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The last two years have seen a rapid change-over from mechanised cut and fill. stoping to the more economic and productive long hole open stoping method, such that today more than 80 per cent of total production is won from open stopes. At first drilling was by sub-level rings and/or parallel up and down holes from inter- mediate sill horizons using conventional exten- sion rod equipment. Sub-levels were developed no more than 40 metres apart to allow accurate drilling. Compact, crawler mounted in-the-hole hammer equipment was introduced as soon as it became available in Australia. Today, all open stope drilling is done with three Atlas Copco ROC306 rigs and two Ingersoll-Rand CMM jumbos. Fans of 115 mm diameter holes, varying from near vertical down holes to horizontal, are drilled with a burden of 3 m. Toe spacing varies from 3.5 m to 4 m. An Atlas Copco DG418 booster compressor is used to boost run-of-mine air from 700 kPa to 1400 kPa in the areas of longest drilling. This has improved overall drilling performance in these areas by 40 percent.

Jan 1, 1977

By Colwell JB, Cronan DS

Manganese nodules cover great areas of deep ocean floor far from land, and have long been considered a major potential resource of nickel, copper, cobalt and perhaps manganese. A decade ago there was a period of intense evaluation of nodule fields, especially those lying between the Clarion and Clipperton Fracture Zones in international waters southeast of Hawaii. There, nodules are abundant and of high grade (average of 2.4% Ni+Cu+Co). The evaluation activity has since declined, but a recent agreement on lease boundaries among all interested parties may lead to a resurgence of work. Indeed, French and Japanese groups have pushed ahead with field and economic assessments.The Southwest Pacific, where there are large nodule fields in the waters of the Cook Islands and Kiribati, has seen considerable assessment of resources in the last ten years, especially through a major field programme of the Japanese Metal Mining Agency. The best prospect appears to be in the South Penrhyn Basin, in Cook Islands waters, where nodules are very abundant but of only moderate grade (1% Ni+Cu+Co). Using a cut-off of 5 kg of wet nodules per m2, Cronan (1989) and Cronan et al. (1989) have estimated the total resource to be a huge 110 million tonnes of Ni+Cu+Co.

Jan 1, 1990

By A Fareth

Constructed between 1885 and 1891, the New Croton Aqueduct (NCA) in New York State is a 50 km long (31 mi) brick-lined tunnel conveying water from the Croton watershed north of New York City to distribution systems in the Bronx and Manhattan. Except at two siphons, the aqueduct operates as an open channel conduit from the New Croton Reservoir downstream 39 km (25 mi) to the Jerome Park Reservoir in the Bronx. The remaining 11 km (6 mi) is operated as a pressurised conduit and includes a major siphon, of circular cross-section, under the Harlem River. The aqueduct has a flow capacity of approximately 1100 million litres of water per day (13 m3/s or 290 million gallons per day) and supplies on average ten per cent of New York CityÆs drinking water. The CityÆs water supply system is operated and maintained by the New York City Department of Environmental Protection (NYCDEP). This paper covers the work done during the three main stages of the program to rehabilitate the entire NCA: inspections, design and rehabilitation. It also includes some of the more interesting structural findings of the original construction as well as documents and drawings from the NYCDEP archives. The rehabilitation program has been underway in phases since 1993, with inspections scheduled to minimise outages, allowing this strategic aqueduct to remain in service during critical seasonal periods. The open channel flow section of the aqueduct in the north is horseshoe shaped, with inside dimensions of 4.1 m (13.6 ft) in width and 4 m (13.5 ft) in height. The pressurised section is 3.7 m (12.3 ft) in diameter, and includes a 90 m (330 ft) deep siphon under the Harlem River. A total of 163 million bricks were used in the construction, enough to build a 48 km (30 mi) wall around Manhattan Island, 3 m (10 ft) thick and 15 m (50 ft) high.Between 1993 and 1997 a series of in-tunnel investigations were performed in the open channel portion of the NCA, consisting of field inspection, non-destructive geophysical testing, and coring of the brick liner. Between November 2004 and September 2005, a major inspection program was conducted to assess the condition of the 11 km (6 mi) long pressurised section and all shafts, headhouses and blow-off structures along the entire 50 km (31 mi) alignment. Inspection methods included using an underwater remote operated vehicle (ROV) equipped with sonar and cameras to inspect the deep siphon, fibre optics examinations of probe holes drilled through and beyond the brick lining, and core holes and geophysical inspections to assess properties of the liner and behind-the-liner materials. A water pressure and test grouting program was conducted to assess methods and expected grout takes for the rehabilitation work in the pressurised sections. The rehabilitation program is anticipated to be completed in 2010.

Jan 1, 2008

Many block caving operations experience difficulties during undercutting, resulting in draw horizon damage, production loss and extensive drift repairs for the life of the block cave. This paper deals specifically with block cave undercut aims strategies, methodologies and management to avoid the problems indicated above.

Jan 1, 2000

The Nagambie heap leach gold mine commenced production of gold in September, 1989. The mine,120km north of Melbourne in Victoria, Australia, was developed by Perseverance Mining Cor- poration Ltd, a junior Australian mining company, with no other operating mines. Gold production to December 31, 1990 was 47,621 oz. The mine is now producing at the rate of about 45,000 oz per year. As of February 28, 1991, resources at the mine are 5.1 million tonnes measured, at 0.65g/t Au while reserves were 1.65 million tonnes at 0.86g/t Au of proven, heap leach ore, plus 0.37 million tonnes at 0.40g/t Au, of dump leach ore. Metallurgical recoveries expected are 80 per cent for the heap ore and 60 per cent for the dump ore. Perseverance Mining Corporation was listed on the Australian Stock Exchange on April 2, 1987, after a capital raising in March that year. At this time the company's issued capital was 4 million ordinary 25ó shares, 3 million of which were issued to the public to raise $0.75 million.

Jan 1, 1991

The applicability of Bieniawski and Hoek-Brown empirical strength criteria has been assessed for different groups of coal and various types of intact rocks by using a vast number of published triaxial test data from various places. Analysis of individual data sets revealed that the traditional forms of the criteria do not have a perfect agreement with the data. A strong negative correlation has been observed between B in Bieniawski's criterion and m in Hoek and Brown's criterion with uniaxial compressive strength of materials. Both criteria have been modified and empirical relationships have been introduced for coal as follows:m = 62.903 - 34.213 (log pc) 0.9772B = 10.152 - 4.709 (log pc )0.8889Similar relationships have been developed for different rock types as well.A comparison between the applicability of each of the above approaches with the conventional criteria reveals a very significant advantage for new approaches and a supremacy for the Bieniawski criterion in all cases particularly in the case of coal.The modified Bieniawski criterion fits coal as well as different types of rocks with excellent accuracy.The modified Hoek-Brown criterion gives a good result for rocks but does not fit coal data quite well. In other words, Hoek-Brown criterion is not an suitable one for coal.

Jan 1, 1998

The grade (or value) to volume relationship which constitutes a target orebody is used to show that the concentration of diamonds in an economic deposit may be as low as O.Olg/t. Diamond valuations from an Indonesian deposit demonstrate that the largest 5% of the diamonds in the deposit contributed 25% of the mass of diamonds recovered and 70% of the value from the ore. The need to consider the large stone content and the probability of recovery is used to estimate that the sampling density is required to be as high as 4-10,000ppm for a VLC deposit. This is compared with an acceptable sampling density for a bauxite deposit of 700ppb. A case history of the discovery of a diamond bearing paleo-channel in the Ellendale field in Western Australia illustrates that the sampling task becomes impractical. It requires an excavation in excess of 300,000 bcm of material to prove a 5M hem ore reserve. The conclusion is reached that setting up a small scale mining operation is an appropriate method of proving such an ore reserve and that the Code of Reporting should allow a category of "Mineable Resource" to cover such a situation.

Jan 1, 1990

By R Shrimali, P Rajmeny, L Shekhawat, A Joshi

Rampura Agucha open pit mine has successfully been excavated to a depth of 320 m, incorporating multistage working. The key to success is the implementation of presplitting as control blast measures at every stage of mining, including intermediate cut backs, in addition to the final wall. The major challenges encountered in establishing presplitting in the hang wall as compared to the footwall of the mine are:reversely dipping foliation, ie dipping into the hang wall itselfstriking obliquely at an angle of 20–30° with regards to the general strike of the pit wallthe presence of numerous geological planes of weaknesses like major faults, slips, etc.Control blast parameters like hole inclination, spacing and stand-off with buffer row were chosen initially from the literature survey and were subsequently fine-tuned by field trials to the mine geo-mining conditions of the hang wall. Electronic initiation used for trim blasts along with double presplitting in fault-affected zones helped in getting better presplit performance and resultant stability of the hang wall.CITATION:Rajmeny, P, Shrimali, R, Shekhawat, L and Joshi, A, 2015. Establishing the design parameters of a control blast for long-term stability of the hang wall at Rampura Agucha Mine, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 437–446 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

Vatukoula is a gold mining township situated at the south-west periphery of a Tertiary caldera which measures 3 miles by 4 miles. Erosion of the caldera resulted in the formation of a topographic depression, called the Tavua basin, covering about 30 square miles. This area, also known as the Tavua Goldfield, has been the site for spasmodic prospecting since the initial discovery of gold in 1932.The mineralization at Vatukoula is typically epithermal with the gold occurring as tellurides, auriferous sulphides, and to a much less extent as native gold. The lodes are confined to three major structures i.e. north-west shears, flatly dipping structures (flat makes), and local shatter orebodies.Within these structures, at least five types of controls are recognized to account for the localization of the oreshoots. The dominant control is structure.The lode structures are related to the overall structural pattern of the Tavua basin. This pattern, which is controlled by the collapse planes of the caldera and a north-west shear system, produced a "shatter block" atVatukoula and elsewhere around the caldera.Structural analysis indicates there are certain areas in the Tavua basin where exploration could be rewarded by the discovery of orebodies with similar controls to those of the productive Vatukoula block.

Jan 1, 1967

By Hendrix JL, Nelson JH

Three ores (sulfidic, oxidized and carbonaceous) were analyzed to determine the effects of leaching time, ore depth, and ore mineralogy on cyanide species concentration. NaCN solutions were percolated through opaque columns filled with milled ore. Column design made liquid sample collection possible from various depths at specific times. The concentrations of weak acid dissociable(WAD) and total cyanide, Fe(CN)63 , Fe(CN)64 , SCN , and Cu(CN)43 were determined for each sample. Extended percolation time led to increases in WAD cyanide concentra- tions and decreased SCN and Cu(CN)43 concentrations regardless of ore depth. WAD cyanide concentration decreased while Fe(CN)64 concentra- tion increased with ore depth. Highest concentrations of Fe(CN)64- SCN and Cu(CN)43 were found in the sulfidic ore, with expected low WAD cyanide concentrations. Lowest concentrations of Fe(CN)64 , SCN 3 and Cu(CN)4 were found in the oxidized ore. Intermediate concentra

Jan 1, 1988

By L L. Kuhar

The AMIRA International P843A Geometallurgical Mapping and Mine Modelling (GeMIII) project is an interdisciplinary research collaboration between 17 global mineral companies and four research organisations aimed at providing support for the emerging industry trend of geometallurgy. The main aim of the project is to develop predictive geometallurgical indices which can be incorporated into a resource block model to maximise the commercial value of an orebody and to minimise the social and environmental impact of mining operations.Researchers at the Parker Centre/CSIRO have been focusing on the development of predictive hydrometallurgical indices for the GeMIII project via rapid, small-scale, cost-effective tests and protocols for comparative ranking of attributes relevant to leach performance. The focus of the small-scale leach tests has been to determine the leach index (relative indication of leach performance), recovery, impurity deportment, reagent consumption, effect of size/degree of liberation and mineralogy of samples for their relative ranking. Predictive tests for heap leach hydrology (related to agglomerate characteristics) and slurry rheological behaviour are also being developed.

Sep 5, 2011

By Shinnosuke U, Zhang HE, Qian X

In this paper it is recommended that pyrite is to be separated as froth from arsenopyrite by selective depression of arsenopyrite in strong alkaline medium (1), by oxidation with chlorinated lime (II), by co-use of chlorinated lime with sodium carbonate (III), and by modification with `L' reagent (know-how) without filtering to get rid of residual copper ions after Cu activation (IV). The corresponding principles of these (new) effective methods were briefly discussed. The artificial mixture (1:1) of pyrite and arsenopyrite could be successfully separated, and concentrates of pyrite containing 2.12 per cent (I), 7.00 per cent (II), 2.60 per cent (III) and 3.16 per cent (IV) arsenic with recovery of 90.9 per cent (1), 89.5 per cent (II), 89.0 per cent (III) and 81.4 per cent (IV) respectively can be obtained by only one flotation. Some effective precautions were suggested to improve the separation of arsenopyrite and pyrite (or other sulphides) by flotation.

Jan 1, 1993

In order that the processes seen may be followed in their proper 'order, the subject will be dealt with as follows, (1) Wallaroo and Moonta Mines; (2) Wallaroo and Moonta Mines Smelting Works; (3) Broken Hill Mines; (4) Concentration at Broken Hill; (5) Smelting and refining of Lead, Silver, and Gold at Port Pirie. The first acquaintance with the copper region was made at the Yelta shaft and dressing mill of the Parramatta Copper Mines Co. at Moonta. The country rock at Moonta is a hard, tough, felsitic porphyry, the copper lodes having a general strike of N. 30° Kilipping from 500 to 70°. This necessitates shaft-sinking on the lode, and underlay shafts are the rule on the field. The ore is raised in the Yelta shaft in wheeled skips, and consists of ·chalcopyrite, bornite, pseudomorphic hematite, containing, in addition, molybdenite and tourmaline. The ore from the bins at the brace is passed over a grizzly; the over-size is hand-picked into smelting ore, concentrating ore, and waste rock (00 attle ), which is sent below for filling. The under-size is elevated to a trommel having in. holes. The over-size falls on to a picking belt made up of lengths of rope strapped with iron, working over wooden pulleys.

Jan 1, 1907

WINDING engines are one of the most important units in the equipment of a mine. Upon the winding machinery depends not only the output of the mine, but it supplies in most cases the only means by which workmen enter and return from the mine, and consequently the utmost care and attention is desirable in its design. The efficiency of a direct acting winding engine, as a machine is very low. In other words, the proportion between the useful work performed and the actual work the engine is capable of performing (under the most favourable conditions) is very small. The reasons for this are:-1. The intermittent nature of the work; the engine is stopped from 20 to 25 %(or even more) of the time which would constitute a useful day's work.2. The large amount of power that is absorbed applying the brakes to bring the load to rest.3. That the net useful load raised is small in comparison with dead load to be lifted, and the parts to be set in motion.4. That, owing to the frequent stops, initial condensation in the cylinders is always greater than in a continuously running engine, whilst radiation from steam pipes, valve chests, &c., goes on whether the engine is running or...

Jan 1, 1911

By Readett D. J

Soluble salts can be removed from Bowmans lignite by water and acid leaching. The success of the removal of water soluble or acid exchangeable impurities is directly associated with the efficiency of dewatering these slurries. The filtration characteristics of a slurry at its natural pH (4.0) were poor, with a filter cake moisture of 65%. Acid treatment of the slurry at pH2 caused the filter cake moisture content to drop to 61 %. Various oils, oily surfactants and a flocculant were tested to determine the conditions for minimum filter cake moisture. A series of pilot scale filtration tests were conducted on flocculant dosed slurries with and without washing on a horizontal test unit. Moisture contents of 54% were obtained in laboratory testing using high additions of oily surfactant. For the pilot scale test work, moisture levels close to 60% were obtained with low flocculant additions, similar to results obtained in laboratory studies. Removal of soluble salts could be correlated directly to the final moisture content of the filter cake. This process of leaching followed by filtration resulted in the removal of approximately 75% (more than 80% with washing on the cloth) of the sodium chloride originally present in the lignite.

Jan 1, 1989

By King RP, Kientzler P

In recent years, ultrasonic comminution technology has been developed at the Utah Comminution Center. An ultrasonic grinding device was assembled and investigated. An ultrasonic transducer system has been significantly improved by using a special type of piezoelectric ceramic and preloading to 4.1 x le kPa to obtain maximum strength. The improved system provides constant and rapid vibratory promotion of fatigue fracture resulting in more effective breakage. The design principles for an ultrasonic mill are developed in this paper. Size reduction was successfully achieved in the ultrasonic nip-roll device for a variety of materials. Ultrasonic comminution has repeatedly demonstrated the capability of producing fine particles from a variety of materials. A comparison between ultrasonic grinding and dry ball milling of limestone showed that the ultrasonic device produced much narrower size distributions than the ball mill. This trend is especially obvious in the coarse size range where few particles remain, and in the fine size range where overgrinding is prevented. This behavior might have some interesting applications in areas other than mineral processing like powder metallurgy or material science where narrow and controlled product sizes are required for the successful elaboration of high-technology ceramics and glasses. Ultrasonic comminution has a significant advantage in the accurate control of the product size.

Jan 1, 1993

By Singh RN

The Bulli Coal Seam, located in the Illawarra Coalfield of New South Wales, has a long and varied history of sudden outbursts. From available information this problem has resulted in twelve fatalities over the last one hundred and one years, with over five hundred separate outburst incidents being identified. These incidents have varied in severity and intensity from the discharge of 1 to 2 tonne of coal, with a slight increase in gas emission, to the discharge of 200 to 400 tonne of coal with some 6,000 m3 of gas being liberated and large items of mining equipment being pushed 1 to 2 metres down the roadway.Geological features associated with these outbursts can be mapped on a regional and mine by mine basis, to provide some indication or warning. Similarly changes in gas content and gas composition can also be determined on a regional and mine by mine basis. However sudden geological changes (such as a 6.5 metre seam displacement within 15 metres) variations in gas content (such as 6 m3/tonne to 15 m3/tonne) and changes in gas composition (from 95% CH4 to 90% CO2) all within one mine does make the prediction or forecasting of outburst incidents exceedingly difficult.

Jan 1, 1998

By Matsuhisa Y, Sakurai W, Shimazaki H, Peiming H, Fukahori Y

Oxygen and carbon isotope mapping of hydrothermally altered wall rocks was applied to the blind ore prospecting of skam Pb-Zn deposits in the Kamioka mining district, central Japan, where the wall rocks consist of heterogeneous rock units. The results (8180sMow of -1.1 to +17.3%o and 613CPDB of -5.0 to +4.8%o for limestones, and 8180SMOW of -0.8 to +12.5%c for silicate rocks) show isotope zonations of the wall rocks with depletions in heavy isotopes (180 and 13C) toward the center of mineralization. The isotope zonations likely formed by interaction of migrating thermal waters with the wall rocks during the mineralization. The heavy-isotope depleted zone, which indicates higher temperature or higher water-to- rock ratio of the system, occurs in the footwall of a fault, indicating that the fault played the role of main conduit of the ore-forming fluids. A heavy-isotope depleted zone was also found in an area, where significant mineralization had yet to be identified. Recent drilling in this area has intercepted a zone with a grade of 16.0% Zn, 0.8% Pb, and 35g Ag per metric tonne at a depth of about 360m.

Jan 1, 1995

By Han Kook-Nam, Lawson F

The recoveries of the three cobalt minerals in the Mount Cobalt deposit, cobaltite CoAsS, erythrite CO3(AS04)8H20, and new cobalt mineral with a composition approximating 2CoO.CaO.Fe203.2As205.11H2O were investigated using physical and surface-chemical processes.Over 80 per cent cobalt recovery was achieved by tabling a cobaltite-mineralized sample, while about 76 per cent cobalt recovery was obtained by dry feed magnetic separation of a sample containing erythrite and the new cobalt mineral. The resultant primary magnetic concentrate with a cobalt grade of 5.5 per cent, was able to be upgraded to 14.4 per cent cobalt by regrinding .and a further magnetic separation.Electrophoretic mobility - pH responses for each of the three cobalt minerals were found to be similar. Each mineral remained negative over the pH range 3 to 11 and was most negative at mildly alkaline pH values.Cobaltite was floated effectively with amyl and ethyl xanthate collectors under acidic conditions at collector concentrations of 10-2M to 10-5M. Erythrite showed a similar flotation response using 10-sM amyl xanthate. The practical application of these laboratory separations to an industrial process is suggested.

Jan 1, 1976

By B T. Park, S D. Fundingslan, K W. Wangerud

The EPA National Risk Management Research Laboratory (NRMRL) Mine Waste Technology Program (MWTP) and the EPA Region VIII Superfund office are jointly conducting a field-scale technology demonstration of a two-step in situ treatment of the acidic Anchor Hill Pit lake at the Gilt Edge Mine Superfund site near Deadwood, South Dakota, USA. The project goal is to develop cost and performance data for the in situ treatment for potential application in long-term water treatment/management activities at the Gilt Edge site, and for potential application at other similar sites. Lime neutralisation of the pit using a Neutra-Mill was accomplished in the spring of 2001, with a resultant lime utilisation efficiency of about 71 per cent, and a typical throughput of about 1 tonne per hour using coarse, pebble quicklime and 1.4 tonnes per hour using finer, ground lime. Redox-mediated biotransformation treatment of the pit has been ongoing since May 2001. As of January 2003, denitrification is complete in the near-surface waters and about 90 per cent complete in the deeper waters. Bacterial sulfate reduction is expected to begin in the near future. This paper describes project activities, results, and lessons-learned to-date as well as future monitoring plans.

Jan 1, 2003