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In considering the preparation of any paper concerning bearing metals, one feels a certain amount of diffidence in venturing into a field which has been capably explored at great length and in great detail during recent years. Many excellent articles have appeared in technical literature, dealing with the general theory of bearings and of bearing metals, the properties of white metals of the tin-base and lead-base types, and of the recently developed lead-bronzes.The justification for this further excursion into the field lies in the fact that it treats a branch of the bearing metal family which has so far received very little attention, and that of a somewhat sketchy nature, in published papers.The author's object is to give some outline of the history, development, present status and possibilities of the cadmium-base bearing metal alloys, particularly those in which copper is the main alloying element.GENERAL CONSIDERATIONS.It is desirable that attention should first of all be given to the general theory, constitution, and necessary attributes of bearing metals, in order that some of the problems met with during the development work may be better appreciated.Despite some evidence to the contrary, it is fairly generally maintained that an alloy for bearing metal use should be of a heterogeneous nature. It should consist of particles of a hard constituent uniformly distributed through a softer matrix.The basic idea is that the hard constituent should actually bear the load and resist wear, while the matrix imparts the necessary ductility and allows the bearing to align itself on the shaft in service.

Jan 1, 1934

By E. Milke, A. Arnold, B. Friedrich, A. Sydykov

CaF2is often used as a fluoride addition to the chloride salt flux in the melting of aluminium scrap. The solubility of CaF2in the chloride salt system is limited. Dissolved CaF2is considered to improve the properties of salt fluxes. Experimental investigations indicated that the solubility ofCaF2in 70 wt % NaCl/30 wt % KCl, German salt flux used in aluminium scrap melting, might be lower than expected according to literature data. The pseudo binary section CaF2-(70 wt % NaCl-30 wt % KCl) was investigated by differential thermal analysis (DTA). The determined solubility of CaF2appeared to be considerably lower than presented in the literature. The pseudo binary section calculated using thermodynamic data partially confirmed the results. DTA allowed us alsoto determine the crystallization temperature interval of the two phase eutectic consisting of the solid solution NaCl-KCl and CaF2. Keywords: aluminium recycling, phase system, salt flux, CaF2, NaCl, KCl, solubility

Jan 1, 2004

By Fritz J. Klingler

From site demolition, to design, to construction, Detroit's new Tiger Stadium project is required to be completed within a short 2 ½ years from award of the design-build contract. Such extreme schedule requirements together with somewhat difficult ground conditions at the site, resulted in several challenges in the design and construction of the deep foundation system for the stadium. During the geotechnical investigation, an intermittent water bearing sand layer was encountered overlying the hardpan at the site. As a result, some concern developed regarding the potential for collapse of caisson bells within this layer, as well as the potential for flooding of the caissons during drilling. Although sand and/or ground water was encountered within about half of the caissons, standard drilling and belling methods were used, and adverse conditions were controlled in almost all cases through expeditious drilling, inspection and concreting of the caissons. This paper will present a summary of the ground conditions, design and specification requirements, and construction methods used to successfully install the caissons for this project.

Jan 1, 1999

By E. C. Demsky

This paper describes the large diameter caisson foundation for the upstream guidewall at the Lock and Dam No. 26 (Replacement) Project. The guidewall is supported on two rows of 1.8-m diameter concrete filled caissons. The 28.8 m long caissons are embedded 15.5 m into the foundation material and have an unsupported length of 12.2 m. This paper describes the philosophy and design decisions leading to this unique caisson design. The construction success and problems for the load test caisson will be discussed. The full scale 13,350-kN caisson load test and the associated lateral load tests will be described and the test results presented.

Jan 1, 1989

By Anthony H. Tawil

Modern, high-speed machines used in the manufacture of paper require foundations with stringent settlement constraints. To fulfill this requirement, caisson piles, extending into bedrock, were selected to support a paper machine in Baie Comeau for the Quebec North Shore Paper Company (QNSPCo.). This was the fourth machine in an existing paper mill, and its construction was part of an expansion program which included the building of associated structures such as a wood room and chip storage building, and other facilities, Figure 1. The paper mill in Baie Comeau, Quebec, is located in an area which has extensive deposits of sensitive marine clay which are transformed into a viscous liquid when disturbed by external forces such as the driving of piles. Loss of ground and soil disturbance as affected by piling activity assumed considerable importance in the design and construction of the caissons particularly in view of the proximity of existing plant facilities, including another paper machine.

Jan 1, 1987

Increasing demands on quality of metallurgical grade alumina and for lower production costs led to the development of a new fluid bed calcining process. The process, jointly developed in Germany by Vereinigte Aluminium Werke A. G. and Lurgi Gesellschaften m.b.H., takes advantage of modern chemical engineering methods such as counter-current flow of combustion air and solids, direct heat-exchange between combustion air and fine solids, and near stoichiometric combustion of oil in a fluid bed. Using a two-stage Venturi-type suspension preheater for heat-recovery from combustion flue-gases, the circulating fluid bed technique with internal oil combustion at 220°F for the calcining step and a five-stage fluidized bed cooler for heat-recovery from calcines, the process gives an outstanding heat-efficiency. In a first industrial plant for 560 sh. tons/day of alumina heat consumption figures of less than 1·400 B.T.U./lb Al203 g were achieved.

Jan 1, 1972

By S. Mishra, C. Shon, D. Saylak

Only 40% of fly ash generated by the power plants in US are recycled and used for commercial applications. Of these, the high lime, Class C ash had been preferred. Systematic laboratory and field-scale studies have shown that, by including calcium chloride in the mix design of stabilization of roadbed materials, both Class C and Class F fly ashes can be effectively utilized. Test data reveal that the addition of calcium chloride to the system accelerates its curing rate, thereby increasing early strength and long term durability of the constructed road. For road construction, a preblended Class F fly ash–CaCl2 system tends to be more forgiving than the Class C fly ash–CaCl2 system. The former system produces more durable roads. The role of calcium chloride as an accelerator in these systems is discussed along with a mathematical model developed for fly ash- CaCl2 stabilized roadbed systems.

Jan 1, 2007

By Bernard Woolley

The history of the use of calcium aluminates in mining is discussed including a review of very rapid hardening concretes, anchoring using cement capsules and pumped ground control systems. Specific reference is made to the long term performance of highly abrasion resistant orepass lining in South Africa and the use of rapid hardening materials for a range of applications in Australian coal mine where water infiltration creates difficulties or where rapid repair or return to service is required. The topics covered in detail are, high strength abrasion resistant concretes with a 20 year, 30 million ton ore pass life. Rapid reinstatement of wet and worn roadways using mineral dewatering and rapid roadway rebuild solutions, all in I maintenance shift. The different applications are illustrated using examples from operating mines.

Jan 1, 1997

By B. Ndlovu

The world mineral industry has over the years experienced growth in the production of nickel (Ni) due to its use not only in the catalytic industry but mainly also to its demand in the stainless steel production industry. Hence there is a need to produce more pure and marketable grades of Ni through the use of efficient purification routes such as solvent extraction. The V10-LIX®84-IC system resulted in nickel (Ni) extraction isotherm shifting to lower pH levels. The pH window of opportunity for the extraction of Ni subsequently increased in solution containing magnesium (Mg) and calcium (Ca) even though the system also resulted in slight shifts to less positive pH values for Mg and Ca curves. Results showed a synergistic effect of LIX®84-IC when added to V10 for all elements, Ni, Mg and Ca. The pH50 values for elements Ni, Mg and Ca in the V10-LIX®84-IC system were 2.95, 8.10 and 7.70 respectively. Comparing results obtained when using V10 alone produced ?pH50 for Ni, Mg and Ca being 3.35, 0.15 and 0.70 respectively, which was a confirmation of the synergistic shifts for all the elements. The ?pH50 (Mg-Ni)value was 1.95 with no synergism and 5.15 with synergism and that for ?pH50 (Ca-Ni)was 2.10 with no synergism and 4.75 with synergism. This showed that the Ni-Mg separation factor was relatively larger than the Ni-Ca. Improved loading and stripping kinetics were also observed. Keywords: Nickel solvent extraction separation, magnesium, calcium, versatic 10 acid and LIX®84-IC.

Jan 1, 2008

By Y. I. Rabinovich, S. C. Brown

In the Florida phosphate industry, fatty acid collectors are used to separate phosphate ore from silica during the rougher flotation stage. However, the presence of multivalent ions (in particular Ca++) in the processing water has been reported to result in the activation of silica with respect to oleate adsorption, rendering it floatable. Hence, adequate separation may not be achieved during the rougher flotation stage. In this study, the direct measurement of surface inter-action forces via atomic force microscopy was used to delineate possible mechanisms for calcium activation under phosphate flotation conditions at oleate/calcium concentrations both above and below the calcium dioleate precipitation limit.

Jan 1, 2004

By Janice K. Means

The purpose of this paper is to provide the seminar attendee with: information on pipeline construction, operation and standards to better equip him (or her) to analyze the ultimate effect of blasting stress on pipelines; an introduction to the analysis of blasting effects to pipelines using the American Gas Association analysis method; and; supplemental sources useful in the analysis of blasting effects to steel pipelines, and, in particular, on natural gas pipelines.

Jan 1, 1992

By J. -Y. Jia, G. -B. Qiu, C. -G. Bai, D. -F. Chen

Due to the great importance of the smelting process, it is essential to establish a calculation model on the viscosity of the slag system containing titania. In this paper, the calculation models of mass action concentrations and viscosity for the CaO-SiO2-TiO2slag system have been established according to the coexistence theory of the slag structure, as well as the referenced viscosities ofCaO-SiO2-TiO2at different temperatures and TiO2compositions. With the two models, corresponding calculated programs are made by means of programming language Matlab5.3, and the curves of viscosity of the TiO2concentration (?TiO2/%) at 1400°C, (R=0.9~1.0) are plotted. The results show that mass action concentrations of TiO2increases with increasing percentage ofTiO2, while the viscosity of CaO-SiO2-TiO2system is decreased. The results show that the models are in good agreement with the experimental and referenced data. They also shows that the models are reasonable for the CaO-SiO2-TiO2slag system. Keywords: coexistence theory; CaO-SiO2-TiO2slag system; viscosity ; calculation models.

Jan 1, 2004

By D. J. Fourie

During the production of pure TiO2for the pigment industry, ilmenite, containing 35?60% TiO2, is reduced to high titania slag, containing 70?95% ?TiO2? and pig iron. The high titania slag produced, consists mainly of titanium in different oxidation states and FeO in equilibrium with liquid iron. To predict the phase and chemical reaction equilibria in a furnace, a suitable solution model is required with accurately determined binary interaction parameters, as slag melts tend to behave very non-ideally. This paper investigates two popular slag models, namely, modified quasi-Chemical (MQC) model and the cell model and provides the binary interaction parameters based on recently published data of the ternary system and critically assessed published unary and binary data. Very few modelling results have been published on the ternary Ti-Fe-O system pertaining to high titanium slags. The solution models, with their regressed interaction parameters, can subsequently be implemented in commercial software of the slag-metal phase equilibria to predict how much and which type of solids will precipitate for a given bulk slag chemistry and operating temperature or, alternatively, above which temperature should a furnace be operated to avoid excessive solids precipitation.

Jan 1, 2005

Calculations of the temperatures of metal, coke, and gas at any level in the cupola furn~ce can be carried out by means of heat balances, using data obtained from experiments with an 18 in. experimental cupola. The results can, to a certain extent, be verified by means of heat transfer calculations.The curves thus obtained, showing the variation of temperature with height in the cupola, provide a valuable picture of the heat transfer processes in a shaft 'furnace.INTRODUCTIONThe Brown Coal Research Laboratory, of the University of Melbourne, has been engaged in recent years on a programme of iron-melting tests in an experimental cupola furnace.Although the ultimate aim of this work is to develop brown coal char as a cupola fuel, most of the experimental work so far has been with conventional coke. The testing programme was designed to provide information on the effect of variables such as blast rate, metal-coke ratio, and coke size on the overall melting process, e.g. melting rate, temperature of metal tapped, and stack gas composition.However, in many cases data were obtained on conditions inside the furnace by measuring temperatures and gas compositions. The aim of the work described in this paper was to qevelop a method for using this data to obtain information on the processes taking place in the cupola.Very little research has been done on the combustion of fuels in shaft furnaces. Early work on this subject, as well as the initial stages of the Brown Coal Research Laboratory's programme, has been discussed by Evans (1959). The use of probes for obtaining information on conditions in the interior of a shaft furnace was pioneered by Belden (1913)...

Jan 1, 1963

By Janshi Sen

VERTICAL-INTENSITY magnetometers, such as the Hotchkiss Superdip and the Askania vertical field balance, are now [ ] widely used, because vertical-intensity charts give definite information for the location of upper pole, dip and strike, and approximate shape of the deposit. Again, a slow and steady increase of dip over a large area indicates a large deep-lying deposit, while a large dip limited to a small area and falling away rapidly suggests a small and shallow one. The complication comes more from the richness of the ore. A large body of lean ore near the surface might produce the same vertical-intensity chart as a rich ore at depth. This paper presents a method for calculating the maximum depth of a single-pole deposit and another for a two-pole mineral body, by utilizing data of both vertical and horizontal intensities as obtained by a Thalen-Tiberg magnetometer. As shown on the left side of Fig. 1, lean ore, rich ore and a single pole produce the same magnetic field. The depth of the pole, [ ] h, can be calculated from the following relation: [h=a=tan¢=G-F h=aXFy] where G is the vertical intensity at point A due to the pole; F, the horizontal intensity of the same; and a, the distance from the point of maximum vertical intensity or the vertical projection of the pole on the surface to the point of observation A. If an entirely covered deposit is indicated by magnetic measurements and boring cost estimated from the calculated depth is so reasonable as to encourage drilling, the ore should be struck somewhere within the limit of the calculated depth by the borehole. A number of such points as A should be taken for calculation, erratic results should be rejected and the average figure used for cost estimation.

Jan 1, 1944

By E. J. Magri

Consideration is given to the problem of the estimation, from limited data, of the likely grade and tonnage for a new mining property that is to be exploited by the selective mining of two metals that have substantial contributions to make to the total revenue. In particular, the case of a new gold and uranium mine in South Africa is analysed as follows. (I) The applicability of the underlying lognormal bivariate model for different support (i.e. ore unit) sizes is examined. (2) The necessary parameters for the bivariate lognormal models for different block sizes are estimated from abundant chipsampling data from a section of the Hartebeestfontein Gold Mine using alternative approaches, and the results are compared. (3) A method is given for obtaining the necessary parameters for a tonnage-grade relationship relative to a joint pay limit from the very limited information likely to be available at the end of the exploration stage of a gold mine, and the results are compared with those obtained from the large volume of data available from a minedout area.

Jan 1, 1982

By William W. Edgerton

The California Department of Transportation (Caltrans), the Contra Costa Transportation Authority (CCTA), and the Alameda County Congestion Management Agency (Alameda CMA) are involved in a unique partnership on the planning and design of the fourth bore of the Caldecott Tunnel, located on State Route 24 in Alameda and Contra Costa counties. The project will add a two-lane bore north of the existing three bores. The project will alleviate traffic congestion in the non-peak direction. This paper provides background on the existing facility, summarizes the need for the new fourth bore, describes the proposed improvements, sets forth the approach for project delivery, and lists some of the challenges that are expected during construction.

Jan 1, 2008

Judicious placement of a range of geotechnical instruments was employed at the Tasmania gold mine, Beaconsfield, Tasmania, as a key strategy in the monitoring of rock mass conditions over the past four years. The range of instruments employed included vibrating wire stress-meters and hollow inclusion cells to monitor changing stress conditions, resistance wire and multipoint borehole extensometers to monitor the impact of stress changes on the integrity of the rock mass, and instrumented cable bolts and threadbar bolts to monitor the static and dynamic impact of rock mass changes on the installed ground control system. Initially the monitoring was of a qualitative nature, monitoring change from the time of installation. The value of the output was considerable when considered in relation to the ongoing seismic record which was also being monitored. It was clear from the seismic record and the monitoring results that stope blasting was the primary trigger for changing rock mass conditions. However, it was unclear how well observed behaviour was reflecting conditions anticipated by elastic numerical modelling. The latter had predicted significant stress increase in the near field of man-access footwall development. Qualitative monitoring and visual inspection did not support the modelling prediction, and this led to a program of quantitative measurement being undertaken. Measurement of the absolute stress condition in the backs of footwall development immediately adjacent to monitoring hollow inclusion cells provided the benchmark for tracking quantitative stress change. The program provided insight into the evolution of principal stress field magnitude and orientation in relation to rock mass change observed with extensometers and instrumented ground control elements, as well as providing a degree of calibration between the elastic numerical modelling and the virgin stress field. Calibrated monitoring data has also provided a useful benchmark for finite element modelling which is to be used for future mine-wide design.

Nov 25, 2010

By Andre C. Zingano

It is a very difficult task to estimate the immediate roof and support behavior in a room-and-pillar mining section in the initial phase of the mining project. There is little information available at this phase, and it is restricted to geomechanic characterization of the rock layers from cores samples, and the in-situ instrumentation of experimental entries and intersections. Even being a pilot excavation for roof support test a good indicator for the behavior of the immediate roof, its behavior for a full excavation mining section is different from a single intersection of two entries, mainly because the stress redistribution caused by the multiple entries excavation and face advance for a full excavation section. The objective of this paper was to calibrate a 3-D numerical model of an experimental intersection, based on the in-situ instrumentation of an experimental intersection excavation, and the geomechanic description of the rock layers. The numerical model was built with the same specifications as the excavation test, including the entry geometry and roof support. The numerical model calibration was based on wire extensometers that were installed at different positions in the roof of the pilot excavation, and on the geomechanic characterization of the rock layers that form the roof, coal seam, and floor. Therefore, it is possible to estimate whether the roof support specification adopted in the test phase will be good enough for the development of the entire mining section.

Jan 1, 2009

By Keith A. Heasley

The LaModel program has been used successfully in the United States for many years to design pillars to ensure global stability of pillar recovery operations. However, the recent Crandall Canyon Mine collapse showed that further research was required to improve the design of pillar recovery under deep cover. Toward this end, a new calibration procedure was implemented in LaModel. This calibration procedure prescribes techniques for calibrating the critical LaModel input parameters based on empirical abutment loading and pillar strength, as utilized in the time-tested ALPS and ARMPS programs. The calibration procedure is intended to help guide a novice modeler in choosing calibrated input parameters that produce a standard model that fits within the verification database. However, the rigid parameter specification incorporated in the calibration procedure also removes most of the flexibility in LaModel for specific calibration to the unique conditions at a given mine site. In this paper, a number of the LaModel input parameters are varied outside the bounds of the suggested calibration and the effects on the model results are analyzed. Ultimately, it is shown how the LaModel user might vary certain input parameters to adjust the model to site-specific conditions, while still maintaining the general accuracy and philosophy of the recommended calibration.

Jan 1, 2012