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By D. A. J. Ross-Watt

Right now the South African mining industry is a high-profile, vital contributor to the nation just as it has been for the past one hundred and twenty-six years since the discovery of diamonds-perhaps even further back if the mining of copper, iron ore, tin, and other minerals in earlier centuries is included. The media in 1995, as has been the case over the years, bear testimony to the complex interactions between the industry and its stakeholders: shareholders, government, employees and their unions, training and educational institutions, researchers, markets, the public, and suppliers of goods, services, and infrastructure. The pressures and challenges that the industry continues to face can be summarized as safety and health, competitiveness, and social and environmental responsibility. There are no surprises here. The motivation for the industry to perform well in these areas is clear; the focus I intend to bring is on the most important tool required for success-that of good mining engineering. This Address sets out - to review the mining aspects that have been discussed in South Africa during the first five years of the decade, a discussion that shows the return of the country as an important mining forum, confirms the role of professional institutes and associations in the development of mining engineering, and brings current relevant issues into focus - to highlight the vital role of mining engineering in the industry, and to identify priorities for the remainder of the decade - to provide the prospective mining engineer, the mining-engineering student and trainee, and the practising mining engineer and mine manager with a better appreciation of the mining-engineering discipline. institutes and ssociations

Jan 1, 1995

A survey has been undertaken of the petrography of North Island greywackes with a particular focus on the occurrence in them of smectite (swelling clay) and chlorite, two minerals that are closely associated, chemically similar, and commonly interlayered with each other. Smectite is the mineral which is a major cause of greywacke aggregatesÆ poor performance. Smectite occurs in post-metamorphic shear zones and in surface weathering profiles over greywackes. This study focuses on the petrography of fresh greywacke rocks.   The occurrence and abundance of smectite and chlorite and their relationship in greywackes is largely a function of the chemistry of the sediment and the maximum temperature that the sediment has been subjected to during diagenesis and/or very low grade (anchizone) metamorphism. Rock chemistry, particularly total iron and MgO, determines the smectite and/or chlorite content in fine-grained greywackes (argillites and siltstones) but chemistry is less influential in sandstones, where at low grades of metamorphism much of the Fe and Mg of the rock is held in unreacted detrital minerals and the mineral constituents of lithic grains.   Four zones which represent different levels of diagenesis and very low grade metamorphism, based on the crystallinity of illite and chlorite in the greywackes, and the proportion of smectite interlayered with chlorite, have been mapped in the North Island. In the anchizone smectite does not appear as a discrete mineral, it is always interlayered with chlorite. In the upper anchizone chlorite contains approximately ten per cent of smectite interlayered with chlorite. In the lower anchizone about 30 per cent smectite can occur in chlorite.   In addition to the smectite and chlorite inherent in the greywackes as the result of the thermal overprint, smectite as a discrete mineral and smectite-chlorite interlayered minerals with high levels of smectite, occur in abundance on shear zone surfaces and in alteration zones adjacent to shear zones; these are the main contributers to the high levels of smectite recorded in many greywacke aggregates.

Jan 1, 2006

By G. P. Dvoichenkova, E. A. Trofimova, M. V. Zaskevich, V. A. Chanturiya

The paper presents theoretical and practical aspects of directed adjustment of physicochemical properties (pH,Eh) and ion composition of recycle and mine water by electrochemical treatment. Treatment is run in the conditioners of diaphragm-type with production of alkaline catholyte of pH value up to 12 and acidic anolyte of pH up to 2. In process of water electrolysis the directed motion of Mg2+ and Ca2+ ions is observed from anode volume to cathode one, were they precipitate as hydroxides and carbonates; it leads to decrease of salt content in anolyte and catholyte. The anolyte has been concentrating anions, it is being saturated with oxygen, which reaches 20-35 mg/L. The results of experimental and industrial testing of electrochemical technique for mine and recycle water in flotation of diamond-containing and sulphide-scheelite, hematite, phosporite, apatite-nephelite, bauxite ores indicated the increase of recovery up to 2-1 5% and grade up to 0,5-2%, concurrent with decrease of reagent consumption from 15 to 50 %. Modules of industrial conditioners of different type capacity have been developed.

Jan 1, 1995

By F. C. Schrader, Alfred H. Brooks

Last fall (1899) we had the good fortune to be able to spend a few weeks in the new placer gold-mining region of Alaska, which is known as the Nome region. Cape Nome, after which the region has been named, and which forms the southeastern corner of the Nome Mining District, is an unimportant promontory on the southern coast of the Seward Peninsula (see map, Fig. 1). The name Seward has recently been given to the great peninsula which forms the northwestern extremity of Alaska. To the north of it is the Arctic ocean, to the south Bering sea, while its wesbernmost extremity, Cape Prince of Wales, is separated from the Asiatic coast by the Bering straits. The coast line of the peninsula is of a cuspate character, consisting of a succession of sandy, crescent-shaped beaches and rocky headlands. The interior has been but little explored; but we know that it is comparatively rugged, the higher mountain peaks rising probably from 4000 to 5000 feet in elevation. The mountains have an easterly and westerly trend, and the water-shed between the two oceans probably nearly bisects the peninsula. At Golofnin bay, the southeastern part of the Seward peninsula, some spruce is found, but to the west the region is entirely timberless, except for a sparse growth of stunted

Jan 1, 1901

By N. S. Stoloff, K. R. Jordan

The temperatwe and grain size dependence of the mechanical avoperties of ordered and disordered Fe-49 pct Co-2 Pct V were investigated. The yield and flow stresses obeyed the Hall-Petch relationship u = ai + kd-&apos;I2. Ohdering reduced the intercept stress cjj and raised the Petch slope, k, at all temperatures. Ordering also increased the temperatwe dependence of k. The ductile to brittle transition temperature increased with order and grair~ size. Cleavage fracture was nucleation limited and the fracture stress did not zlary linearly with d-&apos;". A quantitative test of the Cottrell-Petch fracture theory (and recent modifications which consider the influence of slip mode), demonstvated that this theory is not applicable to FeCo-V. COTTRELL&apos; and etch&apos; independently suggested that a criterion for cleavage failure at the yield point, a,, based on dislocation pileups at a grain boundary or other obstacle to dislocat.ion motion, is: aYYkd&apos;I2 1 opy [ll or, equivalently, aikz,d112 +k:)bpy [2] where a, and ky are the Hall-Petch intercept and slope, respectively, 2d is the grain diameter, P is a geometric factor dependent on the macroscopic ratio between shear and tensile stress, p is the shear modulus, and y is the true elastic surface energy. When the product of quantities on the left side of the equation is equal to or exceeds that on the right, cracks should be able to nucleate and propagate at the yield stress, as shown schematically in Fig. 1. Therefore a high intercept stress, high Petch slope, or coarse grain size favors brittleness. petch3 associated the existence of a ductile to brittle transition in ferrous alloys with the temperature dependence of ai. One of the earliest modifications of the Cottrell-Petch theory was presented by ~rmstrong,~ who derived an expression for transition temperature in terms of several measurable flow and fracture parameters. The latter paper was able to rationalize situations in which the transition temperature increases with decl-easing grain size, as in the case of molybdenum,&apos; and also suggested that Ppy should be a function of grain size as well as temperature. More recently Johnston et a1.6 and Smith and worthington7 have suggested that the temperature or composition dependence ol&apos; ky must also be taken into account if there is any cha.nge in deformation mode, as from wavy to planar slip, or wavy slip to twinning, with change in temperature or solute content. Armstrong %as suggested that for hcp metals changes in o;k,dw> o;k,d1/2< / is / ^^^^ / / y_______________________________________ d-"2 Fig. l—Schematic representation of grain size dependence of yield stress, cry, and fracture stress, CTF. Intersection defined by Cottrell-Petch equation. slip mode should be incorporated in the theory through changes in the critical resolved shear stress for the slip system which controls ky. The purpose of the present investigation was to critically test the modified677 Cottrell-Petch theory of fracture in the superlattice alloy Fe-49 pct Co-2 pct V, by studying the grain size dependence of the yield and fracture stresses over a range of temperatures, in conjunction with an investigation of slip mode and fracture behavior. Previous work has shown that long range order results in a sharp decrease in flow stress, a small increase in work hardening rate and a drastic upward shift in the ductile-brittle transition temperature of F~CO-V.~&apos;~ The only comprehensive study of slip character in this alloy has been reported in a preliminary account of the present investigation.10 EXPERIMENTAL PROCEDURE The experimental work was carried out on material produced from a 10 lb vacuum melted ingot, of composition 49.32 wt pct Co, 2.09 wt pct V, balance Fe. 30-mil thick sheet samples with a 1; in. gage section were machined from cold rolled stock. The degree of cold work ranged from 85 pct for the finest grained samples to 5 pct for the coarsest grain size. Details of ingot fabrication are reported elsewhere." Equi-axed grain sizes in the range 12.7 to 75.4 p were obtained by annealing for varying times at 850°C. (Re-crystallization annealing time, rather than temperature , was varied to control grain size to insure that samples of all grain sizes contained equivalent quenched-in vacancy and interstitial concentrations.) Grain sizes were measured by the line intercept method on several specimens of each grain size. Following recrystallization, all samples were disordered by quenching into iced brine.

Jan 1, 1970

Gold mineralisation at the Macraes Gold Project is hosted in the Hyde-Macraes shear zone and can be traced for ~30km along strike, although economic resources are confined to a 7 km section in the vicinity of the Macraes township. The shear zone, which typically dips at a low angle (~20 o ) to the NE, is bounded by an upper hanging wall shear and a lower footwall fault. Mineralisation occurs along the hangingwall of the shear zone as well as in low angle concordant shears and stockworks. Ore types include graphitic cataclasites with variable amounts of quartz veining, ælode schistsÆ and quartz-vein stockworks. Rehabilitation at the mine has focused on creating an environmentally benign site dominated by pasture to allow continuation of the traditional pre-mine farming economy. Changing regional economics, continued urbanisation and a reduction in traditional employment opportunities has seen a rethink in the long-term rehabilitation outcomes. The community has recognised that the rehabilitated site will provide the basis of a viable tourism venture and the creation of a Heritage and Art Park (working title æGolden Point ParkÆ) is the culmination of that process.

Jan 1, 2002

By John J. Mancini

Elastomeric liner products have been used for over two decades in a wide variety of uses including pond liners, hazardous waste barriers, dam face rehabilitation and mining applications. Asphalt blended with polymers is enjoying renewed interest in the engineering community because of its durability, high yield attributes, fewer CQA steps due to seamless installation, and ease of installation and repair. As in other lining technologies, advancements in polymer chemistry and improvements in installation techniques have had dramatic impact on the quality of fluid-applied asphalt (FAA) membranes. Membrane 6, man­ufactured by Deery Oil, Inc. for over 16 years is a hot-applied polymer modified asphalt membrane that can be applied to a variety of substrates in a reinforced configuration or installed directly on an asphalt surface. By blending thermoplastic polymers with asphalt, very favorable stress/strain characteristics can be achieved (Chambers, 1980). Typically the membrane will yield under rel­atively low stress and also exhibit high elongation capability. In service applications where puncture resistance is a concern, fluid applied asphalt materials have the flexibility and com­pressive strength under heavy loading that leach pad designers may find attractive. Additional security is achieved if long term service life is important as in the case of radioactive waste con­tainment. The Department of Energy selected Membrane 6 over seamed liners for a surface barrier that must isolate and contain radioactive waste for 1000 years. Asphalt has a long history of use as a water-stop material and it is believed that this natural construction material combined with SBS polymers will per-form for a millennium. (Freeman, 1994) The process of installing Membrane 6 varies according to job size and the type of surface to be protected. Lining applica­tions on compacted substrates require the membrane to be applied to a scrim cloth (fig 1). Some early pioneers in FAA technology neglected this step and therefore never achieved per­formance levels that satisfied regulatory guidelines. The scrim provides a cohesive surface that promotes membrane flow while achieving high impermeability (2Xl0 '11).

Jan 1, 1996

In the period considered all coal produced was used locally, and the totals in Table 43 are estimated from the few data available. [ ]

Jan 1, 1942

By Arthur V. Abbott

TO rightly use materials, two kinds of knowledge are essential: first, the actual strength of the substance; and secondly, the forces to which, in the structure, it may be subjected. Nearly all of the data which we have at the present time have been obtained from the experiments made on the materials used in Europe, and by foreign investigators. The materials commonly used in this country, es-

Jan 1, 1884

By L. Ianniello

AMONG the more interesting peculiarities of plutonium is the brittleness of its room-temperature monoclinic phase, a, since the adjacent higher-temperature phase (transformation temperature, 112C), ß, is also monoclinic but very ductile. Other elements, e.g., tin and manganese, have phases which exhibit similar contrast in plasticity. However, it was considered unusual when the a phase which has less than 0.1 pet tensile elongation&apos; was rolled to 90 pct reduction in thickness at room temperature.&apos; Since brittle behavior often is a structure-sensitive property, but could also be the result of covalent-type bonding, further experiments reported here have been conducted in an attempt to illuminate the problem. Electrorefined plutonium was rolled under various conditions and examined to determine the strain-hardening characteristics and also to determine under what conditions rolling could be performed. The rolling mill had 6.0-in.-diam heatable rolls with a variable roll speed (6.25 to 445 in. per min). Microhardness measurements were taken using a square-base diamond indenter with loads from 50 to 1000 g. The method used for rolling plutonium at room temperature consisted of prior

Jan 1, 1964

By Leendert de Witte

A review is given of the principles on which recently proposed methods of electric log interpretation in shaly sands are based and of the evidence brought up in support of the theoretical derivations. It is. pointed out that the qualitative techniques suggested to date have a tendency to be too pessimistic in the prediction of the presence of commercial hydrocarbon accumulations. In the quantitative treatment, a new concept is introduced, namely that of strongly reduced activity of the double layer counter ions which are present near the negatively charged rock surfaces. This lemmu when applied to the calculation of the equilibrium concentratiotls of interstitial waters yields a set of very simple relations. The resulting expressions for electrochemical potentials across rock samples appear in satisfactory agreement with laboratory experiments. The formulae obtained for the electrical conductivity of shaly formatioris are of the same form as those arrived at empirirally by previous workers. Combination of the expres.riorls for potentia1s and conductivities gives a direct proof of the Tixier relation which states that for shaly water sands the product of apparent formation water resistivity and apparent formation factor equals the resistivity of the sand 100 per cent .saturated with formalion water and which was verified by the work of Wyllie and Perkins and their co-workers. The relations for the resistivities and spontaneous porer11inI.s have been extended to the case of hydrocarbon hearing shaly formations, thus laying a formal basis for the quantitative interpretation of electric logs in shaly oil sands. INTRODUCTION The presence of disseminated clays in porous rocks saturated with electrolytic solutions has a strong influence on the transference of ions taking place under electrical or chemical potential gradients. Both the electrochemical emf&apos;s in evidence on the SP curves of electric logs and the electrical conductivity measured on resistivity logs arc directly dependent on the ionic transference in the interstitial waters of the formations traversed by boreholes. A large number of researches have been carried out on the nature and magnitude of the effects of clays on ionic transference. The most recent of these have been described in papers by McCardell and Winsauer,1 2 Wyllie and Southwick,3 poupon, Loy, and Tixier,4 and by Perkins et al.5 Most of these authors consider the effects of the clays as due to the fixed negative charges on the clay lattice. These charges cause the formation of diffuse surface layers with a high concentration of positive ions. The internal solution of the shaly reservoir rock has therefore a different ionic composition and concentration than the electrolyte with which it is in equilibrium (connate water produced from the formation or mud filtrate by which the formation is invaded). To calculate the equilibrium concentration of the internal solution, use is made of the Donnan6 relation, which states that the mean ionic activities of the internal solution and of the external electrolyte must be equal. From this and the

Jan 1, 1956

By Ruben Alvarado

The need to increase business competitiveness while complying with environmental requirements represent the great challenge that the Caletones smelter has decided to face in a new development project with a compromising and willing alliance with its workers. To date, the project is at the feasibility stage, with start up scheduled for the middle of the year 2002. The processing capacity of the Teniente Converters will be increased to levels up to 2400 tpd of chalcopyrite-based concentrates containing 30% Cu, by means of more intensive use of oxygen and improved stabilization of the overall operation. Productivity increses in the converting of white metal and the pyrometallurgical treatment of slag are also planned. As a result of related strategies, the productivity of the supporting facilities, included the capacitiy of the sulfuric acid plants, will be increased. An intensive and well-designed labor-upgrading scheme will allow the transformation of every worker into an expert in his working areas, thus becoming an active driving force in technology development. Mechanization, appropiate infrastructure, and complete process control and instrumentation will give to the skilled and motivated personnel the necessary tools in order to attain the highest potential ever reached with the Teniente technology. The necessary investment for this project based on the adding facilities to the existing plant is only a third of that required to reach the same objective for a greenfield plant, thus yielding a very high return on investment.

Jan 1, 1999

By Arthur V. Abbott

During the past four years I have had occasion to make quite extensive use of steel castings in the manufacture of testing-machines and large scales for Messrs. Fairbanks & Co. The failure of some of these&apos; castings at stresses much below those which were claimed for them by the makers, induced me to institute a series of experiments to determine the actual constructive value of the steel castings now to be obtained in this country. The art of steel-casting is rapidly improving, almost every issue of the scientific press bringing accounts of some new development; consequently, the results of the following experiments are only exponents of the value of steel castings as at present made. In order to make the examination as thorough as possible, ten sets of patterns were made and forwarded to as many different firms in the country who advertised to make steel castings. The first part of the accompanying table gives a list of these manufactures, together with the price per pound. The order accompanying the patterns simply requested the manufacturer to supply two castings from each pattern of his ordinary product of steel. These castings were sent to me and paid for in the usual manner, so that it is probable that the samples fairly represent the quality of the average of steel castings, and are free from the suspicion of being "special runs." Two patterns were sent to each maker, one being a straight

Jan 1, 1886

By David Rahal, Saul Ortiz, Maria Escobedo

The general trend in the minerals industry is towards the processing of fine grained, disseminated mineral deposits. This has led to an increase in the number of fine/ultra-fine grinding installations using stirred media mills. The challenge is that both the equipment type and the mineralogy of the deposit have an effect on specific energy consumption. Fresnillo PLC recognized this issue and addressed it by providing samples for testing in a laboratory regrind system. The objective of the test program was to determine the specific energy required to achieve a product size of 10 µm (P80). A specific energy plot was generated for both a lead and zinc flotation concentrate. It indicated that 34 kWh/t and 51 kWh/t were required for the two samples (Pb and Zn respectively). This difference highlights the effect of mineralogy on the energy required for fine grinding. The regrind feed and products were submitted to a range of basic mineralogy tests to quantify the mineral differences that could have changed the specific energy requirements. These tests provided general mineralogy, documented optical textures, and provided particle size microscopy. The lead concentrate was found to contain significant amounts of silicates in addition to the dominant sulphide, pyrite. The zinc concentrate was determined to be mostly sphalerite with minor amounts of quartz, chalcopyrite, pyrite and galena. The material testing results illustrate the importance of basic mineralogy studies in conjunction with comminution testing to determine specific energy consumption.

Jan 1, 2016

By E. G. Woodruff

Few authors of treatises and papers on engineering subjects hare given adequate attention to topographic maps. The statement applies especially to mining engineering in all branches. Even those who have discussed such maps have treated the subject only in a general way. Therefore it is proposed to outline in this paper a few of the uncommon yet important relationships which topographic maps and their by-product, structure-contour maps, have to modern methods of mining investigation and development when the facts depicted on such maps are properly interpreted. Topography, as suggested by the etymology of the word, means a detailed description of particular places. Written descriptions have been found less effective than the pictorial representations, therefore attempts have been made in various ways to picture the surface features of places. Lines and shading have been used, hachures drawn, and, finally, the contour topographic map. To a large extent this style of map is the result of the demands of engineers. It is designed to meet their needs far more than those of the man untrained in engineering. In fact,. the average man obtains a better idea of the topography of an area from the hachure system than from contour maps. Since the maps have been made chiefly for the use of the engineer, they ought to meet his demands on the one hand, and, on the other, should be used by him to the fullest extent. Such maps, when properly made, accurately portray a portion of the earth&apos;s surface and should present the topography better than a personal examination of the area without a map could present it, because the person making such examination views only a limited portion of the surface at a time, and estimates distances only roughly with his eye. Let the engineer consider carefully the fact that in many instances the topographic map is superior to a personal examination of the surface features of a property because the map is based on careful instrumental measurements, whereas the eye gives imperfect data because it can be used merely for the estimation and

Jan 1, 1914

By Albert Sauveur

Some writers believe that when austenite transforms completely into pearlite on slow cooling through the thermal critical range, such transformation does not imply the formation of any of the so-called transition constituents: martensite, troostite and sorbite. Might it not be claimed with as much justification that when water freezes it does so suddenly, solid ice being obtained without passing through the intermediate stages of ice and water? Obviously, regardless of the speed of solidification, this would be erroneous. Before reaching the completed solid condition, this must of necessity pass through an unbroken series of stages when the system consists of mixtures of water and of ice, the former decreasing and the latter increasing in amount. Are not these "transitionV stages in the freezing of water similar to the transition stages occurring in the transformation of austenite into pearlite? To clarify, let us consider in Fig. 1 the mechanism of the transformation of eutectoid steel from its austenitic to its pearlitic condition as it cools slowly through its thermal critical range. It is generally admitted that this transformation is the result of two distinct phenomena: (1) the allotropic change of gamma iron into alpha iron and (2) the crystallizing out of solution of the carbide Fe3C. Whether this crystallizing of Fe3C implies also its formation is immaterial for our purpose. In other words, whether it is the carbon in atomic dispersion which is present in gamma iron or molecules of Fe3C has no bearing upon the matter to be discussed. The transformation of gamma iron into alpha iron cannot take place suddenly. It must of necessity be progressive, regardless of the speed with which it may take place. At A, for instance, there would be present AB gamma iron and BC alpha iron. The distance MN does not refer to falling temperature, but to the passage of time. It may be assumed that the transformation takes place at a constant temperature (the Ar321 point). In a similar way, the crystallization of Fe3C out of the austenite solid solution must be progressive as depicted between M and N. At A there would be present AB gamma iron, BC alpha iron, CD carbon dissolved in gamma and in alpha iron and DE Fe3C. This condition may be described according to individual preference as martensite or troostite. To sum up, can the metal pass from condition

Jan 1, 1931

The high-shear colloidal mixer is generally recognised as the most efficient method of mixing cement based grouts. Only recently however has this technology been applied to the production of cemented rockfill (CRF) for use in underground mines in North America. Traditionally, paddle type mixers have been used to produce the cement based slurries required for the preparation of CRF. While considerable success has been achieved with these mixers, tremendous advantages are attained with the colloidal mixer. The combined effect of the highly efficient mixing action and the ability to mix low water/solids ratios, allows for reductions in the cement content for a given strength requirement. Cement can also be replaced by cheaper fillers such as flyash, resulting in further cost savings. Although large-scale dedicated CRF batching plants are typical, there is a growing need for mobile plants capable of operating anywhere underground. The compact size and rapid batching speed of high-shear colloidal mixers has allowed them to be incorporated into skid mounted systems capable of producing and discharging cement based slurries onto rockfill aggregate for the production of CRF. In many cases run-of-mine development waste can be used as CRF aggregate with these slurry plants thereby reducing the cost of waste rock removal. These relatively low cost portable plants have now allowed several mines to economically recover isolated pillars and realise positive returns on their investment.

Jan 1, 1998

G. SHERBURNE ROGERS,* Washington, D. C. (written discussion?).- We are indebted to Captain Lucas for an interesting contribution to the literature of the salt-dome oil fields, and especially for his suggestion that a more aggressive method -of prospecting be adopted. The occasional discovery of new fields on, the Gulf Coast is in itself sufficient to show that the oil possibilities of the region are by no means exhausted, and those who have studied the area most thoroughly are the most optimistic regarding its future. Nevertheless, the search for new fields, according to present methods, involves the expenditure of great sums of money annually, for the proportion of dry holes to producing wells drilled yearly in the Gulf Coast region is much&apos; greater than in most areas, even if all the wells drilled in what is commonly regarded as proved territory are included. Not only are the present methods of locating new domes very uncertain, but when a dome is discovered there is no assurance that it will be oil-bearing; or, if so, whether the oil occurs in the cap-rock, in the sands above it, or in some small isolated lens of sand far down on the flanks of the salt mass. As Captain Lucas points out, about all we positively know is that the domes are there and that some of them are oil-bearing; their origin is a matter of controversy and the original source of the oil is conjectural. Under these conditions, it is not surprising that the search for oil is conducted more or less blindly and that dry holes are common. Many wells are drilled each year in an endeavor to find oil at depths of 2000 or 3000 ft. (609 to 914 m.) or less, in locations which most geologists would condemn without hesitation. As Captain Lucas suggests, the money spent in this way might be used to far better advantage in, drilling one deep well in a carefully selected locality. Opinions may differ as to whether such a, well would find oil, and many geologists will probably believe that the chances are against it, yet all will agree that the boring, whether it finds oil or not, will probably throw light on the origin of the domes and on the source and mode of accumulation of the oil, and will therefore be of great interest, not only to the scientist, but to the oil operator.

Jan 10, 1918

By Thomas G. Murdock

ALTHOUGH the contribution of Algeria, including the Sahara, to the local economy and to world mineral supply was small for many years, the spectacular development of an important petroleum and natural-gas industry has changed the position of the country. In 1963 there were decreases in output of most mineral commodities, however oil and gas production forged ahead and established new records. The impact of adverse market conditions and especially the competition from lower cost producing areas was felt by both the metals and nonmetals industries. This and the general economic conditions related to the recovery of the country following the years of strife attending its emergence as an independent state combined to hold back production and development commensurate with resources. The principal events of the year were in the petroleum sector and included the first commercial production from several new fields, some new discoveries, the virtual completion of the first petroleum refinery in the country, and installation of additional pipelines. Progress was made toward the further utilization of the vast resources of natural gas and the provision of additional transportation and refining facilities. In the mining domain the government took over two iron-mining operations, and progress was made towards expanding production of phosphate rock and determining methods of upgrading the Tindouf Iron ores. Completion of the iron and steel plant near Bone was further delayed. The only coal mine reportedly closed down in late 1963.

Jan 1, 1964

Porgera is located in the Central Highlands of Papua New Guinea. Porgera Joint Venture treats a high grade epithennal gold deposit. Most of the gold occurs as submicroscopic particles in a sulphide matrix although there is some quite coarse free gold. Anticipated gold production is 900 000 oz per year for the first six years of operation.Stage I of the treatment plant consisted of a concentrator and leach/CIP Circuit. It was commissioned in August 1990. Design throughput was 1500 tpd with an anticipated gold recovery of 60 per cent. Throughput achieved was actually 1850 tpd with an average gold recovery of 69 per cent. CIP tails were accumulated in a pond awaiting retreatment by pressure oxidation.

Jan 1, 1992