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By A Rantala, K Aberkrom, O Haavisto, P Blanz

More complex ore bodies with lowering grades increase the challenges of maintaining high throughput, energy efficiency and required particle size for optimal downstream processing in grinding circuits. Continuous and often rapidly changing characteristics of the mill feed requires constant focus to operate the circuit at optimal level. Modern process instruments, on-line analyzers, monitoring and process control systems provide attractive and managed options to increase the circuits’ capability to respond to the challenge, often in phases and in rather short time period. Furthermore, well instrumented and performing base level automation in the grinding circuit enables advanced process control (APC) strategies that utilize measurements from the whole circuit to stabilize and optimize production. In this paper alternatives for incorporating process measurements and controls to typical grinding circuits are proposed. The expected benefits to throughput, availability, energy efficiency and particle size stability are described in recent case examples.CITATION:Rantala, A, Blanz, P, Aberkrom, K and Haavisto, O, 2015. Increasing grinding circuit robustness with advanced process control, in Proceedings MetPlant 2015, pp 129–141 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 7, 2015

The first part (lH of this work dealt with the process of recrystallization of single crystals of lead after deformation by creep, as revealed by macroscopical examination. It was shown that when recrystallization commenced, a crystal, termed the primary crystal, started to grow at the edge of the specimen and extended into the body of the specimen along the slip planes. At some stage during the growth of this crystal, other crystals appeared at the boundary of this first crystal and fragments of the parent crystal. From thispoint, recrystallization was accelerated with relatively rapid necking down of the specimen until fracture occurred.All those crystals formed after the primary crystal were given the term secondary crystals. In the present paper is given a detailed account of the orientations of the primary and secondary crystals.EXPERIMENTAL METHODThe size of the test pieces and the manner of loading were given in the previous paper (1). X-ray back reflection photographs were taken of the individual primary and secondary crystals and from them were determined the orientations. The path of the X-ray beam was perpendicular to the surface of the creep specimen.In view of the large number of photographs needed, gold...

Jan 1, 1940

ALTHOUGH great progress has been made in flotation of the Broken Hill silver-lead-zinc ores, no paper dealing with this subject has been presented to the members of the Institute since James Hebbard's valuable contribution in 1913. Almost every discovery or development in the history of flotation has formed the basis 6f a patent, and but few experimentalists have overlooked the fact that their investigations might lead to the establishment of a patentable process. This, together with the aftermath of patent litigation, naturally resulted in secrecy being maintained in matters appertaining to the art, and the industry as a whole has consequently suffered considerably. Much valuable time has been wasted through numbers ofmen repeating work along certain lines, which, unknown to them, had already been thoroughly exhausted by others, whereas a lot of this would have been avoided by a freer interchange of information amongst those directly concerned. Owing to differences in the ore treated and the various applications of flotation concentration in relation to gravity methods, the flotation problems of the various mines differ considerably. This, together with the secrecy previously referred to, hasresulted in the development of numerous systems and machines, most of which would appear, to the casual observer, to comprise separate and distinct processes. The author has endeavoured to show how much these processes have in common with one another, and, at the same time, has tried to convey some general ideas on flotation to those members of the Institute who are not directly associated with this branch of concentration.

Jan 1, 1919

Lead isotope measurements indicate that lead from the A.B.H. Consols mine and two transgressive veins in Browne's shaft is "Thackaringa" type and not "Broken Hill" type.

Jan 1, 1970

By J L. Mauk

The Gladstone Hill area hosts epithermal veins similar to those at Martha Hill, which is less than one kilometre away. There are several vein types in the Gladstone Hill area including (1) pyrite-marcasite, (2) quartz, (3) base metal sulfide, and (4) calcite. Pyrite veinlets formed first, whereas the quartz and carbonate veins formed later. The base metal sulfide vein occurs at depth and is predominantly comprised of quartz and chlorite intimately intergrown with pyrite, sphalerite, galena, and rare chalcopyrite. Platy calcite and massive calcite veinlets were the last vein types to form. Several vein textures occur in the Gladstone Hill area, including colloform and crustiform banding, lattice-bladed, zonal, comb, massive and feathery textures. Crustiform banded veins are the dominant texture and contain variable gold-silver grades. Colloform banded veins consist of ubiquitous quartz and minor chalcedony with gold grades as high as 60 g/t. The lattice-bladed texture forms from the deposition of calcite, which has been replaced in many samples by quartz, indicating that boiling and later cooling has taken place. Unreplaced platy calcite only occurs at deeper levels (>300 m). Zonal and comb textures are preserved in quartz and late-stage amethyst veins. Feathery textures within quartz are commonly associated with breccias and some colloform banding, and with significant Au-Ag grades.   The homogenisation temperatures (Th) of primary and secondary inclusions in quartz, amethyst and platy calcite range from 166 to 274¦C, with salinities <1.3 wt% NaCI equiv. The presence of vapor-dominated inclusions and primary fluid inclusions in platy calcite suggests that boiling occurred intermittently throughout deposition. The veins formed under a relatively flat lying paleowater table that occurred 280 - 300 m above sea level. The fluids involved in vein formation were alkali chloride in composition and low in CO2.

Jan 1, 2001

By K H. Esbensen

The Theory of Sampling (TOS) has made remarkable strides and has witnessed a suite of achievements over its ~65-year history; especially in the last 15 years, since organised work began for the erstwhile fragmented sampling community (2003). Theory and practice have been very well exposed and disseminated, as witnessed in the successful series of the World Conference on Sampling and Blending (WCSB) events and other dedicated sampling and mining conferences in Australia and South Africa. At this WCSB8 occasion we fittingly devote a section of our conference to celebrate the life and monumental achievement of Pierre Gy, the originator of the Theory of Sampling; a special issue of TOS Forum was recently published to the same purpose. But TOS is most emphatically not a finished work.Here I try to look into the future with a personal view: TOS – what’s next? Commensurate with this objective there is offered some out-of-the-box thinking. The purpose is to try to zoom in on probable additional future aspects of TOS and its application compared to the first 15 years of our common journey. There are bound to be lacunae here-and-there across the vast application horizon delineated, which is as it should be, as this lecture is meant to initiate a broad(er) debate – and readers may agree with all, parts, or none of the topics presented. All is well that furthers this debate.CITATION:Esbensen, K H, 2017. Theory of Sampling – what’s next?, in Proceedings Eighth World Conference on Sampling and Blending , pp 29–38 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2017

The treatment plant at Martha Mine was upgraded from a nominal throughput of 110tph (O.93mtpa) to 150tph (1.25mtpa) late 1999. Post-upgrade performance did not meet expectations when treating either the competent primary ore or the clay-rich oxide ore.   ò Plant throughput is constrained by milling capacity when treating the competent primary ore. This is not an issue at present as current plant feed is oxide ore from the top of the open-pit, but will become so in future years as the pit deepens. To counter this future threat, ball mill power has been restored to 1100kW through modifications to the drive train. The addition of a crushing circuit may also be necessary.   ò Plant throughput was originally constrained by thickener and leach/adsorption tank issues when treating the oxide are. Changes to plant equipment and operations has seen the removal of these constraints and throughput on this material is no longer a problem.   The most significant issue facing plant staff at present is the high silver grade and its impact on gold recovery. These high grades impact upon recovery through losses caused by insufficient leach and adsorption capacity. To counter this, the geology, mining, and milling teams are working together to blend the high grade silver zones with lower grade ores - this is seen to be the quickest and most cost effective way to deal with the issue. The plant design has also been evaluated with a view to modifying it to cope with the higher silver grades. The viability of these modifications will depend on cost and time (that is, the length of time to implement any modifications versus the length of time to mine out the high silver zones).

Jan 1, 2001

By J K. Claflin, S R. La Brooy

A case study from a current Ausenco project is presented to demonstrate the importance of maintaining high carbon activity to illustrate the driving force for plant improvements such as a carbon regeneration kiln upgrade.This paper revisits the factors that influence carbon activity for gold loading, with emphasis on deactivation by organic solution components such as flotation reagents.Kiln process design requirements for effective thermal regeneration are reviewed including the interaction of parameters such as temperature, kiln atmosphere and residence time.The different types of kilns that have been used for carbon reactivation are described. A check list is provided of what to look for when purchasing a carbon reactivation system for dealing with severely fouled carbon. This covers the ancillary equipment as well as the kiln itself.While the effectiveness of the carbon reactivation kiln is vital to maintenance of high carbon activity it needs to be remembered that this is only the end of pipe solution. It is also important to ensure that reagents such as frothers and flotation collectors are appropriately chosen to maximise recovery and at the same time minimise carbon deactivation.CITATION:La Brooy, S R and Claflin, J K, 2013. Carbon management in a high gold price environment, in Proceedings MetPlant 2013 , pp 455-467 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 15, 2013

By Z S Chang, T F. Zhou, G X. Zhong

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. The Yaojialing zinc-gold polymetallic deposit is a newly discovered, large skarn deposit in the Middle-Lower Yangtze metallogenic belt, East China. It is located in the transitional zone between the Tongling uplift block and the Fanchang faulted basin. It is mainly hosted in the contact zone between early Cretaceous granodiorite porphyry and Carboniferous-Triassic limestone, or occurs in limestone xenoliths within the intrusion. Skarn and stratabound massive sulfide orebodies are the primary ore styles. Sulfide ?34SV-CDT values indicate a magmatic sulfur source, in common with most deposits in the Tongling block. Calcite d13CV-PDB and d18OV-SMOW ratios reveal that marine carbonates were the major source of carbon in late-stage hydrothermal fluids. The calcite probably formed during interaction between magmatic fluids and carbonate wall rock.CITATION:Zhong, G X, Zhou, T F and Chang, Z S, 2015. Geology, chronology and isotope geochemistry of the Yaojialing zinc-gold deposit, Tongling ore district, Anhui Province, China, in Proceedings PACRIM 2015 Congress, pp 457–462 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

By KEITH BARRONI

In the proposed criterion for coal a distinction is made between brittle and "psuedo-ductile" failure. This criterion is the basis for the development of new equations for coal pillar strength, including a transition from brittle fracture to pseudo-ductile yielding. In addition the equations obtained allow the critical minimum pillar dimensions to be calculated to avoid "catastrophic" and "ultimate failure".The validity of these formulae can be tested by comparing their results with pillar case histories derived from the literature.

Jan 1, 1988

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

It is possible to divide industrial minerals into four general categories: 1. fuels, 2. construction materials, 4. agricultural minerals, and 4. industrial minerals. It is proposed to ignore the fuels in the context of this paper and deal in general terms with the others. Mining companies have often considered getting into the industrial mineral business because they can see a resource development with good growth and consistent profits. However, many mining companies being conversant with the metallic side of the industry have spent sleepless nights determining which industrial minerals are most suited for their particular situation. Some have got into the business for the wrong reasons and wished they had never heard of it. Others have successfully adapted to the industrial minerals philosophy and now operate in both metallic and industrial mineral arenas. There is a large difference between firstly, the philosophy and secondly, the functions of being in the industrial minerals business as opposed to metallicÆs. The philosophies can be considered in parallel but it is necessary to clearly have an appreciation of the dominant influences that affect industrial minerals.

Jan 1, 1984

By Beevers J

The Ok Tedi Project is now a high production open-pit porphyry copper mine located in the Star Mountains of Papua New Guinea (PNG). At present, total daily production is 190 000t of ore and waste. Large scale drilling and blasting has only been in operation since 1988, prior to which all material was removed by ripping and dozing. This paper reviews the steps taken over the last 12 months in establishing a more efficient drilling and blasting operation and highlights the significant reduction in powder factor. These improvements have been achieved largely through the introduction of air-bags, controlled pattern expansion and an overall focusing on the operation by involving consultants, ICI's technical service and internal departments.

Jan 1, 1991

Comparison of Grinding and Liberation Processes for Stalky Biomass Materials as a Prerequisite for Production of Energy Pellets with High Calorific Value Pelletising biomass, especially straw and stalky materials, requires a product specific size reduction and liberation. However, moisture content plays an important role in palletising and also affects the energetic properties of the biomass. The paper illustrates the characteristics of the mentioned type of biomass and specifies the necessities for production of energy pellets. Defined requirements for biomass energy pellets will be shown based on relevant standards. The work focuses on a comparative investigation of the straw fibres after grinding with hammer/impact mill and after the liberation of the straw fibres with twin-screw extruder (two different communition units). A traditional hammer mill as well as an hydrothermal process taking place in a twin-screw extruder were utilised. Results of the grinding and liberation of rye and wheat straw fibres are discussed based on a detailed particle characterisation (particle size and shape distribution). Besides high calorific value the main pellet quality parameters are mechanical stability, abrasion resistance and further combustion technical characteristics. The particle size distribution displayed optimum characteristics for the combustion processes to be carried out in a furnace. The durability of the pellets produced from straw fibres liberated with twin-screw extruder was comparatively better then that prepared with the straw fibres after grinding with impact mill. Particle size distribution, abrasion values and the strength characteristics showed a good correlation with each. The high presence of N and S would result in high NOx and SOx emissions, where as the high concentrations of Cl would corrode the furnace. These chemical properties of the straw would restrict its usage in small scale furnaces.

Sep 13, 2010

The ore milled from the Lead Lode of The Zinc Corporation leases consists of a fairly granular mixture of galena, marmatite, chalcopyrite, tetrahedrite, pyrrhotite, pyrite, and lollingite with a gangue association of calcite, quartz, bustamite, rhodonite, mangan-hedenbergite, garnet, fluorite, mangal1o-calcite and apatite. The silver content of the ore occurs in three minerals-tetrahedrite, dyscrasite, and pyrargyrite, the last two mentioned occurring in microscopic association only. Other metallic and gangue minerals are also present in this complex mineralogical association, but do not influence the milling operations. Fortunately, the silver minerals favour the galena and chalcopyrite as their host minerals, thus facilitating the recovery of both copper and silver in the lead concentrate. The ore from the Lead Lode assays from 14-18% lead; 3·0-4·5 oz. silver per ton, and 9·5-12·0% zinc.A parallel lode, known as the Zinc Lode, is well developed in The Zinc Corporation leases. This lode assays from 6-8% lead, 1·5 oz. silver per ton, 18-25% zinc with a siliceous gangue. The common Lead Lode gangue minerals-ealcite, rhodonite, bustamite-are very rare in present underground exposures. No metallurgical work was done on this ore during the pilot plant operations.The aim in the milling process is to produce: 1. A lead concentrate with the maximum economic recovery of lead, silver, gold, copper and antimony, and minimum zinc content.2. A zinc conc,entrate with the maximum economic recovery of zinc, cadmium, and cobalt, and minimum iron, arsenic and fluorine content.3. A waste residue containing sufficient granular material to be utilized as underground fill.In considering the economics of the milling practice the above three requirements plus consideration of the tariffs submitted by the purchasers of concentrates were the deciding factors in the evolution of the present milling practice.Towards the end of 1924 The Zinc Corporation Limited added to and adapted the old zinc tailings plant for the treatment of 5,000 tons of crude ore per week. This plant, which operated until January, 1936, was in general principles similar to the standard Broken Hill methods of ore concentration, whereby the galena was recovered by the gravity concentration methods of Hgging and tabling with selective flotation concentration of the residual galena and marmatite. One important difference from other Broken Hill plants was that the primary grinding of the jig tailing was performed with flint-loaded mills operating in closed circuit with revolving screens. Two primary grinding sections were installed, each...

Jan 1, 1941

It is now five years since the advent of gold-dredging in Australia, the State of New South 'Wales, or colony as it was, being the first to adopt this system of gold-getting, and the credit of its introduction rests with a member of this Institute, Mr. Chas. L. Garland, who commenced operations with his dredge on the Macquarie River, at the junction of the Muckerawa Creek, in the month of March, 1899. In this paper it is intended to give a brief history of the career of the gold dredge in New South Wales from that relate up to the present time, during which period the writer, as a designer of many dredges, has been constantly in touch with the subject in all its phases in this State; the points noted are the outcome of his observation in a general way, and to a great extent are apart from the design proper.Gold-dredging in New South Wales up to the present moment can hardly be designated an unqualified success...

Jan 1, 1904

By Williams K. C

This paper presents a brief account of the plant which has been developed at Port Pirie to recover, by vacuum distillation, the greater part of the zinc content of desilverized lead. The present plant is an experimental unit, which is run in conjunction with the normal refinery practice, but can be cut out of the circuit. It will shortly be dismantled and duplicate units will be built on the sites chosen for the final plant installation.The unit described here has treated flows of 16 to 37 tons per hour of desilverized lead, to recover 90 to 95 per cent of the zinc contained in it. It is not intended here to detail all aspects of the vacuum dezincing operation, nor the developments which precededthe adoption of this design. The essential features of the present plant will be described and, where these are peculiar to the present experimental location, the intended alteration for the final plant will also be mentioned. OUTLINE OF PLANT AND PROCESSLead issues from the continuous desilverizing kettle at about 350° C. containing about 0·57 per cent Zn. It is conveyed by a tiled launder to the preheater, where it is heated to 580-620° C.Hot lead from the preheater enters the vacuum vessel via a barometric leg. From a reservoir holding about 19 tons of lead it falls by gravity in a thin film exposed to high vacuum (20-50 microns)3 and leaves the vessel via a barometric leg, entering the lead pot. The lead leaves this pot at 540-560° C., containing 0·03 to 0·06 per cent Zn, which is removed, together with residual antimony of 0.02 to 0·06 per cent, by a separate final refining process.

Jan 1, 1956

Newcrest Mining Limited (NML) owns and manages the Ridgeway Gold Mine (RGM) located outside Orange in the state of New South Wales. RGM is a new underground sublevel caving (SLC) operation that is ramping up production to 4 Mtpa. The success of the SLC method at RGM is strongly influenced by production drill and blast practices. Distinguishing features of the Ridgeway SLC operation include choke blasting against broken rock, drawpoint brow preservation, loading of blastholes with different in-hole bulk emulsion densities, precharging of production rings and routine drawpoint fragmentation assessment. These areas are described in the context of RGMÆs required blasting objectives, production drilling and charging activities and innovative practices.

Jan 1, 2002

By A N. Danoucaras, S E. Goater, D Hearne, A M. Bansuan

It is globally recognised that existing and emerging mining activities should be conducted in a æsustainableÆ manner for the entire life of mine. Many companies annually publish corporate sustainability reports to demonstrate their actions in accordance with international expectations. This concept of sustainable mining practices also applies to mine water management, with influences often extending beyond site operations, affecting surrounding catchments and community users. This paper explores differences in conceptual and operational terms of æsustainableÆ mine water management within the Philippines. Outcomes of a review of corporate sustainability reports, governance documentation, research programs, and stakeholder knowledge acquired through action-research workshops are presented. The paper aims to inform and support future capacity building exercises delivered by the International Mining for Development Centre (IM4DC), with outcomes tailored to government officials and policy makers of developing countries. The project is funded by IM4DC, which is working with AusAID to identify needs and develop capacity with regard to mining for development; specifically, issues pertaining to governance and regulation, social and environmental sustainability, and operational effectiveness in developing countries.CITATION:Bansuan, A M, Goater, S E, Danoucaras, A N and Hearne, D, 2012. Integrated sustainable water management in mining for development in the Philippines, in Proceedings International Mine Management 2012, pp 205-226 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 20, 2012

Currently raw brown coal is fired in the Latrotx; 'ahcc th,iki~, Lanying with it two major penalties, (a) boiler efficiency of 65 - 70 per cent (in terms of GCV), (b) much higher boiler cost than for black coal. Drying the coal, in energy-efficient, and cost-efficient manner, opens the way to efficiencies of order 88 per cent and enables the lower cost black coal type boilers to be used. With the higher boiler efficiency goes much higher combustion temperatures and the effect of this on radiative heat transfer is a major factor in reducing boiler cost. In a fluidised-bed combustor the temperature is controlled to 800C - 900C. In a pulverised fuel combustor higher temperatures are however achieved and can increase boiler fouling due to the salt content of the coal. This is a problem which needs to be solved. Victoria has the prospect of lifting efficiency from 28/29 per cent to 35 per cent, of reducing carbon dioxide output correspondingly and reducing cost of power stations. So far as gasification is concerned, efficient removal of liquid water from the coal is important to the overall efficiency.

Jan 1, 1992