Search Documents

By W. Y. Xu

In comparison with shallow foundation, usually higher bearing capacity, smaller average settlement and better stability are the engineering characteristics of pile foundation. Besides, a smaller differential settlement and a lower settlement rate which will converge quickly are more important characteristics. The superstructure of the building with pile foundation may not meet with significant differential settlement. In this paper, settlement records and other data of different kinds of buildings are chosen to illustrate the characteristics of pile foundation. Moreover, some technical problems in connection with foundation engineering solved in consideration of the above mentioned characteristics of pile foundation are also introduced.

Jan 1, 2010

By Roberto Chambi

"El presente trabajo señala la expansión de la producción de la mina Condestable a través de las innovaciones tecnológicas en clasificación de molienda como: la utilización de estas zarandas derrick de cinco pisos cada uno, donde se aumenta la capacidad de cada molino instalado en planta en un 17% en promedio, así como el grado concentrado supera el promedio de 26.35%."

Sep 9, 2007

By P. C. Tully

The vapor pressure-temperature relationships for saturated pure liquid nitrogen are calculated by the Strobridge equation using a digital computer. This information is presented in two tables: first) in pressure increments of 0.1 psi from 1.8 to 492.9 psia) and second) in temperature increments of 0.1° from 63.15° to 126.26° K. These tables should facilitate the calibration of temperature-measuring devices over this temperature range.

Jan 1, 1967

By J. G. Ross

IN the paper entitled Block Caving at the King Mine (1), which was presented at the Annual General Meeting held in April, 1934, at Quebec, it was pointed out that, owing to certain conditions and financial restrictions, it was advisable to provide a temporary shaft. This was raised from the )00-ft. level to the bottom of the pit, and a 45-degree incline track was constructed up the face of the pit to surface. The temporary shaft and incline were within the ore-body, but were to be used only until such time as the new shaft-the subject of this paper-could be sunk and made ready for operation. After a careful study had been made of all available information pertaining to the ore-body, including examination of diamond-drill core records and geological data, a shaft location was selected well outside the ore-body. Further, since the crusher and dryer buildings are located over part of the ore-body, it was necessary to plan the removal of these buildings and to construct a new crushing and drying plant. This, and the new shaft, must operate in conjunction with the present mill and rock storage bin, which would continue robe used as formerly. No part of this programme, with the exception of drifting toward the shaft site, was started prior to 1937. More than usual detail on technical features is given in this paper in the hope that some parts of it may be of assistance to other members of the Institute who have to undertake somewhat similar work. The engineering and operating staff designed and supervised the work, while at the same time carrying on regular production in four mines at the rate of 12,000 tons of rock mined per day, the output at the King mine being at the rate of 140 tons per hour. No additional engineers were required.

Jan 1, 1939

Traditionally, capital costs of major resource development projects have been estimated as a single amount to which a percentage accuracy has been assigned based on the method of preparation of the estimate, that is, on the amount of information available to develop the estimate.However, there is a growing recognition of the importance of a probabilistic approach to capital cost estimates, and of a more rigorous calculation of estimate accuracies and of the presentation thereof. Accuracies can be expressed with more certainty as a percentage of the estimate amount where the percentage represents one standard distribution on the probability curve for the capital cost of that specific project. Thus confidence levels can be stated for various estimated amounts - for example, it can be stated that there is an 85% chance that a stated amount will not be exceeded, or a 90% certainty that a (higher) amount will not be exceeded. Moreover, the right skewness of the probability distribution curve for most projects can be readily recognised and reflected in the evaluations. This enables senior executives and board members to have a clearer understanding of investment uncertainties, and the possible magnitude of commitments.

Jan 1, 1990

By Daniel Briones

El presente trabajo señala las bases que fundamentan la aplicación de los Sistemas de Gestión Integrados y se ofrecen argumentos que sustentan los mecanismos usados para integrar los sistemas de Seguridad (NOSA), medio ambiente (ISO 14001) y calidad (ISO 9001); y la necesidad de su uso como herramienta de gestión por parte de la organización, llegando a todos los niveles hasta alcanzar la madurez del Sistema. Asímismo, se describen algunos ejemplos del impacto positivo, que ha significado la implementación de este Sistema en la unidad de producción Uchucchacua (cuarta productora mundial de Plata,), desde el inicio del Proyecto, hasta lograr la revalidación de la Certificación de las normas ISO 14001, y la cercana certificación en OHSAS 18001 e ISO 9001.

Sep 12, 2005

Very little has been written about the discovery and early history of prospecting of ironstone deposits in the Iron Knob-Middleback Range area of South Australia, the main source of supply of ironstone (hematite) for the Australian steel industry, and scanty though the record is, much of it is wrong or misleading.With the help of several people, to whom acknowledgement is made at the end of the paper, the writer has unravelled some of the story, but not the whole story. It is hoped that publication of this paper will stimulate interest in others, who may be able to supplement this account from family records, from the files of newspapers, or from archives.

Jan 1, 1969

By M. Mirnezami, D. Lascelles, J. A. Finch, E. El-Ammouri

"Aggregation, i.e., the tendency of particles to cluster, can be expected to influence flotation selectivity. In this paper, a method of measuring aggregation is introduced and used to conduct plant surveys.Aggregation is measured using settling rate and turbidity converted to an aggregation index (AI) where 0 corresponds to most dispersed and 1 to most aggregated over the range of conditions tested, normally pH. Surveys of Cu and Zn flotation stages at four concentrators showed the AI increased significantly above pH 9. The metal ions identified in the process waters, principally Ca and Mg, were tested to determine which might be responsible. The presence of Mg was found to be the most important. In doping tests, Mg was shown to cause significant variation in AI over the pH range of 9 to 12.The impact of Mg was restricted to pH > 9. Over this pH range, Mg forms a range of hydroxy species, including Mg(OH)2 precipitates. An aggregation mechanism associated with these precipitates, electrostatic bridging, is suggested. Possible problems and opportunities in flotation practice arising from the findings are discussed."

Jan 1, 2002

This backgrounds the methods, and technical terminology, of digital image processing techniques used to write out remote sensing imagery.

Jan 1, 1983

By Hai Lin, Renshu Yang, Yongliang Li, Shizheng Fang

With the aim of solving the large deformation problem of surrounding rock in coal mine roadways with a thin sand-mudstone interbed roof, transportation roadway 1603 in Haoyuan Mine was considered. The failure mechanism of surrounding rock was studied through comprehensive on-site investigations, borehole image analysis, mineral composition analysis, and other means. Numerical simulations were performed to determine the influence of roof layer thickness, lateral pressure coefficient, and coal rib strength on the stability of the interbedded roof. The main reasons for support failure and deformation of the roadway are softening and swelling of the sand-mudstone interbed roof upon exposure to water, insufficient support capacity of the roof due to the soft coal rib, an unreasonable support scheme, or poor construction quality, which can reduce the bearing capacity of surrounding rock. Based on our analysis, a control strategy was devised for a thin coal-mudstone interbed roof. The support scheme combines long and short cable support, strengthening of the coal rib to consolidate the roof, and partially shotcrete grout, and was found to improve the overall mechanical strength of surrounding rock and maintain the stability of the thin sand-mudstone interbed roof. The results of the numerical simulations and monitoring data indicated that the proposed support scheme effectively controls the deformation of the surrounding rock of thin sand-mudstone interbed roof of coal mine roadways while maintaining the safety and stability of the surrounding rock and supporting structure.

Dec 12, 2022

The stability of parallel underground coal mine galleries and pillars have been investigated using two- and three-dimensional (3D) numerical stress analysis. Anisotropic horizontal in situ stresses and the direction of the excavations have been considered in the numerical analysis. The stability of the tunnels driven in a coal seam at various working depths has been investigated taking into account different strata conditions and then results from two- and three-dimensional numerical modelling studies were compared. Maximum principal stress components have been chosen in three various directions: vertical, parallel and perpendicular to the tunnel axis. Analysis have shown that in the anisotropic in situ stress field, the favourable direction of underground mine openings which have different strata conditions depend not only on the horizontal in situ stresses but also on the vertical in situ stresses. Furthermore, 3D numerical modelling studies have been carried out to investigate stability of multiple entry longwall panel gate roads and pillars with various width-to-length ratios (W/L). Results of the modelling studies have shown that the critical dimension of coal pillars depends on their width and the direction of maximum horizontal stresses.

Dec 6, 2010

By H. DeWitt Smith, W. H. Sirdevan

The mine operated by the United Verde Copper Co. is situated near Jerome, Ariz., on the eastern flank of the Black Hills, at an elevation of approximately 5500 ft. (1676 m.) above sea level. The mine and the town of Jerome are located on a steep hillside, which slopes rapidly to the valley of the Verde River. The smelter town of Clarkdale is situated in the Verde valley 4.1 mi. (6.5 km.) distant in an air line from Jerome, and at an elevation of 3560 ft. The two towns are connected by the standard-gage railroad of the Verde Tunnel & Smelter R. R., a subsidiary of the United Verde Copper Co. This road is 11 mi. long and has a compensated 4 per cent. grade. At Clarkdale, it connects with the Verde Valley branch of the Santa Fe R. R. The narrow-gage (36-in.) line of the United Verde & Pacific Ry. was, until 1919, Jerome's only rail connection with a main trunk line. This road connects with a branch line of the Santa Fe system at Jerome Junction, after traversing 26 mi. of mountainous country. From the time of its location, in 1876, until its purchase by Senator W. A. Clark, of Montana, in 1889, the United Verde mine was worked on a small scale and shipments of high-grade gold-silver ore were made from the surface workings. Until 1894, when the narrow-gage railroad to Jerome Junction was completed, all supplies for the mine and smelter

Jan 1, 1922

By Francis D. Leathers

Four friction pile load test programs, including 23 tension tests and 9 compression tests, have been performed as part of the Central Artery/Tunnel Project in Boston, Massachusetts. The tests, performed on both precast, prestressed concrete (PPC) piles and steel piles, yielded the following adhesion values: [Soil Type Clay Clay Glacial Till Interbedded Sand and Clay Interbedded Sand and Clay Pile Type PPC Steel Steel Steel PPC Adhesion (psf) 610 to 1,200 230 to 900 220 to 550 680 1,280 ] The adhesion appears to be affected by differences in pile material type, with PPC piles having higher adhesion than steel piles. However, part of the apparent difference for the clay may be due to differences in time between driving and testing. The significant range of test data means that the need for site specific testing to determine or verify design values of adhesion should be considered during design. Creep rates at loads near failure ranged from about 0.02 to 0.18 inches per log cycle of time, with most values in the range of about 0.04 to 0.08 inches per log cycle of time.

Jan 1, 1994

The new legislative regime applying to the mining industry has been in force for nearly two years. However the parameters for the permits required under the Crown. Minerals Act 1991 and the resource consents required under the Resource Management Act 1991 are still being established. Mining operators will benefit from participating in the development of policies and plans currently being formulated by local authorities. The Energy Legislation Amendment Bill currently before the House contains amendments to the Crown Minerals Act to clarify points of uncertainty and to reduce transaction costs where possible.

Jan 1, 1993

Devitrification of a glassy volcanic ash equivalent to an alkaline trachyte in composition has resulted in the formation of an interstratified illite-montmorillonite with an 1:1\1 content of 1:4 as the principal clay mineral.A high concentration of potassium ions and a deficiency of magnesium ions favoured the formation of the potassium-bentonite.A poorly ordered mica mineral, equivalent to illite, was produced by weathering of potassic feldspar. Subsequent degradation of the illite through the loss of potassium was responsible for the formation of several interstratified minerals with very approximate 1:1\1 contents of 4: I as minor components.Other authigenic minerals present in small amounts were u-cristobalite, sepiolite, and the zeolite clinopitolite.The non-swelling character of the potassium-bentonite makes it economically unattractive...

Jan 1, 1967

A large body of porphyry-type copper mineralization occurs at Panguna in southern BougainviIle. It is associated with the intrusion of quartz diorite/granodiorite into andesites, particularly with the contact zone. Metasomatism of both intrusives and andesite resulted in the formation of biotite pseudomorphing hornblende and the veining of the resultant biotite diorite and biotitized andesite by quartz-chalcopyrite veins with pink orthoclase and dark biotite selvages, respectively.The orientation of intrusives and veins appears to be controlled by premineralization fault-joint patterns in the intruded andesitic Kieta Volcanics.

Jan 1, 1968

A variety of environmental financial assurance instruments are in use across the globe. This paper reviews some of the more common forms currently used in New Zealand, Canada, USA and Australia. In order to be effective, the form of assurance instrument selected needs to be aligned with a countryÆs specific environmental objectives, geography and political climates and also allow for a healthy investment climate. Industry and Government both have a strong interest in ensuring financial assurance criteria meet these objectives.   Recently Golder Associates have been involved in financial assurance assessments for various mining and quarrying companies across the South Island. Multiple stakeholders and regulatory agencies can make the setting of effective and fair financial assurance criteria a complex exercise for both regulatory agencies and industry.  The author relates experience gained in assessing financial assurance under current New Zealand legislation (RMA, 1991), effectively dealing with issues such as ôdouble bondingö and overviews potential approaches to dealing with transitional issues for historic and existing operating mine sites.

Jan 1, 2006

Regions with extensive reserves of brown coal but with inadequate deposits of hard coal provide a particularly suitable field for the application of brown coal petrology.In fact, this discipline is indispensable where brown coal is to form the basis for high-quality products of upgrading. Both chemical and physical analyses are required in addition to the techniques employed in coal petrology, but it is the macropetrographic and the microscopic investigations that are of decisive and specific importance.Foremost among the methods of upgrading brown coal is briquetting. From the raw materials aspect the biochemical rank of coal (i.e. the type of deposit) and the coal variety (i.e. the lithotype) exert a marked influence on briquette strength. These are also the significant factors in the suitability of a brown coal for high temperature carbonization; here the demands on coal quality are even more exacting if adequately sintered and therefore high-strength lump chars are to be obtained. The principle applies also to the char from low temperature carbonization. There are close relationships between the tar yield and the remission of the coal.The reflectivity measurement therefore provides a rapid method for evaluating the suitability of a brown coal for low temperature carbonization. Similar correlations have been established between the content of extraction bitumen (raw montan wax) and the remission. Petrological investigations show that the quality of the coal bitumen is a function of the type of deposit and of the lithotype.

Jan 1, 1968

By Ed Beswick

Resource Update Drilling Program ? Pre-feasibility ? Exploration Metallurgy Program ? Grindability ? Metallurgical Optimization ? Hydrometallurgical Options Preliminary Mine Development Design Environmental Permitting Infrastructure Development

May 1, 2008

By T. Salman

Most authorities agree that the dissolution of gold from an ore takes place according to the Elsner equation first stated in 1846. The main requirements for the dissolution reaction to proceed are:(1) that the gold be clean.(2) that the gold be exposed to the solution.(3) that the cyanide solution be active, i.e., not over loaded with impurities which could retard or inhibit the reaction.(4) that an adequate supply of oxygen be available (from air).When the above conditions are met, cyanidation becomes basically a mechanical operation.Minerals such as quartz, calcium carbonate are relatively inert to cyanide though they may give rise to mechanical troubles. Most ores present an assortment of chemical problems, depending upon the constituent present, which react to the solution to varying degrees. It should be borne in mind that minerals which are disturbing to the operation, though present in small amounts, usually exceed the weight of the gold by several hundred times. In addition, the application of flotation and other forms of concentration to gold ores, previous to cyanidation, concentrates not only the gold, but also the other heavy minerals and these complicate the chemistry of the process.

Jan 1, 1975