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By Caithness SJ, Heape JMT

Following the discovery by CRA of gold at Mt Kare, and the subsequent 1988-90 gold rush, mechanised mining of the alluvial resource is now being carried by a company jointly owned by CRA (51%) and landowners of the area (49%). Mining is currently being carried out using small gravity processing plants fed by hydraulic excavators. Use of hydraulic mining techniques will be limited to over- coming difficulties related to the high clay content of the material and the soft nature of the bedrock. Current resource estimates suggest that the alluvials will have a mining life of three to four years. During this time, exploration of the hydrothermal gold mineralisation at Mt Kare will be carried out by a wholly-owned company of CRA. It is hoped that this will lead to establishment of an economic primary gold resource.

Jan 1, 1991

By Wilson D, Kirkland J

Compressed air energy storage (CAES) uses low cost off-peak energy to compress air and pump it into pressurised underground storage. Expanding the air through a modified form of gas turbine generates electrical energy when required. While generating power, a CAES station consumes approximately one-third of the gas required for the equivalent installed capacity of a conventional gas turbine. Air can be stored in underground rock caverns, caverns in salt domes, or in aquifers. Existing CAES power stations use caverns mined out of salt domes. Aquifer storage for CAES has been proposed, but not yet implemented. The groundwater in the aquifer would be displaced during air injection and when required the air would be extracted using the natural hydro-static pressure. Victoria has no salt domes, but has aquifers onshore in the Gippsland Basin with geological dome structures of suitable depth, discovery pressure, porosity, permeability and caprock for CAES development. Field tests costing several million dollars would be required to prove the suitability. The most suitable aquifer is near Seaspray, where several dome structures exist. The aquifer, comprising of coarse sands capped by coal and mudstone, is some 600 metres deep with a hydrostatic pressure of 6.3 MPa. Computer simulation of injection and extraction of air from the aquifer under various combinations of horizontal and vertical wells, permeability and tubing head pressures indicated the largest aquifer structure had the capacity to sustain a 300 MW station. A well field comprising of 24 directionally driven wells with a horizontal exposure to the aquifer would achieve the air flow rates required. Using plant similar to that recently installed at McIntosh Alabama USA, would mean high capital costs compared to standard gas turbine plant. However, a review of modem gas turbines indicated that they could be easily and economically adaptated to CAES duty. Adapting a 120 MW gas turbine would give 344 MW output. A separate air compression plant would be used. Economic evaluations indicate that, for gas prices above $1.95 per GJ, a 344 MW CAES plant is more economic for intermediate/reserve load duty than simple cycle gas turbines.

Jan 1, 1992

By Y Sha

During the last two decades, China has expanded its iron and steel industry very quickly, from less than 100 Mt/a steel production to over 700 Mt/a. It caused big increases in both domestic iron ore production and imported iron ore quantities year by year. The mode of iron ore supply has changed from almost all domestic supply to major tonnes of imported ore plus domestic ore supply. Over 200 blast furnaces with volumes larger than 1000 m3 each have been built and put into operation. Sinter machines have been enlarged quickly. There are now 135 sinter machines with =200 m2 sintering area each. Pellet production increased from 11.94 Mt in 1999 to 210 Mt in 2011, resulting from rapidly increasing domestic concentrate supply and rapid development of the grate-kiln process. The typical ferrous burden constitution is high basicity sinter plus pellets plus lump. The pellet proportion increased and the sinter proportion decreased gradually. A lot of technical improvements, like deep bed sintering, sintering with a high ratio of limonite, composite sintering, pellet process optimisation, a high ratio of hematite in pelletisation, blast furnace operation with low-grade ferrous burdens and hazardous element control, etc have been made to enhance iron burden quality and to reduce hot metal cost. Chinese iron and steel production is expected to increase slightly in the next few years. Its overcapacity should be controlled effectively. Given the variations of iron ore supply, pellet production will keep progressing in terms of production scale and pellet quality, the sintering process will be improved further by various measures to utilise different ores efficiently, and ferrous burden constitution will be optimised continuously to realise the lowest cost of hot metal production.CITATION:Sha, Y and Wang, Z, 2013. The Chinese iron and steel industry response to the challenges of iron ore supply, in Proceedings Iron Ore 2013 , pp 7-14 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 12, 2013

The fundamental features of the Cable Belt Conveyor are described. It consists of independent wire ropes which take the transmission load, and a special reinforced rubber belt which acts 'only as carrier of material. The first cable belt installation in Scotland is described briefly.A general description of this type of conveyor is followed by details of the rubber belt construction and the method of joining sections of belt. The drive unit, the tensioning arrangements and the power requirements are outlined.Applications of the cable belt conveyor are 'dealt with and its advantages summarized.INTRODUCTIONThe cable belt conveyor, as its name implies is a conveyor composed of steel wire ropes and a rubber belt, in which the ropes serve as transmission members, and the belt merely as a carrier of materials.Over the years it has been the ambition of engineers connected with the belt conveyor industry to develop a conveyor that would use the high tensile strength of wire ropes to transmit the stresses involved in the driving of large capacity belt conveyors. Different lines of approach have been adopted in the United States of America and in Britain. In the United States the method adopted was to introduce a large number of flexible steel cables into the rubber belt itself, in the form of a closely packed layer arranged across the full width of the belt. These small cables are packed in a nylon filled duck envelope which is incorporated in the rubber belt. This is commonly known as the steel corded conveyor belt. In Britain, a Scottish firm developed a rubber belt conveyor in which full advantage was taken of the high tensile features of wire rope, without embodying or moulding the wire rope into the rubber belt, so that the two wire ropes and the rubber...

Jan 1, 1957

A study of the electrolysis of PbS in molten PbCl2 showed cathode efficiencies which increased with current density at fixed sulphide concentrations, and decreased with increasing sulphide concentration at fixed current densities. The anodically produced sulphur dissolved rapidly in the melt, the rate increasing with temperature and sulphide concentration. Experiments with diaphragm cells, made to determine the relative effects that dissolution of lead and sulphur have on the cathodic current efficiency, demonstrated that dissolution of sulphur was the major contributor to the lowering in efficiency.

Jan 1, 1973

By Hirst H, McAfee J

In December, 1934, Mr. R. Sussex extruded some silver lead alloy wires in order to determine their electrical resistance. After the determinations had been made each wire was threaded through a sheet of paper on which the composition was noted. The wires were placed in a more or less tangled mass in a cupboard in March, 1935. It was not until September, 1936, that they were re-examined, and it was found that during the eighteen months some of the wires had corroded very badly. It was not until March, 1938, that the wires and the corrosion product could be examined, and the results are given in the following pages. It is of interest to note that none of the numerous silver-lead alloys which have been used for creep testing in the rolled condition have shown a similarphenomenon. The silver content of the rolled alloys was, however, never greater than 0·1%.GENERAL APPEARANCE OF THE CORRODED WIRESThe wires contained 0·1% up to 28% of silver, and a general examination showed that the corrosion had progressed farther the higher the silver content. This can be seen in Fig. 1, which is a photograph taken in March, 1938, of typical wires at a 'magnification of five diameters. In the early stages the corrosive action seems to be localized and an area of grey, yellow or reddish brown powder appears. The grey corrosion product is by far the one, most frequently seen, and in the later stages the only one visible from the outside. The reddish coloured product is sometimes seen on the residual metallic centre when the grey product has been broken away.The irregular extent of the corrosion can be seen in Fig. 2, which shows (natural size) the 5% silver wire after standing two years. The corroded parts are seen to be much thicker than the slightly corroded ones. The corrosion product, being non-metallic, is quite brittle and falls away from the wire on bending. In the extreme case the' whole wire has corroded and presents a cracked appearance as seen in Fig. 1 (281% silver).An approximate idea of the extent of corrosion can be obtained by measuring the diameter of the corroded part. The original diameter in each case was ·050/ ·051 inches and in Table I are given the diameters of the corroded parts after Hand 3 years respectively. When the diameter...

Jan 1, 1941

At Copper Refineries Pty. Ltd., Townsville, two reverberatory furnaces of 420 tonnes capacity are used to melt 210000 tonnes/year of copper for subsequent anode casting. When the refinery commenced production in1959, these furnaces were of 300 tonnes capacity. The original furnaces featured a silica brick hearth, magnesite and chrome magnesite side 'walls, and a sprung silica brick roof, but were unsatisfactory because of thelow refractory life and high costs. With continuous expansion in production and the incentive to increase furnace life and capacity the design of these furnaces has changed greatly since that time.The present furnaces feature all basic brick, a flat suspended basic brick roof, very extensive use of watercooled copper sections, and are of substantially increased (420 tonnes) capacity. Particular attention has been concentrated on high wear areas such as the taphole, side walls, and charging door jambs. Each furnace in its 24 h cycle, is charged, the copper melted, impurities skimmed off, metal "poled" prior to casting, and cast.The service condition during each of these operations is important in considering furnace refractory life.The improvements in operating practices and furnace 'construction which enabled the capacity of the furnaces to be increased are discussed. The life between major repairs to side walls has increased from 90 charges to300 charges.The scope for future improvement is considered and areas for development are suggested.

Jan 1, 1977

By P W. Wypych

The iron ore industry faces significant challenges in the control of dust to meet emissions regulations and goals, as well as ensuring sustainable operations. This paper describes some of the different techniques and innovative technologies that are being developed and implemented to improve the suppression of airborne dust, specifically through the use of high energy micromist sprays. The utilisation of computational fluid dynamics (CFD) modelling and simulation is identified and described as a key enabling technology for an improvement in dust suppression solutions both from a level of understanding the source and flow of dust emissions, and for the development of new systems that can be used in the iron ore industry. CFD modelling is shown to be effective for modelling both spray dispersion and cross-wind effects, allowing designers to develop high-efficiency dust suppression systems with a greatly improved level of confidence when compared to traditional techniques. New high energy micromist technology is also outlined as a key element in developing high-efficiency dust suppression systems. Experimental results and industry applications are presented to demonstrate the significant improvements that can be achieved in suppressing or reducing airborne dust emissions.CITATION:Roberts, J M and Wypych, P W, 2017. Research into improving the efficiency of water spraying airborne dust control techniques in the iron ore industry, in Proceedings Iron Ore 2017, pp 359–364 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

The Central Andes in Peru, Chile, Bolivia, and Argentina , contain two contiguous terranes which were accreted to Gondwanaland between the end of the Devonian and the end of the Triassic. These terranes, Arequipa in the north, and Chilenia in the south, differ from each other in the timing and style of their metallogenic development. However, they contain over 90% of the Central Andean porphyry copper resource. The copper porphyries in the Arequipa terrane are Paleocene to lower Oligocene in age, whereas the Chilenia deposits are mid-upper Cretaceous and mid-upper Miocene. Porphyry copper deposits occur outside these terranes, but are all Miocene in age. Miocene porphyry-style mineralisation also exists in the Arequipa terrane, but is copper-deficient and gold-rich. The accreted terranes may have favoured porphyry and other styles of copper mineralisation because they possessed relatively thin continental crust compared to adjacent parts of the Andes. Crustal thickening which commenced at about 30 Ma in the Arequipa terrane coincided with a major change to polymetallic, precious metal mineralisation which commonly displays high sulfidation characteristics.

Jan 1, 1995

By A Hanna

Quarries around Auckland have reached or are reaching the ends of their lives, which raises issues about rehabilitation. Significant volumes of 'cleanfill' are generated by the City, particularly during phases of urban renewal and development. Emplacement of the fill in quarries removes the problem of fill disposal and provides an opportunity for restoration of the quarry site.There is a compatibility between quarrying and cleanfilling because at quarries:Truck routes are already established Neighbours are accustomed to the effects and appropriate buffer distances have been established Bringing fill into a site attracts aggregate sales and is very efficient. Fill originates from construction sites and ad-hoc excavations and therefore it is not surprising that sampling has shown the quality to be variable. Both Winstone and the Auckland Regional Council have surveyed undisturbed soils in the region to attempt to determine natural background levels of common contaminant substances. Comparison of these levels with delivered fill shows that a high proportion of delivered materials can be regarded as mildly contaminated. Therefore the term 'cleanfill' is, in the Auckland region at least, a misnomer and the term 'managed fill' has been adopted.Historically and presently the only control on quality of 'cleanfill' has been some visual inspection. This leaves the fill operator open to potential liability for creating a contaminated site. Implementation of controls at WinstoneÆs operations has progressed slowly, over some ten years. This is mainly due to the perception that mobility of contaminants within and out of the landfill will be very limited because of the near-neutral pH and abundance of clay minerals in the fill. The methods of control and results of environmental risk assessments at WinstoneÆs Puketutu Island Quarry will be briefly described.

Jan 1, 2002

Standard petrographic profiles for many Permian seams from New South Wales and Queensland have been drawn up. The standard profiles of seams of the same age and from one or more coalfields were used to compile an idealized or type seam sequence for those coals in which more than half the seam profiles were similar to one another. A marked similarity existed between at least 7 of the 10 type seam sequences formed.The configurations of the vitrite-plus-clarite contents of the plies of 95 per cent of the seams could be formed from different arrangements of 3 basic sequences. These were...

Jan 1, 1970

Fines and unnecessarily small rock fragments are created by as many as four identifiable breakage mechanisms which operate close to the charged section or sections of the blasthole. The peak blasthole pressure (Pb) should not exceed that value at which the rock starts to fail in compression. Excessive Pb values can be prevented by carefully selecting:1. the composition, density and/or diameter of the charge, and2. the initiation/priming system.The percentage of fines increases with:1. increases in the charge diameter:blasthole diameter ratio, burden distance, blasthole diameter, effective sub-drilling and size of blast, and2. decreases in blasthole spacing, stemming height and the length:width ratio of the blast block.Decked charges tend to reduce the percentage of fines.Excessive fragmentation is more evident in buffer blasting and sinking cut shots than in blasts fired to a clean free face. Initiation sequences which give effective burdens considerably less than drilled burdens encourage the minimization of fines, as does an inter-row delay time which promotes good progressive relief of burden.The wastage of explosive energy in creating fines is most pronounced where fully-coupled, energetic charges are fired in weak and/or highly porous rocks. This is especially so where forward movement of the strata is impeded by buffer rock, excessive burden distances and/or inadequate inter-row delay times.

Jan 1, 1979

Following extensive trials on a 100 000 tpa Research and Development facility at Kwinana, Western Australia, Hismelt Corporation (wholly owned by Rio Tinto) are confident of the future commercial success of this technology. The Hlsmelt process uses iron ore fines and non-coking coals to produce molten pig iron suitable for feeding to BOF and EAF steelmaking vessels. The unique process configuration combines direct injection of raw materials into the molten iron bath, high rates of metal and slag mixing, and effective post-combustion of the bath gases to achieve efficient coal utilisation. This is the key to the strong economic performance of the process.

Jan 1, 1999

Laboratory flotation tests on sized fractions of a certain number of selected minerals with homologous fatty acid derivatives (i.e. sodium salts and amine acetates) confirm that the higher homologues are more efficient collectors than the lower. Tests were carried out on sized material and finer size fractions floated at lower collector concentrations.It is suggested that selective flotation is best achieved with the reagent which most readily floats the most friable mineral in the ore, and that grade of product will be improved with the lowest usable homologue.INTRODUCTIONFlotation of non-sulphide minerals with fatty acids as collectors is usually less selective than the flotation of sulphide minerals with xanthate collectors. It is common to use the gradation in collecting power of homologous series of xanthates, as well as the more specific effects of activators and depressants, to achieve the separation of sulphides.The original aim of the work was to ascertain whether sodium salts of fatty acids (anionic) and fatty amine aceta:tes (cationic) could be selected from a homologous series to achieve better selectivity in separation of nonsulphide minerals by flotation. Subsequently the importance of friability of minerals in selective flotation was observed and the aim was expanded to develop a more practical approach to the testing of ore.MATERIALS USEDMineralsA series of massive mineral specimens, as pure as could be obtained, was procured. The specimens were cleaned by removing extraneous material, and then crushed and dry...

Jan 1, 1965

By Wylie A. W, Mathew PJ

Bulk density and grade were determined on a variety of ore samples from the Mount Tom Price iron ore mine and the interrelationship between these properties and porosity deduced.Variable porosity is responsible for the wide scatter of data points and low accuracy of prediction in the grade of a single sample from grade/bulk density relationships.However, with a sufficient number of such data points, as from a nuclear geophysical borehole logging operation, the mean ore grade in an exploration-type drill hole (~63 per cent Fe) could be determined by regressionanal~sis with 95 per cent confidence intervals of approximately ± 1 per cent Fe. From the same logging operation, utilizing core data for calibration of the probe, the -mean fractional porosity for the drill hole (0·19 ± 0·016 at 95 per cent confidence interval) was deduced. This is less accurate than the corresponding result obtained on core material in the laboratory (0·20 ± 0·005).The range of porosity was from 0·08 for dense, high grade sectIOns of the ore, to 0·28 for friable ore of high grade or goethitic ore of lower grade. Shale band porosity ranged from 0·15 to anomalously high values of 0·48 believed to be caused by leaching of iron minerals from the shale. Porosity values for the iron ore component of the deposit are comparable to those found for the Cockatoo Island (W.A.) mine, and for sections of the Krivoy Rog (Ukraine) iron ore deposit of the Soviet Union.

Jan 1, 1978

It has long been recognised that Australia can benefit substantially in an economic sense from its rich resource base. The significant resources of the Gippsland Basin are a good example of the wealth of this nation. As cited in popular debate, Australia must value-add to its natural resources to ensure its long term economic prosperity. The significant oil, gas and coal resources of the Gippsland Basin have provided the Strategic Research Foundation with the basis for two major research and development initiatives ensuring the long term economic development of the Basin and Australia. The gas and coal reserves of the Basin together with the area's extensive history in electricity generation provide the rationale for establishing Ceramic Fuel Cells Ltd. A consortium comprising Australia's leading industrialist - BHP, State energy authorities and the Nation's major research and development organisations, has formed Ceramic Fuel Cells to undertake and manage research, development and commercialisation of solid oxide (ceramic) fuel cells which convert fossil fuels directly to electricity with greater efficiency and less pollution than existing technologies. The oil and gas resources of the Basin together with the valuable experience of the operators in recovering these resources, have provided the impetus to investigate the feasibility of a Marine Engineering Research Centre. The commercially oriented research, education and training objectives of the Centre are well supported by the leading industrialists in related industries.

Jan 1, 1992

By K Prendergast, P Dale, I Taylor, A J. Vigar, B Lueck

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. The Kainantu Project is located within the New Guinea Thrust Belt in northern Papua New Guinea. The area has a long history of exploration and production, with the discovery of alluvial gold in 1928 followed by the discovery of vein deposits of gold and copper at Kora in the 1950s and the current Irumafimpa vein gold mine. Current resources on the Kora-Irumafimpa Vein System (KIVS) stand at 1.5 Moz Au, 5 Moz Ag and 217 Mlb Cu.Mineralisation in the region includes gold, silver and copper associated with mid-Miocene age mafic to felsic intrusions. The KIVS occupies a broad north-west-trending mineralised zone more than 2.5 km long and 200 m wide, with the Kora, Eutompi and Irumafimpa veins on the western side and the Judd and Upper Kora veins on the eastern side. Economic mineralisation occurs in two closely related events occupying the same strongly structurally controlled shearing (quartz-Au-telluride veins and sulfide Au-Cu-Ag veins with free Au) and is best described as a significant intrusion-related event with both epithermal and mesothermal facets that does not appear directly related to known porphyry Cu-Au systems as seen at the surface. Significant wolframite is associated with vein quartz of a slightly older age but also occupies the same shear system.The KIVS occurs within a larger mineralised area of approximately 5 × 5 km. It has complex multiphase intrusions, breccias and diatremes that are only partly delineated by drilling and comprises multiple occurrences of Au-bearing veins and porphyry Cu-Au mineralisation. The area is considered to have high potential for extending the current resources and is being actively explored. The proposed recommencement of mining activities recognises the complexity of the KIVS and later disruptive faulting and will require tighter grade control systems, targeted mining techniques and a gravity circuit to maximise free Au recovery.CITATION:Vigar, A J, Lueck, B, Taylor, I, Prendergast, K and Dale, P, 2015. Kainantu gold-copper system, Papua New Guinea, in Proceedings PACRIM 2015 Congress, pp 601–606 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

Rio Tinto has embarked on a journey to use automation to improve the performance of its surface mines. The driver for automation is to improve the accuracy and consistency of mining processes and less to do with cost savings through labour reduction. A key task in most surface mines is blasthole drilling. The degree to how well this is done cascades through the downstream mining process. It impacts scheduling, excavation, slope stability, material handling, beneficiation and final product blending. Improved blasthole drilling was identified as an objective that has a significant business case in most of Rio Tinto's surface mines. This paper describes Rio Tinto's drill enhancement project that has developed a robust system for automating most of the functions on a Terex SKSS16 drill rig. Automated drilling is currently being used in production at the West Angelas iron ore mine in the Pilbara region of Western Australia. A description of the essential elements of the drill automation system is given together with an overview of how automated drilling is performed remotely from the mine office. A review of some of the benefits of the enhanced drill system is given together with the future plans to extend the functionality of the automated drill and the expected benefits.

May 1, 2010

By P Williams, S Flynn, R Birchfield, R Simcock, R Toft, P Comeskey

Direct transfer, or community translocation, comprises salvage and replacement of intact æsodsÆ of vegetation together with underlying soil. It has been applied to New Zealand mine sites restoration of native grasslands, wetlands, scrub lands, and forest. It is an equivalent technique to æinstant lawn or tree gardenÆ, commonly used in urban landscaping. Two to six m2 scoops of vegetation, with up to 0.7 m of soil attached, and including root plates of trees and shrubs, are relocated from stripped areas ahead of mining to sites prepared for restoration. Direct transfer uses hydraulic excavators or face shovels and dump trucks, possibly with the aid of bulldozers and other earthmoving machinery. The main advantages of direct transfer, compared with sowing or planting systems for mine site restoration, are the recycling of plant and soil materials which were often wasted by burying under overburden materials, a significantly faster revegetation process, and restoration of the whole ecosystem (plants, animals, birds, invertebrates, and microbes). The main disadvantages are higher costs of stripping and dumping, a greater degree of machine operator skill required, and scheduling becomes critically important. To illustrate the key principles, this paper gives examples of successes and failures of the technique for a variety of New Zealand mining situations. Direct transfer has been successful for a range of communities, from fern wetland and sub-alpine tussock grasslands to 5 m-tall beech forest under storey and seral shrub land, and from temperate to sub-alpine climates. Successful examples show both rapid recovery of indigenous vegetative cover and conservation of habitat for birds and invertebrates. Failures have resulted from excessive death of plants because of inadequate soil salvage depths, acidic leachates, inappropriate handling of stripped sods by inexperienced machinery operators, or prolonged drought conditions immediately following relocation. Change in plant species composition has occurred where clumps of vegetation are too far apart, or shifted plants were too small - in both cases invasive weeds have smothered the original vegetation. Changes in hydrology can also have significant impacts. Our experience indicates that the advantages of direct transfer far outweigh the disadvantages and is now used as the preferred restoration method, where practicable, at mines where it has been trialled.

Jan 1, 2000

The Estonia Mine, operated by Eesti Energia Kaevandused AS (EEK), the mining division of the Estonian Government's energy company, Eesti Energia AS, is a large room and pillar mine located in Eastern Estonia. It supplied approximately 4.9 Mt/a of oil shale in financial year ending 2010, which is used for electricity and shale oil generation. Due to the Estonian climate and the power station's need for a dry product, Estonia Mine has developed a planning system where short-term demands of the power stations dictate the schedule. Such an arrangement requires maximising flexibility and consequently the mine only operated for 199 days in 2010.The footprint plays a key role in achieving mass mining rates as the 12 km + 12 km lease area allows the mine to split into mining districts that act independently of each other and maximise the number of work areas available. Coupled with this, the geology of the mine is relatively homogenous over the mining lease, simplifying the mine design and production methods.During the last five years, EEK has commissioned a comprehensive conveyor network. Consequently, material handling only requires loaders to dump oil shale direct from the production face onto a chain conveyor that feeds the conveyor network that ultimately supplies the enrichment plant. Dewatering is also of critical importance, with 90 Mm3 of water discharged annually. EEK uses large trenches up to 3.5 m deep and 1.2 m wide to channel groundwater. Track mounted mechanical saws are used to cut slots in the floor, to control overbreak in blasting these trenches.EEK has introduced Salzgitter Machinenbau GB 280S auger drills that drill three 280 mm diameter holes simultaneously. This has improved void hole drilling times and reduced the drilling required for each face, reducing the overall production cycle time. Blasting activities have also been decoupled from other mining activities negating the need for firing times through the use of small independent firings, required to control vibrations.

Dec 6, 2010