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By P Paredes, T Leaño, D Gajardo, C Tramón, S Peñaloza

The definition of an ore handling system and its consequent layout design is of crucial importance in cave mining projects. It not only represents the main driver in the production capacity and reliability of the mining system, it is also a fundamental variable in the footprint’s development time and cost.In recent decades, load-haul-dump (LHD) tramming distance optimisation through the allocation of several orepasses inside the footprint has been the most common practice in ore handling system layout definition at Codelco’s operations. Today, the improvement of existing technology, such as higher-capacity LHDs and jaw-gyratory crushers, and intensive preconditioning techniques to improve fragmentation allow the conceptualisation of simple and highly productive ore handling system layouts for wide caving areas that avoid the complexity and high cost of developing numerous orepasses inside the footprint.The initial macroblocks of the Chuquicamata underground mine project (PMCHS) consider an ore handling system layout in which LHDs dump into orepasses located inside the footprint area. The ore is then transferred into crusher chambers located below the production level, where it is crushed by jaw crushers and then conveyed to surface. In an effort to reduce development time and costs, a new ore handling system layout for the PMCHS experimental macroblocks was engineered using improved technologies and techniques in a simpler mining system. This paper compares the new ore handling system layout for the project’s experimental macroblocks with the traditional LHD-orepass layout in terms of production capacity, reliability, development time and cost.CITATION:Paredes, P, Gajardo, D, Leaño, T, Peñaloza, S and Tramón, C, 2016. Simplifying the ore handling system through the use of current technology at Chuquicamata underground mine project, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 571–584 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By Nicol S. K, Swanson A. R

The poor flotation response of many coals has in the past been attributed to such factors as differences in rank, differences in degree of oxidation, differences in petrographic composition, or slime coatings. The present work shows that while all these factors undoubtedly influence flotation, the size distribution of the feed may override these. Evidence is presented which shows how this factor can lead to substantial losses of coarse coal (>250 µm)from a coal which would normally be considered amenable to flotation. Reasons for this loss of flotation response are suggested together with means of overcoming the problem.

Jan 1, 1978

By M. E. Hawkins

This Bureau of Mines report provides information on all of the 329 proved salt domes in the Gulf Coastal States and offshore area of the United States. It includes specific data related to location, depth to the cap rock and to the salt, storage facilities for LPG, and production of salt, sulfur, petroleum, and rock related to or associated with the dome structure in the subject area. Also included is a brief history of the salt, sulfur, and petroleum industries as related to the salt domes. Gulf Coast salt domes were the scene of the first discovery of a large deposit of rock salt in North America, the birthplace of the Frasch sulfur industry, and the location of the first large oil gushers that ushered in the modern liquid fuel age.

Jan 1, 1966

By Dan A. Brown

This paper describes a method of conducting rapid lateral loading tests of deep foundations in which the load is applied to the foundation with a time duration of less than one second. For purposes of this paper the loading is applied using a pyrotechnic loading system commonly referred to as Statnamic. However, the method should apply to any lateral loading system which produces a force time history with a loading duration of 20 msec to 1 second. The test provides a measure of the dynamic and static response of the soil/foundation system and must be evaluated as a dynamic loading. Interpretation of the test includes a simple single degree of freedom (SDOF) model which can account for the inertial effects of foundation mass, system damping, and static foundation stiffness. The results of the test measurements are compared with four case histories in which comparative static load test data are available, including pile group foundations and large diameter drilled shaft foundations.

Jan 1, 2007

By John M. Devine

The severe corrosion of equipment that is caused by the presence of hydrogen sulphide in oil and gas has been described in detail by several authors.5 Such corrosion, termed "low-temperature hydrogen sulphide corrosion", presents a somewhat different problem from the "high-temperature hydrogen sulphide corrosion" that is encountered in refinery operation and

Jan 1, 1932

By Selda Ozkan

In this study, a combination of cathodic arc physical vapor deposition (PVD) and molten salt electrolysis methods were used to obtain ZrB2 layers on AISI 304 grade stainless steel surface. Prior to boriding, steel surface was coated with metallic zirconium via cathodic arc PVD method and then the zirconium coated steel was borided by molten salt electrolysis. Well adherent, dense, ZrB2 layers are formed on the substrates. The thickness of the ZrB2 layer showed dependence on the thickness of the metallic Zr coating layer and the time of boriding. During the boriding process the alloying elements of the substrate also took part in the coating structure depending on their diffusion characteristics.

Jan 1, 2010

By C. Van der Veen

The use of the quasi static (Dutch) Cone Penetration Test (CPT) is described as a tool to predetermine the ultimate bearing capacity of the pile point. An analysis is given why a purely theoritical approach does not meet with success. A practical method is explained of extrapolating the cone resistance to predict the pile point resistance. The method has been calibrated against the result of 32 selected high standard loading tests on pile points in the Netherlands.

Jan 1, 1989

The process of pile driving disturbs the soil around the pile. The nature and magnitude of disturbance depends upon 1) the pile size, and 2) the nature of soil. Therefore, the prediction of a single pile behavior based on soil properties of undisturbed soil samples may not match its performance. Under lateral loads, the pile may loose contact with the soil near the ground surface especially in clays. The soil pile interactions are influenced the most by pile behavior in this zone. This situation further affects the tally of prediction and performance. Piles are used in groups. The zones of overlapping stress from one pile to the other both around the pile and below their tip particularly in soft soils, contribute to group effects. Empirical solutions have been developed for prediction of the pile group behavior. The group action is more involved under vibrations. Several cases of single piles and pile groups under static and dynamic loads from published records have been analysed. It has been shown that single pile test is the best source of information on the soil-pile-soil interaction effects.

Jan 1, 1989

By D. F. Scott

Seismic tomography, as used in mining, is based on the principle that highly stressed rock will demonstrate relatively higher P-wave velocities than rock under less stress. A decrease or increase in stress over time can be verified by comparing successive tomograms. Personnel at the Spokane Research Center have been investigating the use of seismic tomography to identify stress in remnant ore pillars in deep (greater than 1220 m) underground mines. In this process, three-dimensional seismic surveys are conducted in a pillar between mine levels. A sledgehammer is used to generate P-waves, which are recorded by geophones connected to a stacking signal seismograph capable of collecting and storing the P-wave data. Travel times are input into a spreadsheet, and apparent velocities are then generated and merged into imaging software. Mine workings are superimposed over apparent P-wave velocity contours to generate a final tomographic image. Results of a seismic tomographic survey at the Sunshine Mine, Kellogg, ID, indicate that low- velocity areas (low stress) are associated with mine workings and high-velocity areas (higher stress) are associated with areas where no mining has taken place. A high stress gradient was identified in an area where ground failed. From this tomographic survey, as well as four earlier surveys at other deep underground mines, a method was developed to identify relative stress in remnant ore pillars. This information is useful in making decisions about miner safety when mining such ore pillars.

Jan 1, 1996

By J. Roodt

Paper written on project work carried out in partial fulfilment of B. Eng (Metallurgical Engineering) degree This work was done to characterize the leaching of a uranium containing pulp processed by a South African producer to identify parameters that could be adjusted to increase the extraction of uranium in the existing circuit. Batch leach tests were used to characterize the leach properties and especially the influence of the oxidant concentration on the leaching achieved. It was found that relatively high extraction could be obtained even at room temperature by using a high liquid-to-solids ratio and that increasing the oxidant concentration significantly improved the leaching of the uranium minerals.

Jan 1, 2003

By L. C. IlsLey

"The use of trailing cables on cutting machines, loading machines, and similar electrically operated apparatus is recognized as a necessary adjunct to the economical operation of such units. On the other hand, such cables because of their liability to failure from being run over by cars, locomotives, and other track-operated equipment offer one of the greatest hazards - indeed, probably the worst hazard - met with in the operation and maintenance of permissible equipment. Therefore, the Bureau of Mines is seeking ways of making the use of trailing cables less hazardous.Recently the bureau conducted an extensive investigation of both concentric and duplex rubber-sheathed trailing cables at the Pittsburgh Experiment Station. The results of this investigation were published in two reports.3 4In a larger part of portable motor operations in mines a double-conductor cable can be used. The investigation already mentioned indicated that it is feasible to construct a 2-conductor cable that will stand considerable abuse, such as being run over by loaded cars or light-weight locomotives without producing dangerous arcing in the cable either from grounds or short circuits. There are conditions where more than two conductors are necessary, and in such instances it will probably be necessary to use a cable less resistant to this kind of abuse.Schedule 2C, covering the tests of electric motored equipment, was approved February, 1930. This schedule provides for performance tests on trailing cables as follows;Trailing Cable Performance: The following performance test, optional with the manufacturer, is established for determining the suitability of trailing cables for use on permissible equipment. Trailing cables that pass this test will be especially recommended for this service.The cable will be placed across the two rails of a track and a 4-wheeled 7-ton car will be run over it 50 times. The speed of the car shall be approximately 3-1/2 miles per hour and potential shall be applied to the cable during tests. The cable will be shifted in position after each passage of the car thus giving 100 places over which two wheels have passed. To warrant special recommendation of the Bureau, a cable must neither become short-circuited nor grounded either to the rails or wheels in more than 10 per cent of the 100 places.The Bureau of Mines is prepared to conduct tests as outlined in the foregoing paragraphs to determine the suitability of trailing cables for use on permissible equipment. Application for such tests should be made to the Director, Bureau of Mines, Washington, D. C. Each application should be accompanied by a check for $25.00, made payable to the Treasurer of the United States, to cover the expense of conducting the test on a given size and make of cable."

Apr 1, 1930

By T. Lindstad, V. Myrvågnes

In the production of high silicon alloys, carbonaceous materials like coal, coke, charcoal and woodchips are utilized as reducing agents. Primarily based on historical prices of charcoal compared to fossil reduction materials, the Norwegian Ferroalloy Industry has mostly been using coal and coke (char) as carbon source. The most important role of the carbonaceous material is to react with the SiO gas to produce SiC. The ability of the reduction materials to bind SiO gas can be measured and the value is recognised as the reactivity of the carbon source. This reactivity is one of the most important parameters in the smelting process in order to obtain a high yield of metal. The reactivity of the carbon materials is directly correlated to the material properties. It is known that the rank of the coal influences the SiO reactivity where low rank is beneficial. Coals of the same rank have however proven to have varying reactivity. In order to investigate how the micro-constituents of coal influence the reactivity towards SiO gas, three single seam unwashed coals of different origin which fulfil the requirements of the Norwegian Ferroalloy producers have been chosen. As the structure in the carbonized product is a function of petrographic constitution and carbonization parameters, the coals have been separated into different density fractions. The various density fractions of the same coals proved to have significantly different petrographic composition. The coals were carbonized according to a procedure simulating the conditions the coals experience when charged to an industrial furnace. Chemical-, physical- and petrographical properties of both the coals and the resultant chars have been thoroughly examined and correlated towards the SiO reactivity.

Jan 1, 2007

By J. B. Platt

Many utility fuel choices 1990-95 defied expectations, with utility decisions and coal market developments ever more closely linked. The Central Appalachian coal boom never occurred; clean-enough coal was developed in the hard-hit Midwest; Colorado-Utah coal surged; Pittsburgh seam production strengthened; utilities embraced Powder River Basin coal; and emission allowance prices collapsed. Competition drove productivity gains, but the future is not a simple repeat. Phase 2 brings fewer viable compliance options. Mega-railroad pricing has become a key risk factor -- will this be countermanded by merging utilities and power market competition? Revenue losses from vintage contracts are problematic. Uncertainty also plagues natural gas, in spite of unanimity across major forecasts, since recent experience has been so heavily influenced by the gas bubble.

Feb 24, 1997

By M. C. Bhulose

Paper written on project work carried out in partial fulfilment of B. Eng (Mining Engineering) degree The purpose of this project was to identify constraints that could occur in the current sub-decline shaft at Turffontein Shaft should an increase in production take place. Particular attention was to be paid to the transportation of men and materials and to the broken rock and ventilation capacity of the shaft. This project is an in-depth evaluation of the logistic capacity of the sub-decline system at Turffontein Shaft in order to determine by how much production can be increased in this area to replace tonnages from the vertical shaft area, where ore reserves are rapidly becoming depleted.

Jan 1, 2004

By R. L. Castro

The extraction of ore in panel caving operations also involves the coextraction of non-economic material, known as dilution. Forecasting, avoiding, and understanding the mechanics of dilution is critical to longterm planning. The models of dilution that are currently in use in panel caving operations are those by Laubscher (1994), who postulated that dilution is due to gravitational flow and depends on the height of interaction, the column height, and the draw uniformity. This paper presents a back-analysis of extraction and dilution behaviour at Codelco?s El Salvador and Andina Divisions, which use panel caving as a mining method. This analysis was conducted in order to review the existent dilution entry mechanisms and calculation methods. Three sources of dilution were identified. The first source is ?gravitational dilution?, which is due to gravitational flow and mixing as dilution migrates by gravity from a sector located above the panel under analysis. The second source of dilution is ?caving dilution?, which occurs when an air gap is formed in a large area and a sudden propagation of a hang-up occurs, inducing early ingress of waste into the production level from a level above. The third mode observed is ?lateral dilution?, which occurs when the panel is located next to an exhausted sector and the broken material enters the draw column early during draw. In the last two cases, dilution could migrate large distances horizontally. The mine data indicated that draw and caving strategy are key for long-term planning of large panel caves.

Jan 1, 2014

By H. E. Bartlett

In the operation of some flotation plants treating platinum ores it was found that there were imbalances between the inputs and outputs. The inputs and outputs were sampled as slurries and it was determined that the imbalances arose from biases in the sampling, despite the samplers having been designed according to well-established rules. The launders feeding the sample cutters, and the sample cutters themselves were redesigned using finite element analysis to model the flows. A new set of design rules were formulated. The application of a Components of Variance Analysis, to determine the variance of primary and secondary sampling and of analysis in the lab for a concentrate is presented to illustrate the need for frequent sampling of process streams.

Jan 1, 2002

By M. N. Brodie

"The ability to adjust the speed of a SAG mill offers benefits to the process and to equipment maintenance. It can be provided with some slight effect on availability ranging from somewhat enhanced to somewhat reduced, depending on the particular equipment that is used. Several techniques have been developed for monitoring the magnitude of the contained charge, and several algorithms have been used to control mill feed rate and mill speed. The various benefits and the means by which they can be realized are examined and compared. Reasons for Variable SpeedProcess RequirementsThe recovery of minerals from ore is dependent on particle size and residence time in process. Separation in a given plant is most efficient at a particular rate and a particular size (e.g., 80% minus 200 mesh). If the particle size increases, less mineral will be liberated. If the particle size is significantly reduced, the process of choice may not be able to effect separation, and power, media, and maintenance costs would be increased.If a SAG mill-ball mill combination delivers the desired throughput at the correct size for efficient separation when processing ore of the design hardness, some adjustment must be made to maintain this condition when the ore changes. The processing of ore softer than design will result in overgrinding, unless:• the throughput is increased inversely to the change in hardness which lowers recovery by overloading the separation facilities;• or the SAG mill feed rate remains constant, but the speed is reduced to feed coarser material to the ball mill for finish grinding to the desired size.There is also the effect of changing milldiameter to consider. A nominal 36 ft diameter SAG mill will have an effective diameter of 35 ft with new liners and 35 ft 6 in. with worn liners. A mill designed to operate at 0.76 p.u. (per unit) of critical speed with new liners (9.84 rpm) will be changed to 0.765 p.u. with worn liners. If 0.76 p.u. is the desired value, the mill speed should be reduced to 9.77 rpm."

Jan 1, 2003

In 1962, minerals beneficiation showed definite signs of coming out of the doldrums into which it has drifted after the uranium boom. Demand by steelmakers for high-grade iron pellets has created the need for concentrating plants to upgrade specular hematite by spiral concentration or flotation and magnetites by magnetic means and flotation. According to a paper given at the AMC annual meeting by C. S. Arms of Pickands Mather, "the shipment of pellets, started in the mid-1950's, has increased to 17.6 million tons in 1961 from North American operations. Many plants already underway will raise this production to about 42 million tons by 1965. This will be a very sizeable percentage of the total iron ore production contemplated by that date." Iron ore concentration methods are gradually raising the assay of pellets into the 65 to 69% Fe range and lowering silica to the 4 to 7% range. Quebec Cartier's Lac Jeannine concentrator went into operation in late 1961 and all grinding units were running by 1962. The Iron Ore Co. of Canada's new Carol Lake plant was started in mid-1962.

Jan 2, 1963

By Peter Dowden, Trevor Carter, Allan Moss, Bruce Downing, Richard Beddoes

Traditionally (with a few exceptions) tunnel boring machines (TBMs) have been utilized on tunnel projects where the risks associated with deep tunnels (rock burst, squeeze, etc) are low (or expected to be low). This has generally been due to the extremely adverse consequences of entrapping or damaging a TBM under such conditions; but also due to the relative difficulty of dealing with these ground conditions in the confined working area of a TBM, in comparison to a drill and blast heading. This paper review the constraints of operating a TBM in a deep tunnel and discusses related project experience, particularly recent and current experience with TBMs in the deep Alpine Base Tunnels. Potential future applications of TBMs in the development of large, deep underground mines are also discussed.

Jan 1, 2007

By Saeed Salehi Malekshah

In hybrid foundation system or piled raft foundation (PRF), the raft has adequate bearing capacity and piles are usually required to ensure overall stability of foundation and also to act as settlement reducer for high rise structures. When piles are connected to the raft, a high axial stress may develop and one alternative is to disconnect the piles from raft and consider them as stiffeners for supporting soil. This system is known as disconnected piled raft foundation (DCPRF). Cushion, a compacted coarse grained soil layer, can be used beneath the raft to redistribute and adjust the stress ratio of piles to subsoil and plays an important role in mobilizing the bearing capacity of subsoil and modifying the load transfer mechanism of piles. In this study, finite element method (FEM) has been employed to investigate the effect of different parameters such as cushion stiffness, gap height, raft thickness and piling configuration on the behavior of disconnected piled raft foundation. The analysis is performed on different foundations of hypothetical and real case histories. Results indicate that increasing the raft thickness reduces the differential settlement and pile head axial stress. Concentrating the longer disconnected piles similar to connected ones beneath the central area of raft, decreases settlement of raft. With increasing cushion stiffness, vertical stress ratio of piles to subsoil increases, but settlement decreases. Increasing gap height from 0.1 m to 1 m decreases the vertical stress ratio of piles to subsoil.

Jan 1, 2011