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By R. L. Veenstra

This paper explores the connection between the stresses observed and the failure mechanisms present in the modelled cemented paste backfill. In order to look at this connection, the authors have used a previously developed model to conduct a sensitivity analysis of the model?s strength and permeability input parameters. The results from the sensitivity analysis were then compared to determine what causes modelled stresses and failure mechanisms to vary. Increased insight into the behaviour of the modelled paste will help clarify how paste behaves in the field.

Aug 1, 2013

By S. Markstrom

The Boliden AITIK copper mine is located 100 kilometres north of the Arctic Circle in northern Sweden. A pre-feasibility study was conducted in 2005 with the aim of increasing the capacity of the existing processing plant. After analysis, options to upgrade the existing plant were abandoned in favour of building a new processing plant, with higher capacity and therefore greater profitability. A new plant could be designed with greater flexibility to make potential future expansions easier. A feasibility study for a new 36 Mt/y processing plant including fully AG grinding circuits and flotation was completed in 2006. The project was approved by the Boliden board shortly thereafter. Construction started in the beginning of 2007 and was completed during 2009. Commissioning of the new plant was undertaken in the first half of 2010. The grinding circuit consists of two lines with each line consisting of a 22.5 MW AG mill and a 10 MW Pebble mill in closed circuit with a spiral classifier. The nominal production level is 2 200 t/h for each grinding line. This paper presents the start-up and operation of the grinding circuit.

Jan 1, 2012

By H. J. B. Couto, J. G. S. Puelles, M. L. Torem, R. H. Rojas, A. G. Merma

Understanding the limits of fine particle flotation is fundamental to achieving a significant and selective separation. Conventional flotation processes are not suitable to treat these particles because of their low collision efficiency. This problem can be overcome by decreasing the bubble size or by increasing the apparent particle size. However it is worth noting that the use of small bubbles or micro bubbles also involves some disadvantages such as their low momentum resulting in a slower process comparing with conventional flotation. Electroflotation is an attractive alternative for treating fine particles with small bubbles less than 100 µm, generated by the electrolysis of water. In this sense, this study assesses the effect of current density and pH on bubble size in a binary electroflotation cell. An increase in the bubble generation rate was reported with an increase in current density. In addition, at acid pH values, the size of oxygen bubbles increased and conversely decreased at basic pH values; this may be due to the electrostatic attraction between the oxygen bubbles and the anode resulting in a greater nucleation time. An opposite trend was observed with the hydrogen bubbles. These results are in agreement with their electrokinetic studies, which reported that at acid conditions the bubble surface may be positively charged for both the hydrogen and the oxygen bubbles. Finally the bubble size was slightly affected by the electrolyte concentration, resulting in smaller diameter bubbles at higher concentrations.

Jan 1, 2016

By H. J. Glass, J. G. L. Bekkers

"In order to determine the feasibility of a hydraulic ore hoisting installation, the optimal operating conditions were calculated for applying such a system at the Detour Lake Mine of Placer Dome Ltd. Next, a financial analysis was conducted in order to estimate the cost per tonne for hydraulic hoisting of the ore. Subsequently, the cost per tonne was compared with the hoisting costs associated with a new borehole hoist. Installing a hydraulic ore hoist at Detour Lake Mine was found to be feasible with considerably lower costs per tonne of ore. The applied research method appears to be very functional and can be used to do similar research for other mining operations. IntroductionThe principle of hydraulic ore hoisting is well known, yet hardly accepted in hard rock mining. Application of the system would result in a smaller diameter shaft requirement and a flexible, easily expandable system. However, underground ore size reduction might be necessary and practical experience with the system is limited. Following recent innovations in the field of pumping hardware, e.g. new GeHo and Siemag Transplan equipment, hydraulic ore hoisting should be seriously considered for certain mining operations. As a case study, a design was made for the development of the newly found QK-Zone at Placer Dome Ltd.’s Detour Lake Mine. Hydraulic ore hoisting has been compared with conventional skip hoisting by establishing the optimal operating conditions and pumping equipment requirements for similar capacities at a selected mining operation. Generally accepted equations for slurry transport were used to predict the variation of pressure and power requirements as a function of hourly production and pipeline diameter. These data are used to select suitable equipment and estimate cost figures in order to make a financial assessment."

Jan 1, 1998

By Neil Campbell

"The Pine Point area is on the south shore of Great Slave Lake, 510 air miles north of Edmonton and J JO miles south of Yellowknife, N.W.T. The occurrence there of lead and zinc was reported in J 899 by R. Bell (5) of the Geological Survey of Canada, and in the following years several claims were staked and some prospecting was done. In 1928 Atlas Exploration Co. took over the property containing the discovery occurrences. In 1929 The Consolidated Mining and Smelting Company of Canada Ltd. (""Cominco"") and Ventures Ltd. participated with Atlas in forming the Northern Lead-Zinc Co., which, under the direction of J. M. Bell, carried out 24,499 feet of drilling in the discovery and surrounding areas. Two shafts and many surface pits were also sunk. This work showed that the discovery deposits contain about 500,000 tons of lead-zinc ore, but no new orebody was found.In 1936 D. F. Kidd (11) drew attention to the highly significant space relations between the base-metal discoveries at Pine Point and the projections of certain major Precambrian faults mapped earlier by C. H. Stockwell. Geological work by Cominco in 1940 and subsequent years suggested the presence of mineable deposits within a belt of land including part of the area of earlier field work and extending far beyond it. Between 1946 and 1954 exploration financed by Cominco and Ventures Ltd. included 182,950 feet of diamond drilling, 383 feet of sinking, and 240 feet of drifting, raising, and crosscutting. This work was successful in finding substantial quantities of new ore in places where bedrock is completely concealed.The topography is one of low relief, characterized in many places by swampy muskeg and shallow, marl-bottomed ponds. The area where ore has been found is generally higher ground which, though not well drained, is comparatively dry. It is also marked by raised beaches and a few sand dunes overgrown by small spruce and pine. Bedrock is generally overlain by a variable thickness of hard, glacial boulder clay. This in turn is covered by silt, sand, and gravel, probably deposited from the waters of Great Slave Lake, which formerly extended many miles beyond its present southern shore."

Jan 1, 1949

By A. F. Matheson

"Bankfield Consolidated Mines, Limited, and Tombill Gold Mines, Limited, in the Little Long Lac area, Ontario, mined an orebody that was common to both. The discovery' of this orebody was made by surface prospecting in May, 1932, on Bankfield ground, following an original discovery made in the same manner on the same property on a small reef in Magnet lake in October, 1931. The production from the two mines between 1937 and 1942 was approximately 135,000 oz. gold from about 420,000 tons of ore, an average grade of 0.32 oz. a ton. Production was nearly equally divided between the two properties. Both mines are now closed, the ore exhausted.""The ore is mainly sheared and fractured greywacke and porphyry impregnated by silica and small amounts of metallic minerals. To a lesser extent there are definite quartz veins in the ore zone""(l). The metallic minerals present were principally pyrite, arsenopyrite, pyrrhotite, and native gold .As at other mines in the Little Long Lac area, an elongated, broad, deep trough of folded, steeply dipping volcanic and sedimentary rocks, striking roughly east-west and surrounded by younger granite, is host to the orebodies of the Bankfield and Tombill. In the immediate area of the two mines iron formation and conglomerate bands occur nearby both north and south of an intrusion of porphyry-Cliorite, suggesting repetition of beds and folding. Although considerable drag folding is in evidence, folding on the above scale has neither been proved nor disproved."

Jan 1, 1954

By Carl Sonnen

Reading the newspapers, you will know that opposition to ratification on economic grounds always points to the view that action will result in major price increases for energy (to both industry and households) with consequent severe losses of energy production and a loss of competitiveness for energy-intensive producers (i.e., in your kinds of industries). You might think of this as the ?carbon tax? fear, and you should note that many of the initial policy development experiments included variations of this theme. Analysis reported in late 2000 and into early 2002 reported reductions in energy production in the long run of between 10% and 20%. At the upper end of that view, these were the kinds of numbers reported in the Industry Canada study ?leaked? to the Press last week. The consequences of this approach included significantly uneven negative effects for some provinces (e.g., Alberta, but also Saskatchewan and Newfoundland). It had been agreed by the First Ministers of Canada, however, that the policy should not yield those results so development in recent months has focused on eliminating sector and therefore provincial ?sore thumbs?. Although an emissions trading system, which represents this type of approach and directly impacts costs of production, continues to be featured in the new or current policy and is applied to the Minerals Industries among others, it is designed to be implemented in such fashion that the costs are more moderate than before. And because the industries covered by permits are almost all price takers, there is no device for moving an increased price signal forward to ?consumers?. What this does do is even out negative effects among sectors in the economy and for provinces, but at the expense of government financial results.

Nov 1, 2002

By Li Chongyang, Liu Baolan, Jia Xiaolin, Li Suping

An Al/Al2O3 gradient coating applied on a heat-resistant stainless steel was prepared through a slurry process by using aluminum and ?-Al2O3 powders as the transition filler material, alpha alumina as the surface coating material, aluminum dihydrogen phosphate as the binder, and sodium molybdate as the corrosion inhibitor. The effects of heat treatment temperature, adhesive/filler ratio and ?-Al2O3 content on the bonding strength, microhardness and thermal shock resistance were investigated. The crystal phase and microstructure were characterized by XRD and SEM. The results indicated that the composition of the coating changed continuously from surface to coating-substrate interface. The coating could offer high bonding strength and good thermal shock resistance when heat treated at 700°C.

Jan 1, 2010

By G. R. Guillet

Important resources of kaolin, refractory clay and lignite, not found elsewhere in Ontario, occur with quartz sand of glassgrade quality in unconsolidated Mesozoic sediments of the Moose River Basin in northeastern Ontario. These materials comprise the Mattagami Formation of Lower Cretaceous age, which overlie in some places a thin Jurassic unit and a thick Paleozoic section, and underlie as much as JOO m or more of glacial and marine sediments and a uniform capping of muskeg. The Mallagami Formation is known from deep boreholes to exceed 100 m in thickness and to consist of two phases: an earlier Type A unit of dark-coloured carbonaceous clays and lignite, and a later light-coloured (Type B) unit of kaolin-bearing quartz sands and bright-coloured refractory clays. Remoteness, poor access, and difficult physical environment have inhibited the exploration and development of these resources.

Jan 1, 1984

By S. Caron, M. Bourassa, J. Châteauneuf, L. Tardif

"Since many years, the Yvan-Vézina gold plant custom mills and processes different ore types that show different behaviors. Because of this, cyanidation control is more complex than for a typical milling operation. In 1992, a Cyancor™ on-line « free cyanide » analyzer has been installed for monitoring and optimizing cyanidation. This implementation significantly reduced cyanide consumption for the overall cyanidation process. In order to further reduce cyanide costs, an automatic control strategy has been implemented to decrease fluctuations of« free cyanide » from their set points.This paper outlines the major steps of the project: process control audit, control strategy development, implementation and running-in period. Control strategy features include data filtering modules, adaptive PID algorithm and set points management modules are also presented. Finally, the strategy efficiency is illustrated with load-disturbance responses.IntroductionLocated in northwestern Quebec, the Yvan-Vézina plant has an average capacity of 1300 t/d using carbon-in-pulp technology. In 1991, the Yvan-Vézina gold plant was processing three types of ores (Beauchemin, Mouska and Silidor mines) and a pyrite concentrate (Beliveau mine). A cyanide reduction program was then undertaken to reduce « free cyanide» fluctuations <6>. To reach this objective, the optimum cyanide concentration was determined for each ore, a continuous monitoring method with the Cyancor™ on-line analyzer was developed and a tighter control of cyanide addition was applied. These modifications to the leaching practice significantly reduced cyanide consumption.After a while, it was observed that regulation of « free cyanide » concentrations could still be improved by the use of an automatic control strategy. Yvan-Vézina and CRM began collaborating in 1995 to develop and implement such a strategy. Results show that main disturbances of the circuit (e.g. ore mineralogy and pulp feed rate) can be significantly overcome in order to reduce their effects on the leaching operation."

Jan 1, 1998

By Delio J-J Tortosa, Fred F. Langford

"The Cenex orebody occurs at the intersection of northwest and northeast-trending fault zones that formed during post-Hudsonian uplift. The ore is localized in breccia zones, along faults, and in veins and adjacent wallrocks. The host rocks are Tazin quartzo-fe/dspathic mylonites and ultramylonites and chloritesericite- quartz-graphite-feldspar mylonite schist. The uraniumbearing minerals are finely disseminated pitchblende and uraniferous titanate.The earliest mineralization may have been associated with /ate-stage retrograde metamorphism in the mylonite schist. The main stages of mineralization were associated with brecciation, hematization, carbonatization, and chloritization of the mylonites and ultramylonites. Uranium mineralization was clearly much later than any igneous or metamorphic activity associated with the Hudsonian orogeny.Late post-orogenic uplift, erosion, and deposition of the Martin continental clastics in fault basins were coeval with uranium mineralization. The deposit is consistent with a meteoric-hydrologic system constituting a source for orebearing fluids, hence the close spatial relationship of the uranium deposits in the Beaverlodge area with the basal unconformity of the Martin Group."

Jan 1, 1986

By A. Jordens, Y. Zhiyong

"IMBSRE, one of the largest rare earth element (REE) producers in China, produces a rare earth oxide (REO) concentrate as a by-product by floating the middlings stream from a low intensity magnetic separation step in the main iron ore processing stage. As the mine depth has increased, flowsheet changes in the main iron ore circuit have reduced the REO grade and increased the magnetite to REO ratio in the middling product used as flotation feed for the REO circuit. Extensive laboratory work was carried out and identified a new modified hydroxamic acid product, Florrea 8920, that could provide better metallurgical results over the standard hydroxamic acid used as the main collector. This paper briefly reviews the use of hydroxamates in the flotation of oxide minerals, provides detailed information on the different hydroxamates available from Florrea and then provides a case study of the successful implementation of the Florrea 8920 product in a commercial Chinese REE flotation plant. The case study consists of a one year program of pilot plant testing and industrial trials to confirm the results of laboratory tests. The implementation of the new collector resulted in an improvement in grade and recovery to 61% and 64% respectively. The new collector also provided significant economic and environmental benefits.INTRODUCTIONThe flotation of rare earth element (REE) bearing minerals is a topic which has been dominated in the English language literature by the work conducted on the Mountain Pass bastnäsite deposit (Pradip, 1981; Fuerstenau, Pradip, Khan, & Raghavan, 1982; Pradip & Fuerstenau, 1983, 1985, 2013; Fuerstenau & Pradip, 1991; Fuerstenau, Pradip, & Herrera-Urbina, 1992; Herrera-Urbina, Pradip, & Fuerstenau, 2013). By far the most important collector type used for the flotation of rare earth minerals (REM) is hydroxamates. These reagents were initially extensively described as REM collectors in the English literature by Pradip (1981) however they have been successfully applied to numerous other minerals such as: cassiterite (Sreenivas & Padmanabhan, 2002); pyrochlore (Gibson, Kelebek, Aghamirian, & Yu, 2015); hematite, chrysocolla, rhodonite, hubnerite and pyrolusite (Fuerstenau, 2005); and malachite (Lenormand, Salman, & Yoon, 1979) amongst others."

Jan 1, 2016

By Simon Pelletier, Jose Delgadillo, Dave Page, Pramod Kumar, Raj Rajamani, Dilek Alkac, Martin Fillion

"In general, many past works examine mill load, mill power, shell lifter design etc with a view to improving the mill capacity. On the contrary, only a handful of papers have addressed the transport of fine slurry through the pulp lifters. We present the flow dynamics of pulp lifters via laboratory scale experiments, high speed photography and modeling with computational fluid dynamics. Next, the flow behaviour in ArcelorMittal’s Mont-Wright autogenous mill discharge flow is examined. In an effort to improve mill throughput, a comprehensive simulation and plant scale study of the mill was taken up with a focus on the shell and pulp lifter design. The shell lifter was found to be at its optimum limit for breakage of ore particles given the constraints of wear life and occupied volume. Next, the pulp lifter study was taken up with computational fluid flow code and discrete element code. The simulations directly showed that there was considerable carry-over of slurry. This effect was traced to the area restriction in the pulp lifter channels. Further, crash-stop studies confirmed slurry pooling within the mill. Thus it was readily apparent that mill throughput can be increased if the pulp-lifter could be redesigned. Consequently, the discharger section of the pulp-lifter was redesigned.First, this paper outlines the modeling in laboratory scale studies and plant scale studies leading up to the discharger design. Next, the discharge flow in seven different published mill surveys is predicted with computational fluid dynamics (CFD) methodology shown here. Finally, Mont-Wright mill circuit performance before and after the discharger redesign is described. The usefulness of fluid flow simulations in the design of pulp-lifters is emphasized."

Jan 1, 2012

By Xiaolin Cheng, A. J. Sinclair

"Norm calculation procedures originally designed principally for igneous rocks are very rigid in their application and, in general, do not utilize important alteration minerals. For instance, volatile components are essential constituents of many metasomatic rocks but either are not used or are not used effectively in determining normative minerals by the CIPW norm or Niggli-Barth norm procedures. Our approach to determining norms for metasomatic rocks allots all major, minor and volatile constituents to a set of standard normative minerals which are commonly observed as products of hydrothermal alteration. A useful procedure is to have a metasomatic norm approximate the mode as closely as possible. Petrographic information helps to provide the necessary mineralogical constraints. With the recognition of an immobile component and knowledge of sampling and analytical errors in lithogeo chemical data, it is possible to recast norms into amounts of alteration minerals relative to a given amount (100 grams) of parent rock. Combining these results with the calculations of absolute loss or gain of individual chemical constituents and considering errors (e) for an appropriate confidence level, an overall (net) material exchange equation can be presented as follows:<equation>where all items have extensive units (e.g., grams). The model includes the initial and final mineralogy of rocks (evident in the field) as well as gains and losses of specific elements. Only those constituents whose calculated losses and gains are significantly different from zero are retained in the above model, and only the normative minerals with abundances significantly different from zero are included in the model (equation). One advantage of the chemico-mineralogic model is that parent rock and product are modeled in mineralogical terms that are familiar to and easily usable by exploration geologists."

Jan 1, 1995

By Xiaolin Cheng, A. J. Sinclair

"Abstract - Norm calculation procedures originally designed principally for igneous rocks are very rigid in their application and, in general, do not utilize important alteration minerals. For instance, volatile components are essential constituents of many metasomatic rocks but either are not used or are not used effectively in determining normative minerals by the CIPW norm or Niggli-Barth norm procedures. Our approach to determining norms for metasomatic rocks allots all major, minor and volatile constituents to a set of standard normative minerals which are commonly observed as products of hydrothermal alteration. A useful procedure is to have a metasomatic norm approximate the mode as closely as possible. Petrographic information helps to provide the necessary mineralogical constraints. With the recognition of an immobile component and knowledge of sampling and analytical errors in lithogeochemical data, it is possible to recast norms into amounts of alteration minerals relative to a given amount (100 grams) of parent rock. Combining these results with the calculations of absolute loss or gain of individual chemical constituents and considering errors (e) for an appropriate confidence level, an overall (net) material exchange equation can be presented as follows:SMineralparent rock ± e + SConstituentgained from solution ± e= SMineralaltered rock ± e + SConstituentlost from wall-rock ± ewhere all items have extensive units (e.g., grams). The model includes the initial and final mineralogy of rocks (evident in the field) as well as gains and losses of specific elements. Only those constituents whose calculated losses and gains are significantly different from zero are retained in the above model, and only the normative minerals with abundances significantly different from zero are included in the model (equation). One advantage of the chemicomineralogic model is that parent rock and product are modeled in mineralogical terms that are familiar to and easily usable by exploration geologists."

Jan 1, 1995

By J. Petit, P. Girard, A-M. Gilbert, D. Faucher

L&apos;annee 2000 a été une année stratégique et significative pour l&apos; Aluminerie de Bécancour dans la réduction des gaz a effets de serre. L&apos; équipe s&apos; etait donne comme defi un jour d&apos;arriver a l&apos;objectif de zero effet d&apos;anode dans les sa11es de cuve (720 cuves au total). Le cha11enge s&apos;averait tres ambitieux car la fa<;on d&apos;alimenter une cuve d&apos;electrolyse pour obtenir son maximum de rendement faraday est de travailler le plus pres possible de l&apos;effet d&apos;anode pour eviter l&apos;embourbement de ce11es-ci. Ceci signifie que techniquement nous a11ons en moyenne, quotidiennement, 12500 fois pres de l&apos;effet d&apos;anode sur !&apos;ensemble de nos 720 cuves qui produisent aujourd&apos;hui environ 405 000 tonnes d&apos;aluminium liquide annuellement. Des 695 kg equivalent en C02 par tonne d&apos;aluminium produite en moyenne annue11ement, de 1990 a 2000, nous en sommes rendus ace jour a environ 35 kg equivalent en C02 par tonne produite. Nous sommes pres d&apos; atteindre notre objectif mais les demiers gains sont plus difficiles a atteindre. Les strategies d&apos;automatisme et d&apos;informatique, incluant l&apos;aspect de !&apos;implication humaine sur les bonnes pratiques de travail sur les cuves d&apos;electrolyse, sont les cles de ces resultats.

Jan 1, 2006

By H. J. McQueen

Pyro-reduction of ores to metal products developed markedly through the industrial revolution into the great depression. Nineteenth century resource and environmental sustainability were haphazardly improved by many process changes, although the motivation was primarily reduction in labor, feed stocks and fuel. Some notable achievements were coke and hot air for blast furnaces (later from waste heat stoves), puddling of wrought iron and steel ingot production with convertors advancing into oxygen use and continuous slab, billet and strip casting. Although advances in one sector were often counteracted by fall-backs in others, there was progress in that the resource consumption and pollution per unit of production was decreased. Improvements in the 2 decades following WW2 were mixed but popular notice of environmental hazards forced governments to legislate pollution controls and initiate steps in resource conservation. The energy crisis of the 1970’s saw an industrial energy-saving campaign and legislation of technology assessment procedures. Up until mid 18th Century, the training of iron masters depended on apprenticeship with some formalized knowledge from medieval books such as those of Biringuccio (1540) and Agricola (1556). The advances were very slow partly due to absence of scientific concepts of the smelting process. Nevertheless, some iron masters succeeded in improving the process and described procedures to instruct others. With the surge of steam power and the reverberatory puddling process for ductile wrought iron (WI), machinery changed from wood (iron strap reinforced) to WI machinery. With the clarification of the reduction and oxidation mechanisms by Cavendish and Lavoisier (~1780), productivity in iron production surged. The mechanical testing and microscopy of Kirkaldy (1862) spurred understanding of processing and properties of WI and steel. The various forms of C in steels were determined by chemists at the end of the 19th Century. It also became possible to control metal and slag chemistry in the open hearth furnace. But understanding of the transformations during heat treatment of steel only came in the first decades of the 20th Century.

Jan 1, 2012

By L. Xia, B. Hart, K. Douglas

In the flotation of Rare Earth Element (REE) bearing minerals, oxalic acid is reportedly acting both as a depressant and pH modifier. Testing has established the significance of oxalic acid in the flotation process however its specific role in either the recovery or selectivity of REE over their gangue minerals is not well understood. Pulp pH reduction trials with alternative acids have not shown the same effect on the REE mineral recovery or the depression of gangue phases. This work examines the effect of oxalic acid on the surface of gangue minerals (quartz and carbonates (dolomite and calcite)) in a series of conditioning tests. Gangue surface analyses by TOF-SIMS indicate that oxalic acid inhibits the transfer of secondary ions generated during the conditioning process from one mineral phase to another. In this regard, the oxalate anion acts to fix ions in solution through chelation, limiting their participation in surface adsorption.

Jan 1, 2014

By L. H. Chen, Y. C. Chen, Leo Benyamin, W. C. Chen

"To investigate the evolution of fluid-driven fracture of rock-like material subjected to borehole fluid pressure and its consequential damage with regard to post-peak stabilization, micro-seismic activities have been monitored using nondestructive technique of acoustic emission (AE) corresponding to the macro-scale complete history of loading curve by setting the hollow cylindrical external circumferential strain to be a closed-loop feedback signal during servo-fluid-driven tests. Development of a novel fluidinduced loading system injected from internal borehole as well as monitoring system were equipped such that the initiation and propagation of micro-cracks enable to analyze experimentally. By programming/controlling either injection rate or fluid pressure, synthetic sandstones with low-permeability made by cement mortar were conducted in this study. It found that both the growth of macro-crack initialized intensively as reaching the breakdown pressure and the micro-seismic activities represented by AE locations show nice agreement. The experimental results in this paper provide better understandings of fluid-driven fracture mechanism.INTRODUCTIONFluid-driven fracture is a process of generating cracks by injecting viscous fluid into solid material. Conventionally, fluid-driven fracture tests have been performed by mining industry to measure the in situ stress (Haimson & Fairhurst, 1969) and fluid-driven fracture has been employed by the petroleum industry to recover oil and gas. Additionally, the mechanism of crack growth or the extension of existing cracks is important to the evolution of volcanic dikes over distances of a few kilometers (Lister & Kerr, 1991; Rubin, 1995), crack propagation in dams (Bolzon & Cocchetti, 2003) and the disposal of radioactive waste (Sun, 1969)."

Jan 1, 2015

By T S. Cochrane

A variety of practical tests have been tried in the mining industry to determine the support properties of mine roof bolts. Such tests include torsion wrench readings, hammer blow tests and the use of plates with built-in tension indicators. This paper gives some details of pull tests with a hydraulic jack, as carried out in coal mines of western Canada. M A~Y criteria exist for establishing the efficiency of roof bolting, and the one adopted de-pends on the nature of the problem and on the individual leanings of the investigators. Consequently, sufficient studies have not been made from a common viewpoint or under similar geological and techno-logical conditions to compare these methods of evaluation. However, regardless of whether certain tests provide sufficient factual data to form a basis for theoretical research on bolting or not, many of these tests can and do provide a positive means of judging the suitability of chosen roof bolting techniques and equipment under definite geological conditions.

Jan 1, 1963