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By Richards S. M

The abundances and abundance relationships of lead, zinc, copper and silver in the major sulphide lenses at Broken Hill are examined, and their possible geochemical significance discussed.When expressed as atoms per cent, zinc is the most abundant base metal throughout the whole .group of orebodies, the highest average lead: zinc ratio (No. 2 lens) being about 0·45, the lowest (No. 1 lensZinc Lode group) being in the 0·12-0 ·14 range. Lead and silver are clearly higher in the lower two orebodies, but the abundance of zinc shows no apparent relationship with stratigraphical position. Among the base metals copper is conspicuously low and remarkably uniform, a feature noted in other conformable orebodies.Although, as has been recognised for many years, abundances of silver and lead, and lead and zinc, are sympathetically related, correlation within the pairs is variable and generally of low degree. Silver and lead show distinctly the better correlation, particularly in No. 3 lens. On the basis of lead: zinc ratios, No. 2' and No. 3· lenses, on the one hand, and the No. 1 lenses, Rhodonitic and Siliceous Zinc Lodes on the other, constitute two groups. However on the basis of silver : lead ratios, No. 3 lens stands alone, No. 2 lens showing clear affinities with the higher layers. Ternary relationships between copper-zinc-Iead and silver-zinc-Iead emphasize the very close constitutional relationship between the No. 1 lenses and the two "zinc lodes".The possible implications of these relationships are then discussed in the light of the' two principal theories-hydrothermal replacement or chemical sedimentation-held for the formation of the Broken Hill ores. It is pointed out that the ratios of the four metals in the ores are rather different from those found in most igneous and sedimentary rocks, and in seawater. For 'example, whereas copper and zinc are present in almost equal amounts in most terrestrial materials, copper in the ores is only about one-hundredth of the amount of zinc. Lead has increased somewhat, but the ratio of silver to lead has fallen; in spite of its recognition as a source of silver, the Broken Hill lode is impoverished in silver with respect to lead as compared with most common terrestrial materials.No solutions are offered to these prob'lems of abundance. Rather it has been the aim of the work to provide data, and to demonstrate the...

Jan 1, 1961

An oxide ore heap (80,000 ton assaying 2 per cent copper) and a sulphide ore heap (300,000 ton assaying 1·7 per cent copper) are being leached in series in a closed circuit system. The ore is friable and weatherseasily giving severe percolation problems. These were eased by applying liquors at 235 gal/min to trenches 2 ft wide and 6 ft deep along the full length of the heaps.Cementation recovery was improved from 20 per cent to over 80 per cent by regular intermittent agitation of the iron using a back hoe unit.Liquor pH is controlled by acid addition, and iron content is controlled by a bleed-off set according to predictions made from a pH-Eh diagram drawn for the liquor components. These controls, together with acyclic wetting and draining procedure, have raised production from 6 ton/week to 10 tdn/week of 80 per cent copper.

Jan 1, 1968

By M J. Kongas, K M. Saloheimo

This paper presents the art of on-stream particle size and elemental analysis used at iron ore concentrators, followed by the results and experiences from several sites.Online particle size analysis is rather common at medium- to large-sized concentrators. Online X-ray fluorescence (XRF) elemental analysis, however, is only used in some iron ore concentrators, while it is a routine practice in base metal concentrator plants. Online XRF analysis is applicable for process monitoring and control down to four to five per cent silica by measuring Fe assays accurately. With lower silica content, direct measurement of silica and other light elements is required. Some light element analysers that are based on the prompt gamma neutron activation analysis (PGNAA) method have been developed, but they have not performed up to expectations with slurry analysis. Other methods have been tried though these have not been used beyond prototype installations. Operating online light element slurry analyser installations are not common in iron ore applications.There is an economic incentive to mine lower and variable grade iron ore resources, which require concentration and removal of several impurities to produce high-quality concentrates for pellet production. Monitoring such operations by on-stream analysis has significant economic benefits, and there is a need to develop a dependable slurry online analyser for Si, Al, Mg and other light elements. The latest developments in slurry on-stream light element analysis are described.CITATION:Kongas, M J and Saloheimo, K M, 2013. Online slurry analysis for process control and monitoring at iron ore concentrators, in Proceedings Iron Ore 2013 , pp 303-308 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 12, 2013

By B S. Utting, W J. Cowie

The alluvial gold industry of New Zealand is based on the placer deposits in Otago and on the West Coast. Production from these since discovery in the 1850s has been an estimated 480 t (15 Moz) of gold. Annual output has expanded continuously since 1980 and is expected to be over 2 t of gold for 1989. Following a historical review, the characteristics of typical operations, which use hydraulic excavators and mobile trommel units are discussed. Descriptions are then given of alluvial activities in Otago and on the West Coast.

Jan 1, 1990

Strategic planning in mining is an important value accretive process. One of the most important aspects during the planning phase is determining the correct mine and plant design. The traditional mine site design (mine, plant, stockpiles, dumps) develops a fixed system for one set of conditions or expected values. A robust design is a fixed system that is designed to deal with a large range of conditions without changing the system design. A flexible design changes the system dynamically in response to changes in uncertainties. It is hypothesised that a robust design generates less value than a flexible design as it fails to realise the value of actively managing the operation. One of the most critical aspects in creating strategic value from a project is embedded in the design of the system. A flexible design has components that allow the design of the system to change over time. An operational plan is proposed as a hybrid of a robust and flexible design. This paper seeks to compare these different design methodologies. An analysis of the same case study is undertaken to compare these approaches, showing an a traditional net present value (NPV) of $1678 M, robust design NPV of $1787 M and an operational plan NPV of $1867 M - an increase of $170 M.

Dec 6, 2010

By D A. McCallum

With depth, many gold ores become sulfidic with minerals such as pyrite, pyrrhotite and arsenopyrite becoming prevalent. In addition, many underground gold mines use tailings backfill to bind and store the waste. In these cases, acid mine drainage (AMD) can become an issue. One approach to the control of AMD is desulfurisation whereby the sulfide minerals are removed prior to disposal. Four sulfide tailings samples, representing different ore types and gold and base metal operations, were selected for assessment and testing using simple physical beneficiation techniques. The aim was to determine the extent to which mineral processing methods were suitable for separating sulfides from non-sulfides and for extracting potentially marketable by-products from the tailings. In order to streamline the testing procedure a simple diagnostic separation technique was developed to enable quick screening of bulk sulfide tailings for suitability for reprocessing. The testing procedure involved detailed characterisation and a sequential set of testing regimes based on simple unit processes including water washing, classification, gravity concentration, magnetic separation and bulk flotation. The preliminary test results indicate each unit process can play an important part in producing effective sulfide/non-sulfide separations and in generating useful by-products from the tailings. Potential valuable products identified include coarse, benign silica sands, bulk iron sulfide products rich in pyrite and/or pyrrhotite, high-grade iron products (magnetite) low in silica, low-volume bulk sulfide concentrates and low-grade molybdenite and talc products. The work presented shows how sulfide tailings can be viewed as a resource rather than a waste stream, and identifies a pathway for developing a more sustainable approach to the environmental management of sulfide tailings for the future.

Jan 1, 2007

The paper is a general review of practice in design of sub-level open stopes in Northern Rhodesian copper mines and gives examples of some interesting developments during the last five or six years. It discusses the effect of hangingwall subsidence and the methods used to combat rock pressure on working areas.INTRODUCTIONAll producing mines on the Northern Rhodesian Copperbelt have large ore reserves and are designed for high rates of production. The three mines (Mufulira, Rhokana Corporation, and Roan Antelope) where sub-level open stoping is used, hoist from 250,000 to over 400,000 short tons of ore a month so that any stoping method used must be adaptable to concentrated' mining. Individqal stopes produce from 5,000 to over 25,000 short tons of ore a month.Structure af the ore bearing sediments is simple; faulting in ore is almost entirely absent and copper mineralisation is found in the same beds over great distances...

Jan 1, 1954

Samples weighing O· 2 g are digested with 2 ml of 72 per cent perchloric acid for 2 hr at 180°C, and then diluted to 10 ml. with water. After settling, an aliquot of clear solution is reduced with ascorbic-citric acid, and then a zinc dithiol solution is added to form a coloured molybdenum complex which is extracted with petroleum spirit for comparison with standards.Concentrations down to 2 p.p.m. may be analysed at rates up to 150 determinations per day.

Jan 1, 1970

A massive cobalt-containing pyrite orebody occurs in banded albite-quartz-biotite rocks at Thackaringa, some 30 km SW of Broken Hill. Because of the world-wide shortage of cobalt during the late 1970s, serious consideration was given to the development of a suitable flow-sheet to recover the cobalt from this ore. Details of a pressure leaching process in which more than 90 per cent of the cobalt is extracted from a pyrite concentrate are presented.

Jan 1, 1983

Individual specimens of sphalerite from the Broken Hill lode vary considerably in manganese and iron contents, even within the same orebody, so that study of the overall variation of manganese and iron content of the sphalerite calls for the analysis of a large number of specimens. This difficulty has been overcome by analysing a series of recleaned zinc concentrate products, prepared from stope samples and their equivalents, from most of the developed sections of the lode. The analyses reveal that during the formation of the sphalerite the concentrations of iron, manganese and zinc in the mineralizing solutions varied independently of one another from place to place in the forming orebodies, and also in time.The overall pattern of variation of the iron and manganese contents of the sphalerite in the several orebodies of the lode bears a general resemblance to the overall pattern of distribution shown by several other elements, notably, cadmium, lead, bismuth and arsenic. The iron content of the sphalerite indicates that it was formed at a temperature of 6000 C. or higher, but the variation in its iron and manganese contents demonstrates that Kullerud's method for determining the temperature of formation of sphalerite from its iron content must be used with caution if only single specimens of sphalerite are available.INTRODUCTIONThe four chemical analyses available of specimens of practically pure sphalerite from the Broken Hill lode (Table 1) reveal that the manganese content of the sphalerite varies considerably, and that there is a significant variation in its iron content. The variations revealed between individual specimens within the same orebody in the same mine suggest that specimen material is unsatisfactory as a basis for studying the overall manganese and iron contents of Broken Hill sphalerite, unless a great number of specimensis analysed.

Jan 1, 1956

Several factors contributing to the loss of fibre during treatment are a function of the paragenesis of the veins. The occurrence, of magnetite from the cap rock within the veins prevents complete fiberization. There is a marked similarity between these veins and those in the Koegas-Westerberg area of South Africa.INTRODUCTIONAn investigation of the mineralogy of the Wittenoom Gorge crocidolite veins was undertaken in the latter part of 1962 at the request of the Colonial Sugar Refining Co. Ltd. It was anticipated that such a study might reveal the cause or causes of the lack of recovery of some asbestos during beneficiation. Some interesting features of the mineralogy and paragenesis of the crocidolite veins become apparent, but it is emphasized that the investigation is far from complete, as the study did not extend to the field occurrence.The samples examined were selected from the mill and from the untreated ore.GEOLOGICAL SETTINGWittenoom Gorge is situated on the Fortescue River in the Hammersley Ranges of Western Australia and is one of several gorges in these ranges, on the sides of which 'crocidoIite asbestos is known to occur. The Hammersley, Ranges consist essentially of a series of quartzites, shales, ferruginous quartzites and dolomites. These' rocks are part of the Nullagine Formation (Proterozoic) and are usually either horizontal or gently folded. In some 'areas small beds of riebeckite as well as crocidolite are known to occur interbedded in the sequence.Riebeckite is a monoclinic amphibole, the formula of which may be stated as Na2Fe2"Fe2" (OH) 2Si8O22, and crocidolite is a fibrous variety of this mineral. This formula...

Jan 1, 1963

In presenting this address I am conscious of the honour that has been paid me in my election to this important office, and I am very aware that I follow, in the position of President, many distinguished men who have led the Institute over the 70 years since its inauguration in Broken Hill in 1893.It is perhaps appropriate tonight that I intend to talk about a metal which recalls the birth-place of the Institute, and is also one with which I have had a direct association throughout the whole of my working career. This metal is Silver.Silver is associated traditionally in everyone's mind with money and silverware, and has always been prized for its natural beauty and elegance. It is today one of the few metals in which world consumption has outstripped production, and the events which have occurred to bring about this situation make an interesting story.In telling this story, I propose firstly to indicate our development as a silver producing country, give an historical review of the metal, trace its use as currency and the factors influencing its price, and then say something of the old and new uses of silver. Finally I shall give some comments on silver production in Australia today.Australia, with 6-5 per cent of the world's output of silver, ranks sixth among the producer countries and over the years has contributed 892.5 million ounces to the world's supply which, based upon production since the discovery ofAmerica, is estimated to have been 22,150 million ounces or nearly 680,000 tons.Although our production appears relatively small by...

Jan 1, 1963

The area (330 sq. miles) shown on the map of the Brocks Creek District (Fig. 1), was mapped by the Northern Territory geological party of the Aerial, Geological and Geophysical Survey of Northern Australia. This work was done in two stages:-(i) In 1935, an area of 30 sq. miles around the Golden Dyke mine was mapped by P. S. Hossfeld, Senior Geologist, and A. H. Voisey, Assistant Geologist. The results were described in a detailed report (10).(ii) In 1939, an area of 300 sq. miles in the Brocks Creek district was mapped by C. J. Sullivan (Senior Assistant Geologist), and V. M. Cottle and S. N. Kiek (Assistant Geologists) under the general supervision of P. S. Hossfeld (Senior Geologist).An outline structural map, together with some geological notes was published (1), but that map does not show the amphibolites, and the relationship between ore occurrence and general geology is not emphasised. The publication of the detailed maps and reportwas postponed indefinitely as a result of war. The original mapping was based on air photographs with a scale of approximately 1 in. to 1,200 ft., and all detail which could be shown at that scale was mapped. Features recorded included rock types, details of structure, mineralisation, and surface workings, creeks and soil boundaries. Underground mapping was also carried out. The present map is much simplified from the original, but it is hoped that it shows sufficient information to reveal close relationship between structure, granite, sills of amphibolite and gold occurrence. About 50 per cent. of the area is covered by deep soil or alluvium, and in these portions the geology of the underlying rocks was not determined with accuracy, though in many places strike trends could be deduced from air photographs.Because the A.G. & G.S.N.A. had published the geological notes and map referred to above, and because the publication of the detailed report and maps is still postponed indefinitely, approval has been given by the Bureau of Mineral Resources, Geology and Geophysics (which took over the affairs of the A.G. & G.S.N.A. at the termination of its operations) to the preparation of the present paper so that information would be available to the public.The views expressed in this report are those of author. The results of the investigation suggest that in areas where granites are predominantly concordant with bedding, ore deposits may be found at approximately the same stratigraphic horizon. It is thus important to correlate beds even though their relationship may have been obscured by faulting and folding.

Jan 1, 1950

In referring to two subjects of interest to the Members of this Australasian Institute of Mining Engineers, I would at the outset desire to express our gratification that to-day we are able to welcome as now united with ourselves, those members who until recently constituted the New Zealand Institute. It is hoped that the amalgamation so amicably arranged may be productive of the best results to all concerned, incorporated as this combination has been at the moment of the fulfilment of that greater political union, the Australian Commonwealth.Since last Annual Meeting held in Brisbane, we have come under the same roof as the Chamber of Mines of Victoria, and we entertain the hope that as that Chamber and this Institute possess so many interests in common in the encouragement and advancement of mining and metallurgical progress in these colonies, that much mutual benefit will ensue. There are many directions in which each body can assist the other, and I trust that a friendly co-operation will be maintained.It is gratifying to feel that in all the colonies a distinct movement is being made to increase the facilities for education in Mining and Metallurgy but if I may refer to our colony of Victoria in particular, we have to express the profound regret that in the means of education in the higher branches, we occupy an inferior position, and it is quite certain that we will continue to do so unless the Government is prepared to subordinate provincial considerations to the weightier.

Jan 1, 1901

By Ruxton B. P, Rhodes J. M

Two Rb-Sr ages are discernible in data concerning the leucocratic granite which is the youngest pre-sedimentation phase of the crystalline basement complex at Rum Jungle, Northern Territory, Australia. Whole-rockdata suggest that intrusion of this unit took place at about 2400 my ago, with a probable initial ratio around o·707; whole rock-potassium feldspar tie-lines indicate redistribution of strontium at about 1800 my ago. The former age correlates with other measurements on rocks which form basement to the mantling Pine Creek Geosyncline; the latter correlates also with isotopic evidence for regional metamorphism and emplacement of some younger intrusive granites elsewhere within the geosyncline. A few K-Ar ages, from scattered localities, conform generally with the later event or events which appear to have some connection with the structural deformation clearly observable both in the complex and the surrounding metasediments. It is these younger events which appear to match the residual evidence for the earliest detectable concentration of uranium minerals in the Alligator Rivers district.

Jan 1, 1977

THE object of this paper is to review certain features in connection with the mining of narrow lodes, say up to 20 ft. or so wide. The types of ore-body to which it is intended to refer are those which occur. chiefly as fissure or shear-Iodes-that is, those lodes which are to be found in belts of country which have been subjected to dynamic stresses, resulting in the formation of cracks and fissures, into some of which has been concentrated sufficient metal-bearing material to form ores. Very frequently one of the walls of such a lode is found to be a fault, or plane of differential movement.The first point which comes up for consideration is the shaft and its position. From the information afforded by the prospecting which has been done on a lode relative to the dip, nature of country, &c., the position of the main hauling shaft can be determined. For purposes of general utility the hangingwall is generally chosen, if a vertical shaft, though, on account of freedom from creeps, the foot-wall would be safer. Vertical shafts are preferable to underlie shafts in many ways; but wherethe lode maintains a flat dip the cost of cross-cutting at the various levels becomes very heavy'. This difficulty may to some extent be modified· by sinking a vertical shaft in the hanging-wall...

Jan 1, 1912

Various steps, and complete sequences, for the recovery of lead and zinc from a mixed sulphide concentrate, high in silica and pyrite, have been tested.Oxidation steps of roasting in air or in a sulphating atmosphere and use of aqueous acidic, ammoniacal, and near neutral oxidation media were compared. Oxidation roasting or use of acidic media appeared most useful. Procedures for dissolution of zinc from calcines using sulphuric and sulphurous acid to avoid silica gelation problems are compared and a direct leaching procedure with sulphuric 'acid at controlled pH shown to be the most useful.Methods for the removal of germanium, nickel, and magnesium from zinc sulphate solutions prior to zinc electrodeposition were tested. The recoveries of zinc from ammoniacal solutions by electrolysis and distillation are compared.The dissolution of lead compounds from the residue of zinc extraction by amine and ammoniacal ammonium sulphate (AAS) solutions Was tested. Lead, sulphide was precipitated in filtera'ble form from AAS solutions. The reduction of lead sulphate to lead sulphide with sulphur was difficult, but possible. The various steps were used to deveiop five complete processing sequences, of which two were shown to be technically feasible and have potential economic viability.

Jan 1, 1975

By Johnston W. H

MINING operations in the Waihi mine began, under the present proprietorship in the year 1889. Previous to this, and as far back as the year 1880, the presence of reefs in the Martha Hill had been known, and surface working on a small scale had beencarried out, without any great measure of success. The only method of treatment in use at this time was the old system of light stamps, amalgamating tables and berdans, and recovery by this method being low, little margin for profit was left, so thatthe property in these days was not considered of great importance and work on the area was only carried on spasmodically by different owners.On the transfer of the leases to the present company, calcining, dry crushing, and hot pan amalgamation was adopted as the method of treatment, and this system was continued till the more modern cyanide process was introduced and applied. As themethods of treatment and gold-saving became more efficient with the application of more modern and scientific processes, the importance and future prospects of the mine became more and more pronounced, and mining on a larger and more comprehensive scale was gradually established.As in the case of ore treatment, mining methods in the early stages were not as far adv.anced as the adopted practice of today, and numerous shafts, levels close together in vertical height.

Jan 1, 1912

This paper describes a mobile laboratory developed specifically for nickel prospecting, and which was designed to be operated by sub-professional staff in remote areas independently of established laboratories. An atomic absorption spectrophotometric procedure was used to determine nickel, cobalt, lead, zinc, and copper ID latentIc and sulphIde samples, with a detection limit better than 25 µg/g for all elements. The procedure was applicable to both soil and drill samples and the accuracy of the procedure, which was ±5 per cent relative at the 1,000 µg/g level was sufficient for the preliminary assessment of mineralized samples and the control of drilling operations. The analytical procedure and the means taken to ensure the necessary reproductibility and accuracy are described. One operator can carry out 400 elemental determinations per 8-hr day at an approximate cdst of 6 cents per elemental determination. The results are returned within a single day, a factor which can contribute materially to the efficiency of drilling operations.

Jan 1, 1970

IN concentrating mills, where several millerals are recovered for realisation in more than one product, various systems are used to express the relative economic value of the work done, and, in the hope that it may prove of use to other operators, the writer will describe a system which, in his opinion, is more complete than any other that he has seen published.The controlling factor in all mill work must be based on the economic result represented by the greatest margin possible between the realizable value of the products and the cost of obtaining same.From a mill-man's point of view these are affected by the following factors:1. Metal contents of ore.2. Grade of products.3. Recoveries.4. Working costs.The grade of ore milled is usually outside the mill-man's control, but this may exercise a considerable influence on the grade of his products, metal recoveries, and revenue per ton of ore. Higher grades or recoveries may be obtained by using a more expensive process, or by additional grinding or reagents, and the economic comparison can only be arrived at by obtaining an analysis showing the monetary value of each variation within the possible limits.In the system to be described, the value of unit variations of metal contents of the ore, grade of products and recoveries are calculated in terms of a monetary unit per ton of ore with the returning charges ruling, and any suitable metal prices. To do this it is necessary to assume what, for convenience, is termed a "standard" set of results from the mill, preferably representing about average conditions, and having calculated the effect of unit...

Jan 1, 1931