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By Healy T. W, Dixon D. R

The present study 'of pure ZnS and NiS and ZnS (marmatite) by detailed electrokinetic methods has shown that by careful control of experimental parameters much new' information on sulphide-water interfaces can be obtained. Time-dependent processes of alteration of sulphide surfaces are foHowed by electrokinetic methods and indicate that the isoelectric point of the surface depends on elemental sulphur coverage, oxidation product coverage, and the conditions which promote or minimize such reaotions in the presence and absence of activator.

Jan 1, 1977

By King E. J

Department of Pathology, British Post-graduate Medical School, London:The experiments here recorded were devised and carried -out during the last two years in an attempt to corroborate the important work of Denny, Robson and Irwin (1939) in which they found that experimental silicosis could be prevented by means of metallic aluminum. By causing rabbits to inhale powdered quartz for several months they induced experimental silicosis. These animals then served as controls for comparison with another group which were dusted with a mixture of quartz and aluminum. In the second group silicosis failed to develop.Our experimental procedure was somewhat different. We resorted to intratracheal insufflation instead of simple inhalation, and we used rats instead of rabbits: otherwise the essential features of the original experiments were carefully duplicated.EXPERIMENTAL PROCEDURES.A single dose of dust was delivered into the lungs of each animal. The dust was suspended in a fluid medium and injected by means of a syringe directly into the trachea in known quantity (technique of Kettle and Hilton, 1932). The suspensions were autoclaved before use and were injected with aseptic precautions. Having had a long experience of this technique we employed it with confidence and usually secured a fairly uniform dispersal of dust throughout both lungs. To carry out injections successfully one requires, above all, an even suspension of dust which will flow smoothly and quickly from the syringe. This is not difficult in the case of quartz, for, though it tends to settle out rather quickly, this can be avoided by constantly agitating the suspension. The syringe containing the inoculum may be shaken gently right up to the moment of injection and then emptied quickly to prevent sedimentation. Powdered aluminum is more difficult to handle, for the particles tend to flocculate and are not readily made to disperse evenly in saline, even by violent shaking. For this reason an emulsifying agent may be used to advantage, provided it does not complicate the experiment, a point to be mentioned again presently.THE EXPERIMENTSExperiments with quartz alone: Extensive silicotic lesions were produced in 23 out of 26 rats by the administration of pure quartz dust in doses of from 50 to 200 mg. per rat. The dust was so finely pulverised that the particles averaged about 1-p. in size: none was larger than 5 p. and 99 per cent. were under 2.5 p.Eight of these animals survived for seven months and were then killed...

Jan 1, 1945

By Cocquio D. S, Bauchau C

In the course of an integrated airborne survey in 1975, a uranium-molybdenum deposit was discovered by Minatome Australia Pty Limited in North Queensland, Australia, approximately 70 km by road west of Townsville.The mineralization occurs in a welded tuff unit within the Carboniferous St James Vokanics. It is structurally controlled by a complex of subvertical east-west fractures and is exposed over a strike length of 350 m. Drilling has traced a further 150 m extension underneath a barren capping consisting of a thick pile of vokano-sediments. The maximum width of the orebody is 150 m, and its vertical thickness is approximately 100 m.The primary ore minerals are coffinite, pitchblende and molybdenite, accompanied by various alteration products (particularly uranium molybdates).The vein-type mineralization is considered epigenetic.A comprehensive program of surface drilling and underground exploration is in progress to establish the uranium and molybdenum reserves.

Jan 1, 1980

In his account of the Thackaringa sulphide ore, Lawrence (p. 92) reports the presence of valleriite as a minor accessory in chalcopyrite. He says that it is readily identified by its intensive anisotrophy and reflection pleochroism. He also gives (p. 87) the chemical formula as Cu8Fe4S7 Recent work by Evans et al. (1964), Chamberlain and Delabio (1965), and Schidlowski and Otteman (1966) suggests that most material identified as valleriite is, in fact, mackinawite. Mackinawite and valleriite are both extremely anisotropic and strongly reflection pleochroic, and so with fine-grained material it would be hard to distinguish them optically.Mackinawite, according to Evans et al. (p. D66) is a copper-free iron sulphide (PeS) with small quantities of nickel, whereas valleriite is considered to be a dimorph of chalcopyrite (CuPeS2 ). They found that mackinawite is much more widespread than valleriite, and, unlike the latter mineral, is commonly included in other sulphides, particularly chalcopyrite.Lawrence (p. 92) states that the valleriite inclusions are up to 0·01 mm long, so that an electron probe microanalysis should be quite feasible and provide a ready answer to this query.L. J. Lawrence: I thank Dr Townend for his comments on the occurrence of a valleriite-like mineral embedded in chalcopyrite from Thackaringa. The problem of distinguishing valleriite from mackina...

Jan 1, 1967

A new gold cyanidation assay technique has been proven for a range of ores, where it has demonstrated benefits of being: ò Accurate (reduces the typical range of assay scatter almost three-fold, and avoids common fire assay interferences). ò Fast (under one hour, providing a quantum shift in space requirement and equipment utilisation each bottle roll can provide over 15 determinations per day). ò Simple (suitable for field application, no high skill or experience requirements). ò Profitable (reduced drilling, drilling time, ore misclassification and/or double handling after mining). ò Cheap (far lower cost than Fire or Aqua Regia Assays, ie LeachWELLTM costs around 10ó for a 20 g sample at 50 per cent solids, proportionately greater for larger samples eg $1 for 200 g samples which address most nugget effect problems). ò Relevant (distinguishes economic. ie cyanide-extractable gold, the only unequivocal value to use for true resource definition, mine planning and grade control). ò Robust (rough bucket chemistry of samplers does not seriously affect results). A new development is the provision of LeachWELLTM CAS, a solution, which also contains optimum cyanide and stabiliser concentrations; and offers greater: ò Safety (the dilute cyanide solutions are stabilised to avoid generating toxic HCN vapours; and present no cyanide dust or flying chips to deal with). ò Ease (a single squirt dispenses precise quantities of the entire reagent suite, avoiding multiple weighings). ò Reduction in total reagent costs. An inter-laboratory comparison on nine ore types, using two assay techniques (Fire Assay and Aqua Regia) involving 45 laboratories, has demonstrated that LeachWELLTM 60X assays for the samples tested, were equally or more reliable than typical Fire or Aqua Regia Assays. There is particularly great benefit in applying LeachWELLTM 60X assays to richer ores in comparison to Aqua Regia assays, which appear to be prone to very significant underassaying depending on individual analyst skills, and which often suffer greater nugget effects. The major impacts for heap leaching are that: ò Using the LeachWELLTM assay technique for grade control, ore of marginal grade is not accidentally discarded to waste or visa versa due to the scatter of assay data inherent in typical small charge (25 g) fire assays. ò LeachWELLTM assays very importantly report only that gold which will be recoverable in the heap, viz that which is liberated - an important factor where the coarse crush often leaves ten per cent of gold unliberated. These impacts are of particular importance for many ores (ie most of those recovered from open pit operations and at the margins of rich ore subject to slurry processing) subjected to heap leaching as the oxide zones often present major problems of nugget effects as well as mineralisation that cannot be accurately assigned through interpretation of clear structural controls.

Jan 1, 1994

Platinum-group minerals (PGM) are recorded from a number of localities along theWaiau River, western Southland, and the south coast of the South Island, New Zealand. At each locality, small amounts of PGMs were recovered as by-products of historical gold mining operations. During the period 1890-1950 an estimated 1000-2000 oz. of æplatinumÆ were recovered from the region, the only area within New Zealand where PGM have been commercially exploited. The PGM suite of southern New Zealand consists of Pt-Fe alloys, IPGE (iridium subgroup, platinum-group elements) alloys, sperrylite (PtAs2), cooperite (PtS) and braggite ((Pt,Pd)S). The composition of Pt-Fe alloy exhibits considerable variation and two compositional populations are recognised. Some Pt-Fe alloy grains are chemically zoned. Iridium is the most abundant IPGE alloy phase and often contains considerable Pt, in contrast to osmium and ruthenium alloys. Cooperite and braggite grains are characterised by extremely low concentrations of Ni.   Exsolution of osmium and iridium from Pt-Fe alloy and Pt-Fe alloy from iridium is observed Several PGM host mineral inclusions which vary from single to poly-phase, display rounded to equant outlines and range in diameter from greater than 100 ¦m to less than 5 ¦m. Olivine and Ni-sulphide inclusions are only present within IPGE alloys. Pt-Fe alloy, cooperite, braggite and sperrylite host Cu-Fe sulphides, a wide variety of PGM, clinopyroxene, amphibole, magnetite and plagioclase within inclusions. Sperrylite also hosts Pd bismuthiotellurides, gold and several potassium-rich silicate phases. Similarities in inclusion phases and mineral chemistry from several localities suggest that the PGM are derived from a single (as yet unidentified), probably calc-alkaline magmatic source. This source is situated somewhere along the margins of the western Southland sedimentary basin where PGM liberated by erosion are transported down the Waiau River and dispersed eastwards along the coast by strong longshore currents.

Jan 1, 1995

THE most important part of the routine survey work on a mine is the keeping up-to-date of plans and sections showing progress of stoping and development work, and the direction of the latter for the purpose of making necessary connections. Except in specialcircumstances, e.g., major horizoittal development, the exactitude required in this work is not extreme, and a method of survey in keeping with the demands of the work itself is all tbat is required.For example, no one would consider measuring the walls of a stope to a fraction of an inch; such extreme accuracy would be wasted.The stope walls being irregular, a mean is usually taken, and for ordinary purposes a survey with a limiting error of six inches is quite satisfactory for the purpose of plotting either stoping or development.It is the author's aim in this paper to describe the method in use at the North Broken Hill Oompany's British mine. This method, while being sufficiently accurate for the purpose in view, possesses the very great advantages of speed and simplicity of operation,with a minimum of necessary equipment. This latter is a very important item where several surveys on different levels have to be carried out on the one day.Let it be understood, however, that the use of this method does not dispense with the theodolite, but simply serves as a convenient adjunct to obtain details and to extend the accurate theodolite survey up rises and down winzes, and through ladderways orwinzes into stopes, where the use of a theodolite, if not actually impossible, is often exceedingly inconvenient. This is particularly so on the British mine, where a large proportion of the ore is won from narrow and complex-dipping lodes, and where vertical ore...

Jan 1, 1928

This paper is intended partly as a summary of the conclusions that have been arrived at by various authorities on this matter, and also with a view to initiate some discussion on the subject, especially as most of the quartz gold mines in Victoria are operated without having any proper assay plans or any idea of the real values other than those given by the mining managers, who, from experience in the particular cases, are supposed to be able to arrive at a correct idea of the true values of- the ore, and, in many cases, oppose any other methods than their own, holding the view that no sampling is equal in correctness to the bulk sample of the battery. The necessity of properly sampling and estimating the ore in a mine in every case, perhaps hardly needs to be urged on the members of the Institute, but is not, apparently, so obvious to others.It is proposed to confine this paper to the sampling of ore reserves in a mine, and the various points which have to be taken into consideration in arriving at values, from the assayer's point of view, leaving the methods of sampling metallurgical products out of consideration for the present. "It is advisable to define" ore reserves" as ore exposed on three sides at least, and accessible to the sampler on all three. "Prospective ore" would include all ore not so fully exposed; but which may, from the nature of the case, and the geological conditions prevailing, be reasonably supposed to exist.

Jan 1, 1904

IN previous discussions on the occurrence of gold in the Bendigo quartz reefs the opinion has been put forward that the gold shoots are primary concentrations in the quartz reefs during the period of vein-formation. The view has been based upon the constant features of the gold shoots in a large number of individual reefs, independent of their depth below the surface. These features include the mineral associations accompanying the gold, the appearance and association of the gold in the quartz, the similarity in all respects (excepting mineral content) between richly gold-bearing quartz and poor quartz, and the variations in mineral content in the reef apart from gold. The view has been supported by a relation of the gold shoots to faults, together with the dependence of the reefs on the existence of pre-mineral faulting. The secondary deposition of gold has only been observed in a few instances .associated with the younger monchiquite dykes, and is of no economic importance.

Jan 1, 1922

By M A. Mongillo

Most geophysical and geochemical data collected during regional exploration programmes are in vector form (location, value), and have traditionally been presented and interpreted in a profile or contour map format. However, the human vision system can interpret data presented in image format much more easily and new information is often revealed by the judicious application of powerful interactive computer image enhancement techniques. This paper describes a practical demonstration of the application of such tools to gravity and resistivity datasets from the Central Volcanic Region of theNorth Island.   Filtering, contrast enhancement, relief shading, pseudo-colouring and then overlaying of the gridded datasets in image format has helped identify inter-relationships such as the association between many low resistivity anomalies (epithermal deposits or geothermal resources) and the edges of large gravity anomalies (calderas or grabens). Similar revelations should result from the application of these tools to the integration of other mapped datasets from geophysical, geochemical and geological disciplines.

Jan 1, 1992

Generating short- and long-term mine production schedules in isolation and independently from each other means that only a local optimum can be achieved when each scheduling phase is carried out. The globally optimal solution however, can be achieved when integrating scheduling phases and accounting for the interaction between short-term and long-term activities simultaneously. This paper addresses the task of integrating short- and long-term production plans by combining the short-term objective of minimising deviation to targeted mill feed grade with the long-term objective of maximising net present value (NPV) into a single mathematical model. A case study is presented which compares the present values of the same stope data set scheduled via separate long and short-term models and than by the proposed integrated model which applies a predetermined penalty for each tonne of metal deviation to target for the respective ore tonnage being processed. This allows an operation to obtain a globally optimal scheduling regime when taking into consideration the cost and loss of value resulting from fluctuations in grade to the mill over the short-term.

Dec 6, 2010

IN the underground department of a mine, we may fairly say that "good management is based upon three elementals: first, sound engineering; second, proper coordination and efficiency of every human unit; third, economy in the purchase and consumption: of supplies.This paper is practically an analysis of the second element; which stands out prominently as the most important in the winning of successful results. The human units are divided into officers and men. The officers intermesh. One man takes responsibility where another throws it down; incessantly new conditions are arising where they may be doubtful of their powers; and always, on account of the three shifts, varying methods of work are coming into conflict. This very often results in disorganization. What is most necessary to guard against this is an esprit de corps, which would influence officers to stifle personal feelings for the general welfare of the department, To secure co-operation and loyalty of the staff, the writer recommends for the mines of the field a system of profit-sharing. Distributed on a salary basis, together with liberal holidays (not less than three weeks in each year) on full pay...

Jan 1, 1912

The objectives of this paper are to introduce the International Code of Practice for Risk Management of Tunnel Works and to illustrate to the participants of the 13th Australian Tunnelling Conference 2008 how the insurance industry would like to see the future of tunnelling insurance. Tunnel construction projects have suffered large losses over the years as can be shown from various loss examples and a list of major losses over the last ten to 15 years. Since the consequences of insufficient risk control had to be borne by insurers, these losses have heightened the need for improved and adequate risk management measures so that insurance cover can also in future be provided for this hazardous industry sector. Observations are made as regards to the prevailing trends in the tunnelling industry, which contribute to the increase in risk and have adverse consequences for the insurance industry. To find a solution to this dilemma various options are examined with the suggestion of a Joint Code of Practice for Tunnel Works being agreed by all stakeholders, which would become essential to secure future insurance protection for such project work. The British Tunnelling Society has, in cooperation with the Association of British Insurers, developed such a code, which the International Tunnelling Insurance Group has now adopted for global application in international markets. The content and concept of this code is explained to establish a framework of understanding and applied risk management principles for tunnel works. This initiative also has the support of the International Tunnelling Association and the International Association of Engineering Insurers. The international application of this new code is demonstrated with a few examples, which also includes Australian projects. It is the aim that this code forms in future part of the insurance coverage for tunnelling works in order to put this risk segment on a more sustainable basis. For that reason the insurance industry is seeking the support of all stakeholders of tunnelling construction projects.

Jan 1, 2008

Early strategic mine planning includes decisions over the organisation of work and workforce accommodation. These decisions involve significant commitments that affect not only employee quality of life but also the impacts and relationships with existing local communities. Strategies for workforce accommodation are characteristically community-based (either as purpose-built company towns or integrated within existing local communities) or commuter (fly-in, fly-out) mine camps. The quality of accommodation underpins the fulfilment, morale and motivation of employees. This is not only relevant to productivity and safety, but also to recruitment and retention, particularly with the current onset of a significant human resources crisis. In the event that communities exist in proximity to a proposed mine then the accommodation strategy selected can influence the value-adding potential for the sustainable development of such communities. This early planning is particularly challenging where mine locations are isolated and/or face significant economic, social and political adversity. This paper draws upon a case study review of five large mining projects implemented in three South American countries, selected to cover a range of scenarios and accommodation strategies. The review aims to advance our understanding of the complexity of the underlying planning issues. Each scenario considered the prevailing environmental, social, economic and political situation, together with the adopted accommodation strategy. The case study review aimed to identify lessons learned and to make recommendations for advancing mineworkersÆ accommodation planning practice.

Jan 1, 2006

Marble deposits of dolomitic variety are available in large quantities in India and for extracting these deposits diamond wire saw cutting machine is mainly used. Cutting performance of the diamond wire saw machine depends on rock parameters, machine parameters and operational parameters. Rock parameters related to physico-mechanical properties, such as, compressive strength, tensile strength, shear strength, modulus of elasticity and abrasion resistance of marble play role in determining cutting rate and beads wear rate. Thus, this study was undertaken to determine the relationship between different physico-mechanical properties and cutting performance. This work also aimed at enhancing the cutting performance of diamond wire saw in dolomitic marble deposit. Study was conducted in the field at three different zones having deposit of soft, medium hard and hard dolomitic marble. During the study, cutting rates and wearing of diamond beads were recorded in the field. Physico-mechanical properties were determined in the laboratory. The results obtained were subsequently evaluated by using statistical analysis. Study revealed that these properties of marble play a significant role in the performance of diamond wire saw machine. Predictive equations for the wearing of diamond beads and cutting rate were developed based on regression models. Results of this study will be of ample use for operators of wire saw to achieve maximum cutting performance and for manufacturers in designing the diamond beads.

Dec 6, 2010

Holla has given a good background to the various methods of subsidence control in the coalfields around Sydney.The present writer notes that in many cases, especially with wide longwall panels, there is not the flexibility to alter the mine layout as there is to some degree with the various pillar extraction methods. For this reason it may not be possible to plan the workings to minimise subsidence and some damage to structures may occur. The cost of repair or the cost of subsidence provisions to minimise damage may be small in relation to the tonnages of coal which would otherwise have to be sterilised. One method of subsidence control which has been in use in the Newcastle area since 1970 is the panel and pillar layout (partial extraction layouts with stable pillars). An extracted panel width of 0.6 times the depth of cover resulted in a maximum subsidence of 115 mm for an extracted seam thickness of 2.2 m.As Holla points out, the extracted panel widths in relation to th depth of cover depend on the particular geological setting. His Fig. 3 shows that the subsidence over a panel width of 0.3 times the cover depth in the Southern Coalfield is the same as over a panel width of 0.55 to 0.6 times the cover depth in the Northern Coalfield.Selective pillar extraction and longwall mining can both be used in the panel and pillar layout. Holla's Figs 2 and 3 are used to estimate the maximum subsidence over an extracted panel of known geometry. Maximum subsidence is related to seam thickness. What provision is made for a reduction in subsidence due to the coal which remains behind in a pillar extraction panel if the pillar recovery is poor? The writer suggests that an effective seam height could be used, based on the actual mining height reduced by a factor to account for the percentage recovery of coal from an extracted panel.

Jan 1, 1986

By G Ma, L Qi, J G. Shellnutt

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. The Emeishan large igneous province (ELIP) of SW China is host to magmatic Ni–Cu–(PGE) sulfide and Fe–Ti–V oxide deposits which contain economic to subeconomic concentrations of precious and base metals. The formation of a given deposit-type (ie sulfide versus oxide) is thought to be related to the type of parental magma (ie high-Ti versus low-Ti) and the subsequent processes (ie fractional crystallisation and sulfide segregation), which allowed for metal enrichment.We examined the PGE of Baima and Taihe oxide-bearing layered mafic intrusions from the ELIP (Shellnutt, Ma and Qi, in press), and compared them with the nearby Xinjie and Hongge intrusions as well as with the Emeishan flood basalts. The PGE results for the two intrusions are contrasting. The Baima gabbroic rocks are almost PGE-barren (SPGE < 4 ppb) whereas the Taihe gabbroic rocks are variable, but generally much higher in PGE concentrations (SPGE < 2 to ~300 ppb), although the gabbros from both intrusions are enriched in platinum-subgroup PGE (PPGE = Rh, Pt and Pd) relative to iridium-subgroup PGE (IPGE = Os, Ir and Ru). Cu/Zr, Ni/Ir, Y/Pt, Cu/Pd and Ni/Ir systematics suggest that the Baima rocks were derived from a relatively evolved, mafic, S-undersaturated parental magma that was affected by earlier sulfide segregation. In contrast, the Taihe rocks record evidence of both S-saturated and S-undersaturated conditions and that the parental magma was likely emplaced very close to S-saturation. Through comparison of the PGE contents in the Emeishan flood basalts and the Emeishan oxide-bearing intrusions, we provide a self-consistent model for ELIP that the PGE budget in a magma is not strictly controlled by magma series (high-Ti versus low-Ti), but very much by crustal contamination.CITATION:Ma, G, Shellnutt, J G and Qi, L, 2015. Platinum group elements in the Baima and Taihe Fe-Ti oxide-bearing gabbroic intrusions of emeishan large igneous province and problems on propensity of magma series for sulfide- versus oxide-dominated deposit types, in Proceedings PACRIM 2015 Congress, pp 303–310 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

The subject which I have chosen for my paper is one that I am sure has occurred to the minds of nearly every mining man on these goldfields at some time or other. I refer to the carrying out of hydraulic mining on a fairly large scale on some ofthe alluvial areas of the West Australian goldfields. There are many, no doubt, who have the question ready at the present moment, "But where is the water coming from? " However, the great difficulties in the way are not due to the want of natural facilities, but due to the fact that sufficiently large areas cannot be leased for this purpose under the present Mining Act. Now, ever since the inception of the West Australian goldfields there has been the old familiar cry when referring to some alluvial gully or flat, "I wish I had a head of water to sluice that ground," but what seems an impossibility at times can be brought to a very great possibility by the use of a little thought and the expenditure of the necessary capital. This is so as regards West Australia with sluicing which, in spite of the its having so many detractors, can be carried out successfully in certain localities if the ordinary facilities on the part of the Govenment are given, and on the other hand the necessary capital is supplied. Alluvial gold areas, I propose now to draw your attention to first of all, the numerous alluvial areas that exist around Coolgardie, Kalgoorlie, Bulong, Kurnalpi and many other centres. Some of these areas have afforded fortunes inthe early days to the alluvial miner, and also afforded a living for years to many diggers' by the use of the dryblowing...

Jan 1, 1901

By J Pric, M Fulton, C Xia

A cyanidation study was conducted on a mild refractory gold ore sample from the Central zone of Clarence Stream Property, owned by Freewest Resources Canada, to develop a leaching strategy to extract gold. Gold, at a grade of 8.00 g/t, is present as native gold, electrum and aurostibite. The ore also contains 2.8 per cent pyrrhotite, together with several antimony minerals (0.8 per cent berthierite and gudmundite, 0.18 per cent native antimony and stibnite). It also exhibits weak preg-robbing properties with 0.16 per cent organic carbon. Aurostibite, a gold antimony compound, is particularly known to be insoluble in cyanide solution. The antimony dissolves in cyanide solution to form antimonates, which retards gold dissolution. Industrial practice of extracting gold from aurostibite generally consists of producing a flotation concentrate, which is leached in a pipe reactor at low alkalinity and high oxygen pressure with about 20 g/L cyanide. The proposed new approach is efficient and allows the extraction of gold directly from an ore at atmospheric pressure and a low cyanide concentration at pH 10.5. The effects of grinding, pretreatment, lead nitrate, kerosene and cyanide concentrations have been investigated. The maximum gold extraction obtained on the ore was 87.9 per cent using 800 ppm NaCN, 500 g/t lead nitrate, 30 g/t kerosene, DO 10 ppm and pH 10.5 in 168 hours. The associated cyanide consumption was 1.3 kg/t. The additions of lead nitrate and kerosene increased gold extraction. In comparison to a P80 of 74 ¦m, a P80 of 30 ¦m significantly increased gold extraction. Gold in solid solution in gudmundite and arsenopyrite was believed to be responsible for the unleached fraction until mineralogical analysis of hydroseparation concentrates of leach residues showed that most of the unleached gold occurs as aurostibite, either as locked grains in sulfides/sulfarsenides or as grains with passivation rims of an Au-Sb-O phase. Coarse gold was also found. Gold extraction was not sensitive to cyanide concentration from 250 ppm to 1200 ppm NaCN and high pH was detrimental. Decreasing the cyanide concentration reduced the cyanide consumption to 0.85 kg/t. The removal of coarse gold using a Knelson concentrator and a Mosley table prior to leaching increased the gold extraction to 90.4 per cent (leach residue at 0.77 g/t).

Jan 1, 2007

By M Hourn, G Anderson, V Lawson, P Voigt, D Mallah

As mine head grades decline and orebodies become more complex, traditional mineral processing techniques and flow sheets to achieve saleable concentrate become more difficult to design and construct. Mines with lower quality concentrates or concentrates with penalty elements are particularly under threat. The economics of such operations are far more susceptible to metal price fluctuations, concentrate treatment terms and the availability of other, cleaner concentrates. Additional value may be realised for these orebodies through improved recovery by producing a low grade middling concentrate for further processing, in conjunction with a saleable concentrate.The most economic effective way to reduce impurity levels is to do so as early as possible in the mining value chain. Technologies such as fine grinding and fine particle flotation are well established as effective methods for impurity rejection in mineral processing. What is often overlooked is how a hydrometallurgical process could also be integrated in the overall flow sheet to achieve higher overall recovery at the mill. In the base metals environment, this is probably because hydrometallurgical processes are associated with production of metal, or require the use of expensive and toxic precipitating agents once the minerals of interest are in solution. These processes can be very expensive, particularly with rising power costs and poor economies of scale in capital costs associated with low production rates from middling streams. Glencore Technology (GT) has recent experience in the treatment of middling and low grade concentrate streams and also tailings streams to complement a concentrator flow sheet in a refractory gold and base metals setting. The value proposition is the isolation of a low grade middling concentrate from the primary circuit or the tailings stream for upgrading to an intermediate product with an equal or higher grade than the primary concentrate to allow blending for sale. This allows the plant to operate on a more favourable part of the grade-recovery curve while avoiding the expense of metal production. For existing operations this is particularly attractive since it can be added to the flow sheet with no process interruptions. Two case studies are examined showing flow sheets and costings to arrive at the value proposition of the GT low grade treatment flow sheet.CITATION:Voigt, P, Hourn, M, Lawson, V, Anderson, G and Mallah, D, 2017. Economic recovery and upgrade of metals from middling and tailing streams, in Proceedings MetPlant 2017, pp 289–297 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 11, 2017