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By Pierre de P. Ricketts

Having had occasion while in Europe during the past summer to visit some of the foreign mints and assay offices connected with the same, I thought a brief description of the general process of coining employed, and such items connected with assaying as were new, might prove interesting to the Institute. The principal foreign mints are: the Royal Mint, London; and the mints in Paris, Brussels, Utrecht, Berlin, Vienna, Copenhagen, St. Petersburg, Stockholm, Madrid, Milan, Rome, and Constantinople. My time only permitted my visiting a few of the principal and largest given in the list, and for a description of the remainder I am indebted to the kindness of Mr. James M. Napier, who in company with the deputy master, and chemist of the Royal Mint, made a complete inspection of all the European Mints in 1870.

By G. D. Trump, F. L. Stanley

Spirals have become one of the most popular methods for treating fine coal. Unfortunately, spirals tend to produce an undesirably high specific gravity cut point and often misplace significant amounts of coal and/or rock. In the present study, a process-engineering tool known as linear circuit analysis was used to identify problems with traditional spiral circuits and to suggest alternative configurations. These analyses indicate that a modified rougher-cleaner circuit incorporating a middlings recycle stream offers the best option for improving performance while maintaining a reasonable circulating load. In light of this finding, a full-scale test circuit was installed and evaluated at an existing preparation plant. Data obtained from the plant tests indicate that the new spiral circuit can simultaneously reduce the cut point and improve separation efficiency. Preliminary economic analysis show that the new circuit provides an attractive payback on capital investment.

Jan 1, 1999

By Y Peng, D Liu, S Vink, B Wang

There have been strong industrial observations that clay minerals have a deleterious effect on mineral flotation grade and recovery. However, rigorous explanation on the role of clay minerals in flotation and effective ways to reduce their negative effects are not available. In this study, the flotation behaviour of low quality and high quality coal samples were examined at the Xstrata Oaky Creek Coal plant, and laboratory in fresh and recycled water with high ionic strength. Anionic and non-ionic dispersants including lignosulfonates and triblock copolymers were also tested with an objective of improving coal flotation in recycled water. It was found that overly stable froth was produced in the flotation of both low quality and high quality coal samples in saline water. Speciation modelling indicated precipitation of hydrophilic components which may adversely affect the flotation. Despite the overly stable froth, saline water produced much higher combustible recovery than fresh water without significantly losing the product quality. Lignosulfonate dispersants displayed a potential to improve the flotation in fresh water, but not in saline water. Significant flotation improvement was achieved with the triblock copolymer examined in both fresh and saline water.CITATION:Liu, D, Wang, B, Peng, Y and Vink, S, 2012. Determining the effect of clay minerals on coal flotation using saline water, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 151-158 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

AS I told you before in the treatise on ores, once these are found (whether they are ores of metals or semiminerals) it is necessary to assay them in order to know what is in them, since the judgment of the sight is not sufficient for recognizing the quantity or even what substance they contain. For this reason, it is necessary to come to assaying and, with the knowledge of experience, to weigh their virtues and to proceed with the work or withdraw from it and its expense; and also through knowledge to make provision for their defects if some evilness harms the ores. For if you should have need of a thing that would help them and should not find it, all that you have done would be lost; and, on the other hand, if you should find that the ores are abundant and rich and easy to smelt, you take courage to continue without respect for anything. Therefore, in the following book I shall tell you first in general how the assay of all the metals should be made. I shall enlarge in particular on silver more than on any of the others since it is more important. Then I shall tell you how the ores should be prepared for smelting and also how blast furnaces and other furnaces for smelting such ores should be constructed, and finally how all elemental mixtures of metals are to be separated one from the other with the ability and power of art, and how they are reduced to their final perfection and fineness according to their species.

Jan 1, 1942

By R. J. A. Fricker

IT is the purpose of this essay to give a reasonably complete description of shaft sinking under a rock pentice in a small Northern Ontario gold property. Hallnor is in many ways an exceptional mine, but the sinking operations here described are but typical examples of the excellent practice for which Canadian mines and mining engineers are justly famous the world over. The worth of the subject lies, therefore, nor in its originality, but in its soundness; not in the spectacular, but in the economical and safe. Attention is particularly drawn to the excellent safety record and to the exceptionally low overall sinking cost. INTRODUCTION Prior to April, 1939, the Hallnor No. 1 shaft had been sunk vertically to a depth of 997 feet below the surface. It is a three-compartment shaft, 19 ft. 10 in. by 7ft. 7 in. outside the timbers (see Figure 1).

Jan 1, 1941

By L. D. Mullins, W. R. Bartlett, R. H. Barham, W. L. Wahl

This paper describes an electrical model and its applicution to the analysis of four reservoirs in Saudi Arabia. The model has 2,501 mesh points and represents 35,000 sq miles of the Arab-D member. Details of modeling such as mesh size, control problems and standards of performance in matching reservoir history are discussed. The particular performance match achieved for the Arab-D rnember is presented. Details such as permeability barriers, aquifer depletion and iwerference between oil fields are given. The performance match realized in the Abqaiq pool is presented in detail. INTRODUCTION The resistor-capacitor network and associated control equipment described in this paper comprise an electrical analog of a reservoir system. Similar equipment has been used to study the transient response of reservoirs for many years. The unique feature of the model and application to be described is the extremely large size of the model and reservoir system, and the detail observed in simulating the reservoir with the model. The Arabian American Oil Co. first became interested in analog computers for simulation of oil reservoirs in 1949. Since that time, several models have been developed, each more elaborate and refined so that the reservoir system might be more closely simulated. The current model is the latest in a series designed, built and operated by the Field Research Laboratory of Socony Mobil Oil Co. in collaboration with Aramco. It has been and continues to be used to study the regional performance of the Arab-D member limestone reservoir. The Arab-D member is one of the Middle East's most prolific producing horizons.. THE MODEL The theory of simulating a reservoir system with an electrical system has been presented in the literature.1-5 Therefore, this paper will not discuss the theoretical aspect of the problem except to point out the correspondence between the fluid system and electrical system, as shown in Table 1. In general, the complete model is made up of input devices, output devices, central control and a resistance-capacitance (RC) network. At times, the RC network alone is referred to as the "model". However, it should be evident from the text which meaning is attached to the word "model". A discussion of the equipment follows. THE RESISTANCE-CAPACITANCE NETWORK The RC network consists of 2,501 capacitance decades interconnected through 4,900 resistance decades. The components are arranged to form a rectangular network of 2,501 mesh points in a 41- X 61-mesh array. Imposing the mesh grid system on the continuous reservoir system divides the reservoir into discrete areal segments. These discrete segments may be of various sizes. More precisely, the mesh size need not be uniform throughout the model. The RC network is fabricated in two sections which are connected at the top. An inside view of the "tunnel" formed by the two sections is shown in Fig. 1. The height and width of the tunnel are shown in the figure. Numerals appear along the bottom and along the back opening of the tunnel. These numbers denote the x and y co-ordinate positions of mesh points. Fig. 2 presents a rear view of one-half the model. The length dimensions of the model, as well as a rear view of the capacitor decades, are shown in this figure. The control dials used in adjusting the resistance and capacitance values on the model can be seen in the enlarged portion of the model shown in Fig. 3. The electrical capacity at any mesh point can range from 0 to 1.0 microfarads set to the nearest tenth of a microfarad. The electric resistance connecting any two mesh points can range from 0 to 9,990,000 ohms set to the nearest 1,000 ohms. External capacitors may be added to any or all mesh points if the need arises. The values of electrical resistance and capacitance are adjusted manually by manipulating the two types of decade units. INPUT EQUIPMENT A considerable quantity of equipment is used to control the input to the RC network. These input devices are

By R. S. Rickard, H. D. Peterson, J. D. Miller, M. C. Fuerstenan

Pure chrysocolla is floated with chelating agents that form insoluble complexes with copper at ambient temperature. Complete flotation is obtained with potassium octyl hydroxamate as collector at pH 6. Flotation response is enhanced with increased temperature when low additions of hydroxamate are involved. A natural ore was floated with 0.4 1b per ton octyl hydroxamate at pH 6.5 and 58°C, and a flotation recovery of 76% was obtained with a concentrate grade of 31.6% copper. The flotation characteristics of the oxide copper minerals, malachite, azurite, and cuprite, have not presented the difficulty for concentration as have those of the copper silicate, chrysocolla. The copper carbonates and oxides respond reasonably well to flotation with conventional collectors, whereas chrysocolla will not respond to flotation with fatty acids or xanthates under normal flotation conditions. In this view then, other reagents will have to be devised to function as collectors for chrysocolla. The most obvious general class of reagents for this purpose would seem to be the organic copper chelating compounds. The utility of chelating agents as collectors in flotation systems has already been demonstrated. For example Vivian1 has floated cassiterite using ammonium nitrosophenylhydroxylamine. Holman2 studied the flotation of nickel oxide ores with dimethylglyoxime and also suggested the use of taurine on oxidized lead ores. A rather detailed study on the application of certain chelating agents to some flotation systems was presented by Gutzeit.3 This work indicated that the formation of surface insoluble chelates is probably responsible for flotation in many cases. The role that soluble chelating agents assume was also presented, that is with effective removal of polyvalent cations by complex formation, effective depression of quartz can be obtained. DeWitt and Batchelder4,5 have shown that oximes function well as collectors for chalcocite, malachite, azurite, and cuprite. Ludt and DeWitt6 have presented the possibility of using dyes, such as octyl malachite green, as a collector for chrysocolla. These works presented by DeWitt et al suggest that organic copper chelating compounds offer considerable promise for concentrating chrysocolla, but that the most suitable chelating reagent from the standpoint of cost and flotation response has yet to be determined. The present investigation was undertaken to study the flotation response of chrysocolla to selected copper chelating compounds, that is ethylenediamine, hexamethylenetetramine, potassium octyl hydroxamate, dimethylglyoxime, and benzoin a-oxime. EXPERIMENTAL MATERIALS Chrysocolla: The chrysocolla used in the microflo-tation studies was from New Mexico and analyzed 20.8% copper. X-ray diffraction showed this material to be amorphous in character, but some faint lines of quartz were noted. A natural oxide copper ore from Utah was also used in the investigation. This ore contains malachite principally but also contains chrysocolla and tenorite together with some sulfide copper. The sulfide copper comprises from 15 to 20% of the total copper content of the ore. Water: Conductivity water was used in the microflo-tation experiments, while Golden tap water was used in the experiments with the natural ore. Reagents: Reagent grade n-amyl alcohol was used as frother in the experiments with pure mineral, while MIBC was used in the work with the ore. Ethylenediamine, hexamethylenetetramine, dimethylglyoxime and benzoin a-oxime were reagent grade in quality. Pure potassium octyl hydroxamate was prepared as follows: 1) 1.0 mole of KOH in 140 cc of methanol was combined with 0.6 mole of hydroxyl-amine hydrochloride in 240 cc of methanol at 40°C (KC1 precipitates under these conditions and to effect complete removal of KCl, the system was cooled to 10°C and filtered), 2) a light methanol wash was then given the KC1 cake, 3) the filtrate was agitated at room temperature and 0.33 mole of the methyl ester of the organic acid (i.e. methyl octanoate) was

Jan 1, 1965

By H. C. Miller

The gas-lift method of flowing oil from wells is the outstanding feature of petroleum technology today. Its forerunner, the air-lift, was used successfully first, in the Baku fields of Russia, in 1899, and later in the Gulf Coast fields of Texas and Louisiana and the Kern River field of California. It is still used to a limited extent in certain oil fields. The use of compressed natural gas for lifting oil from wells has supplanted the air-lift method in a measure in those fields where a sufficient quantity of gas accompanies the oil to make the gas-lift possible, or where natural gas is plentiful and inexpensive. We find, therefore, in California, that natural gas is used at practically every well where a gaseous medium is employed to flow the oil. The use of natural gas has many advantages over that of air. It is possible to recover and save the gasoline from the gas that accompanies the oil to the surface. This gasoline would be wasted if air were used as the lifting medium. Also, certain proportions of air and gas form an explosive mixture that cannot be handled safely by compressors. Another advantage that gas has over air is that gas under pressure is more soluble in oil. Gas in solution in oil reduces the viscosity of the oil that is being produced and causes it to flow more readily through the tubing and flow lines. The gas-lift has made it possible to recover many thousands of barrels of oil from deep wells in California that could not have been produced otherwise. It would not have been economical, had it been mechanically possible, to produce such wells as the world's deepest producing oil well (Miley Athen's No. 6, Rosecrans field, California) by any other method of pumping known today. At this well, production is obtained from between 7305 and 7591 ft. and 11 months after completion of the well, production was being maintained on the gas-lift at approximately 2000 bbl. a month. The crookedness of the hole, or its diameter and depth will not prevent the successful application of gas-lift pumping when other conditions are favorable.

Jan 1, 1928

The economic significance of a fundamental understanding of the mineral pyrrhotite is dis- cussed. Particular emphasis is placed on the relationship of other sulphide minerals to the pyrrhotite when it is the major sulphide mineral present in an ore body. Studies of the Kambalda nickel deposit are used to give a better under- standing of (a) the genesis and other character- istics of a particular ore body (b) the textural relationships between pyrrhotite and other sul- phide minerals (c) magnetic properties of natural pyrrhotite, and (e) the oxidation and supergene processes that take place in a sulphide ore body.

Jan 1, 1972

The precious metallogenic belt and its geoloqical-tectonic location in eastern China.The precious metallogenic belt of eastern China is located in the western part of the Pacific gold metallogenic belt, and occurs in the upper levels of the continent cut by a deep fault structure tending NNE and NE, and active during the Mesozoic. The precious metallogenic period ranges mainly from Late Jurassic to Early Cretaceous (160 Ma-110 Ma); subordinate mineralisation occurred during the Hercynian period, and was rare in the proterozoic.Seven precious metallogenic belts are recognised from east to west, i.e. from continent to the margin active belts, as follows:1. Au-Ag-Te metallogenic belt of East Shandong Province2. Au-Ag-Pb-Zn metallogenic belt of west Liaoning-Miyun area3. Au-Os-Ir-Cr-Cu Mo metallogenic belt of Chengde Pingquan area4. Au-Ag-Pb-Zn metallogenic belt of Zhang Xuan area5. Au-Ag-Pb-Zn metallogenic belt of Zhejiang province6. Au-Ag-Se metallogenic belt of East Qinling area7. Au-Pd-Cu-Mo metallogenic belt of Wansu area

Jan 1, 1990

By Radoslav Despotovic

The developed radiometric method of particle system analysis has been applied to investigate the bulk properties of particles precipitated from solutions. The nature and principles of the method applied are described briefly, and some possible models in the field of fine colloid particles precipitation discussed. Changes in radionuclide distribution were followed during the solid phase formation and the data were used to calculate changes in bulk composition of colloid precipitates. The radiometric data show interesting phenomena closely connected with the characteristic of bulk particles. The measured radiometric data are highly reproducible, the applied methods have proved to be sensitive, and the developed techniques have been tested by various standard procedures.

Jan 1, 1980

By Paul T. Allsman

The guiding principle in developing this plan resulted from evaluating potential future markets for oil, the quantity of mineable oil shale and the optimum rate of production comensurate with market demand on the available oil from shale. In addition, the rate of production may depend upon a solution to the problems of scarcity of resources other than oil shale. The rate of production finally will tend to establish the choice of technologies with these limits. The principle components discussed will be: 1) The place of oil shale among the various energy sources and its relative adaptability for use in the area of major consumptive demand. 2) A recalculation of the reserves and their classification on the basis of quantity, grade - gallons per ton, - and physical characteristics principally thickness, overburden and depth.

Jan 1, 1982

By Erik Richer La Fleche

LEGAL RISKS LEGAL RISKS ARE COUNTRY RATHER THAN PROJECT RISKS OTHER COUNTRY RISKS ARE POLITICAL AND MACRO-ECONOMIC RISKS COUNTRY RISKS ARE EXAMINED AFTER PROJECT RISKS COUNTRY RISKS COUNTRY RISKS INCLUDE: WAR AND ARMED CONFLICT TERRORISM AND SABOTAGE CURRENCY INCONVERTIBILTY AND TRANSFER NATIONALIZATION AND CREEPING EXPROPRIATION GOVERNMENTAL BREACH AND REPUDIATION OF CONTRACT CHANGE OF GOVERNMENT CORRUPTION COUNTRY RISKS FIRST NATIONS AND LANDOWNER CLAIMS LABOUR UNREST SINGLE CAUSE ACTIVISTS REGULATORY AND BUREAUCRATIC DELAYS CONFLICT BETWEEN GOVERNMENT LEVELS ETHIC AND RELIGIOUS TENSIONS INTERNATIONAL SANCTIONS TAXATION CHANGES CHANGES IN LAW

May 1, 2013

By McOnie A. W, Rutherford PG

A volcanic sequence is described from the Golden Cross Mine, Waihi, New Zealand. The sequence includes seven lithostratigraphic units comprising flow and pyroclastic units of Coromandel Group andesite and dacite and overlying Whitianga Group dacite and rhyolite which is intruded by the Golden Cross dacite porphyry and rhyolite dykes. The sequence is mineralized and is unconformably overlain bv_ two post-mineral units, the lacustnne Waitekauri beds and Omahine Subgroup andesite. Detailed structural analysis of mine data has identified four deformational events (D 1-D4) and related these to the gold-silver mineralizing events. Faulting was coeval with the mineralization and directly controlled the development, localization, style and geometry of the ore shoots. Mineralization developed in competent lithologies where dilation occurred during faulting. The Empire Fault is the master shear which controlled fluid flow. Mineralized veining developed in response to tectonic pulses occurring at slightly different stages as represented by the underground Empire vein complex and the open pit vein array. The mineralizing events culminated with the deposition of barren calcite veins. Post-mineral movement along the Western Boundary fault appears to have offset the ore body.

Jan 1, 1995

Subsidence data resulting from longwall mining in the northern part of the Newcastle Coalfield of New South Wales has been reviewed. Themain factors influencing subsidence variability in this area (apart from width/height ratio) are strong bridging strata, the effects of the first major goaf fall, mining direction and depth of cover. In 1987 the NSW Department of Mineral Resources produced a guide to subsidence prediction for the Newcastle Coalfield which is still widely used. The current study shows this guide to be no longer appropriate for this area. An alternative prediction curve, incorporating more recent data, is suggested.

Jan 1, 1998

By Orion Ciftja, Arjan Ciftja

"The directional solidification method is routinely used to produce polycrystalline silicon, an important material for the photovoltaic (PV) industry. The form of the solid-liquid interface during solidification has considerable influence on the material quality. The dissolved impurities and the solid inclusions above the solidification front affect the interface and may cause interface breakdown. We investigate the effects of pushing and engulfment of silicon carbide (SiC) particles by the solidification front during directional solidification of silicon. We employ a 12kg directional-crystallization furnace to cast the molten silicon. We use upgraded metallurgical grade silicon with low concentrations of metallic impurities (< 5ppm) and a high content of carbon (700 ppm) present as SiC particles. Samples from the cast polycrystalline silicon ingots are investigated by light microscope. The expected interaction of impurities with the solidification front is investigated theoretically using empirical models. The data obtained from the models are in good agreement with the experimental results.IntroductionDirectional solidification is a well-known method for producing multi-crystalline silicon for the PV industry. In this method a planar front, achieved during solidification, results in a clearly defined interface between the solid and the liquid phase. The solubility of major impurities is higher in the liquid than in the solid phase. Therefore, directional solidification will work as a purification process where the impurities are retained in the liquid phase [1]. Apart from the process of removing the dissolved elements in molten silicon, the directional solidification plays also another role. It will interact with the solid particles that may be present in the melt. When a liquid containing an insoluble particle is solidified, three distinct interaction phenomena are observed: engulfment of particles, continuous pushing, and entrapment [2]. The term “engulfment” is used to describe incorporation of a particle by a planar interface, and the term “entrapment” is used for particle incorporation by a cellular or dendritic interface (see Figure 1) [3]."

Jan 1, 2014

By Fathi Habashi

Precipitation of a metal from an aqueous solution of its salts by another metal is known as cementation, because the precipitated metal is usually cemented on the added metal. This phenomena was once described by the alchemists as "transmutation," when they dipped a piece of iron in a solution of copper sulfate and the iron was coated with a layer of metallic copper. The process can be predicted in terms of electrode potentials. The metal with the more positive (oxidation) potential, as given in Table 13-1 of the electromotive series, will pass into solution and displace a metal with a less positive potential.

Jan 1, 1970

By Edward L. Burwell

The Bureau of Mines investigated the use of dilute polymer in brine solutions to increase the efficiency of air in gas flooding model oil reservoirs. Slugs (0.23 pore volume) of 500 ppm polyacrylamide were injected into a model, consisting of a high- and a low-permeability core, that had been previously gas flooded to residual oil. Gas flooding was then resumed. Of the total gas volume injected, the percentage entering the high-permeability zone was greatly reduced after polymer injection but remained unchanged when slugs of water without polymer were used.

Jan 1, 1970

By B. Q. Li, S. P. Song

"Numerical models are developed to represent complex electromagnetic, free surface deformation and fluid flow phenomena in floating zone refining processes with radio frequency inductive heating. The computational methodology is based on the coupled finite/boundary element method for the electromagnetic field distribution and the Galerkin finite element method for magnetically driven fluid flow and free surface profiles of the molten zone. With the models, the complex transport and free surface phenomena in a floating zone system can be studied as a function of various operating conditions including applied current, frequency, inductor position and shape, surface tension, floating zone diameter and height. Results show that the equilibrium shape is sensitive to the height of the molten zone and that the free surface shapes can have a significant effect on the melt flow in the molten zone. Our extensive simulations also suggest that to ensure accurate results, the same mesh should be used, whenever possible, for both the electromagnetic forces and fluid flow calculations.1. IntroductionThe floating zone processes have been widely used in the materials industry to grow ultra-pure rare earth metal or semiconductor single crystals for sensor or electronic applications that have a tough demand on purity. Developed based on the principle of magnetic melting/levitation, the processes possess a main advantage that the molten zone is supported in air by the electromagnetic forces generated by the coil (see Figure 1), and therefore is free from contamination from a container. Consequently, the final products made from the floating zone processes have higher inherent purity than those by other techniques [1-4].Complex physical phenomena occur in the floating zone processing of materials. These include free surface deformation, magnetically-driven melt flow, which may be turbulent or mildly turbulent [5] depending on the applied conditions, and solidification. Thermal stresses also develop in the single crystals, which are affected by the flow and temperature field and which can have direct implications to qualities of single crystals [6]. An understanding of the fundamentals governing these physical phenomena can be of critical value in elucidating the physics that controls the properties of the metal or semiconductor crystals being produced, thereby providing a rational basis for process improvement and quality control."

Jan 1, 1997

By N. M. Steven, J. M. Moore, J. L. Kuyper

Abstract - Mineral exploration and research has led to the identification of four types of tungsten mineralization in the NE-trending, largely ensialic, inland branch of the late Proterozoic/early Paleozoic Pan-African Damara Orogen. The mineralization (mainly scheelite) occurs in a terrane (the Central Zone) that is characterized by multiple deformation, greenschist/amphibolite-facies metamorphism and numerous peraluminous S-type granitic and pegmatitic intrusions. The four major types of scheelite mineralization are (in ascending stratigraphie order of host rock): (1) thin (5 cm to 2 meter) quartz+ plagioclase+ diopside ± scapolite cale-silicate granofels with finely disseminated scheelite (scheelite-bearing granofels; SBG) developed as discontinuous intercalations within the cale-silicate rocks of the Khan, Spes Bona, Oberwasser and Kuiseb Formations (Nosib and Swakop Groups); garnet+ pyroxene ± vesuvianite + scheelite ± fluorite replacement skarns hosted by Okawayo, Karibib and lower Kuiseb Formation marbles in the aureoles of late tectonic, unmineralized leucogranites; metaturbidite-hosted scheelite- (and possibly wolfrarnite-) bearing tourmalinites, both stratiform and crosscutting, in the Kuiseb Formation located in the &apos;cleavage fronts&apos; of late tectonic granitoids; scheelite-bearing vesuvianite +quartz+ garnet skarnoid rocks (several hundred meters in length) in the calcareous metaturbidites of the upper Kuiseb Formation. These scheelite occurrences were discovered by the follow-up of a large number of tungsten anomalies located during a regional stream sediment sampling program. Detailed mapping, ultra-violet surveys and rock sampling proved to be the most effective surface exploration techniques for locating mineralization; soil sampling and geophysics were of almost no use. The largest, continuous scheelite-bearing skarn of economic interest, Otjua, has a drill-indicated reserve of 250 000 tonnes at 0.53 wt% W03 and 8 wt% CaF2.

Jan 1, 1994