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This paper describes the behaviour, under creep conditions, of a cast lead creep specimen consisting of five crystals, the boundaries of these crystals being substantially at right angles to the direction' of tension, i.e., across the long axis of the specimen. This particular specimen was obtained in an attempt to produce a single crystal in the manner described in the appendix of a previous paper (1).Thus, the specimen was of the same shape and size, was composed of the same purity lead and received the same preliminary treatment as the single crystal test-pieces.The object of the experiment was mainly to observe the effect of the crystal boundaries on both the deformation of the test piece and the process of recrystallisation and to compare the creep rate of the test-piece with that of a specimen consisting of one crystal only.EXPERIMENTAL METHODThe specimen had an effective test length of 10 cms. and a cross $ection of 0·5 in. x 0·25 in. In Fig. 1 is given a sketch of the specimen to scale showing the positions of the crystal boundaries on all four surfaces. Except for those of crystal No. 4, which was confined to approximately one-half the cross section of the specimen, the boundaries of each crystal traversed the four faces.The specimen was mounted in exactly the same manner as the single crystal specimens. During the creep test, it...

Jan 1, 1941

By Tom Dettweiler, Robina Sharpe, Wright. Michael

The International Seabed Authority and a number of countries have or are in the process of developing environmental impact assessment guidelines and legislation for seafloor mineral development. The formal decision to grant a project an environmental permit is based on an environmental and social impact assessment (ESIA), culminating in an environmental impact statement (EIS). The EIS needs to be supported by sufficient data upon which an assessment of impacts can be made and mitigation measures developed. Given the remote locations of many seafloor prospects, collection of sufficient environmental data to inform an EIS is often a difficult, expensive and lengthy process.

Sep 1, 2014

By Stanley W. Ivosevic

The South-Central Osa Peninsula produced around 30,000 kg (100,000 troy oz) of gold since prehistoric times. Gold freed by erosion from quartz lodes in the Mesozoic Nicoya ophiolite complex was reconcentrated through three generations of Quaternary sedimentary deposits. Resultant gold placers grade upward from 1 g/m3 (0.03 troy oz/m3) and are of moderate size.

Jan 1, 1980

By B. Salt, R. Sullivan, E. Roos, M. de Vries, K. McKenna, L. R. Nelson, M. J. N. Uys, P. Jacobs, E. Munnik, P. Lewarne

A review is presented of the furnace cooling system design and operating developments since the initial furnace start up in January 2001 of the Chambishi DC-arc furnace to produce ferrocobalt alloy. The furnace operating conditions present a number of challenges to the furnace designers and operators in particular to provide a sustainable lining that can withstand the highly corrosive siliceous slag (roughly 50% SiO2). This is exacerbated by the dual requirement to operate this slag in a relatively highly superheated state (?T ? 400°C when tapped at 1550°C) to ensure that the ferroalloy can be tapped (estimated 1370°C alloy liquidus temperature) prior to atomisation. The core design challenge occurs at the alloy-slag interface, where a single refractory type cannot simultaneously meet the dual requirement of both adequate alloy and slag corrosion compatibility. Progression by the fourth furnace campaign to involve a retrofit of the bath sidewall to Hatch high-intensity, water-cooled, copper Waffle coolers and tapblocks is described. This involves operation of the entire slag bath, the slag-alloy interface and a portion of the alloy within a more chemically compatible refractory/slag (and possibly at times even an alloy) freeze-lining. Due to the high furnace power density employed (up to 500 kW/m2 hearth area) coupled with the large slag superheat needed, the resulting imposed peak bath sidewall heat fluxes are substantial, especially in the alloy (typically averaging 170 kW/m2), and on occasion have exceeded 1000 kW/m2. The performance of the Hatch Copper Waffle coolers under such aggressive process pyrometallurgical conditions is described. Aspects of the design and especially operating strategies to effect sustained production at up to 38 MW power input are also discussed.

Jan 1, 2004

The integration of mining and mineral processing technologies into new advanced mining systems is considered to offer several benefits, including selective mining, reduction in waste, increased productivity, flexibility, and improved resource utilization. This paper focuses on underground hardrock mining and the integration of pre-concentration technologies into future mining systems as representing realistic, shorter-term integration options. Control of fragmentation to optimize grinding, pre-concentration of ores, in situ leaching, and modular mining/mineral processing systems are possible with existing technology. Current research is directed toward development of integrated underground systems that minimize surface activity and minimize or eliminate surface waste disposal. Results from a simulation model of an integrated underground pre-concentration system are presented.

Jan 1, 2002

By Ron Webber

With the difficult economic challenges currently facing the steel industry, it is essential to perform a complete analysis when determining which rolls to purchase. A properly designed “Total Cost of Ownership” model can result in significant savings. This paper will review the costs associated with rolls in both Hot Strip and Cold Strip Mills. The multitude of factors that must be considered in performing a complete analysis for the roll purchasing process will be discussed. Models for both Hot Strip and Cold Mills will be presented. Examples where traditional analysis can lead to expensive, incorrect decisions will be presented.

Oct 30, 2017

By L. G. Marshall

The geology, mining, beneficiating, types of products, and costs in terms of percent of total costs and of labor, power, and supplies of two crushed-limestone operations in Madison County, Iowa, are described in this paper. The operations are basically similar, differing in refinements in mining, product types, and markets. The operations are comparable as to personnel and as to weighted costs in terms of percent of total costs and in terms of man-hours, power, and sup-plies. The waste-to-stone stripping ratio is 1 to 0.8 at both operations, the powder factor is 0.29 pound of explosives per ton of stone, and daily production is 95 tons per man-shift. Both companies use crawler-mounted diesel shovels for loading, truck transportation, wagon drills, and dry screening.

Jan 1, 1963

By Michael Young, Peter Allum, Mingwei Gao

"Tough economical conditions and high grade but fine-grained ore processing have forced the mining industry to look for more efficient processes. Isa Mill Technology for ultra-fine and fine grinding is one such process employed at several mining operations in Australia including Mount Isa Mines Limited in Australia. Mount Isa Mines is a business unit of MIM Holdings Limited. MIM is an Australian-based international mining and mineral processing company with around 8000 employees worldwide. Major products include copper, gold, zinc-lead-silver, coal and technology sales.The Isa Mill is a horizontal stirred mill with sizes up to 3 m3 chamber net volume and 1 120 kW installed motor. It was jointly invented by Mount Isa Mines of Australia and Netzsch Feinmahltecknik GmbH of Germany for ultra-fine and fine grinding duties in the minerals industry. Isa Mill operations started in 1994 at the Mount Isa Mines Leadzinc Concentrator and then at MIM’s McArthur River Mine in 1995. These Isa Mills have been used to liberate sphalerite and galena at Mount Isa and silica at McArthur River by grinding to less than 7 micron.This paper discusses the Isa Mill Technology and reports on the metallurgical performance of the Isa Mills at Mount Isa Mines, including work done over the last 9 years to improve mill design, process efficiency and maintenance, which has resulted in the current state-of-the-art Isa Mill Technology.INTRODUCTIONThe current leadzinc deposits at Mount Isa Mines (George Fisher, Hilton and Isa) have an average grade of 10.5% zinc, 7.2% lead and 165g/t silver. Fine grinding, in particular in the zinc retreatment circuit requiring a milled product P80 of 7 micron, is essential to treat the ores from the Mount Isa Mines deposits. Every one micron size reduction in the zinc retreatment circuit below a P80 of 10 micron improves the overall plant zinc recovery by 1%, resulting in an increase in revenue of about 1 million dollars per annum."

Jan 1, 2002

By S. Dessureault

The relatively recent explosion of available data in all business sectors has induced a common expression of “drowning in data, starving for information.” The mining sector is affected by the information age through equipment-based sensors, process monitoring, and traditional enterprise data sources. Information technologists have developed techniques such as data mining that apply new and old statistical algorithms to large datasets. Mine planners and managers can apply these tools for improved planning and control, thereby increasing the use of the highly underutilized information system infrastructure in most modern mines. This paper describes the use of data mining and its enabling technology, data warehousing, in the development of an energy consumption model for large surface mines using real historical data.

Jan 1, 2007

By Ken Musgrave

"A program is described that helps managers and supervisors control maintenance more effectively. Work- order generation, preventive maintenance, repair parts inventory, planning and scheduling, reporting, analyzing costs, printing purchase orders and other functions are covered. Flexibility often permits integration with other programs such as payroll, cost accounting and materials management.The Role of MaintenanceMaintenance provides a service to allow the rest of the operation to do its job effectively. Its success should not be measured by maintenance cost alone, but also by its effectiveness in reducing downtime and maximizing production. It can make sense to spend more maintenance dollars if this results in an even greater contribution from increased production.The Cost of MaintenanceIn mining companies, maintenance costs can be as much as half of operating costs. Maintenance has generally not been given the management attention that an expenditure of this magnitude deserves."

Jan 1, 1986

The effect of long term exposure of full size bolts to corrosive environments is presented. A special test rig was used to test four bolts under different loading conditions. Four, X-grade identical profile bolts, each of 21.7 mm core diameters (23.7 mm full diameter) were subjected to prolonged corrosion testing using acid sulphate water. The pH value of the circulated water varied between 3.4 and 4.3. The corrosion exposure test period lasted three and half years. Two bolts were axially loaded to 10 and 20 tonnes force respectively, the third bolt was subjected to a 360 Nm torsion load and the fourth bolt was left unstressed to act as a reference bolt. After the test period ended, the bolts were stripped of their corroded coatings and weighted for weight loss. The diameter of each bolt was subsequently measured, and the loaded bolt samples were first tested non-destructively for tensile cracks and then tested for tensile failure. No cracks were found on post corrosion bolts tested non-destructively. The failure strength reduction on all four post-corroded bolts was significant, varying between 21% and 39%. The onset of corrosion was not confined to the targeted mid-section length of the bolt, however, the severest corrosion occurred at the anchored ends of the bolts.

Aug 1, 2013

By H. E. Urtubia

"BHP-Billiton’s Minera Escondida Limitada, in Chile, is one of the world’s largest copper producers. It treats a combined 10,500 tph of copper ore through its two concentrators: Los Colorados and Laguna Seca. The performance of the rougher circuit at each concentrator was measured and analysed using the JKTech flotation optimisation methodology. This involved developing a flotation model for each concentrator based on cell operating parameters (for example bubble surface area flux and froth recovery) and feed ore floatability characteristics. The rougher circuit performance was evaluated in terms of traditional measures, such as grade and recovery. The operation was also analysed using the measured cell operating parameters and ore floatability and the effect of these with regard to performance (grade / recovery) was assessed.This paper presents a comparison of the rougher circuit at each concentrator in terms of these parameters. The main differences in rougher circuit performance between the two plants were attributed to differences in feed ore floatability characteristics and froth recovery. The comparison highlighted opportunities where performance improvements could be made. The study also showed the usefulness of separating the flotation process into easily measurable subprocesses to further identify the different mechanisms occurring in each rougher circuit. Traditional measures like grade and recovery are useful for monitoring flotation operation but this data lacks the depth to determine the root cause behind operational issues. Determining the operating parameters and ore floatability provides the operating plant metallurgist better tools to assess and manage these issues."

Jan 1, 2006

By James A. Barr

Prospecting methods used in Tennessee have gradually improved with the years, as required by depletion of the easily accessible and shallow deposits and the universal trend toward mechanization, and as necessitated by exploring deeper beds, often occurring under limestone and flinty overburden. In the early days it was a very simple matter to dig pits by hand, using a plentiful supply of local farm labor to expose relatively shallow deposits of "brown rock" under shallow clayey overburden that would stand up without timbering. Visual inspection of the exposed phosphate and expert judgment of the "grade" analysis, aided by a "biting" test to reveal presence of unwanted silica, furnished most of the information required. All this might be helped by a few samples sent to the local chemist† who supplemented his income by judicious trading or tanning a few bear skins. The extra curricula activities did not affect the accuracy of the analysis which hold up even under present day standards. Some shot and core drilling was done in Hickman County, mostly for the limestone-like blue Phosphate deposits. The next step was the use of a 4-in. posthole auger, hand operated as described by Guenther, followed by a completely mechanized rig, as described by Pickard. Both these methods are practically adapted to the prospecting of the relatively soft brown rock deposits at moderate depths of clay overburden. For prospecting in areas of deeper overburden, such as are often found in Hickman County, up to 150 or even 200-ft depths, a modified core-drilling method is described by Guenther. Johnston describes a special diamond-drilling technique, developed by TVA, to penetrate flint horizons, which was adopted by the International Minerals in chemical corporation to prospect in Hickman County where deposits had previously been prospected at considerable expense and with difficulty, by small, temporary, hand-dug shafts.

Jan 1, 1948

By James A. Barr

Prospecting methods used in Tennessee have gradually improved with the years, as required by depletion of the easily accessible and shallow deposits and the universal trend toward mechanization, and as necessitated by exploring deeper beds, often occurring under limestone and flinty overburden. In the early days it was a very simple matter to dig pits by hand, using a plentiful supply of local farm labor to expose relatively shallow deposits of "brown rock" under shallow clayey overburden that would stand up without timbering. Visual inspection of the exposed phosphate and expert judgment of the "grade" analysis, aided by a "biting" test to reveal presence of unwanted silica, furnished most of the information required. All this might be helped by a few samples sent to the local chemist† who supplemented his income by judicious trading or tanning a few bear skins. The extra curricula activities did not affect the accuracy of the analysis which hold up even under present day standards. Some shot and core drilling was done in Hickman County, mostly for the limestone-like blue Phosphate deposits. The next step was the use of a 4-in. posthole auger, hand operated as described by Guenther, followed by a completely mechanized rig, as described by Pickard. Both these methods are practically adapted to the prospecting of the relatively soft brown rock deposits at moderate depths of clay overburden. For prospecting in areas of deeper overburden, such as are often found in Hickman County, up to 150 or even 200-ft depths, a modified core-drilling method is described by Guenther. Johnston describes a special diamond-drilling technique, developed by TVA, to penetrate flint horizons, which was adopted by the International Minerals in chemical corporation to prospect in Hickman County where deposits had previously been prospected at considerable expense and with difficulty, by small, temporary, hand-dug shafts.

Jan 1, 1948

By Frank Yu, Bob Fukuhara

"The Stillwater mine is a 3,000 tons/day platinum/palladium underground mine and flotation concentrator located in the Beartooth mountain range in south-central Montana. The site elevation is 5,000 feet above sea level providing a climate with pleasant summers and cold winters. The winters are particularly characterized by very strong winds.The mining methods at Stillwater had been variations of overhand cut-and-fill and some blast-hole stoping. Until construction of the paste back-fill plant, mine back-filling was being practiced using classified hydraulic sand-fill methods. Where higher strengths were necessary, cement was added to the hydraulic fill, however, excessive quantities were necessary due to significant losses with the water drainage from the comparatively low-density fill. There was a need for higher strength back-fill with reduced cement content to augment the hydraulic-fill process.In early 1998, Stillwater Mining Co. commissioned AGRA Simons (then H.A. Simons) in a joint venture with The Industrial Company, TIC, to design and construct a treatment facility to re-process the mill flotation tailing, incorporating the following process alternatives:Produce 100 tph of low strength paste with unconfined compressive strength of 25 to 50 psi,Produce 100 tph of high strength paste with unconfined compressive strength of 100 to 125 psi,Direct all of the excess mill tailing to the sand-fill plant,While no paste is being produced, pump all of the mill tailing to the sand-fill plant,While no paste is being produced and the sand-fill silos are full, direct the mill tailing to the tailing pond.The paste backfill plant was therefore to be designed to produce the two different types of backfill paste as well as have the function of being the distribution center for the mill process tailing .Moderate to high slump pastes would be required because of the comparatively long horizontal transport distances, up to 8,000 feet, and the requirement for a low angle of repose to fill the stope evenly without numerous discharge points."

Jan 1, 2000

By M. Stephton, L. A. Cornish, R. Süss, N. B. Maledi, J. H. Potgieter, L. Chown

In today?s gas turbines, the emphasis is on saving energy and reducing the amounts of pollutants emitted. This can be attained only by designing alloys with higher melting points and the capability to retain mechanical integrity at increased temperatures. The development of nickel-based superalloys (NBSAs) has reached its limit, as the alloys are operating at critical temperatures close to their melting points. Further increase in the operating temperatures will result in dissolution of the strengthening phases and even melting. Recent trends are towards developing materials that are adequately strong but have much higher melting points and corrosion resistance than the NBSAs that are currently in use. Studies conducted on Pt alloys with similar structure to the NBSAs have presented mechanical results that are promising. This has led to further development of these alloys as a replacement for NBSAs. The operations of gas turbines are usually limited by hot corrosion, which could lead to catastrophic failures. Increased temperatures have an adverse effect on the corrosion of the alloys by making the environment more aggressive. Hence, during a material selection process, the corrosion behaviour of any selected material for a highly specialized application such as gas turbines needs to be assessed. Generally, coatings are applied to combat degradation by salt deposits, hence coated and uncoated NBSAs were selected as benchmark alloys. Corrosion mechanisms and kinetic studies of the Pt alloys were conducted. High temperature hot corrosion (HTHC) tests were conducted at 950°C for540 hours. Analysis of the corrosion products was conducted using a Raman spectrometer, scanning electron microscope with energy dispersive X-ray spectroscopy (EDS) optical microscopy, and X-ray diffraction study of the phases that formed. Both coated and uncoated NBSAs failed under the test conditions. Samples were covered with a porous non-adherent greenish layer which is characteristic of NiO. Pt alloys displayed superior corrosion properties compared with the benchmark alloys.

Jan 1, 2006

By S. A. Scott

Mintek developed the MinataurTM leach-solvent extraction-precipitation technology as a cost effective, easily operated alternative to conventional gold refining processes. The technology was first commercialized at the Harmony Gold Refinery in 1997 to produce 99.99 per cent gold product and has subsequently led to development of various value-addition steps including the casting of various investment bars, gold wire drawing and gold potassium cyanide powder production. In addition to refining gold to high purity, if an appreciable amount of silver is present in the feed material it is also refined to 99.99 per cent purity. The major advantage that the Minataur? technology has over other gold refining processes is the relatively low gold lock-up and reduced operating costs. The operating cost1as at April 2001 for the expanded Harmony refinery (24-ton per annum gold production) was approximately half that of conventional smelting and toll refining. The extractant employed for solvent extraction is relatively cheap and highly selective for gold, making the technology attractive in situations where significant quantities of platinum group metals or base metals are present.

Jan 1, 2004

By H. Ranjbar

The Darrehzar porphyry Cu deposit is situated in the Urumieh-Dokhtar magmatic suite of Central Iran. The REE and trace element data suggest that the deposit lies within a continental margin setting. Phyllic and propylitic alteration are pervasive in the area but potassic and argillicalteration are not readily recognized on the surface. This is possibly the result of super gene weathering of the surface rocks or because of an intense phyllic overprint. Poor soil development and abundant outcrop make the area suitable for a case study of lithogeochemical exploration technique for Cu deposits. A total of 262 rock samples was collected over the area and analyzed for 15 elements. The geochemical data cor-relate with the mineralogical composition of the rocks with the phyllic zone being marked by high-er concentrations of Si, Al, K, and by a high sericitization index while Ca, Mg, Sr, total Fe and Mn are more abundant in the propylitic zone. The lithogeochemical study indicates a metal zonation from a Cu + Mo-rich core to a Zn + Pb ± Ag-rich outer zone. Principal component analysis is useful for separating element associations, which in turn reflect the alteration halos. Principal components 1 and 2 depict alteration zoning, where-as 3 shows an association of Cu and Mo, that roughly defines the mineralized area.

Jan 1, 1997

By J F. H Thompson

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. Mineral exploration and mining are challenging businesses. Remote and at times harsh conditions have always made it difficult for exploration, but modern explorers also have to deal with cover, numerous technologies, an explosion of data and critical early community engagement. Mining deals with the reality of moving and breaking thousands of tonnes of rock each day to extract what can be a very minor component of economic value, and, furthermore, society expects that this will be done in a clean and sustainable manner. The exploration and mining challenges appear disparate, but they are intimately related.Although not widely appreciated, both exploration and mining have a long tradition of innovation. Over the last 50 years, major step changes in exploration have resulted from radical advances in our understanding of ore forming processes, new geophysical, geochemical and remote sensing technologies, and new ways to integrate and interrogate data. Over a more extended period, close to 100 years, mining has developed bulk surface and underground methods, selective extraction through flotation and leaching and global positioning system–geographic information system control systems that collectively facilitate mining at a massive scale. And yet, in spite of these successes and the boom that we have enjoyed in the last ten years, the industry is under pressure and the need for innovation and change is paramount.The major drivers for innovation are the need for increased quality in discoveries and mines and the need to interact effectively with communities and jurisdictions such that the benefits of quality mines are recognised and enjoyed widely.We are still making new discoveries around the Pacific Rim and elsewhere, but many argue that the quality – grade and accessibility – of these discoveries is decreasing. The net result is that explorers are delivering resources and reserves for development at lower grades and with higher capital and operating costs than current operations. For mining, the increasing age of many existing operations contributes to increasing costs, which, when combined with decreasing cut-offs and lower grades, also results in declining quality. The combined picture does not look good.Just as the pressure to improve performance and margins in the face of declining inputs increases, we are simultaneously faced with increasing societal demands for improved environmental performance and sustainable practices. This is most apparent at the local, community level, where opposition ultimately leads to delays or even cancellation of new projects. Quality is again the issue – quality of the initial and ongoing engagement and quality of the proposed mine in terms of environmental and economic performance.CITATION:Thompson, J F H, 2015. Exploration and mining – the need for innovation , in Proceedings PACRIM 2015 Congress, pp 45–48 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

By G Fahey, S Rose

"Mining geology as a defined profession is only about 100 years old. The successful modern mine geologist needs to be a multidisciplinarian, but also needs to maintain a focus on the key outputs of the role. The technical skills needed in the role have increased as mining methods move to increasingly mechanised techniques. As well as being the guardian of the orebody and ensuring minimal dilution to expected ore grades, the mine geologist should be competent in the 12-point mine geology process. The mine geology process should include:a statement of purpose (a ‘mission statement’)geological mapping/logging system that supports consistent and regular geological data collection, storage, and interpretationsampling system that can produce representative samples and fits in with the mining scheduleassay database with relevant controls to ensure only ‘clean’ data is loadedsimple quality assurance / quality control (QA/QC) system for samples and assays, with a response process to react to out of specification resultsconsistent method of exporting, visualising, processing and interpreting assay data to create mining blocksdevelopment sign-off system so that all development and stoping is controlledproduction tracking system to monitoring and reporting what ore and waste volumes have been moved from the face, to any intermediate stockpiles, the run-of-mine (ROM) pad and into the crusherreporting system for daily, weekly and monthly reporting of tonnes and gradesdocumentation so that the grade control system has simple, but effective descriptions of how it works, who has responsibilities, and authorities, and be easily maintainedreconciliation system to compare resource and reserve to grade control and to mined and milledtraining system so that the geology team can quickly become competent.In this paper, the authors discuss the requirements of each point, and comment on common shortfalls observed by them over several years’ experience on producing mines worldwide.CITATION:Rose, S and Fahey, G, 2014. Modern mining geology, in Proceedings Ninth International Mining Geology Conference 2014 , pp 461–466 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Aug 18, 2014