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Silver and gold bearing ore from the Palmarejo mine, located within the Mexican state of Chihuahua, contains a complex mix of electrum, native silver, silver sulfides and silver chlorides. This paper presents a case study that describes the selection, development and engineering of a tailored process plant for the recovery of silver and gold from this ore. Process circuit feasibility study modelling, metallurgical test work and engineering studies are outlined. Options considered to optimise the recovery of the contained silver and gold are compared, based upon cost, operability, recovery and engineering aspects. Concentration by flotation was found to be the preferred primary recovery route. Intensive leaching of the flotation concentrate resulted in solution grades sufficient to allow direct electrowinning to be evaluated against the more traditional Merrill Crowe process. The flotation tailings stream is processed through a separate leaching stage as there is sufficient economic metal extractable from this stream. The processing flow sheet, which is designed to maximise the recovery from both the flotation concentrate and tailings, and to utilise a common metal production facility, is presented.

Jan 1, 2009

By A Williamson

The New South Wales Department of Mineral Resources objective is to use data and information to undertake a detailed analysis of incidents and accidents to identify risks so that the predictable can be foreseen and avoided. The Department of Mineral Resources has established a computerised database called COMET (COmmon Mines EnvironmenT) to capture information on accidents incidents, inspections, audits and accreditation in improving safety and environment performance. This data together with data from Coal Mines Insurance and WorkCover NSW is being used to provide trend and comparison information. The NSW Injury Risk Management Research Centre at the University of NSW has been engaged by the Department to collate and prepare a detailed analysis of the data. Through this process, five areas have been identified for further research. These being: electrical energy, mechanical equipment, work environment, hours of work, and contractors involvement accident and incidents. The paper covers: the establishment of a mix of performance measures for the industry to indicate whether the safety performance is improving; the provision of data to provide useful comparisons and benchmarks against which companies can compare performance; the development of positive performance measures; the findings and outcomes of the detailed analysis of electrical energy; shocks; the provision of information to industry; an outline how the data is being used to determine departmental; operational priorities; and future plans to undertake research into the other areas identified.

Jan 1, 2003

Using a Jarrell-Ash "Compact" direct reading spectrometer, analyses were made of a wide variety of rocks ranging from acidic to ultrabasic types. Statistical evaluation suggests that accuracies comparable with the values obtained by the rapid chemical methods used by the United States Geological Survey will be obtained.The spectrographic method involves fusion of the rock with lithium tetraborate, strontium being incorporated in the flux as the internal standard. The resulting bead is ground with graphite and pressed into a pellet. The counts obtained on two standard pellets are used to correct for instrumental drift.Background readings are made at 4109 Å and corrections for background are made to all lines. Corrections for matrix interferences, both by chemical suppression and optical enhancement, are made. The three corrections of drift, background, and matrix are incorporated into one general expression which has been programmed on magnetic cards, each element requiring a separate card. The cards are placed individually into a desk top computer (an Olivetti Programma 101), which enables true counts to be calculated from the "readout" counts, and the element concentration is then obtained from computer-printed tables by referring to the appropriate value of true counts versus concentration. These tables were prepared by making a polynomial regression analysis of the spectrographic results from 50 standard and analysed samples, a curve of best fit being chosen for each element.The regression coefficients, usually of a fourth or fifth degree equation, together with other relevant data, were fed into a large computer, programmed to print out tables of concentration versus true counts. This technique enables the results obtained to be based on mathematically-derived values rather than on hand-drawn calibration graphs, giving greater inherent accuracy. The technique has been shown to give results of good accuracy and acceptable precision suitable for many geological and geochemical exploration programmes involving the analysis of many rock samples of different types.

Jan 1, 1969

By R Vleggaar

In addressing a short-term operational need for the relocation of a tailings storage facility reclaim pond, a mine has achieved a host of water management objectives. Through effective planning and adoption of a strategic æwhole of mine lifeÆ approach, the mine has achieved significant environmental, social and economic benefits. A review of all water management aspects across the site identified a host of other interrelated water issues and concerns which, if dealt with individually, would prove too costly for individual operational departments. When considered as a whole, however, the issues became opportunities and provided the stimulus for integration of the site water management system. The development of site water and solute balance models provided the tool by which a number of water management options/strategies could be evaluated. The conceptual design and costing of the proposed water infrastructure further facilitated the evaluation of the multiple benefits to be gained from each option. A business case could then be made to mine management for the preferred option. The recommended water management strategy finally recommended to the mine not only provided a tailings storage facility (TSF) reclaim pond, but also provided for:increased wastewater recovery from the TSF, the capture of all waste rock dump run-off, additional water harvesting from local creeks, increased wastewater reuse, improved environmental water management, infrastructure that could be used by the local community after mine closure, and overall cost savings. This paper illustrates how effective water management planning can provide both short-term economic and environmental benefits, as well as long-term social benefits.

Jan 1, 2006

By Rubisov DH

This paper is related to the problems of the mathematical modelling of vibrating screening process and to predicting the screening operation results. The authors propose a model of screening based on the interpretation of granular material segregation on a screen surface as an instantaneous process. Results show an agreement with laboratory and pilot plant tests. Derived formulae can be used for screen sizing and screening result estimating.

Jan 1, 1993

By Davies B, Rogers A, Grainger A, Todd J, Brenman R, Jones L, Horton B, Eager L

Research into the control of diesel particulates (DP) has been. conducted by BHP Coal for more than 7 years. Personal monitoring of employee exposures (n = 480 full shift samples) conducted at nine underground coal mines has indicated that the exposure of the workforce ranges from less than 0.1 to 2.2 mg/m3 of DP dependent on job type and mining operation. Approximately 50% of the mass of DP captured is elemental carbon (EC) which is the species currently being considered by some international regulatory authorities as the exposure standard. Five technologies for controlling DP were investigated in a combination of studies conducted in an above ground simulated tunnel, in a special controlled section of underground mine roadway and validated by application in standard coal mining operations at Tower Colliery. Tests conducted under controlled conditions indicate that dependent on the type of fuel in use, the introduction of low sulphur fuels can reduce DP levels in return airways by up to 50% and in actual mining situations a reduction of 20% can be achieved in exposure of the workforce. In addition, subjective responses from the workforce indicate that exhaust emissions from low sulphur fuels provide lower irritation and a more pleasant aroma. The use of water filled scrubber tanks reduces the level of DP emissions by 25%. Chemical decoking of engines resulted in a reduction of 20% in DP in return airways. A commercially available non-flammable disposable dry exhaust filter constructed from synthetic organic fibres with an operational lifetime in excess of 20 hours was found to reduce DP exhaust emissions by 80%. Investigations have indicated that the use of increased ventilation to control DP levels particularly in multiple vehicle situations does not follow a simple dilution factor and in some instances compliance with current regulatory requirements may not produce the required reduced exposure levels. The results from single component control strategies provide considerable reduction in exposure to DP, however the most efficient and cost effective control methodology is the use of a combination of individual systems modelled to operations conducted at each mine.

Jan 1, 1998

In the sixteenth century the Spanish Captain da Alvaro Soavedaro, on a search for the explorer Ferdinand Magellan, came across the main island of New Guinea which he named Isla del Oro (Island of Gold). Since that time exploration for, and mining of, gold has been pursued by many, culminating in . the development of major world-class projects in the latter part of the 20th century. Though various prospectors have panned for gold and small gold mining projects were undertaken through the seventeenth and eighteenth centuries, it was not until the 1880's when mining became a more concerted economic venture. Misima and Woodlark Islands in Milne Bay, Gura-Ackera and Yoada in Oro, and Lakekamu in Gulf Province and Keveri in Central Province were all gold producers by late nineteenth century. It was in the 1920's that corporations began mining in PNG and with the commencement of production at Panguna in Bougainville in 1972 a new era of mega-project mining began.' Today there are two large mining projects producing mainly gold and copper. The first, already mentioned, is Panguna on Bougainville Island. This project has provided Government with $US 475 million in taxes. ok Tedi is the second large mine development located in Western Province. It began production in 1984 with the extraction of the deposit's "gold Cap".

Jan 1, 1987

In a previous paper in these Proceedings(l) it was shown from a study of the bore'logs and analyses then available, that the brown coal seams of the Latrobe Valley areas show progressive changes in composition with increase of stratigraphic depth, equivalent to a rise in rank: These changes appear as:(i) An increase in ultimate carbon and hydrogen, calculated on a dry, ash-free basis, and(ii) An increase in calorific value, calculated on the, same basis, each of the order of 1% per 100 ft. of depth, and(iii) A decrease in moisture content of the order of 0.5% to 1.0% per 100 ft. of depth. The decrease in moisture content was found to be less regular than the other changes. In some bores the moisture content remained more or less constant throughout a single seam, or fluctuated slightly, decreasing stepwise on passage to the seam below.It was noted that individual analyses within a bore showed irregular fluctuations, tending to mask the general trend in composition change. This was particularly so for the moisture content, which had been determined for 10 ft. lengths of core, whereas the other components were determined for 50 ft. lengths of core. Averaging of the moisture contents over 50 ft. lengths reduced the masking effects of these irregularities. The suggestion was made that these irregularities arose from variations in the relative proportions of pollen, resin, wood (lignite) and woody attritus composing the core. Such variation in the coal seams has since been established in some detail for the...

Jan 1, 1948

In Australia we usually define "resource" in purely material terms, and rarely relate it to intellect and human capacity. We look at the sheer abundance of our natural resources and are satisfied with the feeling that we don't really need-to rely on using our brains. Certainly our country is fortunate to have the mineral resources it does, but in many ways Australia's worst enemy is its "lucky country" syndrome because we tend to underutilise the great resource we have in the capacities of our people. Raw material exports will undoubtedly continue to contribute a major share of our export revenue, but to harness the riches our country has to offer most effectively we need the vision and planning necessary to bring together our material and human resources. There is a need not only to find, exploit and process our minerals economically, but to turn as much of our mineral wealth as possible into high value products before it leaves the country. In particular we must use our brainpower if we want to maximise economic benefit from and political influence over the strategic minerals which leave our shores. In the past we have been successful in finding and exploiting minerals because our mining industry has been in the forefront of private sector research and development. But if Australia is to have an advantage over other mineral rich countries in insulating itself from the effects of cyclical swings in commodity prices, then the future of the industry must lie even more in technological sophistication rather than depending. on such considerations as size and location of mineral deposits. To survive, our mineral industry must have the foresight and resourcefulness to make its own luck. There are two keys to increased efficiency in exploration and production and in further processing methods: enhancement of the skills of the workforce and continual improvement of R&D.

Jan 1, 1986

Felspar occurs in association with quartz in the Broken Hill lode pegmatites and is brilliant green, greenish white, and white in colour. The pegmatites occur mainly in the walls in sporadic patches, parallel to the general dip of the ore deposit. The occurrences are of no economic value.Deposits of marketable felspar occur in pegmatite in a number of localities around Broken Hill, New South Wales.The majority of these are in the form of an irregular outcrop, usually of tapering length and depth. The maximum depth of any deposit yet worked in the district is about 40 ft. The felspar is occasionally contaminated by "blows" of quartz, mica and beryl, but the two latter are profitably marketable when separated.Felspars vary in colour from pink, through grey to snow white, and the colour is not indicative of the mineral content. The largest deposit at present being worked is the Egebeck quarry, about 14 miles south of Cockburn. It is a prominent outcrop, roughly circular and about 150 ft. in diameter, covered by one to three feet of overburden.The felspar is mainly massive, but contains some cleavage planes at approximately 90°. Intrusions of quartz and mica occur in patches, but the deposit appears likely to improve in size, regularity and quality below the present working floor.COMMERCIAL USES.Commercial felspars are mainly used in the ceramic industry, for which a high-grade potash felspar is required.The dental industry requires limited amounts of soda felspar with a very low Fe20s content. The poorer grades...

Jan 1, 1946

By J C. Diaz, C R. Scherpenisse

Blasting represents one of the most relevant unit operations in the process of mineral extraction. The final objective of this operation is that of obtaining an adequate final fragment size distribution such that the combined costs of drilling, blasting, excavation and transport, and crushing/grinding, are minimised, while at the same time producing the minimum possible level of damage to the surrounding rock mass. The strong influence that drilling and blasting has over the subsequent processes involved in the operational cycle makes it imminently desirable to have access to experience and technology which make possible the evaluation and optimisation of this unit operation. The correct use of vibration monitoring techniques offers a number of benefits in terms of their ability to examine any blasting process in detail. In effect, the measurement of particle velocity levels that result from the detonation of each explosive charge offers a means by which it is possible to measure relative efficiency of each charge, interactions (productive and counterproductive) between adjacent charges, and a definitive indication of general performance of any given blast design and its implementation. In this way the monitoring of blast vibrations in rock due to the blast event, can be used as a diagnostic tool, given that the correct interpretation of the vibration traces allows the determination of the level of interaction between the design and operational variables of the blast event. This makes it possible to evaluate, for example, the presence of out of sequence detonations, statistical scatter in the detonation times of pyrotechnic delay detonators, deficient detonation of charges, instantaneous detonation of charges and sympathetic detonation of charges, as well as the general of vibration levels in terms of peak particle velocity, acceleration, and displacement. Another important use of such data is in the construction of a database relating vibration levels to charge weight, hole diameter, and distance, for any given rock type, enables the calibration of predictive vibration models which in turn make it possible to predict the damaging effects of blasting. Knowledge of both the vibration levels induced, combined with quantitative measures of the geomechanical competence of a rock mass make it possible to estimate the probability of producing blast induced damage. The high levels of vibration generated by some blast events may damage the rock mass, producing new fractures or extending and dilating existing fractures. The vibration in this context may be considered as a dynamic stress provoking strain in the rock mass. This paper describes the application of the vibration monitoring technique, particularly in the underground mining environment, and its importance in diagnosis, modelling, control, and optimisation of the development blasting process. The potential of the technique is assessed in the context of achieving substantial techno-economic improvements development blasting results, increasing output whilst minimising the operational costs of the mining process.

Jan 1, 1999

Australian wheat belt agriculture is causing a decline of its natural resource base. The major problem, salinity, arises from a small reduction in water consumption by agricultural crops compared to what prevailed under the prior native vegetation. This causes groundwater accumulation which, in the low relief landscapes of the wheat belt, is leading to extensive surface saturation in low landscape positions and dramatic, destructive change in the hydrological behaviour and habitat of streams and rivers. The ability of agriculture to invest in salinity control is severely limited by its long-term decline in its terms of trade. Extensive planting of perennial vegetation has the potential to increase water use and arrest the salinisation process. If these perennials were also commercially attractive, the cost of salinity treatment could be minimised. Given the difficult commercial position of food commodities, it is logical to develop ænon-foodÆ perennial crops, in particular woody crops suitable for industrial products. This paper looks at the example of Sweden, where there has been a generation of investment in developing forest harvest residue recovery, and short cycle woody crops for bioenergy, but with only limited success. In contrast, secondary residues (processing wastes) from forestry industry are readily saleable for low value uses like bioenergy. This suggests that the model woody crop must have a higher value fraction to facilitate delivery and commercial use of its lower value fractions. This model is being emulated in the development of native mallee eucalypts as short cycle woody crops in Western Australia. Some $50 million has been expended on mallee development in the past decade and this has culminated in an engineering demonstration of integrated processing. The putative high value products are activated carbon and eucalyptus oil and the residue (plus waste heat) will be converted to electricity. The potential scale on which crops of this type would be required to achieve salinity control means that many more high value and residue products will have to be developed. Metallurgical charcoal appears to be a promising product option.

Jan 1, 2006

This address was delivered at the Annual Conference Presidential Dinner held in Sydney on 11 July 1988.The Australasian Institute of Mining and Metallurgy brings together, voluntarily, people with a professional interest in the disciplines and skills which are employed in the mineral industry, and in relation to that industry.We come together because we have a mutual interest in improving what is done by the mineral industry, in all its aspects. It is this sense of continuing improvement, of doing better, of doing as well as we can, as our knowledge and skills improve, that unites us in creating and fostering a professional association of likeminded people.We know from our professional training and experience that enormous progress has been made, at an ever-increasing rate, in the mineral industry, particularly this century. We know that the mineral industry has played a very major role in providing the means by which so many more people survive to live longer, healthier ,and more interesting lives, than ever before. Indeed, together with the oil and gas industry, which is an integral part of the mineral industry but has achieved its own commercial distinction, it is fair to claim that the mineral industry has played the major role in providing the means for the advancement of the human, quality of life.We do not need to make any great claims on human society in consequence of our statement of these contributions. The facts, for those who are aware of them, speak for themselves. Our more modest interest, as members of our professional association, is to look to the future, while conscious of our heritage as a guide to what more might be done, in that future.We certainly do not claim that this indisputable contribution made to human welfare by the mineral industry gives us some moral position of superiority from which to claim greater support or understanding from the wider community of people.On the other hand we know that as members of the mineral industry we have a responsibility to do what we can to help other people to be aware of, and to understand the significance of, those facts which will only speak for themselves if we take the trouble to make them known. And we have a number of organisations. The Institute itself, The Australian Mining Industry Council, the various State Chambers of Mines, the industrial relations body, The Australian Mines and Metals Association, and others, each of which in its own way endeavours to add strength to the individual efforts which we each should make.We may look at these facts about our mineral industry as simple dry statistics, even with their undoubtedly improving trends, or we can see them, and portray them to others, as expressing something which is much more. We can portray them as expressing the outcomes of our professional determination to strive to do better, whatever it i,s we find ourselves doing in this mineralindustry.We may seek to describe our efforts as being in pursuit of excellence, or by other such high-sounding phrases, but I prefer to describe those efforts as simply our strivings to make everything we do better next time-much as the dedicated golfer tries to do, but with, may I suggest, more evident success achieved in the mineral industry; which is one reason why I don't try to play golf.May I suggest to you that trying to do better, is very simply the true basis of professionalism? We are trained and practised to see the opportunity for improvement-not to be static in a world which we know is changing so rapidly in every aspect around us. We must be dynamic, which means optimistic, about improving the world in which we find ourselves.

Jan 1, 1988

The techniques used in evaluating gold placers and in recovering gold therefrom are briefly reviewed and critically assessed, relative to the estimated and actual recoveries from many operations. The discrepancies between these quantities can be significant and sometimes disturbing. The coefficient of variation for the annual percentage recoveries, relative to the estimates, is in excess of 10 and commonly above 20 . The difficult- ies in evaluating placers are recogni- sed both in the gathering of meaning- ful sample data and in the derivation of estimates. There are deficiencies, perhaps insurmountable at reasonable cost, in the techniques used to derive an estimate and in the gold saving devices usually employed. There is a subconscious trend to use recovery as a check on the estimate. The industry could have extracted more information during the evaluation and working of deposits in order to fully characterise them and in order to quantify metallurgical efficiency. There is a place for other prospecting techniques, particularly geophysical, in placer evaluation and a need for more appropriate and sophisticated

Jan 1, 1976

By McGregor GW

The Utah International group of companies has a wide geographic spread of operations, including a significant interest inAustralia's largest coking coal operation in Queensland, steaming and coking coal mines in USA, a copper mine in Canada, a half interest in an iron ore operation in Brazil, a number of smaller operations, and a significant portfolio of undeveloped properties in South America, South Africa and South East Asia.The opportunity to acquire this group of companies presented an immediate problem to BHP in that it was regarded as too large for BHP to absorb by itself. In addition, there was a concern that such an acquisition would increase BHP's coking coal exposures to unacceptable levels. Despite these dilemmas, BHP was keen to acquire Utah.A plan was therefore developed and agreed to by General Electric (GE) (the then owner of Utah) which would give BHP nine months in which to put together a consortium to share in the ownership of the Queensland coal assets (plus coal assets owned by BHP), and to arrange a project financing for use by BHP and the consortium. BHP would own 100% of the rest of the assets.

Jan 1, 1985

One common public perception of mining is that financially it is an extraordinarily risky business. Another and contrary view, in certain circles, is that price risk and other financial risks can be relatively easily removed or shifted by a number of schemes or devices. In reality, beyond the orebody discovery stage, mining need not be any more risky than most heavy industrial businesses. Nevertheless, as stated by Rappaport, (1986): Risk is a parameter of central importance in establishing the economic value of any asset. The level of risk is determined both by the nature of the firm's operations and by the relative proportions of debt and equity used to finance its investments. These two types of risk are commonly referred to as 'business risk' and 'financial risk' respectively. The term financial risk is used somewhat more loosely herein to recognise the reality that any risk inadequately addressed in the design, construction and operation of a mining project can have significant financial consequences; usually negative. For instance, a specific area of business risk in mining is often called technical risk which definitely has severe financial consequences if not managed correctly. The various risk shifting, hedging and risk management tools available all have their place and range from merely useful to almost indispensable. However, in the long-term, financial risks are maintained at acceptable levels by the application of sound, more fundamental business management principles. There are many with a vested interest in perpetuating a perception that the conceptual foundations of sound management practice are extremely complex. In reality, most management concepts are prosaic, but their application requires incredible discipline and hard work. There is no magic formula or 'silver bullet'. It appears that a company whose activities are restricted to mining can analyse the range of risks specific to mine development and operations more clearly than companies in which mining is just one of many businesses. The almost universal failure of large oil companies in the mining business is probably the best example of lack of any clear comprehension of fundamental business characteristics and risks. Conversely, in regard to risk management, choosing to be in other business as well as mining does nothing to reduce the risks of the mining business. The individual shareholder can probably make such 'diversification of portfolio' decisions better than most management teams. It could be argued that diversification across a number of disparate businesses may actually increase overall corporate risk due to lack of management concentration and focus. These differences between the perceptions of financial risks and the realities in mining need to be further elaborated in relation to some uncompromising business concepts.

Jan 1, 1994

Pyrrhotite is pyrophoric when in a finely divided form. The problems of disposing of large quantities of finely divided pyrrhotite separated out by metallurgical processing from ore are formidable. In the case of an underground mine, a solution to the problem of disposal is to place the pyrrhotite in the stoped out areas and seal from any air supply. Further, the pyrrhotite could be diluted with tailings which would reduce the possibility of combust- ion. Several enquiries to various centres and authorities have shown that the products of the slow oxidation of pyrrhotite with moisture present can cement an inert matrix into a stable fill similar in physical prop- erties to fill stabilised with Portland cement. Stabilised fill can be used to advan tage with a suitable mining method to provide high recovery. The investigation demonstrated that air and 15% w/w water must be present for the fill to harden and that the sizing of the particles is a critical factor in drainage of a hydraul- ically placed fill and subsequent even harden- ing of the fill in a stope. With the materials used in the experiments in which the - 51 micron component of the tailings had been dis- carded, an optimum mix was found to contain 4:1 tailings/slag ratio and an overall pyrr hotite concentration of 8% (all proportion by weight). Approximately 34 days after drain- age to 15% moisture in natural air flow condit- ions, an unconfined compressive strength of 1.862 MPa was attained. A subsequent experi- ment was conducted with a sample of optimum mix in a pipe one metre long in forced air flow conditions. At a superficial velocity of 3.Om per hour the mix required 155 hours to harden to 1.862 MPa after drainage to 15% w/w moisture content. The pressure drop bet- ween the top and bottom of the mix in the pipe remained constant at 9 KPa/metre length. This result suggests that forced air flow conditions will increase the rate of hardening. No dangerous effluents were detected in the course of the experiments which could affect mine equipment or personnel.

Jan 1, 1973

By B N. Morrison

In all metallurgical plants metallurgists require analyses of the various intermediate products, eg flotation feeds, flotation concentrates, tailings, mattes, slags, etc to monitor the efficiency of the plant processes and for plant control purposes. Traditionally these samples have gone to off-site laboratories and there can be some considerable delay before analytical data are received. On-line monitors have to be used for plant control purposes and these are difficult to maintain and can give poor quality data. Recent technological advances in automation in analytical laboratories now allow a far quicker turn-around time for analytical data so they can be of more use to the metallurgist. Automation, which involves the use of robots and fewer people in laboratories, has the added benefit of providing higher quality data as the possibility of human error and bias is minimised. Differences between conventional manual laboratories and automated laboratories are described. Automated analytical laboratories are now becoming the laboratories of choice for mining companies which require large numbers of samples to be analysed on a 24/7 basis on similar sample types using the same sample preparation methods and analytical procedures. Automated laboratories have now been installed in platinum, iron ore, copper and aluminium producing mining companies. A further advantage to metallurgical plants is now the possibility of siting automated analytical laboratories in-plant and designing the plant around the laboratory. Concentrator streams, slags, etc can be sampled by automated samplers, the samples transferred by automation to the in-plant laboratories and all sample preparation and analyses carried out by automated processes. These laboratories require a minimum of staff. Such automated in-plant laboratories have been installed on a platinum mine flotation plant, a platinum mine smelter and steel plants. One is in process of being installed on an iron-ore mine with the sampling being carried out by an automated sampling tower. The procedures followed in planning an automated analytical laboratory for a metallurgical plant are described in detail in the paper. The platinum plant smelter automated system which includes rapid transport of samples by air-tube to the laboratory for the analysis of the samples by XRFS is also described in the paper. It is concluded that automated analytical laboratories can be retro-fitted to most metallurgical plants but they are best suited to greenfield sites.

Jan 1, 2008

ALTHOUGH discovered as long ago as 1817, by Strohmeyer, the use of cadmium did not become in anyway general for nearly a century. Its properties, although well known, did not recommend it to users of metals generally, and it was, on the whole, regarded more in the light of a nuisance to zinc producers than anything else. Its real value was not appreciated until both the United States of America and Germany, who are entirely dependent on outside sources for their supplies of tin, were faced with the unpleasant fact that their tin stocks were being rapidly depleted, with practically no prospect of having them replenished. This resulted in serious efforts being made in the UnIted States of America to conserve what tin was available, and, as a consequence, several metals were tried in the hope that they would prove satisfactory substitutes for tin. Among these was cadmium, and it was found that cadmium could replace tin in a manner sufficiently satisfactory to permit of its use in many directions where tin had been used before.It is on this ability of cadmium to replace tin that its use became in any way general at first; but since then new avenues of development have been opened up in which its physical and chemical properties are proving their value. It is highly probable that its use will extend very considerably as time goes on. OCCURRENCE OF CADMIUM.There are several cadmium minerals known, but none of them occur in profitable quantities as ores. The cadmium of commerce is derived almost entirely from zinc minerals and ores in which it is almost invariably present in proportions which are usually very small. Cadmium behaves metallurgically almost the same as zinc, and hence constitutes a fraction of 1% of almost all spelter.

Jan 1, 1923

By S Brochot

In cases where coarse gold is present in a deposit, it is usual to use the screen fire assay (SFA) method to analyse the samples. There is no doubt that this method is more accurate than the standard fire assay (FA) and reduces the risk to have a systematic bias. Nevertheless, the difference between the analytical errors of both methods can be glossed over when the overall sampling error is added to obtain the measurement error. In that case, the advantage of the SFA cannot justify its higher cost.The current paper attempts to address this question in the case of a gold ore deposit with visible coarse gold in various sampling situations (drill core sampling in exploration, blasthole or chip sampling in mining exploitation). The overall measurement error is estimated taking into account the analytical error and all the sampling error components following the Pierre GyÆs theory of sampling.Firstly, only the last sampling stage is considered when the pulverised sample is processed either to obtain one analysis sample for a FA or to be screened and subsampled for a SFA. The calculated measurement error clearly shows the advantage of the SFA specifically in presence of coarse gold. Secondly, the half core sampling is studied to explain the observed discrepancies when controlling the second half core. Finally, the blasthole sampling is treated using in situ heterogeneity models to show that the relative advantage of the SFA is hidden by the large overall sampling error.In conclusion, the choice of the assaying method is discussed at the light of the overall measurement error and in accordance to the analysis objective.CITATION:Brochot, S, 2012. Standard fire assay or screen fire assay? Application of the overall measurement error approach to choose the most appropriate method, in Proceedings Sampling 2012 , pp 135-142 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 21, 2012