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By Alfred Osborne

Progressive cavity type pumps are widely used by commercial explosive manufacturers for pumping water gel, emulsion and emulsion / ANFO blend explosives. Tests by explosives companies and investigations into incidents have shown that this type of pump can develop dangerously high temperatures when operated deadheaded or dry. [i.e. with no flow of product through the pump.] In some tests and incidents, explosion or detonation of the explosive (or residual explosive) in the pump has resulted.

Jan 1, 2002

Fluid inclusions and sulfur isotopic compositions were studied in a possible extension of the Toyoha polymetallic vein deposit. The objective of this work was to gain a better understanding of the ore depositional conditions, sources of ore constituents, and distribution of mineralizing fluid in the region. Fluid inclusions in sphalerite and quartz show that most homogenization temperatures range between 190¦ and 290¦C. Most salinities range from 0.0 to 3.4 wt per cent NaCl equiv. Sulfur isotopic compositions of ore minerals (pyrite, sphalerite and galena), determined by a conventional technique, range between 1.3 and 7.7 per mil. The mineralizing fluids were characterized by relatively low and various temperatures and low to moderate salinities compared to those at the southeast region of the main ore bodies (Izumo and Shinano veins) where rare elements such as tin, tungsten and indium occurred. Obtained temperatures and salinities were attributed to the mixing of hydrothermal fluids with groundwater. Sulfur isotopic data suggest sulfide sulfur was of magmatic origin. Isotopic temperatures, estimated from the isotopic fractionation factor between sphalerite and coexisting galena, are between 195¦ and 322¦C. The temperatures are only consistent with fluid inclusion homogenization temperatures in sphalerite or coexisting quartz when sphalerite was a honey-yellow coarse crystal lacking conspicuous colored growth bands. This suggests the detailed classification of mineral pairs growth textures will be necessary for precise in situ measurements to obtain reasonable eothermometric results.

Jan 1, 2002

Thank you for the opportunity to speak at this important conference attended by aspiring mining professionals, some of whom will become the leaders of the mineral resources industry that forms the solid foundation of AustraliaÆs past and that will fuel the exciting growth of AustraliaÆs future.I want to briefly touch on the history of our business, then look at the opportunities that exist in the contract mining industry and finally comment on what the educators need to consider in their curriculum to meet the needs of our business. Byrnecut started out as an idea in early-1987 developed by a group of four mining people. At the time the industry was on the high end of a mining boom, the era of the Bonds, Connels, Skases and so on. Riding on this wave of euphoria we borrowed $600 000 from the National Australia Bank and, without having enough knowledge to lose sleep over the potential risks, started business in mid-1987. The euphoria quickly evaporated with the 1987 October stock market crash. The bank pulled our overdraft, equipment finance rates increased to over 20 per cent per annum and my house was mortgagedseveral times over. The business learning curve was extreme for a young mining engineer who had developed his trade in the relatively sheltered environment of a large public mining house, namely WMC. We were somewhat bitter that the banks had done a runner. We were a private company, backing the business with personal assets with our shoulders to the wheel, whilst the Bonds of the world had theirnoses in the trough ripping off mum and dad shareholders. All of this had a sobering effect, namely keep your feet on the ground, stick to the knitting, work hard and worship cash flow. Since that stressful but adrenaline pumping beginning the company now employs over 600 people and is now working for major mining houses at over a dozen locations in Australia, east Africa and WesternEurope and the National bank is again our banker. On this basis I consider myself qualified for the subject of this speech.

Jan 1, 2002

By K. Burke, G. Zhan, A. Mayer

A cover with capi1lary barrier effects (CCBE) is being constructed an the AA leach pad at the Barrick Goldstrike mine near Carlin, Nevada. The purpose of the cover is to eliminate/minimize infiltration of meteoric waters into the leach pad. Laboratory and numerical analyses indicate that Carlin Formation siltstone (TCS), a locally available material, has the necessary hydrologic characteristics when placed on the leach pad to act as a CCBE. A pilot study was conducted on a mall-scale test cover placed on the AA leach pad to examine the cover performance under irrigated conditions. The preliminary test results demonstrate that the designed cover is capable of preventing meteoric water infiltration.

Jan 1, 2002

By M Dorricott

This paper describes the design, construction and performance of sill pillars using cemented development mullock at the Crusader Gold Mine. The orebody is some 35 m - 60 m in length, 5 m - 8 m wide, dipping at 60¦ - 85¦ and plunging at about 40¦ to the north. It is accessed via a footwall decline. The ore occurs at the contact between basalt and ultramafic. This contact is characterised by shearing and alteration; and is prone to unraveling failure. The cut and fill mining method at Crusader extracts 25 m high ore blocks in four flat back lifts and one 8 m thick crown pillar. To enable full recovery of these high-grade crown pillars with minimal dilution, a 5 m thick sill pillar is constructed using cemented rock fill (CRF), after mining of the bottom two lifts in each block. Uncemented development mullock is used as rock fill (RF) for subsequent lifts. Development mullock and cement/water slurry is mixed underground to produce CRF. The fill is transported to the stope in LHDs and dumped on the floor. The sill pillar is advanced progressively, with compaction provided by the loader driving over the previously placed fill. Old jumbo rods are installed as shear pins along the flat dipping hangingwall to reduce the risk of rotational failure of the pillar. A fan of cable bolts is installed into the hangingwall to prevent unraveling failure in the sheared ground. Buffer blasting is used to minimise damage to the CRF sill pillar when the crown pillar below is extracted. At the time of writing, extraction of the crown pillar underneath the CRF has taken place at the 930 stope. The crown pillar was extracted successfully with dilution from the backfill and hangingwall minimised and 98 per cent of the gold recovered. This compares with pillars that were mined beneath uncemented backfill where only 70 per cent of the gold was recovered and where there was significant dilution from the backfill and from hangingwall failures. Where no CRF was placed, there were also numerous production delays caused by large rocks from the hangingwall blocking the stope brow.

Jan 1, 2002

By Jasper Kwong

The recycling of MgO-C refractories as a slag conditioner in EAF (electrical arc furnace) foaming slags have been evaluated by the Albany Research Center. The amount of MgO in the slags is critical for the foaming quality. Good foaming slags provide the benefits of high energy efficiency and low refractory consumption and require saturation with MgO. A computer model predicting the chemistry of MgO saturated foaming slags was designed to predict suitable amounts of MgO additives from MgO-C spent refractories. This model can also help to reduce the amount of slags and to improve the economics of producing steel. The implementation of this recycling program is underway at steel plants and the experience of recycling spent refractories will be discussed.

Jan 1, 2002

The BHP Billiton Cannington Mine uses paste as the principal method of backfill. The paste consists of mine tailings and cement. The pastefill process at Cannington includes a surface plant where the thickened total tailings stream is filtered using two vacuum disc filters operating in parallel. The filter cake is mixed with Portland cement in a spiral mixer to produce a paste at a specified yield stress and cement content. The initial system design only required paste to be delivered under gravity. In July 2001, Cannington Mine expanded to 1.8 million tonnes per annum. In order to achieve this, production commenced on five new levels underground, 350 metres horizontally from the paste plant. Due to the high viscosity of paste, this distance was too far to transport by gravity. Traditionally, paste has been transported only short distances (50 m) using positive displacement pumps, with very limited success. At Cannington, a conveyor was installed which was designed to achieve zero spillage into the environment. This paper discusses the innovative design strategies used to attain zero harm on the environment whilst conveying a material, which is difficult to transport.

Jan 1, 2002

Although the mining of metals was well established by the time of the Roman Empire mining skills did not really advance greatly for many centuries. Miners did not have the scientific knowledge to distinguish minerals, to process them, and to obtain the best recovery. Each mine essentially developed its own methods in isolation, most of them dangerous. However, with the beginning of the industrial revolution in the early 18th century there was a rapid increase in mining activity in Central and Western Europe and an accompanying need to educate professionals in the developing fields of science and technology. There was also a need for specialised schools (for example, Schools of Mines) to accomplish this since the universities of the time, formed as early as the first half of the 12th century, were cloistered institutions, focused on the study of classics, theology and law. The earliest attempts at organised technical education were made in 1702 with the establishment of a School of Mines in Frieberg, Germany (Table 1) to service rich copper mines, and in 1747 with the establishment of a School of Mines in Paris. By this time, the industrial revolution was well under way and other Schools rapidly followed, at Clausthal in the Ruhr region of Germany in 1775; in 1777 at Almanden to service the mercury mines of Spain (later transferred to Madrid); in 1780 at St Petersburg, Russia and at Falun, Sweden in 1819. The academic staff for these new institutions were often trained in the original School at Frieberg.

Jan 1, 2002

The beneficiation of heavy metal oxides, such as iron ore, is usually performed with heavy medium separation in cyclones, static baths and lately with Larcodems. Atomized ferrosilicon is most suitable as a heavy medium at densities above 3600 kg/m3 whereas a mixture of milled and atomized ferrosilicon is suitable at densities below 3600 kg/m3. When operating a beneficiation plant at densities higher than 3600 kg/m3 the quality of the ferrosilicon particles is an important factor that influences the control of the beneficiation process. Therefore, it is important to know how the rheology would be affected by the ferrosilicon quality as it also influences the control of the process at these elevated densities.

Jan 1, 2002

By J. R. Kunkel, V. Lishnevsky

At mine sites, the operational and required storage volumes of solution and water storage ponds and reservoirs are usually calculated based upon a water-balance approach. Many climatological variables including precipitation, air temperature, solar radiation, pan evaporation and relative humidity along with operating parameters, are used in the water-balance model. The water-balance model often seeks to find a “critical period” of wet or dry climatological sequences which result in a “maximum” pond storage volume or water demand. The problem with this approach is that the designer usually does not know when the project will come on line in relation to the historical record. To avoid this pitfall, we use a more robust approach. In the more robust method, the water-balance calculations begin in each year of the historic climatological record. This method results in the same number of water-balance runs (or realizations) as the number of years of climatological record. Results of this type of analysis guarantee that the critical period or maximum required pond volume will be found if it is assumed that the historical climatological record repeats itself or if a synthetic time series is used. In addition, this method permits calculation of the likelihood (probability) that a given pond volume will be equaled or exceeded in any given month of the operational life of the facility. In this paper, the results of the sizing of a heap leach pad solution pond are presented along with the probabilities of a given solution pond size being equaled or exceeded based on the robust water-balance approach.

Jan 1, 2002

By Jacob Masliyah, Zhiang Zhou, Tshitende Kasongo, Jianjun Liu, Zhenghe Xu, Jeawon Choung

"Slime coating is a recognized challenge in fine particle flotation, not only in decreasing recovery, but also in reducing the selectivity and hence froth quality. In this presentation, a novel method based on electrophoretic mobility distribution measurement to study slime coatings is described. By measuring electrophoretic mobility distribution of individual minerals and their mixtures, the interactions between these minerals can be evaluated.For illustrative purposes, a model system of fine coals, or oil sands with two different types of fine clays was studied. Flotation tests showed a significant decrease in coal (bitumen) flotation recovery with montmorillonite but not with kaolinite clay addition. When electrophoretic mobility distribution of a fine coal/montmorillonite clay mixture was measured, a single modal zeta potential distribution was obtained, in contrast to a bimodal distribution for fine coalkaolinite clay mixture. This finding suggests a stronger adhesion of montmorillonite than kaolinite clays on fine coal surfaces. In the case of bitumen, the bimodal zeta potential distribution was measured for the mixture of bitumen emulsion and kaolinite or montmorillonite, indicating a weak attraction of the clays by bitumen. In the presence of calcium, however, a single modal zeta potential distribution was obtained in the mixture of bitumen emulsion with montmorillonite but not kaolinite clays. These findings are in excellent agreement with bitumen flotation results, demonstrating that the electrophoretic distribution measurement is a powerful tool to study slime coating phenomenon in a complex fine particle flotation system."

Jan 1, 2002

By J. A. Organiscak

Data on dust-control practices, mining conditions and occupational exposures were gathered for approximately 80 underground continuous mining units. Despite silica contents on dust samples in excess of 5%, nearly forty units successfully maintained silica concentrations at or below 100 µg/m3 on a majority of occupational dust samples, while the remainder had difficulty maintaining this level. These two sample sets were termed Group A operations and Group B operations, respectively. This data was compared to identify causes of high occupational silica dust exposures. Analyses of dust-control parameters and geologies revealed only minor differences between these two groups. However, subsequent comparisons of face ventilation design showed considerable differences in silica exposure and silica content between Group A and Group B at the continuous mining machine and roof bolter operator occupations. These differences were minimal when using exhaust curtain ventilation with a dust scrubber. This face ventilation system can benefit operations having difficulty controlling silica dust exposure and silica dust content. The collected data also showed that occupational samples from Group B operations possessed generally higher silica exposures and silica content than similar samples from Group A. The single head roof bolter (helper) possessed among the highest silica exposures and silica contents in both groups.

Jan 1, 2002

By Nilce Alves Santos, Vânia Lúcia de Lima Andrade, Keila Lane Carvalho Gonçalves, Harold Wyslouzi1

"When confronted with the difficult decisions on advancing an exploration project to the feasibility and construction stages, it is important to know how various regions of the ore body will react in the milling and concentration processes. While bench scale test work is common and inexpensive, the results and information provided are somewhat limited due to the difficulty in accurately predicting the effects of recirculating middling streams or gradual changes in solution chemistry.Conventional Pilot Plants, processing 100 to 1,000 kg/hour of sample ore, provide the detailed engineering data required to develop a final process flowsheet and to size the equipment. They are, however, expensive to set-up and operate, and are really only viable for major projects that are well advancedIn the latter part of 1999, the Mineral Development Center at CVRD (MDC) purchased a new piece of mineral processing equipment which can run continuous flotation tests using drill core samples. To evaluate its performance, and to compare it with conventional testing methods, various types of flotation tests were carried out using two different types of copper ore. The limitations and advantages of open circuit and locked cycle bench tests, as well as the Mini Pilot Plant and the Conventional Pilot Plant were evaluated.Open circuit tests carried out at the bench scale only provide basic information. More complete and trustworthy information is obtained, in terms of the recirculation of flows and reaching a permanent and stable flotation regime, as the dynamics and complexity of the tests increases. The data obtained showed that the MPP’s metallurgical performance was equivalent to that of a conventional pilot plant."

Jan 1, 2002

While specific definitions of the main categories of mineral reserves and mineral resources are becoming well established through the efforts of the Australasian Joint Ore Reserves Committee (JORC) and the Combined Reserves International Reporting Standards Committee (CRIRSCO), there has been perhaps less attention paid to the standardisation of language used in the definition and reporting of Mineral Exploration Results and a clear understanding of the transition to Inferred Mineral Resources. This is an area of significant importance to small and medium sized enterprises in the mineral exploration sector as it represents in many cases the only tangible information by which the reader or potential investor can evaluate the future potential of such enterprises. By its very nature information in the Mineral Exploration Results category is incomplete, and frequently complex, and it is open to a broad range of interpretation by readers of various competency levels and disciplines. Many will have a short-term speculative view rather than a long-term perspective, with others out deliberately to misrepresent the information, and as such it can have an enormous impact on investment decisions if the risks associated with this information being reported are not fully understood. Authors of reports on Mineral Exploration Results, who may be Competent Persons or company directors, have to put themselves in the shoes of the reader of the report, second-guessing if you like what the reader will understand by a report, which in many cases will be of a highly technical nature. This raises reporting dilemmas and questions that require to be understood and addressed. Looking at reports on Mineral Exploration Results from the other side, readers have a degree of responsibility as well, particularly if they engage in an advisory or communications role. The tendency of commentators, journalists, analysts, and bulletin board posters to over-exaggerate the significance of a particular exploration result is all too familiar. Questions arise here as well about whether there should be more regulatory supervision and control exercised over those who use this information, all of whom greatly influence investment decisions, and many of whom have no idea there is a Reporting Code, far less an understanding of it. Examples are given and questions raised to illustrate the dilemmas surrounding the reporting of Mineral Exploration Results. In order to retain credibility with markets it is incumbent on companies to be transparent, not to be selective and to report all material information. On the other hand, information has to be taken and read in its proper context in order to avoid fuelling dramatic and unjustified company share price escalation. Timing of course is another factor that can affect the market price of shares, which may be beyond the control of those making the reports. Emotive and imprecise language, however, when reporting Mineral Exploration Results, coupled by speculation, can trigger damaging short runs on shares and destroy credibility where formerly there was long-term promise. The paper will review how Mineral Exploration Results are dealt with in various jurisdictions, and conclude that there has to be a balance between prescription and the tempering of undue optimism on the one hand, and the entrepreneurial spirit, which the industry needs, on the other.

Jan 1, 2002

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

Jan 1, 2002

By K. W. Grubaugh

Indigenous people are nearly always affected when projects enter their territory. Crop and other asset compensation can help or undermine a project’s progress depending on the approach. When compensation is handled poorly, a technically viable project can get indefinitely entangled by local unrest. Stake holders associated with compensation issues include; the state, the indigenous people, non-governmental organizations, and the developer. Appreciation for the unique perspective of indigenous peoples and the influences affecting them can avert problems and prevent delays. A review of the compensation issues encountered in Ghana during its recent gold boom can assist in avoiding problems associated with handling poor and uneducated people.

Jan 1, 2002

By S. Surapunt, C. M. Nyamai, K. Itagaki

"The use of liquid copper as a medium for zinc extraction has been used in the Warner Process as a method of processing zinc-lead sulphide ore. The recovery of zinc metal is based on the reaction:ZnS(s) + 2Cu(l) = Zn(g) + Cu2S(l)In this method, thermodynamic and phase equilibria investigations of the Cu2S-FeS-ZnS and Cu2S-PbS-ZnS systems are of importance and form the basis for the liquid sulphide phase which appears as a product and is used as a solvent in the Warner Process. Phase relations in the Cu2S-FeS-ZnS and Cu2S-PbS-ZnS ternary systems were determined experimentally at 1473°K to provide a fundamental basis for the new zinc smelting process. The results show that the solid solubility of ZnS in the two systems is very small (2 wt% to 3 wt% ZnS in FeS, 4 wt% ZnS in Cu2S for the Cu2S-FeS-ZnS system; less than 0.5 wt% ZnS in both PbS and Cu2S for the Cu2S-PbS-ZnS system). The Raoultian Activity Coefficient of ZnS in the liquid mixtures and the vapour pressure of zinc over the matte in both systems is relatively large (?° = 7.7 – 15.8, Pzn(atm) = 0.088 – 1.026 for the Cu2S-FeS-ZnS system; ?° = 8.9 – 12.9, PZn(atm) = 0.075 – 0.214 for the Cu2S-PbS-ZnS system). On the FeS-ZnS join, the only phases detected are FeS and iron-rich sphalerite (Zn, Fe)S. The binary join mixture occurs at about 92 wt% FeS-8 wt% ZnS at 1473°K. Electron microprobe examination of the quenched samples indicate about 47 wt% to 48 wt% FeS in sphalerite and about 2 wt% to 3 wt% ZnS in the iron sulphide phase. On the Cu2S-ZnS join, microprobe analysis reveals that the maximum solubility is 4 wt% Zn in liquid Cu2S and 3.6 wt% Cu in solid ZnS. In the Cu2S-PbS-ZnS ternary system, microprobe analysis of the quenched samples indicate on average, 5 wt% ZnS in the liquid phase region. The only phases detected on the PbS- ZnS join are ZnS and PbS. The eutectic phase contains, on average, 13 wt% ZnS. The phase relationships, very low solid solubilities of zinc sulphide in the liquid mixtures of both Cu2S-FeS-ZnS and Cu2S-PbS-ZnS systems, coupled with the high Raoultian Activity Coefficient of ZnS as well as the high vapour pressure of zinc over matte all favour the partitioning of zinc metal into the vapour phase. This new process is cost effective and bypassesthe expensive and tedious conventionaltechnique of zinc production involving oxidationof the sulphide ore by roasting followed bya reduction process to extract the zinc. Theresults indicate that a new zinc smelting technologyusing the Warner Process would bemore efficient and preferable over the traditionalmethods of zinc extraction."

Jan 1, 2002

By L. Gertsch, R. Gertsch

Mechanical mining is steadily gaining in usage in the mining industry. A variety of machines are now being used, including tunnel boring machines, roadheaders, continuous miners, surface miners and augers. These machines have advantages compared to drill-and-blast mining methods, including increased safety, lower cost, uniform muck size and accurately sized openings. A century of experience with mechanical methods has paid dividends to the coal industry. Current trends guarantee eventual development of true general-purpose hard-rock mechanical mining machines. When several significant challenges have been met, mechanical miners will become integrated mining systems and will determine the design of mines.

Jan 1, 2002

By T Davis

Cameco Corporation operates the high-grade 140 tpd fly-in/fly-out underground McArthur River Uranium Mine in Northern Saskatchewan in a joint venture with Cogema Resources Inc. Reserve grade is in excess of 20 per cent U3O8 with current mining grade averaging 16 per cent U3O8. Due to the high radiation potential of the ore, the non-entry mining method of raiseboring was chosen to minimise worker radiation exposure potential. The raisebore and extraction horizons are located in waste rock with the orebody located between horizons. Ore produced by raiseboring is delivered by LHD to an underground SAG mill and is then hydraulically hoisted to surface receiving facilities after underground thickening to 50 per cent solids by weight. Concrete backfilling is utilised. The orebodies at McArthur River are adjacent to water bearing sandstone. Ground freezing is therefore employed to isolate the ore from this water bearing ground. Calcium chloride brine at -35¦C is circulated through a series of cased boreholes to establish freeze walls up to 25 metres in thickness. At 18 000 000 lb of low cost U3O8 production per annum, McArthur River ranks as the worldsÆ largest uranium mine. Over 50 per cent of the workforce resides in this sparsely populated area of Canada with approximately 40 per cent being of aboriginal ancestry. Site operations must cater for winter temperatures as low as -50¦C.

Jan 1, 2002

By M. Heger

February 2, 1999 marks a milestone in earth-moving technology at the San Miguel Lignite Mine. It was on that date that The North American Coal Corporation (NAC) took delivery of three Leica Dozer 2000 GPS grade control systems for use on its bulldozers. The primary reason for the purchase of these grade control systems was to prove that GPS technology could safely and economically be utilized on heavy equipment to assist operators in defining grades. If these properties were successfully demonstrated, the ultimate vision of the project was to expand the system to a point were GPS would become the primary means of providing grade control information to the mine’s heavy equipment operators. Twenty nine months and more than $500,000 later this vision was realized when the final bulldozer operating at the San Miguel Lignite Mine was equipped with Dozer 2000. Presently North American Coal has a total of nine Dozer 2000 GPS grade control systems at San Miguel providing cut and fill information to operators 24 hours a day. These grade control systems have allowed the San Miguel operation to increase safety, reduce costs, improve operator attitude, and better ensure environmental compliance. This article discusses both the nature of these benefits and some of the issues that had to be dealt with along the way.

Jan 1, 2002