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By Walshe JL, Solomon M

The Emperor vein system lies on the eastern margin of the Tavua volcanic structure. This is of Miocene age and occurs in basalts(the Mba Volcanics) probably underlain at about 2 km by calcite-rich sediments (the Vatukoro Formation). The lodes are generally flatmakes, or steep fault fillings, or complex shatter zones, and consist of quartz and altered wall rock. In areas of open cavities it is possible to establish a paragenesis which involves five quartz stages and two ore mineral stages. The first ore stage contains calaverite, krennerite, sylvanite and native tellurium, the second petzite, hessite and native gold. The quartz stages are thought to have formed slowly (102 years) from boiling solutions of low salinity at temperatures varying with time from about 250¦C to 190¦C. The system was sealed, the temperature gradient near vertical and the mass flux small. The ore mineral stages probably formed relatively rapidly (101years) from boiling solutions at 250¦ to 200¦C when the system was mainly open. Gold deposition was probably largely a result of fall in aH2S due to boiling, the calculated solution concentration falling from a maximum of about 8 ppb at 250¦C to about 8.10-3ppb at 200¦C. Boiling is also probably responsible for an increase in a02 (by loss of H2) and fall in aTe2 (by loss of H2Te). The fluids are thought to have had a large component of meteoric water and to have been heated by plutons in the core of the volcanic structure. Stable isotope data indicate that they derived their carbon from the underlying Vatukoro Formation and their sulphur from sediments. Circulation may have been confined to the outside of the volcanic structure because of the relatively low permeability of the flows, pyroclastics and dykes within it.

Jan 1, 1987

By A. Eilers

COMPOSITION OF CHARGES AND CONSUMPTION OF FUEL AT VARIOUS WORKS. A MARKED peculiarity of most of the smelting-works of the Far West is the looseness with which accounts of the operations are kept. Indeed, probably over half of the works do not keep any detailed accounts at all, the yearly gross statement of profit or loss being considered sufficient for all purposes. The reasons for this must apparently be sought in the as yet unsettled state of all business relations, and in the deplorable fact that only in isolated cases educated metallurgists are in charge of the smelting-works. Continual and regular assays of the ores, by-products, and slags, are almost unknown, so that it is impracticable to ascertain, even approximately, the losses in the smelting processes. Of cases where regular accounts are kept of the quantities of ore smelted, of the composition of charges, and of the fuel consumed, I know only two or three. Under these circumstances it is extremely difficult to collect figures which cover the operations for a considerable length of time, and which are so valuable for the metallurgist, who wishes to get an insight into the economy of smelting operations, as shown by practice. Figures obtained by personal observation, which can of course cover only the brief space of the visit of the travelling metallurgist, must, therefore, be made to replace the more valuable data. The writer has had occasion, during the last and the preceding summer, to visit the larger number of the Western lead-smelting works, and offers, in the following pages, such data relating to the economy of lead-smelting in the blast furnace at various works, as he has been able to obtain. The only object in doing so is to place these figures on record, so that they may be from time to time supplemented with other data, which are now wanting. I. EUREKA CONSOLIDATED COMPANY'S SMELTING-WORKS. These works smelt the ores from the mines of the same company on Ruby Hill, Eureka, Nevada. The supply is almost unlimited,

Jan 1, 1873

By R. Abela

In over ninety per cent of mineral sand plants, the most commonly used equipment is the spiral concentrator. The tonnage treated over typical spiral plants can range from as low as 200 ton per hour up to 6 000 tons per hour. Due to the limited capacity of each spiral, plants consist of multiple spirals assembled into banks. The mixture of minerals present in the sand feed requires several spiral stages to achieve the desired mineral recovery. Due to the complexity of the spiral circuits, there are always some design and operating problems that present themselves in plants. These range from slurry distribution, spirals operating at incorrect design parameters and feed variations. The material being treated is difficult to maintain in suspension due to its high density, resulting in segregation and preferential flow in pipelines, distributors and sumps. The objective of this paper is to highlight common problems associated with spiral installations to designers and operators of plants. Practical solutions are recommended in order to prevent and minimize these mistakes in the design. These solutions may be used to improve performance on operating plants.

Jan 1, 2003

By Liang Sha

In this study, adsorption of copper by chemically modified orange peel was investigated. A conspicuous change occurs in the surface morphology of the biomass due to modification, which is depicted by SEM images. Equilibrium isotherms and kinetics were obtained and the effects of various factors, including solution pH, contact time, initial metal ions concentration and temperature, were studied by batch experiments. Kinetics was found to be best-fit pseudosecond- order equations. Equilibrium was better described by Langermuir isotherms rather than Freudlich isotherms. At 25?, pH5.30, the maximum adsorption capacity was 70.67mg?g-1 . With increase of temperature, adsorption efficiency decreased. The biosorbent was suitable for repeated use for more than five cycles.

Jan 1, 2009

By H. A. Schlesinger

Various studies have estimated that for the next few decades, about half of all new power plants will be nuclear. The other half will be fueled with coal. Pending legislation on air pollution control would require all new coal-fueled power plants to install stack gas scrubbers or other technology to reduce sulfur oxide (SO,) emissions. These regulations would require flue gas desulfurization (FGD) or other technology for SO, reduction even on lower sulfur western coals. Among the options for FGD are single or dual alkali throw away processes using lime or limestone as the major reagent. These processes are currently more economically attractive than recovery processes, such as magnesium oxide and Wellman- Lord, that produce a salable product such as sulfur or sulfuric acid. One of the major problem areas with the throw away processes is disposal of the thrown away solid wastes, primarily calcium sulfite (CaSO3) and calcium sulfate (CaS04). Coal ash also must be disposed of, even if SOx reduction is not required. This paper addresses the alternatives for handling and disposal of throw away lime, limestone, and dual alkali process solid wastes. Advantages, disadvantages, and the economics of various methods are discussed. Both large central station power plants (500-1000 MW capacity) and smaller industrial power plants (up to 100 MW capacity) are considered. High sulfur eastern coals (53% S) and lower sulfur (3 1% S) western coals are considered.

Jan 1, 1981

Petroleum exploration is proceed ing in Western Australia at an ever- increasing pace. Results in recent years have been very successful, with the discovery and development of the Barrow Island oilfield and the Dongara gasfield, and the discovery of several major gas-condensate fields on the Northwest Shelf. The Northwest Shelf discoveries will have a big impact on the economy of the State by providing an abundant indigenous source of energy. Prospects for further large dis- coveries are believed to be excellent. The most prospective areas are thought to be on the continental shelf in the Carnarvon, Browse, Perth, Canning, and Bonaparte Gulf Basins.

Jan 1, 1973

By R. Bauer

Adaptations and redesign of the existing already very successful and proven road milling machine concept and technical innovations such as an optimized, specifically for mining application developed cutting drum, cutting housing design and cutting tools, high manoeuvrability achieved via a tight turning radius, a three disk clutch system and a cutting drum drive that allows for the acceptance of higher loads, a complete reinforcement of the chassis to withstand higher vibrations and torque, the installation of increased engine power via a modern drive unit, a specifically for mining/construction applications developed operator’s platform and finally a redesigned air intake system and the adaptation of the levelling system resulted in far more cost effective and advantageous capabilities of Wirtgen Surface Miner in soft to medium hard mining and construction applications. As the achieved results show for the first time in modern surface mining history mechanized cutting is capable to compete successfully against traditional drill, blast/ripping and other conventional mining methods.

Jan 1, 2007

By J. Handin

Triaxial compression tests with independently applied external confining pressures and internal pore pressures show that the ultimate compressive strengths of representative oil well cements are nearly linear functions of effective pressure — the difference between external and internal pressures on the jacketed cylindrical specimens (to 15,000 psi). The strengths are little affected by the test temperature to 350F (not to be confused with the curing temperature). At an effective pressure of 15,000 psi, strengths are in the rage of 30,000 to 50,000 psi, comparable to those of sedimentary rocks under similar conditions. The cements become very ductile even under low effective pressures; permanent shortenings of 30 per cent or more are attainable without rupture. INTRODUCTION Since the pioneering work of Richart, Brandtzaeg and Brown1 on the failure of cement under combined compressive stresses, it has been recognized that ultimate compressive strength is greatly enhanced by the application of confining pressure. More recently, Mc Henry2 showed that the strength of concrete was a linear function of the effective pressure (the difference between the external confining pressure on a jacketed specimen and the internal fluid pore pressure), at least for a range of 0 to 1,500 psi. The effect of temperature had not been investigated, and no previous systematic triaxial compression testing of naterials used for oilwell cementing seems to have been done. The present work was suggested by the late J. hi. Bugbee3 who stated that "consideration of the common application of high-pressure hydraulic fracturing to the initial completion or recompletion of wells, and the large pressure drawdowns in some producing wells, particularly those in abnormally high-pressure gas-condensate reservoirs, raises the question of what is a suitable cement strength for various completions. The intuitive belief exists that cement strength need be no greater than formation strength. Tests should, however, be conducted at downhole conditions." The ultimate compressive strengths of rocks penetrated by the borehole must rise several fold with increasing depth.4 This marked enhancement of strength is due to the influence of the effective pressure, the total weight per unit area of the overburden less the hydrostatic pore pressure. (The effect of temperature due to the geothermal gradients is relatively small for depths to 30,000 ft.) .A significant comparison of the strengths of rocks and cements at downhole conditions requires knowledge of the confined compressive strengths of cements as well. EXPERIMENTAL PROCEDURES The theory and technique of triaxial compression testing are fully discussed in earlier reports.4-6 Briefly, cylindrical specimens 1-in. long and 0.5-in. in diameter are jacketed in thin copper tubes of negligible strength, placed in the test chamber and subjected to an external confining pressure of kerosene and loaded axially by the piston at a strain rate of 1 per cent per minute. Pore pressures of water (or kerosene) are applied independently through the hollow piston and are maintained constant during the shortening of the specimen, Tests at sensibly 0 pore pressure are arranged so that any free water in the cement can escape to the atmosphere. (If egress of water were denied, pore pressure would rapidly attain the value of the external confining pressure because of reduction of pore space.) The test chamber can be heated for high-temperature experiments. Unless otherwise noted, the cement samples were air dried for about a week. Recorded during a test are pore and confining pressures, shortening and axial differential force (total force less the product of the confining pressure and the area of the piston). True stress-strain curves are constructed by dividing the measured differential force by the actual cross-sectional area of the specimen at a given

Jan 1, 1966

By Graeme Heyes, Warren J. Bruckard, Michael A. Somerville

"Over the past few years CSIRO Minerals has been conducting research aimed at developing a continuous copper converting process to replace the traditional two-stage batch process that is currently used to produce blister copper. Sirosmelt type reactors and calcium-ferrite (lime-based) slags have been used rather than the conventional iron silicate slags. The research work has now been extended to focus on the development of a single-stage continuous copper making process (so-called direct copper converting) in which copper concentrates are converted to low-sulfur blister copper in a single step, that is the smelting and converting steps occur in one continuous stage.One feature of the direct copper converting process is that copper losses to the slag phase can be high, meaning the slag produced needs to be treated to recover the copper value. The feasibility of the whole copper making process will most likely depend on the efficiency and cost effectiveness of the copper recovery stage. Flotation has been identified as the most economical option to recover the copper from direct copper converting slags where it has been estimated that a copper recovery from the slag of above 90% is required to make the overall single stage copper making process economically feasible.A limited series of laboratory batch flotation tests was conducted on a suite of calcium-ferrite-based slags made in laboratory smelting trials. Copper sulfide concentrates from MIM were used as feed-stocks. The objectives of this work were to develop a robust flotation process to maximise the copper recovery and iron rejection from slags made in the process, and to establish operating conditions for future continuous flotation pilot plant trials.The slags treated included a reduced low copper slag, an oxidised high copper slag composite, and a very reduced low copper self-pulverising slag. The copper content of the slags varied from 2.9% to 14% Cu and the CaO/Fe ratio varied between 0.30 and 0.54. In general, the higher the copper content the more oxidised the slag. The copper was present as metallic copper, oxide copper and copper-calcium ferrite phases with the phase mix related to smelting conditions. The slags were crushed, ground, wet-screened at 355 or 210 µm to remove coarse metallic particles of copper, and floated at natural pH (about pH 11) using reagents and conditions appropriate for the selective recovery of the copper phases. Reagent additions were typically 200 g/t KEX and 500 g/t Na2S.9H2O and the grind size was generally a P80 of about 40 µm."

Jan 1, 2003

By Cathy Aimone-Martin, Caitlin Woznick, Brent Meins

This study is a continuation of previous work in which the responses of tall structures to close-in construction blasting at two rock excavation sites are evaluated. A total of eight buildings were instrumented to calculate blast-induced wall strains. Of these structures, five high-rise buildings measuring 166 ft (51 m) to 294 ft (90 m) in height (15 to 24 stories), were included for this study and compared with the results of previous studies that included one to three story residential structures and mid-rise structures (four to six stories). All five structures were built between 1908 and 1940 with interior walls comprising aged plaster. Three of the structures are designated Landmark, subject to a 0.5 in/s (12.7 mm/s) regulated peak particle velocity (PPV) limit. The regulated PPV limit for the two other structures was 2.0 in/s (50.8 mm/s). To date, a total of 450 close-in construction blasts have taken place over six months at the two adjacent projects, blasting three to six times per day at each site. Seismograph instrumentation included tri-axial geophones in the ground and bi-axial geophones (horizontal components only) mounted on structure exteriors at the corners closest to blasting. Peak global wall tensile strains were calculated from time-correlated differential structure displacements in two horizontal directions as measured by upper and lower geophones mounted near the roof and at street levels. Wall strains were correlated with ground excitations to establish a stiffness factor for each structure defined as the upper bound linear regression slope for strain as a function of ground displacement. In addition, a structure-specific regression best-fit function was established to relate horizontal components of displacement to velocity. These two functions were used to determine the maximum ground motion velocity for a desired limit placed on wall strain. A 25 ?-strain limit was suggested for both projects to protect interior plaster walls. To date, global wall strains have not exceeded 0.53 ?-strains (or 47 times the project limit) for peak particle velocities up to 3.49 in/s (88.6 mm/s). This demonstrates the low strain response of tall structures to ground velocities well above regulated limits. The stiffness factor computed for the most flexible high-rise building was 688 in-1 (17475 mm-1). In comparison, stiffness factors for the most flexible residential and mid-rise structures previously studied were 8651 in-1 (219735 mm-1) and 4387 in-1 (111430 mm-1), respectively. Based on a large number of measurements made at these study structures, the maximum horizontal ground velocity needed to achieve 25 ?-strains in walls ranged from 36 in/s (914 mm/s) to 192 in/s (4877 mm/s) because of the high stiffness of these buildings. Such high amplitudes of ground vibrations can never be safely achieved during close-in blasting in urban environments. These excessive values stand to show how unfounded the current limits of 0.5 in/s (12.7 mm/s) and 2.0 in/s (50.8 mm/s) are when applied to massive, tall structures. This study demonstrated that upper structure motions are highly attenuated from the lower (street-level) motions because of the long travel distances up the buildings. High-rise structures are far stiffer than mid-rise and residential structures and can withstand ground vibration amplitudes far greater than the currently enforced blasting limits in New York City.

Jan 1, 2015

By H. Matsuoka, M. Kawata, K. Mitsuhashi, C. Tokoro, T. Kato

Copper sulfide minerals such as chalcocite, bornite, and chalcopyrite exhibit high floatability, thus they can be recovered as a froth product by adding only a collector in flotation process. However, when their surface is oxidized, the floatability decreases and the simple addition of collectors is no longer effective. In this case, flotation activators are required to improve the floatability. Sodium hydrosulfide (NaHS) acts as an activator for chalcocite and bornite by re-sulfurizing their oxidized surface portions. Nevertheless, the flotation conditions still require optimization in order to achieve a satisfactory recovery of copper minerals. This work addresses the study of the effect of pH and NaHS dosage on the flotation of a complex Chilean copper ore containing chalcocite, bornite, and chalcopyrite. Flotation experiments were conducted using a Denver-type flotation cell and by investigating the effect of two NaHS dosages (50, 100 g/t) and three pH values (8, 9, 10). Following this process, the surface interaction between the minerals and NaHS were analyzed using zeta potential measurements. INTRODUCTION In recent years in the mining area of metal resources, the complexity of ores and the fineness of grind required to liberate minerals have become serious problems. When ores are complex, several valuable minerals may interact with each other and reactions may become more complicated compared with an ore containing only one valuable mineral. Therefore, more processing steps may be required than for a simple ore. When the valuable minerals exist as fine grains, it is difficult to liberate them and more grinding time is required. Furthermore, the probability of collision of fine particles with bubbles in the flotation process declines and it takes much time to recover them. Flotation is one of the most applied methods to separate valuable minerals from unwanted ones using the difference of hydrophobicity (or hydrophilicity). In the flotation method, the air is fed to a cell filled with the pulp of the mineral of interest and agitation is implemented to introduce air and generate bubbles. The hydrophobic particles attach themselves to the bubbles and float along with the bubbles while the hydrophilic particles remain in the pulp. Copper sulfide minerals such as chalcocite (Cu2S), bornite (Cu5FeS4), chalcopyrite (CuFeS2) are widely known abundant copper resources. Generally, flotation is used to recover and concentrate these minerals. Copper sulfide minerals usually have high floatability. However when their surfaces are oxidized, their floatability becomes lower. When the sulfide surfaces are oxidized, activators are added before flotation to modify the surface property of the Copper sulfide minerals so that they can be floated. Sodium hydrosulfide, NaHS, is known as one of the activators. Zhao (2018) reported that NaHS is often used as a sulfurizer for oxidized sulfide minerals (Becker (2014), Clark (2000), Newell (2006), and Newell (2007)). In earlier work, the authors performed flotation tests on a sample of Chilean copper ore which contained chalcocite, bornite, and chalcopyrite using a Denver-type flotation apparatus. The sample was ground to P80 70 µm with a rod mill and ball mill. In these tests, the following conditions were used: natural pH (about pH 8.5), flotation time of 45 min, 60 g/t AP3477 (sodium diisobutyl dithiophosphate) as collector, and MIBC (methyl isobutyl carbinol) at appropriate dosage as frother. NaHS was applied at the dosage of 0, 67, and 120 g/t, respectively at the conditioning. The concentrates were collected at 6, 18, 30, and 45 min. The weights of the concentrates and tailing were measured and they were assayed for copper by ICP-AES (Optima 5300 DV, PerkinElmer Inc.). The flotation recoveries of the copper minerals were calculated from the results of MLA (mineral liberation analyser) (MLA 650, FEI) measurements.

Jan 1, 2019

By D. C. Panigrahi

The paper presents the development of a thermodynamic based network analysis model. It uses transient heat flow algorithm for computing the heat flow from strata and predicts the environmental condition in different branches of the network. Along with the environmental condition, the mass flow distribution in network is computed by using nodal pressure method based on linear theory approach. The algorithm has been coded using object oriented programming approach and it has been validated in actual field condition. The correlation is satisfactory.

Jan 1, 1997

By E. P. Mathewson

THE OLD Pueblo smelter is being dismantled after 43 years of continuous operation, from 1878 to 1921. It was built by Mather and Geist, on a bluff overlooking the Arkansas River just below the, city of Pueblo. At the time of its construction Pueblo was considered a most favorably situated town for a custom smelter. Coal, coke, fuel, limestone, iron ore, lead, silver, and, gold ores were plentiful. It was a "downhill pull" from all directions to Pueblo. Labor, both common and skilled, was plentiful and efficient. Leadville was in bonanza and there were not sufficient furnaces in Colorado to handle the ore offered. The plant prospered from the start. It soon required more capital; so the owners; with the assistance of Thomas Nickerson of Boston, at that time prominent in the affairs of the A., T. & S. F. railway, formed the Pueblo Smelting & Refining Co. About this time, also, very heavy shipments of rich silver ore from New Mexico began to come in. Agencies were established for the purchase of ores in the most important mining camps in the country from Kingman, Ariz., to Butte, Mont. Highly siliceous silver-bearing ores from Butte were shipped to Pueblo in train loads. This was used chiefly in the concentration of leady mattes. RECOLLECTIONS OF MR. GEIST, FOUNDER OF PLANT Mr. Geist is living in Guadalajara and has sent the following brief letter: "Early in 1878 the firm of Mather & Geist, which had been operating in Utah and had then closed their smelter there, after diligent search for a new location selected Pueblo. We erected the first smelter in the valley, blowing in the first furnace in 1878. Mather & Geist carried on until January, 1882, when they transferred all their business to the Pueblo Smelting & Refining Co., which had been organized in December, 1881. Full details of this transfer are given in the enclosed Report, which was issued early in 1882, for the purpose of interesting more capital, in which we succeeded admirably. "I personally did all the work of manager and super-intendent, some job in these days. My technical quali-fications were that I was a member of the class of 1866, Yale Sheffield Scientific. I was born in 1848, so was the youngest member of the class.

Jan 11, 1923

By T. K. Matthews

Minerals are mined as a one-time crop, and the processing of one ton of ore results in there being one ton less to be recovered from the deposit. Although some minerals occur in greater abundance than others, they are to a greater or lesser degree exhaustible. Depletion Allowances One of the distinctive features of the mineral industries is the allowance for depletion. The depletion allowance is a much maligned and misunderstood principal of our tax structure. Although imperfect in design, it has nevertheless served as a constructive incentive for the development and expansion of the minerals industry.

Jan 1, 1969

By John Jordan, Tesarik, Steven J. Knoll, Theodore J. Williams, David K. Denton, Douglas F. Scott

Highly stressed rock in stopes continues to be a primary safety risk for miners in underground mines because this condition can result in failures of ground that lead to both injuries and death. Personnel from the Spokane Research Laboratory of the National Institute for Occupational Safety and Health studied two methods for identifying stress in rock. A seismic tomographic survey, finite-difference analysis, laboratory measurements of compression wave (ultrasonic) velocities in rock cores, and site geology were integrated to evaluate the use of seismic tomography for identifying induced pressures in an underground pillar at the Edgar Mine, Idaho Springs, CO. Electromagnetic (EM) emissions were also investigated in the Galena Mine, a deep underground mine in Idaho, in an effort to determine if these emissions could be used as indicators of impending catastrophic ground failure. Results of this research indicated that (1) seismic tomography appears to be a useful tool for determining relative stress in underground pillars, while (2) EM emissions do not appear to be significant precursors of impending catastrophic ground failure.

Jan 1, 2004

By Victor F. Hollister

North American ophiolite complexes are known to contain significant volcanogenic sulfide only in the following five areas: Newfoundland; Quebec; Applegate, Oregon; Rogue, Oregon; and Orca, Alaska. Most North American ophiolites, including the Baltimore, Kings-Sierra Nevada, and Del Puerto complexes, and those associated with the Franciscan, Trinity, eastern Oregon, and Cache Creek groups lack significant volcanogenic sulfide. The characteristics of sulfide-bearing ophiolites are: (1) manganozls cherts, and (2) fine, carbonaceous clastics inter- calated with pillow basalt and chert. It is suggested that sulfide- bearing ophiolite complexes developed in a restricted basin environment, such as is now present in the Gulf of California; whereas sulfide-poor ophiolites, formed in midocean, rises distant from land masses. Sea floor oxidation makes the typical midocean ridge configuration not conducive to sulfde preservation, whereas spreading centers bounded by land masses are more likely to produce anoxic physiographic lows favorable to sulfide accumulation.

Jan 1, 1982

By F. Parada Luna, F. Parada Torres, J. Salvo, A. Reghezza

In the pyrometallurgical processes of copper concentrates, arsenic is preferentially concentrated in the dusts carried by the gases as a result of their volatility and subsequent condensation in the gas cleaning train. In this work results obtained by alkaline leaching of the dusts from Ministro Hales roasting plant, belonging to Codelco, are presented. For the Ministro Hales plant the alkaline leaching would be an alternative to the recirculation of dusts to the roasting furnace. The experimental study considered NaOH and NaOH plus NaHS leaching of two samples of dusts, with 4.24 and 2.55% arsenic respectively. The results show that it is feasible to extract 90% of the arsenic and 50% of the antimony at room temperature using only NaOH, and when the temperature increases to 95ºC, the extractions of As and Sb increase. Copper remains in the solid residue with less than 1% dissolution, and the NaOH net consumption was approximately 140 kg/t of dust. In leaching tests with NaOH + NaHS, two types of methods were tested, baking plus leaching with water and direct leaching with a NaOH+NaHS solution. With the second method arsenic extraction increased to 95% and copper dissolution was less than 0.01% at 85ºC, NaOH 100 g/L, NaHS 90 g/L, 1.5 h and L/S ratio of 5/1 (L/kg). The bismuth remains stable in the solid in all cases. INTRODUCTION The presence of arsenic in copper concentrates has increased with time and the environmental regulations are becoming increasingly more stringent. In concentrate treatment pyrometallurgical plants, most of the arsenic is volatilized condensing in the gas train and is collected along with the entrained solids to form the flue dusts. Under these conditions, in smelters of copper concentrates with high arsenic content, the dusts are being treated in hydrometallurgical plants to extract and stabilize the arsenic, which also means that most of the copper contained in the dust is co-extracted with the arsenic. This affects the recovery of copper in the smelter and an alternative such as the selective alkaline leaching of arsenic, would allow the copper from flue dust to be recovered.

Jan 1, 2019

By H. C. George

CAREFUL- sampling and good judgment as to probable recoveries are important factors in estimates of ore reserves, based on prospecting drilling results, but other factors are equally as important and may be more misleading and perhaps disastrous if not properly interpreted. Some of these are: 1. The case where no, ore is shown in the "sludgings," when, as a matter of fact, the drill has passed through a thick sheet of ore which has been broken up and washed away into open crevices. In numerous cases, later mining operations have shown that this has happened. This condition may be discovered by shooting the drill .hole at the point where the open crevices occur, but shooting should not be done until after the drill hole is completed, because the resulting shattered formation may salt the drill hole at lower levels. 2. The case where rich cuttings are shown for a thickness of 20 or 30 ft., when ore was encountered in only the first sludging. Owing to soft or loose formation, the ore from the first sludging has salted the lower sludgings. The presence of large pieces of ore and a similar ratio between zinc and iron assays in the lower sludgings frequently indicate this condition. In the lower sludgings, the presence of oxidized ore in unaltered limestone sometimes shows this condition. 3. The case where the drill hole shows a considerable thickness of ore; but owing to the presence of a vertical sheet of ore, perhaps not more than 1 in. thick, at the place where the drill hole is located, the good assays resulting might be misleading. If this condition is suspected, the drilling of several more holes within a distance of 10 or 15, ft. will usually show it.

Jan 1, 1921

ANY discussion of State-supported schools of mining and metallurgy needs to be prefaced by a definition, since the first school to offer a mining curriculum, the Pennsylvania. Polytechnic College, was established by a grant from the State. But, so far as can be determined, it received no further State support. It would be tiresome to go into precise details, and it will be enough to stipulate that by State schools are meant those which derive their main financial support from regular appropriations made by a State legislature. The University of Michigan was the first of these to. offer a mineral industry curriculum; its story, as well as those of Wisconsin and Illinois, has been related in the preceding chapter.* Arranging the others in chronological order involves making a decision as to what weight to attach to plans for giving instruction, as contrasted with its effective initiation. This may appropriately be illustrated by the history of mineral industry education in California. CALIFORNIA Among those who came to California in 1849 and the following years were many New Englanders who had a keen interest in education. Some of them, mostly Congregationalists and Presbyterians, sought to establish a school of higher education around San Francisco Bay and eventually succeeded in opening the "Scientific and Classical School at Contra Costa" in Oakland, at Broadway and 5th St., on June 90, 1853. This prospered so well that it was chartered by the State as the College of California" on April, 13, 1855. Developing so rapidly that its quarters became. cramped, in 1864 it not only bought a tract of

Jan 1, 1941

By Lester G. Morrell

AGAIN in 1963, as in nearly every year since 1946, the Canadian mineral industry has established a new national record in value of mineral production. The 1963 estimated total value of $2,976 million is 5 percent higher than the 1962 value of $2,845 million.2 As in previous years, metals made up more than half the value of total production. For selected years since 1949 the category percentages and total value are as follows: [ ] Crude petroleum, Canada's most valuable mineral product, accounted for 21 percent of the total value of minerals in 1963. In descending order came nickel 12 percent, iron ore 10 percent, copper 10 percent, gold 5 percent, and uranium 5 percent. Asbestos accounted for 5 percent, sand and gravel 4 percent, and cement 4 percent. The complete list of Canada's mineral products includes more than 50 basic commodities.

Jan 1, 1964