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By R. F. Favreau, Patrice Favreau, Dennis Mahan

Cast blasting is becoming more and more popular, not only in coal mines but also in other operations which require excavation of an upper layer of waste rock to uncover temporarily and excavate a layer of ore, which may for example be material for the fertilizer industry.

Jan 1, 2014

By D. P. Nicholson

The current phase of office development at Canary Wharf in the London Docklands includes twelve multi-storey buildings varying from eighteen to forty stories in height. The area of Canary Wharf South comprises five multi-storey buildings with low level in fill podium and garden areas. Three of these multi-storey buildings have "pile-cap" designs where the entire building load is applied to the piles. The remaining two buildings have "piled-raft" designs where allowance is made in the design for part of the building load to be transferred to the raft formation. Using a piled-raft design approach has enabled savings to be made on the number of piles used below the raft. This paper describes the calibration analysis undertaken to validate the design method. The ground conditions at the Canary Wharf site are typically fill and recent gravel deposits over the overconsolidated clay and sand of the Lambeth Group. Below these strata is the Thanet Sand. The Lambeth Group provided the founding layer for the raft and contributed to the pile shaft resistance. The Thanet Sand stratum provided the bearing layer for the 1.5m diameter base grouted bored piles. The piled-raft design required an assessment of the building load transfer through the raft to the formation layer. This load transfer led to significant increases in effective stress in the soil below the raft and thence a corresponding increased the capacity of the piles. This interaction of the raft with the prepared formation contributed to between 27% and 45% increase in total vertical load carrying capacity of the piled-raft substructure compared with the pile-cap design method. The development of the piled-raft design was carried out in three main phases: ? Development of the approach and validation analyses. ? Design work on various schemes resulting in detailed design packages. ? Validation analyses using full 3D finite element analysis (presented herein). The validation of the piled-raft design approach was initially carried out against published case histories for piled-raft interaction. To improve on the validation work a full 3D finite element analysis of a simplified pile raft and superstructure (which contributes stiffness to the raft) was undertaken; the analysis included only a quarter of the structure due to assumed symmetry of the structure and vertical loading. This 3D validation analysis is presented herein. The analysis was carried out using the Oasys LS-DYNA finite element program. Prior to carrying out the analysis of the piled-raft an initial finite element analysis was carried out to back analyse a fully instrumented field pile test providing accurate modelling of a single pile performance. This back analysis allowed confidence in the soil parameters used in the 3D model; comparisons of shaft and base resistances between the pile test and the FE model calculations for the single pile are presented. The parameters provided in this work were then carried into the full 3D model of the piled-raft. The 3D model of the piled-raft structure included 18 piles (12 full piles and 6 half piles on an axis of symmetry of the model).

Jan 1, 2002

By P. Lozada

The objective currently demanded from controlled blasting techniques is to minimize damage to the remaining rock mass while protecting the integrity of mine walls and ensuring the quality of the fragmented material for easier extraction. Finding this balance represents one of the three main challenges faced by large open-pit mines. They must achieve mine stability by complying with slope designs while also maintaining good results in terms of fragmentation and equipment productivity. The main constraints are related to unfavorable geological conditions, water presence, limited drilling diameters and available explosive products, as well as managing drilling times and blast scheduling, among others. For slope control, in addition to presplitting, blasting designs generally include buffered rows, drilled with smaller diameters, and loaded with fewer kilograms of explosives than production holes. The objective is to reduce the powder factor (kg/t) to minimize the energetic influence on the walls and attenuate damage. However, this often requires using very short charge lengths compared to the bench height (one-third or less) and reducing the pattern geometry, which increases the number of holes per ton and drilling costs. This traditional technique of reducing powder factor in the buffered rows has the main limitation of not being able to distribute the explosive energy throughout the entire column, leading to fragmentation issues mainly in the steaming area. Measurements conducted by Orica in their operations indicate at least a 30% increase in P80 particle size in the buffer zone associated with this condition. To improve energy distribution, techniques such as decking, or vertically decoupled charges can be employed. However, these techniques cannot be applied under wet conditions, and strict control over implementation quality is required to avoid deviations, which increases loading operational times and resource required. In this sense, the use of less energetic and lower-density explosives is a better alternative. On one hand, they allow for complete charge columns in the buffered rows, ensuring homogeneous fragmentation, and on the other hand, they reduce the energetic influence on the slopes, significantly decreasing vibration levels. With less energy per kilogram of explosive (MJ/kg) and less charge per linear meter (kg/m), it becomes possible to handle higher specific charges and longer explosive columns, providing flexibility in drilling and loading design options without compromising slope stability.

Jan 1, 2024

By L. F. Bishop

THE ore bodies of the Butte district1 are found in many different vein systems having many different structural characteristics; some are narrow with self-supporting ore but with weak walls; some are wide with weak or strong ore and weak walls; some of the veins dip steeply and others do not; some have well defined walls, and others, in the "horsetail" area, are mined to sample limits. Consequently, many types of stoping methods are used in mining these ores. The stoping methods used in the Anaconda Copper Mining Company's properties are the square-set and cut-and-fill. The square-set method is the principal stoping method used because, generally speaking, the ore and walls are weak, the ore is high grade, and good extraction is required. These square-set stopes may be classified as conventional, vertical slice, slot, timber rill, and Mitchell slice types. The conventional type square-sets are those of various shapes and sizes, mined by horizontal slicing to the boundaries of the stopes. The rock is slid to the chute and the filling is moved by gravity. The ore and waste may be handled with a scraper when local conditions require it. The vertical-slice square-set system is the type used in narrow veins that are mined in vertical panels. The slot stopes are stopes in wide veins that employ a slot across the vein instead of a con- ventional chute to handle the ore. The timber rill fs a type of square set in which the ore is mined as in inclined cut and fill but the square-set timber is used. The Mitchell slice is the type used for some broken or heavy ore blocks, or for pillar extraction between two converging slot stopes. The cut-and-fill method is used where the ore will stand without much support although the walls may be weak. The principal type of this method is the horizontal cut-and-fill, with mechanical scraping. The inclined cut-and-fill, or rill, stopes are used in some veins too narrow for scraping. The production from the various meth: ods in use for the second six months of 1944 are shown in Table I. [ ] This paper deals mainly with the vertical slice and slot types of square-set stoping, because of their effect on production locally and their potential possibilities here and in other districts, with sufficient reference to conventional square-setting for comparison.

Jan 1, 1945

By Paul Gauthier

Aujourd?hui, avec un faible prix de l?or sur le marché, les opérateurs miniers doivent revoir leur façon de faire. La méthode de minage «Eureka» permet de réduire les coûts de production et d?accélérer la mise en production des chantiers. Les principales étapes du cycle de minage et les problématiques associées à l?utilisation de cette méthode à la Mine Bousquet y sont décrites.

Oct 1, 2001

Jan 1, 1883

By P. G. Killeen

Proper calibration of portable gammaray spectrometers and spectrometric logging equipment is essential if they are to be used for accurate quantitative determinations of radioelement concentrations. In the case of both types of equipment, it is necessary to determine the system calibration constants (stripping factors and sensitivities). In the case of borehole logging equipment, it is further necessary to determine the system response characteristics if the data are to be computer processed to improve the accuracy and resolution of the logs. Facilities are now available near Ottawa for the complete calibration of portable gamma-ray spectrometers and spectrometric logging equipment, in addition to already existing facilities for calibrating airborne gamma-ray spectrometers. Limited additional facilities are also available or planned in several other areas of Canada.

Jan 1, 1978

The 28th annual American Mining Hall of Fame Awards Banquet and fundraiser sponsored by the Mining Foundation of the Southwest will be held at the Marriott University Park Hotel, Tucson, AZ on Saturday, Dec. 4, 2010. The Mining Foundation of the Southwest is a nonprofit organization whose objectives are public education about the mineral industries, and recognition of outstanding accomplishments in and contributions to the fields of mineral and fuel resources. Funds are being raised to the support the foundation?s educational programs. Among these is the Educational Outreach Program operated jointly by the foundation and the Arizona Department of Mines and Mineral Resources.

Jan 1, 2010

By Nasser Madani, SULTAN ABULKHAIR

The abstract of the paper discusses the challenge of quantifying iron content in a coal deposit in Kazakhstan. The iron dataset is limited, coming from only three drill holes and some stope samples, while a large amount of geological information is available from legacy drill hole data. The paper proposes a workflow using multiple-point geostatistics to model geological domains and two-point geostatistics to model iron content within these domains. The results show that the direct sampling (DeeSse) algorithm effectively reproduces the complex seam layers, and sequential Gaussian simulation models the iron within each domain.

Mar 30, 2022

By A. J. S. Spearing, A. Mueller

The support of intersections in coal mines remains an important safety issue, mainly because the large diagonal span compromises the stability of the roof. This structural weakness is further exacerbated if the intersection is developed incorrectly, the pillar corners fail or the crosscuts are angled (not perpendicular). This report details the current support systems used and investigates unplanned falls of ground in intersections in coal mines throughout the United States. A possible failure mechanism is proposed and some suggestions are made to improve the effectiveness of the support in these vital areas.

Jan 1, 2009

By J Player, G Sweby, S Webber, E Jones

Seismic systems are a tool for the monitoring and forecasting the rock mass response to excavation. Common issues encountered at mine site audits and reviews are: how to design an effective seismic system, implementation of the design, interpretation of seismic source results and understanding the reliability of the seismic source. These issues are often a function of several items including: • Experience of site personnel in undertaking seismic system design. • Personnel not envisioning multiple phases of system expansion to understand system robustness issues. • System design/expansion occurring in response to damaging seismic activity rather than planned expansion of a system • The mine access development is often localised in comparison to the total orebody being mined hence, planning sensors in longholes in advance of development rather than in short holes close to development will improve the three-dimensional aspect of the network. • Limited site processing of the seismic event data, hence engineers do not see the uncertainty associated with event location, size, source and system layout. Mine site users require a framework to appreciate the challenges and limitations in locating large events. For example, event locations are given as precise measurements (to the nearest centimetre) whereas the volume of deformation resulting in the event often has dimensions of tens of metres or more (as defined by the source radius). A stronger awareness of the uncertainty of rock mass yield within large seismic sources will assist site users in the interpretation of rock mass damage. The encountered design and implementation errors are reviewed and discussed with a practical set of rules presented to provide a robust seismic system that provides consistent results and increases the user’s understanding of uncertainty in source location and size. The authors’ experience across multiple mine sites, seismic systems and damaging seismic events over a 30 year period has been summarised into practical rules for site personnel of all experience levels.

Nov 29, 2022

By J. C. Ingram

IT SEEMS particularly appropriate that, in celebrating its Diamond Anniversary, the Canadian Institute of Mining and Metalturgy chose our Province of British Columbia as its locale in this, our own Centennial year. I am sure your organization is justifiably proud of its achievements and growth over the period of its sixty years, and we, for our part, are justifiably proud of our growth over our first one hundred years. With your kind indulgence I pro-pose to talk to you today about our industrial growth, or, to put it an-other way, to highlight, historically, our progress in industrial development over the past one hundred years, and to take the liberty of speculating on what we may reasonably look forward to over the next few years. I am sure, Mr. Chairman, that some may have questioned the appropriateness of a talk on the industrial development of British Columbia to the Canadian Institute of Mining and Metallurgy. However, strangely enough, we in British Columbia owe our origin, constitution-ally and industrially, to the mining industry.

Jan 1, 1958

By Peter Cain

In response to the appearance of excessive convergence of bolted gateroads in the front abutment zone of retreating coal faces at Phalen Colliery, staff from the CANMET Cape Breton Coal Research Laboratory in Sydney, N.S. initiated a programme of roof profile measurements in the front abutment zone of longwall headgates. The results of these measurements allowed a characteristic deformation curve to be determined for each headgate, and the early identification of areas showing an unstable deformation trend. These areas were then reinforced with supplementary support. The monitoring programme was adopted and enlarged by the rock mechanics staff of the Cape Breton Development Corporation, and has been continuing for a period of approximately two years. A sufficient quantity of data now exists to be able to make an assessment of the effects of a number of mining parameters on the performance of the gateroad in the front abutment zone. The following paper describes the method of measurement, illustrated by typical results, and goes on to relate variations in rate and patterns of movement to geology, interaction, method of support and pre-mining stresses.

Jan 1, 1996

By W. Ghyoot, J. Boonstra, H. Dijkman, C. Buisman, M. Picavet

Paques and Umicore have demonstrated the feasibility of biological treatment of the highly complex Hoboken wastewaters in a1 m3/h pilot plant at Umicore Precious Metals, Hoboken, Belgium. In the first step arsenic was precipitated from copper smelter effluent as As2S3using biogenic produced H2S. Other metals such as copper, lead and cadmium were also removed as MeS to concentrations well below the discharge levels. Subsequently, sulfate and nitrate were removed to low concentrations (<300 mg/l and < 5 mg/l respectively) in high rate engineered bioreactors. Sulfide produced in the sulfate reduction process was recycled to step 1 for metals precipitation. Selenite/selenate was partly removed in the sulfide precipitation step, whereas the excess was biologically reduced and removed as selenium to concentrations <0.2 mg/l.

Jan 1, 2003

By E. R. Rodriguez

Improved practice resulting from recent changes in the method of supplying compressed air and in pneumatic drilling equipment used in secondary drilling and in development work at the Morenci mine of the Phelps Dodge Corp., has resulted in improved safety conditions, as well as in a reduced cost per foot of drilling. A large stationary compressor installed outside the mining area and the compressed-air pipelines in the mine were replaced by portable compressor units. A self-propelled, self-contained drilling unit was obtained for drilling large footages where short moves were involved. Large wagon-drill units were replaced by faster and lighter drill machines and conventional bits by carbide insert bits. The safe practices employed in air drilling and in the related blasting and scaling operations have contributed to an excellent safety record at this mine. The complete sets of instructions listed in the company codes of safe practice aid materially in training employees.

Jan 1, 1956

By Michael Taylor, Thomas W. BoBo

Currently two of the most important characteristics of construction aggregates are (a) the particle size distribution (psd) and (b) the “shape” of the aggregate particles. The long established test methods and standards for these properties require substantial resources and most suppliers can take samples and conduct tests at intervals measured in days (psd) or even months (shape). Furthermore these tests require time: so the results are available only after material has been stockpiled or shipped. In the rare cases where problems are found the out-of-spec material has often been shipped to points unknown. There are substantial advantages to be obtained if the psd and other geometrical properties could be obtained from the material as it moves through the production processes and if the results could be reported back within seconds or minutes to Plant Control Managers. This paper describes a single on-line system used to evaluate production of crushed material in a production quarry. The system consists of an enclosure (containing the camera and lighting etc.) mounted over a production belt. Images are fed by fiber optic cable to a nearby control room where the data are analyzed; stored; displayed; and made available for integration into a process control system. Numerous forms of display can be created according to the needs of the producer. Once programmed by an automation engineer all functions of operation are fully automated. The system has permitted over 400 tests per hour with a feed back time less than 2 seconds. Sufficient geometrical measurements are made so that many different “shape” factors can be computed on a similar time scale. The paper summarizes the results from approximately 100 shifts of about 8 hours each and compares the imaging method with the current standard hand methods. Study of the data generated showed that, when combined with additional plant information, the system can be used to generate additional useful control information.

Jan 1, 2005

By Shu Yamaguchi

The behavior of halide impurities in pyrometallurgical processes such as Wealtz kiln and MF process has been discussed based on the thermochemical data and the reported data of PbO activity in PbCl2-PbO melts. The role of PbCl(g) has been estimated to be significant in the chloridization evaporation reaction. From reported data on the PbO activity in PbC12-PbO melts, activity of PbCl2 has been calculated by the numerical integration of Gibbs-Duhem equation, and the stability domains and the composition of the liquid phase as well as the vapor pressure of PbCl2 have been estimated as functions of log P2HCI/PH2O and temperature. From the discussion of the path during cooling process on the log P2 HCI . PH2O vs. temperature diagram, the authors proposed a possible dechioridization process that utilize water vapor as a dechloridizer for the direct precipitation of PbO from gas phase.

Jan 1, 2003

By B, T Norgate, S Sanetsis, R Davidson

Global cement production accounts for about five per cent of man-made CO2 emissions (WBCSD, 2002). Such operating practices will increasingly be considered unsustainable, unless significant reductions in environmental impact can be realised by the industry.Slag is a high volume waste product from ironmaking, with about 300 kg of slag being produced per ton of iron. Critically, one ton of slag waste, if used as a replacement feedstock for Ordinary Portland cement (OPC), can prevent around one ton of emitted CO2 since no calcining is required. Slag cement blends can also show superior properties compared to OPC, such as lower heats of hydration and higher late strengths, but more development is needed to overcome their low early strengths. Rapid quenching of molten slag is required to produce æhydraulically-activeÆ binder when reacting with OPC; but water quenching can also require between five to ten tons of water per ton of slag at the plant. æDryÆ granulation (atomisation) is emerging as an alternative technology, the resulting solid product does not require drying, and possibilities exist for recovering heat energy from the hot slag.CSIRO Minerals has well-developed skills and equipment in pilot-scale pyrometallurgical treatment, and granulation of molten slag, including traditional wet, and also dry methods. Techno-economic desktop studies can also be used to help quantify factors such as value-adding of treated waste products, potential reductions in CO2 emissions and carbon credits, reductions in water consumption, and the possible decreased energy costs associated with fine grinding of dry slag granulate.The authors will present preliminary results from slag atomisation/dry granulation testwork (0.5 - 2.5 kg scale) and associated modelling studies, conducted using a æsyntheticÆ and industrial ironmaking slag. Outcomes from a techno-economic study on production of cement utilising wet or dry atomised slag granulate will also be discussed in detail.

Jan 1, 2004

The schlieren technique describes an optical analysis method designed to enhance light distortions caused by air movement. The ability to visualize air flow has significant implications for analyzing underground mine ventilation systems, including the enhancement of surveys and models. Currently, traditional schlieren methods are impractical underground. Background oriented schlieren (BOS) provides a solution to this problem. BOS requires two primary components, a professional quality digital camera and a schlieren background. A schlieren background is composed of a varying contrast repetitive pattern, such as black and white stripes. This background allows the camera?s sensor to capture minor light diffractions, such as those caused by air flow. Although BOS shows great potential for ventilation analysis, sensitivity is an issue. This paper seeks to validate the BOS technique for imaging flow through a regulator by comparing BOS images with traditional schlieren images. This paper also outlines initial experimental efforts used for the validation.

Jan 1, 2011

By AIME AIME

HOLDING the annual dinner-dance of the Institute at the Waldorf-Astoria had become such a tradition that there was widespread regret when it became known that the demolition of the building to make way for a huge office structure would perforce bring to an end the long and enjoyable series of gatherings our Institute had held there. This year the . Commodore was the place at which it was held and the commuters on the New York Central and the New Haven railroad systems, at least, found it a more convenient place for them. Except for the famous "Hoover" dinner, which will probably set a mark for all time, it was the largest dinner the Institute held, 1000 being present, and it taxed the facilities of the hotel to the utmost.

Jan 1, 1930