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By Zhiqiang Zhou, Shengnan Zhou, Zizong Zhu, Yuchuan Ding

The effect of silicon on removal of phosphorus from high phosphorus Si–Mn alloy was investigated at 1673 K by CaO-based slag. It was found that the dephosphorization efficiency increases significantly as increasing the silicon content, which is due to the reaction between silicon and CaO at slag/alloy interface. The relation between silicon content with oxygen activity and phosphorus activity coefficient of Si–Mn melt was determined respectively as follows: lg aO = -1:55xSi - 1:67; ln rP = 9:26e xSi 0:0433 + 11:0839 The carbon content in Si–Mn melt decreases continuously with the increasing silicon content, meanwhile, the decreasing rate of carbon content becomes rapid when the mole fraction of silicon is about 0.32. Si addition is beneficial for both dephosphorization process and low carbon Si–Mn alloy production.

Mar 1, 2017

By M. H. Moys, J. Engelbrecht, N. Terblanche

Interface levels in flotation columns are generally measured with the aid of a pressure-sensitive Instrument, e.g. a differential-pressure cell. This paper criticizes the use of this type of measurement, and discusses other methods that are claimed to give more accurate measures of interface levels. The paper focuses on the development of methods based on the measurement of conductivity across the froth-slurry interface. These are often sabotaged by variations in the conductivity of the feed slurry, particularly when the pH of the slurry IS being controlled, e.g. In sulphide flotation. Methods of improving the accuracy and reliability of this technique are described. The result IS a robust, easy-to maintain level-control scheme that successfully rejects large disturbances in plant operation (including a 5:1 change in slurry conductivity) while controlling levels to an accuracy of I 4 cm.

Jan 1, 1992

By Thomas T., Read

IN this survey of the progressive development (of education for the mineral industries throughout the United States, the review of .the history of each school has usually been completed wherever it is first mentioned, but the history of the schools in the cities of the eastern seaboard was not carried beyond 1870. It is necessary now to cover what happened during the period of approximately the last quarter of the nineteenth century in several of the schools in the east. Philadelphia Of Philadelphia, it has been related in chapter 4 that the Polytechnic College of Pennsylvania began offering a curriculum leading to the B.S. in mining in 1853; that the school did not prosper, and finally closed about 1890. The establishment of a Department of Mining, Arts, and Manufactures at the University of Pennsylvania in 1855-56 was also mentioned, but its history was not carried beyond 1860. In 1859 J. Peter Lesley was appointed professor of mining in the University of Pennsylvania. The son of a cabinetmaker, born in Philadelphia Sept. 17, 1819, he had taken his A.B. degree at the University of Pennsylvania in 1838 and then secured a position on the Geological Survey of Pennsylvania under H. D. Rogers. When the Survey was discontinued, in 1841, he went to Princeton to study theology, was ordained a Presbyterian minister and followed that career until 1852, when the Pennsylvania, Geological Survey was again started and he rejoined its staff. He published "A Manual of Coal and its Topography" in 1856, and studied at the École des Mines, Paris, in 1856-57. He published an 800-page "Iron Manufactures Guide" the year that he was appointed to the staff at the University of Pennsylvania. In 1863-64 a College of Agriculture, Mines, Arts and the Mechanic Arts was established, but it was not a separate school

Jan 1, 1941

By Karsten Beckhaus

Barrier walls in levees and dams are designed and constructed for new structures and for rehabilitation or upgrade of existing structures to control seepage. Construction methods applied are often deep soil mixing with a cementitious slurry or excavating a trench and refilling it with a plastic concrete. This paper explains the technical background of jointless cementitious barrier walls inevitably developing thermal tensile stresses and how these stresses can be controlled. The theoretical background of thermal stresses is explained based on experimental and numerical studies of essential factors. Although a low cracking risk is generally inherent, risk mitigation measures should be taken to thermal cracking and to ensure the permanent function of such walls as a low-permeability and high-deformability barriers.

Sep 8, 2021

By R. L. Grayson

In 1995, Congress abolished the Bureau of Mines in the Department of Interior but preserved the safety and health research functions being performed at the Pittsburgh and Spokane Research Centers. These functions were transitionally housed in the Department of Energy before permanently merging with the National Institute for Occupational Safety and Health (NIOSH), Department of Health and Human Services, in October 1996. Since the merger of the former Bureau with NIOSH, there has been an active evaluation of ongoing research activities, significant interaction with stakeholders, and the development of a process leading to "data informed" priority setting. This presentation will review current surveillance information concerning the level of injury and disease from mining work and will discuss how research priorities are evolving to improve the contribution of research to the prevention of injury and disease.

Jan 1, 1998

By Allan G. Provost

Shaft construction is assuming ever increasing importance when new mining enterprises are considered. The reasons for this increased emphasis is the much greater depths at which many new ore-bodies are being developed and the rapid depletion of near surface reserves requiring mines to go to greater depths on existing deposits. These greater depths increase the probability of exposure to unfavorable geologic conditions and it is more likely that high ground and/or water pressures will be experienced at these depths. The large capital costs involved and the critical position of a shaft in the overall mining program necessitate that this element of project development be given careful and critical consideration. The Henderson No. 2 Shaft is located in the Rocky Mountains of north central Colorado (See Figure I), about 55 miles west of Denver, near the community of Empire in Clear Creek County. At the 10, 442 foot collar elevation, winter arrives in late September and brings snow to contend with until May. The labor force for Shaft No. 2 is approximately 90 men. They are provided access to the project via all-weather U. S. Highway 40. SHAFT DESIGN The Henderson No. 2 Shaft is a 28-foot I. D. circular, concrete lined (1 foot thick) vertical shaft. The final depth will be approximately 3100 feet

Jan 1, 1972

By Stephen Darmawan, Mahdi M. Disfani, Arul Arulrajah, Alireza Mohammadinia

Deep mixing using cementitious compounds is an in-situ method of ground improvement for improving the strength, compressibility of loose sand. Artificial light cementation can increase the stiffness of loose sands significantly and reduce the settlement of loose deposits. The increase in contact area between the particles with a thin layer of cementitious agent depends on the confinement and void ratio of the soil mass. Hence, the stiffening effect of cementation not only depends on the type and amount of cementing agent and inter-particular force chain of loose deposit but also depends on the stress level at the time of cementation. In addition, the cementation effect in loose deposits can be deteriorated at relatively low strain levels. Decementation softening can cause detrimental and irreversible impacts on the soil deposit. This study investigates the effect of initial confinement and subsequently the initial void ratio at the time of cementation on small strain behaviour and decementation softening of cemented loose sand under ko loading. The effect of inter-particular contact of sand particles based on the specific surface area and also soil density was also investigated by means of shear wave propagation. This study present insightful information on effect of primary consolidation stress levels, density of soil and cementation level on softening and collapse of loose deposits improved using deep soil mixing technique. Better understanding of soil-cement interaction by optimization of binder content for deep mixing activation can lead to increasing the level of confidence in using this technique in ground improvement applications.

Jan 1, 1900

By Harry R. Nicholls

As part of the pre- and post - shot mine examination at Project GNOME , acceleration data were recorded underground from a series of chemical explosive shots . The cube root of the charge weight was used to scale acceleration and distance because charge weight was not constant . Regression analysis of particle acceleration - distance data gave the following propagation equation : A W1 /3 = 5.10 x 105 ( R / W¹ / 3 ) −2 .43 The quantity A W1 /3 is scaled particle acceleration expressed in g's - lbs¹ / 3 , and R/W1 /3 is scaled distance expressed in ft / lbs¹ /3 Data obtained from the nuclear explosion were scaled and fall within one standard deviation of the calculated propagation law for the smaller shots . Cube root scaling laws were adequate to group acceleration data from explosive charges varying by a factor of more than 1 x 10 in charge weight and over shot - to - gage distances varying from 100 to 46,000 feet . Data obtained from a series of small tests provided sufficient data from which reliable predictions of acceleration could be made for the large nuclear explosion .

Jan 1, 1964

By Phil Jones

"Dilution — planned and unplanned – remains a significant cost impairment in the mining process. A series of trials were held over a sixmonth period in fiscal year 2018 (FY18) that established the cost-benefit of new technology as it applies to the alignment accuracy of production drilling rigs in underground mining, thus confirming its ability to limit drilling as one of the causes of dilution. The trials identified three underlying factors affecting drilling accuracy, measurable by blast-hole deviation surveys of planned versus actual toe data. These were rig alignment error, collar location change/ error and in-hole deviation.The trials involved a comparison of existing rig setup processes and technology, with the new technology (Minnovare’s Production Optimizer system). The trials were undertaken in the same environment: the Cracow gold mine, an operating underground mine. The comparison first revealed the extent to which rig alignment impacts blast-hole deviation. Secondly, the new technology was proven to limit rig alignment error, thereby reducing average blast-hole deviation and increasing the number of holes drilled within tolerance by 160 percent.The increased accuracy reduced stope dilution by reducing over-break of subgrade ore. The new technology was implemented at Cracow during the latter half of 2018. Despite utilizing the new technology for just six months of the year, the mine recorded a 5 percent overall reduction in dilution for the full year compared to the previous year (FY17); from 22 percent down to 17 percent (a net decrease of 22.7 percent). Mine management attribute a significant proportion of this reduction to the new technology, along with sequencing and planning improvements. This opinion is backed by detailed stope reconciliation data taken during the trial from 28 stopes — representing 20 percent of the total tonnes mined during FY18. The data identified that stopes drilled using the new technology recorded 62.6 percent less average dilution."

May 1, 2019

By J. Galloway, P. K. Hofmeyr

Obviously all mining operations require much analytical work to be carried out. This starts with exploration, becomes more stringent with the evaluation of a mineralised area and finally becomes on-going when mining operations are under way. All these phases are carried out by geologists, metallurgists and mining engineers. They require analyses to carry out their functions but usually have no involvement in the analyses themselves. Analyses are carried out at commercial laboratories or in-house analytical laboratories. In the past in South Africa the tendency was for the larger mining houses to have their own centralised laboratories for exploration samples with each mine having it?s own laboratory to meet only that mine?s requirements. The centralised laboratory maintains QC functions at the subsidiary laboratories. In other mining areas of the world there has been a strong tendency for all geological analytical requirements, especially for exploration and mining, to be carried out at commercial analytical laboratories. In recent years there has been a tendency for mines in South Africa to move in the same direction. This paper discusses the factors that need to be taken into consideration when a new laboratory is being planned and automation is an option. The planning of the laboratory at the new Langer Heinrich Uranium mine in Namibia is discussed considering these factors. 2.0 REQUIREMENTS OF A MINING ANALYTICAL LABORATORY The purpose and requirements of a mining analytical laboratory are fairly obvious and can be summarised as follows :- 1. All mining operations must have access to analytical facilities, either in-house or commercial 2. The laboratory must be able to handle all the sample types submitted by the mining operation These can be mining, exploration and/or plant samples. They can comprise solids (rocks, bore-cores), slurries and/or liquids.

Jan 1, 2007

By R. T. Dec

A review is undertaken of existing mathematical models of compaction process in roll press. The example of plane-strain, plane-stress model is presented together with comparisons between computed and experimentally recorded pressure distribution in roll nip region. Next, the discrepancies between predicted and measured values are discussed and practical method based on experimental optimization of compaction process using laboratory roll press is proposed. Examples of the selection of optimum roll press operating parameters for calcium oxide fines, sodium chloride and iron oxide dust are presented to illustrate advantages of the method. Finally scale up procedure is discussed for estimating the performance of commercial size roll press based on the data collected on laboratory size equipment.

Jan 1, 2000

By N. Bédard

"This paper highlights Cambior’s initial approach for recruiting and retaining its international employees, the importance of proper preparation and the support needed to ensure a competent and stable workforce.In general, most of the training and information available for human resources personnel prepares the specialist for handling various aspects of labour relations, recruitment and hiring, benefits administration, employee relocation, etc. This is usually done in a Canadian context.Only recently, has more specialized training been developed to prepare human resources practitioners for the complex issues related to expatriate employees and dealing with human resources issues in other countries"

Jan 1, 2004

By C. H. Bucknam

Classical acid-base accounting using modified Sobek titration methods has resulted in interpretation of results for materials with neutralization potential (NP) less than 20 tons of CaCO3/1000 tons of material (2% CaCO3) as "uncertain" due to lack of sensitivity within that content range. Standardization of a "fizzless" acid neutralization potential (ANP) method was undertaken in the American Society for Testing and Materials (ASTM) International using two ranges of sulfuric acid additions based on reaction pH and carbonate carbon estimates rather than subjective fizz testing as well as hydrogen peroxide additions to correct for mineral acidity. The method is identified as the acid neutralization potential acidity (ANPA) titration method. During interlaboratory testing a positive bias was discovered within the "uncertain" range which was further investigated and resolved by increasing the test sample weight from one to five grams for samples needing improved accuracy in materials with ANP <2% CaCO3. Test results from the interlaboratory testing of the low range method is presented and compared with the results from the original ANPA method in the paper.

Feb 27, 2013

By Stephan A. Jefferis, Adrian H. Bath

"This paper draws together some themes on the durability of barrier systems, and particularly cementitious systems. For contaminated land and water retaining structures, durability can be poorly addressed at all stages of a project, from specification, to barrier material selection, barrier design including toe-in and through to performance assessment in operation. Permeability (hydraulic conductivity) is a dynamic property which will vary over time as reaction processes propagate through a barrier. However, laboratory testing, when undertaken, tends to be focused on short term tests with aggressive chemicals so that the effects of longer-term processes such as carbonation and leaching by permeating water are missed. For water retaining structures, carbonation and leaching actually may be the most significant processes affecting barrier performance as the groundwater adjacent to many water bodies can be otherwise rather benign (as regards bentonite and cementitious systems). These and other reaction processes have been modelled in the arena of nuclear waste repositories and procedures are well recognised. However, such procedures have yet to be widely adopted for the assessment of other barrier systems.INTRODUCTIONOver the last few decades there has been an enormous amount of laboratory research on the durability of barrier materials or more specifically papers reporting the results of permeability tests. Unfortunately there is a much smaller literature on scaling test results to barrier dimensions in the field or to required design lives. Although in the geotechnical industry durability research has been largely laboratory based, in the nuclear industry where relevant timescales are multi-millennia rather than decades, research has been heavily underpinned by geochemical modelling. A significant purpose of this paper is to examine the tools that may be used to analyse the results of tests on barrier materials used in geotechnical engineering, for example, for water retaining structures and contaminated land and draw the attention of the construction industry to the potential of the modelling procedures developed for nuclear repository assessments. Modelling can help to identify underlying processes and so augment information from laboratory testing focused on changes of physical properties such as permeability and strength."

Jan 1, 2016

By J. VAN DEN BERC

Tin production and export from the Far East are still a long way off from the prewar figures. The Malayan Peninsula, which had a rather good start directly after the war largely because of stock piles found in Singapore and elsewhere, has since been hampered in the rehabilitation of its tin mines and dredging operations by material shortages and, more recently and more severely, by revolts and attacks of communist elements and gangster bands. These hindrances make working in the mines dangerous and form a daily threat against the valuable and highly vulnerable dredges. Contrary to the conditions in Malaya are those on the tin islands of Billiton, Banka, and Singkep-all in the Netherlands East Indies-where the Dutch have re-established peaceful relations with the population. Dutch efforts since the fall of 1945 have been rewarded by continuously increasing production, extension of production facilities, and return of moderate prosperity, complete safety, and all-out co-operation among the population ? native and Chinese ? to the benefit of all concerned.

Jan 1, 1949

This document is Volume II of a two-volume report on underground and surface metal and nonmetal mine fires occurring between 1950 and 1979. Two surface fires from 1980 are included. Volume I discusses the methods of data acquisition, data analysis procedures, and results and conclusions. This volume contains (1) a master list of all fire incidents obtained from MSHA reports, (2) an annotated bibliography of all MSHA reports, journal articles on selected incidents, and non-reportable fires (appendix), and (3) indexes to be used in accessing incidents in the master list and annotated bibliography. These three types of information provide the reader with a complete summary of metal and nonmetal mine fires during the period from 1950 through 1979 and a convenient means to locate incidents of specific interest. The body of this volume is organized around two tables and a series of indexes. The two tables are master lists of underground and surface fire incidents. They are followed by 15 indexes keyed to the master list and annotated bibliography. The Appendix contains three different parts: ? The annotated bibliography of MSHA fire reports (one section each for underground and surface mine fires). ? The annotated bibliography of journal and other periodical articles about selected fires from the MSHA bibliography. ? A listing of non-reportable fires (one section each for underground and surface mine fires). Descriptions of the contents and use of each of the three major components of this volume (i.e., master list, indexes, and appendix) are presented in Section 2.0.

Jan 1, 1980

By Brian W. Stump, David P. Anderson

Identification of seismic events detected under a Comprehensive Test Ban Treaty requires a clear physical understanding of the different types of seismic sources including mining explosions, rock bursts, mine collapse and small, shallow earthquakes. Constraint of the operative physical processes in the source region and linkage to the generation of seismic waveforms with particular emphasis on regional seismograms is needed. In order to properly address the multi-dimensional aspect of data sets designed to constrain these sources, we are investigating a number of modern visualization tools that have only recently become available with new, highspeed graphical computers that can utilize relatively large data sets. The results of this study will provide a basis for identifying important physical processes in the source region that contribute to regional seismograms.

Jan 1, 1995

By B Clements, G Lane

The operations and project environments are very different, but overlap in many areas. The development of mineral processing projects is goal oriented, is schedule focused and is a contractual environment. The operating environment for a mineral processing plant is oriented around longer-term commitments, focused on delivery against budget expectations, and an environment heavily influenced by long-term personal relationships, community relationships, and people issues.Further contrast is evident in the way expenditure is managed. Projects commit large amounts of money quickly to meet schedule-based objectives. Operations manage expenditure to minimise operating costs and are able to, or are forced to delay decisions on large expenditures. However, these two environments need to come together in many ways, ranging from greenfields plant handover to a new operations and maintenance crew, to day to day interaction and management of brownfields projects, often in close proximity.This paper considers the different perspectives people bring to projects and early operations, including the advantages and disadvantages of æoperationsÆ input to a project and models for managing value adding during project development, implementation and debottlenecking.CITATION:Lane, G and Clements, B, 2012. Operations versus projects - How do people think and what are the implications?, in Proceedings 11th AusIMM Mill OperatorsÆ Conference , pp 11-16 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

By Janaina da Silva Vieira

Fibras lignocelulósicas vem se tornando alvo de cada vez mais estudos que visam ampliar o aspecto de suas aplicações. Uma de suas aplicações mais importantes é como reforço de compósitos poliméricos na substituição de fibras sintéticas, que não são ambientalmente corretas. Todavia, as fibras ligoncelulósicas com Malva, Juta dentre outras possuem algumas características negativas para sua incorporação em matrizes poliméricas, como por exemplo, o fato dessas não possuírem boa aderência aos polímeros, pelo seu caráter hidrofílico e do caráter hidrofóbico das resinas. Esse trabalho estudou a incorporação de manta hibrida de fibras de malva e juta em compósitos epoxy DGEBA/TETA para testes de impacto Charpy. Os corpos de prova foram feitos sob pressão para que houvesse uma melhora na aderência. O aumento do volume da manta incorporado gerou um aumento da resistência apresentado que pode ser justificado pelo fato da manta atuar como um bloqueador de trincas.

Oct 30, 2017

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