Search Documents

By Gupta R. C

Direct reduction of iron ore by solid reducing agents have been studied extensively and summarised by several authors (Otsuka and Kunii, 1969; Abraham and Ghosh, 1979; Frauhan, 1977; Rao, 1971; Kawasaki, Sanscainte and Walsh, 1962; Ghosh, 1970; Rao, 1979). While studying the reduction behaviour, it is generally agreed that the reduction occurs via gaseous intermediate, generated by carbon gasification reaction which involves mass transfer, heat transfer nucleation and growth, etc through a) reduction reaction occurring at solid reductant, and b) reduction reaction occurring at solid iron oxides, thus making the overall reduction process very complex in terms of clearly defining the reduction kinetics of the system. In addition to this, practical difficulties like correctness of reaction temperature, (Seaton, Foster and Velasco, 1983) difficulties in isothermal temperature studies of reduction, difficulties in monitoring the reduction process while using gaseous reductants and separation of reduction by volatile matter from overall reduction process make the reduction kinetics more complex (Misra).

Jan 1, 1999

By L. E. Shiffman

W. J. Parton—Those operators faced with the problem of treating fine coal whether in bituminous or anthracite will find this paper most timely. I would like to take this opportunity of discussing Mr. Schiffman's paper and at the same time express certain views relating to our Tamaqua plant. I would like to ask the author what type of impeller and diffuser is used in the Denver cells? Screen analysis of products from individual cells indicate that coarser material resists flotation and only floats after greater retention time in the last few cells. Also, the need for a scavenger screen to reclaim non-floated coal particles further stresses this point. I have always felt that more efficient means of cleaning coal between 10-mesh and 28-mesh existed than flotation. Reagent and power costs are high for the flotation process. When floating +28-mesh particles, cell capacity is lowered and some of the particles are lost with the refuse. The Tamaqua plant of the Lehigh Navigation Coal Co. floats —28-mesh coal and capacity of recoverable coal is 40 tph for 1800 cu ft of Denver cells; or 0.05 tons per cu ft of cell. At Kimberly 7.75 tph for 600 cu ft of cell gives 0.013 ton per cu ft of cell. At Bessie 14 tph for 800 cu ft of cell gives 0.017 tons per cu ft of cell. It would be appreciated if the author would comment on what he feels is the upper size limit of particle to attain most efficient utilization of the flotation process. The dewatering screw is a very interesting development since it offers a simple way to prepare coal sludge for more complete clewatering by drainage or mechanical dewatering on screen or filters. In other words it could be used to accomplish the same thing as a thickener tank. I would appreciate having the author's comment on how he thinks such a screw dewaterer would work on a froth.* The process as used in floating coal at the Bessie and Kimberly plants may be referred to as more of a bulk oil float in contrast to a froth flotation process. Experiments on increasing capacity of cells is most interesting since we are going through such an experi- mental period at the present time. Recently a double overflow was installed on our No. 30 Denver cells. So far results are not conclusive. In reviewing this paper the following comments are made pertaining to investigation of methods for increasing capacity: Supercharging: Supercharged air in matte flotation or for that matter the use of the normal amount of air drawn in by the impeller would in all probability cause such an aeration in the cell as to destroy the buoyant effect given to the coal particles by the excessive amount of kerosine used. In other words, air creates an agitation zone throughout the cell, creating a boiling and thereby giving a lower recovery in the cell. It would be interesting to know whether the 7 pct increase in recovery was with no air being admitted to the stand pipe. Changing Impeller Speed: The speed of a receded disc impeller for a No. 30 cell as recommended by the Denver Equipment Co. is, I believe, approximately 250 rpm. At this speed and using supercharged air in excess of 8-oz pressure, we have observed a boiling action in the cells. In our flotation we endeavor to obtain some degree of froth flotation using pine oil as a frother. The boiling action as caused by increasing the amount of air added to the cells is detrimental to recovery in froth flotation. It is our belief that to obtain increased recovery from a cell in froth flotation, additional air must be introduced but at the same time this air must be dispersed throughout the pulp in the form of small bubbles and this can only be done by increasing the speed of the impeller. Therefore, if Mr. Schiffman decreased the speed of the No. 30 impellers and at the same time continued to use supercharged air, the boiling action may have been increased because larger bubbles developed. The lower recovery as reported could be due to this factor. Decreasing the impeller speed will definitely decrease the power consumed but may have other disadvantages. First, we believe it will permit "sanding" in the cell and this in our opinion will increase the wear on the impeller and diffuser, especially so, if there is pyrite and/or sand present in the feed. "Sanding" in the cell when air is used, as in froth flotation, will effect the dispersion of this air and cause boiling.

Jan 1, 1951

By L. E. Shiffman

W. J. Parton—Those operators faced with the problem of treating fine coal whether in bituminous or anthracite will find this paper most timely. I would like to take this opportunity of discussing Mr. Schiffman's paper and at the same time express certain views relating to our Tamaqua plant. I would like to ask the author what type of impeller and diffuser is used in the Denver cells? Screen analysis of products from individual cells indicate that coarser material resists flotation and only floats after greater retention time in the last few cells. Also, the need for a scavenger screen to reclaim non-floated coal particles further stresses this point. I have always felt that more efficient means of cleaning coal between 10-mesh and 28-mesh existed than flotation. Reagent and power costs are high for the flotation process. When floating +28-mesh particles, cell capacity is lowered and some of the particles are lost with the refuse. The Tamaqua plant of the Lehigh Navigation Coal Co. floats —28-mesh coal and capacity of recoverable coal is 40 tph for 1800 cu ft of Denver cells; or 0.05 tons per cu ft of cell. At Kimberly 7.75 tph for 600 cu ft of cell gives 0.013 ton per cu ft of cell. At Bessie 14 tph for 800 cu ft of cell gives 0.017 tons per cu ft of cell. It would be appreciated if the author would comment on what he feels is the upper size limit of particle to attain most efficient utilization of the flotation process. The dewatering screw is a very interesting development since it offers a simple way to prepare coal sludge for more complete clewatering by drainage or mechanical dewatering on screen or filters. In other words it could be used to accomplish the same thing as a thickener tank. I would appreciate having the author's comment on how he thinks such a screw dewaterer would work on a froth.* The process as used in floating coal at the Bessie and Kimberly plants may be referred to as more of a bulk oil float in contrast to a froth flotation process. Experiments on increasing capacity of cells is most interesting since we are going through such an experi- mental period at the present time. Recently a double overflow was installed on our No. 30 Denver cells. So far results are not conclusive. In reviewing this paper the following comments are made pertaining to investigation of methods for increasing capacity: Supercharging: Supercharged air in matte flotation or for that matter the use of the normal amount of air drawn in by the impeller would in all probability cause such an aeration in the cell as to destroy the buoyant effect given to the coal particles by the excessive amount of kerosine used. In other words, air creates an agitation zone throughout the cell, creating a boiling and thereby giving a lower recovery in the cell. It would be interesting to know whether the 7 pct increase in recovery was with no air being admitted to the stand pipe. Changing Impeller Speed: The speed of a receded disc impeller for a No. 30 cell as recommended by the Denver Equipment Co. is, I believe, approximately 250 rpm. At this speed and using supercharged air in excess of 8-oz pressure, we have observed a boiling action in the cells. In our flotation we endeavor to obtain some degree of froth flotation using pine oil as a frother. The boiling action as caused by increasing the amount of air added to the cells is detrimental to recovery in froth flotation. It is our belief that to obtain increased recovery from a cell in froth flotation, additional air must be introduced but at the same time this air must be dispersed throughout the pulp in the form of small bubbles and this can only be done by increasing the speed of the impeller. Therefore, if Mr. Schiffman decreased the speed of the No. 30 impellers and at the same time continued to use supercharged air, the boiling action may have been increased because larger bubbles developed. The lower recovery as reported could be due to this factor. Decreasing the impeller speed will definitely decrease the power consumed but may have other disadvantages. First, we believe it will permit "sanding" in the cell and this in our opinion will increase the wear on the impeller and diffuser, especially so, if there is pyrite and/or sand present in the feed. "Sanding" in the cell when air is used, as in froth flotation, will effect the dispersion of this air and cause boiling.

Jan 1, 1951

By R G. Moreby, S Bluhm, FávonáGlehn, C Pascoe

Resolution Copper Mine in Arizona, USA, is planned to be a 2000 m deep panel cave mine with virgin rock temperatures exceeding 80¦C in rock with high crystalline silica content, resulting in a very challenging ventilation and cooling system design. This is one of the largest copper orebodies ever found and, with a planned rock production rate of 120 kton/day. The project is currently in its prefeasibility phase and the paper discusses features of the ventilation and cooling system design which includes multiple ventilation shafts with total primary ventilation flow of about 3000 m3/s and both surface and underground refrigeration plants producing more than 140 MW refrigeration capacity. The cooling system features large surface bulk air coolers chilling all downcast air supplemented by an underground secondary air cooler system and a chilled service water system. This will be a very challenging mine to ventilate and cool but this work has demonstrated that it will be technically achievable with the application of existing technology.CITATION:Bluhm, S, Moreby, R G, von Glehn, F and Pascoe, C, 2013. Life-of-mine ventilation and refrigeration planning for Resolution Copper Mine, in Proceedings The Australian Mine Ventilation Conference , pp 125-138 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 1, 2013

By B. H. Moore

Foundation and excavation problems associated with lock construction projects vary widely. Each lock requires a different foundation to respond to a unique geologic setting. The range of heights and founding materials are illustrated thru description of selected structures encountered in the United States. Examples range from 113-ft high John Day Lock on the Columbia River founded on basalt rock to the 17-ft high Lock No. 5 on the Arkansas River floated on a clay foundation. A description of the basic elements of design and construction is presented. Several case histories involving lock design and construction are assessed to aid in recognition of potential problem areas on forthcoming construction. In the past decade there have been many improvements in construction materials and techniques. The application of these new approaches to lock construction is discussed.

Jan 1, 2010

By Prasad S, Chatterjee S. S, Singh B. N

The chief source of metallic iron for steelmaking in India, even today, as it is in most part of the world, is through blast furnace (BF) route. This will continue to be so in the foreseeable future as the technology is most efficient, both process and economy-wise. However, as the world is moving into the next millennium, a critical look is being given to the process primarily because of its non-ecofriendliness (as a result of extensive use of metallurgical coal/coke requiring elaborate pollution control facilities) and huge investment involved for supporting facilities like extensive raw material preparation and handling, agglomeration, adoption of sophisticated instrumentation and control system, etc.

Jan 1, 1999

In March, the Minister of Mines, Mrs. Judy Erola, released a mineral discussion paper at the annual meeting and convention in Toronto of the Prospectors and Developers Association. Among the mineral objectives discussed was the revitalization of the "junior" mining industry. That industry reportedly has seen its share of total exploration expenditures fall from 50% in 1969 to 10% in 1979. Some sources believe the reason to be the rise of exploration costs and more- restrictive legislation The junior mining industry reportedly was responsible for 40% of all mineral discoveries in the 1969-79 period. CZECHOSLOVAKIA Czechoslovakia expects its capacity for the recovery of gallium metal to increase from 1,650 kilograms to nearly 3,000 kilograms per year by the installation of new recovery equipment at the aluminum plant at Ziar Nad Hronom in Central Slovakia. World production data are not reported, but the United States consumed 8,000 kilograms (estimated) in 1981, of which 5,536 kilograms were imported. Gallium is recovered as a byproduct of the Bayer process for the conversion of bauxite to alumina, and from certain zinc processing wastes. It is used for electronic applications such as light-emitting diodes for visual display panels in calculators, clocks, and other instruments.

Jan 1, 1982

This information circular describes research the Bureau of fines has conducted to improve technology for recovering precious metals from low-grade resources. Many of the reported findings are recent, and some of the work described is ongoing. Topics discussed include cyanidation of carbonaceous gold ores to enhance gold recovery, a new method for precipitating mercury during cyanide leaching of gold ores, a staged heap leaching process to generate suitable solutions for direct electrowinning of gold, the use of anion-exchange resins to recover gold from cyanide solutions, and precious metals recovery from electronic scrap.

Jan 1, 1986

By Edwin A. Clarke

[For almost 2 decades the Bureau of Mines has been Interested in converting solid fuels to liquid fuels. Small-scale laboratory investigations were carried on for a number of years.4/ This work wad expanded substantially under authority of Public Law 290, approved by the 78th Congress on May 5, 1945. As part of the. broadened program, coal-hydrogenation demonstration plant was designed and erected at Louisiana, Mo., where: hydrogen-manufacturing and compression equipment, shoes, electric power, and other utilities and facilities were available from a discontinued wartime ammonia works . The plant uses the direct -hydrogenation or Bergius process, but the process differs from prewar European practices in many respects. Many noteworthy improvements h eve bean made, particularly by substituting automatic instruments for manual control of process variable's, in line with modern American processing practices. The over-all objective of the demonstration plant is to bridge the gap between laboratory end commercial-scale operation by furnishing cost and engineering data to develop a synthetic liquid-fuels industry when it proves technically and economically justified. Fitting into the over-all program, specific objectives o early runs were to (1) train personnel who had no experience with this type of operation, (2) break in the installed equipment, (3) obtain successfully integrated operation of the entire plant, and (4) work towards obtaining data on the hydrogenation of coal-tar oil and a typical low-ash coal. In beginning fan integrated operation, it is common practice to operate and obtain reaonably smooth performance of each unit before the over-all operation is undertaken. The first part of the plant completed was the refinery, consisting of several fractionating systems, a stabilizer, and a chemical treater.]

Jan 1, 1953

Drill cores from Section 62, New Broken Hill Consolidated Ltd., were used to study the petrology of rocks associated with the zinc lode. The distribution of the rock types in relation to the lode structure was determined. The distribution of the gahnite-bearing rocks was shown to be only partly conformable with the structure.It was concluded that large scale metasomatism was not widespread, that the rocks associated with the lode (except, perhaps, the quartz-gahnite-garnet rocks) were formed by metamorphism of sediments, and that rocks and lode were contemporaneously metamorphosed.INTRODUCTIONThis investigation was undertaken in order to study the rock types associated with the zinc lode of the Broken Hill orebody, and their relationship to the structure of the ore horizons. The work was confined almost entirely to the laboratory, and is therefore limited in its scope. It is hoped, however, that the information gained may throw some new light on the genesis of the lode.Certain inferences which are drawn from this work are at variance with the ideas of a number of earlier workers.In particular, the idea of large scale metasomatism developing many of the rocks associated with the lode, especially those containing manganese, is questioned. On the contrary, the rocks associated with the lode are more simply explained as highly metamorphosed sediments, in some cases modified by water introduced from surrounding rocks into zones of strong folding and faulting. As a corollary, a metamorphicsedimentary origin for the lode material, either as a concentrated sulphide deposit, or somewhat disseminated...

Jan 1, 1961

By Peter M. Watt

The objective s of this paper are: (a ) to examine and discuss the burdens we place on our extractive industry; (b) to compare the levels of taxation in Canada with those in other countries; and ( c) to suggest certain broad parameters within which our taxation policies may be made more rational and stable. Among the burdens identified are taxation, the ownership and use of our resources, environmental issues and the rather emotional issue of so-called 'super profits'. Finally, the paper will address certain broad but key areas of policy which need attention and agreement if our tax system is to be made more rational. Such areas include: whether and if so why the extractive industry should be given incentives;. what circumstances, if any, justify a 'higher' than normal' level of taxation, and, ?if the concept of economic rents is a justifiable one, how might a basis for them be established which recognizes the fluctuating value of much of the industry's output. Note: The paper was written before the 1977 Federal and Provincial budgets were presented. Consequently, the paper does not reflect any changes proposed in these budgets.

Jan 1, 1977

By Zorigtkhuu Davaanyam, Bern Klein, Stefan Nadolski, Amit Kumar

"The High Pressure Grinding Rolls (HPGR) is a relatively new comminution technology that has been shown to be more energy efficient compared to semi-autogeneous (SAG) mills. Full and fair consideration cannot be given to HPGR-based comminution circuits in early stage projects, because presently pilot scale testing is required for assessing and sizing; pilot scale testing requires bulk samples weighing more than one tonne. A CAMIRO research program was conducted at the University of British Columbia to develop bench scale tests that would reduce the quantity of sample required to assess HPGR.Three test procedures were developed.1. The Direct Calibration Methodology calibrates piston press test results to pilot scale test results such that piston press tests can then be used to determine the energy–size reduction relationship for a range of ore types.2. The Database Calibrated Methodology, which is similar to the Direct Calibration Methodology except that it calibrates piston press tests against a database of pilot scale and piston press tests.3. The Semi-Mechanistic Methodology was developed to use piston press test results as an input for an HPGR based energy-size reduction performance model.Through utilization of these methodologies, the energy–size reduction performance of an HPGR can be predicted with minimal sample requirement. In addition, piston press testing is far more cost effective, faster, and accessible than pilot-scale HPGR testing.IntroductionOne could argue that in the future, decisions regarding selection of comminution circuits will be made primarily on the basis of energy consumption. The following facts and predictions support the argument:"

Jan 1, 2015

Unrelieved residual strains can influence the states of stress in rock masses. If cheap, stable structures are to be constructed in Tock in which large pressures are exterted by unrelieved residual strains, the pressures must be either utilized or neutralized. A photoelastic technique has been used to show that the release of residual strains in rocks is influenced by the mechanical properties of anisotropic rock fabrics. The relationships between directions of residual strain release and the attitudes of minor geological structures have been determined. For engineering design purposes it is possible to estimate the principal stress directions in rock containing unrelieved residual strains if the attitudes of such minor geological structures as foliation planes, lineations, and joints are known.INTRODUCTIONQuarry workers have long been aware that near-surface rocks may be highly stressed. In many cases the stresses are too large to be the result of gravitational loads. Dale (1923, pp. 34-35) gives many instances of deformation produced by the violent release of residual strains in quarry rocks. Coates (1963) has described powerful rock bursts and cases of rock deformation underground implying the existence of much larger stresses than are likely to result from present-day gravitational loads. The only explanation is that pressures of up to several thousands of pounds per square inch may be caused by unrelieved residual strains in rock.Instruments have been developed for measuring states of stress in rock masses. Most stress determinations in rock have been made on the assumption that rock behaves as a simple elastic material. It is now known that rock is a...

Jan 1, 1964

By A. W. Popp

After forty years of exploration and development, the heavy mineral sand deposits of the Murray Basin are on the eve of substantial exploitation by Iluka Resources Limited, Southern Titanium NL and RZM/Cable/Bemax, whom plan to initiate mining and processing operations in 2005. A trial mining and processing operation was undertaken on the Wemen North strandline deposit in 2001-2003 by Murray Basin Titanium, a joint venture of Sons of Gwalia and RZM/Cable, which brought to light a number of mining and processing problems which have since been the subject of extensive studies and process development work. The mineralogy of these weathered strandline deposits is complex by industry standards due to the variety of the heavy minerals present, coatings on the mineral grains and the extensive weathering and alteration which has taken place during the past 50 million years. This paper provides an overview of the complex mineralogy that, in turn, dictates the processes that can be used to recover the valuable heavy minerals. The Murray Basin encompasses some 300,000 km2 and has been a depositional basin, often land locked, since the start of the Cenezoic Era. The economic heavy minerals include ilmenite, altered ilmenite, leucoxene of highly variable composition, rutile, and zircon. There are also other heavy minerals present such as cassiterite, chromite, and monazite in quantities that pose both problems and opportunities. The clay content and overburden thickness also play a major role in the selection of the deposits to be mined. Project Services Consultants (PSC) has undertaken the preparation of this paper as part of its ongoing participation in the mineral sands industry and in particular the project development activities in the Murray Basin region currently being undertaken by Iluka Resources. PSC has been involved with the mineral sands business for several years with senior staff having in excess of 30 years global industry experience. The company is well placed to provide a range of services to clients like Iluka Resources in the areas of project development, execution and strategic development and industry advice.

Jan 1, 2005

A broker relies heavily on mineral valuations and independent experts' reports to provide the fundamental information, both technical and commercial, which provides the basis of estimating the sharemarket value of securities and underlying assets. It is important to appreciate the significant variance that can occur between the market value and other types of valuation at a particular point in time. In general, most experts' reports and valuations seek to provide estimates of technical/fundamental or ""fair"" value which correspond to the Corporations Law and accounting standards requirements. They do not usually attempt to estimate (stock) market values and it is usually and quite correctly the broker's task to estimate market values on the basis of a technical appraisal and consideration of all other commercial, market and financial influences. Therefore ideally, an independent experts' report or information memorandum will include material relating to commercial and management aspects of a company as well as detailed technical reviews and fundamental valuations. Wherever sensible cash flow projections can be made, cash flow-derived valuations, usually based on discounted cash flow (DCF) calculations, remain the preferred valuation methodology. Brokers in general would not argue with this preference. However, there is a paucity of examples of valuations where alternative methods are applied as a check on the reasonableness of a DCF-based estimate.

Jan 1, 1994

By J. O. Marsden

This paper presents an overview of the innovative methods for gold and silver extraction that have been put into actual practice in North America since 1987. It is an update of a paper of the same title which was presented by Sass and Mansanti at the AMC conference in San Francisco in 1987. New practices, new equipment and variations of older practices that have been introduced in the last five years are discussed in each of the following categories: process selection trends, comminution, gravity concentration, flotation, oxidation, agitated and vat leaching, heap leaching, solution concentration and purification, zinc precipitation, electrowinning, tailings disposal detoxification, and reclamation.

Jan 1, 1993

By Masaki Kitazume

Deep mixing method, in-situ admixture stabilization technique, has been developed and adopted for on land and marine construction works in Japan. The geotechnical design procedure of the method has been standardized in Ministry of Land, Infrastructure and Transport Government of Japan for port and harbor facilities, which includes the block type and wall type improved grounds for foundation stability, settlement reduction purpose. This procedure is based on the allowable stress concept, in which the induced stresses within the improved ground are confirmed to be lower than the allowable strength in the internal stability calculation. This procedure has been cited by several organizations to establish their standards. The Ministry has a plan to introduce a reliability based design for marine construction works in 2006, in which the design procedure on DM improved ground will also be modified to the reliability based. In the new design procedure, the average and variation of soil parameters and external loads are incorporated by partial safety factors to investigate the stability of improved ground. According to the plan, the author has been studied the design procedure and the magnitude of partial safety factors, and has established a preliminary draft of the standard. This draft will be brushed up through comparing the current design procedure. In this article, the design concept and design procedure of the method are briefly described.

Jan 1, 2004

MR. RIGG: Gentlemen, I would like to welcome you all to the symposium this morning. My name is Jack Rigg, and I m a special assistant to Hollis Dole, Assistant Secretary of the Interior for Mineral Resources. Hollis is not in town this morning, and I am here to pinch-hit for him. The first order of business this morning is remarks by the Honorable Russell Train, Under Secretary of the Department of Interior. Mr. Train. MR. TRAIN: Thank you, Mr. Rigg. Lest you think that Hollis Dole is not interested in this symposium, let me just say that fie is flying back from Australia just to be here. He is heading up a United States delegation in Australia meeting on resource problems in the Pacific. And I believe he will be here about noon.

Jan 1, 1970

By David E. Albus, Ahmadreza Mortezaie, Bidjan Ghahreman

The structural evaluation of seismic performance of an existing hospital in Long Beach, California, required spring constants of foundation elements. The structure included support by deep foundation elements comprised of belled (underreamed) caissons. The available relationships in the governing building code (ASCE41-13) to compute axial stiffness is not applicable due to the belled configuration of the caissons. The large diameter of the bells required consideration of the foundation medium to the axial stiffness; a detail not clearly described in ASCE 41-13. Furthermore, prescriptive equations in ASCE 41- 13 used to estimate lateral stiffness only consider pile groups with the assumption that the only source of lateral stiffness is the axial reaction of individual piles. These assumptions were invalid for the project at hand where all caissons are configured as single foundation elements, not a pile group. In the present work, the approach taken to estimate seismic stiffness of single-belled caissons is described which accounts for the elastic behavior of the foundation medium below the bell base and lateral behavior of single-pile shafts. Results of the work provide a more satisfactory derivation of the spring constants consistent with current modeling methods. INTRODUCTION Seismic evaluation of an existing hospital in Long Beach, California, required geotechnical investigation followed by site-specific ground motion analysis. This evaluation was required by the Office of Statewide Health Planning and Development (OSHPD) in order to meet the requirements of the Structural Performance Category 4D (SPC-4D) published as a part of the 2016 California Building Code, CBC (Section 3412A). SPC-4D utilizes ASCE41-13, as modified by OSHPD, and involves two seismic performance objectives: BSE-1E (20% probability of exceedance in 50 years) and BSE-2E (5% probability of exceedance in 50 years). Spring constants and capacities of foundation elements were needed for evaluation of the structural performance of the building subjected to these two performance objectives. Our review of the as-built foundation plans indicated that both shallow footings and caissons were used for support of the structure. The plans demonstrated that all caissons are belled (under-reamed) and are individual, i.e. not part of pile groups. In this paper, the subject site condition and foundation elements are described first. This is followed by details of assessing spring constants and vertical capacities for belled caissons. The new requirements of the 2016 CBC concerning the evaluation of critical facilities will likely entail evaluation of other structures with belled caissons due to the more extensive use of these foundations in the past. This paper proposes a method to address the conditions of individual belled caissons not explicitly considered in the current code provisions.

Jan 1, 2018

By K. V. Raj, R. Jacksha

Conveyor systems persist in being a source of injuries and fatalities in the mining industry. To reduce these incidents, better methods are needed to enhance the monitoring of probable hazards and improve situational awareness during the normal operation and maintenance of conveyor systems. To address these issues, researchers from the National Institute for Occupational Safety and Health (NIOSH) continue to investigate emerging technologies that show the potential to improve miner safety around conveyors. This paper presents a feasibility assessment by NIOSH researchers of a fully integrated, commercially available wireless Internet of Things (IoT) system to improve situational awareness around conveyor systems. Included are discussions of a full-scale laboratory test bed that was designed to simulate a working conveyor system as well as the challenges and successes of integrating the IoT system with the test bed.

Oct 6, 2020