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By Armoo K, Tran T

Cementation has been widely used in several hydrometallurgical processes for recovering gold and silver from process liquors. The process is electrochemical in nature, in which gold and silver are precipitated from the solution using less noble metals such as zinc, iron and copper. This paper summarises the current practice of gold cementation from cyanide liquors using zinc powder. Various developmental studies on the cementation of gold and silver from various systems (chloride and bromide) are also reported.

Jan 1, 1991

By Zingano A, Costa J. F

Brazilian amethyst production is mostly obtained from underground mines in the southernmost part of the country, involving approximately 6000 miners and generating an income of US$ 20 million per year. Amethyst-bearing geodes are hosted by Cretaceous continental flood basalts of the Serra Geral Formation. The economic zone occurs in the massive (colonnade) intermediary section of the Sao Gabriel Basalto. The tunnels and stopes follow the occurrence of geodes leading to an erratic and complex layout. A ground control survey revealed excessive roof convergence. Topographic results show excessive roof deformation and some roof falls have already been reported. To understand the ground conditions, prevent roof falls and better define the pillar dimensions detailed geomechanical mapping was carried out using the scanline method. Uniaxial compressive strength tests provided complementary information for rock mass classification. Results of the geomechanical classification were used to modify the mining layout taking into account the roof and pillar geomechanical characteristics. Retreat pillar mining minimised ground instability.

Jan 1, 1997

By Sneddon J

This Is not a highly technical paper, but rather an attempt to give a general outline of coal mining for the benefit of those present who may have little or no experience in the industry, and is intended to give some general knowledge which may help to a better understanding of the problems of the industry. A knowledge of the disposition of workable material is necessary to give a comparison with other mining practices. Coal Is usually found in comparatively fiat seams of varying thickness, whereas other minerals are generally found in highly inclined lodes of variable width. However, even in comparatively flat seams unaffected by faulting, grades can, and do, vary greatly over short distances.This variation causes many local problems in working the small area affected. Even very steep seams, and some are much steeper than 1 in 1, vary considerably not only in grade, but also in direction of grade and level course. This is probably caused by folding during alteration of the shape and form of the basins after deposition.These swellies are common to most coal seams and vary only in extent. This type of variation in grade and direction of grade, while common to most ore bodies, is a matter of great importance in coal mining when it is considered that roadways are driven in the seam itself and have to be graded and made suitable for haulage purposes.The area of ground involved in an individual coal mining operation is often very large; many times larger than most metal mining propositions, and often comprises many thousands of acres.When it is considered that the specific gravity of coal may be only one-fifth of that of some ores mined, and the coal seam may be five or six feet in thickness, the vastness of the area necessary for continuous mining operations over many years will be realised.To achieve comparable outputs, with about five times the bulk of material to handle, much more ground and working places must...

Jan 1, 1947

By Ohga K, Isobe T

Basing upon many and long practical experiences of gas drainage from coal seam and results investigations on the gas flow through in si-tu coal seam using tracer gases,it became clear that solid coal itself is hardly gas permeable or has extremely low gas permeability. Almost all of gas flows from a coal seam into boreholes through fracture net- works intersecting with them.Primary and secondary fractures in coal seams differ in their size and continuity from place to place according to differences of the coal strength and the stress conditions. A lot of gas can be drained through boreholes which intersect with many and/or wide fractures. A mathematical model for gas flow from a coal seam to a borehole through a discoidal fracture is proposed. From the numerical analyses,the apparent radius of the discoidal fracture in this model is shown to be a good indication of the gas drainage ratio. In addition to this,an atempt to make fractures around a borehole using high velocity water jet(ca.lmm dia.,300-700atm., 100-200 1/min.) is introduced.

Jan 1, 1982

By Jagger N. D

Lead residue from the Zinc Leach Plant at Pasminco's Port Pirie Lead Smelter was previously filtered on a vacuum drum filter and further dried in a gas fired rotary kiln prior to stockpiling and transport to the Sinter Plant. This process involved several materials handling stages, recycled significant amounts of zinc and often resulted in poor environmental conditions. These problems have been overcome by pumping the thickened leach residue approximately 450m to the Sinter Plant where it is filtered in a Larox Automatic Pressure Filter. The filter cake is discharged onto a conveyor belt, held in a storage hopper and then fed directly to the main sinter plant feed stream. Filtrate is returned to the process for additional zinc recovery. The laboratory and pilot plant filtration results are briefly discussed and compared with the operating plant data. The filter installation and ancillaries are described in detail along with the commissioning, operating and maintenance experience over the past 4 years. This installation has overcome the environmental and materials handling problems and resulted in annual savings of approximately $1 million.

Jan 1, 1989

By Wilson J. R

The main mining method employed at Mt Lyell is sub-level open stoping with a typical extraction level interval of 100 m and sub-level intervals of 30 m. Currently, pillar blasts provide the major portion of broken ore and firings are in the order of 200 000 to 300 000 tonnes while future firings of 500 000 to 300 000 tonnes are planned. Improvement of blasting techniques in these mass firings has been necessary for the following reasons. 1. Extremely wet ground conditions have adversely affected ANFO performance and placed extreme pressure on the charging and priming phases. 2. As pillar blasts increase in size the problems of wet ground conditions are accentuated resulting in very slow loading of wet upholes with cartridged gelignite and unreliable charging of the remainder with ANFO. 3 Fragmentation in pillar blasts has suffered because of the above, result- ing in increased secondary breaking costs and difficulty of extraction.

Jan 1, 1977

By Dickson T. J

Slag cleaning is an important part of the pyrometallurgical operations at the Kalgoorlie Nickel Smelter. It is a complex system with many streams of different phases and composition. Some of these streams are very difficult to control and/or monitor. Through the use of a statistical computer package, called Minitab, key relationships affecting the economical operation of the slag cleaning process have been found. Data for the statistical analysis was collected from all possible variables around the appendage.

Jan 1, 1991

By Grantham DL

ABS'TRACT For a number of years research efforts have been directed towards improving the efficiency of sampling and analysing coal mine roadway dusts. In the past decade the practicality of rapid, on site analysis of the incombustible content of these dusts using a radioactive technique has been receiving close attention both in Australia and overseas. Accurate measurement of the total incombustibles present is only possible by time consuming chemical methods. As the densities of the solid incombustible materials are greater than that of coal, they absorb a higher proportion of incident low energy gamma radiation than does coal. The amount of such radiation "back scattered" from mine dust samples is therefore inversely related to their average densities, and hence to their incombustible contents. This phenomenon can be used as a measure of incombustible content by employing an appropriately designed and calibrated instrument.

Jan 1, 1981

By Hutton A. C

Quantitative X-ray diffraction (XRD) analyses using the Rietveld method, a standardless technique for full XRD pattern fitting, showed the mineralogy of the eastern Queensland Tertiary lacustrine oil shale deposits is dominated by detrital cla

Jan 1, 1994

By P Commander

Western Australia is a major exporter of minerals, which places significant economic and environmental responsibility on Government and the stateÆs mining industry. Moving into the 21st century, mineral production in Western Australia is $14 billion accounting for 50 per cent of the stateÆs export income. There are over 60 large-scale mining operations distributed throughout the arid regions of the state (less than 300 mm/year rainfall). There are four key mineral provinces in arid Western Australia including the Pilbara (iron ore), Murchison (gold), Northern and Southern Goldfields (gold and nickel). These provinces have significant differences, particularly in respect to groundwater demand from mining and mineral processing, aquifer systems that are utilised, and approaches to groundwater management. The arid nature of the stateÆs interior and subsequent lack of surface water resources has required substantial groundwater resource development by the mining industry. A variety of aquifers have been explored and utilised ranging from shallow alluvium and calcrete, discrete fractured zones in bedrock, concealed palaeochannels and inland sedimentary basins. Groundwater usage by the mining industry is about 150 GL/year with most abstraction related to mine dewatering, mineral processing and dust suppression. Groundwater abstraction in Western Australia is regulated by the Water and Rivers Commission. In the Goldfields, the depletion of brackish (>2000 mg/L) and saline groundwater from storage is permissible, as mining is considered the beneficial use for groundwater which may be as much as 200 000 mg/L. In contrast, the low salinity groundwater of the Murchison and Pilbara is allocated on a sustainable basis. The role of monitoring and ongoing aquifer reassessment is crucial in water management, in evaluating the condition and performance of stressed aquifer systems. Mining operations face a variety of water resource issues ranging from insufficient availability for processing to excessive mine dewatering. These issues also change as a mine operation proceeds through its development, commonly starting with a deficiency and moving into surplus as deeper pits require more dewatering. Operating mines have to contend with three main issues: water supply, wastewater disposal and contamination of local water resources. In contrast, post closure issues are related to aquifer recovery or re-establishment of groundwater equilibrium, development of pit lakes in mine voids and isolation of waste products and associated seepage or run-off.

Jan 1, 2003

This paper outlines some of the recent developments in Spiral Concentrator design, with particular reference to the range of Reichert spirals supplied by Mineral Deposits Limited, typical applications, and test or operating data, are also provided for the different series of spirals now available.

Jan 1, 1978

Sublevel open stoping was introduced at Rosebery in 1972; most of the stoping prior to this was horizontal cut and fill. Sublevel open stoping presently accounts for 65% of the Rosebery underground production of 560 000 tonnes per year. This primary stoping technique leaves 50% of the ore in the crown and transverse pillars. The methods used in pillar recovery to date are reviewed and comments made on the success of these operations.

Jan 1, 1982

By Allnutt S. L, Carswell J. T, Mutton A. J

The Dugald River Zn-Pb-Ag deposit occurs within the complexly deformed and metamorphosed sediments of the Middle Proterozoic Cloncurry Terrane, Eastern Succession, Mount Isa Inlier. The sedimentary sequence comprises a thick package of variably carbonatic argillitic and siliciclastic sediments of the Corella Formation, Lady Clayre Dolomite and Knapdale Quartzite. A slate and calc-argillite unit locally referred to as the Dugald River Slates is the host to the economically significant deposit. The deformational history of the Dugald River area involved three phases of ductile deformation. The present geometry of the Dugald River Main Lode is recognised as a strike extensive steep westerly dipping tabular sheet, within which a steep north westerly plunging zone of pronounced thickening is evident. This zone is interpreted to have formed during folding via remobilisation of the sulphides into a shoot-like body, the geometry of which was controlled by stretching associated with the folding. Further modification of the shoot and sulphide re-distribution has resulted from late phase transgressive shears. The sulphide mineralisation is characterised by three distinctive sulphide types, laminated, banded and breccia, the distribution of which define two broad zones. The northern zone is a narrow I - 5 m thick stratabound unit comprising finely laminated and banded sulphide mineralisation within a well bedded fine grained argillite sequence. This is part of the Lady Clayre Dolomite sequence and is a predeformational precursor form of mineralisation. The southern zone comprises the thickest development of mineralisation (up to 30 m) characterised by slate-sulphide breccias and veins derived from complex polyphase remobilisation of the sulphide mineralisation. It is this zone which forms a stratabound locally transgressive body within the high strain Dugald River Slates and which contains the main body of economic mineralisation. Sulphide mineralogy comprises sphalerite, pyrite, pyrrhotite, galena and traces of chalcopyrite, pyrargyrite, tetrahedrite, marcasite and arsenopyrite. The present resource for the Dugald River deposit stands at 38 Mt grading 13.0 per cent Zn, 2.1 per cent Pb and 42 g/t AS. The Dugald River Zn-Pb-Ag deposit is regarded as an example of a syndiagenetic stratabound sulphide accumulation which, as the result of polyphase deformation and upper greenschist to middle amphibolite facies metamorphism, has undergone extensive remobilisation and Rccrystallisation.

Jan 1, 1993

By De Jong HJ

During the forthcoming reline of No.3 Blast Furnace at the Newcastle Steelworks of the Broken Hill Proprietary Co. Ltd., facilities for the screening and weighing o' coke will be installed. The equipment is needed to optimise the sizing and the quantity of coke immediately prior to it being charged to the furnace. Up till the time the furnace was blown out in November, 1982, coke was charged to the furnace by volume, ie by skip fulls only. This resulted in variation to the ore/coke ratio charged due to bulk density changes and erratic skip filling levels. This in turn affects the heat balance of the furnace and causes fluctuations in hot metal chemistry and temperature. A coke rate penalty has to be paid also. Coke layer thickness in the furnace burden cannot be controlled closely, resulting in loss of control over gas distribution in the furnace. A grizzly type screen was incorporated in the skip loading chute but this ineffective method left a great amount of fines with the coke being charged to the furnace. Furnace permeability was therefore reduced, particularly in the hearth.

Jan 1, 1984

By Scherbatsky VB, zon BM, Babushkin NM, Kitaev BI, Shabel&apos

The structure and hydrodynamics of the raceway zone of a blast furnace was studied on a cold model representing a sector containing two tuyeres. The model differed from the usual in that it was prov- ided with continuous flow of the coke layer at pre- determined rates, had provision for changing the tuyere parameters (diameter, protrusion, inclinat- ion) and irrigation of the layer with liquid. A combination probe was developed which per- mitted simultaneous measurement of the pressure field both across the area and through the height of the layer as well as determining the topography of the raceway. The velocity fields in the layer were measured with a specially made impulse thermo- anemometer. The determining criteria of the model were taken as the relationships between the energy of the blast and the particles, the dimensions of the raceway and the cross-section of the tuyere. The model established the effects of the tuy- ere structural parameters, blast parameters and amount of liquid products of smelting on the con- figuration of the raceway, the structure of the layer, pressure and velocity fields in the vicinity of the tuyeres and in the vertical direction through the layer. The properties of the raceway formation and the structure of the layer in motion have been clarified.

Jan 1, 1981

By Quast K. B

The effects of metal ion addition rates and contact time on the activation of synthetic sphalerite using copper, cadmium and silver ions were determined in order to investigate the exchange characteristics at the mineral surface. The stoichiometry of the adsorption indicated that the activation of sphalerite involved both a simple ion exchange and redox process in which the activating ion and oxygen were reduced, and the mixed-sulphide surface was oxidised to produce elemental sulphur and a metal-deficient sulphide surface. Unactivated sphalerite was shown to be relatively hydrophilic, with recoveries usually less than 20 per cent for a five-minute float. Activated sphalerite could be readily floated without the use of a conventional collector. This inherent flotability of the activated sphalerite had previously been associated with the formation of a metal-deficient sulphide layer; however, this study emphasizses the significance of the surface oxidation processes occurring.

Jan 1, 1993

The aquifer at Phosphate Hill, north-west Queensland, presents special management challenges. The site contains a phosphate rock mine, fertilizer plant and camp. All of the site water is provided by the Duchess Embayment Aquifer, located within the Burke River Outlier of the Georgina Basin. The Duchess Embayment is a triangular shaped, Cambrian marine sedimentary basin consisting of siliceous and calcareous phosphorites, shales, siltstones and sandstones. It is fault-bounded on all sides and has a regional dip of 5¦E. The aquifer is largely confined to the siliceous facies of the Beetle Creek Formation. It has a very flat potentiometric surface and an average thickness of 45 m with confining beds above and below. The siliceous facies derives from weathering of the calcareous phase and is highly transmissive while the calcareous zone itself contains less water and is dependent upon interconnecting fractures for its permeability. Recharge appears to occur where the siliceous facies crops out around the edges of, and within, the Embayment. Aquifer management issues revolve around two points: successful dewatering of the orebody for mining; and efficient management to maintain water quality and ensure supply over the predicted 30-year life of the project. Current operations are extracting water at levels much below that originally estimated. This is having a detrimental effect on mine dewatering with the SWL lowering at a rate slower than anticipated. As a result, ore parcels are now beginning to intersect the water table, providing a major constraint to the mining plan. The aquifer drawdown cone is extensive and very flat so to keep the water table at an appropriate level for mining the management plan will include more aggressive dewatering to lower the level of the entire aquifer. The additional water will either be disposed of downstream or stored in a holding dam or via the use of artificial storage and recharge. Water resource management will also need to maintain the current quality. About 37 per cent of the water currently extracted forms the low chloride supply required by the ammonia plant and the power station. This ratio is expected to remain applicable under any future operating conditions but the low chloride resource is restricted so will require prudent management to enable the supply to continue. At current usage rates aquifer recharge versus use will need careful monitoring to ensure that the resource remains viable in the long-term.

Jan 1, 2003

By I Brunton

Blast fragmentation can have a significant impact on the profitability of a mine. An optimum run of mine (ROM) size distribution is required to maximise the performance of downstream processes. If this fragmentation size distribution can be modelled and controlled, the operation will have made a significant advancement towards improving its performance. Blast fragmentation modelling is an important step in Mine to MillTM optimisation. It allows the estimation of blast fragmentation distributions for a number of different rock mass, blast geometry, and explosive parameters. These distributions can then be modelled in downstream mining and milling processes to determine the optimum blast design. When a blast hole is detonated rock breakage occurs in two different stress regions û compressive and tensile. In the first region, compressive stress waves form a æcrushed zoneÆ directly adjacent to the blast hole. The second region, termed the æcracked zoneÆ, occurs outside the crush one. The widely used Kuz-Ram model does not recognise these two blast regions. In the Kuz-Ram model the mean fragment size from the blast is approximated and is then used to estimate the remaining size distribution. Experience has shown that this model predicts the coarse end reasonably accurately, but it can significantly underestimate the amount of fines generated. As part of the Australian Mineral Industries Research Association (AMIRA) P483A Mine to MillTM project, the Two-Component Model (TCM) and Crush Zone Model (CZM), developed by the Julius Kruttschnitt Mineral Research Centre (JKMRC), were compared and evaluated to measured ROM fragmentation distributions. An important criteria for this comparison was the variation of model results from measured ROM in the fine to intermediate section (1 mm to 100 mm) of the fragmentation curve. This region of the distribution is important for Mine to MillTM optimisation. The comparison of modelled and Split ROM fragmentation distributions has been conducted in harder ores (UCS greater than 80 MPa). Further work involves modelling softer ores. The comparisons will be continued with future site surveys to increase confidence in the comparison of the CZM and TCM to Split results. Stochastic fragmentation modelling will then be conducted to take into account variation of input parameters. A window of possible fragmentation distributions can be compared to those obtained by Split. Following this work, an improved fragmentation model will be developed in response to these findings.

Jan 1, 2001

Rock bolting and rock-bolting systems depend for success on attention to a number of simple techniques. Failure to appreciate this fact can lead to disappointing results. Careful study of rock characteristics and placement methods can allow a change to highly successful rock bolt per- formance. A number of examples are quoted to illustrate the sig- nificant improvement in results which can be achieved by use of the most suitable combination of characteristics.

Jan 1, 1971

By Khosia NK, Ravishankar SA, Sankar TAP

Alumina reduction in Rajhara iron ore slimes essentially involves separation of hematite from gibbsite in relatively coarser fraction and from kaolinite in the finer fraction. Selective dispersion flocculation studies on synthetic mixtures clearly indicated that while it was possible to achieve almost perfect separation of hematite from kaolinite using starch and PAMX (modified polyacrylamide containing hydroxamate functional groups) flocculants, no selectivity was observed in iron oxide-alumina system. A schematic flowsheet suggested on the basis of this work for the beneficiation of Indian ore slimes thus consists of classification in a hydrocyclone, followed by selective dispersion of coarse fraction (underflow) and selective flocculation of the overflow fraction. Starting with a feed assaying 46 per cent Fe and 11.6 per cent A1203, a concentrate assaying 60 per cent Fe and 4.7 per cent A1203 could be produced at an overall iron recovery of 60 per cent using conventional Reagents.

Jan 1, 1993