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By Howard Smith

FOR several years this Institute has recorded in its TRANSACTIONS the various discoveries of potash? in America, and the successive stages in the development of an independent domestic potash industry. This paper is intended primarily to continue the record through the year 1935. In retrospect it is not inappropriate to note that public interest aroused in 1910 resulted in the production of some 1090 tons of pure potash in 1915, as a small beginning in the domestic inorganic potash industry, and that the infant industry thus begun reaches its majority this year, following a record production in 1935 of about 600,000 tons of potash salts and exports to no less than 22 foreign countries, including six countries in Europe. This production, with an estimated 200,000 tons of pure potash, may be compared with a production in 1934 of 430,157 tons with an equivalent of 144,342 tons of pure potash.

Jan 1, 1936

By David L. Daniels

The U.S. Geological Survey has for many years been flying and compiling aeromagnetic surveys. The aim is complete coverage of the United States, about half of which is presently done. Colored aeromagnetic maps at a scale of 1:1,000,000 are published as the states are completed; Minnesota and Colorado have been published. Michigan, Iowa, Nevada, Utah, Maryland and Virginia are presently being processed. Some of the most spectacular data collected to date is from the Piedmont of the Eastern United States. I am going to discuss a preliminary aeromagnetic map of the Piedmont region between New York and North Carolina, where coverage is nearly complete. This map has been compiled from many surveys. Flight spacing over Piedmont rocks is 1/4 to 1 mile with flight elevation of 500 feet above ground. The spacing over the Virginia Coastal Plain and Valley and Ridge regions is wider at 2 - 3 miles. Much of the data in Virginia has been produced by the Virginia Division of Mineral Resources. The map is colored on a spectral color scheme with red for the higher intensities and violet the low intensities. Each color represents a 100 gamma interval. Some of the highest intensities are beyond the range of the 13 colors - these are left white. It is necessary, of course, to remove first, the Earth's main magnetic field. The Geological Survey uses the International Geomagnetic Reference Field or IGRF (Fabiano and Peddie, 1969). The use of color in aeromagnetic maps is not new, but then not common. We have found that colored aeromagnetic contour maps are more useful by far than the uncolored versions because they allow the user to instantly compare intensities in widely separated areas and visualize long wavelength anomalies even when numerous short wavelength anomalies' are superimposed. One tends to see only steep gradients on uncolored aeromagnetic maps, the broad anomalies being quite invisible. We feel that colored maps take the place of various mathematically derived maps such as second derivative or averaged maps.

Jan 1, 1973

By Q. Shi

An investigation into the hydrophobic aggregation of ultrafine smithsonite in surfactant solution has been undertaken through a combination of hydrophobic flocculation experiments, zeta potential measurements, surface tension measurements, and contact angle measurements. The experimental results have revealed that the behaviors of hydrophobic aggregation were closely correlated with the particle hydrophobicity, but they were not lowered byte change of the particle surface charges due to surfactants adsorption. On the other hand, the liquid (solution) surface tension (?LV) plays an important role in hydrophobic aggregation, and the hydrophobic aggregation could not occur below the critical liquid (solution) surface tension (?c). Meanwhile, this flocculation has been observed to require sufficient stirring strength and magnitudes of kinetic energy input to achieve the maximum aggregation degree. From the microflotation results, it has been found that the flotation kinetics response of smithsonite fines is markedly improved due to sufficient stirring strength, and the stirring strength influenced the floc flotation in a manner quite similar to their influence on the hydrophobic aggregation, suggesting that the formation of hydrophobic flocs is a promising means to recover smithsonite in the fine size range.

Sep 1, 2012

By Lunarzewski L

Gas problems, largely instantaneous outbursts of coal and gas, arose in the early days of coal mining in Australia, leading to attempts at predrainage often including destressing. With deeper mining and new gassy areas being mined, gas problems have increased. This has led to more research, such as into coal-gas relationships, and more practical trials into seam gas drainage in both the Sydney and Bowen basins. Predrainage techniques have been devised to suit the special Australian geological conditions and to take into account the erratic occurrence of CO, (nearly 100 per cent in some cases) in the seam gas. Better mining methods and other improvements are continuing. The introduction of post-drainage has been simplified by the adaptation of long established overseas techniques and equipment.Utilisation of seam gases in Australia is complicated by the presence of CO, but even with pure CH. little has been done.Seam gas drainage has some disadvantages such as the need for, and the dangers of, complex and rigorously controlled plant. Also drained coal becomes harder and dustier.

Jan 1, 1985

Forty two new apatite and zircon fission track analyses on the Kubor-Marum-Bena Bena area of northern Papua New Guinea severely constrain the timing of tectonic events and hence the tectonic models for New Guinea, particularly arc-continent collision. In addition, the data can be analysed regionally in terms of known and assumed lithospheric fault zones inferred to control mineralisation (eg. Corbett 1994; Kendrick et al 1995; Hill et al 1996) to determine reactivation of these zones. When combined with the new kinematic plate models for the evolution of New Guinea (Hall 1997) there is the potential to predict likely zones of mineralisation. The low-medium grade? Palaeozoic rocks of the Bena Bena terrane yielded a zircon fission track age of 17 Ma, indicating the time of cooling below 200¦C. The age is consistent with `the shift, at about 16-18 Ma, from volcanolithic sediments to mixed provenance sediments rich in quartz and metasedimentary lithic fragments in the southern Finisterre Ranges (Abbott et al. 1994). This shift was recorded in the Sukurum Formation, which ranges in age from Middle Miocene to Pliocene with quartzose and metasedimentary grains in all samples. Although recording rocks at temperatures of 200¦C and hence depths of ---5km, the 17 Ma age suggests the Bena Dena terrane was rapidly cooling at that time due to uplift and erosion, supplying metasediments to the southern flank of the Finisterre Range, currently 100 km to the east. Significantly, the Middle Miocene Akuna Intrusive Complex, dated 14-17 Ma by Page (1976), lies almost entirely within or adjacent to the Bena Bena terrane. Potentially the uplift, erosion and cooling of the terrane at 17 Ma may have been caused by the rising plutons. If so the 800 sq km exposure Akuna Intrusive Complex at the SE end of the Bena Bena terrane may have been the focus of uplift and supplied the metasedimentary detritus to the Finisterre Range. This suggests that the Finisterre Range was not far removed from the Bena Bena terrane, perhaps less than the 200 - 400 km indicated by Abbott et al (1984). The Akuna Intrusive Complex probably resulted from subduction of the Solomon Sea Plate beneath the PNG margin. In order for the subducted slab to reach depths of -100km below the area to facilitate partial melting and plutonism (Hamilton 1994), subduction probably commenced 3-5 Ma Ma before plutonism, ie at or prior to 20 Ma suggesting a significant change in the tectonic regime at -20 Ma, perhaps related to collision of the Solomons - Ontong Java Plateau collision (eg. Hall 1997). The main result to emerge from the 28 apatite fission track analyses is that the whole of the study area underwent rapid cooling due to uplift and denudation in the Late Miocene, mainly between 7-10 Ma. Results from several samples indicate that they were not totally overprinted prior to uplift indicating maximum burial of -3 km in the Middle Miocene, assuming normal temperature gradients. The burial is less if higher gradients are assumed, allowing for Middle Miocene plutonism. The Late Miocene cooling in the Mobile Belt agrees well with the Pliocene to Recent cooling in the Fold Belt to the SW, interpreted to be due to uplift and erosion associated with fold and thrust deformation of the Miocene Limestones (Hill & Gleadow 1989). This timing relationship suggests, that compressional deformation in the Mobile Belt occurred in the Late Miocene, at 105 Ma, and that the deformation migrated towards the undeformed foreland in the southwest in the Pliocene, at 5-2 Ma. The regional Late Miocene uplift and denudation in the Mobile Belt is also consistent with that postulated by Crowhurst et al (1996; 1997) for northwest PNG, although they considered the event to have occurred mainly from 8-5 Ma. If so, then the uplift and denudation may have been migrating from east to west as well as to the south into the Fold Belt. These timing relationships place significant constraints on tectonic models for the area, indicating that the major compressional pulse in PNG commenced in the northeast at -10 Ma and migrated to the southwest and west in the latest Miocene to Pliocene. This suggests that the initial arc-continent collision and associated shortening occurred in the Late Miocene around -10-12 Ma. This immediately followed intrusion and cooling of the Akuna Intrusive Complex at -17-14 Ma and the Bismarck Intrusive Complex at -12.5 Ma (Page 1976), indicating a linkage between the end of plutonism and the start of compressional deformation. The timing is consistent with the observation of Hamilton (1994) that in areas of subduction `the common regime in overriding plates is extensional and leading edges are crumpled only in collisions. This suggests that the Middle Miocene magmatism in northern New Guinea occurred during extension above a subducting slab and was terminated by Late Miocene arc collision and resultant compression commencing at -10-12 Ma. In general, these data indicate that the acme of denudation and cooling in the Mobile Belt was in the Late Miocene, with relatively little denudation there since. In contrast, Hill & Gleadow (1989) found that the peak of denudation in basement outcrops in the Fold Belt was in the Pliocene at -4 Ma. However, in this study some samples from the Mobile Belt yielded Pliocene ages or high

Jan 1, 1997

By C Simpson

The Pilbara region of Western Australia is well known for its abundant exports of hematite-goethite deposits, which have been mined and exported since the 1960s. Magnetite has also been mined in Australia throughout this period, although historically of much lower production volumes (WA Iron Ore profile, 2016). Magnetite offers a source supply of material >66 per cent iron grade product, which is used as premium feed (predominantly pellets) to blast furnaces or specialised steel mills.The Iron Bridge project area contains outcropping magnetite and hematite banded iron formation (BIF), which within the region was recognised as having potential to host economic mineralisation during the 1960s. Development within the project area, however, did not commence until Fortescue Metals Group acquired the tenements based on a 2004 agreement, formed a joint venture with interested groups and then initiated an assessment for magnetite (rather than hematite) mining potential. The combined deposits now have an identified large mineral resource inventory, with test work demonstrating they are able to produce a magnetite concentrate of greater than 66 per cent Fe over an extended mine life. This concentrate would be suitable for forming pellets or feed for direct reduced iron products.The deposits form a singular orebody, approximately 12 km in length by 1 km in width and extending to depths beyond 600 m. The four main deposits are geographically separate and have subtle mineralogical differences, thought driven by the degree of deformation and alteration within each area.Definition of the stratigraphy, structure and key mineralogy of the deposits has been carried out through several stages of exploration and project development. This has also included recent mining and processing of more than 1 Mt of feed material to an on-site processing facility. This demonstrated at a production scale that dry plus wet processing techniques can efficiently separate the magnetite from the gangue minerals to form a suitable (marketable) product.Geometallurgical classification of the host stratigraphy has been carried out from analysing the high volume of quantitative data available for this deposit. This has allowed definition of mappable units within the fresh BIF to be used as a driver in mine scheduling, delivering optimal feed to the processing plant.Construction of mine and processing facilities is expected to commence once all technical risks have been addressed, market conditions are deemed appropriate and approval is given by the joint venture partners.CITATION:Simpson, C, 2017. The Iron Bridge magnetite deposits, in Proceedings Iron Ore 2017, pp 287–294 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

Discounted cash flow (DCF) methods are well suited and recommended as a primary valuation method for mineral assets for which there are at least indicated resources and some form of feasibility study containing engineering, production and capital and operating cost data. DCF methods are also applicable as a secondary or check valuation method for exploration properties for which no technical study has been prepared. For projects where little or no engineering, production and/or cost data is available, the process of formulating a project concept by specialists who do not possess experience and expertise in the relevant technical faculties is totally rejected as a basis for applying DCF techniques as a primary valuation method. Such an approach runs counter to The Australasian Institute of Mining and Metallurgy (AusIMM) requirement to apply relevant expertise to specific aspects of mineral valuation. Technical and commercial inputs to mineral valuation should be reviewed by specialists who have specific expertise in the relevant disciplines, and should be tempered by the quantity and quality of technical evaluation which has been undertaken and the development status of the asset.

Jan 1, 1994

By X. J. Luo, F. Zhang

"Metallurgical slag (MS) such as steel slag, copper slag is a renewable resource and its compressive strength exceeds 200MPa in general. Because pure metal slug can easily be mixed into MS, complex recycle system is necessary in order to realize MS’s recycling. Meanwhile, there is high equipment failure rate in conventional crushing system. New crushing systems with inertial cone crusher could solve this problem very well. Recovery rate of MS tailings requires that crushing product can’t contain too much oversize product, so the essential equipment include two crushers and one sieve in the traditional crushing system. The new crushing system which only includes two crushers can meet the requirement and simplify the crush process. Investment of crushing equipment and infrastructure can be cut down. Operating and maintenance costs can be obviously reduced due to the simple process, which also could achieve high energy saving and excellent economic efficiency.INTRODUCTIONMetallurgical Slag (MS) such as steel slag, copper slag is a typical industrial solid waste and it threatens our environment’s safe. Metallurgical enterprises must take action to settle these wastes in order to protect our environment. Because pure metal slug can easily be mixed into MS, its uniaxial compressive strength (UCS) will exceed 200Mpa. If crushing station employs traditional crushing equipment, equipment failure will be easily caused because of these pure metal slugs. Coarse crushing equipment usually adapts jaw crusher in traditional Crushing technology and rod mill will be utilized to finish the secondary and fine crushing works. And the same time screening machinery should be used to ensure the suitable particle size (Figure 1)."

Jan 1, 2016

By G. T. Higgins

PREVIOUS workers1,2 have found evidence of exaggerated grain growth or secondary recrystallization on annealing sponge zirconium at temperatures high in the a, phase field, but no details of the orientation relationship between the secondary grains and "as-recrystallized" matrix were reported. In other hexagonal metals, namely dilute Mg-A13 and Cd-zn4 alloys, secondary recrystallization has been observed in which the secondary grains are related to the primary recrystallized structure by rotations about the c axis. These rotations are thus comparable with the rotations about the (111) axis observed in the secondary recrystallization of fcc metals. In the current work secondary recrystallization has been observed on annealing iodide zirconium at 800°C and the associated changes in crystallographic texture have been examined. The material employed was arc-melted iodide zirconium of the following composition: Impurity O H Fe Hf Pb I Ni C1 A1 ppm by wt 130 5 230 98 23 28 200 39 30 This was received as 0.25-in. plate, and, prior to the annealing studies, was cold-rolled to 0.040 in. Specimens 1 in. sq were chemically polished and annealed for various times at 800°C in a vacuum better than 5x 10-6 Torr. For metallographic examination specimens were first chemically polished and then anodized8 to enhance contrast between the grains when examined under polarized light. Changes in crystallographic orientation associated with the development of secondary grains were followed by (1011) and (0002) pole-figure determinations using a conventional Schulz goniometer in reflection. Filtered Cr Ka radiation was employed and great care was taken to avoid spurious re- sults due to the close proximity of the Bragg angles for the (1011) and (0002) reflections. Figs. 1 and 2 illustrate the change in grain structure on annealing at 800°C. After 24 hr the structure has ceased to be equiaxed due to the development of certain grains in preference to others. It is notable that the secondary grains do not grow to the extent observed in sponge zirconium.1,2 This appears to be due in part to the fact that normal grain growth is inhibited in the less pure sponge zirconium, with the result that the driving force for secondary recrystallization remains high, while at the same time the number of grains able to develop in the presence of the impurities is also smaller. As a consequence, in sponge zirconium those grains that do develop preferentially are able to grow into the fine -grained matrix without impingement, while in iodide zirconium the preferential growth of many grains leads to early impingement. The pole figures determined for specimens annealed for 5 min and 24 hr at 800°C are illustrated respectively in Figs. 3 and 4. These indicate that the dominant feature of the initial recrystallized texture consists of basal planes at an angle of 321/2 deg to the sheet surface, with a (1120) axis lying parallel to the

Jan 1, 1967

By Charles Catlett

My attention having been called several years ago to the possibility of increasing the yield of coke per ton of coal, as obtained in certain bee-hive ovens, I called the attention of the Institute to the matter at the New York meeting in 1899. I have had occasion since to witness the indifference with which this matter is ordinarily considered, and, on the other hand, the marked improvement which comes from even a most perfunctory effort in that direction; and I am almost tempted to say that nothing in connection with the coking of coal is at present so important. There are other factors, which are fundamental and necessary; but they have been considered already ; while the question of yield is, as a rule, absolutely ignored, or some figure is taken as the result of a special burning of one or two ovens, and the assumption is made that the whole battery is yielding at that rate. The uncertainty of this assumption I may illustrate by saying that, in my own observation, the burning of a single oven in a battery frequently gives, by actual weight, as much as 69 or 70 per cent. of merchantable coke, while the battery as a whole was yielding only an average of 63 per cent. Only from careful records, checked at least once a month, of the weight of the coal going to the ovens and the weight of coke produced, can any correct idea of the actual yield be gained, or methods be modified so as to produce good results; yet, as a rule, the crudest estimates are usually the only available data. In many cases there are reasons for this loose practice. The coal is mined by measurement; the payment for drawing the ovens is in proportion to the amount of cod which goes to them; and, not uncommonly, the royalty is so much a ton of coke, not of coal. The mine-manager is tempted to increase the volume of coal mined which is paid for as a ton, and to do the same thing in charging the ovens. Nor does he

Jan 1, 1903

By J. A. Herbst, K. N. Han, P. B. Queneau, S. W. Asihene

As hydrometallurgy matures as a technology, more of its existing process knowledge will continue to be summarized in the form of detailed mathematical models. This development is happening at a time when major improvements in computer hardware have reduced the cost of computing. The opportunity then exists, through the solution of these process models, to design, control, and optimize hydrometallurgical plants on the basis of the physics and chemistry of its processes and less on empiricism. In this paper, a review of the current capabilities of sensors and phenomenological models for selected hydrometallurgical processes is presented. Future trends, in terms of the control and optimization of hydrometallurgical plants, are then explored. The possibility of simultaneously optimizing plant design and associated process control system performance is discussed.

Jan 1, 1993

By B. W. Cavender

Innovative mining and metallurgical operating techniques and processes can be identified and developed by analyzing changes as they occurs within the mine, plant, technology or industry. Sources of change to be monitored for innovative opportunities include unexpected successes or failures, incongruities between perceived and actual events, process needs, changes in perceptions and the development of new knowledge. Innovation can be organized, practiced and managed. The perception of change as an opportunity rather than a threat is mandatory, as is the systematic measurement of innovative performance. Innovation is enhanced by specifically designed policies regarding organizational structure and staffing, daily management practices and compensation and incentives.

Jan 1, 1996

By John A. Rumball, Martin R. Houchin

"For gold leaching of oxide ores, the optimum cyanide : oxygen ratio is approximately 106 mg/L NaCN : 10 mg/L O2 (6.9:1 by mole). In sulphide ores, galvanic coupling of the gold with the electrically conductive sulphides significantly increases this ratio such that leaching may occur in a relatively low dissolved oxygen (DO) environment.RESULTS AND DISCUSSIONGold leaching in a carbon in pulp (CIP) and carbon in leach (CIL) circuit is driven by the supply of cyanide and oxygen, as described by Elsner’s equation (1):• 4Au + 8CN- + O2 + 2H2O ? 4Au(CN)2 - + 4OH- (1)Equation 1 suggests that the ideal molar cyanide : oxygen ratio should be 8:1, or 122.5 mg/L NaCN to 10 mg/L of DO. It is generally accepted however, that oxygen is not completely reduced to hydroxide at the gold surface, and that equation (2) better represents the gold leaching reaction (Marsden and House, 1992):• 4Au + 8CN- + 2O2 + H2O ? 4Au(CN)2 - + 2OH- + H2O2 (2)Additionally, since gold leaching is limited by either the diffusion of cyanide or oxygen to the gold surface (Habashi, 1993), then the relative diffusion rates of cyanide and oxygen must also be taken into account. Marsden and House (1992) suggest that the ideal molar cyanide : oxygen ratio is 6:1, while a more recent investigation using laboratory and plant observations (Heath and Rumball, 1998) suggested a molar ratio of 6.9:1.In practice, although a cyanide : oxygen mole ratio of 6.9:1 applies to some circuits, there are many instances when this is not the case.In sulphide ores, galvanic coupling of the gold with the electrically conductive sulphides significantly increases this ratio. Galvanically connected sulphides, and possibly carbon, provide a large surface area for oxygen reduction. As the cathode surface area increases, the oxygen concentration required to sustain the same rate of gold oxidation decreases proportionately.Galvanically connected particles may be composite particles, however they may simply be liberated sulphides in the same suspension as the gold. Particle collisions within a slurry are sufficient to provide momentary galvanic connection (Greet, 1995)."

Jan 1, 2003

This paper looks at the problems associated with surface settlements and other subsidence effects from the underground extraction of coal in relation to consent applications under the Resource Management Act. The main features of subsidence are examined with respect to identifying the adverse effects as defined under the RMA. Particular attention is paid to sites where little or no data is available as in the case of greenfield sites or at mines where new or different mining methods are being introduced. In these situations it is not possible to make accurate predictions of settlements or strains and therefore other factors need to be considered. The long term effects which might occur post mining are examined in relation to mitigation and management options.

Jan 1, 2003

By J Ralston, G B. N Kaggwa, L Huynh

Three polymers of varying chemistries and molecular weights have been used to depress talc in a model sulfide ore consisting of talc, pentlandite, and chalcopyrite. Flotation testing revealed a distinct hierarchy of effectiveness of the polymers in the depression of talc (HP Starch > Polymer-H > Dextrin WY) but a different order of effectiveness for depression selectivity (Dextrin WY > Polymer-H > HP Starch). Adsorption isotherm determinations for the gangue and valuable mineral phases indicate that the differences in selectivity are partially due to adsorbed amount variations, with Dextrin WY adsorbing marginally less on the sulfides than Polymer-H. Contact angle measurements on packed particle beds have revealed that the polymers have differing abilities to reduce the contact angle of talc and the sulfide minerals. An explanation of the observed trends is given in terms of the binding mechanisms of the polymers on the talc and the sulfide mineral phases. Order of addition effects between collector and depressant were also investigated using adsorption isotherm determinations for the polymers in the presence of a pre-adsorbed layer of collector and vice versa. Adsorption of the polymers was not affected by the presence of the collector. Similar results were obtained for the adsorption of collector in the presence of pre-adsorbed layers of polymer.

Jan 1, 2005

By Dr. Hans Von Höfer

APART from the hypothesis of a .cosmic origin (which failed of acceptance because it was not adequately supported by facts), the only important controversy concerning the origin of petroleum has been, for a long time, between the advocates of inorganic and of organic origin respectively. Each of these theories has had a long history of development, and is still being perfected, under the influence of two causes: (1) the increasingly extensive and thorough study of the oil-fields (of which new examples are periodically discovered and opened); and (2) the progress of synthetic experiments devoted to this question. Moreover, the advance in our physical and chemical knowledge of the properties of this peculiar natural product has necessarily modified all criticism of conflicting views. I. THE HYPOTHESIS OF INORGANIC ORIGIN That the notion of an inorganic origin of petroleum, first set forth by Berthelot in 1866, and afterward ingeniously developed and formulated by Mendelejeff, should thus have proceeded chiefly from chemists, is quite natural; for the question was one of possible chemical processes in the earth's interior, and of imagined chemical reactions to be, verified by experiment. Hypotheses of this kind were suggested by many chemists, of whom two, P. Sabatier and J. H. Senderens, may be specially named by reason of their highly interesting chemical experiments. Among geologists, Mendelejeff's hypothesis was received at first with much interest and favor; for it rested on the assumption of a central terrestrial mass of iron carbide, and the geologists had good reasons for adopting that assumption. Yet comparatively few of them attempted to furnish geological proofs of the hypothesis: the majority either silently believed in it, or for one or another reason rejected it altogether.

Jan 5, 1914

By Dr. George W. Annadale, Dr. Adrian G. Chantler

Materials which are likely to produce Acid Rock Drainage (ARV) can be identified with a reasonable degree of certainty. However, it is not currently possible to predict the concentrations of future contaminant discharges with similar confidence. One way of overcoming this problem is to model the uncertainty in knowledge related to estimates of future contaminant concentrations, and utilize this information in a decision model to decide on acceptable levels of expenditure on ARV control measures. The paper presents a risk modeling approach and proposes a decision model.

Jan 1, 1992

By R R. Dimock

A goal of all mine operators is to optimize the breakage of the inplace rock to achieve maximum excavating efficiency. The use of the seismograph at Kennecott Copper Corporation's Nevada Mines Division, open pit mine in Ely, Nevada, has demonstrated that optimum blastability can be predicted by knowing the seismic velocity of the inplace rock. The relationship of seismic velocity to the quantity of the explosive required to achieve adequate breakage of the material can be determined. Once quantified, this relationship can be used by the mine operator to obtain the optimum drill pattern and powder factor for breaking the material to be excavated. A substantial savings in primary and secondary drilling and blasting costs can result from using the seismograph for blastability determination.

Jan 1, 1976

By Rafael Padilla

The recovery of copper from chalcopyrite concentrates by leaching is difficult due to the slow dissolution kinetics of this mineral in most leaching media. However, recovery of copper from sulfidized chalcopyrite (a mixture of CuS and FeS2) by leaching is faster and could be selective depending on the leaching media. In this paper, the result of an investigation on the H2SO4-O2 pressure leaching of sulfidized chalcopyrite is presented. The variables considered in the study were stirring speed, concentration of sulfuric acid, temperature, and partial pressure of oxygen. The experimental data indicated that stirring speed over 500 rpm and sulfuric acid concentration over 0.1 M had very little effect on the leaching rate. An increase in temperature from 90 to 100 ºC increased both copper and iron dissolution; however, further increase to 120 ºC affected negatively the copper dissolution. Oxygen partial pressure was found to be the main variable that controls the copper/iron selectivity of the leaching. An increase in oxygen partial pressure increased significantly the rate of copper dissolution but deteriorated the copper/iron selectivity. The analysis for sulfur of the leaching solid residues indicated that most of the copper sulfide sulfur in the sulfidized concentrate oxidized to elemental sulfur.

Jan 1, 2006

By C. L. Workmann Davies

Underground transport and communication in collieries was the theme selected for the 1983 mining school conducted by The South African Institute of Mining and Metallurgy. The response from the industry was so good that three separate schools of one week each were arranged, and a total of 222 delegates attended. Development of Mineral Resources The Institution of Mining and Metallurgy and The Department of Mineral Resources, Government of Thailand, with the cooperation of the Thai Mining Association and Chulalongkorn University, is to hold an international conference entitled 'Role of Government in Mineral Resources Development' in Bangkok from 5th to 8th Decembc -:" 1983. Electronics in Mining A symposium entitled 'Electronics in Mining', organized by The South African Institute of ElectriealEngineers, is to be held in Randburg, South Africa, from 18th to 20th September, 1984.

Jan 1, 1983