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By Michael Bowker

Au/TiO2 catalysts were prepared by incipient wetness impregnation and tested for the room temperature photocatalytic reforming of methanol in aqueous solution. These catalysts proved to be more active, on a molar basis, than Pd/TiO2. The dependence on loading of gold was different from that of palladium, showing a double maximum in yield at 0.1 and 2 wt. % with low rate below 0.01% and above 10%. A model is proposed for the reaction involving band gap excitation of titania electrons which are used to oxidise the methanol via adsorbed CO. With palladium, photoreforming of CO and water can be achieved, but this is much less effective on gold, presumably due to the much weaker bonding of CO on Au.

Oct 1, 2003

By S. Rash Ahmadi

Welding is highly reliable and efficient metal joining process. In welding the metal adjacent to the weld joint is subjected to severe thermal conditions. As a result, complex changes in metallurgical structure occur in this region. These changes in structure depend on the material and the temperature history experienced. Friction stir welding (FSW) is relatively a new welding process in which, heat is generated by friction between the tool and the workpiece. The amount of heat conducted into the workpiece determines the quality of weld, residual stress and distortion of the workpiece. The objective of the current work is to study the transient temperature in a friction stir welding. So, a three dimensional transient analytical model is used to study the thermal distribution during the welding. Heat input from the tool shoulder alone is considered in the model. The process parameters like axial load, welding speed and tool rotational speed, used in actual FSW process are taken to build the model. This analytical model is very useful for select the optimized affected parameters in friction stir welding. The model illustrates the comprehensive equation including actual affected parameters in FSW and it can be used for different materials. In addition to the above the thermal history finds application in design of welding tools.

Oct 1, 2011

By Jun Dai

Based upon research findings from several countries, the combination of microwave and mechanical means to break hard rock holds promise for the future. To achieve this goal, it is essential to understand the laws governing strength reduction of hard rock, such as granite, induced by microwave irradiation. Two aspects to consider are: 1) laws associated with the tensile strength of hard rock after microwave irradiation and 2) the sensitivity of different types of rock strengths to microwave energy. In this study, granite with a range of tensile strengths was exposed to microwaves for various time periods to compare the response of rocks with different strength values exposed to the same microwave irradiation. In addition, a method based on hotspots is presented to explain the mechanism by which granite strength is reduced by microwave irradiation. Granite extracted from Qinling Mountain in Shaanxi Province, China is used in the research. ?50 × 50 mm cylindrical granite specimens were exposed to microwaves at a specific power level. The strength values of the heated granite specimens were compared with those of unheated specimens. Through the comparison and analyses, relationships were determined between 1) reduction in granite strength and microwave irradiation time period, and 2) granite strength and sensitivity to a given energy of microwave irradiation. Finally, a mechanism to explain the experimental results is proposed. Research findings will aid in the design of a microwave + machine rock-breaking system for use in rock breakage in underground mines at depth and for future mine applications on earth and other planets. In addition, the experimental approach could be used to test other rock types to further our understanding of rock damage induced by microwave irradiation.

Aug 1, 2013

By A. M. Nordale

Let us first trace a line, mentally, across Alaska and Yukon, starting at a point in the west slightly south of the delta of the Yukon river and from there continuing eastward, loosely following the 63rd parallel of latitude until we have passed beyond the eastern border of Yukon. We will make two pronounced digressions southward to include the greater parts of the Iditarod and Tanana River valleys. That visualized line roughly defines the southern boundary of permafrost. North of it lies a vast region, fully three-fourths of the area of the two territories, which includes Seward peninsula, the great Yukon River basin, and the tractless wastes of the Arctic. During some frigorific cycle in the distant geological past, the ground there was frozen to a depth of many hundreds of feet. How deep the frost actually penetrated is not known, but it has been found to exceed three hundred feet in many places. Nature afterwards provided a perfect insulating cover in the form of heavy moss and dense grass, which has protected the ground from the heat of the sun's rays during the intervening ages. This frozen condition has always been accepted as something indigenous to the North and little thought was given to -it until recently, when the United States Government and, I believe, the Canadian Government, began extensive studies of it, particularly in respect to its effect and bearing on the development of the great oilfields of the Arctic. Within this large region and but a short distance south of the Arctic circle are the three principal producing placer gold fields in the sub-arctic, whose hubs centre at Nome and Fairbanks in Alaska and at Dawson in Yukon Territory. The geological structure and history of the gold-bearing deposits of Dawson and Fairbanks are very similar and probably closely related. They are typical placer deposits produced by stream action during periods of erosion and inundation and subsequently covered with a thick layer of fine, powdery silt mixed with decayed vegetation which, locally, is termed 'muck'. The depth of muck varies from less than 10 to more than 250 feet, with the greater depth near the lateral edges of the valleys. The gravel underlying it is medium in size, well rounded, and composed mostly of quartz and schist. The proportion of sand or fines is approximately 40 per cent. No large boulders and little clay are found, for those districts, as well as that of Nome, have not been subjected to glaciation. The most common bed-rock found is either decomposed or hard schist, but infrequently it is slate, quartz, diorite, or a porphyry. The vertical concentration of the gold is invariably on bed-rock and in the lower few feet of gravel which overlie it. The horizontal concentration or paystreak is roughly parallel to the trend of the valley but does not ordinarily coincide with the course of the present stream. The width of the paystreak usually expands from a few feet at the head of a creek to several hundred feet near its mouth.

Jan 1, 1947

By Tom Demorest

SMART is an association of mining companies that meet regularly to coordinate the technology development needed by the mining industry. Since 1995, the member companies and institutions have directed research and influenced the manufacturers and suppliers to improve surface mining technology and services. SMART actively supports learning seminars, collaborative research projects, and user groups. Members of SMART include some of the major surface mining companies in North America and Australia. These companies have recognized the value that collaboration can bring to the needs of individual organizations as well as the global mining industry.

May 1, 2009

By Morris Wong

"An antimony-bearing gold ore was studied in a cyanide slurry containing 7 -20 ppm dissolved oxygen. 1 g/L NaCN at pH 9.5 and 48 hours retention time is required to extract 94 % of the gold from the 90 % minus 200 mesh ore by conventional cyanidation at a 7 ppm O2. As oxygen concentration was increased to 20 ppm, the conditions required to extract the same amount of gold were: 0.25 g/L NaCN, 16 hours retention time and 80% minus 200 mesh. Compared to conventional cyanidation, oxygen-enriched leaching was shown to reduce retention time by three times and cyanide consumption by four times. The kinetics of gold dissolution related to the dissolved oxygen concentration in slurry was expressed by following equation:XAu = 100 * (Kt + I0) / (1 + Kt + I0)where XAu is the percentage gold extraction; t is the retention time; K and Io are the slope and the intercept of the plot of XAu I (100 -XAu) vs. t respectively. The values of Kand Io depend upon the concentrations of cyanide and oxygen, the fineness of grind and the origin of ore sample etc.. A preliminary cost analysis was also performed to justify the use of oxygenating slurries.IntroductionGeneral:It was proposed almost 149 years ago (Elsner 1846) that oxygen is required for the dissolution of gold in cyanide solution. However, little attention were paid to oxygen application in the gold milling industry during the following one hundred years. Due to the constraints of gold price, reagent costs, refractory ores, and environmental issues in the past decade, the oxygen enhancement in the cyanidation process was introduced to the gold milling industry for increasing operation efficiency, reducing production costs, and meeting the requirement of environmental standard.The advantages of oxygen-enriched cyanidation have been reviewed by several investigators (Hague 1992, Jara et al 1992, Henderson 1989, Loroesch et al 1988, Elmore 1987, Cathro 1963). Common to all conclusions are the following advantages."

Jan 1, 1995

By Shek N. Lau, Nicola Samman

"Enclosed gear cases on board heavy mining equipment have traditionally been lubricated with regular heavy duty gear oils. However, equipment manufacturers, have recommended the use of an ISO-1000 gear oil for this application to ensure adequate lubricant film strength, especially at the higher end of the working temperature range. The majority of these ISO-1000 gear oils are based either on residual/asphaltic oil or synthetics, primarily higher viscosity polyalphaolefins. Although the performance of these lubricants has been satisfactory, they suffered other shortcomings that equipment users have lived with over the years.The major requirement at the user’s mine was to provide lubrication for the shovel Hoist gear case. Within such a gear case design, the gears and the roller bearings, that have different lubrication requirements, are lubricated with the same lubricant. Several lubricants were used, light gear oils as well as the recommended ISO-1000 heavy gear oils. On the one hand, the lighter oils performed adequately for the lubrication of the bearings that formed part of the enclosed gear system. These lighter oils did not perform as well for the lubrication of the gears due to their lower viscosities, resulting in shorter gear servicelives.On the other hand, the ISO-1000 gear oils performed well for the lubrication of the gears, but were too viscous to creep into the bearing elements to lubricate them adequately, especially during the cold northern Canadian winters. This resulted in catastrophic bearing failures and secondary damages to the gears.The challenge, then, was to formulate a lubricant which met the 1000 cSt at 40°C viscosity requirement as stipulated by the equipment manufacturer, while satisfactorily lubricating the bearings at the full working temperature range. This was achieved by the development of a semi-fluid grease lubricant, which has proven in field trials to give adequate performance in this application for the lubrication of both the bearings and gears down to -40°C.This product met the equipment manufacturer’s performance criteria and resolved, to a large extent, leakage of the lubricant through seals experienced with the use of conventional and synthetic gear oils.Although the main performance criteria of the fluid was its capability to lubricate the “Hoist” gear case, it was also used during the field trial in other gear cases on board the shovel to test its full capabilities.This unusual alternative lubricant was field tested and evaluated for more than two years. Based on this assessment, the product was reformulated to improve its fluidity, slumpability and the settling of debris/wear metals to the bottom of the gear cases. This reformulated softer grade, a semi-fluid grease, has been performing satisfactorily for more than eight months and is still undergoing longer term assessment."

Jan 1, 1996

By W E. vanSteenburgh

The Polar Continental Shelf Project was initiated in 1959 to provide an administrative and logistic vehicle for research in the physical sciences of the land, sea and channel area of the Arctic Archipelago. Most of the scientists are supplied on secondment from the professional branches of the Department. The yearly expeditions number some eighty scientists and sub-professional staff, and they are supported by a fleet of fixed-winged aircraft and helicopters. Accurate positioning is obtained by the use of a Decca Lambda navigational system which is moved as the area of interest is shifted. The Project is designed to accommodate not only physical scientists, but to provide facilities for other scientist who may have an interest in the area under study. The main research scope of the Project includes topographical surveys, hydrography, oceanography, geology, including marine sedimentary studies, gravity, magnetics, seismology, glaciology and geography. The Polar Continental Shelf Project was initiated and recommended by the Committee on Northern Development in 1958.

Jan 1, 1963

By Oliver Hall

WITH the friendly consent both of the Institution of Mining and Metallurgy, for whom this paper was written, and of the author, we had the pleasure of publishing Mr. Oliver Hall's paper on Mining at Noranda in our issue of last March and of having Mr. Hall present it at the Montreal Meeting. In the following pages we now report the discussion elicited by the paper at a meeting of the Institution in London on March 18th. The report is taken from the April, 1937, issue of the Bulletin of the Institution, to whom we again tender our thanks. THE PRESIDENT (MR. ROBERT ANNAN) said that this paper was, by arrangement with the Institution and the author, also being published by the Canadian Institute of Mining and Metallurgy for approximately simultaneous discussion. He was sorry that Mr. Oliver Hall could not be present to introduce it in person, for he was sure that the author would have had many more details to give about this most interesting mine. The paper contained a very useful account of mining operations, and personally he had been pleased to see the tri-dimensional projections of the orebody in Figs. 3 and S. It was a good illustration o the value of that method in presenting the form of an orebody such as this. While he had no desire to go into technical details, he wished to call attention to a remark in Mr. Hall's introduction, in dealing with the history of the mine and the principles on which it was run. The author had given an account of the early difficulties in solving geological problems, and later of the economic difficulties of seeing this mine through a period of intense depression in metal prices. He stated that it was clear that, to maintain income, tonnage must be increased, and, to maintain profits, costs must be decreased. It would be observed that there was no question of increasing the grade of ore. Then the author went on to say: 'Having set the house in order in the years of adversity, the higher price for gold is being used to mine to still lower limits and lengthen the life of the enterprise and the welfare of those dependent on it'.

Jan 1, 1937

By Matthew A. Baumann

Tooth wear on mining shovels presents a challenge for productivity. A shovel with worn teeth suffers from increased digging forces, longer fill times, and an increased likelihood of lost or broken teeth and adapters. Efficient maintenance planning relies on knowledge of tooth decay rates and patterns. A fully automated wear monitoring system can record detailed logs of tooth wear, permitting G.E.T. personnel to optimize maintenance scheduling. Studies have demonstrated that planned tooth change-outs result in significantly reduced costs as compared to unplanned maintenance. A machine-vision-based tooth-wear monitoring method is introduced. A rugged camera is installed on the boom of cable shovels, or on the stick of hydraulic shovels. The images are processed using a photogrammetric algorithm to determine the individual tooth lengths. Tooth length data is collected at intervals during shovel operations, forming a profile of the current wear state, speed of decay, wear pattern, and expected lifespan of teeth. A case study in a South American mine on a Komatsu PC8000 hydraulic front shovel is presented. Tooth wear is tracked over a 6-day period and wear rate statistics are computed for 6 teeth. This validates the system and provides an example of how wear patterns can be recorded and analysed by an automatic system. Armed with this data, mine personnel can reduce the cost and lost time due to unplanned maintenance, and observe the effects of mine conditions and operator behaviour on tooth wear.

May 1, 2011

By J. W. Reynolds

Use of crushed waste rock recovered by sink-float separation from normal ore production for backfill is an established procedure at Commco's Sulhvan mme, Kimberley, British Columbia. Need for a safe method of placement in voids which were difficult to reach by gravity methods led to a co-operative venture with Radmark Engineering Ltd. in the development of a workable pneumatic transportation system for rock material. This paper reviews work done to date in a current program, and includes comments on the nature of the fill so placed, options for cementing such fill, implications for other aspects of mining and references to other applications of the system by other organizations who exchanged experiences with the Sullivan mine staff during the five-year period reviewed.

Jan 1, 1972

"THE OTTAWA BRANCH, CIM, each year holds a symposium on a subject of topical interest. The symposium this year was on Canada's Offshore Mineral Resources, at which papers were presented by: Dr. Donald G. Crosby, chief, Resource Administration Di-vision, Department of Energy, Mines and Resources, Ottawa; John A. Beesley, head, Legal Division, Department of External Affairs, Ottawa; and David W. Smith, man-ager, offshore exploration and production, Shell Canada Limited, Calgary. Because of the interest which this topic holds for our members, and because of the wealth and significance of information presented, the three papers -representing the first comprehensive review of our offshore resources -are reproduced herewith. The opening remarks of the Chairman, Dr. F. K. North, Professor of Geology, Carleton University, are also recorded, together with a few of the questions asked by the large attending audience. The symposium was held February 13th, and was organized by Dr. W. M. Tupper, chairman of the Branch Program Commit-tee. Differences in the extent of the continental shelf will be noted in the papers. These differences are related to slightly different definitions of the continental shelf by the authors."

Jan 1, 1969

By N. Lecuyer

"During early 1980, pre-production work commenced at the ""Les Mines Gallen"" project, north of Noranda, Quebec. As a result of the acid mine water associated with this property, a major pre-production phase included the installation of a water treatment plant to render the water environmentally suitable.This paper emphasizes the planning, installation and operational factors of the treatment plant necessary to the success of the mining operations and the maintaining of a clean environment.Introduction,T he Gallen Project is a zinc, gold and silver open-pit mining operation approximately 10 kilometres north of Noranda, Quebec. This property has a long history, with initial diamond drilling done in the early 1930s and underground mining taking place between 1953 and 1962. This property was reactivated in 1980, with production scheduled a t a rate of 45,000 ton s per month.Included in the reactivation plans for the property was the installation of a water treatment plant to treat the acidic mine water.Plant DesignThe requirements for the Gallen water treatment plant were two-fold. Firstly, it was necessary to neutralize the acid water and secondly to produce a sludge containing metal hydroxides and sulphates which would be stable when stored, and a clarified overflow meeting governmental regulations to be discharged to the environment.The flow sheet (Fig. I) will explain the process in treatment of the acid water.Acid mine drainage is treated with lime to increase the pH to 9.50. Metals in solution are precipitated as metal hydroxides and the 504 as calcium sulphate. The precipitate slurry is then aerated to convert ferrous iron to ferric iron, which is more stable for storage and disposal.The precipitate is next flocculated with a polymer flocculant and settled in the thickener to produce a sulphate/Hydroxide sludge and a final effluent discharged to the environment."

Jan 1, 1983

By F. J. West

This paper deals with Jones & Laughlin Steel Corporation's new Adams mine, near Kirkland Lake, Ontario. After a brief discussion of ore structure, type, reserve tonnages, etc., the main body of the paper discusses the establishment of an open-pit limit based on economic considerations. The method used by J & L to arrive at an economically sound open-pit boundary its outlined fully. Physical limitations to open-pit boundaries are mentioned briefly. The paper concludes with a few remarks on the mining equipment in use and on its productivity

Jan 1, 1966

By Ted Nuorivaara

The use of polymer-surfactant mixtures as foam stabilization agents is a topic that has drawn the attention of several fields but has so far not be thoroughly studied in the context of mineral froth flotation. The present work showcases a study on the impact on flotation performance of cellulose surfactant derivatives and their mixtures with commercial frothers. Bubble size and foam property measurements were run in a two-phase system along with laboratory-scale flotation experiments conducted using a porphyry copper ore from a mine in Finland. A comparative analysis on recovery, grade and flotation kinetics is presented on the products obtained using: i) a partially hydroxylated cellulose derivative (i.e. hydroxypropyl methyl cellulose; HPMC), ii) a commercial polyglycol-ester frother (Nasfroth240; NF240), and iii) mixtures of these two. The results show that using frothers with a total concentration of 30 ppm, the HPMC-NF240 mixtures provide advantages in terms of Cu recovery, (i.e., up to 95%), compared to the use of either NF240 (ca. 76%) or HPMC alone (ca. 1%). Interestingly, only a small proportion of HPMC mixed with NF240 was sufficient to produce a measurable increase in recovery. This improved performance was attributed to a synergistic effect of the polymer-surfactant mixture which further reduced the bubble sizes in a two-phase system compared to that of NF240. The present work offers a further step into understanding the phenomena taking place when a short chained surfactant is either substituted or mixed with a cellulose derivative, offering potential ways of exploiting this behavior for the enrichment of minerals. INTRODUCTION Froth flotation has been the predominant technology used to beneficiate sulfidic copper minerals such as chalcopyrite ever since it was invented in the late 19th century. The reason for the domination of flotation technology lies behind its versatility in selective separation as well as relatively cheap operational costs (Wills & Finch 2015). Even though flotation of sulfidic copper minerals is moderately well understood based on the broad research work done around the subject (e.g., Albijanic et al., 2015, Bournival et al., 2017, Wang et al., 2015, Mikhlin et al., 2015, to cite only a few), the modern era presents new challenges to the primary raw material industry, including questions regarding sustainability of mining operations accompanied by a need to improve the process efficiencies due to declining ore grades (Edraki et al., 2014).

Jan 1, 2019

By G. A. Maki, P. J. Fullman, R. G. Roden

"In October 1984, Rocanville Division began using a stacking system to handle potash mill tailings. Previous to this date, mill tailings were slurried to the top of the tailings pile and allowed to debrine while flowing down the pile. With the new stacking system, slurried tailings are fed to mobile stackers. The stackers consist of cyclone packs to debrine the tailings and drag conveyors with screw discharges to deposit the tailings onto the existing pile. This paper deals with the various aspects of the project from conception to its present state.IntroductionPrevious to 1984, when the stacking project was first implemented, potash mill tailings were handled as follows. Mill tailings were first debrined to approximately 65010 solids using a cyclone cluster. The cyclone underflows were then introduced onto a vacuum scroll filter table. Here the tailings were further debrined and discharged into the disposal tank where the tailings were reslurried with reclaim brine and pumped to the tailings disposal site. At the disposal site the slurry was discharged onto the tailings pile and by a natural settling process the tailings were debrined with the brine ultimately collected in the reclaim brine ponds. The shape and profile of the tailings pile was controlled by building salt dykes to control the flow of the discharged tailings slurry. As the tailings pile grew in height, booster pumps were added to the disposal system."

Jan 1, 1990

By C. Barlow

The White Mesa Mill (WMM) began operating in 1980 as a regional processing mill owned by Energy Fuels Nuclear, Inc. Original mill design was for 656,000 Mtpa of U ore producing 1,250 tpa of U3O8 concentrate. Sustained market downturns delayed facility upgrades during most of the 1980s and 1990s. The new owners of WMM, Denison Mines, elected to advance the regional mill concept in 2007 with the modernization of these facilities. This paper details decisions taken and lessons learned in plant redesign, choice of leading-edge instrumentation, motor controls and process automation, training and some example benefits from process control stabilization.

Aug 1, 2010

By A. R. Farkoosh, K. Korgiopoulos, McGill University, O. Rodop, L. A. Villegas Armenta

"New generation of Al-Mg-Si alloys with thermally stable dispersoids that prevent recrystallization and grain growth during hot deformation are currently used in automotive components requiring good formability. Alloy chemistry controls the phase formation especially age-hardening precipitates, dispersoids, and primary intermetallic which have pronounced effect on grain structure, strength and formability. In this work, thermodynamic calculations have been used to predict the effects of varying levels of Si (0.5-1.5wt%), Mg (0.5-1.5wt%) and Mn (0.1-2.5wt%) on phase selection. Thermodynamic calculations have been performed in equilibrium and non-equilibrium conditions via the FactSage™ software using the FTlite database. Selected compositions have been cast, heat treated, extruded and characterized through scanning electron microscopy with energy dispersive spectroscopy and electron channeling contrast imaging techniques. The calculations showed that at the hot deformation temperature of ~540 oC, exceeding certain Mg and Si levels would lead to retained *-Mg2Si intermetallics and Si particles at the grain boundaries in addition to a-Al-(Mn,Fe)-Si. It was found that retained *-Mg2Si phase which adversely affects formability can be avoided for Si+2Mg levels lower than 2.3wt%. FactSage calculations also showed that increasing Mn from 0.5wt% to 1wt% leads to an increase in the amount of dispersoids (from 1wt% to 2wt%) that can potentially slow down recrystallization and grain growth during hot deformation and improve formability. Calculations at room temperature also show that for an alloy with 0.7wt% Mg, excess Si beyond 0.7 wt% promotes the precipitation of Si clusters in the Al matrix that accelerate natural age-hardening. Results were confirmed by experimental investigation.INTRODUCTIONAluminum alloy 6082 (Al-Mg-Si) is used in the automotive industry because of its high strength, and good weldability (I. J. Polmear, 2006). The alloy is age-hardenable through the precipitation of ß-Mg2Si and its precursors, and the recrystallization is usually inhibited by Mn- and Cr-containing dispersoids formed through high temperature heat treatments (I. Polmear & Couper, 1988). However, it is known that minor changes in alloy chemistry (Mg/Si ratio) can have significant influences on the ductility and formability of these alloys by altering phase selection and the resultant microstructure (Gupta, Lloyd, & Court, 2001; McQueen & Celliers, 1997; Zajac, Hutchinson, Johansson, & Gullman, 1994). For automotive applications where wrought alloys (usually extrusions) are cold-formed to produce suspension components, the chemistry of the alloys and the extruded structure are of crucial importance as they determine the formability at room temperature (Asensio-Lozano, Suárez-Peña, & Vander Voort, 2014). In this study, thermodynamic calculations along with experimental investigations were carried out on the Al-Mg-Si system to understand their phase formation and precipitation hardening as a function of alloy composition."

Jan 1, 2016

By D. Sharma, A. K. Singh, R. Singh, P. K. Mandal, M. Sarkar

"This paper deals with the stability investigations carried out at the XIVth seam of Jitpur colliery. The study was conducted to investigate the possible causes of roof cavity formation and face spalling at the middle slice face of block-3 longwall panel and to suggest remedial measures. The instrumentation and monitoring work was carried out in the panel over a period of nine months. On the basis of observations, it was found that if the maximum face span was reduced from the existing 4.8 m to 3.6 m, and if the face time schedule cycle was reduced from a maximum of 37 days to about 18 days, this problem could be eliminated. The recommendations of CMRI have been implemented in the middle slice face of block-4 panel with success. IntroductionModerate to steeply dipping, undisturbed seams of uniform thickness are worked by way of inclined slicing parallel to walls. In this method, the seams are treated as a combination of several moderately thick seams dipping parallel to roof and floor. Numerous variations of multislice mining have been used worldwide to get high coal recovery under local conditions of geology, subsidence control, proness to spontaneous combustion, statutes and economics. Multislice mining can proceed either downward descending from the roof or upward ascending from the floor. Ascending methods require backfill behind the working face to provide a base for the next slice. It is also adopted for surface protection against subsidence or mining under a massive roof. This paper presents a scientific study conducted in Jitpur colliery, IISCO where a 9 m thick seam is mined in three slices in ascending order with stowing."

Jan 1, 2002

By S. W. Henley

"Shaft sinking design is typically driven by what has been successful in the past and the availability of sinking plant. This document considers a project where the sinking design and methodology is unconstrained by conventional thinking and removed from the commonly held belief that a sinking methodology should be developed from available winding plant. Schedule was a key driver for the Project and led to an alternative sinking design that aimed to optimise sinking advance rates by specifying new winders that compliment known sinking plant while providing improved safety, redundancy and flexibility within each part of the sinking cycle. KEYWORDS Consistent, Efficient, Flexible, Improved, Innovative, Optimise, Redundancy, Safety, Schedule INTRODUCTION The project is remotely located in the South Gobi region of Mongolia on a brownfield site and the scope of work included the concurrent blind sinking and concrete lining of two (2) ventilation shafts to an approximate depth of 1,150 m at a finished diameter of 10 m and 11 m respectively. All sinking and lining operations to be completed as in-line activities, (no lining whilst other activities are undertaken). The project was schedule driven with a completion date set for the first quarter (calendar) of 2021 and there were no restrictions imposed on the successful Contractor with respect to their equipment selection. Existing sinking plant already onsite from three previous shaft sinking operations would be made available to the Contractor if required on an as is where is basis Sustained advance rates in excess of 2.4 m per day would be required in order to achieve the completion milestone, therefore the design would have to include contingency and demanded flexibility to account for equipment down time. Previous shafts that had been sunk onsite have utilised a single double drum kibble (bucket) winder (hoist) with a single excavator loading on the shaft floor into a large capacity kibble (bucket). DESIGN Mucking The sinking design centred on the mucking cycle given that this is traditionally the most restrictive part of the sinking cycle and typically accounts for one third of the overall sinking cycle. The Vertical Shaft Mucker (VSM) and/or diesel excavator are commonly used plant for shaft sinking that were under consideration. The use of Cactus Grabs was not considered given the higher risk associated with grab ropes and hoist failures."

Jan 1, 2019