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By Willem P. C. Duyvesteyn

A novel hydrometallurgical process for Escondida copper concentrates has been developed by The Minerals Laboratory of BHP. The Escondida Process consists of concentrate leaching, solution purification, electrowinning and residue flotation. Part of the copper will be sold as high grade concentrate and part as high purity SX-EW copper. Contrary to previous efforts for the development of a hydrometallurgical process for copper concentrates, this patented process does not advocate the total dissolution of copper. It only aims for the copper that is readily soluble in a mildly oxidizing environment with an ammoniacal or acidic lixiviant. Both lixiviants were studied, but ammonia was preferred because of fast kinetics at ambient temperatures and pressures. By controlling the oxidation potential, the formation of sulfate ions and, consequently, of an ammonium sulfate byproduct, is precluded. These mild leaching conditions also prevent the dissolution of unwanted impurities and result in the production of ultra-high purity electrowon copper. Solution purification is carried out by solvent extraction with LIX-54. The very high loading capacity of this organic results in a compact SX circuit, consisting of two loading, one scrubbing, and one stripping stage. As the organic is selective for simple copper ions, the copper amine complex is broken down and free ammonia is regenerated and recycled for leaching. High purity copper cathodes are produced in a conventional sulfuric acid based electrowinning system. One scrubbing step is needed to separate the ammoniacal circuit from the acid circuit. Limiting copper dissolution to less than 50% also provides an opportunity to produce high grade concentrates by residue flotation. Copper recoveries in excess of 98% with precious metal values reporting to the final concentrate can readily be obtained. Complete breakdown of the copper mineral- pyrite middlings results in a final concentrate grade that can be even higher than the original feed material. The Escondida Process also provides an opportunity to accept lower grade copper concentrates producing improved copper recoveries in the mill and yet high quality concentrates for marketing. The Paul E. Queoeau International

Jan 1, 1993

"An unparalleled growth in the Canadian coal industry in 1970 coincided with increasing awareness by Canadians of their environment and their geography with its accompanying transportation factors. R and D on coal moved with greater emphasis toward solving problems in these areas as well as continuing with strong interest in coal preparation, carbonization, combustion, ""weathering'', spontaneous ignition, storage, exploration and geology. Long-range ""basic"" research was not forgotten in that work continued on coal-based carbons, coal chemistry and agrobiological uses for coal. This paper reviews the status of these many areas of coal research at the beginning of the seventies and takes note of some of the more significant legislation and projects brought to the author's attention. No attempt is made to itemize or to describe in detail all the worthwhile projects, many of which are reported elsewhere."

Jan 1, 1971

[A AALSETH, Earl P (M 51) Consult Geol Engr 2019 Eldorado Dr, Billings, Monl ABADIE, Henry G (M 43) Asst to Supt of Oper Long Beach Oil Dev Co 925 Harbor Plaza, Long Beach 2, Calif ABBE, T Waldo (A 56) Asst Dist Oper Supt Sun Oil Co PO Box 66, Stowell, Tax ABBOTT, Fred E Jr (M 59) Abqaiq Dist Mgr Arabian American Oil Co Dhahran, Saudi, Arabia ABBOTT, Clifton T (A 60) Apartado 677, Maracaibo, Venezuela ABBOTT, J L (M 56) Partner Pritchard & Abbott 1010 Ft Worth Natl Bk Bldg, Fort Worth 2, Tex ABBOTT, Richard H (J 51) Partner Abbott & Howard 422 W Hermosa San Antonio 12, Tex .ABBOTT, William G (M 50) Div Mgr Rice Engrg & Operating Inc Box 1142, Hobbs, N. M. ABDERHALDEN, Ronald R (J 59) Prod Engr Continental Oil Co Box 100, Carmi, III ABEL, Malcolm D (J 50) Gen Partner Abel & Bancroft PO Box 865, Midland, Tex ABEL, Ramond L (M 28) Prof of Chem Eng Univ of Pittsburgh, Pittsburgh 13, Pa ABEL, Wayne K (M 57) 1513 Patton Drive, Odessa, Tex ABELL, Joseph M (J 55) Petr Engr Tennessee Gas & Oil Co Box 1772, Casper, Wyo ABELS, Thomas A (J 60) Exploit Engr Shell Oil Co Box 193, New Orleans 3, La ABENDROTH, G F (M 46) Dring Prod Supt Lyons & Logan 1500 Beck Bldg, Shreveport, La ABERCROMBIE, Bolling A (M 60) Mgr Product Planning Axelson-Garrett PO Box 2427, Longview, Tex ABERCROMBIE, C T (160) Prod Engr Cities Ser Petr Co Box 472, Brownfield, Tex ABERCROMBIE, H L Jr (J 55) Prod Engr Mobil Oil Co Room 1800 Gr PI Life Bldg, Lubbock, Tex ABERCROMBIE, Robert (J 57) Prod Engr Mobil Oil Co PO Box 1770 Shreveport, La ABERG, Richard S (M 57) Area Prod Geol Shell Oil Co of Canada, Box 100 Calgary, Alta, Canada]

Jan 1, 1961

By J. J. Calaman, D. H. Fleming

DURING 1950 the jet-piercing process was used commercially in the piercing of primary blast-holes in magnetic taconite at the preliminary taconite plant of .the Erie Mining Co., Aurora, Minn. The Erie Mining Co. purchased a jet-piercing machine and associated equipment in 1949, and the machine has been in operation since its installation in the summer of that year. An overall view of the pit with the JPM-1 jet-piercing machine in operation is shown in Fig. 1. During three months of 1949 and continuously since February 1950, production piercing took place under all pit conditions. By the end of October 1950, a total of 15,000 linear ft of hole had been pierced in an open pit handling an average of 1200 to 1800 tons of crude a day in one 8-hr shift. While it is recognized that this output does not approach the millions of tons a year planned for the developing Minnesota taconite projects, the machine as a unit has been operating under conditions probably more adverse than those that eventually will be encountered in the large operations. This pilot operation has permitted evaluation of the piercing problem in the full-scale taconite plant. This paper describes jet-piercing process funda- mentals, important features of the latest jet-piercing burners and machine, actual piercing results obtained, and new developments that give promise of materially increasing overall process efficiency. To produce the blasthole, jet-piercing utilizes thermal energy, as contrasted with the application of mechanical energy in churn drills and jackham-mers. The heart of the process may be termed a tailored flame produced by a rocket-type burner, thermodynamically similar in every respect to that of the giant rockets being developed for military purposes. The heat release in the combustion chamber of the burner is about 50x10' Btu per cu ft per hr as compared with 5x10' for most modern steam generators.* Combustion of liquid petroleum fuels (kerosine, diesel oil, or No. 2 fuel oil) with gaseous oxygen in the burner chamber at pressures of 100 to 200 psi results in temperatures of about 4300°F. Expansion of the hot combustion gases through divergent nozzles produces high-temperature supersonic jets having measured velocities of about 6000 fps. Impinging the flame jets on rock causes a thin surface layer to expand and break away from the base as a result of the thermally induced stresses. This spalling action is aided further in chert and quartzite by the 0.82 pct volume change resulting from the 6 to p quartz inversion at 1066"F.t The dynamic action of the jets whisks the spalled rock

Jan 1, 1952

By Edward D. Thimons

The Bureau of Mines conducted a state-of-the-art study of techniques currently employed to close large openings in underground mines. A large opening was considered to be any opening over 10 feet high and having a cross section of at least 200 square feet. Five salt mines and one limestone mine were visited to observe various methods of sealing large openings. Because of the variations in conditions from mine to mine, no definite conclusions could be drawn as to which is the best method. In mines where waste material is available, stoppings built by piling waste material are efficient and economical. Where waste material is not available properly constructed brattice cloth stoppings are superior to those built from wood, concrete block, or urethane foams.

Jan 1, 1975

By J. F. Papp

The microstructures of a CF2Br2-inhibited methane flame and its uninhibited analog have been determined using molecular beam-mass spectrometry. The slightly lean flames were stabilized on a cooled porous plug burner at reduced pressure. Composition profiles of stable, intermediate, and radical species and temperature profiles were obtained. Comparisons of the uninhibited and inhibited flame profiles revealed the following inhibition effects; a shift of the primary reaction zone to higher temperatures, a higher maximum flame temperature, an increase in the CH3 concentration, and a reduction in the H2CO, H, 0, and OH concentrations. Kinetic analyses of the data yielded rate coefficients at flame temperatures for the reactions H + CH4 ? CH3 + H2, H + O2 ? OH + O, CO + OH ? CO2 + H, and CH3 + O ? H2CO + H. CF2Br2 is judged to decay by thermal decomposition and abstraction reactions.

Jan 1, 1981

By T Barto, D Thomson, T Norgate, C Doblin

Collaboration between CSIRO Minerals and SunSalt Pty Ltd, a salt producing company located in rural Victoria, has resulted in a commercial process to recover magnesium sulfate (commonly called Epsom salt) from the saline waters of the Murray Basin. The feed for this process is bittern; the liquor remaining after halite (common salt) has been harvested from the saline water by evaporation.SunSalt produces salt and bitterns from three locations, namely Hattah (Victoria), Mourquong (NSW) and Wakool (NSW). The small size and considerable distances between these operations makes it uneconomic to build a stationary processing plant to extract value-added products, in particular Epsom salt, from the bitterns of the three operations. This fact led SunSalt to build a containerised mobile plant that could be moved to each site to process the bitterns at the end of the salt harvesting period.Epsom salt is extracted from the bittern by further evaporation, refrigeration and recrystallisation. In this process the bittern is diluted with five per cent volume of fresh water to minimise precipitation of residual halite in the bittern. Cooling the diluted bittern to between -5 and -10¦C precipitates up to 70 per cent of the magnesium sulfate, which is recovered as 85 to 96 per cent purity Epsom salt by filtration. This product is marketed as an industrial grade Epsom salt. Higher purity (up to 99.9 per cent) Epsom salt (USP or BP grade refined product) is made from the industrial grade product (raw Epsom salt) by recrystallisation.The containerised mobile plant was commissioned in December 2002. The raw Epsom salt generated in the mobile plant is refined to a higher purity Epsom salt in a separate plant located in Mildura. The Mildura plant was commissioned in December 2003.The CSIRO-SunSalt collaboration has demonstrated that the saline waters can be processed into a useful resource, and in addition could create jobs and a new skill base in regional Australia. The production of Epsom salt locally in Australia, which is worth currently about $A600 per tonne, removes the need to import over 3000 tpa from overseas with a net positive impact of $A2 million on the balance of trade.

Jan 1, 2004

By Yotamu Stephen Rainford Hara

"The aim of our work is to investigate a low energy and clean route for the recovery of copper and cobalt from complex sulphide mineral concentrates. The mineral concentrates were roasted in air, in the presence of CaO (MS + CaO + 202 =MO+ CaS04) at temperatures below 973K. The roasted products containing CuO, CoO and Fe203 were carbothermically reduced at 1073K within an hour to preferentially reduce copper and cobalt. The kinetics of reactions were studied using the thermogravimetric technique and by characterisation ofreaction products using the XRDSEM-EDX techniques. The effects of MS:CaO ratio, roasting temperatures and physical nature of the mineral concentrates were analysed. The method for capturing S02 by forming CaS04 was analysed for reuse in the process. The energy balance for the above process is compared with that of conventional continuous smelting/converting process.1.0 IntroductionCopper sulphide mineral concentrates from Zambia contains substantial amouot of cobalt. The cobalt metal content in the concentrates ranges between 0.7 and 2 % weight, which corresponds to 3 and 9 % weight copper, based on the spot price of copper ($7 386/tone) and cobalt ($31 000/tone). Although the traditional approach using a combination of roasting-leaching-electrowining steps can be applied to recover copper and cobalt from sulphide mineral concentrates [1-4], there are two major draw backs of the traditional process: (i) the S02 emitted during roasting is too lean for economical conversion for sulphuric acid manufacture, which causes serious environmental pollution. (ii) silver and gold which are normally present in the sulphide concentrates are lost out [5] because they are not leachable by H2S04 or HCl which are the common leachants. The above two problems have been overcome by adopting flash smelting in which a rich S02 gas above 20% is produced [1, 5] and successfully converted into sulphuric acid. The precious metals tend to partition to blister copper and recovered during refming. However, nearly all cobalt is lost into the slag phase uoder oxidising condition which prevails during flash smelting. It is important to note that the cobalt content in the slag can be up to 2.6 % weight [6]. The recovery of cobalt from the slag is a process which requires huge amouot of energy since the slag is smelted above 1873K [6]. With a view of minimising the amouot of energy and S02 emission during metal recovery, our investigation involves roasting the sulphide concentrates in the presence of lime and reducing the roasted samples with carbon."

Jan 1, 2013

By R. S. C. Smart

Surface chemical factors, including the balance of hydrophobic (e.g. collectors) and hydrophilic (e.g. oxidation products, precipitates) species, are major control determinants in flotation rates of specific minerals and therefore grade and recovery. There are a number of challenges involved with the surface analysis of different mineral phases from process streams in a flotation facility. The first is to collect samples that are representative of the process and retain their surface chemistry prior to introduction into the instrument. The second challenge in studying the surface chemistry of specific minerals is to find reliable methods of mineral phase recognition. In surface analysis of mineral particles, confident mineral selection can be difficult with many multi-metal minerals and with precipitated, adsorbed, reacted and contaminant species in the outermost molecular layers. The third challenge is to provide a statistical surface analysis of multiple grains of the same mineral. Methods to achieve these aims are described. Principal component analysis (PCA) of ToF-SIMS data provides improvement in phase recognition, particle selection and associated variations in surface species. Specific examples from both lab and plant operations, demonstrate that this technique can be utilized to differentiate surface chemical factors promoting (hydrophobic species) or inhibiting (hydrophilic species) flotation. A study of copper ion transfer (inadvertent activation) from chalcopyrite to pyrite and sphalerite clearly identified a statistical difference in copper intensities between the sphalerite and pyrite phases corresponding to their flotation response. The PCA analysis applied to concentrate and tails samples collected from the Inco Matte Concentrator demonstrated extensive CuOH and NiOH transfer between chalcocite and heazlewoodite minerals. The statistical analysis has been able to identify mechanisms controlling recovery and selectivity. High intensity conditioning (HIC) tests in which sphalerite was separated from a complex sulfide ore gave a 5% increase in the overall Zn recovery. The PCA/ToF-SIMS statistical analysis revealed the discriminating depressant action of adherent aluminosilicate (gangue) fine particles and adsorbed ions on the surface of sphalerite grains. HIC conditioning resulted in the removal of these gangue fines improving surface collector attachment efficiency.

Jan 1, 2014

By Sunil K. Tripathy

Particle characteristics such as size, density, liberation and magnetic susceptibility play vital role in magnetic separation technique. To understand the performance of magnetic separation process for chromite beneficiation industry, particle characteristics need to be analysed. However, to date, this has been an expensive and time consuming task, thus only minimal amounts of this type of data are available in the literature. Several new methods are being developed, that will produce the required mineralogical and liberation data to provide processing information rapidly and inexpensively. Among these, QEMSCAN is a unique and advanced characterisation equipment used for liberation analysis for different ore whereas S.G. Franz Isodynamic Separator for determining the magnetic susceptibility. In Indian chromite deposits, the content of iron bearing minerals in the ore is typical which controls the Cr:Fe ratio in the product while treating in gravity based beneficiation plant. In the present investigation, detailed characterisation of two distinct chromite ore samples from Sukinda chromite deposit, India, was investigated which includes advanced mineral characterisation using QEMSCANand magnetic susceptibility measurement by using Frantz Isodynamic separator, etc.. Presence of haematite and gibbsite along with chromite mineral were identified as major gangue minerals in the high grade ore from XRD pattern whereas Goethite, Quartz, Haematite, Kaolinite, Ringwoodite identified in the low grade ore. The mass magnetic susceptibility of low grade ore is very high 5.2 cm3/g compared to 2.7 cm3/g for high grade ore, due to the presence of abundant quantity of iron bearing minerals. Subsequently, these two types of ore were subjected for magnetic separation for improving Cr:Fe ratio by using different magnetic separators viz. induced roll magnetic separator, wet high intensity magnetic separator, rare earth roll magnetic separator, rare earth drum magnetic separator. The results of magnetic separation studies indicated that, Cr: Fe ratio of the chromite ores can be improved to 3.99 and 1.97 from the feed assaying 3.09 and 1.29 respectively. Studies on rare earth roll magnetic separator indicated that both the ores were upgraded to a maximum Cr:Fe ratio level at optimised condition. Keywords: characterization, QEMSCAN, magnetic separation, rare earth roll magnetic separator, industrial mineral, chromite

Sep 1, 2012

By T. H. Jeffers

The Bureau of Mines conducted laboratory tests to devise a procedure for extracting copper from low-grade discarded mill tailings. A solid extractant consisting of an organic solvent extraction reagent adsorbed on granular activated carbon was investigated and proved to be satisfactory for extracting copper directly from leach pulps. When this material was used in a cyclic leaching, stripping, and electrowinning pro-cess, 95 pct of the acid-soluble copper was recovered from oxidized mill tailings. The weathered tailings contained 0.24 pct Cu (total) and 0.20 pct acid-soluble Cu. The copper was recovered as cathodes containing, in parts per million, 1.6 Pb, 3.6 Fe, 0.5 Sb, 1.5 AI, 1.9 Mn, and <1 Mg.

Jan 1, 1985

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 T. P. Meloy

Traditionally the mineral and mining engineers have characterized particles by sieving and-settling. Within the last decade, with the advent of the scanning microscope, entirely new experimental and theoretical approachesl-10/have been taken to minutely define the particle surface. This approach depends upon a hypothesis which takes advantage of the recent developments in automatic micro-scopes which can acquire large amounts of information in a short time and the new computational techniques which rapidly reduce the information to meaningful, practical data. Historically sieving and settling are the oldest sizing techniques known. Sieving by square screens, shown on Figure l-A is a common, current practice for sizing particles both in the laboratory and in production. A woven cloth is used which usually has square openings. The size particle that will pass through the opening dependent on a complex relationship of its morphology. As can be seen in Figure l-A, neither the width nor the height of the particle is determined by sieving. From square screens one and only one parameter characterizing the particle size is obtained, that parameter is the radius of the sphere that will just pass through the given sieve opening. A variation of square mesh screen is the slot screens, shown in Figure 1-B. Here another measure more closely associated with the height of the particle is obtained. Once again, one and only one parameter is associated with the particles&apos; shape.

Jan 1, 1977

By P Ottenio, B CarrT

In the last 40 years, the froth flotation process widely spread in the paper industry becoming the dominant technology for ink removal from recovered paper slurries and cellulose fibres recovery. Most of current models used to describe the flotation deinking process are based on hydrodynamic and statistical theories of ink particles collision/attachment to air bubbles. The complexity of these theoretical models, together with the variability of the recovered papers composition, does not allow to define a set of æeasy to handleÆ equations to be used for modelling industrial flotation cells. This main limiting aspect makes that, in several deinking process modelling tools, basic parameters used to characterise the flotation unit, ie yield, ink removal efficiency, water loss, are constant parameters. Although in some process simulation tools the flotation yield/efficiency is adapted to process control parameters (air ratio, pulp flow, pulp consistency), physicochemical variables (namely the pulp frothing aptitude, the pulp surface tension and the ink adhesion energy to air bubbles) are not taken into account to adjust the flotation yield/efficiency. Data collected during recent laboratory and pilot plant experiments focusing on the role of surface active substances on the flotation efficiency were therefore interpreted and used to identify general trends that could be described with simple semi-empirical models. A set of model equations using surface tension and froth removal height as main variables was then defined in order to describe the behaviour of a pilot flotation cell. Trends obtained during the dynamic simulation of the deinking pilot plant were in good agreement with experimental data obtained under similar experimental conditions, thus indicating that developed equations can forecast with good approximation the behaviour of a flotation deinking unit.

Jan 1, 2005

By P. C. Benedict

"The Island Mountain mine is at the southeast end of Island mountain; across Jack of Clubs lake from the Cariboo Gold Quartz mine.; The orebodies consist of quartz veins and pyritic replacement deposits in limestone. To December 31; 1944; there has been mined 296; 273 tons of quartz-vein ore averaging about 0.34 oz. gold a ton; and 101; 002 tons of sulphide ore averaging about 0.83 oz. gold a ton; a total of 397; 275 tons averaging 0.46 oz. From this; 175; 985 fine oz. of gold and about 26; 450 fine oz. of silver were recovered; having a value of $6; 510; 521.More than 95 per cent of the production has come from a band 500 feet wide along the contact of the Rainbow and overlying Baker members and extending about 100 feet into the latter. Evidence that the Rainbow belongs stratigraphically above the Baker is presented later in this paper. Both members are most variable lithologically, and individual beds and whole series of beds pinch out in short distances. In part, at least, this is due to squeezing out incidentally to intense folding. No section can be claimed with assurance to be really representative. However, both memb.ers are composed predominantly of quartzitic rocks. Both contain argillaceous quartzite, argillite, limy quartzite, limy argillite, limestone (marble), and minor amounts of highly ankeritized rocks believed to be igneous sills possibly originally approaching diorite in composition."

Jan 1, 1954

By F Cesnik

The past few years has seen a concerted effort to improve the recovery of gold along with its co-product copper from the æhigh-gradeÆ Ridgeway concentrator at Newcrest Mining LtdÆs Cadia Valley Operations. A number of initiatives were identified and implemented, culminating in a sustained improvement in recovery of approximately three to four per cent for both metals. The key projects that contributed to this improvement included the installation of a 355 kW Metso stirred media detritor (SMD) to create a regrind circuit, installation of froth crowders on the scavenger circuit, installation of a Falcon SB2500SE gravity concentrator as part of the regrind circuit to improve gold recovered to bullion on-site and the optimisation of the grinding circuit to reduce the 80 per cent passing size (P80) of the primary grind from 160 to 121 ¦m for the same throughput via process control, cyclone and ball charge optimisation. This paper will focus on the supporting test work, where applicable, that was used as the design basis for the project, but more importantly the plant data before and after the changes to clearly identify the improvements to plant recovery.

Jan 1, 2007

By Y. R. Murthy, S. Angadi, A. K. Bhatnagar, S. K. Tripathy, L. O. Filippov

Dolomite is an essential raw material for the refractory industry, a flux in the iron and steel industry and also for the extraction of magnesium metal. Generally, particle size reduction, screening and classification are used for the preparation of the high-grade sized material for different applications, whereas low-grade fine fractions are not utilised. These fines or low-grade overburdens are dumped at the mine site for future utilisation, which creates environmental issues along with inadequate space management. In the present investigation, a detailed study was carried out to decrease the silica content of the low-grade dolomite fines from Gomardih , India, containing 28.6% CaO and 20.1% MgO along with 8.3% silica. Different process flow sheet options were evaluated with a combination of dry classifier, wet classifier, gravity concentrators as well as flotation. Different process variables were assessed along with mineralogical characterisation to optimise the process for efficient rejection of siliceous gangue minerals. Results indicated that dolomite, calcite and quartz are the major mineral phases present in the ore along with other minor minerals. It was concluded that two-stage flotation was an effective process for the reduction of silica up to below 1% after grinding to a particle size below 212 μm. A process flow sheet with a combination of gravitation air classifier and flotation can produce a concentrate with silica content below 4.5%. Keywords: Dolomite, flux, dry classification, flotation, characterisation, beneficiation

Jan 1, 2020

Major William R. Grunow, in a brief account off his military services, says: "I take pleasure in informing you that since my return from France I have been stationed at Camp A. A. Humphreys, Va., and am now on duty as a Senior Instructor at the Engineer Officers&apos; Training School. While in France, I served as a company commander in the 305th Engineers and was later ordered to return to the United States for assignment to new troops. Upon arrival in the United States, I received my majority." P. F. Rodegerdts gives us the following account of his military service: "I enlisted in the Naval Reserve Flying Corps in San Francisco on Feb. 12, 1918. On February 10, I was ordered to Cambridge, Mass., where I was enrolled for the course in technical aircraft construction given at Massachusetts Institute of Technology. After successfully completing the course of instruction, I spent six weeks in practical construction of seaplanes at the Curtiss aeroplane factory in Buffalo. Following this, I was assigned to active service at Akron, Ohio, on June 22, 1918. At the same time I received my commission of ensign U.S.N. R.F. Unfortunately, I have been kept at Akron and although I have made

Jan 1, 1919

By Ben Hogg

Since the development of the top-submerged lance (TSL) technology for copper and lead smelting by the cooperation of Mount Isa Mines (MIM), now owned by Glencore, and the Commonwealth Scientific Industrial Research Organisation (CSIRO) the core of the ISASMELT™technology has always resided in the lance system. Through continuous innovation and operation of our own smelters, first at MIM, subsequently at Mopani, and also at both the Kazzinc Copper and Kazzinc Lead smelters, Glencore Technology have expanded the core equipment supply to enhance the plant operability. The success of Glencore Technology’s expertise can be directly measured by the success of the Kansanshi Copper Smelter plant, which achieved 100% nameplate capacity within three months of start-up. This paper describes the ISASMELT™ core equipment and how it is applied to smelt sulfide materials. It highlights the strength of the ISASMELT™: continuous innovation to facilitate the versatility and continued increased capacity with every plant implementation.

By M. Yamine, R. J. Ring, D. J. Waters

"An experimental program has been carried out by the Australian Atomic Energy Commission to compare the effectiveness of Caro&apos;s acid as an alternative oxidant to pyrolusite in the leaching of uranium ores from the Alligator Rivers region of northern Australia. Batch leaching tests on Ranger, Nabarlek, Koongarra and Jabiluka ores showed that uranium extraction was unaffected by choice of oxidant, but that Caro&apos;s acid reduced acid requirements by 15 - 25%. Lime requirements for neutralization of tailings liquors were reduced by 20 - 30%.The batch studies were extended to a four-stage continuous leaching circuit with a capacity of 400 gore h-I. Comparative leaching tests confirmed the reagent savings obtained in the batch tests. Following these encouraging laboratory results, lnterox Chemicals Pty Ltd carried out plant trials using Caro&apos;s acid. Reagent savings in the mill were similar to, or better than, those obtained in laboratory test work. The trials also established that Caro&apos;s acid has a number of operational advantages over pyrolusite.IntroductionUranium is most commonly extracted from its ores by leaching in sulphuric acid. Simple hexavalent uranium oxides and compounds are readily soluble but uranium in the tetravalent form is insoluble and must be oxidized for dissolution to occur. The most commonly used oxidants have been sodium chlorate and manganese dioxide. They act indirectly by maintaining iron as the ferric ion which oxidizes uranium by a surface electro- chemical reaction. An Fe3+ concentration of about 1 - 2 g L-I is usually considered adequate for the effective dissolution of uraninite(1)."

Jan 1, 1984