Search Documents

This paper reviews the current techniques employed in the prediction of subsidence and how they have been applied to partial extraction systems. The method using influence functions to describe the shape of the profile is investigated in detail and has been adopted to model the subsidence over workings in Huntly. It is compared with the profile methods developed in the United Kingdom and found to predict the subsidence profile more accurately than these methods.

Jan 1, 1991

The Ediacara mineral field is classified as a Mississippi Valley type deposit with stratiform mineralization near the base of the Cambrian beds. Mineral deposition was contemporaneous with sedmentation and reerystallization, and mobilization took place after lithification of the sediments. Several mechanisms of deposition were possible.INTRODUCTIONThe Ediacara mineral field is located in the Mt. James Range approximately 300 miles north of Adelaide, about 12 miles west of Beltana railway siding and 10 miles east of Lake Torrens. It is isolated geographically from similar deposits of equivalent age and environment in the Flinders Range Province (Fig. 1). The climate may be described as semi arid with high summer temperatures and frequent dust storms. Occasional thunder storms are the main source of rain in the summer months.The exact date of discovery is unknown, but is believed to be about middle of the last century. Ulrich (1872) was the first geologist to report on the field. At that time only the southern portion of the field had been prospected (and abandoned). Although the prospects did not appear encouraging Ulrich advised prospecting of the shales and testing beneath the limestone.In 1888, Rosewarne, an Inspector of Mines, visited the Southern Workings and queried whether they were connected with some lode at deeper level or were merely bedded deposits. The first geological map with sections was drawn by H.Y.L. Brown (Brown 1892).Brown recognized three principal rock formations as dolomitic sandstone, kaolinised shales and sandstone, and quartzites and sandstone in descending order. These three basic units are still recognized. He recognized also the stratiform nature of the mineralization in the shales as a...

Jan 1, 1963

By F Gervilla, J Laukkanen

The Kevitsa Ni-Cu-PGE deposit in northern Finland contains disseminated Ni-Cu-Fe sulfides, and platinum-group minerals (PGM). The 2.05 Ga-old ultramafic-mafic, funnel-shaped intrusion is intruded into a volcanosedimentary sequence. The major ore minerals are pentlandite, hexagonal pyrrhotite and troilite, chalcopyrite, cubanite and magnetite. Pyrrhotite and pentlandite are replaced by pyrite, millerite and heazelwoodite near the surface. Nickeline, maucherite and gersdorffite are locally abundant. A pilot feed sample of 575 t of the main orebody at Kevitsa had average grades 0.45 per cent Cu, 0.36 per cent Ni, 1.85 per cent S, 0.33 g/t Pt, 0.34 g/t Pd and 0.19 g/t Au, with 0.06 per cent Ni contained in silicates. Higher PGE contents (2 - 27 ppm) occur in a vertical N-S bearing fault zone. The PGM (n = 6022) mapped in specimens of four drill holes, consist of sperrylite 34.7 vol per cent, braggite and cooperite 18.5 vol per cent, geversite 17.2 vol per cent, moncheite 14.7 vol per cent, merenskyite 6.7 vol per cent, stibiopalladinite 4.3 vol per cent, sobolevskite 1.9 vol per cent, kotulskite 0.7 vol per cent, michenerite 0.6 vol per cent, keithconnite 0.3 vol per cent, rustenburgite 0.1 vol per cent, melonite, froodite, laurite together 0.1 vol per cent and only a few grains of sudburyite, irarsite, vysotskite, erlichmanite, hongishiite, Pt-Cu-alloys, three undefined Pd and Pt bismuthinides and antimonides and a Pd-Cu-bearing Pt-Ni-Fe sulfide. Most of the PGM, 62 per cent, are enclosed in silicates, 29 per cent are intergrown with sulfides, nine per cent are within sulfides. A portion of the PGE occurs in solid solution in sulfides and arsenides. Ni flotation yielded smelter-grade concentrates averaging 12.2 per cent nickel. The average sulfide Ni recovery is 78.8 per cent and total Ni recovery is 65.3 per cent. The average Pt is 10 g/t at 55 per cent recovery, Pd 7.7 g/t at 38 per cent recovery and Au 1.6 g/t at ten per cent recovery. Cu concentrates averaged 28.6 per cent Cu with an average recovery of 78 per cent and further 11 per cent in the nickel concentrate. The copper concentrate contains 4 g/t Au at 24 per cent recovery. The average Fe to MgO ratio 17.9 is well above the targeted minimum of 4.5. The pilot results show that the previously used TETA (triethylene tetramine) can be avoided and good quality, smelter-grade concentrates can be produced from the Kevitsa ore at economical levels of recovery by conventional flotation methods.

Jan 1, 2008

By D Craw

Bulk ore tailings from the Macraes gold mine gold extraction process are stored in a large (ca 0.6 km2, 80 m deep) mixed tailings impoundment whose pH is maintained near 8 by natural rock neutralizing capacity. The mixed tailings will be stored in this impoundment in perpetuity after mining ceases. Confidence in the long term environmental stability of these tailings can be gained from examination of mineralogically and chemically similar geological situations in the immediate vicinity. A sequence, typically about 5 m thick, of sands and gravels derived from the Macraes mineralized zone 12 000 to 28 000 years ago contains rounded detrital sulphide mineral grains which are unoxidized despite close proximity to the surface and occasional incursion of oxygenated waters. Saturating water pH is currently 7-8. Sands with 0.2 to 0.8 wt % organic carbon host sulphate-reducing bacteria (SRB), and localized cementation by authigenic framboidal pyrite has occurred. Comparison of the 28 000 year-old sediments with the modem tailings suggests that similar chemistry will prevail, possibly with deposition of authigenic pyrite in the tailings, in the long term. As long as the present slightly anoxic and circumneutral pH environmental conditions are maintained in the mixed tailings dam, sulphide decomposition and acidification are unlikely. These sediments provide a plausible geological analogue for long-term benign storage of the mixed tailings impoundment.

Jan 1, 2000

The observation of lower-than-predicted Fe/Cu ratios in the cementation of copper on iron in tests at elevated temperatures indicated that some other reaction was contributing to the reduction of cupric sulphate in addition to the reduction by elemental iron. Experiments showed that the copper sponge, which initially formed on the iron, subsequently reduced the cupric sulphate giving the products cuprous oxide and sulphuric acid.Tests were undertaken to determine the rate and equilibrium conditions of the reduction reaction with variations in the types of the reducing agent and solution parameters. The reaction first became apparent at temperatures above 50°C and as it ceased at pH 1·8 it was possible to induce further reaction by alkali addition.

Jan 1, 1974

The plant and processing site at Porgera has been built on a levelled mudstone ridge about lkm E of the mine. Excavation of 7xl06m3 of soil and rock was necessary to achieve the required area. The exposed mudstone belongs to the Chico Formation and is weak, sheared and readily breaks down by slaking upon exposure. Tectonic uplift and subsequent erosion have produced the present landscape of narrow bedrock ridges, with deep colluvium in the incised valleys. The deep excavation to a maximum of 60m, has rapidly unloaded the mudstone, and subsequent stress relief has caused rebound and dilation of the material. The processes of pore pressure equilibration, softening, progressive failure and loosening, combine to deteriorate the newly exposed rock mass. These processes are commonly associated with pre-existing shear surfaces, fissures and a

Jan 1, 1991

The published liquidus data on the Pb-PbS system have been correlated on the basis of one-coefficient Margules equations. Thermodynamic properties of the components of this system have been obtained, and it has also been found that the calculated miscibility gap of this system exists over a very narrow range of temperature (1041 to 1058°C).

Jan 1, 1972

By Patterson B. G

The small party of mining men who formed the original Mount Morgan Syndicate in 1882, commenced operations on the top of the mountain with what were practically nothing more than small hillside quarries, It was not until 1891 that underground stoping began, and open-cut mining therefore commenced with the commencement of operations. This hillside quarrying, however, seems to have been quite haphazard and unsystematic ; there is no trace or sign of any properly devised mining scheme. This can be seen plainly enough from an examination of old mine plans; for in less than five years after stoping was; adopted, the open-cut was down into the stoped-out ground. The following table, prepared from these old plans, shows the downward trend of the excavation in the past fiftyseven years:-

Jan 1, 1939

Residual aeolian placers (RAPs) are formed by the wind, by preferential entrainment and removal of small and low-density detritusfrom a pre-existing, typically sedimentary sequence containing heavy minerals. Heavy minerals that are resistant to chemical alteration and either soft and malleable (gold), or extremely hard (diamond, sapphire, ruby, etc), are concentrated as a residual on the wind deflation surface, typically in the interstices between larger resistant clasts. RAPs form preferentially in arid or semi arid areas, where the vegetation is sparse or absent, and where topography and surface gradients are low, but may also form on beaches and in periglacial environments. RAPs consist of a continuous or discontinuous, planar or gently undulating horizon of heavy minerals in a single-clast-thick pavement of resistant pebbles, cobbles, or boulders, which mantles the present topography or palaeo-topography. Extreme wind erosion and surface deflation may condense the full pre-existing sequence into a layer of heavy minerals only. The grade of RAPs is substantially higher than in the precursor deposit, and commonly much higher than those typically found in most other placer types. Aside from their general occurrence as a thin pavement of resistant clasts, the best indicators of residual aeolian gold placers are the presence of wind-eroded stones (ventifacts) on the pavement, and the distinctive and unique shapes of aeolian gold grains themselves. The shape of the gold grains is progressively transformed by sand blasting during placer development, from grains with thickened rims, to toroidal grains on which the rims are æsplitÆ and peened inward toward the grain centre on one or both of the grain sides, to hemispherical or sub-spherical grains that are fully encapsulated by the in-turned rims. Gold that has undergone aeolian shape transformation is difficult to entrain and transport away from the site of aeolian concentration by anything other than mass movement or glacial processes. It is also easily retained by commercial recovery plants of any configuration.

Jan 1, 2004

Using Positron Emission Particle Tracking (PEPT) to Investigate Industrial Systems

Sep 13, 2010

On-stream determination of xanthate concentrations can be made by photometric measurements at 313 nm.A simple double-beam instrument was developed for this purpose. A mercury lamp is used as the light source and a composite filter of UGll glass and chromate solution is used to isolate the required spectral region. The light beam is split into two components of approximately equal intensity. One component is passed through a reference cell containing water to a photo detector; the other component is passed through the xanthate solution to a second photo detector. The reference signal controls amplifier gain to eliminate effects of lamp intensity changes and the amplified sample signal can then be used to measure xanthate concentration.Plant trials showed that provided a clear solution free of air bubbles was obtained from an on-stream filter, the instrument indicated the xanthate concentration and operated satisfactorily for long periods.

Jan 1, 1973

GENTLEMEN, lt is with much pleasure I meet you tonight at this the second meeting of the Australasian Institute of Mining Engineers, held in Western Australia, and I sincerely thank you for the honour you have conferred upon me in electing me as your President. I greatly appreciate the distinction, and will endeavour to fulfil the duties of the office to the best of my ability, and hope to prove a worthy successor to those gentlemen who have held the position before me. On behalf of the local members of the Institute, I extend a hearty welcome to the members from the other States of the Commonwealth, who have come so far to attend this meeting, and also to the non-members whom we have invited this evening. We are especially pleased to have Mr. Gregory, our Minister of Mines and Railways, and the Government and School of Mines officials with us; and I take this opportunity to thank the Premier, Mr. Gregory, and the Government officials for the assistance given us, and for doing so much to make the visit of our members from the other States so pleasant and instructive. I have also to thank the Mayor and Councillors of Kalgoorlie for the courtesy and hospitality given to our members, which is much appreciated.I assume you want me to follow the time-honoured custom of giving a Presidential address...

Jan 1, 1909

IN all wet concentration processes it is of primary importance to determine to what degree the crushing must be carried in order to obtain the maximum profit per ton of ore milled.To effect a clean separation, either by gravity or flotation treatment, between either one valuable sulphide from another, or a sUlphide from the gangue, the ore must have been subjected to grinding to such an extent that the particles to be separated are completely liberated from each other.Insufficient crushing will result in either an incomplete separation of the sulphides from each other, and thus a loss of the one sulphide in the other, or else a loss of the valuable sulphide in the gangue.This being so, the question arises whether the added cost of extra crushing would be economically warranted by the increased recovery consequent on such a step.

Jan 1, 1927

By N Phillips

Fosterville gold mine recently celebrated production of its one millionth ounce of gold based firmly within a history of refractory sulfide gold mining. Compared with other Victorian gold mines, the disseminated nature of the sulfide gold is a deposit style with low estimation variance combined with established processes to accurately delineate the controlling structures. The systems in place had been established and have worked effectively for the majority of the one million produced ounces.By the end of 2014, diamond drill campaigns targeting the lower Phoenix orebody at depths of 800 m below surface began showing a change to the nature of the gold within the deposit. Coarse visible gold within 0.5–2 m thick quartz carbonate veins were being intersected with regularity showing the emergence of a different zone of gold mineralisation.Data about the new and exciting discovery couldn’t be gathered fast enough, however, established systems and processes throughout the geology and processing departments were not developed to handle a coarse gold environment. Change would be commensurate with the size and scale of the discovery, and new learnings would need to be implemented quickly to keep in front of a mining schedule that was focused on producing tonnes due to the dropping grades of the sulfide ore.Gold assays being returned were showing that the gold nature was different to those of other Victorian deposits. Comparative to the highly nuggety nature of gold found in other Victorian goldfields, the fine grained gold accumulations were dispersed in relatively consistent narrow linear trends grading consistently into the hundreds of grams per tonne. New drill intersections were being returned by the day and research to find developed orebodies that had published information into how to handle such a rapid change yielded few examples.The challenge was to review and set new standards with regards to handling an orebody that transitioned the very nature of the gold being mined. This involved reviewing all steps in the estimation process including data capture and quality control and quality assurance through to mineral liberation through the mill. Difficulties also involved finding analogous orebodies that consisted of both free milling and refractory ores that were dealing with drill assays that were measured as percentages of gold.CITATION:Phillips, N, 2017. Fosterville gold mine – breaking the mould for Victorian gold, in Proceedings Tenth International Mining Geology Conference 2017, pp 393–400 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 20, 2017

CONTENTS:1. Introduct'iona. Previous Accountsb. Summary of Geologyc. Physiography2. Morgan Groupa. Lithologyb. Structurec. Faulting3. The Mineral Deposita. Descriptioni. Size and Shapeii. Compositioniii. Effects of Oxidationb. Relationship to Structurec. Genesis of Ored. Mount Morgan Orebodye. Sugarloaf Orebody4. Granitea. Mount Morgan Graniteb. Town Granite'c. Moonmera Granite5. Calliungal Beds6. Razorback Beds7. Acknowledgments8. References

Jan 1, 1952

By Xu Z, Hu C

An attempt has been made to investigate the performance of green pellet formation of the Daye magnetite concentrate from the weak-magnetic separation plant. The optimum conditions for the commercial production of green pellets was found through experimental research. The satisfactory size range for balling is 75 ¦ 3 per cent -200 mesh. The suitable moisture content is between 8.7 and 9.1 per cent and the optimum amount of bentonite added is between 1.5 and 2.5 per cent. The emphasis is on the size of the feed materials since the grinding fineness, which can be obtained at the plant, at most is 78 per cent -200 mesh. If the optimum fineness for the pellet formation is above this value, this means that the concentrate must be re-ground before balling. The results from experiments showed that a good quality green pellet can be attained by using materials below 78 per cent -200 mesh, which provides a strong foundation for the commercial production of green pellets.

Jan 1, 1999

The large increase in secondary industries in this country, during the war and post war periods, has caused a shortage of capacity for the production of merchant bar.To overcome this shortage, an expansion of rolling mill facilities has been undertaken by the Broken Hill Pty. Co. Ltd. A small, but modern, merchant mill has been erected at Kwinana in Western Australia and a strip and skelp mill is under construction at Newcastle. The latter mill will roll strip and skelp at present being rolled by the Newcastle 10 in. Merchant Mill, enahling this mill to concentrate on merchant bar production.The Kwinana mill was installed to supply the Western Australian market. This state has a small population (approximately 658,000) and is not at present highly industrialised. It was necessary, therefore, to design a mill which would be capable of producing a wide diversity of sections and could be expanded as the demand increased. To begin with capital expenditure had to be kept within reasonable bounds. The design work for this mill, with the exception of a few specialised items of equipment, was carried out at Newcastle.All design work for the Newcastle mill was carried out by the lVIorgan Construction Co. of America. Although initially intended for rolling flat. products, the designers were asked to make the mill as flexible as possible, so that should the market for flat products decrease, this mill with additional equipment could undertake the rolling of medium sized sections.

Jan 1, 1957

Australia is the world's leading producer and exporter of mineral sands. Despite increased production from some other countries in recent years, Australia maintained its No.1 position in 1988 among world producers of mineral sands concentrates. Production of the titanium minerals -- ruffle, ilmenite and leucoxene, as well as synthetic ruffle -- by the seven companies currently comprising the Australian industry increased in 1988 in response to continuing strong demand for feedstock by the pigment industry. Production of co-product zircon remained at the 1987 level, reflecting declining zircon grades. Exports of mineral sands concentrates increased in 1988; export earnings exceeded $300million. Prices for mineral sands concentrates are now at a historical high and, assuming that the world economy remains strong, real prices should continue to trend upwards in the short term. Exploration in the Eneabba-Cooljarloo region and the Scott River area, both in WA, the Murray Basin, Vic, and the central Queensland coast area, has identified substantial resources of heavy mineral sands. These discoveries have reversed the trend of the early 1980s of falling resources of mineral sands. In 1988, BMR estimated that economic demonstrated resources (EDR) of ilmenite, rutile, zircon and monazite combined was about 72.8 million tonnes. However, a substantial portion of the resources on the east coast are frozen as a result of environmental considerations. The proportion of mineral sands concentrates processed in Australia increased with the commissioning of two new synthetic rutile plants; Australia is now the world's leading producer of synthetic rutile (total capacity 272000 tonnes), most of it for export. Australia's two TiO2 pigment producers have both increased capacity, lifting national capacity by some 70p ercent to over 120000 tonnes/yr. As part of the expansion one producer converted from the sulphate to the chloride process. Other new pigment plants are being proposed for the future.

Jan 1, 1989

By Hargraves A. J

The paper outlines events at the Collinsville State Coal Mine, Queensland, leading to the practice of full face multiple shotfiring in bord and pillar development places. The 1954 disaster is referred to, and factors involved in simultaneous shotfiring in coal are discussed. Promising preliminary multiple shotfiring tests at the Colliery are described, as well as the resulting routine measures adopted, and the changes involved. The subsequent inducing of two outbursts under safe conditions by remote multiple shotfiring is given as justification for the changes made.INTRODUCTIONFollowing a disastrous instantaneous outburst (1.0.) of coal and gas at the Collinsville State Coal Mine in 1954, the necessity for inducer shotfiring for the control of possible further outbursts was established. However this mine, immediately classified as gassy after the 1954 outburst, is subject to the general restrictions pertaining to gassy mines which at present preclude the use of inducer shotfiring due particularly to the non-existence of a permitted exploder for more than six shots, and further, because permitted multipleexploders are not designed for remote firing through long lengths of cable. This situation was met by arresting or reducing progress in the production places, thereby reducing the danger of outbursts while means were being considered to achieve overall maximum safety.In August 1957 two full faces were successfully blasted in experimental simultaneous rounds. In June 1958 four full faces were blasted, and in October 1958 full face grunching without prior cutting, Le. inducer shotfiring, was introduced in No. 1 Tunnel as a production feature. In March 1960 it...

Jan 1, 1960

By D Brett

"Mine waste storages including tailings dams and waste rock dumps represent arguably the biggest risk on a mine site from both physical and geochemical viewpoints, related firstly to structural stability and the consequences of failure and secondly from potential on-going seepage or run-off of acid and metalliferous drainage (AMD). The risks are most likely to increase during operations and continue through the closure and post-closure phases, with the waste storages likely to be the most difficult features to resolve in the mine closure process. Contaminated water quality from tailings dams and waste rock dumps can require treatment "in perpetuity" at a cost of hundreds of millions of dollars. The problem is increasing with ever larger mine operations and waste generation volumes. This paper identifies leading practice methodologies in planning and operating mines and process plants to minimise the risks from tailings storages and how this might also affect waste rock management and even the design of mine excavations. These methodologies require a "big-picture" approach to develop an understanding of the overall issues and identify synergies between the different operational areas on a mine site that can reduce overall risk. With a conservative approach and realistic allowance for future costs it is possible to facilitate decisions at the mine planning stage that can reduce risk and save cost over the long term. This is in contrast to the common approach where each operational area is looking to minimise its own costs with a short-term view. Incorrect mine methodologies can be developed by allowing net present value (NPV) accounting methods to trivialise future closure issues.Methodologies discussed include: Integrated Waste Management - Significant structural improvements to tailings dams can be achieved if the structures can be incorporated into the waste rock dumps. Risk of AMD can also be reduced by utilising the tailings and waste rock effectively. This could go even further to consider the placement of wastes to limit mine void environmental issues; Process Optimisation - Water quality and the nature of potential tailings dam structures can be highly influenced by the geo-chemistry of the tailings. This can be modified by processing, where simple changes such as maintaining separate streams of geo-chemically different tailings rather than recombining them or by initiating further processing to remove problematic minerals such as sulphides; Enhancing Geophysical Properties - The geochemical performance of waste repositories can be greatly influenced by the geophysical properties of the stored materials, particularly the air-water characteristics, which are influenced by particle size, density and permeability. The geotechnical properties can be enhanced by strategic paddock dumping, blending and compaction.These methodologies are demonstrated by case histories.CITATION:Brett, D, 2013. Mine waste risk minimisation by integrated waste management and process optimisation, in Proceedings MetPlant 2013, pp 247-258 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jul 15, 2013