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By Enrique Sigarróstegui

Hace quince años la mina Quiruvilca utilizó los pernos de roca diseño mariposa como uno de los elementos para el sostenimiento de la roca. Sin embargo, su uso fue descontinuado y se tuvo que usar un perno de otro tipo de diseño mariposa, luego de haber evaluado la calidad de su anclamiento en la roca. En este sentido, el objetivo del texto describe la selección de un tipo de mariposa en los pernos de roca que ofrezca una mejor capacidad de anclamiento con un alto coeficiente de seguridad, así como se refiere un estudio detallado de sus alternativas.

Oct 14, 1980

Mine Terex articulated dump trucks are working on a large restoration project of an abandoned open cast coal site in Blacklaw, central Scotland. The project is part of the construction of a 42-turbine wind farm complex. During the scheduled 18-month duration of the project, three 28-t(31-st) Generation 7 TA30 dump trucks and the six 36.5-t (40-st) TA40articulated trucks are estimated to move about 1Mm3 (1.3 million cu yd)of material. The trucks are working12-hour shifts, 5.5days a week.

Jan 1, 2005

By E. J. Wasp

An upsurge of interest in slurry pipelines to move coal from Wyoming, Montana, and Colorado to markets in the southwest, west, midwest and northwest has recently developed. Specific pipelines have been proposed to serve these markets; the routes of these lines are depicted in Exhibit I. It is, therefore, timely to discuss some technical aspects of the terminal facilities for these western coal pipelines. The discussion will be based on experience with the Ohio and Black Mesa pipelines as well as detailed planning and testing for a proposed 1,000-mile system from Wyoming to the middle south area. The economics of the pipeline terminal processes are heavily depend¬ent on site, type of process used, and other specifics of the situation. However, the following approximate breakdown of costs for a 1,000 mile, large capacity pipeline will be useful for orientation purposes. [Water supply 4 Coal cleaning 5 Feed preparation 10 Slurry transportation 72 Dewatering terminal 9 100%]

Jan 1, 1976

Termination of membership In accordance with By-Law 7.6.1. of the Constitution of the Institute, the names of the undermentioned members have been removed from the membership register. Colloquium and General Meeting A General Meeting and Colloquium on 'Heavy-medium separation and ore sorting' was held on 18th September, 1974, at 09h15, in Kelvin House, Johannesburg.

Jan 12, 1975

By Greg Canivan, Bernie Hertlein, Les Chernauskas, Joram Amir, Garland Likins, E. Anna Sellountou, Tim Kovacs, Peter Kandaris

Nondestructive testing of drilled shaft foundations via Crosshole Sonic Logging (CSL) is often performed as part of the quality assurance process to assess the soundness of concrete. The intent of CSL testing is to identify irregularities such as soil intrusion, necking, soft bottom, segregation, voids and other defects that could result in poor structural performance of the foundation. Over time, CSL rating criteria based on first arrival time and relative energy have incorrectly evolved to often be the sole means of determining the acceptability of a shaft. Some of these criteria have found their way into regulatory agency specifications, with acceptance values often differing from agency to agency.The purpose of this document is to review the state of the practice (including experience gained over the past 20 years), propose improved CSL rating criteria and make recommendations for additional assessment, as well as educate the industry on the proper interpretation of CSL test. CSL test results alone should not be the sole means of rejecting or accepting a shaft. A task force of industry exerts was formed to review the existing CSL rating criteria and propose improvements where appropriate. The recommendations presented herein are the consensus of the task force, which believes that they should be incorporated into future criteria, codes and specifications. This paper was produced as a joint effort between the Codes and Standards Committee, the Drilled Shafts Committee and Testing and Evaluation Committee. A task force was authorized under Testing and Evaluation Committee. The task force contributed their expertise in web-based discussions often every two weeks over a period of three years. Interested participants were invited to participate at any time. The document had two rounds of broad industry review, two rounds of DFI Technical Advisory Committee reviews, and a Public Comments process. All comments were considered in producing the final document.

Jan 1, 2019

By E. H. Roberts, L. G. Swenson, F. C. Nix, R. A. Morgen

THE binary system lead-antimony has been the subject of comprehensive investigations in these laboratories by Dean' and his associates. The effect of a third constituent on this system, particularly on the lead-rich alloys in which dispersion hardening was found, has a commercial value as well as an academic interest. This paper covers the effect of the addition of copper, bismuth and tin, all of which are likely to be found in commercial lead-antimony alloys, and is divided into three parts, as follows: I. The System Lead-Antimony-Copper II. The System Lead-Antimony-Bismuth III. The Lead Corner of the System Lead-Antimony-Tin These three systems are of three different types, and hence may be considered as covering three general kinds of additions. Bismuth forms no compounds with either lead or antimony and forms solid solutions with both. Copper forms several compounds with antimony as well as solid solutions but with lead it forms a two liquid layer system and no appreciable solid solution. Tin is soluble in both lead and antimony in the solid state and also forms a compound with antimony. The effect of small amounts of bismuth on the lead-antimony alloys is small, having no appreciable effect on the solubility of antimony. The temperature of the solidus floor is lowered appreciably by the presence of bismuth, cutting down the range of heat treatment. Copper, on the other hand, due to compound formation, increases the apparent solubility of antimony. The excess antimony is tied up with the copper finally and so is not available for dispersion hardening. The net result of addition of small amounts of copper is to shift the dispersion hardening peak of the

Jan 1, 1928

By Raúl Daniel López

Ternium-Siderar steelmaking has been focused in permanent improvements and process optimization. At present the Slab Continuous Caster N°1 has been totally transformed after 20 years of uninterrupted work. The authors of this paper summarize and comment on aspects which were the main changes and place emphasis largely on those technological developments in which they have been active during that period. Productivity and quality have been our goals during the last 20 years; it has led us to improve process and to achieve better control tools. In the development of this presentation, the authors will put special emphasis on the explanation of those works that were made following their own experiences through the technical personnel who belong to the staff of the company.

Jul 30, 2018

By A C. Carter

The increasing need for alternative energy sources as well as the less clearly perceived but equally increasing demand for non-fuel minerals has resulted in extensive exploitation of near surface deposits. Many such deposits have depleted reserves and mining corporations are increasingly turning their attention to deposits, with thicker overburden, less competent materials, steeper dips and more complex structure. These deposits pose mine layout, geotechnical and equipment problems as well as the need for large outputs to achieve economies of scale. The paper describes the major problems and operational solutions for such deposits using continuous excavation and transport equipment.

Jan 1, 1980

By Ike Isagon

Outline 1.Background Sudbury Backfill Operations 2.Alternative Binder 3.Alternative Binder Trial Process Flow Diagram ?Laboratory Results ?Plant Trial ?Final Evaluation and Approval ?Management of Change (MOC) 4.Economics 5.Conclusion 6.References and Acknowledgements

Nov 1, 2011

By KenGemar P, Perembo R. C B, Winn R. D

The New Guinea orogen comprises terranes that have accreted to the northern margin of the Australian craton. The history of the accretion of terranes begins earlier (in the Late Cretaceous) and is more complex than has been suggested previously. There was a collision in the central highlands in the Late Paleocene or Early Eocene, and a Finisterre collision that precedes and is distinct from the later (Pliocene) Bismarck volcanic arc collision.

Jan 1, 1997

The movements of the major continental cratons and the distribution of the principal tectonostratigraphic terranes are reviewed in the Circum-Pacific region during Phanerozoic time. It is concluded that major periods of orogeny and consolidation of accreted terranes in the Circum-Pacific region is best correlated with periods of advance of cratonic blocks over the Pacific Ocean basin combined with relative convergent to transpressive motions between the cratons and the Pacific Ocean plates. Continental collisions and collision of terranes with continental margins has not been a significant geodynamic process in Circum-Pacific tectonic evolution. The permanency of the Pacific Ocean basin throughout 500 MA is remarkable. It appears no continental block or large continental fragment has ever entered or crossed the Pacific Ocean basin since early Paleozoic time. This area where no continent has entered for 500 MA is almost coincident with the present Pacific Ocean basin and seems associated with the 25 to 100 meter geoid high which dominates the present-day figure of the Earth.

Jan 1, 1990

By T H. Clark, R P. Doig, V. A. Saull, R B. Butler

Terrestrial heat flow has been determined for four boreholes in the Montreal area. The mean value of the results (uncorrected for glacial effects) is 0.790 ± 0.053 x 10-6 cal/ cm2/sec (95 per cent confidence limits). Thermal gradients were determined using a thermistor probe and d-c bridge, and also by a new method using a probe-contained phase-shift oscillator, the output frequency of the oscillator being a function of probe temperature. Thermal conductivity determinations were made on core from the boreholes, using a divided bar apparatus. INTRODUCTION T HIS paper concerns the terrestrial heat flow in the St. Lawrence lowland of Quebec, as determined from measurements on four of the numerous boreholes drilled in this region for gas and oil. The work has been supported by Geological Survey of Canada Re-search Grant 3-58, awarded to T. H. Clark and V. A. Saull. This sup-port is hereby gratefully acknowledged.

Jan 1, 1962

By Julian Malnic

Transplanting the steps used in exploring and developing mineral deposits on land into the marine environment will help developers. While familiar to oil and gas explorers and many other sea-based industries, the marine environment is so alien to the 90s terrestrial miner that the phrase ?terrestrial mines in the sea? is useful for reinforcing the fundamental parallels in mining sulphides at sea and on land. As on land, the processes of ?pre-feasibility study? and ?feasibility study? will determine the economics of mining a deposit. For many, the step into the sea can detract from the need to follow these familiar and recognised steps used when any new deposit is found on land. The technology to mine sulphides in the 1500 to 2000 m depth range exists. Currently, it is not found in a single, integrated and commercially available system but every element available to build such as system is. Transplanting the thinking of the leaders of the terrestrial mining industry into the sea will perhaps be the greatest challenge and reinforcing the basic steps of discovery - pre-feasibility through to feasibility is the best way to achieve this. After all on land one doesn?t ask ?Can we profitably mine it?? before one can authoritatively answer ?What have we found??. Research by Nautilus Minerals Corporation suggests that the mining of seafloor massive sulphides (SMS) will not only be profitable but potentially lower in both capital and operating costs than prevail in most terrestrial deposits. Nautilus is also acutely aware that with the first SMS deposits under title, it will be setting the standards for seafloor mining into the new millenium. Indeed, we have trained on us not only the eyes of the mining industry waiting to see if SMS deposits really do offer radically better returns, but other stakeholders of the sea and the capital markets. Mistakes by any SMS developer could land all developers in ?hot water?. The rush to exploit our deposits for economic gain will be tempered by ensuring there is adequate public debate and consultation for our environmental code. Failure in any facet of a marine mining development could set back the move to the ocean floor.

Jan 1, 1998

By A. Dale Wunderlich

Since Sept. 11, 2001, the author has been asked by several mining companies and mining publications to share some of his insights on how the terrorist attacks on the World Trade Center (WTC) and Pentagon might affect the mining industry globally. Until now, the author has been reluctant to express his thoughts in a publication that could possibly fall into the hands of terrorists and give them some ideas that they may not have been previously considering. However, the author discussed the contents of this article with several friends and acquaintances in the international intelligence community. They said that nothing commented on here is new to the terrorists. Potential terrorist targets Sources within the worldwide intelligence gathering community have told the author that current intelligence data indicates that it is likely that the Islamic fundamentalist groups responsible for the attacks on Sept. 11, 2001will likely be directing their effort at foreign business entities. Any overseas or any domestic businesses of highly visible companies that are part of the anti-terrorism alliance should consider themselves a potential target.

Jan 1, 2002

In addressing the need for non-degree tertiary training, let us examine some recent reviews of engineering and geoscience education. The Finniston Report (1) criticised the formation of engineers in the UK and stated that this was largely due to the narrow British conception of engineering as a branch of applied science which militates against an effective marriage between theory and application. It also criticised the system for not giving students sufficient grounding in the synthesis of technical, human and financial considerations within their undergraduate courses. As we all know, this report has led to the restructuring of engineering education in the UK. More recently, a Review of the Discipline of Engineering was carried out in Australia by a committee chaired by Professor Sir Bruce Williams (2). The report stated that: Australia has a fairly good system of engineering education that should be made better. more should be done to develop the communication skills of both staff and students. more attention should be paid to changes in engineering practice and the human element in technology. there is a serious shortage of state of the art equipment in most engineering schools. female enrolments in engineering courses should be increased from the current level of about 7% to 20% by 1997. employers should develop a better understanding of the need for continuing education. staff in engineering schools should develop closer relations with employers of engineers. higher education institutions with engineering schools should give financial and other inducements to staff to increase the proportion of study leave or professional development leave spent working as engineers in the business sector. there is considerable room for improvements in the teaching process and in the development of evaluation schemes for assessing the teaching contributions of staff. In its recent report to the Council of the Institution of Engineers, Australia, the Task Force on Engineering Education(3) makes the following points: managerial, entrepreneurial, professional and interpersonal skills should be introduced and integrated into the undergraduate courses but studied in depth as part of continuing education. the continuing education policy of the Institution should be promoted and strengthened with all engineers required to pursue continuing education. the Institution should develop a comprehensive guide to continuing education available from universities, colleges and other public and private sector organisations.

Jan 1, 1989

By Y. Chengxian

Many factors about the HIC (hydrogen-induced cracking) resistance of pipelines are discussed in this paper. The main factors that influence the ability of HIC are environmental and material factors. The chemical compositions, non-metal inclusions and microstructure are discussed in detail, while a group of tests on HIC resistance are done according to varying C, S, Mn and P contents in pipeline steels, different experiment time and different strength to the coupon. It is concluded that decreasing the amount of C and S can obtain good HIC resistance; the test time has an effect on the different microstructure of X70; microstructure is the most sensitive factor for the initiation processes of HIC.

Jan 1, 2005

By Y. Chengxian, F. Yaorong, Xinzhe. L.

Many factors about the HIC (hydrogen-induced cracking) resistance of pipelines are discussed in this paper. The main factors that influence the ability of HIC are environmental and material factors. The chemical compositions, non-metal inclusions and microstructure are discussed in detail, while a group of tests on HIC resistance are done according to varying C, S, Mn and P contents in pipeline steels, different experiment time and different strength to the coupon. It is concluded that decreasing the amount of C and S can obtain good HIC resistance; the test time has an effect on the different microstructure of X70; microstructure is the most sensitive factor for the initiation processes of HIC.

Jan 1, 2005

By Baxter C. Madden

Stress corrosion is defined and certain examples are illustrated. A number of test methods, to determine the resistance of materials to stress corrosion, are being developed at Wright Field. The criterion as to the validity of a method is stated. Three types of specimens and the method of stressing each type are described. Five different corrosive conditions are set forth. The results of tests to date, although too few for any general conclusions to be arrived at, are presented. The program for the continuation of the investigation is indicated. A bibliography is included. The development of the method of loading a cantilever-type specimen, so that a nearly constant stress at a large deflection may be realized, is presented as Appendix I.

Jan 1, 1945

By Borje Bjorkvall

At LKAB's plants in Lappland, Sweden, sintered pellets are manu-factured according to three different industrial processes, viz. shaft furnace at Malmberget, straight-grate at Kiruna and grate-kiln at Svappavaara. At present the total annual capacity amounts to 4.7 million tons. However, since it has been decided to erect a new straight-grate plant (2.5 million tons) at Malmberget, and because of the decision to extend and rebuild the existing plants, it is estimated that the annual capacity will be increased to somewhat over 8 million tons by 1973. The great majority of the pellets produced is exported. They are thus reloaded several times and generally speaking roughly handled, resulting in larger or smaller product losses on arrival at the point of use. It is there-fore of great economical interest to have a good control over the transport strength of the pellets by appropriate quality testing at the point of production. In addition to good transport strength, further demands are ob-viously made on pellets destined for blast furnace operation. The blast furnace burden must maintain a good permeability for the gas. The pellets must thus have a favourable size distribution and must not be so weakened by reduction that they disintegrate under the stresses and clog the blast furnace shaft. Furthermore, the burden must have good reducibility. An increase of the rate of reduction can obviously mean increased blast furnace capacity and reduced coke consumption. In order to optimise the properties of the pellets in these respects, the producer must also be thoroughly familiar with their behaviour during reduction, particularly as the customer's interest in the reduction properties of the pellets' has increased over the last few years. Up to now the only quality demands the customer has made have generally had to do with the cold strength and the screen analysis. Thus a quality control of in addition to good transport strength, further demands are obviously made on pellets destined for blast furnace operation. The blast furnace burden must maintain a good permeability for the gas. The pellets must thus have a favourable size distribution and must not be so weakened by reduction that they disintegrate under the stresses and clog the blast furnace shaft. Furthermore, the burden must have good reducibility. An increase of the rate of reduction can obviously mean increased blast furnace capacity and reduced coke consumption. In order to optimise the properties of the pellets in these respects, the producer must also be thoroughly familiar with their behaviour during reduction, particularly as the customer's interest in the reduction properties of the pellets' has increased over the last few years. Up to now the only quality demands the customer has made have generally had to do with the cold strength and the screen analysis. Thus a quality control of

Jan 1, 1972

By Gunnar Thaning, Borje Bjorkvall

At LKAB Central Division for Metallurgical Research at Malmberget, Sweden, fired pellets are examined in respect to mechanical and reduction properties. The paper deals with descriptions of the test methods. It also involves the rationale for the choice of these tests. Their correlation to the blast furnace operation will be examined. The mechanical tests used are the ISO-tumbler test and the cold compression strength test. Concerning the metallurgical properties, experiments have shown that some superbasic pellets in particular have different disintegration properties in different temperature ranges. Pellets which have favorable reduction properties when tested under isothermal reduction at high temperature may disintegrate to a large extent under low temperature reduction. This is also valid for some types of acid pellets. Consequently, it was found to be necessary to determine the reduction strength both at high and low temperatures. In the low temperature range, the disintegration is measured by tumbling the pellets in soft reducing conditions at 600°C in a modified Linder test equipment. The high temperature reduction strength is determined under load in the Burghardt-Grebe equipment. However, in order to get more information of the high temperature strength, LKAB intends to introduce a softening test. The tendency of high temperature disintegration will also turn up in the swelling test. The swelling properties are examined according to a procedure developed at LKAB. In this test the pellets are subjected to free swelling without mutual contact. The reducibility of the pellets is recorded in the swelling test.

Jan 1, 1974