of geophysical survey, only weak alteration zones were observed on other two volcanoes (TA19 and TA22). The exploration area generally show shallow depth up to several tens of meters on summit where subsurface boiling of hydrothermal fluid might occur due to low hydraulic pressure, which can affect on styles of hydrothermal venting and mineralization process observed on Tonga submarine arc volcanoes.

Jan 1, 2010

By Arthur B. Foote

THE ball mill has superseded stamps for the reduction of gold ores in most of the recently designed plants, partly because stamps are not suited to die fine grinding required for flotation, and partly to save space and construction cost. Experience with these new mills seems to confirm the idea that it is more difficult to recover bold from a ball-mill product than it is when stamps are used for crushing. Microscopical examination of particles of gold that have passed through a ball mill show that the gold has been pounded into exceedingly thin flakes coated with a talcy surface, making it more difficult to save by amalgamation, flotation, or concentrating. Bearing in mind that gold is extremely malleable, it seems reasonable that this should be so. Contrast the action in a stamp battery, where the crushing is by impact in the presence of mercury, to the grinding and rolling under pressure in a ball mill. It is well known that a better recovery can be obtained by panning or amalgamation from a sample of ore that has been crushed by mortar and pestle than from one reduced on a bucking board.

Jan 1, 1937

By D. Saramak

The proposal of the nip zone angle determination in HPGR crushing process is presented in the paper. Knowledge of the nip zone angle value, in turn, makes it possible to determine the real maximum pressing force in the high-pressure comminution. Two methods of determination of this maximum pressure were proposed and verified. The first method is based on the roll?s geometry, and the change of the HPGR chamber?s volume together with the roll rotation, while the second one considers the outlet gap width impact. Results of the nip zone angle calculations according to both methods are similar and show convergence with the real operating conditions. The verification was carried out in a piston-die press, and experimental results show that methodology of the nip zone angle determination presented in the paper has its practical confirmation. A proper determination of the nip zone border makes it possible to calculate the comminution probability of given type of material and is a basis for the HPGR crushing process modeling and optimization. Keywords: HPGR, comminution, nip zone, ore processing

Sep 1, 2012

By Thierno FALL

This paper describes the study of the work-roll during the hot rolling process thanks to a 3D model built with the Finite Element Method (FEM). In terms of computational cost, that method needs high resources compared to 1D model which are mostly used. However, the 3D model is built to have a better understanding of the work-roll thermal and mechanical behavior during the hot rolling process. The thermal model shows that the highest temperature reached during rolling are within the range of 500°C and 600°C. The thermal field input used to simulate the mechanical behavior of the work-roll shows a biaxial thermal stress state, in the circumferential and axial planes. However, a peak of radial stress is observed in the backup zone. It did not generate plastic strain but could influence the fatigue behavior of the work-roll.

Oct 1, 2019

By Ivan César Lopes Diniz, César Romero Afonso Goulart Júnior

Mandrels are tools applied to manufacturing seamless tubes. In VSB plants (Vallourec Soluções Tubulares do Brasil), it is used in two mills. Mandrel and PQF Mills. This is an expensive tool due its alloy (hot work tool steel – AISI H13) and lengh (between 12 meters and 22,5 meters). An opportunity to apply mandrels from PQF in Mandrel Mill has been identified. However, mechanical properties of PQF mandrels must be improved. This work presents the heat treatment process of Quenching and Tempering developed internally at VSB to improve PQF mandrel properties aiming to achieve Mandrel Mill requirements. Hardness and metallography tests were performed before and after some steps of the heat treatment to characterize and validate the process.

Oct 5, 2019

By Y. Lahaye, O. Martinsson, B. I. Palsson

"Four main and three minor rare-earth-element (REE)-bearing minerals were identified and quantified in the Kiirunavaara apatite iron ore tailings using optical microscopy, an electron probe microanalyzer (EPMA) and a mineral liberation analyzer, and their chemical compositions were analyzed by the EPMA and laser ablation inductively coupled plasmamass spectrometry. REEs are shown to be contained in the minerals apatite, monazite, allanite, titanite, zircon, thorite and synchysite. In zircon, thorite and synchysite, they occurred in only trace amounts and contributed limited amounts to the total REE budget, and these are consequently of minor importance. Monazite occurred as inclusions in apatite and as free particles, 90 percent liberated. Allanite occurred to some degree in mixed grains with magnetite but also as free particles. Monazite mainly reported to the apatite concentrate, while allanite and titanite largely went to the tailings, the latter preferably to those fractions smaller than 38 µm. The amount of titanite in the finest tailings fraction was 2.3 weight percent, containing close to 1 percent REEs, with heavy rare earth elements (HREEs) making up 28 percent of the total REEs. However, a texturally distinct group of titanite grains showed an HREE/REE ratio of up to 67 percent. Furthermore, titanum dioxide analyses indicate that titanite is preferentially released into the tailings from the secondary magnetic separation step in the concentrator. Our data therefore suggest that titanite, occasionally enriched in HREEs, can be extracted from the processing stream and might thus be considered a new source for REEs at Kiirunavaara and similar deposits.IntroductionDeposits of apatite iron ores are the major source for iron in the European Union and are exploited by Luossavaara-Kiirunavaara AB (LKAB) in several mines in the Kiruna-Malmberget area in northern Sweden. Kiirunavaara is the largest of the apatite iron orebodies in Sweden, comprising more than 2 Gt of iron ore with 60 to 68 percent iron (Fe). At the end of 2015, the total accumulated production of crude ore from openpit and underground mining since the start of mining was 1,566 Mt, with ore reserves of 644 Mt grading 46.3 percent Fe (LKAB, 2016). The deposit defines a steeply dipping tabular body, approximately 6 km long and up to 180 m thick, extending at least 1,500 m below the surface. It is situated in the middle part of the Palaeoproterozoic Kiirunavaara Group of volcanic rocks and follows the contact between a thick pile of trachyandesitic lava and overlying pyroclastics (Martinsson, 2004)."

Jan 1, 2017

By X. Q. Jiang, D. L. Chen, A. Macwan

Magnesium alloy, being the lightest structural material, is a key candidate for the weight reduction of vehicles in automotive and aerospace industries; however, its poor corrosion resistance and difficulty in deformation are limiting factors. Recently, Al/Mg/Al tri-layered clad sheets have been considered as a promising alternative to improve corrosion resistance and formability of magnesium alloys. The aim of this study was to evaluate the tensile properties and deformation behavior of Al/Mg/Al tri-layer clad sheets at different temperatures and strain rates. Yield strength (YS), ultimate tensile strength (UTS), and elongation were observed to increase with increasing strain rate. With increasing temperature from -40°C to 180°C, YS and UTS decreased and ductility increased. The strain hardening exponent evaluated via three equations of Hollomon, Swift, and Afrin et al. showed a similar increase with increasing strain rate and decreasing temperature. The fractographic analysis showed partial debonding of clad interface especially at higher strain rates and lower temperatures.

Jan 1, 2015

By D. Brandt

The Dos Pobres Mine is a copper oxide heap-leach operation located near Safford, AZ. Mine production is 163 kt/d (180,000 stpd) with a stripping ratio of 2:1. During the startup phase of the mine, the required fragmentation size was easy to achieve as the ore was highly weathered and fractured near the surface. As the mine depth increased, the proper fragmentation size became harder to achieve due to less weathering and different rock types. Because copper recovery increases as crusher product size decreases, achieving the appropriate product size at the crusher is the operating priority. The engineering department began a project to improve fragmentation through blasting and thus increase throughput in the crushing system. It soon became clear that input from other departments was going to be required to make this a safe and economical project. Therefore, the crush and convey and ore control departments worked together to evaluate all available data on blast patterns and explosive loads and tracked performance and results. Using image analysis, drill energy index and databases, improved fragmentation size has been achieved and results have been verified while controlling costs.

Jan 1, 2011