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"Pilot plants for pressure hydrometallurgy represent special design and project execution challenges. Over the past twenty years, Zeton has designed and fabricated a variety of world-class pressure hydrometallurgical pilot-plant facilities, and this paper discusses design considerations and strategies related to such projects. Project execution methods are also discussed, and guidance is given for the selection of materials of construction and for the selection of appropriate pressure and temperature design points for pressure hydrometallurgical pilot equipment. The paper concludes with a discussion of the need for process similarity with future commercial operations and the realities of pilot-scale equipment.INTRODUCTIONThe process technology developer or owner and the designer/fabricator of a new pilot-plant facility are faced with some difficult technical choices even after the decision to build a dedicated plant has been taken. A pilot-plant project is usually on the critical path of a large commercial project involving investments many multiples greater than the capital cost of the pilot plant. Schedule savings in the design, manufacture, and commissioning of the pilot plant or in a rapid completion of the experimental program can be disproportionately beneficial to the overall development project. However, inappropriate shortcuts resulting in major oversights can be disproportionately problematic.A number of considerations and suggestions for both the project execution approach and the process engineering design of pressure hydrometallurgical pilot-plant facilities are presented as a guide for potential owners and operators of new pilot-plant equipment and facilities."

Jan 1, 2012

By Patrick Wong, Gareth Hatch, M. A. Halim, V. I. Lakshmanan, Darcy Tait

"This paper describes development of an integrated chloride process for separation and purification of REEs. The process includes atmospheric leaching of ore/concentrate with mixed chloride lixiviant containing HCl and MgCl2 followed by bulk recovery of REEs, dissolution of the bulk intermediate product, and separation of individual REEs by solvent extraction (SX) process steps. Mixed chloride leaching technology provides the opportunity to regenerate the lixiviant, while the addition of MgCl2 in HCl enhances the hydrogen ion activity by orders of magnitude increasing REE extraction efficiency at a lower concentration of HCl. An individual REE separation process developed by Innovation Metals Corp. is being piloted at a state-of-the-art facility at Process Research ORTECH Inc. in Mississauga, Ontario, Canada. The SX process includes the separation of light REEs (La – Nd), medium REEs (Sm – Gd) and heavy REEs (Tb – Lu plus Y) from leach liquor followed by individual REE separation. Each SX circuit proceeds by multistage extraction followed by scrubbing and stripping. The process is chloride based and reagents are recycled, reducing waste generation and optimizing water usage to reduce environmental impact.INTRODUCTIONRare earth elements (La to Lu plus Y) exhibit a range of unique magnetic, electronic, catalytic and optical properties. Due to these special properties, the application of REEs is increasing and they are found in components for wind power generation, hybrid electric cars, catalytic converters, and many electronic devices.Rare earth elements (REEs) are commonly divided in two groups: light rare earth elements (LREEs) and heavy rare earth elements (HREEs). Light rare earth elements include elements from lanthanum (La) to neodymium (Nd). Although promethium (Pm) is considered an LREE it is unstable and scarcely occurs in nature and is generally excluded. Heavy rare earth elements include elements from samarium (Sm) to lutetium (Lu) plus yttrium. Although rare earth elements are not rare and the rare earth oxides are scattered around the globe, over 95% of REEs+Y are currently produced in China (Pitts, 2011). On one hand the Chinese government is restricting the export of rare earth elements and on the other hand the demand for REEs+Y is increasing in the rest of the world. This has created an imbalance in the supply and demand of rare earth elements and has led to a rush for developing new rare earth projects."

Jan 1, 2016

By J. Beland

The Rimouski-Matapedia region is along the southwestern extension of the central Siluro-Devonian synclinorium of Gaspe Peninsula. As in Gaspe about 30,000 feet of Siluro-Devonian strata rest on a "basement" of tightly folded Ordovician rocks. The central synclinorium is divided up into two northeasterly trending belts each of which is characterized by distinctive lithologies and patterns of folding. The northwestern belt is gently to moderately folded and includes lithologies which point to a stable environment. The southeastern belt on the other hand is tightly folded and the lithologies indicate a less stable environment. A marked angular unconformity separates the basement from the Siluro-Devonian cover near the north-western margin of the northwestern belt. At the southeastern margin of the southeastern belt the relationship of cover to basement has not been as-certained because of a fault. The northwestern belt has several features significant in the search for petroleum; the Silurian strata are exposed in broad open anticlines

Jan 1, 1962

By R. E. Eyre

ALTHOUGH the idea of roasting zinc concentrates in suspension had intrigued investigators for a number of years, no commercial application of a process appeared successful until the development of the "Cominco" process. The efficiency and high capacity of this process may be judged by the fact that nearly all other electrolytic plants and many zinc retort plants in the world use this method. A furnace of the Cominco type can roast without special preparatory treatment and without supplementary fuel, mineral sulphides such as zinc sulphides and iron sulphides containing varying amounts of moisture at any desired rate ranging from one-half up to full capacity. The full capacity of a unit is in general about three times that of a multiple hearth furnace of the same size. The latest type of "Cominco" furnace can be built for capacities from 25 to 500 tons per day. The quality of the calcine is subject to positive control and may be

Jan 1, 1961

By A. J. Makoka, B. C. Qi

Reliable monitoring of corrosion is vitally important in the combat against corrosion and over the last two decades the interpretation of electrochemical noise has received considerable attention as a means to discriminate between different types of corrosion. To this end, many different analytical methods have been proposed, such as power spectral density analysis and analysis via various other stochastic criteria. However, although many corrosion systems are nonlinear and therefore not readily interpretable by the abovementioned analytical approaches, few studies in the analysis of electrochemical noise to date have exploited advances made in the analysis of nonlinear systems. In this paper, the use of phase space methods to analyze and detect change in corrosion systems via electrochemical noise is considered. In particular, the electrochemical noise data are used to reconstruct trajectories in the so-called phase space of the system and changes in the topology of these trajectories or attractors as represented by correlation dimension curves are consequently interpreted as an indication of change in the dynamics of the system.

Jan 1, 2005

By K. Winterton, Carruthers. J.

"Attempts have been made to produce hardened structures of a pseudomorphic type in various carbon and alloy steels. In order to obtain martensite with a fine distribution of cementite, an initial structure of fine lamellar or nodular pearlite is required; this may be obtained by conventional means. This is followed by partial austenitization and quenching.Two methods have been tried to induce partial austenitization:(a) A resistance (direct current) heating method involving rapid entry into the austenite field.(b) A new method, described as the ""threshold"" technique, involving homogenization of temperature just below A 1, followed by entry into the austenite field; two furnaces are required.The resulting structures have been examined for microstructures, hardness, tensile, and impact values. The tensile properties are comparable with those obtainable by conventional treatment methods. Impact values are disappointing, but this is explainable from the nature of the manifold changes occurring."

Jan 1, 1960

By Stanley W. Holmes

"The discovery of extensive uranium mineralization on the Pronto property in April 1953 initiated a program of staking, exploration, and development unparalleled in Canadian mining history. Within twelve months of the discovery hole, sufficient ore had been blocked out to merit a 55-million-dollar contract with Eldorado Mining & Refining Co. On October 15, 1955, two years and four months after discovery, Pronto went into production with a mill rated at 1,000 to 1,500 tons per day. The property is on the southern edge of the Algoma uranium district, 10 miles east of the town of Blind River and close to the Canadian Pacific Railway and Highway 17. Docking facilities for Great Lakes steamers are avail-able at Spragge, 4 miles to the east.The data and conclusions presented in this paper are based on field studies, drill hole information, and underground development. The ideas of ore genesis are those of the writer, and will undoubtedly be modified as more detailed studies and research are carried out. Because of security regulations, information pertaining to grade and tonnage will not be discussed.GeologyThe general geology of the Algoma basin has been outlined in a pre-ceding paper (Joubin and James). The description below is concerned essentially with the rocks most closely associated with the Pronto deposit. They may be grouped in three structural and lithological units: (1) the pre-Huronian basement, (2) the Mississagi formation, the lowest member of the Huronian sediments lying unconformably on the basement, and (3) a series of basic intrusives cutting (I) and (2). Most of the uranium mineralization occurs in a quartz-pebble conglomerate forming the basal member of the Mississagi quartzite."

Jan 1, 1949

By A. G. Darnley

"The Geological Survey of Canada is devoting consider-able effort to finding ways to make airborne radiometric measurements both quantitative and reproducible. Equipment has been designed by Atomic Energy of Canada Ltd. to provide high count rates in order to minimize statistical uncertainty, this being essential to justify applying terrain clearance and Compton scattering corrections to the data. Correction factors have been determined experimentally and can be applied automatically. Considerable ground work has been undertaken in parallel with equip-ment development in order to determine field parameters.Two airborne gamma-ray spectrometers are described. One is based on three 5-by 5-inch Nal(Tl) detector crystals and is used in a helicopter; the other employs twelve 9-by 9-inch detectors and is used from a Skyvan aircraft. The former is being used to investigate the range of radiometric response from specific rock types, and for the correlation of ground and air measurements; the latter has completed initial trials and will be commencing experimental surveys during 1969.Results are given to show the comparative sensitivities of the various detector sizes, and operational requirements for a gamma-ray spectrometer survey are discussed briefly."

Jan 1, 1970

By R. F. Coulter

THE Flin Flon concentrating and metallurgical plants (Figure 1) of the Hudson Bay Mining and Smelting Co., Limited, lie adjacent to the town of Flin Flon, on the Manitoba-Saskatchewan border, 400 miles northwest of Winnipeg. Since the start of milling operations in 1930, over 50 million tons of ore from the Flin Flon mine have been treated in the concentrator. During the past few years, newly discovered orebodies have been brought into production and their ores processed at the company's main metallurgical plants. All these properties are within a 75-mile radius of Flin Flon and have aided substantially in augmenting plant metal production as well as retarding depletion of ore reserves in the Flin Flon mine. •Current satellite producers are the Schist Lake, Coronation, and Chisel Lake mines. The Schist Lake mine, located 3 ½ miles southeast of the main plant, is a copper-zinc producer. It was brought into production in 1954. The

Jan 1, 1962

By Frederick W. Breaks, Andrew G. Tindle, Julie B. Selway

"Abstract - Rare-element pegmatites may host several economic commodities, such as tantalum (Taoxide minerals), tin (cassiterite), lithium (ceramic-grade spodumene and petalite), and cesium (pollucite). Key geological features that are common to pegmatites in the Superior province of Ontario and Manitoba, Canada, and in other large tantalum deposits worldwide, can be used in exploration.An exploration project for rare-element pegmatites should begin with an examination of a regional geology map. Rare-element pegmatites occur along large regional-scale faults in greenschist and amphibolite facies metamorphic terranes. They are typically hosted by mafic metavolcanic or metasedimentary rocks, and are located near peraluminous granite plutons (A/CNK > 1.0). Once a peraluminous granite pluton has been identified, then the next step is to determine if the pluton is barren or fertile. Fertile granites have elevated rare element contents, Mg/Li ratio < 10, and Nb/Ta ratio < 8. They commonly contain blocky K-feldspar and green muscovite. Key fractionation indicators can be plotted on a map of the fertile granite pluton to determine the fractionation direction: presence of tourmaline, beryl, and ferrocolumbite; Mn content in garnet; Rb content in bulk K-feldspar; and Mg/Li and Nb/Ta ratios in bulk granite samples. Pegmatite dikes with the most economic potential for Li-Cs-Ta deposits occur the greatest distance (up to 10 km) from the parent granite.Metasomatized host rocks are an indication of a nearby rare-element pegmatite. Metasomatic aureoles can be identified by their geochemistry: elevated Li, Rb, Cs, B, and F contents; and by their mineralogy: presence of tourmaline, (Rb, Cs)-enriched biotite, holmquistite, muscovite, and rarely garnet.Once a pegmatite dike has been located, the next step is to assess its potential to contain Ta mineralization. Pegmatites with the highest degree of fractionation (and thus the most economic potential for Li-Cs-Ta) contain blocky K-feldspar with >3,000 ppm Rb, K/Rb < 30, and >100 ppm Cs; and coarsegrained green muscovite with >2,000 ppm Li, >10,000 ppm Rb, >500 ppm Cs, and >65 ppm Ta. Pegmatites with Ta mineralization usually contain Li-rich minerals (e.g., spodumene, petalite, lepidolite, elbaite, amblygonite, and lithiophilite) and may contain Cs-rich minerals (e.g., pollucite, Cs-rich beryl). The ore minerals of Ta are commonly manganotantalite, manganocolumbite, wodginite, and microlite; Ta-rich cassiterite is also commonly present. Tantalum mineralization tends to occur in albitic aplite, mica-rich (lepidolite, cleavelandite ± lepidolite), and spodumene/petalite pegmatite zones."

Jan 1, 2005

By U. Dillon, G. Blackwell

"Geographic information systems (GIS) provide an efficient means for the recording, manipulation, revision, display and analysis of spatially referenced data. GIS are widely used at the exploration stage of mine development, and are increasingly used for reclamation planning. The ability of a GIS to perform spatial searches and query spatially referenced data make it a powerful tool for use at all stages of mine development. As the amount of data available for analysis increases, so does the power and flexibility of GIS as a planning tool.Starting from the exploration database, this paper describes how a GIS can be used for the development of mining plans based on topography, geology and mineralization information stored in a relational database. Planning decisions approaching the optimal can then be made for a wide range of parameters, including stockpile and waste dump locations, the location of potentially acid generating and neutralizing material for dump design, profitable and risk-controlled mine extraction sequencing, and haul road locations. This is made possible by the overlay and buffer analysis capabilities of a GIS which are explored and exploited to produce a continuous mine production planning program, as well as site remediation and reclamation using a successful case study. IntroductionGeographic information systems (GIS) are a relatively new tool in the mining industry. Although they have existed for a number of years, the potential of GIS for mine management and planning is only beginning to be investigated and exploited. The unique spatial capabilities of GIS make them particularly wellsuited for use in mining, where spatial information is fundamental to the processes of mineral exploration, mine development, and environmental reclamation. A number of potential applications for GIS in the mining industry have been identified, and they are widely used for exploration and reclamation. The use of a GIS as a platform for the development of mine planning routines and software remains an interesting, but as of yet unexplored, application of this technology."

Jan 1, 2003

By T. Sugawara, S. Hara, Y. Mitsui

Surfaces of rock slopes in cold regions often become frozen in winter. Therefore, understanding time-dependent behavior of frozen rock, as well as that of unfrozen rock, is important for long-term stability assessment of rock slopes. In this study, a series of uniaxial compression tests and creep tests were carried out on Shikotsu welded tuff under dry and water-saturated conditions at -20 °C to clarify timedependent strength and deformation of the frozen rock. The influence of water content on them also was investigated. It was found that the amount of deformation of the water-saturated specimen was much greater than that of the dry specimen. It also was found that the creep behavior of the water-saturated specimen was similar to that of polycrystalline ice. These show that deformation of the water-saturated specimen is strongly affected by pore ice. The UCS of the water-saturated specimen was approximately equal to that of the dry specimen at a strain rate below 4.2×10-6/s, and its value was about 17 MPa. However, the former increased up to 26 MPa at 4.2×10-4/s with loading rate, whereas there was little increase in the latter. This means that the UCS of the water-saturated specimen was always greater than that of the dry specimen at higher strain rates. The creep life of water-saturated specimens was longer than that of the dry specimens at stress level greater than 15 MPa. These results of UCS and creep life show that inclusion effect due to presence of pore ice plays an important role on strength of the water-saturated specimen. Creep life of the non-failure specimen that was loaded for more than three days was estimated by the relationship between creep life and axial strain rate at 10 s on failure specimens. It was found that creep life of the water-saturated specimens was shorter than that of the dry specimen at stress levels less than 14 MPa. This suggests that estimation of creep life of frozen rock under water-saturated condition is important for the stability assessment of frozen rock slopes. It was clear that the loading-rate dependency of UCS was related to the stress-level dependency of creep life in both dry and wet conditions. This indicates that there are common fracture mechanism in creep and uniaxial compression tests. It also indicates that the creep life can be estimated by the relationship between the UCS and the loading rate. The time dependencies of the water-saturated specimen were in good agreement with those of polycrystalline ice. This confirms that pore ice strongly affects the strength of the water-saturated specimens as, well as the deformation behavior.

Jan 1, 2015

By John D. Campbell

Alberta Plains coals exhibit an almost rectilinear system of vertical fracturing called "cleat", which is best traced by mapping true bearings of underground coal mine rooms. The cleat pattern is approximately conformable with a pattern of surficial features and a pattern of bedrock jointing in the Alberta Plains, and with the trend of the Rocky Mountain Trench, but not with the distribution pattern of coal rank nor with the trend of the eastern boundary of the Rocky Mountains and Foothills physiographic province. The processes resulting in cleat remain in doubt, but cleat is always of practical importance in extracting coal from deeply buried deposits.

Jan 1, 1979

By T. K. Dichmann, J. A. Finch

"Microflotation, laboratory batch, and in-plant minicell continuous tests were conducted to determine if copper ions not only activate sphalerite but also depress pyrite when the minerals are together. Microflotation tests showed that pyrite recovery increased with addition of copper ions in the pH range of 5-10 when alone, but decreased when sphalerite was also present. Batch flotation tests (Red Dog ore) showed that upon addition of copper, pyrite recovery decreased significantly. The continuous tests (Louvicourt Mine) confirmed this and indicated that with excess copper pyrite recovery can increase. The results suggest there is competition for copper and xanthate in favour of sphalerite. To take advantage of this competition it may be necessary to control the sequence and rate of copper, collector, and lime addition. INTRODUCTIONFlotation, in common with all physical separations, is an imperfect process that results in misplacement of minerals. One source of this imperfection is accidental activation by contaminating metal ions. An important practical example is the misplacement of pyrite to zinc concentrates. Flotation of sphalerite generally requires activation by copper ions, added as copper sulphate. Copper ions are also used to activate pyrite [l] hence there is the suspicion that accidental activation contributes to the recovery of pyrite (Py) with the sphalerite (Sp). However, recent literature has shown that copper ions may make Py less floatable if Sp is also present. Xu et al. [2] conducted continuous minicell tests in-plant at Kidd Creek Operations (division of Falconbridge Ltd.) and showed that while the addition of copper sulphate improved zinc/iron selectivity, it did so as much by reducing the recovery of pyrite as increasing zinc recovery (Figure 1)."

Jan 1, 2000

By M. Bigdeli Karimi

In this study, the effect of strain level and holding time in semisolid temperature range via SIMA process on AS21 Mg alloy was investigated. Some cylindrical samples of this alloy with 1cm in height and 2.5cm in diameter (H/D=0.4) were compressed to 10%, 20%, 30% and 40% at 300-C. Then, the samples were reheated in semisolid temperature range at 614°C for various times. The results of optical microscopy and image analysis showed that with increasing of strain and holding time, dendritic structure changed to equi-axed structure, gradually. Also, the best conditions to obtain good globular structure were achieved. Furthermore, it was seen that after compression and reheating, Mg2Si intermetallics with Chinese script morphology converted to dispersed-fine particles which were distributed into the ci-Mg grains.

Jan 1, 2007

By B. C. Tripathy, S. K. Padhy, R. K. Paramguru, Pinak Patnaik

"Cobalt is regarded as technology enabling metal among the less abundant metals found in the earth crust. Electrodeposition of the metal from aqueous sulphate solutions is the preferred technology for its commercial production. Certain additives are added in the electrolytic bath during electrodeposition for the production of uniform, smooth and bright deposits of cobalt metal with higher current efficiencies and lower energy consumptions. A detailed investigation has been carried out to determine the effect of additive Sodium octyl sulphate (SOS) on the electrodeposition of cobalt. The results indicated that the additive apart from increasing the current efficiency enhanced the quality of cobalt electrodeposits. A maximum current efficiency of 98.4% was achieved at 10 mg/L SOS. The presence of SOS in the electrolytic bath did not result in any noticeable change in the crystal orientation of the cobalt electrodeposits except at higher concentrations (50 g/L) of the additive. Scanning electron micrographs indicate that smooth, compact and uniform deposits of cobalt were obtained at 10 mg/L of the additive beyond which there is detoriation in the quality of deposits. Polarisation of the cathode was seen in the presence of SOS. The effect of SOS on the electro kinetic parameters: Tafel slope (b), transfer coefficient (a) and exchange current density (I0) has also been investigated.INTRODUCTIONCobalt is recognised to be a strategic metal among the various base metals, owing to its numerous applications in various industries. Cobalt as a metal finds its use in the preparation of rechargeable batteries, as an alloying component in the manufacture of space craft and jet engines, as a drying agent for paint varnishes, ground coats for porcelain enamels and in the manufacture of the catalysts for the petroleum and chemical industries (Davis, 2000). Although there is a huge demand of the metal the supply of the metal is limited due to its scarcity in the earth crust. The metal comprises of only 0.02% of the earth’s crust for which the metal is recovered from various ores of nickel and copper as a byproduct (Hawkins, 1998). The present day techniques for cobalt production includes mostly hydrometallurgical methods which are preferred over the earlier used pryometallurgcial methods carried out for the metal production. Almost 70% of the world’s cobalt produced currently is from hydrometallurgical techniques in which electrodeposition of the metal from aqueous solutions is the final step for metal production (Verney, 1988). The most preferred route for electrodeposition of cobalt metal involves a sulphate medium (Das and Subbaiah, 1984; Lenthall and Bryson, 1997; Sharma et al., 2005)."

Jan 1, 2016

By C. Lambert

It has been shown that contacts between host rock and engineered barriers may be critical in the design of deep radioactive waste repositories. Water is expected to reach the interface zone after the re-saturation of the geological massive and its presence may lead to concrete leaching. Such a phenomenon could increase the interface transmissivity and compromise the confinement of radioactive waste. Recent experimental results from Buzzi et al. (2008) have enhanced how concrete leaching can drastically change the mechanical behaviour of such interfaces. Because of the local loss of strength resulting from leaching, shearing resulted in a degradation of the interface asperities. Similarly to rock joints, intact interfaces exhibit a usual contracting-dilating behaviour. On the contrary, depending on the extent of leaching, the degraded interface can display a fully contracting. This paper intends to investigate the influence of concrete leaching on the mechanical behaviour of host rock-concrete interfaces. The leaching process consists in the dissolution of some of the hydrates of the cement paste, leading to a reduction of the strength and Young&apos;s modulus. A discrete model has been developed with PFC3D where a simplified interface morphology has been introduced using a saw-tooth description of the asperities.

May 1, 2009

By Robert Harris, Peter Pheeney

"The Murray Brook gold mine operated from September 1989 to March 1991. Approximately 1.2 million tonnes of gossan were mined from an open pit and treated at a rate of 900 tonnes per day. The facility applied an agglomeration vat-leaching cyanidation plant for gold and silver recovery. The leached ore or tailings were rinsed of residual gold and cyanide and placed on an adjacent clay lined pad for storage and containment. A 50,000 tonne heap-leach demonstration project was constructed at Murray Brook in 1992 to recover copper and zinc from ore located in a sulfide-rich zone occurring beneath the gossan. The operation proved unsuccessful because of poor recoveries and low metal prices. The project terminated in the same year.A corporate decision was made in September 1999 to undertake complete and final reclamation of the Murray Brook site. Jacques Whitford and Associates Limited were contracted to develop the final reclamation plan and to assist the company in presenting the plan to the New Brunswick government for approval. The government approved the plan in January 2000. Two important reclamation issues were the mobility of mercury from the gossan tailings and the potential of acid mine drainage from exposed sulfides. The mine site is situated upstream of a productive river system, and the issue or impact of chemistry changes to the environment over the long term became an overriding factor in the development of the reclamation plan.A resource assessment of the gossan tailings in 1999 indicated an average concentration of mercury of 40 ppm. The mercury occurred naturally as the mineral cinnabar, but the exposure to residual cyanide (less than 10 ppm) over several years in the pile has likely caused much of the cinnabar to decompose into more soluble mercury forms. The reclamation plan specified the replacement of all sulfides to the pit followed by approximately 600,000 tonnes of gossan. To ensure “fixing” of the mercury, the gossan was replaced in compacted lifts and both the remaining pile and that replaced to the pit covered with available till and compacted. The reclamation work was successfully completed in September 2000 and the chemistry of the receiving environment will be monitored over a three-year period, after which the company expects to achieve walk away conditions."

Jan 1, 2001

By D. J. McCulla

Mineral development and utilization affect the health of the economy and the pattern of long-term development throughout Canada. There are many diverse opinions on the contribution of minerals to the economy, but there is a dearth of adequate quantitative information. This paper discusses some recent research and provides some new information.

Jan 1, 1977

By W. H. Hannay

Introduction The subject matter of this paper will be treated under two heads: (1) experimental work and the development of the purification system, and (2) the operation of the commercial plant. During 1927-28, a two-ton slag-retreating plant was in operation at the smelter for experimental purposes. Details of this operation and of the commercial plant are presented in a paper by G. E. Murray, read before the Annual General Meeting of the Institute in April, 1933 (1). A point which has considerable bearing on the subject of the present paper, and which was not emphasized by Mr. Murray, is the concentration of volatile impurities in the zinc oxide fume produced. The result of the operation of the slag fuming furnace is largely to confine in a closed circuit all the minor constituents of the Sullivan concentrates, both lead and zinc. They pass into the feed of the zinc fuming furnace, with the result that all impurities which volatilize-such as arsenic, antimony, tin, fluorine, etc.-report in the zinc oxide product. The accompanying condensed flow-sheet (Figure 1) will illustrate this. The only outlet for impurities which is not shown is the small tonnage which passes the Cottrell plants. The flow-sheet would indicate the possibility of building up a prohibitive concentration of cathodic impurities in the oxide leaching plant feed. However, after three years&apos; continuous operation this has not occurred. Should this condition arise at some future date, discard of some tonnage of blast furnace slag is indicated. In Mr. Murray&apos;s paper, the much greater flexibility of blast furnace operation, due to the slag fuming furnace, is stressed, particularly as to the lead content of the slag. The requirements of our lead refinery call for a bullion containing about 0.70 percent antimony.

Jan 1, 1934