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By T. J. Neil, C. B. Manula, O&apos

This paper describes a simulation model developed to analyze truck haulage problems as they are found in the open pit mining and construction industries. The model, using a computer, cycles trucks between their assigned loading and discharge points over a measured haulage route. Required parameters for model operation include the number and type of operating trucks and loading units, maximum truck acceleration and velocity, a realistic vehicular deceleration rate, and the ratio of ore to total material loaded at each origin. Equipment performance characteristics, system profile characteristics, and service time distributions are also included. Records are kept of all waiting times at the loading and discharge points and of any truck interference on the haulroads (moving queues), and a current journal of ore and waste production is maintained. In the pursuit of reduced truck haulage costs, management is confronted with three particular problems in truck and shovel mines. 1) What is the best assignment of trucks to shovels in the system? 2) If new equipment is needed, which new shovels and trucks will operate most effectively in the system? 3) Are any physical changes in the haulage layout warranted to increase productivity? For small open-pit mines the answers to these questions may be obvious. However, for larger operations complex problems are encountered with production and system configuration relationships usually being unknown. The mining simulator discussed here was developed to aid management in evaluating alternative pit-haulage schemes to reduce the risk involved in the selection and assignment of equipment in open-pit truck and shovel mining systems. There are two fundamental differences between this model and other truck haulage simulators: one is a difference of degree, the other a difference of kind. This model can simulate more complex systems than previous models by allowing transportation of material from multiple mine faces to multiple mine destinations and by being readily adaptable to a wide variety of mine layouts. The second difference that characterizes the model is the standard simulation of truck movements. This technique enables each vehicle to perform according to its mechanical capabilities and the physical profile of the haul road. Among the similarities between other truck haulage simulators and this model are the recognition of the probabilistic nature of certain service times in the system and the use of a digital computer to operate the model. The computer inherits the staggering computational and bookkeeping work loads and provides a means for compressing the time scale by allowing several days' operations to be simulated in a matter of minutes. DISTRIBUTION SYSTEM Basic aspects of the system analyzed here may be brought into focus by referring to Fig. 1, a schematic of the typical open pit truck-shovel operation programmed into the simulation model. A single stage materials handling scheme is employed to transport both ore and waste. Loaded trucks are directed to a crusher or stockpile if ore is being mined, while overburden is conveyed to a waste dump. Each shovel has a given number of assigned trucks and has two associated haulage routes, one for waste and one for ore. Up to 5 shovels and as many as 10 trucks per shovel (or a total of 50 trucks) can be operated in the model. Essentially the model, using a computer, cycles trucks between their assigned shovels and the proper discharge points over measured haulage routes. Required input parameters for model operation include the number of shifts to be simulated, operating time per shift, number and type of operating trucks and shovels, maximum truck acceleration and velocity, a realistic vehicular deceleration rate, and the ratio of ore to total material loaded at each shovel. Equipment performance characteristics, system profile characteristics, and service time distributions are

Jan 1, 1968

By Anand Bhagwat

Surface control can prevent the falls of ground between primary roof support systems and rib support. Using existing industrial products, and adopting them for mining applications, has historically attained surface control in underground mining. However, the latest innovative solution, a revolutionary wire mesh product, is designed specifically for underground mining applications jointly by Bekaert and Orica. This knotted wire mesh, FlexKnot? 2500 and FlexKnot? 3500, uses smaller gauge, higher tensile strength wires, than a chain link fence or welded wire mesh. The higher tensile wire enables the mesh to achieve greater ultimate load-bearing capacity, with significantly lower overall weight. Test results, obtained at the National Institute for Occupational Safety & Health (NIOSH) Mine Roof Simulator facility, illustrate the comparisons of the new FlexKnot with traditional 8- and 10-gauge welded steel mesh. The FlexKnot is superior in deflection, load-bearing capacity, and stiffness?categories that are critical in achieving safer surface control. It also offers enhanced corrosion resistance because of the galvanized coating applied on the individual wires prior to the knotting process. Case studies from underground coal mine installations confirm that FlexKnot has the ability to significantly reduce installation cycle time and to minimize use and repetitive manual handling of individual mesh panels. An added advantage is the ability to supply FlexKnot in rolls for quick and easy handling for either rib or roof support application. When using rolls, the bolter can install the entire roll with one continuous forward motion, unlike the wasteful back and forth travel for mesh panel.

Jan 1, 2014

By E. C. Winegartner, A. A. Ubbens

The company attempting to sell coal to large utility plants is faced with a confusing array of quality parameters and specifications which are often poorly understood by both the utility company and coal supplier. While these specifications are placed on the coal by the utility company, many of them originate with the boiler manufacturer who must guarantee that his product will perform satisfactorily on the design coal. A proper understanding of these parameters by both the coal supplier and utility company can lead to a better understanding of their mutual problem. This paper brings together most of the parameters in common use today and attempts to show what the parameters mean to the boiler designer, particularly in the area of boiler slagging and fouling.

Jan 1, 1977

By E. Allen Wendt

It is both a great pleasure and something of a challenge for me to have this opportunity to address a gathering encompassing such a wealth of expertise in the minerals field, It is particularly challenging because I have been asked to turn your attention from the relatively glamorous subjects of gold and money to the more mundane questions of our International commodity policy and the place of buffer stocks in that policy. However, these questions may be of more immediate importance for our economic interests at home and Abroad. I can testify that the problems affecting international commodity markets and the possibility of international action To resolve those problems are matters of real concern to Washington as well as to your industries,

Jan 1, 1978

By J. L. Jambor, H. W. Nesbitt

Oxidative dissolution of pyrrhotite and pyrite is largely responsible for the sulfate-rich waters of the vadose zone in the Waite Amulet tailings. Although the shallowest of the sulfate-rich waters are of the Fe-SO4 type, they change to Mg-SO4-type, near-neutral waters within 1-2 m of the tailings surface. Phyllosilicates and amphiboles are the only minerals present in sufficient quantity to ameliorate the amount of acidity produced. X-ray diffraction and microscopic studies of bulk sample indicate that quartz, chlorite, talc, amphiboles, magnetite, albite, and micas are the major and minor non-sulfide minerals, but their variations with depth do not give clear indications of depletion in the vadose zone. Mineralogical and bulk chemical compositions of the tailings confirm that Fe2O 3 has accumulated in large quantity in the vadose zone, with the Fe having been derived from Fe sulfides. When the effect of Fe2O3 is accounted for, the bulk compositions suggest that SiO2 is slightly more abundant in the vadose zone than in the saturated zone. This may be the result of residual enrichment of siliceous minerals such as quartz and albite in the vadose zone. Weathering of the tailings since the cessation of deposition in 1962 has resulted in a well-defined zone of sulfide depletion and secondary sulfate-mineral development. Although some silicate dissolution is indicated by pore-water compositions, the role of silicates in providing neutralization seems to have been minimal. The contribution by silicate minerals in laboratory tests of neutralization potential may be excessive relative to that in natural settings.

Jan 1, 1999

By Tiezheng Li

Keywords: Laminate Composites; Mechanical Behavior; Damage Evolution The mechanical performance of Ti-6-4-Al3Ti metal-intermetallic laminate (MIL) composites synthesized by a reactive foil sintering technique was evaluated. Crack morphology of untested Ti-6-4-Al3Ti MIL composites has been characterized by optical microscopy. Mechanical tests were performed on Ti-Al3Ti metal-intermetallic laminate (MIL) composites and pure Al3Ti, and the principal mechanisms of damage initiation and accumulation were identified experimentally. The elastic properties and anisotropy of the laminates were calculated and successfully compared with Resonant Ultrasonic Spectroscopy (RUS) measurements. The effect of residual stress on the fracture toughness of the Ti-6-4-Al3Ti MIL composites was analyzed.

Jan 1, 2005

By N. Morrison, E. J. Rogans, A. J. Macintosh, N. Schoeman

"The design of carbon-in-pulp (CIP), and carbon-in-leach (CIL) adsorption circuits has essentially remained unchanged since the early days of the carbon process for gold recovery. For CIP circuit the pulp residence time is traditionally fixed at one hour per contactor with a carbon concentration of between 15 and 20 grams per litre, and the counter current carbon transfer rates are in the region of 15% pulp recycle. For CIL, the pulp residence time is usually three hours per contact or, with lower carbon concentrations ( 5 to 10 grams per litre).The drawbacks of using the counter current CIP/CIL adsorption circuits are discussed using modeling developed for CIP/CIL plant design. Counter current CIP/CIL, circuits are then compared with the carousel method of adsorption circuit design.The use of equipment suitable for the carousel approach is discussed which is, the AAC cylindrical and pumping (MPS) screens, the AAC pump-cell plant and launder designs.Finally, two plants at the Vaal Reefs Gold Mining and Exploration Company that use carousel adsorption circuits, namely the Vaal Reefs No. 1 Gold Plant, a CIL plant with stepped contactors, and the Vaal Reefs No. 2 Gold Plant, a CIP using a very short residence time (AAC pump-cell) are discussed."

Jan 1, 1998

By A. J. Erickson, W. W. Atkinson

Concepts developed in a geologic data recording system at the Victoria, Nevada breccia pipe-skarn copper mine, are not fundamentally new, but represents expansion of earlier ideas. The basic philosophy is that a high quality geologic data base is necessary and should be complete, clear, standardized, neat, quantitative, and readily useable. It may be multi-colored or simply black and white. Graphic, descriptive and quantitative recording of data is essential. A format for core logging is presented and discussed, as well as a mu1tiple overlay system for recording data gathered in surface mapping.

Jan 1, 1984

By John O. Galloway

"The year 1947 was a momentous one in the history of the petroleum industry in Canada. It was in that year that Imperial Oil Limited made its discovery at Leduc, the forerunner of other discoveries, large and small, and the spark wl1ich started a most intensive exploration and development programme there.If, to use boxing parlance, Leduc was the first blow of a one-two combination which left doubting Thomases groggy, then Redwater was the number two blow which achieved the knockout. The oil industry's exploration leaders did about-face without delay and the rush of oil operators of all classifications to western Canada began. It is still continuing, and the influx of capital which the operators have brought in and are bringing in has a bouyant effect upon the over-all economy. The boom is on, but it is a sound one, and it is difficult to conceive that it will have anything but the most beneficial effect on Canada, and particularly western Canada.The petroleum industry is an important segment of the general economy. Its activities call for tremendous amounts of capital; its employees are well paid; it is a large customer for a wide range of products of other industries; its commodities are essential to the citizens and the nation.The industry is carried on by highly aggressive and independent groups and individuals, of which a small minority are integrated while the majority are relatively small operators engaged in only one or two phases of the business. Competition is the rule and, since the nature of the business is mass production, the industry is faced from time to time with serious problems, many of which are peculiar to it."

Jan 1, 1950

By Tom Short, Paul Kunze

In this paper, the authors describe major changes in drilling and blasting methods instituted at the Zortman And Landusky Mining Company Properties to maintain the viability of these north central Montana surface mines in the present period of depressed precious metal prices. The authors explain how improved drilling procedures minimized problems due to uneven benches and floors. They also describe changes in explosives loading and delay blasting techniques which improved fragmentation, thus increasing metal recovery from heap leaching. Quantities were increased substantially and a new bulk explosives loading system was placed in service with a special down-the-hole bulk loading truck and storage facilities for bulk ANFO and bulk emulsion. At the same time, drill patterns were expanded by nearly 40%. The authors also describe a new technique of using explosives to selectively cast waste and ore in different directions so as to reduce the cost of separating the ore.

Jan 1, 1986

By C. H. Mathewson

MICROSCOPIC rnetallography has been exploited quite well enough to bring about a very general understanding that the typical metal or alloy is composed of minute crystalline particles blended into a coherent microstructural mosaic. One does not have to be a specialist in metallography to realize that the properties of such an aggregate are essentially a summation in appropriate form of individual effects derived from the shape, size, placement or orientation and cohesive characteristics of the component particles. It is clearly of great importance to consider the various forms of discontinuity which may occur at the boundaries between these crystalline particles. When a number of particles each possessing the same orderly arrangement of atoms are brought together into a close-fitting system of purely haphazard contacts, not unlike a handful of snowflakes compacted into a snowball, the particles are said to possess random orientation. There are no generally accepted views concerning the arrangement of the atomis or the constitutional reaction between atoms where one crystal meets another, but these contact regions are characterized by strength rather than weakness and it is customary to require the presence of many rather than few boundaries in preparing metal for useful service. Under certain circumstances all of the particles in a metal may be nearly alike in orientation. Other general tendencies of orientation may be associated with particular forms of mechanical and thermal treatment. In contrast with these cases of fortuitous or statistical diversity of orientation, we often find adjacent particles united along a plane which possesses a grouping of atoms belonging equally well to both structures. This, of course, determines a fixed relationship between the two orientations and it is always possible to derive one from the other by some form of rotation or reflection prescribed by the symmetry of the crystal structure under consideration. Particles united in this manner are known as twin crystals although the term refers to the form of association rather than the number of individuals concerned.

By Jack Washburn, E. R. Parker

Kinking in zinc single-crystal tension specimens was observed under conditions of low stress and high temperature. Kinking is discussed in relation to other plastic bending phenomena on the basis of dislocation theory. Experiments on the stress-induced motion of small angle boundaries are reported. KINKING was first reported by Orowan1 as a new deformation mechanism. He observed the phenomenon in cadmium single crystals loaded in compression. Glide lamellae in a local region of the rod were observed to snap over suddenly to a tilted position, resulting in a sudden shortening of the specimen. Between the tilted portion and the rest of the crystal there were fairly sharp boundaries, with the slip plane assuming approximately mirror image positions on opposite sides of these boundaries. Orowan considered the boundaries to be regions where dislocations had concentrated. Hess and Barrett' observed the formation of kinks in critically oriented zinc compression specimens. It was found that the sudden snapping over of the tilted region was not an essential part of the kinking phenomenon but rather was associated with the method of loading. Kinking was explained on the basis of the accepted mechanisms of slip and flexural glide. It was also suggested that a kink can be considered as a special type of deformation band. During a recent investigation of the effect of surface condition on creep of zinc single crystals," a similar phenomenon was observed in crystals which were loaded in tension. The specimens were 0.4 in. diam cylindrical rods with a free length of 4 in. between end connections. All of the crystals were tested at a constant load. adjusted to give an extension rate of approximately 0.05 pct per hr. Kinking, as shown in Fig. 1, occurred in some of the tests performed at temperatures above 200°C. Kinking was observed in specimens varying widely in initial orientation, scattering about a 45" angle between the slip plane and the specimen axis. The condition leading to kinking in tension appeared to be non-uniform distribution of flow along the gage length combined with the restraint imposed by the tensile load. At low temperatures and fast strain rates, the distribution of strain throughout the midsection of tension specimens was generally quite uniform; therefore, bend planes developed only near the ends as described by Miller.4 However, at high temperatures under creep conditions it was difficult to obtain specimens in which the distribution of flow was uniform. Some of the factors which may have caused differences in flow stress along the length of the crystals are: Nonuniform distribution of impurities, accidents of growth (lineage structure), slight bending or other damage during handling, surface conditions, and strain-aging characteristics due to dissolved nitrogen." Plastic flow, once started in a local region, often continued to a relatively large strain before other parts of the gage length became active. Under these conditions a series of kinks, such as those in Fig. 1, were produced. Fig. 2 illustrates how a nonuniform distribution of slip produces bending moments which- are responsible for kink formation. If no plastic bending were to occur while the rod extended by pure slip in two separate sections of the rod, it would assume a shape such as that in Fig. 2a. A specimen having this shape and being subjected to a tension load would have concentrations of stress at the concave surfaces C and lower than average stress would exist at the convex surfaces D. Therefore a bending moment is superimposed on the average stress in the regions between C and D. The positions of potential bend planes under these conditions are shown as dotted lines. Actually no such shape as Fig. 2a develops because plastic bending in the region C-D occurs simultaneously with pure slip in the intervening regions. The observed structure of a tension kink is indicated by Fig. 2b. Perhaps the best approach to an understanding of kinking as well as other related plastic bending phenomena, such as the bend planes discussed by Miller,' cell formation studied by Wood et al.,6 and polygonization,7 is consideration of the dislocation model of a bent lattice. Current theories of the slip process postulate generation or multiplication of dislocations at certain lattice imperfections. The mechanism proposed by Frank and Read8 results in continuous generation of concentric dislocation loops which spread out

Jan 1, 1953

By D. Fodor

In Romania, there are significant lignite and brown coal reserves hosted by different regions of the country. The most important lignite bearing zone of the country situated in the North ? West part of Oltenia region and which covers a surface area of 2,500 km2 and host a total reserve of 3.0 billion tons of lignite, of which more than 95% can be exploited by open cast method. The paper deals with the existing geological and mining conditions of the zone , the distribution by mining basins and exploitation perimeters, the open cast working technologies and the economic outcomes obtained throughout the time. Years ago, for the improvement of the economic situation as a whole and in each unit, a large production reorganization, technology update and modernization process was started up. There are described the rehabilitation measures of the technological lines and modernization of the equipments of the production flow-sheet, measures developed at present, too and which will still continue in future. There are mentioned the equipments considered, the components under modernization and the economic outcomes obtained so far. At the end of the paper there are presented the future actions for the equipment modernization and perspectives of the lignite deposit exploitation to meet the national economy requirements of solid fuels.

Aug 1, 2013

By Ronald E. Triplett, George K. Burke, Bernard H. Voor

To accommodate larger double-stack rail cars through a tunnel, the existing active tracks were to be lowered. The tunnel is an elliptical, horseshoe-shape with concrete base support, removal of which would jeopardize the tunnel integrity, particularly since the soils beneath part of the tunnel floor included soft, saturated silt overlying rock. Grouted bar anchors combined with a SuperJet soilcrete strut replaced the existing support in situ prior to floor lowering. Close cooperation and detailed timely engineering support provided a quality project. Project design and construction, ground improvement methods, and the performance of the work are described.

Jan 1, 2001

By Fredrick L. Johnson

No mineral resources were identified during the investigation of the White Cloud-Boulder RARE II area. Only a few claims have been located in the area and only two workings were found. However, there has been considerable exploration and mining activity near the RARE II area. Sand and gravel resources are abundant but similar deposits occur closer to market areas. There are no known coal, oil, or gas deposits. Most of the RARE II area is underlain by volcanic rocks. The likeliest host rocks for metallic minerals are the metasedimentary rocks exposed in the south part of the area; there is potential for zinc and silver resources at a prospect in that part. Traces of scheelite and powellite were observed in the Kent Peak-Ryan Peak area along hair-line fractures in calcareous country rock. While no significant concentrations of the minerals were found, their presence, a northwest alignment of prospects with similar deposits, and an abundance of dikes near the deposits, suggest that the intrusive system (Summit Creek stock) exposed near the head of Little Fall Creek may extend to the northwest under the RARE II area.

Jan 1, 1983

By Waclaw Trutwin, Stanislaw Wasilewski

Application of computer-based systems for ventilation process monitoring makes it possible to widen the system functions with those connected with long-term data analysis. It allows the mine ventilation engineer to carry out necessary preventive actions. In future the wide application of computers and sophisticated expert systems together with automation equipment (like remotely controlled regulators and fans) will allow to gradually introduce minewide systems for air flow control. To achieve this goal research work is carried out using data from a mine ventilation monitoring system and methods of computer analysis of time series. With the use of digital filtering the measuring signal spectrum has been divided into three subranges components of which are important with regard to various needs of mine ventilation staff as well as to monitoring and control system functions.

Jan 1, 1991

By Manuel R. Lastra

Critical to successful dump and heap leaching for gold, silver, copper and uranium are factors such as permeability, solution delivery to the ore, and solution recovery. This paper deals with possible techniques for successful accomplishment of these three factors. New developments as well as older techniques are discussed, together with rationale for use of some techniques in reference to others. The authors hope to present a checklist so that the ideal application to individual mine situations can be achieved. This involves a discussion of the merits of each different method and the situations for most logical application. It is hoped that such discussion will broaden the geographic areas where dump and heap leaching can be applied to include greater winter cold and tropical regions of large amounts of rainfall.

Jan 1, 1984

By Engelmann. William H.

In pursuit of innovative methods to improve mining productivity, the Bureau of Mines is investigating the use of inorganic salts as drilling fluid additives for penetration enhancement. Laboratory diamond drilling tests were performed on Westerly Granite with aluminum chloride solutions and on Sioux Quartzite with aluminum nitrate and aluminum, calcium, sodium, and zirconium chloride solutions as drilling fluid additives. These drilling results were compared with the average drilling performance using distilled, deionized water on Sioux Quartzite (12 replicate tests) and Westerly Granite (3 replicate tests). Maximum in-creases in penetration per given time and bit life were obtained when drilling with zero point of charge (ZPC) concentration solutions of each additive. For Sioux Quartzite, maximum increases in penetration and bit life ranged from 96 to 115 pct and 64 to 99 pct, respectively. For Westerly Granite, maximum increases in penetration of 155 and 165 pct and bit life of 109 and 136 pct were obtained at or near ZPC aluminum chloride concentrations of quartz (7.3 x 10-7 mol/L AIC13) and alkali feldspars (1.1 to 1.5 x 10-6 mol/L AIC13), respectively. This simultaneous increase in penetration per time together with extended bit life should result in increased productivity and reduced bit costs.

Jan 1, 1987

By C. Ntsele

Stirred milling technologies have firmly established themselves in concentrator circuits as energy-efficient alternatives to tumbling ball mills. High and continued increases in electricity costs, coupled with the ever-increasing power consumption by primary grinding circuits due to declining head grades of ore-bodies, provides a compelling case for these technologies. Additionally, the ability to successfully deploy stirred milling in coarse grinding applications extends the range of use in concentrators, thus increasing the opportunity matrix for energy optimization in a flowsheet. This paper therefore details methodologies and strategies that can be applied to evaluate the optimum stirred milling solution for different concentrator applications. These methods and strategies will focus specifically on the two major stirred mill machine types; namely, gravity-induced (VERTIMILL? grinding mill and Nippion-Eirich tower mill) and fluidized (SMD, Isamill?, Knelson-Deswik mill, etc. ). Finally, case studies from circuits across industry and laboratory tests will be used to illustrate the energy benefit from the use of stirred mills.

Jan 1, 2012

By S. G. Malghan, J. P. Van Dillen

Some uranium minerals are paramagnetic and hence are amenable to concentration by high gradient magnetic separation (HGMS). This paper describes effects of the HGMS parameters-pulp velocity, field strength, matrix loading, and magnetic field gradient-on the product recovery and grade. Unsatisfactory separation of uranium minerals by HGMS is related to ore-specific properties, such as lack of liberation, fine dissemination of uranium minerals, uniform distribution of magnetic minerals throughout the ore matrix, and interference of fine-sized slimes. Experimental techniques to identify and resolve some of these problems are outlined.

Jan 1, 1984