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By P Trotta

The paper provides a structured methodology to investigate metallurgical problems within the operating concentrators. The strategy uses classical metallurgical data analysis as well as pulp, solution and surface analysis to determine the reasons for particular behaviours. The approach applies equally to all mineral-processing operations. To demonstrate its effectiveness a case study, based on work conducted at Pasminco Rosebery Mine, is described. In this work, the classical metallurgical analysis indicated that a significant amount of sphalerite reporting to the lead concentrate occurred as liberated particles. A combination of pulp, solution and surface analysis supported the hypothesis that the liberated sphalerite was recovered by inadvertent activation by lead ions. Laboratory studies have indicated that the use of sodium carbonate, by itself and in combination with zinc sulphate and sodium cyanide, when added to the lead regrinding mill can depress sphalerite flotation, resulting in an improvement in the lead grade/recovery curve. When this approach was tested in the plant other more dominant issues masked any positive effect the addition of sodium carbonate may have had. The plant trial highlighted the real need for additional regrinding capacity.

Jan 1, 2002

Alaska Native corporations, as representatives of the aboriginal inhabitants of Alaska, control the mineral rights to 18 million hectares of Alaska, approximately 12% of the state. These corporations were established through legislation passed by the United States Congress in 1971 designed to settle the land claims of the Native peoples of Alaska. Twelve corporations, each representative of a specific geographic and cultural region, were established and granted the mineral rights to most Native lands in their respective regions. Since that time the Native corporations have taken an active role in mineral development in the state. Generally through agreements with established mining companies, Native corporations encourage balanced exploration and development of their lands. Substantial mineral potential has been recognized on Native corporation land, which includes holdings in many historic mining districts of Alaska. Several world class deposits have been discovered on Native corporation land, including the Red Dog zinc-lead deposit, which began production in late 1989. The experience of Alaska Native corporations demonstrates that aboriginal peoples can be very positive forces in resource development.Alaska, although remotely located in the Northeast corner of the Pacific Basin, is playing an increasing role as a supplier of natural resources to the region and the world. Most of Alaska's privately held natural resources are owned by the aboriginal inhabitants of the state. These aboriginal inhabitants, now collectively referred to as Alaska Natives, have emerged in the last two decades as having a major international impact in mineral resource exploration, development, and production.

Jan 1, 1990

Cyanidation tests by bottle agitation were conducted on an oxidized lead-silver ore containing approximately 12% Pb and 500 g/t Ag. Over 60% of the silver was leached when the ore was ground to 100% passing 0.15mm, whereas 50-60% of the silver was leached when the ore was only ground to 100% passing 0.5mm. Slurry handling and dewatering at the fine grind size were very difficult due to the high clay content of the ore, however this problem was greatly reduced at the coar- ser grind size. The silver recovery at the fine grind size was very dependent on cyanide solution strength with stronger cyanide sol- utions (containing more than 0.1% NaCN) re- sulting in lower solution silver contents. This was thought to be due to the precipi- tation of leached silver by zinc, which was also leached from the ore by the higher cyanide levels. There was a critical zinc level in solution of approximately 1000ppm, above which the silver recovery fell markedly. Cyanide and lime consumptions for this ore were high (typically 5 kg/t and 40 kg/t respectively), hence the processing of this particular ore by cyanide leaching is un- economic at current silver prices.

Jan 1, 1987

By McLeod RL

The Mt. Morgan mine, located 36 km SSW of Rockhampton, Qld at Lat. 23¦38' S, Long. 1500 22'E, is hosted by a Middle Devonian sequence of acid volcanic rocks and sediments. The Upper Nine Mile Creek (UNMC) prospect, 14 km SE of the Mt. Morgan mine, is in an ap- parently equivalent sequence of rocks. The Late Devonian Mt. Morgan Tonalite separates the two areas. The Mt. Chalmers mine, located 27 km NE of Rockhampton at Lat. 23¦ 18' S, Long. 150039'E, is hosted by the Early Permian Berserker Beds. These three volcanogenic massive sulphide deposits show pronounced similarities in their host rock lithologies and stratigraphic-struc- tural settings.

Jan 1, 1987

By Craw D

The Southern Alps in the South Island of New Zealand are currently rising rapidly as a consequence of continental collision along the Pacific-Australian plate boundary. Rapid uplift has resulted in a major thermal anomaly in the shallow crust beneath the alps. Alpine topography and associated intense precipitation, coupled with the thermal anomaly are responsible for vigorous combined topographic/convective circulation of water through the shallow crust.

Jan 1, 1995

By Miskelly N

In Australia and New Zealand, the 'Australasian Code for Reporting of Identified Mineral Resources and Ore Reserves', which was released by industry in 1989, is operating successfully in a co-operative approach between industry and regulatory authorities. Similar codes or guidelines exist or are under development in the United States of America, Canada, the United Kingdom and South Africa, although the regulatory backing given to the Australasian Code is unique. International standard definitions for Mineral Resources and Reserves, and for categories of Resources and Reserves, have been under development by the Council of Mining and Metallurgical Institutions since 1994 and have already stimulated considerable convergence of definitions and reporting standards in participating countries. It is hoped that agreement on this international standard for public reporting by mining companies will be reached within the next two years, and it is expected that adoption of the standard will result in a higher and more uniform quality of reporting worldwide, with a consequently greater interest on the part of the general public and financiers in investing in the mining industry.

Jan 1, 1997

By McCarthy J

In both the U.S.A. and Canada regulations concerning the reporting on mineral resources and especially ore reserves have been established. The regulations are virtually identical for the two countries with the main exceptions being who is franchised to write the report and how the various reserve categories may be used in reports to the public. Both countries divide ore reserves into "proven", "probable" and "inferred" categories. "Proven" reserves are those for material for which tonnage is computed from dimensions revealed in outcrops, trenches, underground workings or drill holes and for which the grade is composed from the results of adequate sampling. "Probable" reserves are those which are less well defined than "proven" while "inferred" reserves are generally those which may exist through geological and geophysical interpretation. The AusIMM/AMIC draft guidelines as proposed for use in Australia define more rigidly the ore reserve categories into "proved" and "probable" terms, which can only be applied following a full and favourable analysis of economic, mining, metallurgical, marketing and sociopolitical factors. If the ore reserves are not supported by this analysis they are placed into a "resource" category. Proper application of this proposed Australian model could prove useful when dealing with grass-root prospects or mining properties in the pre-feasibility stage. Combined with competent reporting, use of the proposed guidelines should ensure standardised and more verifiable analysis/valuation of a company's mineral assets.

Jan 1, 1987

By A Lim

"As Abel Mine continues to expand and increase production, the requirements of the ventilationsystem have also increased. This paper will outline the stages undertaken to increase the AbelMine ventilation system from an operating position of 110 m3/s and 500 Pa to the current operating position of 220 m3/s and 1.6 kPa and outline steps to be taken to ensure all future requirements will be able to be ventilated."

Jun 1, 2012

The torsion test is considered as the best test used when the part is subjected to static or dynamic torque. Many published papers have investigated the torsion of non-heat treated metals. However, very few published papers dealt with the torsion behaviour of heat treated metals. The aim of this work was to study the effect of heat treatment on the torsion behaviour of steel alloy (AISI 01), which can be used for manufacturing small and medium drills, taps and reamers. The diameter of specimens used was 15 mm. The metal used was heat treated under different conditions, then torsionally tested. The results of torsion test were divided into two groups: results obtained during elastic limit from which the shear stress, shear strain and modulus of rigidity were calculated, while from the results obtained during plastic limit the plastic depth was calculated by applying derived equation when the angle of twist was more than yield value. The results obtained indicated that the value of hardness alone is not sufficient to establish heat treatment conditions. Rather, it was found that the determination of plastic depth together with hardness can help in the establishing of the optimum condition which was hardening temperature of 820¦C, hardening time 20 minutes and tempering temperature 220¦C. This condition produces hardness of 60 HRc and plastic depth of 2.5 mm.

Jan 1, 2003

By L C. Thompson

BioLix is the term for a new class of biologically-derived lixiviants for precious metals (gold and silver) recovery. BioLix can be used as an alternative to cyanide on virgin and spent ores. The BioLix process is based on inducing microbial enzymatic reactions that generate organo-lixiviant chemicals. The bioprocess involves a two-stage culture strategy. First, specialty microorganisms are cultured to generate a high biomass. Then, a food-grade quality amendment is introduced that forces the microorganisms to produce the organo-lixiviant. The second-stage culture is applied to the ore where the microbial/lixiviant system acts on mineral surfaces to extract precious metals. The process operates at ambient temperatures and near neutral pH. This paper will examine the BioLix process through an extensive laboratory development and demonstration project. Laboratory development consisted of identifying and isolating specialty microorganisms and inducing agents for the production of the organo-lixiviant solutions. A demonstration was performed on low-grade and high-grade oxidised ore from the Buffalo Valley mine in Nevada, USA. Results indicate that the BioLix process was comparable to cyanide in terms of gold recovery and operated at near neutral pH and ambient temperatures. Applications for the BioLix process will be discussed including spent-ore re-leaching, cyanide replacement for virgin ore, and in situ mining.

Jan 1, 2004

By Baynes F. J, Bermingham A. G

The 6000m long King Headrace Tunnel will be driven through hard Owen Conglomerate in the Eastern third and feldspar porphyry in the Western two thirds, with the anticipated hardness up to 350MPa unconfined compressive strength. Since the Commission had not driven a long, large diameter tunnel for some twenty years, major research was undertaken to assess the current tunnelling trends. Tunnel boring machines were compared with drill and fire equipment. Rail equipment was compared with rubber tyred equipment. Tenders were called with tenderers invited to submit alternatives if desired. Commissioning and production excavation using the equipment is discussed with the final conclusion being that the individual items of equipment purchased combined to make an efficient hard rock drill and blast system capable of progressing through all rock conditions likely to be encountered on the King and Anthony Schemes.

Jan 1, 1987

By Weller KR

Completely dry or completely wet materials are comparatively easy to screen, but materials with moisture contents between these two extremes can present varying degrees of difficulty. The presence of moisture can impair the performance of a dry screening plant in a number of ways: ò agglomeration of fine undersize particles onto larger oversize particles, resulting in the fine particles being misplaced to the oversize; ò increasing attractive forces between particles that hinder stratification and particle presentation to the screen; and ò blinding of the screen apertures caused by fine moist particles clinging to the screen which reduces the effective aperture size and the open area of the screen. Test work on full-scale screens has shown that the agglomeration of fine particles onto larger particles only occurs once the equilibrium moisture content of the ore is exceeded, and that the quantity of adhering fines present is proportional to the surface area of the larger particles. An -adhering fines screen model has been developed from this work, and by using relationships derived between the model parameters and feed moisture content, the effect of changes in feed moisture on both product quality and operation of iron ore dry screening plants is predicted.

Jan 1, 1993

ALTHOUGH the mineral Stannite (Cu2S, FeS, SnS2 , also known as "bell 'metal" ore, tin pyrites, etc.) is found in various parts of the world, in only three iocalities has development proved it to exist in sufficient quantity to warrant the erection of treatment plants. Two of those mines are in New South Wales and one is an Tasmania. The writer will deal with the latter-the Conah mine, Zeehan, Tasmania, it being the most important and extensive occurrence so far worked. The Conah mine was first worked by a Tasmanian company for silver-Iead, and was fairly remunerative until the zone of secondary enrichment was passed through, when the lodes became too poor for further exploitation. During the time that the line was thus operated the stannite lode was discovered. It occurs in a graphitic slate, which, in common with the slates and spilites of the Zeehan field, is probably underlain by the stanniferous granite which outcrops two miles to the west. The Conah stannite lode is older than the galena lodes of the district, being faulted by one of the latter. Near the surface the lode was very rich.Shipments were sent out assaying 150 oz. of silver per ton, 20% copper, and 18% tin. An .apparently homogeneous sample of stannite, analyzed by the writer for the Tasmanian Geological survey, gave the following results:

Jan 1, 1915

By Neville WE, Parkinson J

One of the earliest recorded risk management schemes was implemented by the boatmen of the Yangtze river some 4,000 years ago.. Between them they arranged for shipments to be split up in such a way that a load was divided five ways: if one was lost, then 80% of the shipment got through. Bottomry contracts were in vogue in Babylonian times with similar systems being used in India, in 60OBC and 4th century Greece. One of the first accepted mutual insurance ideas came in 1835 when a mill owner in America negotiated a lower insurance premium in return for installed fire safety measures. Approximately 20 years ago risk management as a philosophy was developed in the U.S.A., the philosophy followed to England and hence to Australia about 10 years ago. The business climate which induced the philosophy of risk management was that of "tight money". The definition of "assets" was then broadened to include earning capacity, skilled personnel and in a negative sense, a corporation's liabilities. In more affluent days losses were comfortably absorbed into the ongoing business expenses, the more prudent managers took out insurance which "covered everything" at a suitable premium. Statistics are available to indicate that a high percentage, (over 60%) of businesses which suffer massive plant damage due to fire, do not restart operations, or in the event of restarting have closed operations within the next 2 to 3 years - in spite of collecting an insurance payout.

Jan 1, 1986

In 1965, Peter Flawn author of the famous text-book on Mineral Resources (1966) published a paper in Economic Geology with the delightful title `Who took the `Economic' out of Economic Geology?'. He opened this most interesting article with the following paragraph:If one were called upon to cite an example of a fish out-of-water he could hardly pick a better one than a recent graduate of geology of an America university who is suddenly faced with the responsibility of evaluating or appraising a mineral property. And I venture to say that the 'ftsh' with a doctorate - even in economic geology - is not much better equipped than one holding a lesser degree. The new graduate with a major in economic geology probably knows the significance of the various sulphur isotopes, he surely knows a great deal about the chemistry of the ore forming fluids and he recites with ease the arguments which prove deposits are epigenetic rather than syngenetic. However he is a rare bird indeed if he knows anything about the economics of the mineral industry. The truth is that geologists who are engaged in evaluation work are largely self taught. I ask my more distinguished and experienced colleagues - `Has it always been this way? Who took the `economic' out of economic geology?

Jan 1, 1993

By Nettle W. H V

THE past few years have seen a considerable expansion of the roasting of blende in Australia. The bulk of this blende is Zinciferous concentrate from Broken Hill and now forms a very considerable source of sulphur for the acid manufacture. It will bereadily conceded that Australian sentiment is in favour of utilising all known potential wealth, especially that won from below ground, as this once disposed of is gone forever. If Australia does not make sulphuric acid from her sulphide ores we may be sure that the purchaser of these ores will do so if in any way possible. It must not be assumed, then, that the difficulties met are mentioned with the idea of undue criticism, but rather to show that, although most of the intial troubles have been overcome, there are still a few to be encountered; and with the hope that comment brought forth will aid in the solution of the problems facing an industry at present little more than in its childhood as far as Australia is concerned.Blende roasting is done in mechanical furnaces of various makes, and mostly without the aid of other fuel than the sulphur in the ore. It will be our aim to touch on the various difficulties in the order in which they occur in the train from furnace to acid plant.

Jan 1, 1926

By J E. Eberhardt

Ore sorting has long been used to raise the efficiency and thus lower the environmental impact of mineral processing operations. It was first instituted as hand sorting, according to a humanly perceived difference in the ore, but is now automated using large mechanical sorters in order to meet the high tonnage throughput required in most minerals processing applications. In the past, ore sorting was generally used as a niche processing route when other approaches failed, and in this context, consequential environmental benefits are often not the first consideration in adopting sorting. When applicable, ore sorting offers environmental benefits in reductions in fines waste, reagent usage and energy consumption in milling. Although there are significant opportunities for the use of ore sorting technology in many minerals processing operations, industry applications, to date, have been limited mainly to the processing of diamonds, magnesite, talc and uranium ores. This limitation has principally been due to a lack of suitable sensing technologies for a wide range of ore types. The authors report on a wide-ranging review of the automated sorting of mineral ores, and in particular, on methods for discrimination of ore characteristics prior to mechanical sorting.

Jan 1, 2002

By S E. Box, J L. Mauk

The Middle Proterozoic metasedimentary rocks of the Belt Supergroup contain important metallic mineral deposits like the diagenetic sediment-hosted stratiform copper mineralization, including the Troy (Spar Lake) deposit and the epigenetic hydrothermal veins in the lower Belt and Ravalli Group in the Coeur d'Alene district. Magnetite (Fe3O4) is a common and widespread accessory mineral in these rocks and can have multiple origins including ore stage in deposits, mobilization stage in source rocks, metamorphism of red beds and alteration mineral in thin halos enveloping Ag-rich veins in the Coeur dÆAlene district. As shown in several classic studies, the composition of magnetite from igneous rocks varies significantly in response to controlling factors such as melt composition, temperature, silica activity, and oxygen and sulphur fugacity. Therefore, the distinctively different geologic settings within the Belt Supergroup strongly suggest that there may be differences in the magnetite compositions. However, initial microprobe analyses detected no variation in magnetite composition.   Three possibilities may give an adequate explanation for these initial results: 1.      the magnetite formed primarily as pure Fe3O4, 2.      one or more tectonothermal events led to regional scale re-equilibration that affected all rocks in the field area, and 3.      the variations in the composition are below the detection limit of the microprobe.

Jan 1, 2007

By Peng SS

This paper presents a number of mathematical models for predicting the different phases of the complete surface subsidence process associated with underground longwall mining. A computer program developed based on the mathematical models is briefly introduced.

Jan 1, 1992

Conditional simulation is a branch of geo- statistics which allows the simulation of a mineral deposit so that predictions can be made about the variability of some particular parameter of the deposit. A summary of the general principles, advantages and limitations of conditional simulation is presented together with an example based on coal seam thickness.

Jan 1, 1981