Search Documents

The aim of this investigation was to study the influence that varying production rates have on iron sinter quality. This was done by performing sinter pot tests at different pressure drops over the sinter bed, namely 11 kPa and 15 kPa (for 500 mm total bed depths). During each of the sintering processes temperature-time profiles were recorded of the top, middle and bottom layers of the sinter bed. On completion of the sinter process the sinter cakes were divided into top, middle and bottom layers. The physical properties of each layer were subsequently characterized by performing a tumbler test and a sieve analysis. A comprehensive mineralogical study was also conducted on each layer. This study revealed that sinters of similar cold strength could be produced under the examined production rates. However, a higher production rate was accompanied by an increased amount of fines. The cold strengths of both sinters significantly increased from the top layer to the bottom layer of the sinter bed. This strength variation is not related in any simple way to the phase composition. Keywords: Sinter, sinter bed, production rate, phase composition, cold strength, tumbler index, sieve analysis, temperature-time profile

Jan 1, 2003

By J. R. Piper

“Old Borate,” located in the Calico Mountains east of Barstow, California, lead domestic colemanite production from 1884 through 1907. Mineral exploration at “Old Borate” in the early 1980's, examined borate mineralization in Tertiary lacustrine strata. Surface sample and drill hole locations, geology and structure, were hand-drafted on paper maps. To re-evaluate this data, the information was digitized using Geographic Information Systems software. Digital Elevation Model based terrain modeling integrated surficial samples with drill hole data to locate favorable drilling targets. Structural relationships were used to identify hypothetical resources formed by the leaching of boron from surface exposures, redeposited at depth.

Jan 1, 2001

By M. du Plessis

This paper describes the evaluation of a limit equilibrium model to simulate the behaviour of crush pillars in platinum mines. An analytical model was derived to calculate the residual average pillar stress (APS) values of the crush pillars. The values predicted by this model were compared to the numerical values obtained from TEXAN simulations. In general, the limit equilibrium model appears to be very attractive for simulating pillar failure as the gradual crushing of the outside of the pillar and the transfer of stress to the intact core can be replicated. The value of the TEXAN crush pillar model was further demonstrated by simulating an idealized layout with crush pillars between two adjacent panels. The simulations illustrated that oversized pillars will not crush close to the face and this may lead to seismic failure in the back area. An important finding of the study is that closure measurements may prove to be a very valuable diagnostic measure in crush pillars layouts. Distinct differences in magnitudes of closure were simulated for a scenario where the pillars crush as expected, compared to the scenario where an oversized pillar is left. Experimental closure data collected in a crush pillar stope provided further evidence regarding the value of closure measurements in these layouts.

Jan 1, 2011

By David Chapman, Glen Frank

Due to the transport mechanics of the depositional environment, glacial soils display a very wide range of grain sizes and behavior. Several nonstandard drilling, sampling, and analytical techniques are therefore required to characterize the subsurface. The paper summarizes the geotechnical investigation for the design of a large project in glacial geology, which will include both large and small diameter pressure balance tunneling. The paper focuses on the challenges presented by the glacial environment and the techniques required to identify and characterize it for design and contract document preparation.

Jan 1, 2001

By Francis E. Federspiel

In 1984 and 1985, at the request of the U.S. Forest Service, the U.S. Bureau of Mines examined the 87,720-acre South Boise Yuba study area (formerly known as RARE II Wilderness Recommended area I-4553) to evaluate mineral resources. The study area and additions are in Blaine, Camas, and Elmore Counties, 10, about 60 mi east of Boise. Granitic rocks of the Cretaceous age Idaho Batholith occupy the western two-thirds of the study area. A Tertiary age granitic complex has intruded, and broken into small blocks, Paleozoic age sedimentary rocks in the eastern third of the study area. Tertiary Challis Volcanics overlie both of these rock types. Principal mineralized structures are gold-and silver-bearing quartz veins and shear zones trending northwest to easterly in the Cretaceous granitic rocks. Copper, lead, and zinc are accessory metals in many mineralized structures.

Jan 1, 1987

By S M. Loewen, J J. Fuykschot

Located in the north-west of Kazakhstan is a world-class podiform chromite deposit. Donskoy mining and beneficiation complex (DGOK), a branch of Kazchrome TNC, which is a subsidiary of the Eurasian Resources Group (ERG) operates two underground mines in this area, one of which is the ‘10th Anniversary of Kazakhstan Independence’ (DNK) mine.The mine currently applies the gravity caving mining method, producing 1.8 Mt/a of ore utilising a slusher layout and rail transport to the hoisting shafts. The deeper zones form the largest mineral resources at the DNK mine and are planned to be developed in the next several years. At this depth, the generally poor ground conditions, combined with the high in situ stress state will potentially lead to extremely challenging mining conditions.This paper describes a technical study undertaken by SRK to determine the possibility of increasing the maximum production rate from the currently envisaged 6.0 Mt/a to 7.2 Mt/a, and to reduce the time taken to steady state production.Based on a newly created 3D model, the inclined caving method was proposed for the largest orebodies. This method, presently not implemented at any operating mine, although planned for two other projects, was deemed very suitable to deal with the weak rock mass characteristics and the plunging morphology of the mineralisation.Dassault Systèmes’ GEOVIA’s Footprint Finder software (a module of GEOVIA’s PCBC™) was used to determine the caving zones and production schedules. The total mine design was completed in Deswik software, and resulting schedules combined in Excel.In addition to the use of an inclined caving method, several other suggestions were made to increase the productivity of the mine, such as the application of a conveyor belt system transporting multiple material types, teleremote technologies and the application of thin sprayed liners to reduce the swelling of the rock mass.CITATION:Fuykschot, J J and Loewen, S M, 2016. Inclined caving option for the DNK mine, Kazakhstan, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 669–682 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By A. B. Hooker, L. C. IlsLey

Explosives have been fired electrically for several decades. Mountains have been tunneled, deep shafts sunk, extensive coal and metal mine workings excavated and, in times of war, railroads, buildings, bridges, and fortifications have been destroyed by means of electrically fired explosives. Modern engineering depends so much on explosives that their safe and efficient handling and especially their detonation are of prime importance to all those connected with the use of explosive agents. Electric shot-firing is only one method of igniting explosives, but it is rapidly spreading and because of certain inherent safety features should be encouraged. Data collected by the Bureau of Mines indicate that in the United States a large percentage of the blasting in quarries, shafts,· and tunnels, and from 15 to 25 per cent of the blasts in mining operations, are set off electrically. The Bureau of Mines is interested in electric shot-firing because of its use in mining, and especially because electric methods, when properly applied, are undoubtedly safer than other methods commonly used. Electrical problems of many kinds must be solved in dealing with the various phases of electric shot-firing. Success in using an electric detonator is closely linked with the resistance of its bridge, the resistance of its leg wires, and the insulation of its current-carrying parts. The proper layout of a circuit where a number of shots are to be fired simultaneously depends not only on the types of detonators that are used and their arrangement and interconnections, but also on the size and insulation of the wire leading back to the source of power, and even on the source of power itself. Various types of electric shot-firing machines have been developed, and these offer still another field for study. In investigations of electric detonators and electric blasting equipment, the oscillograph is valuable because it can record electrical activity over very short intervals of time. By its use more complete information about electrical performance can be obtained than by any other means.

Jan 1, 1926

By T. Celik, B. Genc, C. Musingwini

"Mine planning software continues to be an important factor when it comes to the development of the South African mining industry. To contribute to this development, a new methodology to define and measure mine planning software utilization in the South African coal mining sector within an evolving data-set framework was developed. An initial data-set showing the mine planning software providers, their corresponding software solutions, as well as the software capabilities and information on the number of licences was collected and compiled in 2012 in an online database for software utilized in the South African mining industry. Details of the database development and implementation were published in the Journal of the Southern African Institute of Mining and Metallurgy in 2013. In 2014 the data-set was updated with additional and new information.In this paper, using the 2012 and 2014 time-stamps, a methodology for estimating the software utilization is developed. In this methodology, three variables: commodity, functionality, and time factor are used to define and measure the software utilization in order to ultimately inform decision making strategies for software utilization. Utilization in the coal sector was measured according to six different functionalities, namely Geological Data Management, Geological Modelling and Resource Estimation, Design and Layout, Scheduling, Financial Valuation and Optimization. The methodology is useful for stakeholders reviewing existing software combinations or intending to purchase new software in the near future and wanting to estimate the comparative attractiveness of a certain software package. These stakeholders include mining companies, consulting companies, educational institutions, and software providers. The work presented in this paper is part of a PhD research study in the School of Mining Engineering at the University of the Witwatersrand."

Jan 1, 2016

By S. G. Ercelebi

In surface mining operations, truck haulage is the largest item in the operating costs, constituting 50 to 60% of the total. In order to reduce this cost, it is necessary to allocate and dispatch the trucks efficiently. This paper describes shovel and truck operation models and optimization approaches for the allocation and dispatching of trucks under various operating conditions. Closed queuing network theory is employed for the allocation of trucks and linear programming for the purpose of truck dispatching to shovels. A case study was applied for the Orhaneli Open Pit Coal Mine in Turkey. This approach would provide the capability of estimating system performance measures (mine throughput, mean number of trucks, mean waiting time, etc.) for planning purposes when the truck fleet is composed of identical trucks. A computational study is presented to show how choosing the optimum number of trucks and optimum dispatching policy affect the cost of moving material in a truck-shovel system. Keywords: Open pit mine, equipment selection, dispatching, linear programming, closed queuing network theory

Jan 1, 2009

By K Gordon, A Black

Two remediation strategies have been considered to reduce the levels of acidity and dissolved metals in acid mine drainage discharging from Sullivan Mine, West Coast, New Zealand. The oxidising strategy involves adding alkalinity and dissolved oxygen (DO) resulting in the precipitation of metallic oxides and decreased acidity. The reducing strategy involves removing DO, resulting in the precipitation of metallic sulfides, followed by addition of alkalinity to decrease acidity. Field remediation trials indicate a reducing system may be more effective for this site than an oxidising system. A residence time of only two hours in the limestone layer of a successive alkalinity producing system (SAPS) is sufficient to reduce acidity by 100 per cent, iron by 71 per cent, aluminium by 59 per cent, nickel by 38 per cent and manganese by 26 per cent. The proposed remediation plan will likely include a series of SAPS, followed by an anoxic limestone drain, and settling ponds to capture any remaining precipitates.

Jan 1, 2003

By Shepherd J

Megascopic and microscopic studies of cleats and mining induced cleavage in Ihe first workings at Leichhardt Colliery reveal the presence of four distinct fracture sets. Microscopic studies confirm underground observations of the fracture sets.The most likely order of formation of the fractures is (i) "butt" cleats (ii) facc cleats (iii) shallow dipping faults (iv) mining induced cleavage. Three fracture sets apparently formed by tensiIe failure. Microscopy shows that the mining induced cleavage surfaces have preferred starting or lerminating points at the extremity of a "butt" cleat and a vitrite-dull coal band boundary. It is postulated that the induced cleavage begins at 'butt' cleats which behave as Griffith flaws under high compression around Leichhardt Colliery faces. Instantaneous outbursts of coal and gas are associated with only those workings which are affected by mining induced cleavage and occur at or adjacent to working faces.

Jan 1, 1981

By J P. Sykes, T C. McCuaig, M Jessell, A Trench

The election of Donald Trump and the Brexit referendum herald a shift towards a tighter definition of economic value, at the expense of the broader value concept of sustainable development; as well as a rise of protectionism, reversing a long-term trend of globalisation. However, the situation is complex, especially over the longer term in which mine project development and exploration operates. The minerals sector should proceed with caution. A greater focus on the local impacts of mining may be strategically beneficial, not only to mitigate against a potential protectionist future, but also because sustainable development has become more ‘localist’ via the concept of ‘social licence to operate’, whilst globalisation also seems to provoke increased ‘localist’ sentiments (known as ‘glocalism’). Localist strategies, therefore, seem a good hedge against multiple political futures. By contrast, moving away from sustainable development appears strategically riskier. Not only are ‘unsustainable’ activities, such as pollution and civil rights infringements harder to reverse, but a movement towards a more sustainable global economy may already be predetermined, even if the journey there may seem oblique. It appears that the increased economic development that is coveted globally is intrinsically linked to a rise in environmental and social consciousness.CITATION:Sykes, J P, Trench, A, McCuaig, T C and Jessell, M, 2017. Charles Dickens on the (potentially) changing role of globalisation and sustainability in the long-term future of mining and exploration, in Proceedings Tenth International Mining Geology Conference 2017, pp 239–256 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 20, 2017

By G. O. Rading, B. O. Odera, M. J. Papo, R. Couperthwaite

"Platinum-based alloys are being developed with microstructures similar to nickel-based superalloys for potential high-temperature applications in aggressive environments. Since the chemistries of nickel and platinum are similar, Pt-based alloys can be made with gamma prime ~Pt3Al precipitates in a gamma (Pt) matrix. Currently, the Pt-Al-Cr-Ru system is one of the bases for developing Pt-based alloys, where Al allows the formation of thePt3Al precipitate and also gives protection from the alumina scale formed, Cr provides oxidation resistance and stabilization for the L12~Pt3Al phase, and Ru provides solid solution strengthening in the (Pt) matrix. Four Pt-Al-Cr-Ru-V and two Pt-Al-Cr-Ru-V-Nb alloys were made, with compositions based on a quaternary alloy, ~Pt82:Al12:Cr4:Ru2, which hadpreviously been identified as having optimum properties. Four of the as-cast alloys had the targeted two-phase structure of ~Pt3Al and (Pt), and two were single-phase ~Pt3Al. Vanadium partitioned more to (Pt) than to~Pt3Al. There was an improvement in hardness compared to the quaternary alloys. The best addition of V was ~15 at.%; higher additions resulted in brittle intermetallic phases of the Pt-V system. The effect of Nbcould not be ascertained because of its high losses."

Jan 1, 2015

By J. R. Menasce

Mechanization in low-stope panels situated in hard rock infers roof support by tensile bolting to allow free passage of trackless mining equipment in the production areas. This is in sharp contrast to conventional mining, where compressive roof supports?such as timber and grout packs?have traditionally been used, up to 1.5 metres from the production face. Bolting is a hazardous operation because material is dislodged from the roof during the drilling activity. Even with temporary roof support installed, small pieces of rock are dislodged by the percussive action of the drifter. Operations with the man situated directly under the drill, during the drilling activity, are hazardous. The only way to remove the hazard is to move the man away from the machine for as much as possible throughout the complete cycle Costs associated with safety cannot be quantified, but need to form part of the decision-making process. Machine selections based on purchase and running costs alone do not justify the investment cost of mechanized bolters. The equipment selection process needs to take into account the total cost of mining as well as the human safety impact and loss of production costs from having to re-bolt roofs in a production panel to prevent falls of ground. Labour costs in mechanized low-stope bolting are between one-quarter and half the labour costs of non-mechanized bolting. This paper reviews the mechanized bolting option versus handheld bolting from a mining process and cost perspective in a hard rock, low-stope room-and-pillar mining operation in the platinum and chrome industries.

Jan 1, 2006

By C. Machio

This paper reports the results of a study to determine the effect of process control agent (PCA) on the characteristics of Ti-Mg powders during milling. It has been shown that a 2% increase in PCA content leads to up to a 40% increase in yield of the milled powder but reduces the kinetics of the mechanical alloying process. The introduction of 4% PCA decreases the mean powder particle size by up to 30%, whereas 6% PCA increases the mean particle size by up to 230%. The characteristics of the milled powders will be discussed in relation to the role of PCA in the milling process. Keywords Titanium?magnesium, mechanical alloying, PCA.

Jan 1, 2011

By E Villaescusa, A Kusui

The depth of underground mines has been increasing due to several factors, such as material demand growth and improving technology. It is a challenge to understand severe failure mechanisms such as spalling, which is caused by induced high stress. To investigate this failure mechanism under high stress conditions, intact rock blocks with small size tunnel were tested at the Western Australian School of Mines (WASM). The range of rocks, such as sandstone and granite, were drilled (200 mm hole) and tested using a servo-controlled 450 t capacity INSTRON machine. The acoustic emission sensors were attached to the block mass during the experiment to investigate the seismic response prior to spalling failure. The effect of the ground support system towards the failure was also examined by comparing the seismic response of the various ground support schemes.CITATION:Kusui, A and Villaescusa, E, 2016. Seismic response prior to spalling failure in highly stressed underground tunnels, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 689–694 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By G. W. Jones

In a previous report'/ results were given and a method outlined whereby from a knowledge of the composition of the natural gas and of the inflammability limits of the individual constituents composing the natural gas, the limits of inflammability of natural gas and air mixtures could be closely calculated. This method is based on the application of Le Chatelier's law as modified by Coward, Carpenter and Payman,5/ to apply to a mixture of any number of combustible gases. This law must not be used indiscriminately, because many exceptions have been found. For example, when ethylene, acetylene, hydrogen sulphide, or chlorinated hydrocarbons are present the law may not hold. For a discussion of the many exceptions which have been found, reference should be made to a report by Coward and Jones.6/

Jan 1, 1933

By M. J. Beus

A shaft is truly the "lifelinen of an underground mine. Damage to the shaft lining and guides as a result of ground movement can result in serious loss of production and extensive and continual repair. In some mining districts, annual shaft repair and maintenance costs resulting from high rock stresses and excessive displacement are in the millions of dollars per year. For many years, the Bureau of Mines has conducted research to characterize the rock mass and to develop structural guidelines to improve the design of accessways in deep mines. Much of this work has centered on determining the in situ conditions that affect the structural stability of shafts in the Coeur d'Alene Mining District of northern Idaho. Recent work by Beus and Board (1984) has concentrated on measuring the rock and support behavior during sinking of the Silver Shaft at the Lucky Friday Mine. These results are currently being used as a comparative data base for further basic research as well as to establish structural design criteria. The factors affecting the deign and structural stability of deep mine shafts are numerous. A design approach that use field data as input and directly compares field measurements with numerical models can validate the procedure and provide realistic design criteria. Naturally occurring "fixed? conditions such as magnitude, direction, and ratio of in situ stresses, geologic environment, and physical properties and constitutive relationships of the rock mass ere obviously basic to numerical modeling.

Jan 1, 1989

By Jacek Paraszczak

Numerous problems encountered in the mining of narrow vein deposits challenge the productivity, competitiveness and profitability of many mines. Mechanization of mining operations is one of the most important means to ensure the healthy survival of this mining sector. Vein deposits account for nearly all the world's primary silver production, as well as a significant portion of gold, tin, copper lead and zinc. In North America, narrow vein mining constitutes an important sector of the industry. Operators exploiting such deposits are concerned with the most appropriate mining method and equipment to mine in such a way as to minimize waste rock dilution. Unfortunately, most of the equipment available does not meet the additional geological and economical restrictions typical of narrow vein mining. Thus, mining these deposits is labor intensive and can result in low productivity. Consequently, the profitability of many such mines is reduced. Increased mechanization is one of the solutions to ensure their healthy survival. This paper reviews the state-of-the art in mining equipment with reference to narrow vein mining limitations. Problems encountered Geological conditions and economical factors have a decisive impact on the choice of mining method and equipment. Many ore bodies are relatively small, usually erratically distributed, often less than 2 m (6.5 ft) wide, with dips ranging from 0° to 90°. To make things worse, ore body limits are sometimes difficult to determine and the ground is hard and abrasive.

Jan 1, 1992

By M. C. Bétournay

Strainbursts are common in overstressed brittle rock around deep mine openings. Such failures are characterized by a biaxial state of stress in the plane of the opening boundary. A zone of compressive stresses imposes initial failures near or at the surface of the opening that results in spalling of thin slabs of rock roughly parallel to the free face. While the failure of rock under biaxial loading conditions is increasingly common in deep underground mines, only a few representative laboratory studies have been reported in the literature, without emphasis on rockbursting aspects, and none in the last decade. This paper presents the results of a testing program on a granite rock type. Biaxial testing, conducted on 100 mm cubic samples, was carried out to examine the influence of lateral confinement and loading rate on the rock’s ultimate strength. The paper reports the test results in terms of normalized biaxial failure envelope s1/sc-s2/sc. A discussion of the failure mechanisms observed is presented. Les coups de toits de déformations sont choses communes dans le rock cassant surcontraint en place autour des ouvertures minières profondes. De telles ruptures sont caractérisées par un état de contraintes biaxiales dans le plan de la périphérie de l’ouverture. Une zone de contraintes compressives impose des ruptures initiales à ou près de la surface de l’ouverture, qui produit des relâchements de minces plaques de roc plus ou moins parallel à la surface. Bien que les ruptures de roc sous des conditions biaxiales sont de plus en plus communes dans les mines à grandes profondeurs, il n’y a eu que quelques études représentatives en laboratoire de publiées, sans emphase sur des aspects de coups de terrains, et aucunes publiées depuis la dernière décennie. L’article présente les résultats d’une campagne d’essais appliquée à un type de granit. La campagne d’essais biaxiaux, sur des échantillons cubiques de 100 mm, avait pour objectif d’examiner l’influence du confinement latéral et le taux de chargement sur la résistance ultime du roc. Cet article fait part des résultats en terme de l’enveloppe de rupture biaxiale normalisée s1/sc-s2/sc. Une discussion sur les mécanismes de ruptures observés est présentée. Dehnungsbrüche findet man häufig in übergespannten spröden Felsen um die Öffnung von tiefen Minen. Solche Brüche sind von einer zweiachsigen Spannung in der Ebene der Grenze der Öffnung charakterisiert. Eine Zone von Druckspannungen verursacht initiale Brüche, entweder an der Öberflache der Öffnung oder in der Nähe. Davon scheiden sich dünne Felsplatten mehr oder weniger parallele mit der freien Wand. Obwohl Felsbrüche unter zweiachsiger Beanspruchung immer mehr häufig in tiefen Minen beobachtet sind, hat man über nur einige repräsentative Laborversuche in der Literatur berichtet. Diese Studien diskutieren das Thema ohne Betonung auf Felsbrüchen, und keine sind in den letzten zehn Jahren erschienen. Die vorliegene Arbeit gibt die Ergebnisse eines Testprogramms auf einem Typ von Granitfels. Durch zweiachsige Prüfungen von kubischen Proben mit Seitenlangen von 100 mm sollte man den Einfluss von seitlicher Ermittlung und der Beanspruchungsrate auf die Bruchfestigkeit des Felsen studieren. Man findet auch die Prüfergebnisse in bezug auf das normalisierte, zweiachsige Bruchkriterium s1/sc-s2/sc. Die beobachteten Bruchmechanismen sind auch diskutiert.

Jan 1, 2003