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By L Blackwell

Strategic mine scheduling is an industry best practice for increasing the long-term value of mining operations and supply chains. The application of optimisation technology such as mixed integer linear programming (MILP) is able to achieve a mathematically optimal result for a given scheduling model. Such a model will typically define the available source material, processing options and desired constraints for accessing and processing the material. Most strategic scheduling models, however, do not include a sufficiently detailed model of capital expenditure options related to capacity expansion.Typical strategic schedule models do not include important capital expenditure features such as capacity decay or expiration (limited lifespan of trucks), precedence relationships over time (rail construction before a new plant or non-linear expansions due to economies of scale) or mutually exclusive option sets (choices of plant size). By not including these features, a strategic mine scheduling model for a capital-sensitive operation is unable to be optimised to deliver maximum value or profitability.This paper presents several results of MILP optimisation using advanced capital expenditure modelling for mining operations and supply chains. Results of the study demonstrate that optimising capital expenditure at the same time as optimising the mining schedule allows for minimisation of capital purchasing, optimal timing for those purchases and optimal scheduling around them. Overall, this results in an increase in net present value.CITATION:Blackwell, L, 2014. Capital expenditure modelling for strategic mine scheduling, in Proceedings Orebody Modelling and Strategic Mine Planning Symposium 2014 , pp 315–322 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 24, 2014

This paper is directed at the problems flowing from Australia's capital gains tax (CGT) on the disposal of exploration and mining tenements both in Australia and overseas. It will seek to identify the issues and give some idea of the dollar consequences of decisions lacking forethought. The paper should not only be seen in the context of Australian tenements. CGT applies to the disposal of any assets by an Australian resident anywhere in the world. Offshore incorporated companies are not necessarily free from CGT risk where it can be shown that control management and control of the relevant company is in Australia. Also the disposal by non residents of Australian tenements are potentially caught by CGT. Some will ask what has taxation got to do with a valuer who merely determines the value of assets. These days no determination can be blind to the consequences. Whether the consequences can encourage a movement in value is another thing dependent upon the circumstances; but? A role of an experienced taxation consultant is to point out parameters within which associated professionals can work. The parameters will vary from case to case, but these when clearly indicated may be of help to persons such as valuers. When one comes down to it real estate salesmen are never wrong. They have a feel for the market and almost through self fulfilling prophesies achieve sales at their guestimates. Whether they could have achieved higher considerations become virtually academic in the process. Of course I am not suggesting that tenement valuers can be compared to real estate salesmen, or am I? What is the value of a tenement? Is it the DCF/NPV type of generated value based on a large number of variable factors (ie what one may call the fundamental value)? Or is it what another may pay to purchase that tenement if it were on the market at an instant point in time? How big is the market, the quality of the bidders, the size of their purses, the needs of the buyer for comfortable fit, the premiums for foreigners, the standard of the marketing, the industry intelligence level of the bidders, the obligation to farm/sell down? The list goes on endlessly. One question must be.asked-"Is a range of values acceptable for tax purposes". ie Would any tax consultant ever provide a valuation to the Australian Taxation Office that indicates three or more possible values ie

Jan 1, 1987

The optimisation of capital in the total planning context has broadly two components: ò maximising the efficient utilisation of capital against competing capital demands; and ò maximising the efficiency with which the industry's capital requirements are sourced. This paper focuses on the latter of these two concepts, as I wish to highlight that within the coal industry the inefficient sourcing of capital has resulted in the inefficient utilisation of capital. In discussing the optimisation of capital within the coal industry I would like to outline three fundamental issues which currently impact the industry and its application of capital: Initially, from the perspective of an independent investor, the perceived risk associated with investing in a volatile industry cycle has not permitted appropriate funding structures to be created thus leading to an inefficient utilisation of capital. Secondly, investors seeking out a windfall gain have established a practice of trading in the assets rather than encouraging recapitalisation. And lastly the mismatch of supply and demand leading to the establishment of new projects which include a percentage of offshore investment has fostered an environment of lower returns and subsequently a dilution of capital.

Jan 1, 1991

By Thomas R

The successful `marriage' between a company seeking to raise funds to develop a project and their financiers calls for a strong mutual understanding of each other's needs. For a company attempting to raise funding, the alternative methods are ever expanding. The optimum method will vary depending on the financial position, risk/reward outlook of the company and the strength of the project for which development capital is being sought. It is likely that small mining companies will need to raise equity funds for advancing projects to the development stage. At that time, they will probably still require a reasonable level of shareholder equity to meet the requirements of banks and other parties to cover potential cost over-runs on the project and feasibility costs. Larger companies, however, are likely to find it much easier and cheaper to raise debt from banks. When evaluating companies and projects for funding, banks will pay particular attention to the quality and experience of management in developing similar projects and it may be necessary for some companies to retain the services of outside consultants. Before a project needs funding, companies should meet with potential financiers to develop relationships to select and ensure a smooth transaction to funding in the future.

Jan 1, 1997

In the Broken Hill South mine tile practice of issuing to the miner a quantity of fuse and a box of caps from which he made up the "rods" required for a particular blast, has been abandoned. Instead, capping stations have been established, and the miner can now obtain, from the magazines, fuses cut to accurate lengths with the detonators attached.Various types of fuse-cutting machines and crimping devices are available, but only those used by the Broken Hill South Mine Ltd. are described in this paper.The fuse-cutting machine, designed by the engineering staff, is an electrically driven unit fitted with a gear box for the purpose of adjusting the rate at which the fuse is fed to the cutting device, thereby enabling fuses of various lengths to be accurately severed from the main coil of fuse.The machine in question is designed to cut 4, 6, and 8-ft. fuses, but no difficulty should be experienced in designing a machine to cut fuses to any required lengths.

Jan 1, 1932

By Costello MC

An alternative process for desorbing and recovering metals from activated carbon has been developed, and is the subject of several patent applications by Micron Research (W.A.) The system uses the principle of conditioning the carbon in a strong alkaline cyanide solution followed by distillation desorption in a fractionating column, using the carbon as the column packing and methanol as the desorbing agent. The system offers the following advantages : (a) The processes of desorption, methanol recovery and reactivation are all carried out in a single column with the carbon itself acting as the column packing. No other desorption plant items or fractional distillation equipment are required. (b) The metal values are concentrated into the water content of the carbon and no other water is used except as condenser coolant. This produces very high grade gold silver solutions which give high current efficiencies in the electrowinning step. These high gold concentrations allow almost complete separation of gold and silver from copper in the electrolytic cell. (c) The process is completed to a tailing assay of less than 200g Au/tonne carbon in 15 - 20 hours allowing turn around of carbon batches on a daily Basis.

Jan 1, 1982

By G H. Park, Y J. Jun, J H. Park

The carbon solubility of the CaO-Al2O3-FeO-SiO2-MgO slag, the main system formed in the Ruhrstahl-Heraeus (RH) vacuum degasser, was measured at 1873 K to understand the effect of slag compositions on the carbon contamination in the ultra-low carbon (ULC) steels. The stable form of carbon was demonstrated to be carbonate by plotting the log [(wt%C)/aC] ratio against the log p(O2) which ranged -11 < log p(O2,atm) < -9. The carbon solubility of the CaO-Al2O3-FeO-SiO2-MgO slag can be estimated using thermodynamic model. The distribution ratio of carbon increased with increasing concentration of FeO due to the FeO reduction reaction and increased basicity of slag. The carbonate capacity of the CaO-Al2O3-FeO-SiO2-MgO slag can be expressed as a linear function of the activity of lime and the optical basicity.

Jun 19, 2024

By J K. Claflin, S R. La Brooy, A M. Claflin

Rotary kilns have been in service in the gold industry to regenerate carbon for 65 years. At the time oxide ores with gold head grades of 8 to 10 g/t were being treated. Carbon could be regenerated adequately at 650&#176;C and solution losses were less than 1%. Forty years ago, research indicated that heavily fouled carbon from flotation circuits had to be held at 750 to 850&#176;C for ten to twenty minutes for full reactivation (Avraamides and La Brooy, 1987), gold head grades were typically 5 g/t and solution losses typically 0.02 ppm – still less than 1%. In 2017 it was determined (Claflin et al., 2017) that a residence time of less than 1 minute at 750&#176;C can be adequate to reactivate carbon fouled with organics sufficiently to achieve 0.005 ppm solution losses in a flotation tailings leach plant.With the potential for discovery head grades to drop below 0.6 g/t, solution losses of 0.02 ppm represent over 3% loss. Tight operation of the whole carbon circuit is required to keep gold solution losses below 1% going forward.There are alternatives to a rotary carbon kiln, e.g. vertical kilns of which the Minfurn, Rintoul and Combustion Air kilns are examples. The alternative kilns can be heated using electrical heating elements, induction, and microwave. These kilns can operate successfully under the right conditions, however, they are almost exclusively for small carbon throughputs and are not suitable for the large carbon advance rates that are required to process low head grade ore deposits. Large throughput carbon kilns are are almost exclusively fossil fuel fired rotary kilns and the subject of this paper. In the view of the principal author, a fossil fuel fired vertical carbon kiln is preferred to a rotary kiln, however, it is not currently used in the industry.Thermal regeneration of activated carbon has a major impact on gold recovery in the carbon circuit. The carbon kiln and associated equipment constitute 3 to 5% of the capital cost for an oxide processing plant and up to 10% of the capital cost if flotation tails are leached. Despite the capital cost and impact on recovery, the carbon kiln is often poorly selected, operated and maintained.Six years ago Ausenco embarked on the Carbon Kiln Initiative to reduce solution gold losses. This body of knowledge has been published in a series of papers culminating in this paper on how to:1. Select a kiln appropriate for the flowsheet;2. Maintain the kiln to achieve design operation; and3. Operate the kiln to minimise costs and maximise reactivation.CITATION:Claflin, J K, La Brooy, S R and Claflin, A M, 2018. Carbon kiln selection, operation and maintenance, in Proceedings 14th AusIMM Mill Operators&#39; Conference 2018, pp 251–274 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 29, 2018

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 D G. Rantucci

Organic carbon is a major ore contaminant at MMG’s Century mine. This carbonaceous matter is associated with shale hosted sphalerite mineralisation. It occurs as elongated lamellae and as inclusions in porous sphalerite aggregates which are fine grained and difficult to liberate from sphalerite. The carbon prefloat circuit was designed to remove the liberated organic carbon in order to mitigate excessive reagent consumption, contamination of the lead and zinc concentrates and poor flotation performance in the primary zinc circuit. The consequence of organic carbon removal is that sphalerite and galena minerals are lost to the prefloat concentrate. A Jameson Cell was installed in late 2005 as a prefloat cleaner cell. Operational experience showed that the cell became capacity limited during periods of high amounts of organic carbon in the feed and was subsequently bypassed.Reactive style operating strategies were implemented to manage the effects of insufficient organic carbon removal by the prefloat circuit but due to the relatively large circuit residence time, upstream changes meant hours before the downstream circuits were stabilised following a disturbance from excess carbon.This paper describes the modifications and testwork undertaken to enable the Jameson Cell to be operated during periods of high organic carbon in the float feed and the implementation of process control initiatives to proactively remove the required prefloat mass from the float feed to eliminate the reactive style operating strategy.The process control modifications centred on dynamically targeting a prefloat mass recovery determined by an equation relating the carbon to zinc ratio to the carbon prefloat mass as a percentage of the float feed. The equation was developed by analysing historical data. These improvements served to optimise the prefloat circuit and consequently stabilise the downstream lead and zinc circuits.

Aug 8, 2011

By Greaves J. N

The U.S. Department of Interior, Bureau of Mines, is investigating the treatment of refractory gold ores. Chlorination in the treatment of refractory gold ores is applicable in many low-grade gold operations. When usable, this treatment provides an economic means of consuming sulfides and deactivating disseminated organic carbon. Chlorination, however, is a pretreatment technique that requires the neutralization of the chlorine prior to leaching the ore with cyanide. Research by the Bureau has extended the present chlorination technology to allow for the recovery of gold without the use of cyanide and allow treatment of some ores presently deemed untreatable by gold operators using cyanidation or chlorination/cyanidation techniques. Chlorination without carbon of two carbonaceous ores extracted between 1 and 20 pct of the gold; however, carbon-in-chlorine (CICL) treatments resulted in about 90-pct recovery with a reduction in carbon loading. A statistical design campaign for stripping metallic gold from the carbon loaded in a chlorine environment demonstrated elutions exceeding 90 pct.

Jan 1, 1991

The carbon-in-pulp (CIP) process is now well established in the South African gold industry, with a total of over I million metric tons of material being treated each month in six large plants. This tonnage is derived from ground ore, from filtered pulp, from calcine, and from reclaimed sand-tailings dumps. With this new process and the new large plants, those concerned with CIP are experiencing a learning process, since each new plant presents a different set of problems to be overcome. The knowledge and experience gained from these plants is being shared, and will be of benefit in the design and operation of new plants. The CIP process can be subdivided into the following unit operations: prescreening at a fine size, adsorption, acid-washing and elution, reactivation, and electrowinning. Results concerning each of these unit operations, which were obtained from pilot plants and from large-scale CIP plants in South Africa, are presented. The latest developments in each of these areas is summarized. Tables that are included as an appendix contain some information concerning the equipment in these new CIP plants plus operating results from some plants.

Jan 1, 1982

I am very pleased to be here at this seminar on carbon-in-pulp (CIP) technology for the extraction of gold as I am always interested to hear about any new development in any aspect of gold ore processing. We can expect to learn a great deal from the papers to be presented over the next few days. It is not my purpose to give a detailed description of the CIP process nor to give a complete historical review. However, in this opening address it was thought appropriate that I should mention some historical features and some technical factors to set the scene for subsequent papers. HISTORICAL NOTE Table 1 shows some interesting dates of the use of carbon in gold metallurgy in Australia. Mount Morgan used carbon after chlorination TABLE I Carbon precipitation in Australia 1891 Mount Morgan 1917 Yuanmi mine (Edmunds) 1934 Sons of Gwalia (Edquist) 1975-1980 Various pilot plants and small companies 1980- Various large and small plants

Jan 1, 1982

By Sehic OA

One aim of testwork and flowsheet development is to ultimately provide a reliable and flexible plant that is simple to operate and maintain. Testwork can indicate amenability of ores to CIP treatment and provide a basis for process design and economic appraisal. Batch cyanidation and CIP tests are often sufficient for small projects. Continuous multistage test rigs can be operated to simulate plant operation and to provide data for flowsheet optimisation. Operating requirements, gold recoveries and potential problem areas can be anticipated at an early stage with more confidence. Subsequent project development involving decisions on the basic flowsheet, equipment types and general plant arrangements are based on practical considerations and experience. Computer aided process modeling and economic appraisal can be useful in analysing various tradeoffs, firming up the flowsheet and equipment sizes, and in specifying operating targets for the future CIP plant. INTRODUCTION Carbon-in-pulp (CIP) technology which has developed rapidly since 1974 is now accepted as an economically and technically viable process for the efficient recovery of gold. This paper describes testwork and flowsheet development procedures used for CIP evaluation and design.

Jan 1, 1982

By M Barley, C A. RosiFre, L Lobato

The Carajßs iron ore deposits contain approximately 17.5 billion tons of ore with >64 per cent Fe and occur in the eastern part of the Amazonas Craton. They are hosted by jaspilitic banded iron-formation (BIF) of the Carajßs Formation which, together with metavolcanic rocks, comprise the ~2.75Ga Grpo Parß Group of the Itacai·nas Supergroup in the ~1000 km long, E-W trending Carajßs Synclinorium. The Carajas Formation comprises discontinuous layers and lenses of partly dolomitised BIF (17 - 43 per cent Fe and 35 - 61 per cent SiO2) and lenses of high-grade iron ore, cut by mafic sills and dykes. The high-grade iron ores occur as large tabular bodies of friable (soft) hematite with smaller lenses of hard (compact) hematite. The hard hematite ores typically occur at the contact with the underlying volcanic rocks and are surrounded by an aureole of hydrothermal carbonate alteration. BIF that has been overprinted by dolomite and magnetite crystallisation has recently been discovered at depth in the N4E Mine. With increasing amounts of carbonate, the original lamination (microbanding) and other fine primary structures in the BIF have been progressively obliterated resulting in alternating carbonate and iron oxide mesobands. The friable hematite ore that is characteristic of the Carajßs deposits results from ongoing weathering and leaching of the carbonates from this type of altered BIF. The hard hematite ores probably result from more extensive early oxidation. The association of both carbonate-altered and jaspilitic BIF with the N4 Mine is similar to that observed at the Mount Tom Price deposit in Western Australia, where carbonate-altered BIF occurs below massive hematite ore with a jaspilitic halo developed above the orebody. This indicates that as at Mount Tom Price, hydrothermal carbonate alteration and associated loss of silica from BIF may be an important step in the formation of these giant hematite deposits.

Jan 1, 2002

By G R. Dickens, N H. S Oliver

The genesis of giant hematite ore deposits in northwest Australia remains a contentious topic in part because key evidence supporting a unifying genetic model has not been found at all deposits. In particular, several papers have proposed that carbonate replacement of silica layers in banded iron formation (BIF) by basinal brines is a requisite first step toward ore formation. This initial hypogene stage is inferred primarily from the presence of silica-poor, carbonate-rich rocks found below ore and along normal faults at the Mount Tom Price and Giles Mini deposits. However, until recently such rocks have not been identified at the largest martite-microplaty hematite deposit, Mount Whaleback. In this study, samples of the upper Mount McRae Shale are examined for their chemistry, mineralogy and petrography. These samples were collected from several key locations, including within drill core that penetrates an area immediately beneath ore along the Mount Whaleback fault at Mount Whaleback. Compared to unaltered black shale from Wittenoom Gorge in the north and altered black and red shale at Mount Whaleback, reddish-green shale below the Mount Whaleback deposit is significantly enriched in MgO and CaO and depleted in SiO2. Samples of this shale consist predominantly of fine- to medium-grained dolomite and ankerite cut by chlorite and carbonate veins, contrasting with unaltered equivalents that contain mostly stilpnomelane, K-feldspar and relatively minor carbonates. This alteration is distinct from assemblages developed during regional metamorphism, and possibly represents hydrothermal alteration after metamorphism. Although several questions remain unanswered, these results support models that invoke an early hypogene stage during the formation of the martite-microplaty hematite deposits in the Hamersley Province.

Jan 1, 2005

By X Liu

The crystal chemistry of carbonate in Ca apatites, including Na-free and Na-bearing hydroxylapatite (CHAP) and Na-bearing fluorapatite (CFAP) and chlorapatite (CCLAP), has been investigated by Fourier transform infrared (FTIR) spectroscopy and single-crystal X-ray structure, using crystals synthesised from carbonate-rich melts at 1 GPa, 1400 - 1000¦C. The carbonate ion substitutes for both the X (OH, F, Cl) anion species in the apatite channel (type A carbonate) and the phosphate group (type B carbonate). The type A carbonate ion is oriented in the channel with two oxygen atoms close to the c-axis, and the type B carbonate ion is located close to the sloping faces of the substituted phosphate tetrahedron, with details varying with composition series. Sodium promotes the uptake of type B carbonate and also has a profound effect on FTIR spectra. Crystal compositions correspond approximately to the substitution formula Ca10-(y+z)Nay z[(PO4)6-(y+2z)(CO3)y+2z][X2-2x(CO3)x], with x + y up to 1.0 and z + 0.0 for CHAP, x + y + 4z + 0.4 for CCLAP, and x + y + 2z + 0.1 for CFAP, for equivalent conditions of synthesis. The sodium cation and A and B carbonate ion defects are locally coupled in all three composition series to facilitate charge compensation and minimise the effects of spatial accommodation. Synthetic Na-bearing type A-B CHAP with x + y + 0.5 has a similar chemical composition and FTIR spectrum to biological apatite.

Jan 1, 2008

Carbonatites - igneous carbonate-silicate rocks - host the world&apos;s major resources for niobium, phosphorous and REE (rare earth elements).Carbonatites represent the least common products of mantle and igneous processes and their emplacement is principally controlled by lithospheric domes and rift structures. Intrusive carbonatites frequently comprise carbonate-amphibole-apatite-pyrocWore assemblages, occur as plugs, cores, dykes, sills sheets, veins, pipes and irregular bodies, are gecichemically anomalous (Ba, Ca, Cl, F, Hf, Mg, Nb, P, REE, S, Sc, SO4, Sri Tb, Ti, D, V, Zr), are associated with alkaline silica-undersaturated igneous rocks forming carbonatite complexes, and display large, intensive alteration haloes. Also carbonatites are similar to limestones, prone to weathering, and may form thick laterite profiles.Magmatic ores (pyrocWore, apatite, bastnaesite, monazite, magnetite, baddeleyite, phlogopite, fluorite, calcite) and weathering related residual and supergene ores (pyrochlore, apatite, magnetite, anatase, vermiculite) are currently being mined on all continents except Australia. Australia is underexplored for carbonatite associated primary magmatic and especially residual-supergene ore deposits. Chances are very high for the finding of new carbonatite, occurrences and associated ores.

Jan 1, 1994

Carbothermal Reduction and Nitridation of Ilmenite Concentrates and Chlorination of the Reduced Samples

Sep 13, 2010

Carbothermal Reduction of Ilmenite Concentrates and Synthetic Rutile in Different Gas Atmospheres

Sep 13, 2010