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By Charles Behre

THIS paper deals with recent geologic studies in the slate belt of Northampton, Lehigh and Berks counties, Pennsylvania. The work was conducted under the auspices of the Pennsylvania Topographic and Geologic Survey. Three years have now been spent in detailed consideration of the economic geology of this region. In the field, particular attention was paid to the bearing of geology on quarry development and property valuation and the object of this paper is to summarize the results from that viewpoint. Excellent studies of a somewhat similar nature have already been carried out by Bowles,1 but with the emphasis upon the details of quarrying and fabricating methods, rather than upon the geologic relations. THE NORTHAMPTON-LEHIGH-BERKS DISTRICT Location The region here discussed lies in east-central Pennsylvania and extends southwestward from Delaware River, on the New Jersey line, to the Schuylkill in north-central Berks County. It is an elongated belt occupying the northern sections of the three counties mentioned and lying along the southern edge of Blue Mountain. Its length is about 50 miles and its average width five or six, though in places it attains a maximum of 10 miles.

Jan 1, 1928

By C. N. Harman

Steel is the most versatile material which has made the progress in every aspect on this earth possible. There are hundreds of varieties of steel because for each application it has to be made with specific properties to get the most optimum usage. It is well known that the basic constituent of steel is iron. But it is the proportion of other elements in it, which give each type of steel certain specific properties. These elements are added in liquid iron inform of Ferro alloys to get the desired composition and properties. Thus, Ferro alloys are important additives in the production of steel. It can be said that no steel can be made without use of one or more of the several Ferro alloys. They form the backbone of steel. Thus, the Ferro alloys industry is vitally linked for its growth and development to that of the steel industry. Ferro alloys industry in India has never been globally competitive, despite its rich ore deposits and low-cost manpower, essentially due to a) Insufficient availability and high cost of electric power b) Increasing ores and reductants cost c) Non-availability of low ash, low phos. coking coal in the country for the production of desired coke with low ash, and low phos. contents, making import of such coke at a high cost imperative d) High-cost and insufficient infrastructural facilities (both road and rail) for rapid transportation of ore from mines to plants e)Stiff competition from producers and exporters of Ferro alloys in other countries like South Africa, Kazakhstan, China, Russia, Australia etc. due to global trade agreement which has made drastic reduction in customs duty on imports necessary. f) Wide fluctuations in the International price of Ferro alloys depending on demand versus supply. To over come these challenges plus adhering to stringent pollution control norms innovations are inevitable in the process technology, and plant equipment design, along with frequent changes in product mix, to be more cost-effective. An attempt is made in this paper to address the innovations that took place in the past and those that further need to be made, considering the future of this industry.

Jan 1, 2007

By Frederik W. de Klerk

INTRODUCTION During the past 40 years, there has been in the United States of America and other industrialised Western countries a distinct displacement in the procurement of minerals from domestic sources towards an increased dependence on imported minerals. This was caused in part by one or each of the following: a lack of local supply of particular minerals, domestic source depletion or exhaustion and the relative ease and inexpensiveness of obtaining minerals from comparatively unexploited sources in underdeveloped and some developing countries, notably in the Middle East, South America, Southern Africa, and Australasia. Governments of the industrialised nations, concerned about the reliance of their economies on imported raw minerals examined both the degree of reliability and the extent of mineral resources in the countries and regions supplying the essential minerals. This brought a painful awareness of the vulnerability of industrialised countries as a result of the possible interruption of their mineral imports. In this regard, the United States of America may be quoted as a case in point: a report by a House of Representatives Subcommittee on Mines and Mining (Santini Subcommittee)1 revealed that the United States in 1980 was dependent on foreign sources for more than 50 per cent for 24 of the 32 minerals essential for national survival. The Subcommittee also acknowledged that although the United States may develop its own alternative energy sources, there are in many cases no substitutes for the strategic + minerals imported from foreign sources, from countries which are often unstable at best, hostile at worst. This resulted in various policy responses as well as contingency measures, amongst other, renewed emphasis on the utilisation of domestic mineral resources, an intensified search for substitutes of critical minerals and increased stockpiling programmes. Increased attention was devoted to analyses of the political and economic conditions prevailing in the regions from which strategic and other minerals are exported to the industrialised countries, and the formulation of policy measures vis-a-vis those regions. One region which attracted a considerable degree of attention has been Southern Africa, and in particular South Africa.2 The Santini Subcommittee affirmed that while the bulk of the minerals imported by the United States is supplied by a number of source countries, a host of critical[t] minerals vital to the well-being of that country (and this includes all the Western industrialised countries) originates from Southern Africa, a region, deservedly referred to as the "Persian Gulf of Minerals". Apart from the Republic of South Africa the mineral-rich countries concerned are Angola (diamonds, iron ore, oil), Botswana (diamonds, coal), South West Africa/Namibia (diamonds, uranium), Zambia (copper, cobalt), Zaire (industrial diamonds, copper, cobalt) and Zimbabwe (gold, nickel, chromium, asbestos). The Subcommittee however noted that, with the exception of cobalt, the greatest portion of the reserves of the critical minerals listed, lies within the borders of South Africa. SOUTH AFRICA A RELIABLE PURVEYOR OF MINERALS In view of the continual instability and political risk, along with the nationalisation of mineral industries in third world countries, importing industrialised nations have in recent years become more and more concerned about security of long-term supply, and have in consequence begun to diversify their mineral enquiries to areas where the following conditions prevail: • Long-standing record of consistency of supply; • An economic system of private enterprise; • Political stability; • A well integrated infrastructure, with a maintenance of transportation and development costs at realistic levels, and • Attractive investment opportunities, with security of the return of profits.

Jan 1, 1982

By Wellington Bruno Silva de Jesus, Esaú Gomes Souza, Luiz Gabriel da Silva Nascimento, Jeovan Ramos Nascimento, Deibson Silva da Costa

O estudo desse trabalho foi voltado para a solidificação unidirecional da liga Al-9%Ni usando um dispositivo em que sua câmera interna não permite a existência de gradiente de temperatura para outra direção que não seja o sentido da solidificação. Após o processo de fusão e solidificação foram coletadas amostras de posições aleatórias ao longo do lingote para serem realizados os procedimentos metalográficos, ensaio mecânico e microscopia óptica e de varredura. A macroestrutura se mostrou predominantemente colunar vertical, e a microestrutura se mostrou dendrítica nas regiões mais próximas a extração de calor tendo seu espaçamento cada vez menor, o que influenciou no aumento da dureza. Observa-se também através de análise de microscopia eletrônica de varredura a presença de uma grande quantidade de fibras de Al3Ni, que também contribuíram para o aumento da resistência da liga.

Oct 1, 2019

By C E. J de Ronde

Most of the world's economically significant volcanogenic massive sulphide (VSM) deposits are considered to have formed in submarine arc and backarc settings. While the Kermadec-Tonga arc is an excellent example of an intra-oceanic arc setting, it remains largely unexplored in terms of submarine mineral resources. More than half of this arc (~1400 km of the >2500-km-long feature) lies within the EEZ of New Zealand, where it is defined by at least one sub-aerial and 33 submarine volcanoes. The NZAPLUME (New Zealand American PLUme Mapping Expedition) cruise of March 1999 provided a systematic assessment ofhydrothermal activity on the southernmost 13 submarine volcanoes along the southern Kermadec arc. Using prospecting techniques based on the physical and chemical detection of hydrothermal plumes, we discovered that more than half (7 of 13) of the southern Kermadec volcanoes host one or more active hydrothermal systems at depths ranging between <200 to 1800 m. Chemical results show that the fluids discharged are compositionally diverse among volcanoes and between sites at a single volcano. Plumes over more than half of the volcanoes are gas-rich (He, CO2, H2S) relative to mid-ocean-ridge (MOR) plumes. In addition, most sites are highly enriched in Fe, yielding Fe/Mn values that far exceed those for MORs. One interpretation consistent with these observations is compositional overprinting by addition of magmatic fluids, which are typically highly enriched in gaseous and ionic components. Regardless of the source, it is clear that the ligands (HS-, Cl-) required to efficiently transport base (e.g. Cu, Zn, Pb) and precious (e.g. Au, Ag) metals to the seafloor are abundant in Kermadec arc fluids. We conclude that modem analogs of VMS deposits are likely forming at multiple sites along the Kermadec arc and within the EEZ of New Zealand.

Jan 1, 2000

Roof falls in coal mines typically occur in or around intersections and this has not changed in the last two decades. This research develops an improved scientific understanding of stress distribution and associated failure behavior around 4-way and 3-way coal mine intersections. Three-dimensional numerical analyses were performed to determine factors that influence intersection stability. The analyses used Hoek-Brown failure criterion. Failure zones around 3-way and 4-way intersections were developed. Intersection span and horizontal stress have a major influence on intersection stability. For the 4-way intersection, pillar corners across the intersection fail first and lead to progressive failure of immediate roof and floor layers. The mechanism of failure is similar for the 3-way entry but the shape and extension of failed zones differ. Coal ribs mostly fail due to tensile stress, while roof and floor strata fail due to shear stresses. Rib corners fail due to a combination of shear and tensile stresses. In addition to stress distribution; safety factor contours analysis was performed to assess stability of intersections.

Feb 27, 2013

By B. W. Frazer

In the numbers of the Engineering and Mining Journal of June 27th and July llth, 1874, there appeared some very complete statistics of the working of some anthracite blast-furnaces belonging to a large establishment in this country, followed by calculations of the heat requirements of the furnaces, similar to those which have been made for European furnaces by Mr. I. Lowthian Bell, Prof. Gruner, Prof. Akerman and others. To the author of these valuable papers, Mr. John A. Church, of New York, the thanks of American iron metallurgists are due for this attempt (the first, to my knowledge at least), to attack systematically and scientifically the problem of economy of fuel in our anthracite blast-furnaces, by applying the formulas obtained from European practice and from the experiments of European metallurgists, to the determination of the amounts and the modes of distribution of the heat production and absorption in our furnaces. In order to facilitate a comparison of the results thus obtained for the anthracite furnaces in question with those obtained for the best types of European coke furnaces, I have reduced 60 the same standad of heat units (the product of the ton and the degree Centigrade), and placed side by side, the calculations of the heat requirements of one of the furnaces of the Clarence works, as given by Mr. Bell, of a furnace at Pouzin, on the banks of the Rhone, given by Prof. Gruner, and of the anthracite furnaces for 1869-73, as given by Mr. Church. Table I shows the different conditions of working of the three furnaces, of which Table II gives the respective heat requirements. I have made this latter table in such a manner as to give for each furnace its heat requirements, both according to the views of Mr. Bell and those of Prof. Gruner. Mr. Bell assumes that all the carbonic acid produced by the decomposition of the carbonate of lime of the charge, is reduced to carbonic oxide by contact with solid carbon ; also, that the carbon of t,he pig iron is a portion of that deposited in the ore in the upper part of the furnace, by the dissociation of carbonic oxide. Prof. Gruner, on the other hand, assumes that all the carbonic acid of the carbonates of the charge escapes unreduced, and that the carbon deposited in the upper part. of the furnace, by the dissociation of carbonic oxide, is again converted into carbonic oxide or

Valuable Components Recovery from Lead-Zinc Metallurgical Slag

Sep 13, 2010

By C. R. Summers, J. N. Murphy

In response to the Coal Mine Health and Safety Act of 1969, mandatory noise standards have been developed that specify time-noise limits of mine personnel exposure. Most affected by elevated noise levels is the pneumatic roof bolter operator, both in terms of levels near or in excess of 115 dbA and in terms of length of exposure. Therefore, the principal emphasis of this Bureau of Mines report is on pneumatic drill noise control. It is not the intent of this report to suggest any drill redesign; instead, methods are suggested to reduce the noise level by complementing existing machines. An integral muffler system and a separate muffler system were tested in an attempt to lower pneurnaric drill noise levels. Pneumatic drills, when new, operate at about 115 dbA when drilling in sandstone. Using the drill muffler systems, it was possible to decrease the noise level of a 115 -dbA s rope drill to approximately 100 dbA.

Jan 1, 1974

By T. N. Andersen, K. J. Richards, C. N. Wright

The kinetics of the important reactions occurring in an electrowinning cell have been determined. This information has been used to quantify relationships between the operating variables of current density, solution composition, agitation, and temperature and the resulting current efficiency and deposit quality. Analysis of these results has shown (1) the importance of dissolved iron in determining maximum possible current efficiency and corrosion rate at the cathode suspension loop, (2) the role of agitation, current density, inert salts and temperature in*determining deposit quality and (3) the effects of non-uniformity in the hydrodynamic conditions from the bottom to top of the cell. The significance of the results of this study to the operation of a commercial plant directly treating acid leach solutions is discussed.

Jan 1, 1973

By S. P. Goplen, M. Henriksen, T. F. Barron

In the past decade, numerous large scale drilling projects have made use of reverse circulation air lift methods. Reverse air lift pumping can be established by injecting gas into a column of liquid; the subsequently decreased density of the gas-liquid mixture allows atmospheric pressure outside the lift conduit to establish flow. The rate of flow can be controlled by varying the gas to liquid ratio. A typical reverse circulation air lift system is depicted in [Fig. 1]. Allen 1 has described a number of reverse air lift drilling projects. Although cited examples are generally related to large diameter holes, the method has seen use in other applications such as sand dredging, chemical pumping, water well pumping. and continuous coring. One particular benefit obtained with enclosed reverse circulation drilling is elimination of lost circulation. The required air/water ratio for pumping at a given submergence and lift has been established experimentally by Gibbs.2 His data, however, do not reflect sensitivity of flow rate to air/water ratio. Further, in Gibbs' work, air apparently is injec-

Jan 1, 1980

The brown coal deposits of the Latrobe Valley are ideal for open cut mining and this method has been used since the start of coal winning in 1894. Operations at the main Yall9urn open cut commenced in 1922, but after a few years the main excavators were replaced by German continuous excavators and subsequent developments of Yallourn and the newer Morwell open cut have been based on this type of plant. The reasons for preferring continuous to intermittent excavators in the Latrobe Valley are indicated in this paper.Under the pressure of post-war conditions, and from their long experience and ability, German engineers have recently made substantial improvements in their continuous excavators and these developments have been enhanced by some American innovations. These changes have extended the economic limits of open cut mining and also serve to emphasize the close inter-relation between the nature of coal and overburden deposits, excavator design and methods of operation.As an aid to descriRing recent excavator developments, this interdependence is demonstrated by means of diagrams which show typical methods of operations, together with examples of actual machines using these methods. The types of excavator dealt with are mainly those in use at, or destined for Yallourn or Morwell open cuts, together with additional types used in U.S.A. and Western Europe. For completeness, and also because they will continue in service at Yallourn and Morwell for some years, rail-mounted dredgers have been included in this paper even though in Europe they are now regarded as obsolescent.Explanations are given of how the intrinsic qualities of Latrobe Valley brown coal and overburden have sometimes prevented overseas plants from operating with the full efficiencies and/or in the methods visualized by the manufacturer, and references are made to the modifications and investigations being undertaken to overcome these problems.A compresensive bibliography is given. Dates shown on illustrations are not commissioning dates of the plant concerned, but the year when photographed.

Jan 1, 1960

By Michael Trevits

The NIOSH Lake Lynn Laboratory (LLL) is a unique research facility, located about 50 miles southeast of Pittsburgh, Pennsylvania, that is designed to provide a full-scale mining environment for testing and evaluation of mine health and safety technologies. The LLL occupies more than 400 acres and is composed of surface test and training areas and an underground mine. The Lake Lynn Experimental Mine (LLEM) was built at an abandoned commercial limestone quarry where surface mining ceased in the late 1960's. Later, new underground development was constructed to simulate modern-day coal mining scenarios; including room-and-pillar and longwall mining layouts. In January 1994, a sinkhole opened southeast of the No. 4 Portal of the LLEM and since then, the area of the underground failure and surface deformation has continued to expand and now includes several interconnected sinkholes. A concern developed that the overburden instability could expand and affect the structural integrity of the nearby highwall and the No. 4 Portal. It was unsafe to conduct a detailed underground survey of the mine in this area because the mine roof conditions near the No. 4 Portal had deteriorated significantly. It was decided to investigate the overburden conditions near the No. 4 Portal using ground penetrating radar (GPR). A GPR survey grid was located along an access road that passes over the top of the portal. To delineate the mine conditions near the portal, antennas whose frequency spectra produced pulses centered near 100- and 200-MHz were used. The results of the GPR survey suggests that the overburden rock units appear to be laterally consistent to a depth of about 15-ft. Below that point, the overburden appears to be significantly disturbed and it was hypothesized that this area contains a large roof fall. A follow-up ground truth survey of the mine roof conditions was conducted from the mouth of the portal. It is concluded that the observations and measurements made from the radar records appear to be correct as a large roof fall was observed and measured from the mine portal area.

Jan 1, 2005

By T. Suzuki

LABOR. conditions have finally caused rock-drilling machines to supplant hand drillers in the Japanese mining industry, and have encouraged this study. During a period of three years 25,000 tests were made on 67 different American, Japanese, and European rock drills, using, respectively, the Paynter testing machine, and drilling in granite and limestone. Recorded were: air consumption, speed of rotation, torque of rotation, foot-pounds of striking energy, air pressures, input horsepowers, and speed of rock penetration. The author expresses his views on the interrelation of these factors and offers theoretical support, as well, by formulas based upon the mechanics of impact. He discusses the different designs of the valves, cylinders, piston hammers and rotation devices involved in the different types of rock drills, with respect to their merits and defects and offers conclusions about the factors that should be considered in the new design of a superior rock drill. The author's mathematical demonstrations and arguments for a value of "best feed clearance" of the drill bit from the rock are based upon the hand-operated screw-fed type of hammer drill. Automatic feeds have not been considered in this paper except for the tests on one drifter with air feed, 10 air-feed stopers, and some hand-held blockholers. The following classes of drills, with one of each model, size, or type, were tested: 23 heavy drifters, 34 light drifters and hand-held drills, and 10 stopers. They represented the following makes and models: 40 from the United States—namely, Ingersoll-Rand 18, 148, L-74, 24-70, N-72, N-75, R-72, 26, BAR-33, BCR-430, DCRW-23, RA-12, CA-31, CC-11; Denver 7, 107, WT-21, WT-31, WT-331, WT-337 (models WT with motor rotation, screw feed), 11, Waugh 93, 95; Waugh 16; Sullivan DR-6, DW-64, T-3; DP-321, DP-331; DA-21, DT-44, DT-421; Gilman AX-321 (motor rotation and air feed); Cleveland D-5; AIBQ, 44-SWR,

Jan 1, 1940

By T. Suzuki

LABOR. conditions have finally caused rock-drilling machines to supplant hand drillers in the Japanese mining industry, and have encouraged this study. During a period of three years 25,000 tests were made on 67 different American, Japanese, and European rock drills, using, respectively, the Paynter testing machine, and drilling in granite and limestone. Recorded were: air consumption, speed of rotation, torque of rotation, foot-pounds of striking energy, air pressures, input horsepowers, and speed of rock penetration. The author expresses his views on the interrelation of these factors and offers theoretical support, as well, by formulas based upon the mechanics of impact. He discusses the different designs of the valves, cylinders, piston hammers and rotation devices involved in the different types of rock drills, with respect to their merits and defects and offers conclusions about the factors that should be considered in the new design of a superior rock drill. The author's mathematical demonstrations and arguments for a value of "best feed clearance" of the drill bit from the rock are based upon the hand-operated screw-fed type of hammer drill. Automatic feeds have not been considered in this paper except for the tests on one drifter with air feed, 10 air-feed stopers, and some hand-held blockholers. The following classes of drills, with one of each model, size, or type, were tested: 23 heavy drifters, 34 light drifters and hand-held drills, and 10 stopers. They represented the following makes and models: 40 from the United States—namely, Ingersoll-Rand 18, 148, L-74, 24-70, N-72, N-75, R-72, 26, BAR-33, BCR-430, DCRW-23, RA-12, CA-31, CC-11; Denver 7, 107, WT-21, WT-31, WT-331, WT-337 (models WT with motor rotation, screw feed), 11, Waugh 93, 95; Waugh 16; Sullivan DR-6, DW-64, T-3; DP-321, DP-331; DA-21, DT-44, DT-421; Gilman AX-321 (motor rotation and air feed); Cleveland D-5; AIBQ, 44-SWR,

Jan 1, 1940

By Marius Jacobs

"Safety performance in many companies and even industries has stalled in the few years. Accidents rates are at a "plateau" and yet, serious accidents and fatality rates are not. In more dramatic cases, such as in the BP Texas disaster, organizations that have "exemplary" safety statistics, suddenly have a catastrophic or multi-fatality event occurring. Other classic examples are the Piper Alpha disaster and NASA’s Challenger and Columbia disasters and even the Chernobyl nuclear reactor. Looking into the root causes of these accidents provides an insight into the events and deficiencies that led up to the accident, but what are the common features in the organization’s mindset? What characterizes these organizations’ decision-making, their approach to safety and to risk and are there specific cultural features that can be delineated? The research and review presented in this paper covers a period since 1994, which started in the Australian resource industry and since then covered international events. The features of these organizations are summarized as the seven deadly delusions, based on extensiveresearch since 1997 of organizations that suffered unexpected disasters.The Piper Alpha Oil Rig disaster in the North Sea, on the 6 July 1988, was one of the most pivotal events in safety around the world. It changed the thinking and focus of governments, whole industries and led to numerous books and papers. It resulted in new legislation, textbooks and a critical self-examination by the oil and gas industry.In short, an explosion and fire occurred when a pipe started leaking gas and ignited. A temporary flange, with no safety valve, was used to block off this pipe during a maintenance operation the previous shift. The permit to advise operators not to start the pumps on this line was misplaced and lost. Several deficiencies, problems and system failures coincided. A key factor was that the water deluge system was inoperable at the time and failed to extinguish the large fire that erupted, followed by an even larger gas explosion. The accommodation unit, situated on top of the oil rig, was the main "killing field" - most men gathered here to await instructions (which never came) and where they died from smoke inhalation. Later, a large explosion of the gas pipeline from an adjoined rig exploded and killed more people.The line of events and the associated system failures are all very relevant in the analysis of the accident, and provide the only insight into what caused the accident. But much "further back", inside the organization’s culture, lurks more dark matter. The first inclination is to ask what was "deficient" in the culture. Did they not care enough about safety, or about their people? Did they have a culture where production decisions were more important than safety considerations? Did they ‘coerce’ supervisors and employees to ignore safety precautions or did they just "fly by the seat of their pants"?Not surprisingly, it is very difficult to identify the true nature of the culture in that business because in such an aftermath of death and destruction, no one dare say that the safety culture was a ‘positive one, focused and caring’ or that the company was doing well in safety and that this is only a freak accident. Indeed, there were many deficiencies in the organization’s systems and procedures, such as the permit to work system.But there are some niggling questions: How is then that the Piper Alpha Oil Rig was actually considered the company’s most productive and safest oil rig in the North Sea? Why would this rig win a safety competition, 6 months before the disaster, with the deficient permit as its most outstanding successful system?"

Jan 1, 2014

By Yousef Ghorbani, Abolfazl Danesh, Fatemeh Kazemi, Ataallah Bahrami, Morteza Abdollahi

The abstract highlights the impact of flocculants used in the middle thickener of a copper-molybdenum plant on both process water quality and molybdenite floatability. The study investigates the effect of a starch-based flocculant (wheat starch) on the efficiency of the middle thickener and molybdenite flotation. The findings indicate that the presence of starch influences the settling behavior of particles with different shapes, and the dosage of starch affects both molybdenum recovery and the presence of copper minerals in the molybdenum concentrate.

Mar 7, 2022

By James Goldberg, Mark Withey

The Material Service Thornton quarry is a multi-million annual production tons complex. Surrounded by busy surface highways, and divided by a railroad on the north/south axis and further divided by a major interstate highway on the east/west axis, blasting is a daily challenge. This paper deals with the problems of production blasting in an area adjacent to that interstate highway, and paralleling a busy four-lane highway. Discussion includes primary blasting issues such as borehole size, drill patterns and flyrock controls. Discussion also includes blast designs, timing schematics, smooth-wall blasting solutions, traffic and vibration concerns and many other factors influencing the success of this project.

Jan 1, 2006

Suggestions have been made at various times that there may be a recurrence of lodes similar to those at Kalgoorlie in the country to the south of the Golden Mile, but, so far as is known, there has been no geological evidence to support these suggestions apart from the possible extension of the younger quartz-dolerite greenstone in this direction.Geological mapping carried out by the writer in the Coolgardie district in 1946, provided some additional geological evidence to support this claim, and the ideas then held have since been expanded and are now considered to be sufficiently advanced to present them as concrete suggestions. As will be seen from the following pages, the critical area for lode prospecting is Hannan's Lake, where the basement rocks may include younger quartz dolerite greenstone, which, although perhaps distributed over a smaller area than at Kalgoorlie, could, on structural grounds, have a similar fracture system and similar ore deposition.There is little need to stress the importance discoveries in this area would have in prolonging the life of the field, and stimulating the post-war gold mining revival.Previous Work: Only the publications having a direct bearing on the preparation of this paper are given in the list of selected references, but the writer is very conscious of the fact that much other geological work has been carried out in the Kalgoorlie district since its discovery, by the W.A. Department of Mines, by mining companies, and others, all of which has contributed to the present knowledge of the field, and acknowledgment of the value of this work is given herewith. In presenting the suggestions in this paper a broad structural control of ore deposition is assumed, but this has already been established in other parts of the goldfields of Western Australia, including adjacent areas. In the early nineteen thirties, the Western Mining Corporation commenced work on the basis that there was a close relationship between geological structure and auriferous ore deposition, and a similar approach was first made by the Geological Survey of Western Australia in the South Yilgarn in 1935. These ideas were further developed during later surveys, particularly in the North Yilgarn and the Mount Margaret Goldfield.During the Coolgardie Survey in 1946, broad structural mapping was done in greater detail than before, and the structural ideas were implemented and further developed, leading to some success.Other work to which particular acknowledgment is given is that of Stiltwell, Gustafson and Miller, Forman, Prider and Finucane, at Kalgoorlie, and that of Honman in the Kalgoorlie-Coolgardie district, references to which are given at the end of this paper.Valuable constructive criticism of this paper has been given by Professor E. de C. Clarke and Dr. R. T. Prider, of the University of Western Australia.

Jan 1, 1950

By Trevor Harris, Martin Harris

"This paper evaluates the effect of grind size on the flotation performance of a platinum ore from the UG2 reef of the Bushveld Igneous Complex, in South Africa. The study was conducted on the Mintek Flotation Pilot Plant Facility, located in Johannesburg, and represented a thorough evaluation of the application of the flotation modelling methodology developed jointly by the University of Cape Town and the Julius Kruttschnitt Mineral Research Centre at the University of Queensland through the AMIRA P9 Project. A simulation model of the pilot plant data was successfully implemented, providing a set of circuit modelling parameters that appeared to be both consistent and well correlated to measurable characteristics of the ore and the pilot circuit operating conditions. The findings indicate that the methodology that was used could well provide a useful framework for developing optimisation criteria for industrial flotation circuits in combination with appropriate feed grind size and regrind size targets.INTRODUCTIONIt has long been recognised that the size distribution of an ore is one of the most important factors in the determination of the performance of a flotation process. It therefore follows that the optimisation of a flotation plant cannot be considered without due recognition of the interdependence of this process with the process of comminution. There are numerous qualitative guidelines for the selection of an optimum grind target for a particular operation. Mineralogical analysis can readily provide information on liberation as a function of grind, and the desirable particle size range for optimum mineral flotation is well established in both theory and practice (see for example Trahar, 198 1). For some operations, meeting these two criteria simultaneously is relatively simple. For the majority of operations, such mineralogically “easy” deposits, if they ever existed, have long been exhausted, and the optimum grind represents a highly complex compromise between liberation and overgrinding of both desirable minerals and gangue. This is particularly true for circuits that include regrind stages, where both primary and secondary (and sometime even tertiary) grind targets must be specified. As has been pointed out in a recent paper by Bazin and Hodouin (2001), there is little or no information in the literature to assist plant engineers in the selection of optimum grind targets for complex ore deposits, so current practice is primarily based on rules-of-thumb and experience. This problem is further compounded by the fact that once grind targets have been selected for a particular operation, the assessment and adjustment of these targets based on plant surveys is extremely difficult, time consuming and expensive, and is often not attempted unless the plant significantly underperforms relative to expectation. It is therefore clear that the development of a practical quantitative approach to this problem is a high priority for flotation research and development studies."

Jan 1, 2002