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By V P. Beskrovnaya

Tests for the development of a metals recovery technology from samples of a Russian gold-bismuth deposit were carried out. Gold, silver and bismuth assay reported 5.6 g/t, 3.0 g/t and 0.08 per cent, respectively. Two flow sheet options were pilot plant tested: gravity/cyanidation of gravity tailings with subsequent flotation of cyanidation/carbon-in-pulp (CIP) tailings, and gravity/flotation concentration with cyanidation/CIP of concentrates. Option 1 results showed lower gold, silver and bismuth recoveries (81.3 per cent Au, 55 per cent Ag and 74.0 per cent Bi) due to low flotation efficiency for cyanidation tailings. Therefore, a flow sheet involving gravity/flotation concentration to produce bismuth-gold concentrates (0.8 per cent Bi) with subsequent cyanidation/CIP was recommended. Gold, silver and bismuth recoveries obtained by this method to the combined gravity/flotation concentrate were 90.2 per cent Au, 83.3 per cent Ag and 80.2 per cent Bi of the ore, respectively. Overall gold, silver and bismuth recoveries were 83.0 per cent Au, 40.5 per cent Ag and 80.2 per cent Bi, respectively. Gold and silver recoveries to the cathode precipitate were 92 per cent Au and 48.6 per cent Ag (per operation). Reagents consumed for flotation were 0.1 kg lead acetate/t ore, 0.4 kg butyl xanthate/t ore, 0.2 kg T-80 frother/t ore, 0.02 kg sodium hexametaphosphate/t ore, 0.15 kg copper sulfate/t ore. Reagents consumption for cyanidation was 0.42 - 0.48 kg NaCN/t ore and 0.2 kg CaO/t ore. It was recommended to deliver bismuth concentrates after hydrometallurgical treatment to a smelter. Overall bismuth recovery including bismuth recovery achieved by pyrometallurgy was 60.0 per cent. However, it was obvious that delivery of bismuth concentrates to a smelter and their commercial treatment would be very expensive due to relatively high mass pull of bismuth concentrates (7.6 per cent of the ore weight). For this reason, thiourea leaching and hydrochloric acid leaching with subsequent cyanidation/CIP were investigated as alternatives to cyanide leaching. These two alternatives were proposed to enable optimal recovery of valuable metals from concentrates on-site. Recoveries obtained by thiourea leaching were 91.2 per cent Au, 90.5 - 91.9 per cent Bi and 77.0 - 78.1 per cent Ag. However, that method required considerable capital and operating costs. As an alternative, hydrochloric acid leaching with subsequent cyanidation was investigated. Test results showed improved gold, bismuth and silver recoveries, which were 94 - 95.9 Au per cent, 94 - 96 Bi per cent and 76 - 78 Ag per cent, respectively. Hydrochloric acid consumption was 100 kg/t concentrate or 7.6 kg/t ore. Current efficiency during electrowinning was about eight to 12 per cent. A recommended flow sheet involving hydrochloric acid leaching of concentrates, electrowinning of bismuth from solutions, recycling solutions after electrowinning and cyanidation of hydrochloric acid leaching cakes is described. Overall recoveries achieved by the proposed flow sheet were as follows: 84.8 - 86.5 Au per cent, 75.8 - 76.9 Bi per cent and 63.2 - 64.9 Ag per cent. Based on results from these tests, initial data for a bankable feasibility study and plant designing were developed.

Jan 1, 2007

By M Skead, H Michael, R Chase, A Davidson

Ashanti Goldfields CompanyÆs (AshantiÆs) most recent development is the Geita Project in the Lake Victoria Goldfield of NW Tanzania. It comprises six distinct gold deposits within two mineralised trends: Nyankanga, Lone Cone, Geita Hill (Geita trend) and Matandani, Kukuluma and Area 3 West (Kukuluma trend). Between 1936 and 1966, the Geita area produced an estimated 5.5 M tonnes of ore from five underground deposits at an average recovered grade of 5.3 g/t. The discovery of Nyankanga was made by Ashanti in 1996 from RAB drilling of a +100 ppb Au anomaly in laterite soil above ferricrete cover. The Kukuluma trend was discovered by SAMAX Resources (taken over by Ashanti in 1998) between 1996 and 1997 from RC drilling of a +80 ppb Au laterite soil anomaly. Oxide facies banded iron formation (BIF) of the Upper Nyanzian System forms prominent topographic ridges and is the dominant host lithology for gold mineralisation. The ridges are flanked by felsic tuff units which lie stratigraphically above. Syn-genetic lamprophyre (vogesite) and post-genetic felsic dykes are also seen in the Geita trend. At Nyankanga a granodiorite-diorite suite has intruded as dykes and sills into BIF from a plug centred on a WNW fault and has produced wallrock alteration assemblages similar to those seen in Cu-porphyry systems (potassic, propylitic, etc) as well as sulphide and gold deposition. However, the main ore-grade mineralisation (as in the rest of the Geita trend) is controlled by low-to-medium angle structures dipping north-west and north with numerous splays in the hanging wall. High-grade shoots at Nyankanga plunge to the west and to the north-west, being lithologically and fault-controlled respectively. At Geita Hill the higher grade shoots are controlled by fold noses in BIF dipping to the north. Free gold occurs within fractures of sulphides. The deposits of Kukuluma and Matandani occur on an ancient (possibly Cretaceous) erosional plateau and are related to two WNW to NW trending shear zones, discordant to the local strike of the BIF sequence. Complete oxidation occurs up to 120 m depth and there is a strong supergene component to the gold distribution. Primary gold mineralisation is divisible into two distinct assemblages: arsenopyriteûpyrrhotiteûmagnetiteûchlorite associated with brecciated cherts and pyrite associated with shaley banded ironstones. Area 3W is most likely the fault-displaced extension of the same mineralised trend and comprises thin, intermittent zones of high-grade gold mineralisation occurring adjacent to a ridge in banded cherts and minor BIF. Current resources (measured, indicated and inferred) for the project are estimated at 89.24 Mt at an average grade of 4.17 g/t (11.97 Moz of contained gold) at a 1.0 g/t cut-off grade. Of this 9.83 Moz is within the Geita trend and 2.14 Moz is within the Kukuluma trend. A resource of 2.74 Moz is from an inferred resource at depth at Nyankanga where the viability of an underground operation is being studied. Proven and probable reserves are 49.77 Mt @ 3.46 g/t (5.54 Moz) based on a $325/oz gold price providing a mine life of ten years at an average production rate of 500 000 oz per year. Reserve estimation was carried out using mineable polygons to select resource blocks based on a series of mining and costs parameters. In addition key cost parameters were tested to provide sensitivities for pit optimisations and pathfinders for negotiations with suppliers and contractors. Construction began in March 1999 and first gold is expected to be poured in the second-quarter 2000.

Jan 1, 2000

By C Zhang, G Si, J Oh, X Zhu

The presence of rock joints has a huge impact on the strength, deformability, and permeability of fractured rock masses by providing surfaces of weakness on which further deformation are more prone to occur, and by serving as the major channels of water flow due to low matrix permeability. In earlier studies, water flow-through rock joints is often assumed as laminar flow between two ideal smooth parallel plates, and the well-known cubic law was derived and widely used to characterise the hydraulic behaviour of rock joints. However, natural rock fractures are irregular and of spatially varied aperture. Thus, the concept of equivalent hydraulic aperture was introduced to modify the cubic law. Numerous works have been conducted on the relation between hydraulic aperture and mechanical aperture incorporating various geometrical parameters. The surface roughness is one of the most sensitive factors for water flow-through rock joints. The aperture distributions are irregular in natural roughed fractures relative to the parallel plates. Barton et al (1985) and Olsson and Barton (2001) incorporated the joint roughness coefficient JRC in evaluating hydraulic aperture and proposed an empirical equation based on fluid flow tests. However, their equations do not conform to the dimensional consistency. Many other researchers (Zimmerman and Bodvarsson, 1996; Xiong et al, 2011; Li et al, 2019) considered aperture distributions in their equations. But the aperture distributions change during shear was always neglected. The contact of rock joints also has a significant impact on the hydro-mechanical behaviour of rock joint, since fluid tends to flow-through a rough joint along connected channels while bypassing the contact obstacles with tortuosity. Nonetheless, previous research mostly considered joint roughness or aperture changes based on 2D joint profiles, while the contact and tortuosity based on 3D surfaces were often overlooked. Only a few works have been made on quantifying the effect of contact area on flow behaviour (Walsh, 1981; Zimmerman et al, 1992; Zimmerman and Bodvarsson, 1996; Yeo, 2001), and mostly ignored contact area change induced by shearing and the associated impact on flow behaviour. Summarily, the quantification of fracture geometry effects on water flow in single rock joints still needs further investigation, especially when considering coupled shear-flow processes. This paper, therefore, aims to study the impacts of contact area and aperture distributions of the single rock joint on the flow behaviour. The evolutions of contact area and aperture distributions induced by shear are considered. Then, an improved model for estimating the hydraulic aperture with the mechanical aperture incorporating the above factors is developed. Finally, a series of shear and shear-flow tests are conducted on artificial joint samples and the model performance is verified by comparing against the results of experimental tests.

Nov 29, 2022

By D Ray, D Brett

A clay-capping trial was established in 1996 on Magazine Dump at the Mt Lyell Copper Mine. The trial was initially constructed under the Mount Lyell Remediation Research and Demonstration Program, a co-operative venture between the State and Federal governments. The detailed engineering design for the clay cover included the following features; reshaping and compaction of dump batters, 5 m vertical bench interval, overall side-slopes of 2.5:1, emplacement of clay in four 150 mm lifts, compaction by a 10 t vibrating roller or ætrack rollingÆ on batters with density testing for quality control. A small section at the base of the dump ( The trial also generated certain unexpected findings. Field permeability tests on the cover yielded uncertain results and oxygen remains available throughout the dump. The flow data indicate that, while total outflow has decreased as a result of storm shedding, inputs from groundwater and batter infiltration are still significant. Outflow during the driest weeks of the year may have risen following capping. Detailed assessment of the data is hampered by insufficient pre-capping information; however, there is a possibility that conductivity flux emitted when flows in the receiving environment are at their annual minimum is unchanged or worse post-capping.

Jan 1, 2003

By R Hoeppel, D Harimon, A Fisher

This paper examines the importance of examining the relationship between biology and geochemistry when designing a biopile to treat alkaline soils impacted by petroleum hydrocarbons. At a site in Nevada a large, unlined pit was constructed in a loamy sand soil and filled at regular intervals with a mixture of jet fuel, lubricating oils and waste solvents which were set on fire by the local fire department for training purposes. During its period of operation numerous chemicals were also dumped into the pit for disposal purposes, including dichlorobenzene and various chloroethylenes. As a result of these activities a large groundwater contaminant plume was formed. As a part of the site remediation process a decision was made to perform a limited source removal and excavate the top three to four metres of contaminated soil from the burn pit and place it in an engineered biopile. The location of the training pit is in a heavily mineralised basin where the background sulphate level in groundwater exceeds 5000 ppm. Due to naturally occurring biodegradation of the petroleum hydrocarbons a large portion of the sulphate was converted to sulphide which deposited in the soils as marcasite in the anaerobic soils. The initial attempt at soil remediation was to use a forced air treatment scheme that had worked well in small scale laboratory testing. Unfortunately, when attempted in the field on a large scale, marcasite reacted with atmospheric oxygen resulting in internal biopile temperatures exceeding 90¦C resulting in the virtual sterilisation of the soils without remediation occurring. In order to solve this vexing problem Pintail Systems, Inc developed an anaerobic culture that allowed the pile to be operated under anaerobic conditions. Within three months the biopile successfully demonstrated on a large scale significant biodegradation of the refractory petroleum hydrocarbons.

Jan 1, 2004

By P Khalkho, M Singh

Rock masses when subjected to uniaxial or triaxial cyclic loading (eg in hydraulic running tunnels, during retrieval and injection of oil and gas from storage underground caverns and haulage roads), the material has a tendency to fail in fatigue. In order to design safe and reliable underground structures, the determination of brittleness under such loading conditions becomes a pre-requisite. Brittleness influences strongly the failure process and makes the rock mass behaviour complex under different tunnelling and mining activities. Brittleness Index is a term to quantify the brittleness feature of a specimen. In the present study, an attempt has been made to quantify the brittleness of jointed specimens using different brittleness criteria. The joints of the model jointed specimens were oriented at an angle of θ=15° normal to the loading direction, each having three different JRC’s=2–4, 12–14 and 14–16. The specimens were tested under triaxial conditions in incremental complete cyclic test scheme performed at displacement-controlled mode. Different brittleness criteria were used ie stress-strain dependent brittleness index, Young Modulus approach and energy-balance based mechanism. It was observed that energy-balance based mechanism which consider the post failure behaviour is more descriptive to reflect the whole variation of brittleness from sheer brittleness to ductility.

Nov 29, 2022

By C Staak, H Mischo, A Fichtner, F Reuter

In mining and remote areas of resource industry, there has been a development towards lacking emergency medical first aid response, that creates a potential disadvantage for patients after work accidents and other medical emergencies compared to standard population. This raises the question how a professional emergency medical coverage can be provided underground, taking into account lacking medical professionals in small resource companies combined with long rescue times. Aiming on the closure of this gap, a team of the mine rescue brigade from the Research and Training Mine Reiche Zeche (Forschungs-und Lehrbergwerk (FLB) Reiche Zeche) of the TUBAF Technische Universität Bergakademie Freiberg in Freiberg/Germany and its cooperating emergency departments of the Freiberg District Hospital and the Zeisigwaldkliniken Bethanien Chemnitz developed a totally new rescue concept using elements from tactical medicine and advanced emergency medicine combined with a specifically designed compact equipment and a highly standardised teaching curriculum. A fully new standardised and condensed tactical medical approach was developed including specifically adjusted equipment, and was taught in a didactically optimised way within 16 lessons in two days. Objective Structured Practical Examinations (OSPE) using manikins and simulated patients were conducted and compared to the identical exam of the reference group, which consisted of advanced paramedics. The standardised tactical medical scheme includes vital functions and body checks, advanced life support, nasal and intraosseous drug application, supraglottic airway management, artificial ventilation, thoracocentesis, bleeding control including tourniquet, fracture repositioning and splinting, transport bedding and thermal preservation. The developed Tactical Medical Mining Rescue (TMR) concept was subsequently included in the German guidelines for mine rescue services in 2022 and is already implemented in many companies in Germany and several international projects.

Sep 1, 2024

By B D. Sowerby, N G. Cutmore

Improved process control can be achieved through the accurate and reliable on-line measurement of critical process parameters in real time. Over the past few decades on-line analysis techniques have been developed and applied in the mineral and energy industries for the measurement of process stream composition, mineralogy, particle size and flow rates. This has led to increased throughput and product quality while reducing processing costs and minimising emissions. The support of a sustainable mineral processing industry will require the further development of on-line analysis and control technologies. The application of developments in instrumentation combined with improved control strategies will lead to improvements in process efficiency resulting in large economic benefits to the industry, reduced energy usage and lower process emissions. There is a clear convergence of interests in being able to better measure and control minerals processing in terms of the triple bottom line of economic, social and environmental impacts. Technology is increasingly becoming available enabling measurement across the entire spectrum of minerals processing from mining to hydrometallurgy and pyrometallurgy. CSIRO is developing a range of these new technologies. A number of these developments are discussed in the present paper, namely: on-line particle size analysis and acoustic emission methods to enhance the control and optimisation of grinding circuits; on-line mineralogy of dry powders and slurries; on-line bulk elemental analysers for application on conveyor belts and in smelters; and the development of new sensing technologies for sorting base metal ores.

Jan 1, 2002

By M S. El Salmawy

In order to develop the HF-free flotation reagent system, the main objective of this investigation was to study the possibility of separation of quartz from feldspar using non-ionic surfactants as the collector. The non-ionic surfactants used were polyoxyethyl cethyl ether (PECE) and polyethylene glycol monocethyl ether (PGME). The flotation behaviour of quartz and microcline with PECE and PGME was investigated. Each surfactant was a good selective collector for quartz with its recovery being influenced by pH and surfactant concentration. Quartz is floated favourably by both types of polyoxyethylene non-ionic surfactant whereas microcline was not so much. The floatability of quartz increases as the oxyethylene length of surfactants increases. Zeta potential measurements in the system of PGME/mineral were also carried out. It was determined that in the absence of PGME the points of zero charge for quartz and microcline should be approximately at pH 2.5 and 1.8, respectively. The addition of PGME to the system causes both minerals to become less negatively charged. Differences in the zeta potential value between quartz and microcline, in the presence of PGME, were detected. It can be suggested that the interaction of the oxyethylene group to the microcline surface should not be as strong as that to the quartz surface. In the mixed surfactant system of PGME and dodecylamine acetate (DAA), a small addition of DAA causes drastic enhancement of quartz flotation in the wide pH range of 1 ~ 10. In the mixed surfactant system selective flotation of quartz from microcline would be anticipated at pH

Jan 1, 2005

By Whittaker B. N, Reddish D. J

This paper presents the physical modelling results of subsurface fracture development associated with Iongwall mining operations and an application of image processing techniques to interpretion of the results. Physical modelling results haióbeen obtained by employing a large sand and plaster model loaded purely by gravity as a means of fracturing the subsurface strata above the longwall excavation. The results have shown fracture development and crack propagation as a longwall face advances and demonstrated that the strength of stratified rocks, the presence and position of a weak band-, and the extraction thickness, have significant effects upon the overall fracture patterns above the excavation. Binary images of fracture patterns were scanned from the black and white photographs of the tested models using an image analyser coupled to a video camels. These images were manipulated by a custom written C program which allows the images to be processed in both vertical and horizontal direction. The images were filtered to quantitatively differentiate between vertical and horizontal fracture intensities. The vertical fracture intensity is particularly important as vertical fractures are considered to provide the main avenues for surface and subsurface water inflow into the excavation. The use of the image analysis techniques has shown a promising improvement in image enhancement and in model results interpretation in a quantitative manner. The numerical nature of the image analysis results will allow further statistical comparison with other modelling techniques to be undertaken and significantly increase the scope for use of the modelling technique results.

Jan 1, 1992

By S M. Aminossadati, C M. Stewart, M S. Kizil

Mine ventilation models are now an accepted component of most mine management systems. However, modern ventilation models also represent a highly structured spatial data source, defining underground pathways and connections across a mine. This creates opportunities to extend the use of network models beyond ventilation design, by using critical path algorithms to find pathways such as minimum distance or minimum time.This paper explores the use of ventilation network models to automatically analyse and calculate potential emergency escape routes. A variation of Dijkstra’s algorithm is used to predict complex pathways between any two points across a model, representing an escape route from an emergency area (such as a fire) to a safe location (such as the surface or a refuge station). Weighting can be assigned to paths to represent potential travel speed, obstructions or preferred routes. Finally, emergency considerations such as smoke or gas in some parts of the mine can then be incorporated into the pathways to force the algorithm to avoid dangerous routes and specify safer pathways. Ventsim is used to visually show example results.Emergency egress pathway prediction using ventilation network models can provide an efficient way to quickly predict the quickest or most efficient escape routes for emergencies or planning purposes.CITATION:Stewart, C M, Aminossadati, S M and Kizil, M S, 2017. Emergency egress pathway prediction using ventilation models, in Proceedings Australian Mine Vent Conference 2017, pp 57–62 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 28, 2017

Cerro Matoso (CMSA) in Colombia produces ferro-nickel from lateritic ore containing approximately three per cent nickel, using a Rotary Kiln - Electric Furnace (RKEF) process, in which the calcining of the mineral within the kiln is second in importance only to the smelting of the mineral in the Electrical Furnace. This article discusses the installation and operation of an expert system to control the kiln of CMSA. In the CMSA process, the run-of-mine ore is crushed, homogenised, dried and mixed with a small percentage of coal, before being heated up to 900¦C in a rotary kiln in the presence of natural gas mixed with air in a controlled proportion (air/gas constant ratio). The final objectives of the process are the following: ò To reduce to a minimum the iron and nickel oxides in order to convert these into metallic ions; this is a reduction process to facilitate largely the smelting in the electric furnace. Since the reduction is made with natural gas, it is much more economical than the subsequent complete reduction in the electric furnace, since electrical energy is much more expensive by unit of processed mineral. ò To heat the mineral as much as possible to facilitate the subsequent smelting. ò To eliminate totally the moisture content of the ore. An expert system with fuzzy logic was commissioned in 1994 for the control of the kiln and it has operated with good results ever since.

Jan 1, 1996

By Semple DG, Leach TM

A continued exploration programme has further defined the geology of the Tolukuma vein system, verified the resource indicated by Newmont, and identified potential for additional mineralisation. The resource at Tolukuma Hill, designated as Zone C, is a measured 440,000t @ 17g/t Au and 46g/t Ag with an additional indicated resource of 120,000t @ 16g/t Au. A diatreme breccia localised at an intersection of structures, and a relationship of gold to base metal sulphides, are highly indicative of a porphyry association. Typical epi-thermal features such as crustiform banded quartz and quartz pseudomorphing. platy calcite are also present and locally contain lesser gold mineral-isation. Pre-existing dilatant structures have acted as a host to the ore fluids, resulting in the formation of the semi-continuous Tolukuma-Gulbadi veins over a 1100m strike. A fluid flow model suggests that mineralising fluids were sourced from the diatreme margins and migrated laterally along dilatant structures. Bonanza gold grades are derived through fluid quenching in the flexure between a hanging wall split which hosts much of the Tolukuma Hill resource and the feeder graben structure. Thus, the relationship between the pre-mineral structural geometry and fluid upflow at the margins of a diatreme breccia, controls the ore setting. Potential for more ore remains within the Gufinis and the 120 veins as well as in the outlying Prospects.

Jan 1, 1994

By Storey AG

Following initial plant scale work on the development and performance of 'spray' oil lances, a full scale room temperature model of the blowpipe-tuyere region of a blast furnace was built to study the basic aerodynamic features of auxiliary fuel injection procedures. Mobilwax 2305 was used as a substitute for Bunker C oil fuel in view of its similar physical properties and the fact that the atomised droplets could be frozen in flight and size, distribution analyses made for various operating procedures. It was shown that secondary atomisation processes far outweighed the importance of any primary atomisation procedures in determining mean Sauter Diameters particularly at high windrates typical of current blast furnace technology. It was also found that good spray dispersions across the blow pipe could only be obtaind for liquid fuels and that the lateral rate of spray dispersion was substantially enhanced by primary atomisation procedures. Mean particle diameters of sprays were found to be predictable on the basis of elementary stability theory and fell within the size range necessary for good combustion at all liquid fuel rates studied. The possible effects of high oil injection rates on flooding phenomena in the furnace bosh were considered. Comparisons show that high oil rates can lead to significant increases in the hanging factor (e.g. 'V 10% at 135 kg oil/thm) owing to increased gas flow rates/thm resulting from the presence of hydrogen.

Jan 1, 1975

By C Fountain

It is commonly known that copper smelter terms include penalties if the concentrations of elements, such as arsenic, mercury and fluorine, exceed stipulated limits. It is less commonly known that the behaviour of these elements in the smelters can depend on the processes used to treat the concentrate. The principle behind the penalties is to compensate the smelters and refineries for additional costs caused by the presence of the penalty elements, but these costs will vary depending on the process used and the location of the smelter.The issues caused by the minor elements include effects on the occupational health of smelter workers, increased environmental disposal costs, increased operating costs and reduced cathode copper quality.The effects of minor elements can be surprising. High levels of arsenic in concentrate are considered undesirable, but some smelters add arsenic to anode copper to improve the performance of the refinery.Excess concentrations of some elements will result in rejection of concentrates by smelters. China has blanket import bans on copper concentrates with concentrations of lead, arsenic cadmium, fluorine and mercury exceeding specified levels.This paper will review the behaviour of minor elements in smelters and refineries, explaining the deleterious effects of each of them, to provide a greater understanding for people and organisations wishing to market copper concentrates.CITATION:Fountain, C, 2013. The whys and wherefores of penalty elements in copper concentrates, in Proceedings MetPlant 2013 , pp 502-518 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 15, 2013

THE treatment by chlorination of the Mount Morgan Gold Mining Company's ores was first accomplished, early in 1886, by a works having a capacity of 25,000 tons per annum. Shortly afterwards another works was established, capable of dealing with 50,000 tons per annum. The extraction of gold was originally successful and satisfactory, but running expenses were high, averaging £2 19s. 6d. per ton of ore treated. These works were believed to be the largest chlorination plants in the world at that time. As might have been expected, the mechanical details and chemical process had not been perfected, and, moreover, both works were hurriedly built, and operating expenses were not then considered of such prime importance, as the ore at that time was of very high grade; the large quantities of low grade ore since dealt with not being then considered, since the bulk of it was not even known to be in existence. These two works consisted of rock-breakers, high speed rolls, screens, elevators, &c., for crushing; a large number of small handrabbled reverberatory furnaces for roasting; one-ton chlorination barrels and three-ton leaching vats for chlorination. The transport of ore from crusher to furnaces, from furnaces to chlorination barrels, and the emptying of leaching vats was effected entirely by hand labour. The system of chlorination was what was, known as Mears process, chloride of lime and sulphuric acid being used in the chlorination barrels, and as the time allowed...

Jan 1, 1911

By Milner SC

Four quartz latite rheoignimbrite units (units I to IV) mapped in the Goboboseb Mountains have been traced to their eruptive source, the Messum intrusive complex; this is a complex multistage ring structure (18 km diameter) with well defined gabbroic, monzonitic, and syenitic intrusive phases, and a central ring zone containing mixed rhyolitic to latitic agglomerates. Three of the four quartz latite units are correlated with the upper and lower (2 units) Springbok quartz latites outcropping some 90-130 km north of McIsum. This implies minimum volumes of 300-500 km for wits I and III (Lower Springbok) and 2200-2600 km for unit IV (Upper Springbok). This latter unit is still ti 300 m thick at its outcrop limit, some 130 km from Messum. Each of the four units represents single cooling units. Lithologically, each can be divided into three zones: A basal, dark grey to black flinty or glassy zone, often with highly attenuated fiamme (ressembling flow banding); a central massive and strongly recrystallised zone; and an upper variable zone which exhibit breccias, contorted flow banding, and amygdaloidal to pumiceous clasts. Their overall characteristics tend to be intermediate between ash flows and lava flows. The rheoignimbrites are interpreted as the oproducts of dense, high temperature (950¦-1100 C) ash flows which underwent rheomorphism and lava-like flow prior to their final cooling.These large scale eruptions are related to the initial rifting of Africa and S. America, possiby in response to a major hot spot.

Jan 1, 1990

By J E. Everett, M L. James

When iron ore is crushed and split into lump and fines components, there are systematic differences between the lump and fines grades. Generally the lump product is richer in iron and lower in the other minerals, compared to the fines product. The grade differences between lump and fines, together with the lump percentage, are referred to as the ælump algorithmÆ. Mine estimates of grade, based on exploration or blasthole drilling, relate to head grade. The ælump algorithmÆ predicts lump and fines product grades from the head grade. This knowledge is important when developing mine plans. Different ore types can be expected to have systematically different lump algorithms. Previously, lump algorithms for specific ore types have been estimated by running the crusher with a single ore type over a sample period. This method is costly, interferes with production, and yields results of limited statistical power. It has been found that weighted-least-squares (WLS) multiple regression can be used to ascribe lump algorithms to different ore types, provided sample periods have sufficiently varied ore type mixes. This study discusses the method and its application to the analysis of Mining Area C crusher production records to estimate the separate lump algorithms, which could be applied to the different ore types. The analysis has enabled the set up of lump algorithms in the production system, to improve the grade control of lump and fines product. Some other relevant applications of the WLS multiple regression approach are also considered.

Jan 1, 2005

By D L. Kennedy

Many aspects of the physical layout of manufacturing plants and storage facilities for explosives are governed by so-called quantity-distances tables. Both the British and the American tables were originally derived from an analysis of the injuries and the building damage documented by an early 20th century compilation of significant accidental explosions. However, progressive changes in explosive process technology and in building techniques have reduced the relevance of much of this historic data set. Extensive scientific research has been conducted over recent decades to characterise the potential injuries and damage from accidental explosions under more modern conditions. This presentation will showcase some of this research.**This is an abstract only. No paper was provided for this abstract**

Nov 8, 2011

By D Cliff

"It has been 17 years since the mine disaster at Moura No 2 Mine in Queensland. Recent disasters in the USA and New Zealand prompt the question what has changed since 1994. This paper att emptsto answer this question and identify areas that need improvement."

Jun 1, 2012