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By J. G. Haymes

This report by the Bureau of Mines is the first of two proposed papers on evaluation of spectrophotometric, spectrographic, polarographic, and other analytical methods for quantitatively determining impurities in high-purity tungsten. Some of the methods described are standard methods that have been successfully applied to determine low-level impurities, several are modifications of known methods, and some procedures are entirely original. The Bureau of Mines is actively engaged in tungsten research because tungsten has an extremely high melting point, in fact the highest of any known metal. The metallurgist must know the content of impurities in tungsten because of the marked effects even micro amounts of impurity elements have on its physical properties. The Bureau procured a number of analyzed samples of above-average purity from research laboratories of companies engaged in production and fabrication of tungsten. These samples were investigated by the analytical procedures of those companies for several metallic impurities. Subsequent analytical laboratory determination of impurities in these samples agreed with the analyses as reported. With this assurance that analytical methods were basically accurate for metallic impurities, procedures for the determination of several of these elements were modified to lower the limits of detection and increase the sensitivity of methods. Carbon and the gases hydrogen, nitrogen, and oxygen were determined by standard instrumental methods, modified to provide greater sensitivity for reliable determinations when content of these elements was low. After the reliability of the modified procedures was affirmed, they were used as a product evaluation guide in the development of a vapor-plating technique for the production of high-purity tungsten. The following list of elements can be determined by one or more of these methods: AI, B, Be, Ca, Co, Cr, Cu, Fe, Mg, Mn, Mo, Ni, Pb, S1, Sn, Ti, V, and Zn. In addition, a vacuum-fusion method for the determination of H, N, and 0, and a conductometric method for carbon are described. Lower limits of determination and detection for each element listed are given.

Jan 1, 1962

By G. F. Kuncir

The analysis described herein evaluates the Bureau of Mines Program for Advancing Mining Technology - Oil Shale in terms of the economic benefits which may be derived for the Nation as a result of its successful research and development efforts. On the basis of postulated oil shale production scenarios, benefit-cost ratio indicators are computed for the program elements as they apply to surface, underground, and modified in situ oil shale mining systems. Eight value indicators are used to measure the Program's beneficial impact on the future oil shale industry in relation to planned research and development costs. These are: capital cost savings, operating cost savings, labor savings environmental quality maintenance cost reduction, reduction in production costs, byproduct production benefits, total production benefits, and additions to recoverable reserves. Program costs are aggregated from 1974 through 1987 and major benefits are accrued from 1982 through 2040. Both cost and benefit streams are discounted to mid-1975 present value.

Jan 1, 1977

By John Lindsay

"Although diamond mining is a relative newcomer to the Canadian mining industry, with the first diamond mine coming on stream in 1998, Canada is already a significant producer of high quality diamonds. This paper will review diamond production trends and highlight some of the projects currently under development, which have the potential to enhance Canada’s role as a significant diamond producer.Diamond recovery plants generally incorporate well-established mineral processing and recovery techniques, with issues such as product security, cut-off sizes, and diamond preservation becoming important considerations when developing process flowsheets. A diamond processing plant must achieve three key objectives, namely:• Liberation of the diamonds from the host rock;• Separation of the heavy minerals, which include the diamonds, from the host rock;• Recovery of the diamonds from the heavy mineral concentrates.Processing technologies and equipment commonly utilized in diamond processing plants will be reviewed and some of the significant issues associated with each option briefly discussed.Typical process flowsheets will be presented.Finally, an overview of De Beers’ Victor diamond project, located in northern Ontario, will be provided. This potentially significant diamond producer is currently at a pre-feasibility stage of development.DIAMONDS IN CANADAWorld Diamond ProductionCommercial diamond mining commenced in earnest with the discovery of the Kimberley diamondfields in South Africa in the late 1800s, and this resulted in a dramatic increase in the supply of diamonds. As can be seen from figure 1, world diamond production, mainly from South Africa, Angola, Congo, and Namibia, remained relatively constant through the early 1900s until the development of the large Russian kimberlite pipes in the 1950s. Production increased again in the 1960s and 70s with the development of the Botswana mines, but the most significant increase in global production came from the Argyle mine in Australia, which came on stream in 1983 and produced a peak of almost 43 million carats in 1994, representing approximately 40% of the world market. Production from Argyle has since fallen-off as grades have declined and the strip ratio has increased with the deepening of the open pit."

Jan 1, 2003

By Timothy P. Smirnoff, Tracy K. Lundin

INTRODUCTION The City of Phoenix, Arizona is located in the Phoenix Basin watershed which is prone to flash flooding several times each year. The runoff from these storms moves from the mountains in the north to the Salt River in the south. An extension of Interstate Highway 10 (1-10) will pass through the city east to west to form an Inner Loop through the downtown business district. PROJECT DESCRIPTION The I-10 Inner Loop extension will be a depressed roadway which would intercept the surface drainage of the Phoenix Basin and separate the watershed into two regions. To prevent flooding of the depressed roadway, runoff storm water collected from the northern half of the drainage area will be conveyed beneath the roadway to its natural outlet at the Salt River. A conveyance system composed of pressure tunnels beneath the city, shown in Figure 1, was proposed to achieve this goal . Table A presents the prominent features of each of the tunnels. This paper will describe geologic and engineering parameters specific to Phoenix which were used in the design of a series of tunnels to convey storm water from the I-10 Inner Loop to the Salt River. The design of tunnel initial and final support is described along with support and construction methods used by the Contractor.

Jan 1, 1985

The importance of timbering, not only from a financial point of view but from an actual mining point of view, is so often overlooked or slightly glossed over by the average expert and investor, that I have thought it would prove interesting to go into the matter and to invite discussion upon the subject. We will first take small veins, or reefs as they are termed in some mining countries; and by small veins it is intended to denote fissures from a few inches to three feet. The ore body is supposed to be confined within well defined walls free from gangue matter, unless the casing can be defined as such. Now, if the walls are smooth and moderately hard, no timbering is required other than the stulls, which are braced from wall to wall in order to form platforms or stages to stope from. Should the reef from wall to wall prove payable, or should the vein be of a character to prohibit cleaning or sorting; and it be determined to send the whole of the stone to the, reduction works, the stuUs should be left in place until the section or block of ground is worked out, in order that if a weak spot in the walls (especially the hanging) occur, it would be possible, without any particularly extra expense or difficulty often times accompanied by danger to brace and secure the slabs. After the block became entirely stoped, it would pay where labour was cheap to remove the majority of timbers to stull another section.

Jan 1, 1901

By O. C. Blade

The term "Ichtnyol" is a name applied loosely to certain preparations used in pharmacy. These preparations do not occur as such in nature but are manufactured by various chemical processes. Ichthyol is the name trademarked for a product manyfactured by the Irhthyel-Gescllschaft (Cordes Hermanni & Co.) of Hamburg, Germany, and marketed in thin, country by Merck & Co., Inc., (5, 86, 87)3/. Although used in the literature rather loosely, the correctly applied word refers to the product obtained by sulphonating and then neutralizing with ammonia a distillate from the oil retorted from a certain high-sulphur bituminous shale found near the village of Seefeld in the Austrian Tyrol. Due to the fact that fossils of fish and marine animals occur in the limestone associated with the bituminous shale, these deposits have long been known as, the "lchthyolite schistc of Seefeld" ( 55) . The Greek word "ichthys"" for fish and the Latin word "oleum" for oil are the words from which the term is derived. The crude, tarry shale oil, whose distillate is the raw material for the sulphonation process, has been referred to since the Middle Ages as "Dürsten" or "Tirschen" oil, and the term "ichthyel oil" has been used occasionally in the literature to designate the retorted crude oil (92, 93, 106, 117). The first application of the name "Ichthyol" to a particular product is credited to Schröter (35, 129). Various names for products manufactured by sulphonating bituminous distillates have been coined, and in some of these names the root from the word ichthys has been retained. Some of these names can be found in New and Nonofficial Remedies under the heading, Sulphoichthyolate Preparation, and Substitutes (5).

Jan 1, 1938

THE Australian States and New Zealand have for many years provided instruction in mining, metallurgy, geology, and their allied subjects through their Universities and Schools of Mines. Though such education has been provided at considerable expenditure, there is no legal recognition whatever given to the holders of degrees, diplomas, or certificates granted by the authorities controlling these educational institutions. Certain of the, Australian States and New Zealand require, however, that mine managers and other officials employed by the mining industry shall 'hold' certificates granted by their respective Mines Departments.The position at present is that each educational institution is practically a law unto itself, and therefore in many ways there is a want of uniformity amongst institutions all aiming at the same result the training of mining men. The object of this paper is, in the first place, to point out certain aspects of this want of uniformity, and thereby how disabilities accrue. Some points in connection with the granting of State certificates will also be...

Jan 1, 1915

Exploring the Breakage Environment in Mills with Discrete Element Methods

Sep 13, 2010

By M. Maccagni, J. Nielsen

"Engitec developed the EZINEX® Technology some years ago to recover zinc from oxidized secondary sources. This process works at neutral pH and can take into solution any kind of metal, but iron is rejected and remains in the leach residue. Engitec has also developed the FLUOBORATE System, which is able to recover lead and copper from relevant concentrates. Some iron is leached into solution, but it is controlled through a solution purification bleed treatment. In this paper, we present the two above mentioned technologies. They are very different with regards to the chemical environments and the methods used to control the build-up of iron in solution, but both systems are suitable to treat iron bearing feeds.INTRODUCTIONIn the design of hydrometallurgical processes, the most important issues are the water balance, the filtration and the control of impurities. This is particularly important when the process includes an electrowinning unit. Iron has been one of the most problematic elements to remove, especially in acidic environments.Engitec Technologies has developed several hydrometallurgical processes divided in two different electrolyte lines: the Fluoborate Technology for the recovery of lead and copper from primary and secondary sources and the Ammonium Chloride System based on a chloride electrolyte for the recovery of different non-ferrous metals, among which zinc and lead are the most important. In both cases, iron is present in the feed and needs to be eliminated from the solution. It is not a problem for the quality of the metal produced, but when present in solution, it consumes the basic electrolyte reducing its free concentration which is very important both for both the leaching and electrowinning unit operations. Both process systems are very peculiar, the fluoborate case being much more intriguing."

Jan 1, 2016

By Andrew Bamber

Between the early 20th Century and the present, the production of mined copper ore has increased from tens of millions of tonnes per annum to several billion tonnes per annum, an unprecedented increase. Contemporaneously, the average grade of mined copper ore has declined from over 2% to approximately 0.5%. Again, in parallel, the price of copper has increased dramatically to reflect the increasing cost of extracting and beneficiating such large amounts of low-grade ore. Within the period the copper price however exhibited several periods of intense volatility, driven by interrelationships between demand and supply, themselves strongly driven by periodic industry developments in the fields of exploration, ore extraction, mineral processing and extractive metallurgy. It is notable that these periods of intense innovation exhibit a strong correlation to preceding periods of price, demand or production volatility. This paper examines key trends in each theme between 1900 and 2018 and draws strong conclusions as to the interrelationship between them. INTRODUCTION The production of copper metal has increased from around half a million tonnes per annum to over fifteen million tonnes per annum over the course of the 20th Century. Contemporaneously, the average grade of copper ore mined has declined from over 2% to approximately 0.5% copper by weight. As a result, the volume of Run-of-Mine (ROM) copper ore required has increased from around ten million tonnes per annum to over a five billion tonnes per annum over the period, an unprecedented increase. The adage is that demand drives supply, that prices rise in times of high demand and/or short supply, and that prices fall when supply catches up with demand. The market sellers in biblical times knew this well; mediaeval market sellers equally. Dutch tulip sellers in the 1600’s experienced both in extremis — much to their dismay — and the great industrialists and early capitalists of the industrial revolution knew this also. Mining recently went through a cycle where investors and producers both believed that the “old” rules did not apply any more and that the industry was in a “supercycle” where prices would continue to rise on the back of increasing demand. However, as the GFC of 2008–2011 showed, this was not to be. Another adage says that we constantly innovate to lower costs of production. Is this true? Do we only innovate to lower cost? Has the true cost of producing copper actually gone down over the century? Or are there other balancing forces at play? Herb Kellogg, in his Centenary address to the American Institute of Mining Engineers (now SME), categorized two types of innovation: ‘Bigger and Better’, and ‘New Process’ (Kellogg, 1970). ‘Bigger and Better’ allows increased production at presumably lower cost; ‘New Process’ supports the same result at presumably the same scale, but at significantly enhanced efficiencies and (therefore) lower cost. It is suggested that both types of innovation are constantly and interchangeably required to achieve the kind of scale-up, at achievable operating and capital cost that the industry has achieved over the period. What can be shown, over this last Century and a bit, is that supply and demand are indeed inextricably linked, price and demand are linked, but so are price and cost of production. And the innovation required to sustain that weaves in between them all, cost-effectively increasing production capacity or lowering the cost of production at the same throughput, and sometimes both.

Jan 1, 2019

By C. J. Van Treeck

PGE concentrations of 18 g/t occur in the pyroxene rich rocks at the Union Bay Alaskantype complex. This PGE enrichment is hosted in magnetite veins. These veins cross magmatic layering and have an irregular morphology in both outcrop and thin section. Fe-Ti oxide geothermometry suggests that this mineralization took place between ~700-400°C. A variation in the amount of ilmenite and Mg- Al spinel exsolution in magnetite correlates with temperature estimates, lower temperature magnetite has less exsolution. Hydrous silicates form an alteration envelope around magnetite veins with a formation temperature of <575oC, vary with temperature, and contain appreciable amounts of Cl. Interaction of a PGE-Fe-Cl rich fluid with clinopyroxene increased the fluids pH and decreased PGE and Fe solubility depositing a PGE enriched magnetite within the Pyroxenites and Olivine Pyroxenites of the Union Bay complex.

May 1, 2003

By S Vianna, K Caldwell, R Silva, T Olson, D Bell

Studies to enhance the FLSmidth forced air machine through changes in the design, showed important improvements through changes in the number of Rotor blades, stator designs, rotor air distribution and other designs features. The main outcomes from this study highlighted that increasing the number of rotor blades increased the selectivity while decreasing power requirements while stators with slots have better results in terms of recovery, flotation efficiency and selectivity than without slots.Also the rotor air distribution makes a difference in the design when comparing different distribution criteria whilst keeping all features of shape and number of blades etc constant. At the most efficient rotor air distribution design, copper recovery reached one of the highest values while keeping good selectivity. The possible explanation for that is the increase in the pump capacity indicated by the increase in the specific power.It was seen as significant that reduction in specific power for some designs tested compared with the then current standard design had an average of 30% less power consumption.As a result, FLSmidth was able to identify new designs that decreased power and improved recovery, as well as, identifying some designs that specifically improved fine and/or coarse particle recovery.CITATION:Silva, R, Caldwell, K, Bell, D, Olson, T and Vianna, S, 2013. FLSmidth flotation developments - Dorr Oliver machines, in Proceedings MetPlant 2013 , pp 413-430 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 15, 2013

By Wayne Rogers, Kell Monro, Arthur Pacunana

The Phu Kham Copper-Gold Operation (PKM) is a large-scale open pit mine located in northern Laos. It was developed and is operated by Phu Bia Mining Limited (PBM) a Lao-registered subsidiary company of Australian incorporated, PanAust Limited. Production commenced at Phu Kham in 2008. Since the second half of 2016, there has been a significant increase in ore hardness and this has negatively impacted the PKM concentrator and resulted in lower SAG mill throughput rates. Over the remaining life of mine, the changing ore body and increase in ore hardness is forecast to continue as the pit deepens and the availability of softer blending ores reduce. To manage this risk, PKM initiated a Hard Ores Management Program to determine the most effective way to improve the mill throughput of harder ores. This involved conducting a number of innovative and process control driven blasting trials to optimize run-of-mine (ROM) fragmentation and other blasting outcomes. From 2016 to 2017, the performance of high powder factor blasting, electronic detonators and fast timing, high velocity of detonation (VOD) explosives, double-priming, and deck blasting, were individually and systematically assessed. The success of each blasting trial was then based on a ‘value for money’ criteria. This criteria is a cost / benefit analysis that weighed-up the additional cost to implement the trial against the measured improvement in mill throughput. Electronic and high VOD 90:10 emulsion:ANFO blasts were determined to have the best value for money, achieving an increase in mill throughput of 54% compared to baseline. This paper discusses how the implementation of an innovative and process control driven blasting trial methodology was able to successfully manage the hard ore challenges at PKM. In addition, this success was achieved without any major cost implications, safety incidents or process plant set-backs.

Jan 1, 2018

By Helen D. Robinson

The seawalls that surround Ellis Island were constructed in the early 1900s and now show varying degrees of deterioration. An innovative approach to the structural repair of the seawalls was developed, which consisted of the use of micropiles for stabilization of vertical and horizontal seawall movements. The micropiles were installed through the existing seawalls and penetrated through a thick overburden, consisting of soft alluvial deposits and relatively hard glacial till, and were bonded into Manhattan Schist. Drilling of the micropiles often encountered timber and other obstructions. The selection of micropiles for stabilization of the seawalls offered significant advantages over other foundation systems and over alternative soil improvement techniques. They allowed drilling through a variety of materials without the need for significant retooling or changes to the drilling procedure. This reduced the impact of foundation construction on the sensitive historical landscape and structures, and prevented the need for significant foundation work from the water side of the seawalls. In addition, micropiles offered relatively high installation rates and flexibility to adapt to the varying conditions along the seawalls.

Jan 1, 2008

On the Hauraki goldfields, within the limits of Cape Colville Peninsula, the Paheozoic rocks are confined to the district north of a line drawn from Mercury Bay on the east coast to Rocky Point on the shore of the Frith of Thames. South of Kennedy&apos;s Bay they are developed on the east coast only at Kuaotunu, at which place gold mining is carried on in sandstones and slates of this age. Between Tapu Creek and Coromandel there is, along and adjacent to the shore of the gulf, a very considerable development of PaJreozoic and in part of Trias rocks, and between the Tiki Stream and the northern end of Tokatea Hill, along the western slope of the main range, lies the special area of the Palreozoic or carboniferous rocks that have more particularly to be dealt with in this paper. The same formation has a large devolpment between Cabbage Bay and the northern slopes of Moehau, and appears to the water marge on both sides of this part of the peninsula.In this part they are of special interest as having, on the west spur of Moehau, a considerable variety of dyke rocks intruded into the sedimentaries, the interest in which is increased by the fact that these dykes theIllselves are of Palreozoic age and correspond to the dykes that are so&apos; abundant in the Tokatea-Tiki area. It is this Tokatea-Tiki area as a goldfield, and its rocks as distinguished from later volcanic&apos; products&apos; on other parts &apos;of the peninsula...

Jan 1, 1903

By Mark Fernald, Christian O’Keefe, John Viega

"In this presentation, the SONARtrac™ technology platform will be described. CiDRA's proprietary clamp-on, passive sonar array-based flow meter technology performs two independent measurements – flow rate and fluid characterization. Firstly, the meter provides the volumetric flow rate of the mixture by measuring the speed at which naturally occurring turbulent structures convect with the flow past an axial array of sensors. Secondly, the meter uses similar sonar-based processing techniques and naturally occurring sound in the process fluid to measure entrained air levels. The result is a unique ability to measure the flow rate and entrained air level of most fluids – clean liquids, high solids content slurries, and liquids and slurries with entrained air.Also to be presented is the application of the sonar-based technology platform in a variety of oil sands processes, hydrotransport, and minerals beneficiation applications. In particular, difficult slurry flow measurement and control in the areas of comminution and flotation such as mill discharge, hydrocyclone feed/overflow, final concentrate, thickener discharge, and tailings will be discussed. In addition new real time maintenance free process measurement capability will be presented in the areas of entrained air in slurry, collection zone gas holdup (?g), and slurry velocity profiling. The operational advantages and value of these measurements, even in the presence of scale buildup, will be discussed.INTRODUCTIONFlow measurements in the mineral processing and oil sands industry suffer from the limitations placed by previously available flowmeters including the commonly used instruments such as ultrasonic meters, magmeters, turbine meters, orifice plate meters, vortex flow meters, Coriolis flow meters, and venturi meters. The desire or requirement to make a non-contact measurement that is accurate and robust, and can be performed on practically any type of fluid within practically any type of pipe has driven the creation of a new class of flowmeters. This new class of flowmeter technology utilizes sonar-based processing algorithms and an array of passive sensors to measure not only flow, but also fluid composition."

Jan 1, 2007

By A. Amiel

Tarkwa Gold Mine is owned by Gold Fields Ghana, IAMGOLD and the Government of the Republic of Ghana in a 71%, 19% and 10% ratio. The mine is operated by Gold Fields Ghana. This large, low-grade, open pit, gold mining operation is located in Tarkwa, in the Western Region of Ghana, approximately 320 kilometres by road, west of Accra, the capital of Ghana, West Africa. In the Financial year ended June 2007, the operation mined a total of 108 million tons of which 22 million tons was ore. The mined ore is processed through three gyratory crushers supplying two heap leach pads (north and south) and a carbon-in-leach (CIL) plant. Before the 6 Sigma project commenced, the current fragmentation was resulting in sub-optimal feed size to these crushers. It was decided to use 6 Sigma methodology to improve the fragmentation. A defect was defined as a fragmentation analysis indicating less than 95% passing 750 mm. The objective was to improve fragmentation in order to achieve a constant throughput to the north heap leach crusher of 1500 t/h, a 5% increase in pit loading efficiency and a 50% decrease in rock breaker hours, equipment damage costs and in-pit sheeting costs respectively. However, this was not to be achieved at the expense of grade control as Tarkwa is exploiting a low grade, high volume deposit and therefore ore dilution must be kept to a minimum. This paper is intended to take the reader through the various 6 Sigma phases of the project (define?measure?analyse ?improve?control), which have resulted in a 10% reduction in loading times, of which half has been attributed to improved fragmentation, as well as a substantial increase in blasted stocks. The focus has been on both drilling and blasting parameters as both processes had to be taken into account. These parameters are technical but personnel factors were also identified and dealt with as they arose. In order to measure the impact of any change in the process parameters on the fragmentation size distribution, cameras have been acquired. One has been installed looking into the bowl of the north crusher and the other one was dedicated to field observation, of individual blasts. Both are used for ongoing fragmentation analysis. At Tarkwa, mining efficiency is strongly dependent on good fragmentation as well as the presence of unblasted ?toes? on the pit floors. Crusher throughput depends on an acceptable ore fragment size. Compliance with plan for actual hole depths was temporarily monitored by manual hole dipping, but this is now being replaced with a fully automated drill data management system developed by Sandvik and Modular Mining. The Six Sigma methodologies, using control charts based on data collected in the field, allowed the mine to improve methods for the control of blasted material. It also enforced the implementation of a quality control programme encompassing the entire drill and blast process.

Jan 1, 2008

By A Vigar

Siliceous float sampled in the Wafi River by CRA Exploration in 1977 assayed 22 g/t Au and 89 g/t Ag. Follow up in 1979 led to the discovery of outcropping mineralisation now known as Zone A. Soil sampling in 1980 and 1982 outlined a 350 m by 400 m area of >1 g/t Au at Zone A and smaller areas at Zones B, C and D. Thirty-one diamond holes were drilled between 1983 and 1986. Elders Resources continued evaluation of Zone A under a farming agreement between 1988 and 1990. Mineralised diorite porphyry was discovered in 1990 by drilling conceptual targets 500 m to the NE of Zone A. Evaluation of this copper-gold porphyry became the main focus of exploration for the next five years and a substantial resource was outlined within a single, discrete body. A review of the paths to project development in late-1995 highlighted the need for increased resources via a second mineralised porphyry and/or an additional resource of Zone A size to make the project viable. It was concluded that the greatest immediate potential for increasing the resource inventory was at Zone A itself where the mineralisation was open in all directions. Detailed mapping and drill core logging lead to the geologic and structural models being revised in early-1996. The objectives of the 1996 drill program were to extend the Zone A resource, to test for continuity of mineralisation westwards to Zone B, to better define the controls on gold mineralisation and to delineate high-grade blocks amenable to selective mining by infill drilling and 3D orebody modelling. The last drill hole of 1996 intersected 30 m at 4.6 g/t Au from 273 m in WR147, deep in the western limit of Zone A. This intersection gave impetus to continue drill testing towards Zone B. In April 1997, hole WR154 was drilled 100 m to the west of WR147 and intersected 20 m at 8.5 g/t Au and 70 m at 11.0 g/t Au at similar depths near the diatreme contact. Drill hole WR155 was then drilled 100 m to the west of WR154 and intersected 86m at 5.7 g/t Au and WR159 drilled 100 m to the south of WR154 intersected 36 m at 9.2 and 50 m at 4.4 g/t Au. A significant zone of essentially blind, high-grade gold was discovered beneath the dipping flank of a poorly mineralised diatreme in what became known as the Link Zone. The long history of evaluation has been driven by the conviction of a dedicated team that a mineralised system of the size and complexity of Wafi with strongly anomalous gold in outcrops over the entire Mount Golpu area must contain economic mineralisation hidden within it. The keys which redefined the direction of exploration and lead to the discovery of the blind, high-grade gold Link Zone were, in our view, the critical review of the project status, detailed geological and structural studies to define clear exploration targets and the necessary funding and persistence to carry this through.

Jan 1, 1999

During the last 125 years, the steel industry has witnessed revolutionary changes in the process of steelmaking. The Bessemer process was the predominant steel production technology during the last two decades of the 19th century. The open hearth process accounted for the lion&apos;s share of world steel production for six decades from 1910 to 1970. With the appearance of the LD process on the industrial stage in 1952, the importance of open hearth process declined and currently the basic oxygen processes are contributing more than 60 per cent of the world steel production. The LD process also led to the development of several other oxygen blown processes such as LDAC, OLP, OBM, QBOP, EOF, Clc.

Jan 1, 1999

The material presented in this paper describes experimental work to determine the effect of variations in suction nozzle design upon inlet flow conditions. Four entrance profile shapes were examined under controlled conditions of slurry flow and it was found that the straight ended nozzles had consistently higher entrance losses than the straight taper or the ellipse, and that the circular arc profile nozzles were the most efficient. Subordinate considerations were the measurement of the quantities and the forces involved.As the work progressed, three distinct phases in the pattern of flow were apparent and the static pressures in each were carefully examined. An inlet zone was found to be unstable in changing boundary conditions, a transition zone was largely independent of slurry density and in a zone of stability the pressures were found to be directly related to the characteristics of the flowing pulp. In this zone pressure measurements were reproducible within &#177; 2 per cent regardless of changing boundary conditions.The effect of varying the &quot;1&quot; parameter of nozzles with a part circular entrance profile was examined and it was found that flow conditions approaching the ideal were obtained when the radius of curvature was between 0&#183;40 and 0&#183;550.

Jan 1, 1966