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By M. A. Cristovici

"In the last few years CANMET has taken the initiative by investigating the possibility of reactivating abandoned old tailings dumps (for gold production) which would be of potential economic interest across Canada.Nova Scotia was one location where numerous gold processing plants were in operation in the early days. A survey of the old tailing dumps was conducted and some areas of interest were selected. Among them were the sites identified as Lake Charlotte and Forest Hill.Ore samples collected from those tailing ponds were examined for their chemico-mineralogical composition and investigated for gold extraction. Three technological concepts were tested: flotation, direct cyanidation and flotation followed by cyanidation of the flotation concentrate. The combined flotation- cyanidation variant, yielding a gold recovery in the range of 90%, was recommended for processing the tailing ore.Pilot-plant runs carried out by a commercial testing firm (data not included in this paper) confirmed the conditions and results of CANMET's technology.As a result a consulting-engineering firm designed the processing plant which is expected to begin operation in the near future.IntroductionIn the last few years CANMET initiated a research program to locate in Canada, abandoned gold-silver tailing dumps of potential economic interest and to explore the possibility of recovering the precious metals from these old deposits by modern techniques.A literature search revealed that the first production of gold in Canada was recorded in British Columbia in 1858 and that, production prior to 1900 was essentially restricted to the Yukon, British Columbia Nova Scotia and Quebec. During the early 1900s, Ontario, Manitoba and the North West Territories joined the ranks of the gold producers.Early milling and recovery methods were mainly restricted to sluice boxes, gravity stamps and amalgamation. Froth flotation and cyanidation were introduced at about the turn of the century.Recovery of gold at plants using flotation and cyanidation was very good, therefore the tailing ponds resulting from those operations would, very likely be of little or no economic importance. However, the gold recovery at the amalgamation and gravity concentration plants appeared to be lower, indicating the possibility that significant amounts of recoverable gold would have been carried with the tailings to the dump sites."

Jan 1, 1986

By M. J. Nicol

The leaching of gold with thiosulfate solutions in the absence of ammonia and copper ions was investigated using electrochemical and kinetic methods. In sodium thiosulfate solutions, the electrochemical oxidation of gold was hindered and the leaching rate using pure oxygen as the oxidant was very slow. It was found that the addition of a small amount of thiourea or formamidine disulfide to the thiosulfate solution greatly enhanced the oxidation of gold. However, the enhancement to the overall dissolution of gold using dissolved oxygen as the oxidant was limited. This was attributed to the fact that the oxygen reduction process was unaffected by the additives and remained slow, which limited further improvement to the overall kinetics. An alternative oxidant, the ferric EDTA complex having a reduction potential of approximately 0.12 V, was found to be promising. The cathodic reduction of ferric EDTA was fast and reversible at neutral pH. While the ferric EDTA complex was effective in oxidizing gold, it did not appear to significantly oxidize thiosulfate. A thiosulfate solution containing thiourea and ferric EDTA has been shown to quickly dissolve gold in the form of a powder as well as from gold ores. In the leaching with the ores high gold recoveries of above 90% was achieved with the best performance obtained in neutral solutions (pH 6-7).

Jan 1, 2005

By P. J. Dunlop

THE object of this paper is to present a brief survey of the work done and the results obtained in controlling dust at the Hollinger Consolidated Gold Mines milling plant. The plant includes all primary and secondary crushing, grinding, and treatment operations. The major items of equipment are: (1) Underground Crusher Plant 1 48 in. by 60 in. jaw crusher, crushing run-of-mine ore to minus-6-in. Rate: 420 tons per hour (2) Surface Crusher Plant 3 No. 772 gyratory crushers 3 4 ft. by 16 ft. trommel screens 4 No. S gyratory crushers Reducing ore to rninus-172-in. Rate: 420 tons per hour (3) Roll Plant 5 sets of 62 in. bJ: 24 in. rolls 7 5 ft. by 10 ft. v1bratrng screens Delivering a minus-3/16-in. finished product Rate: 420 tons per hour (4) Grinding Plant 4 7 ft. by 15 ft. low discharge grate ball-mills 4 12 ft. reciprocating rake classifiers Rate: 4,800 tons per 24 hours Maximum capacity: S,800 tons per 24 hours

Jan 1, 1939

By D. M. Watson

Mineral discoveries and subsequent extraction have led to the establishment of many small communities, some major towns and a few cities . In Canada, such developments have essentially occurred without benefit of long-range regional or local planning. In the past, this was not a cause for concern. Now, however, rising expectations and reorientation of social values have placed increasing responsibility on government and industry to ensure the long-term viability of communities and regions. Such responsibility means large investments by government in infrastructure and by industry in extractive and processing plants. Uncertainty in the interpretation of ore reserve estimates becomes a critical factor. The traditional methods of reporting reserves - "proven", "probable" , "possible" - may be useful in individual mine production planning, but they are inadequate for planning industrial and public infrastructure, The need for a better information base is critical, with clear and precise definitions of what is being reported, but we are a long way from achieving it. The challenge is therefore to develop a closer professional relationship between government and industry and to tie mineral development to long-range regional strategies.

Jan 1, 1977

By Jose Alberto Gonzalez, Said Sharif Mahboob, Jeffrey L. Shepherd

"During the industrial electrowinning of zinc, uneven growth can cause short-circuits and make the deposits more sensitive to the presence of impurities that can significantly impact current efficiency. To produce levelled zinc deposits, additives such as glue, licorice and sodium silicate are often added to the electrolyte. Even in the presence of additives, uneven zinc growth still takes place because of the combination of hydrodynamic and electrolysis conditions in the cell house. Recent advancements in imaging spectroscopy and scaling analysis have opened an avenue to further study the effects of additives on zinc growth morphology. In this study, Atomic Force Microscopy (AFM) and scaling analysis have been used to monitor zinc growth characteristics including roughness, periodicity, aspect ratios and growth mechanisms as a function of electrolyte composition as well as deposition time. Zinc was electrodeposited from an industrial electrolyte containing a host of additives onto an aluminum cathode with a platinum wire serving as the anode. AFM images of the samples were collected to obtain 3D topographical information on which scaling analysis was performed to extract details on root-mean-squared (rms) roughness, periodicity (grain size), aspect ratio of surface features and growth mechanism. This analysis provided information on the mechanism by which the previously mentioned variables can impact short term growth and also provided a prediction of expected growth at long deposition times.INTRODUCTIONElectrowinning is one of the final stages in the industrial production of zinc metal. It is during this process where dissolved zinc ions undergo electro-reduction from an acidic electrolyte onto an aluminum cathode and are later recovered by stripping the zinc metal from the substrate. However, due to the nature of zinc growth as well as the various operating conditions, zinc deposition may occur unevenly, sometimes causing short-circuits that can cause electrode damage and reduced zinc production."

Jan 1, 2016

By Richard E. J. Putman

THE MINERALS INDUSTRY has always been a heavy user of energy in most of its unit operations: power in the mining, comminution, flotation and electro-winning processes; fuel in its smelting and other metallurgical processes; and, of course, fuel in the on-site generation of power and steam. Many of the techniques for using computers to perform energy management and conservation tasks have been known for some time, but they have not been widely implemented because the return on investment has hitherto been insufficient. Recent trends, however, have not only caused the dollar return to rise due to higher purchased energy costs, but the cost of the investment to fall. One trend has been the generally lower cost of computer control systems themselves, due to vendors having adopted the newer, lower-cost and more reliable electronic component technologies now becoming universally available. The second trend is the development of low-cost, but high-speed, remote multiplexing devices, which have reduced considerably the expense of bringing data from points scattered over a wide area, which is typically the case when applying energy management systems to a minerals processing plant. By taking advantage of these and related developments, computer control systems can now have a rewarding impact on plant energy management and conservation practices, and recent advances in application technology have opened up new and additional opportunities for energy cost reduction and control.

Jan 1, 1978

By C. Grisanti, E. Prina Howald

The major of Swiss territory is occupied by mountains. Natural events as floods, debris flows, landslides, rockfalls, and avalanches regularly threaten the safety of people and properties. On the one hand, extreme weather events cause great damages, on the other hand, the enhancement of territory’s exploitation increases the risk. The Swiss Government makes many efforts to deal with the prevention of natural hazards, especially through measures of land management. As stated by federal law, Swiss cantons are obliged to establish hazard maps and to take the risk into account in the land management. Hazard maps are based on the hazard matrix, whose abscissa and ordinate are probability and intensity of the event on site. This project focuses on rockfalls. It consists of three main parts: the creation of a database to collect data on site, the creation of a catalog with all type of measures, and the development of a methodology for the analysis of the effectiveness of protective measures. The creation of the database allows us to collect information: about the site, about protective structures implemented on it, and about failures. With many multiple choice fields and few free text fields, it can collect data in a homogeneous way, without redundancy. The catalog has to be a tool that gives a basis to make decisions. It collects information about all types of protective measures implemented on Canton Vaud’s territory or available on the Swiss market. Free text fields allow for data storage of specifics, to give a complete view of structure’s characteristics and potentials. Methodology consists of four steps. The core of the procedure is the structure’s evaluation following a score system; it allows for calculation of reduction factors that have to be applied to intensity and probability parameters of the structure. Then it is necessary to convert the reduced structure’s intensity value into a residual site’s intensity value. Although the first step enables us to choose suitable measure for a specific site, it is not necessary to perform it. Second step allows us to evaluate structures under scenario 0, where structures are in best conditions. Third step allows us to evaluate structures under six scenarios of possible failings. Fourth step allows us to convert structure’s reduced intensity into event’s residual intensity and to establish the new point on hazard matrix. While the procedure has already been defined, details of score system and conversion have to be developed during the second phase of the project.

Jan 1, 2015

By H. A. Pearse

Introduction This paper may be regarded as another instalment of the story of the Britannia milling operation. From time to time in the past, articles (1) have been prepared by various members of the staff, giving details of crushing, grinding, and flotation treatment for the normal Britannia ore. It is not, therefore, the purpose of the present paper further to discuss what may be termed the standard milling operation, but rather to describe a flotation practice which has been evolved directly as a result of the general depression. The normal Britannia ore mixture contains chalcopyrite and pyrite as the main sulphide minerals, together with minor gold and silver values. The standard milling practice, evolved during several years of experimentation, provided for bulk flotation of the two sulphides after primary grinding to only approximately 35-mesh, followed by regrinding of the bulk concentrate, with subsequent separation of the chalcopyrite and pyrite to make a marketable concentrate of each mineral. However, in the face of a constantly increasing surplus of copper on the world markets and a steadily falling price during 1930 and 1931, it was obviously undesirable to continue producing large quantities of this metal at a loss. On the other hand, Company officials were very reluctant to add to unemployment by closing down entirely, provided operations could be continued without excessive losses. Fortunately, the existence was known of a fair sized body of ore, quite low in copper and relatively high in zinc content, with also a very considerably higher gold value than that prevailing in other sections of the mine.

Jan 1, 1934

By Allan R. Punkkinen

Safe extraction of the valued ore resource in the deep levels of VALE Creighton Mine has progressed in a pillar-less fashion using vertical retreat, slot-slash and uppers retreat methods since the cessation of ?cut and fill? mining in the late 1980?s. Sequencing of the panel extraction and filling has been the key to successful exploitation of high stress orebodies at depth. In late 2010, discussions between the Operating Department and Creighton Ground Control revealed an opportunity to evaluate a trial primarysecondary sequence in the west end of the 400 Orebody at the 2340m horizon. To manage the trial primarysecondary project, a high level risk analysis and management of change was carried out to mitigate potential danger. As part of the requirements, an instrumentation project was conducted in the hanging wall and footwall bottomsills of the secondary panel and within the secondary panel itself. The extraction sequence was modeled with Map3D® software, confirming high stress levels with the advance of the primary panel. Enhanced ground support was installed based on modelling results. A key objective of the instrumentation project was to verify support system response to mining and to obtain knowledge in regards to the behavior of the stope. This paper describes the first time that this type of new innovative instrumented rockbolt technology had been used in a hard rock mining environment. Understanding of the physical deformation mechanisms of ground support in response to high stress conditions is the basis for an effective ground control strategy. The data played an important role in subsequent enhanced ground support system design at the mine and importantly, established the fact that the secondary pillar had not totally failed. Subsequent cavity monitor results helped establish that fact.

Jun 1, 2012

By P. E. Fox, R. S. Cameron

"The QR gold deposit lies in the Cariboo plateau region of central British Columbia. The deposit was discovered in 1977 and since then a mineable reserve of 1.3 million tonnes grading 4.7 g/t Au has' been outlined in three separate zones. Soil sampling of glacial tills followed by diamond drilling of favourable host rocks proved to be key exploration techniques.The deposit is situated in the southern Quesnel terrane along the eastern fringe of the Intermontane Belt which here comprises a sequence of basic and intermediate volcanics and a series of stocks of alkaline affinity; generally diorite, monzonite and syenite. Hornfels and epidote-rich ferromagnesian exoskarn and sulphide-rich mantos have developed in a metamorphic aureole formed around a central diorite stock. Gold-rich zones lie along the outer periphery of the aureole where bodies of gold-bearing epidote-rich skarn and auriferous mantos rich in epidote and pyrite have formed in beds of calcareous tuffite lying at the top of a thick basaltic sequence. The deposit is regarded as' a subclass of gold skarn deposits. Diagnostic features are its association with alkalic intrusive rocks in a subvolcanic setting and the presence of oxidized, epidote-rich mineral assemblages.IntroductionThe QR gold deposit lies within the Cariboo plateau region of central British Columbia, 58 km southeast of Quesnel. The deposit, owned by Kinross Gold, was discovered during a regional reconnaissance program by Dome Exploration (Canada) Limited and Newconex Canadian Exploration in 1977. Considerable exploration and development has been done since that time. Mineable reserves of 1.3 million tonnes grading 4.7 g/t Au have been outlined to date in three zones."

Jan 1, 1995

By L. Tapia

The main disturbance for stability in primary grinding using SAG mills is related to continuous changes in the ore being fed to the plant, such as size and hardness. Searching for stability is the first step to accomplish, before trying to maximize the mill throughput. The time variability in the characteristics of the ore being fed from the mine to the plant must be known or inferred to perform adaptive changes in the grinding process control. In day to day operation, such information is not available in real time. Transport times and inventories between the mine and the plant complicate the situation. Under this scenario, Minera Los Pelambres implemented a grinding optimization strategy, based on the real time analysis of certain process variables, such as ore size, mill current consumption, pebble generation and throughput. As a result, both grindability and stability indexes are inferred. This is equivalent to inferring the ore characteristics by knowing its effect on the grinding behavior. These two indexes permit control of the SAG mill total charge level and hence, allow optimization of throughput by means of an expert control system.

Jan 1, 2007

By D. N. Thurston

Luscar Stereo commenced construction of the mine at Coal Valley, Alberta, in August, 1976. It is designed to produce approximately 2.5 million clean short tons of steam coal annually - 2.0 million tons per year being committed to Ontario Hydro and 0.5 million tons per year being committed to Neptune Terminals for sale on the export market. The project involves constructing a heavy-media coal preparation plant, erecting a 42-cubic-yard dragline, constructing a shop/office complex, and developing three surface mining zones and associated facilities. As there were no existing facilities in the Coal Valley area, it was necessary to establish access roads, an airstrip, temporary utilities, fuel supplies, a construction camp, rail upgrading and communication services.

Jan 1, 1978

By J. D. Zhu

A numerical model for predicting microporosity formation in aluminum castings has been developed, which describes the redistribution of hydrogen between solid and liquid phases, the transport of hydrogen in liquid by diffusion and Darcy flow in the mushy zone, One of the key features of the model is that it uses a two-stage approach for porosity prediction, In the first stage, the volume fraction of porosity is calculated based on the reduced pressure, whereas, in the second stage, at fractions solid greater than the liquid encapsulation point, the fraction porosity is calculated based on the volume of liquid trapped within the continuous solid network, which is estimated using a correlation based on the Niyama parameter, The porosity model uses thermal data calculated using the commercial finite element package ABAQUSTM. The model has been applied to examine the evolution of porosity in a series of experimental samples cast using unmodified A356 in which the initial hydrogen content was varied from 0,048 to 0.137 [cc/100g], A comparison between the model predictions and the experimental measurements indicates good agreement in terms of the variation in porosity with distance from the chill and the variation resulting from initial hydrogen content.

Jan 1, 2005

By Yan Qun, Chen Xiao-ming, Ma Pei-long, Luo Xian-ping, Luo Cai-gui, Feng Bo

The effect of leach promoting reagent LPF on the leaching process of a weathered crust elution-deposited rare earth ore has been investigated and the mechanism is discussed. The result shows that the leach promoting reagent LPF can enhance the leaching extraction of rare earth ore effectively. With the addition of LPF to the lixiviant at a concentration of 0.1%, the leaching extraction increased by more than 8%, the ammonium sulfate concentration could be decreased by 25%, and the leaching liquid/solid ratio reduced by 34%. The mechanism analysis shows that LPF can react with rare earth ions and form soluble coordination compounds, thus reducing the activity of the leached rare earth ions, increasing the concentration difference for ion diffusion, and promoting the rare earth leaching process. These results will hopefully help point to a new approach to making the leaching process of low-grade weathered crust elution-deposited rare earth ore more efficient and with lower lixiviant consumption.

Jan 1, 2014

By Geo. D. Furse

"The information that has accumulated regarding the geology of the McIntyre mine is the result of work by several geologists and, as might be anticipated, their conclusions have varied. The writer has been at the mine only a few years and due to wartime conditions has not been able to study and review the mine's geology as thoroughly as his predecessors. Where the writer's conclusions differ from those of previous authors, it should be noted that he has been unable to re-map all the workings in which flow contacts are exposed, but has endeavoured to describe the structure as indicated by the evidence he has been able to observe. He wishes to thank H. G. Skavlem and H. S. Robinson for their constructive criticism of this paper, and McIntyre Porcupine Mines, Limited, for permission to present it. A list of references is appended.The McIntyre mine is in the central part of the Pearl Lake section of the Porcupine gold area. It includes the ""bed of Pearl lake, twenty-two claims to the north of the lake, and the Platt Vet lot to the southeast. It is bordered on the west by the Hollinger and on the east by the Coniaurum property. The chief ore-bearing veins on the upper levels lie very close to the north shore of the lake, but some occur under the lake, and others of lesser importance are found to the southeast. The most important veins are Nos. 3, 5, 7, 10, and 25. Some of the veins extend into the Hollinger. on the west and others cross the east boundary into the Coniaurum. The total production since the commencement of milling in 1912 to the end of March 1947 has been $168,448,218 in gold and silver from the milling of 17,690,963 tons of ore."

Jan 1, 1954

By Mohamed Hamoud

Relative permeability curves represent an important element of special core analyses, but challenges remain in obtaining valid results and the extrapolation and use of existing permeability results is problematic. This situation is compounded in cases where core properties are altered from changes in effective stress. During the production of oil and gas reservoirs, the effective stress changes as a result of changes in pore pressure or temperature. Therefore, changes in rock properties such as porosity and permeability will occur and will consequently influence reservoir performance calculations. An experimental program was carried out to understand the behavior of dense, reconstituted sand samples at low effective stress states. Drained triaxial compression tests were set up to study the effect of stress alteration on relative permeability data through porous media. Initially, a saturation stage was performed followed by isotropic loading to bring the core sample to reservoir fluid and stress conditions. Then, while axial (deviatoric stress) loading was applied to the sample, a series of absolute and relative permeability tests was performed under steady state flow at different levels of strain during pre and post peak shearing stress. The stress-strain behavior results from the study revealed that the absolute permeability decreased during isotropic loading (compaction) and increased during shearing (dilation). However, the shape of relative permeability curve changed from contraction to dilation and showed higher initial kro and the lower initial kro respectively. The goal of this project was to understand the behavior of both absolute and relative permeability at different stresses. It is expected that geomechanical processes will be adopted for special core analyses to support the current integration of geomechanics into reservoir engineering. This will be required if, during SAGD, conventional and/or unconventional reservoir simulation, reservoir engineers implement a proper set of relative permeability data at each in situ state of stress, instead of constant curves throughout the field?s life.

Jun 1, 2012

In this paper, the use of electrochemical AC impedance spectroscopy (EIS) for in-situ diagnosis of high temperature PEM fuel cells is described. EIS was performed on single cell hardware, built in-house, using a fuel cell test station modified to operate up to 120°C and 30 psig. Electrode kinetics, membrane resistance, porous-layer and mass transport impedance of MEAs, assembled in-house, were measured at various current densities for the purpose of validating the test station and cell hardware, and for optimizing MEA and flow-field designs. The effect of temperature and humidity on the various impedances was investigated. Impedances obtained at lower and higher temperatures were compared to obtain insight into the issue of water management in operating fuel cells.

Jan 1, 2005

By M. Aljarrah

The phase equilibria in the Mg-Al-Ca system was investigated experimentally by differential scanning calorimetry (DSC) and X-ray diffraction (XRD) techniques similarly the Mg-Al-Sr system has been studied using DSC and XRD as well as scanning electron microscopy/energy dispersive spectrometer (SEM/EDS) and quantitative electron probe micro-analysis (EPMA). A new ternary solid solution MgxAl4,xSr was confirmed in Mg-Al-Sr system, which is a substitutional solid solution of Mg atoms in Al4Sr. Maximum solubilities of 21.3 at.% Al in Mg17Sr2 and 11.4 at.% Al in Mg were observed. It was also noticed that Mg38Sr9 dissolved 12.5 at.% Al. In the Mg-Al-Ca ternary system, one of the invariant transformations predicted by thermodynamic modeling was verified experimentally and found to occur at 512°C with composition close to 10.8 at.% Ca, 79.5 at.% Mg and 9.7 at.% Al. A ternary solid solution (Mg,Al)2Ca was confirmed where large solid solubility of Al in Mg2Ca was observed.

Jan 1, 2006

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 K. Soucek, J. Ptácek, A. Hastíková, R. Kukutsch, P. Konícek, P. Waclawik

"Cable bolts are used frequently as a secondary support system (with steel arch support) in difficult stress-strain conditions of deep coal mines. The load transfer mechanism of cable bolts depends on several factors, such as the strength, deformation and geometric properties of the bolts, resin and the surrounding rock mass so-called cable-resin-rock system (CRR system). The bonding length and bolt/borehole diameter ratio strongly influence the final bearing capacity of the CRR system.The study presents the behaviour of CRR system during a pull-out test which is usually used in the carboniferous rock mass in the Czech part of the Upper Silesian Coal Basin. A series of 28 pull out tests were performed on 3-m-long cable bolts, with various combinations of borehole diameters and bonding lengths, to understand this behaviour. Boreholes were drilled into a solid rock mass consisting of fine-grained sandstone to guarantee similar conditions during the pull-out tests. Video inspection and measurement of borehole diameters were performed to determine their quality and real diameters. Three characteristics were observed from pull-out test results: ultimate pull-out load; displacement of the end of bolt and system stiffness. Numerical modelling by FEM (Finite Element Method) was used to determine the stiffness of the CRR system for variable bolt/borehole ratios and bonding lengths each under constant load. A linear elasto-plastic model and a mohr-coulomb model were used for cable and resin-rock respectively. The results of the experiment may contribute significantly to improving of the methodology of cable bolts installation as well as the design of used cable bolts."

Jan 1, 2015