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By R. M. de Carvalho

Empirical and phenomenological models of SAG and AG mills have dominated the scene for the last few decades, being used nearly every time a mill is scale-up or an attempt is made to improve its performance. However, in spite of their success, these models fail to describe the details of both the grinding environment and the breakage mechanisms. The result is a generally good track record, with a few – but very important – instances when these models fall short in their predictions, which can be very costly. Further, nearly all of these models require detailed calibration to industrial and pilot plant data, being costly in their application, although still with limited predictive capabilities. Recognizing these challenges, a new model framework has been proposed which overcomes the limitations of currently used models by coupling the microscale population balance model, the discrete element model and functions that describe internal classification at the mill grate. This model framework has already been applied to describe breakage in ball mills, with showing very promising results. However, in the case of SAG and AG mills a much greater level of complexity is involved in the model, given the interaction between the mechanical environment that is formed totally or, in part, by the ore itself, and the breakage response in the mill. The paper describes the model framework, demonstrating how it can address appropriately effects such as mill speed, mill filling and size distribution, on the response from the mill. Some of the advantages of the model are related to its intrinsic multi-component and dynamic nature, which allows simulating appropriately mixtures of ores of different competences in a transient manner.

Jan 1, 2012

By C. G. Kemsley

THE ore as hoisted is very wet, and difficulty was experienced i~ screening it to remove the fines before going to the secondary crusher. In fact, the fines had a tendency to form balls and roll down the screen, and only a small percentage was removed. Their inclusion with the other ore going to the Symons secondary crusher caused excessive spring action and pounding between the adjustment ring and main frame, resulting in abnormal wear between the two. To overcome this, it was decided to wash the fines through the primary screen, and use an Akins classifier to de-water the screenings, pumping the overflow from the classifier up to the mill and discharging the oversize onto the mill-feed belt.

Jan 1, 1945

By P. Condori, G. Rech, J. Winnett

"Palabora Mining Copper has a unique ore body composition which unlike other copper ore bodies has three main components in significant proportions; these are copper bearing ore, magnetite and dolerite. The high content of dolerite, a hard barren material, creates a high proportion of pebbles which normally are recycled back to the mill. This action increases the mill bearing pressure and power progressively until corrective actions are taken.A logical action to solve the pebbles generation would be to incorporate a pebble crusher. This in fact was done however two fundamental issues were encountered; the high content of magnetite and existence of a cyclone classification section. Due to the high content of magnetite, metal detectors have not been able to work efficiently to separate tramp metal which causes damage to the pebble crushers. The existence of cyclones in the circuit had a detrimental effect on the final product when the pebbles crusher was online producing coarse sandy material.Due to the difficulties in treating pebbles via conventional procedures and the unique Palabora ore composition and characteristics, sorting technology was investigated at laboratory and pilot scale. It was found that a combination of optical and electromagnetic sorting could efficiently separate dolerite from the copper bearing and magnetite ores.This paper reports the findings of the laboratory and pilot scale work performed and discusses the additional benefits to the circuit."

Jan 1, 2012

By I. Mc Dougall, H. Joubert, G. de Villiers

The use of sidewall copper cooling systems to prolong furnace campaign life is becoming an accepted technology solution in the base metals industry. Tenova Pyromet has designed and installed a number of sidewall copper cooling systems in base metals furnaces, including the platinum industry. Apart from increasing the furnace campaign life through the formation of a stable freeze lining, a well-designed copper cooling system enables the plant operator to focus more on optimizing the process to achieve throughput and recovery targets, and to accommodate more varied and available concentrate feed blends. The paper discusses the design of sidewall copper cooling systems for copper smelting and converting furnaces to achieve the above objectives. More specifically, the design of copper cooling systems for top submerged lance furnaces are discussed. An overall increase in furnace heat losses has been raised as a concern for intensively cooled sidewalls. The paper explores the overall heat loss expectations for copper cooled furnaces versus traditional refractory lined furnaces. In addition, the potential use of alternative cooling media is discussed. INTRODUCTION Base metal smelting and converting furnace technologies have been evolving continuously over the past century to satisfy the need for higher throughput, improved efficiency, and longer campaign life. To accommodate these demands, in particular higher smelting intensity and throughput, furnace bath containment systems had to improve. The use of pure refractory lining systems has slowly made room for the use of more intensively cooled lining systems (Joubert, Nikolic, Bakker & Mc Dougall, 2016). These cooling systems evolved from external shell cooling, such as shower or film cooling, to copper plate coolers extending into the furnace refractory lining, and high intensity stave or panel coolers (Verscheure, Kyllo, Filzwieser, Blanpain & Wollants, 2006). Consequently, an increasing number of base metal smelting and converting furnaces are equipped with copper cooling systems, including flash furnaces (Bryk, Ryselin, Honkasalo, & Malmstrom, 1958; Yasuda, Motomura & Kawasaki, 2014; Marx, Shapiro & Henning, 2010), top submerged lance primary smelting and fuming furnaces (Bhappu, Larson & Tunis, 1994; Kim, Lee & Lee, 2000; MacRae & Steinborn, 2018), top submerged lance converting furnaces (Viviers & Hines, 2005; Nikolic, Hogg & Voigt, 2018), primary platinum smelting electric furnaces (Nelson, Stober, Ndlovu, De Villiers & Wanblad, 2005; Jones, 2005; Hundermark, De Villiers & Ndlovu, 2006; Mc Dougall, 2013), and electric slag cleaning furnaces (Joubert, Nourse, Masters & Hundermark, 2005).

Jan 1, 2019

By Gerardo Fuentes

Arsenic extraction from Chilean copper concentrates up to nearly 99% was achieved, using hydrothermal reactions. Arsenic appears in nature in more than 200 mineral species, being arsenopyrite (FeAsS), enargite (Cu3AsS4), and tennantite (Cu12As4S13) the most common species. In addition, arsenic is present in a large amount of copper concentrates, produced in northern Chile. Medical statistics show that in northern Chile, the amount of cancer to the lung, skin and bladder are the highest in the country. The latter situation, demonstrates the importance of studying metallurgical processes that do not generate atmospheric pollution. The hydrometallurgical processes such as hydrothermal treatment in autoclave reactors, do not produce gaseous emissions. On the other hand, the arsenic remains in solution from where it can be transformed in scorodite by widely known methods. Previous works about hydrothermal treatment of enargite have shown the feasibility of transforming the enargite of the copper concentrates into chalcocite or mineral species of the chalcocite family such as djurleite, digenite and for this reason enrich the concentrate in copper and pass the arsenic to solution. For this research, two Chilean copper concentrates were used, concentrate 1 with 5.5% arsenic and concentrate 3 with 1.8% arsenic. These concentrates were subjected to a complete chemical and mineralogical characterization. Later these concentrates were carry out to batch tests of hydrothermal treatment. Also, these concentrates were subjected to grinding to have different particle sizes. For the hydrothermal tests, a liter capacity Autoclave Engineer reactor was used. Characteristic of this reactor was the maximum temperature 350°C, 5000 PSI pressure, and 900 rpm agitation speed. Kinetic tests were carried out with the two concentrates maintaining the same solid: liquid relationship, the same agitation velocity and the variables studied were treatment temperature, time of reaction, concentration of copper in the solution and grain size of the concentrates. The conclusions of the study indicated arsenic extraction of the order of 93.98% from the concentrate 1 and arsenic extraction of the order of 98.74% from concentrate 3. After the hydrothermal treatment, the solids and solutions were characterized chemically, by electron microscopy and X ray diffraction. Also the solids were characterized by grainsize through a particle size analyzer (MICROTRAC). Results of batch treatment shows that arsenic can be release almost completely from real copper concentrates using this hydrothermal process and the next stage will be a scale up process in order obtain results for pilot plant design. INTRODUCTION Arsenic is an impurity that appears associated with copper minerals forming enargite, tennantite, tetrahedrite, and that due to the pyrometallurgical treatment either in conversion or roasting furnaces, it goes into the atmosphere together with the sulfur dioxide. A great quantity of literature can be found to eliminate arsenic or try to separate arsenic from copper. The methods used are mainly leaching processes with or without pressure (Padilla, Jerez & Ruiz, 2015) with different reagents like chloride media (Herreros, Fuentes, Quiroz & Viñals, 2003) or chloride media with sulphuric acid (Riveros & Dutrizac, 2008) or sodium hypochlorite (Mihajlovic, Strbac, Zivkovic, Kovacevic & Stehernik, 2007). It is known too that Chile is the first copper producer in the world and a great quantity of its minerals are in the north of the country, in Antofagasta.

Jan 1, 2019

By G. Vibert Douglas

It has long been recognized that there are considerable difficulties connected with the physical and chemical explanation of shoots of ore. The literature of Mining Geology has frequent references to this subject; but the reasons given for the actual location of primary ore-shoots have been very tentative. In practice, the geologist or miner depends to a great extent on sampling and assaying to determine the boundaries of profitable ore within the mineralized zone. An ore-shoot is a portion of a mineralized zone which has a sufficient concentration of valuable minerals to make it ore. Ore deposits have been classified according to many schemes. There are classifications based on morphology and on genesis. However, it is also possible to classify hypo-gene hydrothermal ore-bodies in terms of ore-shoots or vice versa. A.-Ore-deposits in which the whole of the mineralized zone is ore, which is the same as saying that the ore-shoot extends throughout the mineralized zone. An example of this type of deposit would be the pyritic mineralization of Rio Tinto. B.-The second type would comprise those deposits in which the ore-shoots bear some relation to the geological structure of the area: all deposits in which 'bonanzas' occur in folds in the zone, at the intersection of veins along certain fault (or joint) features and other such controls. There are a great many examples of this type: (a) The Rhodesian copper lodes, where Bancroft and Gray have pointed out the association of the shoots of ore with drag folds. (b) A similar association has been pointed out by Faribault for some of the gold veins of Nova Scotia, e.g., Mount Uniacke. (c) The great bonanza of the Comstock lode in Nevada. C.-Deposits in which the localization of ore has been effected by the chemical character of the wall-rock. Examples of this type are the Fahlbands of Scandinavia, and the 'indicator' deposits of Ballarat, Australia. D.-Lastly, deposits in which there is apparently no structural and no chemical control.

Jan 1, 1934

By G. E. Agar, R. Stratton-Crawley

"The applicability of a hydrocyclone model to simulation of the cyclone banks in a multi-stage sandplant circuit producing mine back fill has been demonstrated. The model ha~; been used in conjunction with a modular computer program for circuit simulation in order to study the effect of changes in the operating conditions. It has been shown that weight recovery to sand fill increases as feed percent solids decreases, and, to a lesser extent as pressure drop across the banks increases. An increase in apex diameter also causes an increase in weight recovery. Increased weight recovery must, however, be balanced against sump an1l cyclone capacity and dilution of sand fill by fines. The predicted results from circuit simulation were in good agreement with plant data.The model has been found to be applicable to widely different ores."

Jan 1, 1979

By C. Greimel

Modern roadheaders provide a safe and cost-effective, yet very flexible way of mechanical tunnel and roadway excavation. In the last years, SANDVIK Mining and Construction has developed a NEW ROADHEADER GENERATION, which incorporates new features, allowing significant improvements of underground excavation. Partial face cutting machines such as roadheaders excavate the desired profile by means of a cutter unit mounted on a swiveling boom. This flexible method for mechanical excavation makes the roadheader suitable for a large range of profile varieties and most rock characteristics. Over 1,250 roadheaders have been delivered since the 1960s from the Zeltweg plant of Sandvik Mining and Construction, with the current products ranging from the light-duty, 130kW MR220 machine, widely used in the tunneling and coal industry to the heaviest 300kW tunneling and hardrock mining roadheaders. Roadheaders are generally used in coal mine development, salt/potash mining as well as construction and hard rock mining. This paper describes the technology behind the succesful introduction of hard rock cutting with roadheaders, and aims to offer best practise operation experiences from various hard rock cutting sites.

Oct 1, 2010

By D. Laguitton, D. Cimon

"BILMAT is one of the most powerful algorithms in existence for material balance computation in mineral processing flowsheets. It is based on a hierarchical decomposition coupled with the Lagrange multipliers method widely reported in the literature. Flowrates can be calculated optionally for pulp, solid or water. Assays are adjusted for a variety of subnetworks, such as assays of the solid as well as assays of fractions of the solid called level 4 data (l: pulp, 2:solid and water, 3:assays of solid, 4:assays of classes of solid).BILMAT4 is a new implementation of BIU1AT that operates in a new microcomputer environment and makes the method more accessible than ever. Its main features are a full-screen colour editor allowing graphic flowsheet drawing and data entry with automatic error checking. Mass balance equations are automatically generated by analysis of the graphics and corresponding data, thus relieving users from the error-prone definition of networks. Sensitivity analysis is performed to assess confidence intervals of computed flowrates and adjusted assays.BILMAT4 incorporates an option for gold leaching circuits where the element to be balanced appears in both the solid and liquid phases with negligible effect on the mass flows of solids. Recoveries are computed in all streams. This program is currently released by CANMET as part of the CAMP collection for Computer Aided Mineral Processing. A complete sample run of the program is discussed."

Jan 1, 1989

By T. G. Joseph

The chicken and egg scenario where adverse truck motions cause ground deterioration and poor ground profiles that in turn cause adverse truck motions is a downward deterioration spiral that dominates in our industry. If we can remove one action, the reaction must stop and vice-versa. A simple 'truck to excavator' load data analysis and wireless communication system is outlined in this paper; that will provide visual assistance to the excavator operator in achieving improved load placement and balance in a truck body. In turn this will reduce the subsequent hauler duty cycle adverse motions and g levels that contribute to structural fatigue, higher tkph, reduced tire life and ongoing maintenance of haul roads

Nov 1, 2011

By L. K. Mireku

"Abstract - The Halfmile Lake South Deep zone, Bathurst Mining Camp, New Brunswick, was discovered by Noranda Inc. (Exploration) as a result of a 3-D seismic survey in 1998 and the subsequent drilling of ten diamond-drill cores. The deposit consists of massive, breccia, and stockwork Pb-Zn-Cu sulfide minerals, and is hosted by a volcano-sedimentary sequence belonging to the overturned Ordovician Tetagouche Group. Epiclastic rocks and interbedded fine-grained felsic pyroclastic rocks dominate the stratigraphic footwall. Locally, crystal-rich felsic tuffs and subordinate epiclastic rocks comprise the immediate stratigraphic hanging wall. The entire stratigraphic sequence was intruded by quartz-feldspar porphyritic intrusions, and cut by intermediate and basic dikes. The volcanic and sedimentary rocks can be discriminated geochemically using trace element ratios such as Zr/TiO2 and Nb/TiO2, despite intensive alteration and cleavage development. These ratios indicate that four protolith volcanic compositions exist: rhyolite, dacite, andesite, and basalt. The aphyric and feldspar- and quartz-phyric volcanic rocks are dacitic and rhyolitic in composition; epiclastic rocks have trace element ratios consistent with dacitic compositions. Pearce element ratio diagrams, general element ratio diagrams, and petrographic observations demonstrate that the rhyolitic volcanic rocks exhibit evidence of albite, potassium feldspar, and quartz fractionation, dacitic volcanic rocks exhibit little evidence of any fractionation, and epiclastic sedimentary rocks exhibit evidence of quartz sorting only. Hydrothermal alteration is best represented by the presence of phengitic muscovite and daphnitic chlorite. Minor calcite occurs in the stratigraphic hanging wall, deep in the stratigraphic footwall, and in post-mineralization dikes, and thus is not interpreted to be part of the causative hydrothermal event. Element additions and losses during alteration have been used to determine net alteration reactions, and these have been used to identify alteration parameters that are independent of other forms of alteration and fractionation/sorting, and which can be used to guide exploration. These parameters include: a bulk hydrolysis measure, (2Ca+Na+K-2CO2)/Al; a muscovite alteration measure, K/Al; an albite destruction measure, Na/Al; a chlorite alteration measure, (Fe+Mg-S/2)/Al; a chlorite composition measure, (Fe-S/2)/Mg; a sulfidization measure, S/Ti; and a carbonatization measure, CO2/Ti. With the exception of the carbonatization measure, these alteration parameters define a distinct lateral and vertical zone of intense hydrothermal alteration in the stratigraphic footwall of the deposit, and demonstrate that the epiclastic rocks are predominantly chlorite altered, and the volcanic rocks are predominantly muscovite altered. Within the alteration halo, element additions of Fe and H, and element losses of Na are characteristic. Potassium was added to muscovite-altered rocks, but subsequently removed from chlorite-altered rocks. The results from this study demonstrate that metamorphism and deformation have not significantly obscured hydrothermal alteration signatures."

Jan 1, 2006

By G. E. Agar, W. B. Kipkie

"This paper deals with the prediction of locked cycle flotation results from data developed from individual batch tests. A postulate is made that the distribution of material in a separation stage is determined by the chemical conditions and the flotation time and that this distribution can be characterized by split factors which are constants for a fixed set of conditions. With this premise, it is demonstrated that a steady state balance can be calculated for a circuit.Although the necessary equations can be solved algebraically, a computer program was written that uses an iterative tec1nique to arrive at the steady state balance. The program is written so that a variety of circuits can readily be simulated.A number of examples are examined to demonstrate the validity of this simulation procedure. The sensitivity of the material balance to changes in the split factors was examined. Data developed from different flowsheets is presented on sulfide ores, on copper-nickel separation and on silver flotation,"

Jan 1, 1978

By P. B. Marchant

"Based on laboratory and pilot scale continuous biooxidation of complex sulphide concentrates, commercial processing design and scaleup considerations are discussed. Capital and operating cost estimates for commercial biohydrometallurgical operations are summarized and potential applications of biotechnology are discussed. Biooxidation as an oxidative pretreatment alternative to enhance precious metals extraction from refractory sulphide concentrates in stirred tank reactors has received considerable attention recently due mainly to advances in the practical applicability of the process. Biooxidation of sulphides is certainly not a new process, however, application and control in large scale hydrometallurgical operations to treat refractory sulphides remains conceptual and the limited data available is restricted to relatively small laboratory and pilot scale operations. It is the intent of this paper to indicate scaleup and plant scale process design considerations for commercial bioleach circuits, based on recent operating experiences with laboratory and pilot scale continuous bioleach systems. An indication of the expected range of applications will be presented parameters for optimization will be discussed."

Jan 1, 1986

By R. Lanthier, A. Broussaud, J. C. Guillaneau, D. Hodouin

This study presents a method for upgrading the information extracted from the measurements given by the sensors of a pilot grinding circuit. For that purpose raw signals are combined to process models for extracting, through filters, the best information on the process state. Two different filters are used; one is based on steady-state mass balance constraints and the other one uses dynamic mass balance equations allowing for material accumulation in the equipment. The filters are designed and tuned with the help of a grinding circuit dynamic simulator and are then implemented in the pilot plant. Their performances and usefulness are discussed.

Jan 1, 1989

By Liguang Wang

The froth phase in flotation has received much less attention than the pulp phase despite the fact that froth stability plays an important role in determining flotation performance. Froth stability is largely determined by the stability of thin foam films, which in turn has a strong correlation with the critical rupture thickness (Hcr) of the films. In the present work, a new approach to predicting the Hcr values of thin foam films in flotation froth phase was proposed and examined. The Hcr values were calculated using an advanced capillary wave model with input parameters being surface tension, film radius, capillary suction pressure, and intersurface force. The intersurface force was estimated by using the Stefan-Reynolds lubrication approximation to fit the measured thinning rates of single foam films formed in a Scheludko ring cell, where the film radii were less than 50 microns and were kept constant during the film-thinning process. A comparison between the predicted and experimental Hcr values was made for the films with the use of sodium chloride as background electrolyte and in the presence of various frothing reagents such as methyl isobutyl carbinol (MIBC), polypropylene glycol with an average molecular weight of 400 (PPG400), and sodium dodecyl sulphate (SDS), at different concentrations and film radii. It was found that the model correctly predicted the trends of Hcr-versus-concentration and Hcr-versus-film radius curves. Moreover, the predicted Hcr values matched well with the experimental ones of the foam films containing either SDS or PPG400. For the foam films containing MIBC, however, the model overpredicted the Hcr values. The reason for this discrepancy was discussed.

Jan 1, 2016

By B. Hoare, H. M. Hill

"SYNOPSISTailings volumes, disposal systems, effects of dam failures, construction materials, and concentrator process water volumes are discussed. Earth dams and tailings dams are discussed in detail. Some of the fundamentals of soil mechanics relating to earth dams are presented. Brief notes on optimization are presented. The development of a triplex meter for earth dam instrumentation is described. The advantages of the hydro-cycloned dam over the spigotted dam are outlined. INTRODUCTIONThe realistic and responsible recognition of the pollution problem, combined with the grossly increased volumes of waste material from large modern mining operations, has emphasized the demand for safe tailings dams at minimum cost.Tailings may be defined as the waste material from a mining operation after the process of concentration in which the minerals have been extracted for commercial use. The present revenue from the Canadian Mining Industry is slightly over $4,000,000,000 per year and it is estimated that the quantity of tailings produced exceeds 300,000,000 tons annually. In many instances, the volume of tailings from a mining operation is greater than the volume of crude ore mined on account of the small quantity of valuable mineral recovered during concentration, and on account of the ""swell factor"" resulting from the processes of drilling and blasting, crushing, and grinding of the crude ore. Some of the larger mine tailings deposits contain over 200,000,000 cubic yards and the associated tailings dams are among the largest man-ma.de structures in the world."

Jan 1, 1970

By John Crusius

? 3-year research program overview ? initial results- MainZone pit Waterline pit ? questions raised ? increasingly common in western N. America ? frequently low-pH waters with elevated concentrations of many metals ? water quality controls poorly understood ? some in U.S. are Superfund sites

May 1, 2002

By S. M. Bulatovic, D. M. Wyslouzil, K. R. Rawlings

"The suitability of a new organic reagent DS20 as a depressant for oxidized and carbonaceous pyritic lead-zinc ore from Nanisivik Mines Ltd. has been evaluated in the laboratory and in the plant.The depressant DS20 is a mixture of Lignosulphonate-Dextrin-Quebracho and was developed specifically for depression of highly oxidized and carbonaceous pyrite.The laboratory test work indicated that the poor metallurgy resulting from the oxidized ore could be improved to normal plant performance by the addition of the DS20 depressant with the existing plant reagents. The laboratory data suggested that lime consumption could be reduced when using DS20.In this paper, the development work and the plant trials with DS20 are described.INTRODUCTIONNanisivik Mines Ltd. treats approximately 2000 tonnes per day of lead-zinc massive sulphide ore, containing currently 1% Pb and 9% Zn. The concentrator operations have been described previously (1,2) and typical metallurgical performance is detailed in Table I.The concentrator flowsheet (Figure No. 1) and the standard reagent scheme (Table No. 2) demonstrate the relative simplicity of treatment of this coarse grained ore.A recently discovered satellite orebody - Area 14 - containing 2% Pb and 12% Zn was brought into production in October 1983. This ore had been oxidized to varying degrees by ground water; the pyrite mineralization was found to be very fast floating and a carbonaceous constituent present in higher than normal proportion also affected flotation. The simple high lime addition could not control the pyrite, and very low grade lead concentrates resulted; zinc metallurgy was also affected by this oxidized condition (Table 3)."

Jan 1, 1986

By C. R. Edwards

"Equity Silver Mines Limited owns and operates an open pit silver 111ine located 37 km southeast of Houston in the Omineca District of British Columbia, Figure l. The property is approximately 300 km west of Prince George and 417 km east of the Port of Prince Rupert. This is the largest silver mine in Canada and one of the five largest silver producers in the western world.Equity is a subsidiary of Placer Development Limited, which owns 70 of Equity's issued and outstanding Common Shares. Placer was responsible for financing and developing the property and now provides general management and administrative services.All mining is by open pit methods, using three 1600 P&H shovels, eight 45 t Caterpillar and three 77 t Wabco trucks, three 40R rotary drills, two D8 dozers, one 9888 front-end loader and other ancillary equipment. We are now phasing out the Southern Tail pit and bringing the Main Zone into productior; see Figure 2.Comminution in the concentrator is achieved via primary, secondary, and tertiary crushers followed by rod and ball mills. The flotation circuit, with Southern Tail ore, produces a concentrate containing between 3 000 and 6 500 g of silver per tonne, 201 copper, and 25 g of gold per tonne. Running Main Zone ore, concentrate grades will decrease to about 4 500 g of silver per tonne, 17% copper, and 18 g of gold per tonne. Design milling capacity is 5 300 tpd, which is often exceeded.The flotation concentrate contains relatively high levels of antimony and arsenic. Because of these impurities Equity was unable to obtain economically acceptable long-term sales contracts for flotation concentrate. For this reason a leaching process was developed, and a plant designed, built and placed in operation. Due to the complex and unique technology involved, many start-up problems were encountered but by March 1983 the leach plant was considered ""fully operational."" This paper describes some of our progress and problems in bringing the Equity leach plant through its start-up period."

Jan 1, 1984

By P. Mottahed, J. Ran

Mining practice and research have shown that the jointed roof in stratified rock behaves like a voussoir beam structure with strength greater than that determined by the continuous beam theory. Previous studies have demonstrated the voussoir beam mechanism and developed methods to estimate the crushing and buckling strength of voussoir beams. However, research on voussoir beams with multiple mid joints has not been suffICient and problems such as the voussoir beam support and applications of the voussoir beam mechanism to the mining environment have not been addressed. In this paper, mechanism of voussoir beams containing multiple mid joints and truss support are studied and applications of the voussoir beam mechanism to underground mine openings are discussed based on the numerical and experimental results.

Jan 1, 1995