Search Documents

By C J. Adams, H J. Campbell, A J. Tulloch, I J. Graham

New Zealand can be regarded as a rifted part of mineral-prospective eastern Australia. Geologically credible comparisons between selected trans-Tasman and SW Pacific geological provinces and units, especially those that contain significant mineralisation in Australia, can help provide a useful exploration framework for New Zealand. As part of a six-year Mineral Wealth of NZ and its EEZ (MWE) research programme, we have targeted selected geological units in eastern Australia for comparison and contrast with their potential New Zealand counterparts. In future years, the programme will focus on geological units in New Caledonia.

Jan 1, 2005

By Amauri Garcia, Rodrigo Valenzuela Reyes, Noé Cheung, José Eduardo Spinelli, Leonardo Fernandes Gomes, Rafael Kakitani

"The present research work deals with directional solidification (DS) of both Al-15wt.%Si and Al-15wt.%Si-1.5wt.%Mg alloys and further characterization of the related microstructures. The growth of refined primary Si and refined eutectic is well-known as positive in order to improve mechanical properties of the Al-Si based alloys. Alloying is also an effective method to strengthen the Al-Si based alloys, in which Mg is considered an important alloying element. However, lack of investigation regarding the effects of Mg on microstructure of these alloys is noted. So, in the present research work emphasis is given on both dendritic and eutectic growth being affected by solidification kinetics (V-growth rate and G-thermal gradient) during transient directional solidification. Experimental evolutions of microstructural spacing of both alloys have been determined which becomes possible to understand the effects of Mg coupled with the effects of growth rate on the final microstructural arrangements. A direct comparison of the tensile mechanical properties obtained for the alloys is also performed. It is shown by these correlations that the addition of Mg generally improves the tensile mechanical resistance with a minor decrease in ductility. Furthermore, the Scheil solidification path of the ternary Al-Si-Mg alloy was determined using the computational thermodynamics software Thermo-Calc, resulting in the following sequence of precipitation: Liquid-Si-a (Al)+Si- a(Al)+Si+Mg2Si. This sequence is compared with the experimental microstructure findings.INTRODUCTION Al-Si alloys containing from 4wt.% to 22wt.% Si comprise more than 90% of all Al-based castings. Parts manufactured with these alloys have a wide range of industrial applications due to their excellent castability, crack resistance, good corrosion resistance, good weldability, low density and high strength (Bray, 1976; Zolotorevsky, 2007; Reyes, 2017). Hypereutectic Al-Si alloys are widely used and researched in the automotive and aerospace sectors due to the low coefficient of thermal expansion, resistance at high temperatures, good wear resistance and high strength (Reyes, 2017; Tebib, 2013). Above the equilibrium eutectic composition (~12.5wt.%Si) the amount of primary Si particles becomes significant (Lasa, 2003). In the place of conventional hypoeutectic Al–Si, there is growing interest in hypereutectic Al–Si alloys as a candidate material for the high-quality engines because a higher volume fraction of silicon may bring about superior properties (Matsuura, 2003)"

Jan 1, 2017

By P Mitchell, J Proffett, I Munajat

Batu Hijau is an island arc porphyry copper-gold deposit located in the southwest corner of Sumbawa Island in the Sunda-Banda archipelago of Indonesia. Southwest Sumbawa Island is underlain by Early Tertiary, low-K calc-alkaline to weakly alkaline volcanic and intrusive rocks. Within the mine area the oldest exposed rocks are medium- to thick-bedded, medium to coarse andesite volcanic lithic breccia, thin bedded, fine-grained volcaniclastic sandstones and mudstones and hypabyssal porphyritic andesite. In the eastern portion of the mine area there is a thick sequence of quartz diorite that postdates the andesites. A small stock of Equigranualar Quartz Diorite predates the Batu Hijau deposit and occupies the contact between the andesitic volcaniclastic sequence of rocks and the Porphyritic Quartz Diorite. Batu Hijau is a world-class copper-gold deposit that has a drill indicated mineable reserve of 914 million metric tonnes grading 0.525 per cent copper (10.58 billion pounds copper) and 0.403 g/t gold (11.8 million ounces gold). Mineralised material not in reserve accounts for an additional 580 million metric tonnes at 0.328 per cent Cu (4.19 billion pounds copper) and 0.171 g Au/T (3.19 million ounces gold), and including an oxide copper resource of 57 million tonnes at 0.37 per cent Cu and 0.12 g Au/T. Copper and gold mineralisation is directly related to quartz veining and wall rock alteration that developed with multiple tonalite porphyry intrusions. The tonalites were emplaced along the contact between the andesitic volcaniclastic rocks and quartz diorite intrusives. Copper and gold are zoned around the porphyry intrusions, which are designated by their contact-age relationships and other features as Old Tonalite, Intermediate Tonalite(s), and Young Tonalite(s). The Old Tonalite was the first copper-bearing intrusion, and although it is the smallest intrusion it has the highest quartz vein density, the strongest alteration and the highest grade. At least two tonalite porphyry intrusions followed the emplacement of the Old Tonalite. Each of these intrusions was associated with less quartz veining, weaker hydrothermal alteration and lower grade copper and gold than the previous intrusion. The intrusive cycle culminated with the emplacement of the Young Tonalite, which contains relatively few quartz veins, is weakly altered and mineralised. Hypogene hydrothermal alteration and sulphide mineralisation developed in five temporally and spatially overlapping stages. These stages consist of Early, Transitional, Late, Very Late, and I Zeolite alteration. Early alteration and sulphide mineralisation accompanied each tonalite porphyry intrusion, but with diminished intensity in each subsequent intrusion. Transitional and later stages of alteration and mineralisation postdate the tonalite porphyries and overprint Early stage alteration and mineralisation. Early alteration and mineralisation consisted of biotisation, secondary magnetite and plagioclase development, fine porphyry-style stockwork veining and ore mineralisation. Magnetite-biotite????quartz stringers and dark micaceous (biotite-sericite) veinlets were developed. The veinlets were accompanied by biotisation of magmatic mafic minerals and groundmass. Thin, irregular and discontinuous æAÆ type quartz veinlets and fine-grained chalcocite, digenite and bornite mineralisation accompanies the Early alteration. It is hypothesized that most of the copper mineralisation was originally deposited as bornite, digenite and chalcocite. Secondary plagioclase was added along the selvages of the early quartz veinlets. Early alteration is pervasive within and proximal to the tonalite porphyries. In the distal portions of the deposit, andalusite and anthophyllite formed at intermediate to shallow depths, and in the deeper portions of the deposit, respectively. The andalusite and anthophyllite probably developed at the same time as the early magnetite-biotite-quartz alteration in the core of the deposit. Transitional-age alteration consists of oligioclase/albite-sericite-chlorite- quartz-¦vermiculite and is associated with æBÆ quartz veins. Through-going planar æBÆ veins are thicker than æAÆ and æA-familyÆ veinlets and have chalcopyrite????bornite along vuggy centrelines and narrow oligioclase????albite alteration envelopes. Rare æCÆ chalcopyite¦quartz veinlets were also formed during Transitional alteration. During Transitional alteration early copper sulphide minerals (chalcocite, digenite and bornite) are converted to bornite and chalcopyrite. The majority of the copper (50 - 70 per cent) in the deposit is contained in ores in which chalcopyrite is the predominant sulphide. Late alteration consists of feldspar destruction and replacement by sericite and other minerals. The late alteration is accompanied by the development of æDÆ sulphide veinlets and veins. These veins consist of pyrite and quartz????chalcopyrite. Within the halos of the late pyritic veinlets biotite is replaced by sericite, quartz-sericite, quartz-andalusite, or quartz-pyrophyllite+kaolinite replace plagioclase, and magnetite is converted to specularite and/or pyrite. In the periphery of the deposit, the feldspar destructive alteration, together with outer zones of Transitional-age alteration, constitutes what is commonly referred to as a æpropylitic zoneÆ. Very Late hydrothermal alteration is also characterised by feldspar destruction, but differs from Late alteration in that feldspar is replaced by smectite in association with sericite and chlorite. Sulphide mineralisation in this stage consists of sphalerite, galena, tennantite, pyrite and chalcopyrite. The last stage or I Zeolite alteration consists of low-temperature, open space filling consisting of stilbite or laumontite¦calcite. Supergene oxidisation of the orebody extends to a maximum depth of 210m. Isolated deep oxidation occurs along open fracture zones to depths of ~400 metres along æDÆ vein filled fracture zones. Weak supergene copper enrichment occurs in a thin horizon (15 to 60 m thick) that blankets the top of the deposit. The main supergene copper mineral is secondary æsootyÆ chalcocite replacement of sulphide grains and as veins.

Jan 1, 1999

By Kevin O?Callaghan

Applying Legal Concepts - The Crown must consult, and where necessary accommodate, when: - Crown has knowledge, real or constructive, of the potential existence of Aboriginal rights or title and contemplates conduct that might adversely affect it - Duty to consult is triggered at a low threshold - How much consultation necessary? - Proportional to the strength of claim and potential impact - Spectrum: notice to direct involvement in decision making - Not duty to agree or to get consent (no veto) - Reciprocal: Duty requires good faith and sincere engagement on both sides Role of Proponents: Crown may delegate procedural aspects of its legal duty

May 1, 2010

By W. F. Holbrook

THE problem of sulfur control is important in all blast-furnace operations but particularly for certain grades of steel because of the rigorous specifications. During the past decade the tendency has been to produce pig iron, and, hot metal of lower sulfur content. As most of the sulfur in the ion originates in the fuel, the use of high-sulfur coke demands modifications in practice to meet sulfur specifications. While it is generally known that high temperatures and more basic slags favor desulfurization, operators as a rule produce the most acid slag that will permit proper desulfurization. The viscosity of blast-furnace slag has been thought to be related to desulfurization and has been investigated by Feild and Royster1, also McCaffery and his associ-ates2, but apparently no systematic effort has been made to determine the relative desulfurizing powers of slags over the range of composition encountered in practice.

Jan 1, 1936

By C. J. Sullivan

"The outlook for supplying the world's metal needs in the next twenty-five years is good, although in several cases basic costs are likely to increase with rising demand. Metal prices calculated at a constant dollar from 1900 to the present show that for nickel, copper, silver, lead, zinc and tin, prices -and presumably production costs -fell from 1900 to the early 1930s. Since then, they have generally risen, apparently reflecting some depletion in relation to demand. This tendency has been accentuated since the post-World War II adoption of managed, full-employment, growth economics, which have resulted in a sharp escalation in world demand for metals. (Abandonment of such policies, apparently now under consideration in North America, would, of course, affect the pre-dictions of this paper.) Nevertheless, metal prices generally are still below those prevailing in 1900. Exploration potential exists for disseminated ores of many metals still thought of as characteristic of lode and vein deposits. These include uranium, silver, gold, tin and nickel and, to a lesser extent, lead and zinc. Considering the discovery potential for some principal metals in relation to expected demand and prices, I would tend to rate them as follows: molybdenum, zinc, lead, uranium, silver, gold, tin, nickel and copper."

Jan 1, 1970

By John Dodd

Corrosion studies in laboratory ball mills and grinding environment simulations produce corrosion rates and total metal removal rates much lower than those recorded in operating production ball mills. The corrosion component of ball metal loss in commercial mills represents less than 10% of the total loss expressed as micrometers/hour of exposure in recent USBM tests. Such small absolute losses are consistent with ball metal loss measured in production ball mill marked ball wear tests to determine effects of corrosion and abrasion resisting properties of alloys in operating mills which indicate that metal hardness and microstructure determine relative metal loss rates of a given situation. The combination of ore characteristics and grinding process dynamics determine metal loss severity. Alloying for corrosion resistance and modification of the milling corrosion environment yield relatively small metal loss reductions. Alloying and heat treatment to produce high hardness and microstructures of high carbon martensite and for cast irons, M7C3 carbides produces the lowest metal losses in typical wet grinding applications.

Jan 1, 1984

By Garston Blackwell

Abstract - During geostatistical estimation of block grades, the kriging process produces a measure of error, the kriging variance or the kriging standard deviation. Estimation of the block error depends on the semi-variogram model for a deposit, which reflects fundamental characteristics of a deposit such as (1) nugget effect, (2) range of influence of grades, (3) different local spreads of data as a function of average grade (proportional effect), (4) nested structures, and (5) underlying anisotropies in the data; this model may be affected by sampling or assaying limitations, however. Because the kriging error incorporates so many features of both the deposit and data to be used for estimation, it may offer a substantial improvement on block classification over traditional procedures such as data density. Practice indicates that the relative kriging standard deviation (RKSD) is particularly useful for block classification in measured, indicated and inferred categories. Plots of RKSD in plan and section also can be used to demonstrate where extra drilling and sampling would be most advantageous for upgrading the class of some blocks. Moreover, the use of grade and RKSD filters can show where material near cut-off grade is poorly defined, indicating sampling target areas to improve block classification in the vicinity of the ore-waste boundary.

Jan 1, 1998

By A. G. Loomis

METHODS for measuring relative permeability as a valid function of saturation were compared by the. Bureau of Mines, using core samples from representative oil-productive California formations, from the Bartlesville sand in Oklahoma, and from synthetic samples. Measurements for gas-oil systems were made by steady-state dynamic, unsteady-state displacement and two stationary-phase methods. Measurements for water-oil systems were made by the unsteady-state displacement method. As the ratio rather than individual relative permeabilities is measured by the last method, three methods for calculating individual relative permeabilites from their measured ratio were compared for gas-oil systems and two methods for water-oil systems. Errors arising from capillary discontinuities, such as the end effect and stabilized-zone flow, are discussed and evaluated; possible errors rocs arising from turbulant flow are also examined. The inapplicability of non-steady-state methods for water-oil systems that are not definitely oil-wet is discussed in detail. Measurements of relative permeability to both gas and oil can be made quickly and accurately by the steady-state dynamic method when rates of flow of the two phases are sufficient to minimize the capillary discontinuity at the outflow end of the sample. At such rates relative permeability-saturation measurements are essentially independent of the rate of flow. The steady-state method wits modified by a dispersion section at the inflow end of the sample acid designated tie dispersed-feed method.

Jan 1, 1962

By Gabriela Lemos Lages

Os parâmetros influenciadores do processamento mineral para a concentração magnética, como granulometria das partículas, fluxo de alimentação da polpa, susceptibilidade magnética, atuam de forma conjunta em uma planta de beneficiamento. Foram analisadas amostras de polpa contendo sulfetos de níquel, cobre e metais preciosos em seis amostragens objetivando medir a eficiência de um separador magnético de tambor de 750 Gauss em um circuito primário de britagem. O rendimento do equipamento na planta industrial foi comparado com os parâmetros medidos em laboratório. Os resultados obtidos da granulometria médias das partículas da polpa para 80% e material passante (P80) foram: 150 µm, 300 µm, 163,6 µm, 146,1 µm, 287,5 µm e 164,8 µm, e a taxa de alimentação do circuito variou entre 30,2 tph e 55,2 tph, com pressão de lavagem média de 1,0 kg/cm3. As amostras foram submetidas ao balanceamento metalúrgico utilizando o software Bilmat 9.5, após os resultados dos ensaios de caracterização: ICP-metais básicos, Satmagan e LECO-S. O percentual médio de recuperação magnética do laboratório foi de 80,1%, enquanto na planta a média foi de 96,38%, com a eficiência da planta em torno de 20,8% superior à recuperação magnética em laboratório.

Oct 30, 2017

By Pedro Porto Silva Cavalcanti

A suscetibilidade à degradação mecânica de pelotas de minério de ferro é diretamente influenciada tanto pela composição quanto pela sua estrutura. O trabalho analisou criticamente essas relações para pelotas queimadas para a redução direta, por meio de análises detalhadas com quatro tipos distintos de pelotas, que incluíram análises químicas e mineralógicas, medidas de porosidade e distribuição de tamanhos de poros por tomografias de raios X, distribuição de poros por região da pelota por meio de microscopia, da dureza, bem como de resistência à compressão, abrasão, bem como um novo método de avaliação da resistência à fragmentação por abrasão. O trabalho mostra que há, de fato, forte correlação entre a suscetibilidade à degradação e várias dessas características analisadas. Forte correlação foi observada entre a porosidade e o tamanho máximo de poros. Boa correspondência qualitativa foi observada entre o acabamento superficial e a resistência à compressão. Resultados de um novo teste proposto de suscetibilidade à fragmentação superficial sugerem que a porosidade total e a mineralogia exercem pouca influência nesse comportamento, enquanto as características superficiais, como o acabamento e a microdureza exercem uma influência direta nesse mecanismo.

Aug 17, 2017

By L. Sahu, S. Bhattacharya, S. Dey

"An ideal procedure to determine the limits of flotation-based separation, as is the case with washability analysis for density separation, does not exist. Therefore, a procedure called release analysis, considered to be the counterpart of the washability process in density separation, was developed to evaluate the flotation characteristics of coal fines. Since flotation is a complex process it is necessary to know the maximum recoverable yield that could be achieved at a target ash level and what could be obtained by release analysis. Due to a number of limitations in the initial procedures, modifications were recommended by various researchers to generate an optimum separation curve. This paper presents a review of, and a discussion on, the chronological evolution of release analysis methodology over the decades. Notwithstanding the availability of a standardized release analysis procedure, such as BS 7530, the paper highlights the critical parameters involved in the procedures, such as coal type, feed characteristics, choice of reagents and dosage, operator bias, and design features of the flotation cell IntroductionCoal is a heterogeneous substance consisting of various combustible constituents (macerals) and associated mineral matter. The kind and abundance of the various macerals present in the coal, such as vitrinite, semivitrinite, exinite, and inertinite, determine the type of coal. As macerals are formed by biological degradation of different parts of the plant material, they have different properties based on their original composition. Coal cleaning processes are dependent on the differences in physical properties between the coal components (the macerals) and also between the macerals and the mineral matter. Thus the cleaning characteristics of the coal might vary from one type to the next. The cleaning processes influence the distribution and the concentration of macerals in the various size and density fractions of the cleaned product."

Jun 1, 2019

By Sanchita Chakravarty, Sumantra Bhattacharya, Divya Jyoti, A. K. Mukherjee, Soni Jaiswal

"Release analysis is independent of collector and frother dosage and type, but it is primarily influenced by the degree of liberation or “state of release of the sample”. The shape of release curve is an indication of the degree of liberation. This paper briefs about the effect of reagent combination, particle size and surface characteristics on the release analysis of difficult-to-clean LVC coal.Release analysis of three LVC coal fines obtained from two different coalfields of India was carried out at three different size levels such as -0.5mm, (-0.5+0.1) mm, and -0.1mm. The collectors used were n-dodecane and commercial diesel oil. Incomplete liberation of coal fines even at a size of -100µm, corroborated by photomicrographs of ROM and clean coal macerals, in a great measure reduced the flotation-based cleaning potential of the fines. FESEM images of fines reveals that the adherence of ultrafine onto the surface of relatively coarser particles reduced the clean coal recovery. The results obtained also appear to be coal, reagent combination and, particle size and particle surface specific. Only one coal indicated the liberation as is usually expected for -0.1mm particles with a reasonable yield of 65% at 18% ash. INTRODUCTION Froth flotation has a long history of being used to treat coal fines. Coal flotation is considered to be difficult, if the percentage of Near Gravity Material (NGM), i.e. essentially locked particles, in flotation feed is >10% [Aplan, 1993], which is usually the case with all the coking coal fines in India. The fines are rich in vitrinite, so valuable for coking coal. Unfortunately, there appears to be no standard procedures to determine the separation efficiency of froth floatation. Release analysis proposed by C.C. Dell in 1953 [Dell, 1953], aimed to determine the ultimate floatability of coal. Several other techniques had been proposed but release analysis technique has been considered to be a vast improvement over the batch flotation process [Forrest et al. 1994]."

Jan 1, 2018

By H. K. Lin

Deepwater discharges of sulfide flotation tailings have been practiced for several decades. Oxygen penetration and organic matter content in such environments are the two major factors that determine their reduction-oxidation condition and hence the rate of sulfide mineral dissolution under such discharge environments. In this study, the effects of solution redox potential and pH on the dissolution of some heavy metals from sulfide flotation tailings were examined. Zn, Pb and Cu concentrations in solution were all higher at a higher redox potential and lower pH. Dissolved Zn concentrations reached 100 ppm even at a low redox potential of 105 mV and near neutral pH after 33 days. Pb concentrations were below 2 ppm at 105 mV and near neutral pH after 165 days. At 105 mV, the Cu concentrations were below 0.2 ppm at near neutral pH after 165 days. At pH 2.3, the Fe concentrations were higher at 420 mV than at 105 mV. But at pH 6.8, the Fe concentrations were lower at 420 mV than at 105 mV, due to the oxidation of Fe2+ to Fe3+ and the subsequent precipitation of ferric hydroxide. Arsenic concentrations in solution were all less than 0.002 ppm. For Zn, Cu and Fe, no significant differences were observed between the tests in solutions prepared using seawater and those using distilled water. However, Pb concentrations reached higher levels in solutions prepared using seawater.

Jan 1, 2009

By Elaine T. Cullen, Thomas W. Camm

The mentor/learner model is a time-honored approach to teaching, including within the mining industry. Miners know when they see excellence and have a deep respect for experts in their field. By using expert miners as mentors to other, less-experienced miners, training programs can be developed that will have a legitimacy and credibility that resonates with those being trained. Building upon concepts in current theories of adult education, this paper highlights the unique advantages of using mentoring as a teaching method that can make the educational experience both interesting and effective. Current NIOSH safety training materials use these concepts to deliver effective adult learning experiences for workers in the mining industry.

Jan 1, 2002

By R E. Myers, G N. Phillips

Many of the worldÆs larger iron ore deposits are hosted by rock sequences of Archaean to early Proterozoic age. Most models for the genesis of these deposits are influenced, either directly or indirectly, by the nature of the atmosphere at the time of their formation, and more specifically by the presence or absence of oxygen in the early atmosphere. Since the early-1950s, the geological literature suggests that the Archaean atmosphere was æreducingÆ, and that it may not have contained significant amounts of free oxygen until ca 2 Ga. There are many different definitions of the term æreducingÆ, but the criterion adopted here is whether crustal iron was limited to Fe2+, or whether Fe3+ was also widespread, ie was there scope for redox changes in the state of iron? Significantly, major Australian banded iron formations span this period of inferred atmosphere transition, eg Mt Goldsworthy, Mt Tom Price, Middleback Ranges. Geological evidence for a reducing Archaean atmosphere is both ambiguous and controversial (see review by Phillips, Law and Myers, 2001). Many earlier ideas (eg no Archaean redbeds; all very large iron ore deposits being post-Archaean) have been disproved by dating, whereas other evidence (eg homogeneous detrital gold grains, inferred palaeosols) has not withstood geological scrutiny. The interpretation of some data sets (eg inferred detrital uraninite and pyrite in some Archaean meta-sedimentary rocks) is still controversial. In fact, some lines of evidence now suggest that oxygen was present in the atmosphere well before 2.5 Ga (eg sulfates in the Pilbara craton, carbon distribution in clastic sedimentary rocks). An oxidising Archaean atmosphere has important implications for the development of iron formations. First, the atmosphere is an obvious potential source of oxygen to stabilise ferric iron minerals. Second, reduced fluids in equilibrium with ferrous iron are commonly inferred to transport iron in solution to the depositional site. The redox state of the atmosphere thus provides critical constraints on the solution chemistry of surface waters, effective transport paths for iron and particularly on viable precipitation mechanisms. Iron formations developed from fluids in equilibrium with the atmosphere also have the potential to provide important constraints on the evolution of EarthÆs early atmosphere. If an oxygenated atmosphere is a necessary condition for the development of iron formations, then the Archaean atmosphere must have been oxidising since at least 3.5 Ga. If the redox state of the atmosphere is not a necessary condition, then the time distribution of iron formations cannot be used to provide constraints on atmospheric evolution. Given these uncertainties, models for the genesis of iron ore deposits of Archaean or early Proterozoic age should not rely on a reducing atmosphere in the absence of independent evidence and the alternative of an oxidising atmosphere should also be considered.

Jan 1, 2002

The lignite resource in the southern part of the South Island is New ZealandÆs largest source of indigenous primary energy. The ten deposits evaluated by the Liquid Fuels Trust Board (LFTB) have a total recoverable reserve of 6.2 billion tones equivalent to 74 000 PJ of energy or 20 times the original energy content of the Maui gas field. Updating the economics of the original LFTB studies indicates that lignite could be mined for between NZ$1.0 and 3.0/GJ. Its conversion to synthesis gas for production of petroleum products, chemical methanol, ammonia/urea fertiliser or electricity would be in the national benefit and likely to be commercially economic at todayÆs product prices.

Jan 1, 2005

By Peter F. Weiss, H. Riedler, I. M. Moschitz, A. Olsacher, G. B. Fettweis

CONTENTS : 1. NATURAL FACTORS Geology Petrography and Rock Mechanics Mining System Orientation Rock Bolting System Movability of the Ore Grain Size Distribution Permeability Contamination Value of the Ore Hydrology 2. TECHNICAL FACTORS Height Length and Width Drawing Areas Time Factor Water Predrainage Surf ace Draining Underground Draining Advancing Slitting Sequence of Development Initiation of the Caving Process Drawing Rate 3. SPECIFIC MINING RULES Advancing Development Drawing Rate Interruption of Drawing (Water Distribution, Concentration of Mud, Dilution) Blasting 4. CONTROLS Safety Controls for Operation Computerised Drawing Control Structure of the Computer Program Hard Ware Print Outs 5. SUMMARY 6. ACKNOWLEDGEMENTS 7. REFERENCES Under the heading "Development System for Block Caving under Severe Conditions" a report was presented to this congress regarding a magnesite mine using block caving for several years. On account of the experience gathered in this mine and the results of far reaching exchange of experience, as well as under due consideration of the international literature it is tried to systematically list and briefly discuss the following factors that have to be considered for development and draw control of block caving. 1. NATURAL FACTORS It is self evident that this implies all those circumstances given by nature and which cannot be altered by man. Any mining activity is subjected to those and the success is depending on how far technology can be adjusted to those conditions. Geology Deposits of considerable thickness with rather steeply inclined flat-faced contacts are optimal for block caving. While vertically there is practically no limitation- for the deposit, theoretically, the smallest horizontal basis apt for operating block caving is the minimum area necessary to get the rock to completely cave in by undercutting and drawing. Practically, only consider- ably bigger main dimensions are found, mainly because of technical factors (machinery and equipment) and economic factors (cost ratio of exploration vs. development, danger of contamination).

Jan 1, 1981

By J. Wong, M. G. Lipsett, L. K. Daneshmend

"Current trends of increased size, complexity, and automation of surface mining equipment necessitate more comprehensive and objective techniques for equipment comparison and selection. The field of reliability analysis provides tools to generate quantitative bases for maintenance and reliability aspects of such comparisons. Results from statistical analyses of failure and repair time data are used to perform the comparison. A case study is presented which analyzes five machines of two different technologies and three different designs.IntroductionThe surface mining industry is currently faced with a rapid evolution in production equipment. The more obvious trend in this evolution is the steady introduction of even larger machines. Parallel, and complementary, to this increase in size is the introduction or adaptation of new technologies. Together, these two trends result in new surface mining equipment designs; these designs are often more complex and may feature technologies that have yet to be proven for the application or at the scale they are now fielded.The prospect of significant automation of open pit equipment is also bound to add complexity to future equipment designs. Semi-automated features, such as drilling controllers (Aquila, 2000), have already been commercialized. Fully autonomous haul trucks have been demonstrated in open pit mines (Jackson and Zoschke, 2000). Design concepts for comprehensive teleoperation of open pit operations have been formulated (Lipsett, 1998).With this rapid availability and deployment of new technology and equipment, managers and maintainers are faced with a multitude of decisions regarding what equipment to acquire and what maintenance strategies to implement. In light of this evolution in mining equipment, it is necessary to develop better methods for making equipment management decisions (Dessureault et al., 1999; Paraszczak, 1999). The incentive for development of such techniques is that a large portion of an open pit mine’s operating cost is maintenance related, as shown in Table 1."

Jan 1, 2000

"Longwall shearers are widely employed in underground coal mines. The reliability of such machine has significant importance for successful mining operations. This paper aims at studying reliability of a longwall shearer using failure data recorded for a year. Data was pre-processed, sorted and selected for analysis. Selected data is then examined using statistical models. Distribution fitting of time-between-failure (TBF) and time-to-repair (TTR) are accomplished using three different models. Goodness-of-fit criteria is used to ascertain the best fitting model. Reliability in terms of mean-time-between-failure (MTBF), and mean-time-to-repair (MTTR) are calculated using the model which best represents the failure data. Exponential distribution best represents the time between failure and lognormal distribution the time to repair data. A well-known risk management technique Failure Mode Effect and Criticality Analysis is used to evaluate the critical breakdowns. Critical system/parts, experiencing regular failures is delineated based on this analysis. INTRODUCTION Mining is a capital intensive process, and huge monetary investment is required to develop and operate a mining project. Heavy and expensive equipment’s are employed in development and operation of these projects. In order to ensure timely completion of set milestones, it is mandatory that equipment’s perform their required task productively. Delays are not unusual owing to breakdown of these equipment’s. Breakdown or failure experienced by any of the equipment pose heavy financial burden. Moreover, frequent times, companies have to employ and dedicate additional resources to make up for such delays. Delays in project is not only detrimental to company’s image in market, but it also interrupts customer commitments. Mines having history of not fulfilling their promise usually get lower commodity price. Penalties are also imposed on the companies defaulting its obligations. Especially, in today’s world where competition among the companies are growing, success means keeping up the commitments in a timely manner. Heavy machinery and equipment are instrumental in success of any project. These machinery and equipment’s have to reliable in a sense that they can perform the set task in given time period. Reliability of these equipment plays a pivotal role in success of any project. The reliability analysis of mining equipment has long history. Many researchers have applied different statistical models for analyzing the reliability of mining machines (Samanta, Sarkar [1]. Kumar and Klefsjö [2] demonstrated the use of the power law process model for reliability assessments of repairable mining machines. Barabady and Kumar [3] performed the reliability analysis from failure data of the crushing plants."

Jan 1, 2018