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By Jorge Olivari Ortega

"El presente texto describe la historia del inca Huiracocha y la explotación con los filones de oro del Ritisuyo. Durante el proceso de expansión del imperio incaico, los dominios territoriales de Hatun Inca o ""Huiracocha, el octavo gobernante, alcanzaron por el sur, hasta la última población de las Charcas (en la actual República de Bolivia); por el oeste, hasta las orillas del Océano Pacífico; y por el oriente, hasta la Cordillera Nevada o Ritisuyo, donde existían riquísimos filones de oro. Así, los incas denominaron ritisuyo (de los términos quechua: riti, nieve y suyo, región) al espacio geográfico de los Andes que supera los 4,500 metros sobre el nivel del mar y está cubierto con nieves, donde muchas veces asoman o afloran filones de oro en su superficial. Los filones son depósitos de minerales con contenido aurífero que fueron explotados por los incas -particularmene por el corimayco (encargado del trabajo minero) a través de socavones, el cual consideraba la dureza del terreno y además, el curso de la estructura mineralizada (rumbo y buzamiento)."

Jan 1, 2016

By Jeffrey R. Hill

To extend the life of the Merchants Railroad Bridge crossing the Mississippi River in St. Louis, MO, the owner implemented a rehabilitation and reconstruction project. The Merchants Bridge provides a key link in the transcontinental railroad system. The bridge is of local importance to the Terminal Railroad Association ? providing a link between St Louis and a rail switching yard in Venice, IL. The intent of the bridge rehabilitation is to keep the Merchants Bridge in service, even though the bridge was originally constructed in the 1890?s. The project involved replacing the East and West approach deck truss spans with new deck girder spans. The rehabilitation program required construction of new concrete piers to support the new spans. In order to reduce the track down time to two, ten day single track shutdowns, the specifications required that all foundation and substructure work be completed while leaving the existing spans in place. The preliminary bridge design specified rock-socketed drilled shaft foundations. Drilled shafts proved to be challenging due to working from beneath the existing bridge, a high water table, utilities, a flood wall, and existing rail way lines. The micropile alternative was technically appropriate given the access limitations, shortened the foundation rehabilitation schedule by several weeks, and realized a significant cost savings to the Owner.

Jan 1, 2006

By Eduardo Viedo Moreira

Analisou-se o tratamento térmico de revenimento de grampos ferroviários, modelo E2039AV, feitos a partir de barras redondas com aproximadamente 20 mm de diâmetro do aço SAE 9254 tendo como objetivo reduzir o tempo do processo de fabricação. A temperatura do forno foi mantida em 490ºC e 18 grampos foram imersos no sal fundido. Em grupos de 3, os grampos foram retirados em intervalos de 10 minutos, tendo o último grupo permanecido no forno por 60 minutos. Após cada retirada foram feitos os ensaios necessários para aferir a qualidade das peças: carga estática, dureza e fadiga. Após apenas 10 minutos de revenimento os grampos já resistiam ao mínimo de 1.000 kgf sem fraturar e apresentaram medidas de dureza próximas ao limite superior de especificação, ou seja, a dureza que era aproximadamente 58 HRC antes do revenido, atingiu valores próximos a 48 HRC. O último teste, fadiga, foi feito apenas nos grupos de grampos revenidos por 30 e 50 minutos. Pôde-se concluir que é possível reduzir o tempo de revenimento do grampo E2039AV feito de aço SAE 9254 de 60 minutos para pelo menos 50 minutos mantendo-se a qualidade dos grampos sem a necessidade de aumentar a temperatura do forno.

Aug 17, 2017

By Arturo Ressi di Cervia

The utilization of diaphragm wall construction in Hong Kong began in 1974 with the construction of the New World Center, the first diaphragm wall job built in the British Colony. That landmark job of which I am presenting a few slides and a schematic description, embodied all of the difficulties and problems which are encountered in the difficult geology of Hong Kong. A small rocky island in the South China Sea, Hong Kong provides one of the finest natural harbors in the world. It is its splendid harbor, coupled with the enterprising attitude of the Hong Kong Chinese and the laissez-fair attitude of the British government which has resulted in the explosive growth of this speck of land soon to revert to the political control of mainland China.

Jan 1, 1993

By Cordner G. D

Titanium is not yet being produced on a commercial scale despite the facts that it has some impressive properties, and that it occurs very abundantly in easily-mined, highgrade oxide ores. One important reason for this is that the excellent mechanical properties of the metal were not widely recognised and appreciated until about twenty years ago.Another factor which has tended to retard progress in titanium metallurgy has been the realization that the oxide minerals of titanium are very stable; in other words, considerable energy has to be expended to reduce the oxide to metal. Table 1 presents the minimum energies which would have to be expended to produce one ton of each of the metals, aluminium, magnesium, titanium and iron from their respective oxides under theoretically ideal conditions at normal temperature and pressure. At higher temperatures, the minimum energy requirements are different, but the values for the various metals still fall in the same order as indicated in Table 1.In actual fact, the energy consumption in the case of any particular metal is higher than the ideal value by an amount which can be determined only by' the results of plant practice. The only general conclusion that can be drawn from the data in Table 1 is that it might eventually prove...

Jan 1, 1950

Mining Systems and Technology - Synchronous Electric Drives for Grinding Mills

Sep 13, 2010

By F. T. Cawood

Inauguration of the new political dispensation in South Africa in1994 initiated a dynamic shift in the ownership, management and development of the country?s affluent mineral heritage. The process of substituting the old South African regime with a new equitable system started soon after the 1994 election of the African National Congress (ANC) to parliament. The Congress?s Freedom Charter revealed the intent of the new dispensation when it called for radical transformation of mineral development. However, since then there have been important changes affecting the rules of mineral development. These are: ?A drastic change in politics ushered in by negotiation, a spirit of reconciliation and a desire to settle disputes peacefully ?The globalization of the South African mining industry in tandem with the opening of domestic mineral resources to foreign capitalists and ?The introduction of sustainable development as a holistic approach to mineral development in order to replace traditional narrow-minded environmental management. Each of these significantly shaped the new mineral investment environment of South Africa. This paper represents a summary of the historical developments leading to the current Mineral and Petroleum Resources Development Act No. 28 of 2002, its regulations, the much publicised Broad-Based Socio-Economic Empowerment Charter, its associated Scorecard, and the Draft Royalty Bill.

Jan 1, 2004

By Kyoosang Yoo

The report presents the results corresponding to the analysis of a lining system for tunnels in soil and soft rock in creep-active ground. The purpose of the analysis is to evaluate the performance of a lining at each construction stage. The steps include: 1. Accurate representation of the initial undisturbed state of stress 2. Excavation, 3. Lining installation 4. Injection of mortar and its curing, and 5. Short-, medium- and long-term creep behaviour in the surrounding soil/rock. The response of a prototype tunnel is simulated using the computational finite element framework MSC.marc2008.

Jan 1, 2010

By Marcus A. Wiley, Gregory Abramov

Borehole mining (BHM) is a remotely operated method of extracting rock material through boreholes by high-pressure water jets. Figure 1 illustrates a BHM tool and fluids circulation. The tool consists of at least two pipes, one for pumping down high-pressure water, the second for delivering slurry to the surface. This article reviews the BHM process. It discusses current and new applications for borehole mining and help the readers determine if BHM is applicable in their situations. Previous articles in ME about BHM explained either a particular project (ME, April 2001, pp. 33-36) or a newest patent in this area (ME, March 1991, pp. 313-318). However, neither one provided an overview on the modern BHM technology.

Jan 1, 2004

By Jewel A. G. Gomes

Green rust (GR) are layered Fe(II)-Fe(III) double hydroxides, having a pyroaurite-type structure consisting of positively charged hydroxide layers and hydrated ions in interlayers. This special feature of GR is very efficient for wastewater treatment as the pollutants are easily taken in or exchanged with the anions in the interlayers. It can be simply and cost-effectively produced by electrocoagulation (EC). Chicken processing plant (CPP) produces large amount of wastewater containing variety of readily biodegradable organic compounds, fats, and proteins. The possible re-use of properly treated CPP wastewater would be economic and environment friendly. In this study, we present our work on treatment of CPP wastewater using EC, specifically for the removal of COD. Analysis of the EC-treated water for reuse in the same plant is discussed considering the U.S.EPA regulations. Two types of EC-reactors were used for this purpose. To better understand the treatment mechanism, EC-floc was also characterized using XRD and SEM-EDS.

Jan 1, 2010

By A. M. Tunstall

Aspects of blast vibrations, damage mechanisms and the influence of rock quality on damage severity are reviewed and results presented from a monitoring programme in which the rock mass rating for six tunnels was determined. The peak particle velocity induced in the tunnels during open-pit blasting was measured and the tunnels were inspected visually for fresh damage after each blast. The results suggest that the quality of rock in which an excavation is situated has an influence on the level of ground vibration to which it can be subjected without sustaining damage. This means that the use of a single limiting value of peak particle velocity, as in the blast damage criteria for residential structures, is not ideal and may result in damage to excavations in poorer-quality rock masses

Jun 19, 1905

By Willie M. NeSmith

Conventional augered, cast-in-place (ACIP) piles were introduced into the New York City area as a result of the damage to existing structures caused by pile driving operations. ACIP piles are often specified where deep foundations are to be installed adjacent to transit facilities, sensitive underground utilities or in close proximity to existing structures. However, loss-of-ground issues associated with the installation of ACIP piles have prevented the wide-scale use of these systems. Beginning in 2002, Berkel & Company Contractors, Inc. began using its augered, cast-in-place displacement (ACIPD) system in the New York City area. Like conventional ACIP piles, this system produces almost no vibration. Also, as almost no material is brought to the surface, there is no opportunity for loss of ground. This paper presents a description of Berkel's displacement pile system and a brief discussion of six projects in the New York City area that have been executed with this system over the past two years.

Jan 1, 2004

By Z. H. Zhou

It is difficult to remove cadmium from raw indium using only electrolytic refining because their standard potentials are similar. In this paper, physical and chemical methods were used to remove Cd from raw indium. Indium metal is vacuum refined for two hours at 400°C with a vacuum pressure of 20 Pa. In this process, 99.70% of the Cd can be removed. The removal rate of Cd reaches 90% to 95% when indium is further smelted for 10 minutes in a 20% glycerin solution of KI and I2 at 180°C. When pre-indium is electrolytic refined in an In2(SO4)3-H2SO4 system, in which the indium content is 80 to 100 g/L, the pH is 2.0-3.0 and the current density is 80 to 100 A/m2, the contents of the impurities decrease and the purity of the indium product reaches 99.99%.

Jan 1, 2007

By R. Falcon, P. den Hoed, A. Luckos, R. Erasmus, V. du Cann, D. Comins

Carbon as a reductant, additive or filler is an essential element in the processing of metallic ores and the manufacture of iron and steel in the metallurgical industry. In most cases, the element carbon is derived from coal and its carbon derivatives. The properties of carbon required for the different processes in each metallurgical sector vary significantly and, for this reason, matching the correct carbon product for each specific process has become an important if not vital function in all sectors of this industry. This selection process, however, has become increasingly difficult. In many cases, the substitution of new products, despite being similar in all relevant chemical specification characteristics to previous products, has resulted in different performance properties relative to that expected. Under these circumstances, the prediction of performance of unknown carbon products has become fraught with difficulties unprecedented in the past. In order to initiate an investigation into addressing these issues, a test case was selected for indepth study the results of which are reported in this paper. The case concerned the use of a specific carbon feed in a conventional submerged arc furnace which gave rise to an unprecedented amount of unreacted or only partially consumed residue trapped in the frozen slag on the refractory walls of the furnace. During the course of these investigations, different advanced analytical technologies were employed including, inter alia, Raman spectroscopy, surface dimensional tests, organic petrology and various thermal reactivity factors. All results have been integrated into a multidisciplinary assessment presented in summary in this paper. Based on the above, and previous experience, the concept of an all-embracing 3-D coal-carbon ?framework? is briefly introduced. This approach has succeeded in obtaining greater depth of knowledge and a better understanding of the issues at stake with specific reference to the organic composition, structure, texture, internal surface area and consequent reactivity of the carbon materials concerned. In consequence, it would now appear that various properties of relevance to the metallurgical industry may be predicted with greater precision than has hitherto fore been possible.

Jan 1, 2004

By Z Chang, S A. Mrozek

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. Antamina, Peru is the largest Cu-Zn skarn deposit in the world. Skarn mineralisation is focused around a multiphase Miocene intrusive complex comprising at least eight distinct phases identified by cross-cutting relationships, including truncated veins, xenoliths and chilled margins. Skarn alteration and mineralisation, as observed in drill core, remain open at depths exceeding 2.2 vertical kilometres.Porphyry intrusions occur as four major phases with subphases (from oldest to youngest): P1 (a, b), P2 (a, b), P3 (a, b) and two dykes of uncertain timing named Oscarina-1 and Oscarina-2. P1a is a hornblende-biotite quartz diorite porphyry with pervasive K-alteration, local endoskarn and 30–40 per cent sheeted quartz veins, all of which obscure original igneous textures. P1b dacite porphyry is a minor unit with <10 per cent phenocrysts and <3 per cent quartz veins. P1b cuts P1a; P2 dykes cut both units. P2a porphyritic biotite quartz monzonite contains K-feldspar megacrysts up to 4 cm long, local K-alteration and 2–80 per cent quartz stockwork veins. P2b biotite monzonite porphyry contains approximately 50 per cent phenocrysts and typically <10 per cent quartz veins. P3a (brown groundmass porphyry) and P3b (coarse phenocryst porphyry) are minor in volume and extent, and both cut P2 bodies. Oscarina dykes comprise two separate but parallel bodies. Oscarina-1 is a feldspar-phyric rhyolite porphyry, while Oscarina-2 is an intensely chloritised andesite porphyry. Oscarina-1 has a U-Pb (laser ablation inductively coupled mass spectrometry (LA-ICP-MS)) age of 10.1 ± 0.1 Ma, whereas P2 U-Pb zircon ages (LA-ICP-MS) range from 10.0 ± 0.2 Ma to 9.9 ± 0.3 Ma.All the intrusive phases contain quartz veins, with P1a and P2a having the most intensive K-alteration and most abundant quartz veins ± endoskarns. Each phase may have contributed to mineralisation at the right depths and within favourable wall rocks (ie marble) during uplift of the Antamina structural block. Therefore, a model of multiple intrusions during continuous uplift explains the vertically extensive (>2.2 km) skarn and mineralisation at Antamina.CITATION:Mrozek, S A, Chang, Z and Meinert, L D, 2015. A model for the intrusive sequence and Cu-Zn skarn formation at the Antamina deposit, Peru , in Proceedings PACRIM 2015 Congress, pp 423–430 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

By G B. Gnoinski

The Skorpion Zinc Mine and Refinery is situated approximately 25 km north of Rosh Pinah, south-western Namibia. The supergene zinc oxide deposit at Skorpion is hosted in a volcano-sedimentary succession within the para-autochthonous Port Nolloth Zone of the Gariep Belt. Rock types hosting the ore deposit include altered and metamorphosed volcaniclastic and clastic sediments, limestone and rhyolite. At Skorpion, the metallurgical process is unique and the plant design requires minimal fluctuations within a selected feed grade. In addition, the presence of limestone inter-fingered with ore in some areas of the deposit results in dilution problems which may increase gangue acid consumption and therefore processing costs. Hence, selective mining is necessary to ensure the delivery of suitable ore to the processing plant, in order to keep the overall operating costs at a minimum. A complex control system is in place and is capable of a high degree of selectivity. The paper describes the grade control system in place at Skorpion Mine which ensures that the qualities of the blocks planned for mining and the material being mined meet the stringent process requirements of the refinery, i.e zinc grade, gangue acid consumption and deleterious elements that may impact on the efficiency and costs of the metallurgical process. Keywords: Skorpion zinc, zinc oxide, supergene, volcano-sedimentary, grade control

Jan 1, 2007

By Mark K. Larson

A constitutive model for rock interfaces based on the principles of static fatigue is proposed. The model is applicable to weak rock or joints with cohesion. Friction and dilation are decreased as plastic work increases. At equilibrium, the creep time increases by one time-step interval, and interface cohesion at each node decreases according to a power function. A constant-load, direct-shear simulation showed that the model is cap- able of mimicking constant-rate and tertiary creep and predicting failure. Tests on core from a coal mine showed constant-rate and, sometimes, tertiary creep, but also weak transitory creep. The cohesion deterioration function may need modification to simulate primary-phase creep. If model parameters are known for a site, the model can predict the onset of tertiary creep and failure. Such predictions can help engineers make better entry design and support decisions, which will reduce the likelihood of roof falls and increase safety for underground miners.

By C. F. Lucks, W. D. Wood, H. W. Deem

Electrical ad thermal-conductivity measurements have been made on titanium and 6 titanium alloys. The following expression was derived for calculating thermal conductivity from electrical conductivity: K = 0.626 s T x 10-8 + 0.00497 where K = thermal conductivity, cal sec-1 cm-2 cm0C-1 s = electrical conductivity, ohm-]cm-1 T = temperature, deg Kelvin This expression gives calculated thermal conductivities that are not in error by more than 10 pct from the experimental values for A-55 titanium and the 6 alloys measured; namely, A-110AT, C-110M, C-130AM, Ti-6A1-4V, Ti-140A, and Ti-155A, which are representative of the presently available commercial a and a-ß titanium alloys. THERMAL conduction in a gas, liquid, or amorphous solid is accomplished by energy diffusion from molecule to molecule, a relatively slow process. For this reason, such materials have a low thermal conductivity. When a material is crystalline, there is in addition a heat transfer by a vibratory motion of the crystal lattice. It is the contribution of this lattice conduction that makes a crystal a much better conductor than a gas, liquid, or amorphous solid. Lattice conduction, however, does not account for the relatively enormous thermal conductivity of a metal. This is explained by the freedom of movement of valence electrons. These valence electrons drift in a metal in a direction toward a drop in electrical potential and, to a lesser degree, in the direction of a temperature drop in the metal. Since both the electrical and thermal conductivities of a metal depend upon the presence of free electrons, there should be some relatively simple relation between the two. Wiedemann and Franz in 1653 first discovered an approximate empirical relation between the electrical and thermal conductivities of metals at the same temperature. This ratio varies appreciably with temperature, and Lorenz later showed that by adding a temperature factor to the Wiedemann-Franz ratio the value of K/(s T) is constant, where K is the thermal conductivity, a the electrical conductivity, and T the absolute temperature. This Lorenz constant shows a greater variation for alloys than it does for pure metals, the ratio increasing slightly as the proportion of alloying elements increases. It has been found that a closer correlation between electrical conductivity and thermal conductivity can be obtained by means of an equation of the form K - A s T + B [1] where A and B are constants. In this equation the term AsT is the contribution of electronic conduction and B is the contribution of lattice conduction to the total thermal conductivity. EXPERIMENTAL MEASUREMENTS Electrical-resistivity and thermal-conductivity measurements on titanium and 6 titanium alloys serve as the basis for determining an equation of the K = AsT + B type for titanium alloys. Specimens—Table I shows nominal compositions of the 7 metals on which electrical and thermal conductivities were measured. The electrical and thermal-conductivity specimens for each alloy were taken from stock of the same heat and usually from adjacent sections of the same bar. All of the metals measured were in a mill-annealed condition. Methods—Electrical-resistivity measurements

Jan 1, 1959

By Robert S. Dewey

AS a result of drilling operations during 1943, West Texas again added sufficient new oil reserves to replace the oil produced during the year, but failed to maintain its position in currently available reserves because the deeper discoveries will require years for development. Drilling failed to provide the additional oil necessary to meet the increase in current and anticipated market demand. Although 13.3 per cent of the total footage drilled was in wildcat exploration, the ratio of oil discoveries to total wildcats was less in 1943 than in 1942, but comparable to that in 1941. Of the 732 field wells completed, 270 were at Slaughter, 55 at Wasson, 45 at Mascho and 31 at North Cowden. As of Dec. 31, 1943, there were 361 drilling wells including 71 wildcat and 290 field wells; 19.7 per cent were wildcats. It is anticipated that the percentage of wildcats of the total wells will be higher during 1944 than in either 1942 or 1943. Tables 3 and 4 present a three-year comparison of drilling activity and illustrate the downward trend of development that has been in effect during that time. Because of development lag in the deeper Ordovician fields, several years elapse before 2 sufficient number of wells is completed to give a substantial producing rate. As these new oil reserves cost more to find, and will cost more to produce on a barrel basis than the oil marketed during the year, their reserve replacement value to the industry is less in money. Costs While complete costs for deeper drilling are not yet available for analysis, it is evi- dent from the data on drilling rates to comparable depths, contract prices, and general increases in costs, that the cost of drilling has risen approximately 20 per cent during the year. One representative drilling contractor estimates that the average drilling time on a 5000-ft. field well has increased nearly one third and that out-of-pocket costs have increased a dollar per foot. Three major factors contribute to this increased cost: (I) less experienced labor, (2) deterioration in mechanical equipment and expendable material, and (3) increased contract prices. In the past, when there were more drilling rigs than wells to be drilled, some contractors would cut their drilling profit to keep their personnel and rigs working. As this practice is no longer necessary, the contract prices are adjusted upward to assure a profit. On deep and difficult drilling, contracts are let on a cost plus basis. A number of mechanical difficulties have become evident. Inferior quality of steel used in drill pipe and rock bits has added appreciably to drilling time and cost. Contractors are experiencing delay in obtaining repair work and repair parts for prime movers. As the length of drilling time required an shallow-field wells has not increased in proportion to that on deeper wells, it seems that the medium-sized drilling rig is better adapted mechanically than the heavy one to the work imposed. One of the main deficiencies in the heavy rig equipment is inadequate pump capacity. Drilling Mud The increasing amount of deep drilling has emphasized the importance and relationship of good mud to efficient and suc-

Jan 1, 1944

By Robert S. Dewey

AS a result of drilling operations during 1943, West Texas again added sufficient new oil reserves to replace the oil produced during the year, but failed to maintain its position in currently available reserves because the deeper discoveries will require years for development. Drilling failed to provide the additional oil necessary to meet the increase in current and anticipated market demand. Although 13.3 per cent of the total footage drilled was in wildcat exploration, the ratio of oil discoveries to total wildcats was less in 1943 than in 1942, but comparable to that in 1941. Of the 732 field wells completed, 270 were at Slaughter, 55 at Wasson, 45 at Mascho and 31 at North Cowden. As of Dec. 31, 1943, there were 361 drilling wells including 71 wildcat and 290 field wells; 19.7 per cent were wildcats. It is anticipated that the percentage of wildcats of the total wells will be higher during 1944 than in either 1942 or 1943. Tables 3 and 4 present a three-year comparison of drilling activity and illustrate the downward trend of development that has been in effect during that time. Because of development lag in the deeper Ordovician fields, several years elapse before 2 sufficient number of wells is completed to give a substantial producing rate. As these new oil reserves cost more to find, and will cost more to produce on a barrel basis than the oil marketed during the year, their reserve replacement value to the industry is less in money. Costs While complete costs for deeper drilling are not yet available for analysis, it is evi- dent from the data on drilling rates to comparable depths, contract prices, and general increases in costs, that the cost of drilling has risen approximately 20 per cent during the year. One representative drilling contractor estimates that the average drilling time on a 5000-ft. field well has increased nearly one third and that out-of-pocket costs have increased a dollar per foot. Three major factors contribute to this increased cost: (I) less experienced labor, (2) deterioration in mechanical equipment and expendable material, and (3) increased contract prices. In the past, when there were more drilling rigs than wells to be drilled, some contractors would cut their drilling profit to keep their personnel and rigs working. As this practice is no longer necessary, the contract prices are adjusted upward to assure a profit. On deep and difficult drilling, contracts are let on a cost plus basis. A number of mechanical difficulties have become evident. Inferior quality of steel used in drill pipe and rock bits has added appreciably to drilling time and cost. Contractors are experiencing delay in obtaining repair work and repair parts for prime movers. As the length of drilling time required an shallow-field wells has not increased in proportion to that on deeper wells, it seems that the medium-sized drilling rig is better adapted mechanically than the heavy one to the work imposed. One of the main deficiencies in the heavy rig equipment is inadequate pump capacity. Drilling Mud The increasing amount of deep drilling has emphasized the importance and relationship of good mud to efficient and suc-

Jan 1, 1944