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By F. Lindroos

A cornerstone in the LKAB Green Pellet concept is to produce pellets with a small footprint in terms of energy con-sumption, CO2 emission and emission of other elements harmful to the environment, like dust, sulphur dioxides, nitrogen oxides, chloride and fluorine. The concept also encompasses our determination to make pellet products that contribute to low environmental impact and low energy consumption in our customer?s processes. The presentation will focus on the pelletizing process. It will describe both how we have attempted to decrease the generation of unwanted components in the process gas, and how we have tested or evaluated equipment for external gas cleaning. We will discuss and give examples from recent and on-going efforts and outline some of the future challenges we see, to meet our own environmental standards and also the tough demands imposed by EU and national legislation, while striving to boost production.

May 1, 2011

By Nic Slatalla

Resin anchored rock bolts are an effective tool to control the deformation of an underground opening because they combine high support capacity with fast installation. However, there are still numerous shortcomings concerning the understanding and interaction of the system bolt-resin-rock. Field and laboratory test series have been conducted for evaluating the load capacity and bond strength of resin grouted rock bolts in different host rocks under axial load. This paper describes that the behavior and shear strength of the system bolt-resin-rock depends on the rock type and discusses a simple correlation between peak shear strength and shear stiffness in the ratio 1:1000 which may moreover be helpful for estimating rock bolt capacity after installation.

Jan 1, 2006

In this paper a numerical formulation is presented for determination of the axial load along a cable bolt for a prescribed distribution of rock mass displacement. Results using the program CABLE indicate that during excavation, the load distribution that develops along an untensioned fully grouted cable bolt depends on three main factors: (i) the properties of the cable itself, (ii) the shear force that develops due to bond at the cable-grout interface (i.e. bond stiffness), and (iii) the distribution of rock mass displacement along the cable bolt length. In general, the effect of low modulus rock and mining induced stress decreases in reducing bond strength as determined from short embedment length tests, is reflected in the development of axial loads significantly less than the ultimate tensile capacity even for long cable bolts. However, the load distribution is also dependent on the deformation distribution in the reinforced rock mass. Higher cable bolt loads will be developed for a rock mass that behaves as a discontinuum with deformation concentrated on a few fractures, than for one which behaves as a continuum, either due to a total lack of fractures or a very high fracture density. This result suggests that the stiffness of a fully grouted cable bolt is not simply a characteristic of the bolt and grout used, but also of the deformation behavior of the ground. In other words, the same combination of bolt and grout will be stiffer if the rock behaves as a discontinuum than if it behaves as a continuum. This paper also explains the laboratory test programme used to determine the constitutive behavior of the Garford bulb and Nutcase cables bolts. Details of the test setup as well as the obtained results are summarized and discussed.

Jan 1, 1996

By Jorj O. Osterberg

Until ten years ago, the largest load tests on drilled shafts (bored piles) were about 3,000 tons (27MN). These tests were made with kentledge (large weights, usually concrete blocks) stacked up as a reaction to the applied downward load of a hydraulic jack. In some cases, the jack load is resisted by a load frame held down by piles or anchors connected to the frame. When the test loads exceed 3,000 tons (27MN), these methods become cumbersome expensive and time consuming. The Osterberg (O-cell) test method does not require any reaction load. It has become the only cost effective method for static load testing of high capacity shafts. Over 650 load tests have been performed with this method, 86 of which were over 3,000 tons (27 MN) and 40 over 5,000 tons (44 MN), and the largest test load was 17,000 tons (150 MN). Tests have been made on sands below the water table, shafts ending in rock sockets, and cemented sands and gravels. Test results and details for selected load tests are discussed.

Jan 1, 2002

By David E. Thompson

This paper describes the full-scale field load testing of three deep foundation units using the Osterberg Load Cell. The load tests were completed on three separate projects, two in Massachusetts and one in New York. The Massachusetts projects involved the load testing of two 18-inch O.D. concrete-filled steel pipe piles over water for railroad bridge reconstruction projects in Revere and Saugus/Lynn. The New York project involved the load testing of a 24-inch diameter drilled shaft socketed into sandstone on land for a building foundation in Rochester. The 18-inch O.D. piles were loaded to failure at jack pressures of 142 to 215 tons. The drilled shaft was loaded to failure at jack pressures of approximately 450 tons. The loading testing procedure is described and the results of the three tests are presented. The advantages and disadvantages of the Osterberg load cell for load testing of deep foundations are discussed.

Jan 1, 1989

By Drew Floyd

Five full-scale pile load tests were performed on pairs of PZ-22 sheet piles installed with a vibratory pile driving hammer. The sheet piling was installed in several locations in soil generally consisting of miscellaneous granular fills overlying soft organic silts, inorganic silt interbedded with sands and gravels, very dense glacial till and shale bedrock. The test program also included the use of tip tell tales to determine what capacity could be attributed to tip resistance and skin friction. During the design phase of the project, it was assumed that the capacity of the sheet piles driven with the vibratory hammer could be correlated with the rate of penetration. The correlation between vertical capacity and rate of penetration would be used as a basis for determination of a driving criteria from driving the production sheet piling. The sheet piling load tests demonstrated that it was not possible to correlate the capacity of sheet piling driven with a vibratory hammer and the rate of penetration. It was also demonstrated that the capacity of the sheet piles was directly related to the density of the soil at or just below the tip. The results also tend to agree with empirical equations provided by Meyerhof (1976).

Jan 1, 1989

By Rolf Katzenbach

Construction of drilled shaft foundations with the use of hydraulic oscillators and rotators to install temporary casing over the full depth of the shaft is described. The equipment and techniques were developed in the 1960?s in Germany and full-depth casing is now the predominant method of construction in Europe. Its use in North America is increasing. This paper presents an overview of full-depth casing methods and a summary of available load test data evaluated by the authors to compare the load transfer and capacity performance of shafts installed by various construction methods. Results demonstrate that load transfer and capacity of full-depth casing shafts are equal to or exceed that of shafts constructed by dry or slurry methods and that measured capacities are consistent with generally accepted design equations. The principal advantage of full-depth casing methods over other installation techniques is that the risk of defects in the shaft is minimized. Casing is able to penetrate into the ground under any geologic or groundwater condition when this technique is applied. Potential delays and cost overruns can thus be avoided and a safe, economical foundation element is created.

Jan 1, 2007

By Mark K. Larson

Calibration of LaModel for deep coal mines begins with adjustment of overburden stiffness for load transfer distance. This calibration determines whether mining induced stresses are concentrated in the immediate abutment of the gob, or spread over a wider area. In the absence of site information, an empirically-based estimate is often used. Where data is available, a recommended calibration procedure can be followed, as is done in this case study at a deep western longwall mine, with minor modifications and extensions. In this case, data sources included borehole pressure cells, flatjacks installed in series with support Cans, and observed changes in ground conditions. Calibration was based on the first detection of mining-induced stress from the advancing longwall. Detection was found to depend on the type and sensitivity of measurement. Borehole pressure cell data with a 20-psi-increase detection threshold were chosen as the standard, in accord with data used in deriving empirical relationships. Application of this standard produced a load transfer distance estimate roughly four times the empirical relationship developed by Peng and Chiang (1984). This is a significant deviation with important implications for panel design at this site. Data from flatjacks, ground condition observations, and borehole pressure cells with higher threshold values, were tightly clustered and show load transfer distances from two to four times empirical guidance. Ratios between various measurements can be used to adjust measurements to the standard (although they may depend on mine geology). Once established, ratios can be used to adjust estimates, say from support flatjacks or ground observations, to the standard, where borehole pressure cell data is not available.`

Jan 1, 2012

By M. M. D. S. Vemba

Paper written on project work carried out in partial fulfilment of B.Sc. Eng (Mining Engineering) degree Engineering refers to the application of mathematics and other sciences to logically develop solutions to problems. However, in opencast mining, due to the randomness of operations, the use of mathematics is often neglected. Instead, practices that have proven successful elsewhere tend to apply. At the other end of the scale, mathematical models have been developed to identify and quantify all the operational parameters involved in the loading and haulage of ore. These are then used to optimize the operation. Optimization in this context, refers to the reduction of cost through effective utilization of the available time and resources. Considering these mathematical models, the loading and transport system at SMC (Catoca Mining Society) will be assessed with a view to its optimization. The discussion will be introduced by considering the mine background and other general information, which will highlight the main operational variables.

Jan 1, 2004

By Emil Szaks

[A great number of papers have been presented at various Engineering Society meetings on the Unit Train subject. Moat are descriptions of facilities that have been constructed or are abort to be built. Many describe the facility as being the World's fastest, newest, largest, incorporating the latest technology and so forth, Many are duplications of installations that have been recently constructed, sort of carbon copies but perhaps arranged differently. The trend has been to incorporate loop tracks, rotary dumpers, indexers and, of course, the snivel coupler equipped unit train. How that the energy crisis has increased the use of coal, there has been a tremendous Increase in applications for permits to construct rail to river coal loading facilities. This paper is different. It does not describe any single existing facility, but is given to alert prospective terminal owners and engineers that there are items that require considerable study and evaluation beside merely selecting an indexer, car dumper, stacker, ship or berg loader and so on. An important item is the selection of the railway car which in turn can affect the selection of the method of loading and unloading. Let us list a few of the items that should be considered and discuss the areas that require examination:]

Jan 1, 1979

By A. M. Esteves

This paper offers an overview of local content policies and practice in the mining sector. Specifically, the paper aims to answer the question of how national and regional governments, industry and civil society can work together to seek an optimal outcome while pursuing their diverse objectives. The paper begins by defining local content and its scope at the subnational level. Specific recommendations for the design of local content policies to mitigate social, economic and governance risks are developed. The document then offers some recommendations regarding the role of partners in design, implementation, monitoring, and enforcement of local content policies.

Aug 1, 2013

By A. Atta-Quayson

Since 2012, Ghana has been implementing local procurement regulations in the mining sector to broaden and deepen linkages between mining and other sectors of the economy. The regulations have been implemented in collaboration with the mining industry. This paper offers an in-depth analysis of how the local procurement regulations and related initiatives have been implemented so far. Primary data gathered with semi-structured interviews and secondary sources of data indicate a steady improvement in both in-country procurement and local manufacturing of inputs for the mining industry. There are, however, some challenges relating to tariff structure and support (financial and technical) for local suppliers and manufacturers to meet high standards and demands of the mining industry. This calls for a well-thought-out strategy and programme of activities to sustain and improve on progress made.

Feb 2, 2022

ARIZONA Established July 10, 1915 ROBERT W. THOMAS. Chairman ROBERT W. HUGHES, Vice-Chairman HUBERT O. WOODS, Secretary-Treasurer American Smelting & Refining Co., Hayden, Ariz. LYLE BARKER M. G. FOWLER RICHARD BRITTAIN M: C. HENRIE B. S. BUTLER F. D. 1. HONEYMAN T. G. CHAPMAN J. E. LANNING C. H. COLE A. MENDELSOHN G. C. DAVIS BRENT N. RICHARD E. Ii. DENTZER C. F. WILLIS

Jan 1, 1943

By Tiebao Yang

In high pressure die casting processes, a die plays a critical role in removing heat from the molten metal during the cavity filling and solidification stages. Proper control of die temperature is essential for producing superior quality components and yielding high production rates. This paper proposes a local temperature control scheme for die thermal management based on a computerized intelligent real-time monitoring and control system (IRMCS). In this scheme, cooling water lines are controlled by a pump and solenoid valves. A controller is designed according to the law of die temperature fluctuations. The results obtained from the experiments carried out on a laboratory die casting process simulator indicate that the controller can limit the local die insert temperatures in a given band. Hence, the desired thermal pattern of the die insert becomes achievable.

Jan 1, 2006

By F. A. Guo

Ultrafine-grained surface layers were obtained by surface mechanical attrition treatment (SMAT) in copper and titanium samples. The thermal properties of the deformed layers were characterized using a scanning thermal microscopy (SThM) that allows thermal conductivity to be mapped down to the submicrometer scale. A theoretical approach, based on this investigation, was used to calculate the heat flow from the probe tip to the sample and then estimate the thermal conductivities at different scanning positions. Experimental results and theoretical calculation demonstrate that SThM can be used as a powerful tool for the thermal property and microstructural analysis of ultrafine-grained microstructures.

Jan 1, 2006

By Geoffrey C. Hebner

Augered, cast-in-place piles (ACIP) have become a very common foundation type in Atlanta and the Southern Piedmont Province as well as much of the United States in the past 20 years. Prior to the introduction of ACIP foundations in Atlanta, the most common deep foundation type was Raymond piles. Raymond piles are basically a driven, thin-walled step-tapered steel pile filled with concrete. Drilled piers were also relatively common and continue to be used, particularly in shallow bedrock or high column load situations. Driven piles, including pipes, H-sections, and timber piles were previously common with working loads typically in the 30 to 50-ton range. Initially, ACIP foundations had similar allowable capacities, however, over time improvements in installation techniques and equipment have resulted in an increase in allowable ACIP capacities. Correspondingly, they have become a more cost-effective and trusted foundation for geotechnical and structural engineers. Over the next several decades many other deep foundation alternatives began to lose popularity. ACIP are one of the predominant deep foundations in Atlanta and the Southern Piedmont today. Although ACIP foundations have widespread popularity in the private sector, they have not been readily accepted currently by government transportation agencies. ACIP may be used by some of the smaller municipalities, but to the author's knowledge, have not been used with regularity by larger, state agencies.

Jan 1, 2003

A new method, localized uniform conditioning (LUC), was proposed in 2006 for modelling grades of small blocks of ore when data spacing is too broad for their accurate modelling by the linear regression based techniques, such as kriging (Abzalov, 2006). It represents a modified uniform conditioning (UC) technique that calculates the grade distribution functions for the large panels. LUC uses partitioning of the panels onto the small blocks and then ranks them in increasing order of grade. Based on the block ranks, a single grade value can be deduced for each block from the UC model of the gradetonnage relationships of the corresponding panel. After being first presented in 2006, the LUC method has been implemented in ISATIS© (commercial software) and became one of the common approaches for grade estimation when data spacing is broad in comparison with the estimated block size. Several years of study on the LUC method and its application to different geological environments, have allowed identification of the strengths and weaknesses of the method, which are as follows: ? The method produces accurate grade-tonnage functions, which are in a good accordance with a volume-variance relationship principles ? An initial ranking of the selective mining unit (SMU) blocks can be made by direct kriging from the sparse data grid. Therefore, the LUC method can be particularly useful at the early stages of exploration and mining project evaluations when sparsely distributed data is often the only available information ? Accuracy of the local estimation depends on the SMU ranking techniques. When ranking performed by direct kriging of the SMU blocks their spatial distribution is approximate. When the variogram of the studied variable is characterized by a large nugget effect, the block ranks produced by kriging can significantly differ from their ?true? distribution ? Block ranking can be improved using auxiliary data, either geophysical or geochemical. This allows use of the LUC method for integrating different data sets. In particular, LUC can be used for grade control in open pits by integrating resource definition data (e.g. drill-hole assays) and blast-hole assays. The latter are used for the block ranking.

Jan 1, 2014

By T de Wit, S Meyer

The location of seismic events in mines is traditionally calculated based on the arrival times of P- and S-waves for a given velocity model (homogeneous or heterogeneous). This technique is successful when the sources of seismic events are sudden and localised (eg episodes of fracturing in solid rock or dynamic slip along a plane of weakness) and thus the radiated seismic waves have clear arrivals. In massive mining operations such as block caves, strong seismic signals often originate from the movement of loose rocks on the perimeter of the fracture zone. These signals are easily recordable but do not contain easily identifiable direct P- and S-waves, making the estimation of location through traditional methods more complicated. This problem has been approached by using a ‘brightness’ location method that estimates the origin of seismic waves based on travel times of envelopes of seismic energy. This tool is extended to be applicable in a heterogeneous velocity environment that now accounts for the presence of a cave or other strong velocity perturbations. The suggested method is particularly important when caving occurs in low-stress environments (eg close to the surface).CITATION:Meyer, S and de Wit, T, 2016. Location of seismic events associated with caving using brightness method, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 225–236 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By D. B. Rebuli

Seismic networks in deep gold mines of South Africa are often planar owing to the tabular geometry of the orebody and, therefore, the mining infrastructure. Consequently, seismic event locations are poorly constrained in the direction perpendicular to the reef plane, and symmetrical locations above and below the reef plane may fit the observed data equally well. This problem may be resolved in situations where the strata above and below the reef plane have significantly different seismic velocities, which is the case for the Ventersdorp Contact Reef at Kusasalethu mine (previously Elandskraal, the amalgamation of Deelkraal and Elandsrand). A location method using a layered location model that takes into account the velocity contrast between the layers was tested. Observed direct- and head-waves were used to determine the velocity bounds of the P-wave velocities in the two-layer model. The data-set was also used to find the best P- and S-wave velocities for the two layers by grid searching over a range of velocities and minimizing the sum of the travel-time residuals. The results from the grid search and those from the calibration of velocities using direct- and head-waves give similar P-wave velocities for each of the two layers. A second set of seismic events was then relocated with this layered model and locations closer to reef were found. This simple layered location method goes some way to reduce the reefperpendicular location errors for Kusasalethu mine in particular. Keywords mine seismology, velocity model, location methods.

Jun 1, 2013

By R. H. Winn

A method for the selection of the most suitable corrosion inhibitor for a particular system is given. The method involves the evaluation of surface passivity by means of copper ion displacement after the metal surface has been subjected to the corrosive atmosphere. The application of the method to the selection of suitable inhibitors for use in producing wells is described. Correlation with recognized laboratory tests has beet1 found to be good within the limitations of the test. The use of the test to evaluate inhibitor persistencc is described. INTRODUCTION Corrosion as it is associated with the industry shows wide variations in its qualitative as well as its quantitative aspects. This complicates the work of the corrosion engineer. In the past few years the efforts of the corrosion engineer have been further taxed by the large numbers of products being marketed as corrosion inhibitors by various manufacturers. These products are submitted to him together with a limited amount of data to support their use as inhibitors. The data are usually authentic and reliable yet all too often when these products are applied to an actual corrosive system the results are disappointing due to the ineffectiveness of the inhibitor and the corrosive system. The corrosion engineer must select a comparatively limited number of inhibitors for field trial from the large number available. The selection is usually made on the basis of a standardized laboratory test such as that adopted by the National Association of Corrosion Engineers or by field experience in an area; however, testing of this type is discouraging on large numbers of compounds, particularly in view of the specificity of environment. It has been an object of this work to devise a method which will allow the corrosion engineer to select the best inhibitor for a specific environment under field conditions. The test would of necessity be rapid and inexpensive. It would preferably eliminate the need for expensive and delicate instruments. STATEMENT OF THEORY The test as developed makes use of the fact that metal ions will be displaced from solution by metals having a more positive electrode potential. Thus, if an active iron surface is exposed to a solution of a copper salt, free copper will plate spontaneously on the iron surface as it is displaced from the salt solution by iron ions. If the iron surface is passified, as by coating with an insulating-type organic corrosion inhibitor, it is no longer capable of displacing the copper ions due to its own limited ionization. The result will be a change in the amount of copper plated upon exposure to a neutral copper salt solution. In practice it has been found possible to measure the magnitude of the alteration of the cell potential by determining the copper deposited on a standard iron surface under controlled conditions. This means that, as the film builds up, the resulting shift in the electrode potential tends to cause the iron surface to act more like a noble metal, resulting in a reduction in the cell potential to a point that copper will no longer plate spontaneously. Obviously, the salts of other metals such as silver, gold or platinum might be used for this operation; however, copper was selected because of the color difference of the plate, the comparatively low cost of copper salts and the ease of evaluation of the plated copper. Furthermore, its high cell potential provides a substantial driving energy. The determination of the copper is readily done colorimetrically by dissolving it in 5 per cent ammonium hydroxide solution containing 2 per cent potassium per-sulfate. The blue color of the copper ammonic complex ion so developed may be compared with standards prepared by dissolving known quantities of copper powder in the same reagent. In routine screening it is seldom desirable to determine the amount of copper plated. It is usually more important to determine the concentration of inhibitor required to prevent the plating of copper.