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By Hiroyuki Sano, Hiroshi Chida, Katsuya Toda, Takafumi Sasaki

Saganoseki Smelter & Refinery is one of the largest copper producers in Japan to produce 450,000 tons of new copper annually. Saganoseki used to operate six PS converters with "4 Hot-2 Blow" scheme, but managed to change its operation to "3 Hot-2 Blow" scheme with four PS converters, while maintaining the same production capacity. To achieve the operational change, the following improvements have been carried out; 1) Extending service life from 220 to 350 batches, 2) Shortening cycle time by increasing the blowing rate and the matte grade, 3) Reducing environmental impact by applying sophisticated fugitive gas collection system and 4) Saving energy by waste heat boiler’s modifications. The operational change has been successfully executed, and results in drastic productivity increase and cost reduction. Currently, Saganoseki is maintaining the efficient and consistent operation with 4 PS converters. This paper describes the above-mentioned improvements for increasing productivity and the recent operational conditions of the PS converters.

Jan 1, 2015

"The Code was developed in 2004 through the Collaboration Agreement between Institution of Mining Engineers of Chile (IIMCh) and the Ministry of Mining (Chile) in Dec 2002. It is an amalgamation of current practices with respect to standards and procedures for exploration prospects, mineral resources, and reserves for the purpose of public reporting. Certification is required to prepare and issue information on mineral assets according to the guidelines that regulate the technical, economic, and environmental aspects that satisfy the conditions set by the Chilean capital and financial markets.The Mineral Resources Committee of the Instititution of Mining Engineers of Chile (IIMCh) is pleased to introduce theCode for the Certification of Exploration Prospects, Mineral Resources and Reserves which is the result of a Collaboration Agreement between the IIMCh and the Ministry of Mining established in December, 2002.This code synthetizes the present practice of the mining industry in regard to standards and procedures applied to exploration prospects, mineral resources, and reserves with the purpose of reporting publicly on financial instruments based on these mine assets in the capital markets. These standards follow general criteria already adopted and applied by capital markets in those countries characterized by a very dynamic and well developed mining sector such as Australia, Canada, Southafrica, United Kingdom, and others. The work done by the Mineral Resources Committee of the IIMCh has had the recognition of the Combined Reserves International Reporting Standards Committee (CRIRSCO) that leads the establishement of an international code in these matters. CRIRISCO is an entity formed by representatives of the countries previously mentioned, a representative of the Society of Mining Engineers of the UStates and a representative of the IIMCh. The Institution thanks the Ministry of Mining, the representatives of these Ministry in the Mineral Resources Committee, and specially the Minister of Mining, Sr. Alfonso Dulanto Rencoret due to the genuine support given to the IIMCh in the preparation of this Code.The Institution also thanks the Superintendencia de Valores y Seguros (SVS) because of the help given continuously to the Committee as well as by the interchange of opinions and suggestions received during the preparation of this document."

Jan 1, 2003

By Shamil Shaikhutdinov

CO adsorption on gold particles deposited on well-ordered alumina and various iron oxide films has been studied with temperature programmed desorption (TPD) and infrared reflection adsorption spectroscopy (IRAS). Structural characterization has been performed with scanning tunneling microscopy. Data show that the CO adsorption exhibits a size effect in that small particles adsorb CO more strongly. The effect generally vanishes after annealing to 500 K. For annealed samples, CO TPD and IRAS spectra are nearly independent of the particle size and supports studied. The results indicate that the CO interaction with gold surfaces is essentially similar and involves low coordinated atoms.

Oct 1, 2003

By A. Khodadadi, M. Abdolahi, P. Taimory

Cyanide is used by the mining and chemical industries in tremendous quantities without attention being given to its hazardous properties. The use of cyanide compounds in mining is one of the most important environmental issues for the mining industry due to the acutely toxic properties of many cyanide compounds to humans and aquatic life. Cyanide tends to react readily with most other chemical elements, producing a wide variety of toxic, cyanide-related compounds and because cyanide is carbon based an organic compound it reacts readily with other carbon-based matter, including living organisms. This research is aimed at investigating a feasible and economical technique for the removal of cyanide from tailing wastewater of Muteh gold mine. In this research, removal from Muteh factory's waste water, was achieved at Tarbiat Modares University's mineral processing laboratory through the oxidation of cyanide by calcium hypochlorite. Cyanide oxidizes and changes to cyanide (CNO-) which is 1000 times less environmentally hazards than cyanide. Cyanide titration was accomplished using Rhodanine solution and silver Nitrate. Cyanide concentration in the wastewater, was 270 mg/L. Cyanide removal was achieved at an optimum pH of 12.3. However, at higher temperatures, cyanide removal was complete at this pH level. Optimum Dosage for complete removal of cyanide using calcium hypochlorite was 1.43g/L.

Jan 1, 2005

By Robert B. Parsons

"Investors in flow-through shares are going to need an expanded road map to find their way through a growing maze of tax rules affecting such shares. At the end of 1985, no fewer than three new sets of important tax amendments were tabled which could have a significant effect on flow-through share issues. This proposed legislation is discussed this month in Tax Notes.IntroductionIn a flurry of legislative activity at the end of 1985, the federal government tabled legislation which includes the introduction of new rules which will have a notable effect on investors in flow-through shares and on companies that issue such shares.First, on November 26, 1985, Bill C-84, the legislation to implement most of the changes announced in the May budget, was introduced in Parliament. This legislation includes the rules for the $500,000 capital gains exemption, a matter of considerable interest to flow through share investors.Next, on December 2, 1985, the government tabled a Notice of Ways and Means Motion which would extend the time horizon for spending flow-through share funds to include the 60-day period following the calendar year. But all news was not good news. On December 4 the government released its proposals for a minimum personal income tax, which would include rules that would catch an investor's CEE expenses and capital gains."

Jan 1, 1986

By W. H. Stheeman

"The high rock pressures at the deeper levels of the Tsumeb Mine have necessitated the changing of the mining methods and the introduction of cable bolts. After two rockfalls in the cable-bolted stopes, the mechanics of cable bolting were investigated. Practical methods were developed to find the best grout mixtures, the bond stresses between cables and cement, the bond stresses between rock and cement and the load on the cable bolts, which was mathematically calculated from data observed underground. The design of the cable bolt support system as used at the Tsumeb Mine is explained. GeneralThe Tsumeb Mine is in northern South West Africa/Namibia, approximately 400 km by road from the capital city, Windhoek, at an elevation of 1300 m above sea level. Mining operations in Tsumeb were started in 1905 by the Otavi Minen und Eisenbahn Gesellschaft and continued, with an interruption during the Depre ssion, until 1940, when the mine was closed and taken over by the Custodian of Enemy Property. The present owner, Tsumeb Corporation Limited, obtained the mine in 1947 and restarted the underground mining operations in 1949 after the mine was dewatered. Currently, the stoping operations are between 26 Level (840 m below surface) and 38 Level (1260 m below surface). In addition, the mine is an important silver producer and has produced 670,100 kg of silver since 1947."

Jan 1, 1982

By J. R. Kadambi, E. Kucukal, J. Furlan

"Hydrocyclones are used in various industrial applications, including mineral processing and tailings management, to separate or classify solid particles and/or liquid droplets from multiphase feed. The fluid flow in a hydrocyclone (used in mineral processing) was investigated numerically and experimentally using particle-image velocimetry (PIV) and refractive index matching techniques. Two turbulence models were used in the calculations: the k–? model and the Reynolds stress model. Particle image velocimetry measurements were taken at various spatial locations along the cyclone. Computational results were validated globally using pressure and flow-rate readings at the boundaries, and locally by comparing the PIV velocity-vector maps and profiles.RÉSUMÉ On utilise les hydrocyclones dans diverses applications industrielles, dont la minéralurgie et la gestion des résidus, pour séparer les particules solides et/ou les gouttelettes liquides de l’alimentation polyphasée, ou pour les classifier. Une étude numérique et expérimentale sur l’écoulement des fluides dans un hydrocyclone (dont on se sert en minéralurgie) a été menée à l’aide des techniques de vélocimétrie par images de particules (PIV, de l’anglais particle image velocimetry) et d’appariement des indices de réfraction. Deux modèles de turbulence ont été utilisés dans ces calculs, à savoir le modèle de turbulence k–? et le modèle aux tensions de Reynolds (RSM, de l’anglais Reynolds stress model). La valeur de la PIV a été mesurée à diverses positions spatiales le long du cyclone. Les résultats de ces calculs ont été validés globalement à l’aide de relevés des pressions et du coefficient d’écoulement d’une extrémité à l’autre de l’hydrocyclone, et localement à des coordonnées spatiales spécifiques en comparant les cartes et les profils du vecteur vitesse PIV."

Jan 1, 2017

By C. P. Browning

Copper, as far as we know, was the first metal used by man, and due to the fact that it occurs in many places in the 'native' state, and also to the ease with which it may be shaped, it has played an important part in the evolution of civilization. Copper tools with inscriptions dating back to 6,000 B.C. are known in Egypt, where the metal probably got its start as a useful material in human hands. Just how far back the use of copper in Canada dates is difficult to say, but it was in use by the Indians in the Lake Superior country long before the arrival of the first white man. For many generations the Eskimos also have used copper derived fr0m deposits of the native metal found in the Coronation Gulf district. Due to the metal's many unique qualities, imperishable with age, ancient implements and utensils are apparently as good today as when they were made, having withstood the onslaught of time probably better than objects of any of the other base metals. Copper alloys so well with other metals that today it is second only to iron in its industrial value. Even at the beginning of the eighteenth century the world's production of copper was probably not more than seven thousand tons a year, with Great Britain producing three-fourths of this. One hundred years ago the mines of the United States, Chili, Mexico, Canada, South Africa, Australia, and Tasmania, which now produce about nine-tenths of the copper of the world, were totally undeveloped. Ln 1926 the world production of copper was approximately 1,658,000 tons, which was seventy thousand tons greater than in the preceding year; but growing demand absorbed the increased production, so that the stock of rough copper throughout the world is comparatively small. Of this huge tonnage of the metal, Canada produced four percent, two-thirds of it emanating from British Columbia, nearly one-third from the Province of Ontario, and the balance from Quebec.

Jan 1, 1927

By J. M. Cooper

The HBMS reverb furnace in Flin Flon was originally designed in the late 1920s. Throughout the decades campaign life has been increased due to operational practices, technological changes and brick quality improvements. In recent decades the campaign life had been extended such that a complete rebuild was scheduled every 3 years. The latest furnace rebuild and start up has been after a campaign life of nearly 6 years. Brick construction methods and techniques along with furnace operational practices allow the present campaign to be double that of the historical campaign length.

Jan 1, 2007

By A. J. Rigby

The wear mechanisms of the tuyere lines of Peirce-Smith and Hoboken converters are a subject of endless debate and speculation. However, there has been an indication that one of the primary factors in the deterioration of tuyere lines is due to the batch operation of the converting process. The cooling of the brick in the tuyere line during out-of-stack times leads to shrinkage of the brick and resultant opening of the joints. Subsequently, on re-entry of the tuyere line into the bath, the joints become penetrated with matte and re- expansion of the brick is prevented. It is thought that this regular cycle of exiting the batch for slag skimming and replenishment of matte and re-entering for further blowing leads to a gradual “ratcheting” of the tuyere brick lining. If no expansion allowance is furnished between the endplate and the endwall of the lining, then the generation of damaging compressive stress is unavoidable. INTRODUCTION It is generally accepted industry-wide that the integrity of a refractory lined vessel is determined by an inextricable combination of refractory brick quality, the caliber of the lining design and installation, and the severity of the process inflicted upon the high wear areas of the vessel lining. Rigby has summarized the concentrated attempt, over the past several years, to optimize the microstructural, chemical, and fracture properties of the refractories used in non-ferrous pyrometallurgical vessels. Furthermore, lining design concepts involving larger and longer brick and the extent and positioning of expansion allowance in the joints have been extensively trialed. All these efforts have provided some, but not startling, improvements. The simple fact is that a vessel lining composed of bricks with an optimized microstructure and chemical inertness must installed with a well-conceived design to decompress the lining stresses that are generated by the batch operation of copper converters. REFRACTORY QUALITY Converting is conducted by injecting air into the molten matte and white metal for the very purpose of generating iron and copper oxide slags. These slags must be contained by a refractory which, by its mineralogical formulation, is optimized for chemical inertness.

Jan 1, 2019

By Eamonn F. Maher

Superconductivity is one of the most remarkable scientific phenomena ever investigated. It is the phenomenon whereby some materials exhibit zero resistance to the passage of an electric current when cooled to low temperatures, and requires a quantum mechanical explanation. Four Nobel prizes in physics have been awarded specifically on the subject of superconductivity, with many more enabled by superconducting technology. For example, particle beams are generated in accelerators and manipulated in ?particle beam lines? in the ?Big Physics? projects around the world eg. at CERN, Geneva, leading to major discoveries in fundamental particle physics. Similarly, at the JET Propulsion laboratory near Oxford, U.K, controlled nuclear fusion has been demonstrated, and magnetic containment of plasmas is key. In the chemical and biological sciences high field NMR spectroscopy has become indispensable for examining organic matter, revealing the mysteries of the workings of cells, genetics, and in the development of new polymers and pharmaceuticals. With all these very advanced uses for superconducting magnets, it is easy to forget that superconductivity is big business, not just a scientific curiosity. MRI (Magnetic Resonance Imaging) superconducting magnets, the key component of high resolution body scanners, use approximately half of the world?s superconducting wire ? the other half being mostly used in accelerator magnets. The MRI market is about 3 billion dollars per annum, and one MRI magnet uses 200km of wire. New applications for superconducting magnets are now appearing including ?Catheter steering?, enabling much shorter timescales for life-saving brain tumour removals and ?Functional MRI?, a whole new area in patient diagnostics. Whilst the use of low temperature superconductors (LTS) is now well established commercially in superconducting magnets and niche electronic applications, the application of LTS in electric power distribution and transport has been very limited to date. It is now more than fifteen years since the so-called High Temperature Superconductor (HTS) materials were discovered: these can be operated at liquid nitrogen temperatures rather than liquid helium temperatures. However, materials processing and scale-up issues have prevented their widespread use, and in particular the required price/performance criteria are only beginning to be reached except in certain niche markets. BSCCO (Bismuth Strontium Calcium Copper Oxide) tapes up to one km long are now readily available, and have been demonstrated in high current cables for power distribution networks, but the general consensus is that 1) it is difficult to reduce the price much further because of the silver matrix required and 2) in applications where coils are required eg. motors, generators, transformers etc the properties of BSCCO are rather poor because of the critical current dependence on magnetic field. Magnetic fields are always associated with coils and windings, and such fields are of course fundamental to the operation of all electrical machines. YBCO (Yttrium Barium Copper Oxide) however, has good characteristics in field and for the last few years there has been intensive research and development costing several tens of millions of dollars worldwide into the scale-up of production of so-called ?coated conductor?. This ?second generation? tape can be produced by any of many different film deposition techniques, with more or less success for short lengths, but as yet it is unavailable in lengths more than a few tens of metres.

Oct 1, 2003

By R. A. L. Drew, G. Mendoza-Suarez, J. Filipi, R. Vintila, J. A. Kozinski

Economics and environmental considerations along with the increasing demand of hydrogen encourage development of novel technologies such as plasma processing of hydrocarbons and thermal cracking of natural gas. Plasma discharges, either in thermal or non-thermal regimes are expected to allow low temperature and fuel flexible on-site hydrogen generation. The main drawback of thermal plasma reformers is the high-energy consumption resulting from high-temperature operation. On the other hand, non-thermal plasma, generated by dielectric barrier discharge (DBD), is able to simulate the chemical reactions employing much lower energies than those required by thermal treatment processes. The non-thermal plasma process allows for instance, a direct conversion of methane into hydrogen and carbon black with no CO2 release. The focus of this research was on the GHG-free method of H2 generation in compact non-thermal plasma reactors using low, medium and high permittivity dielectric ceramics. A stable, non-thermal plasma was generated by placing a dielectric ceramic between two electrodes with a 25 thou gap and applying an alternating current of 1-5kHz and voltages of 4-8kV. In order to ensure energetic efficient plasmas, experiments were conducted to analyze the behaviour of different permittivity ceramics. It was found that the dielectric properties of a ceramic, when used in a DBD reactor, have a strong influence on the discharge characteristics, which in turn influence the power consumption. Higher dielectric constant resulted in higher conversion rates of methane (higher yield of hydrogen and carbon). At the same time, the mechanical properties of the dielectric material, which are closely associated with its processability, influenced its resistance to electron bombardment, as well as thermal and mechanical damage. Therefore a reliable ceramic should have good dielectric properties, in addition to good thermo-mechanical stability.

Jan 1, 2004

By Mark Sherman, M. Dennis, Raj Rajamani

"The two Alumbrera 36ft (10.97m)dia. SAG mills were sized, using the FDW ""Grindpower 'I program, to treat an average of 1852 tph each. This paper describes how modelling of the shell lifter design, using the Millsoft program, identified milling inefficiencies caused by poor charge motion. This explained the ""as built"" circuit's inability to achieve the throughput rates predcted by the circuit's designer. Use of the Millsoft program to design a new, dramatically different lifter configuration, in conjunction with a different approach to variable speed drive utilization, has resulted in an improved charge motion and a 30% increase in hard ore milling rates. The new lifter design has allowed the designer's predicted average throughput rates to be achieved.IntroductionThe Alumbrera project grinding circuit consists of two 36ft dia. X 17ft EGL, 13 500 kW, variable speed, gearless drive SAG mills coupled to four 20ft dia. X 30ft EGL, 6 000 kW fixed speed, gear driven, ball mills. The circuit is configured as two identical grinding aisles, each consisting of one SAG mill and two ball mills. No pebble crushing circuit was installed due to the expected absence of a critical size fraction in the first years of production. However, the grinding circuit layout does incorporate space for a pebble crushing retrofit. At present, only about 5% - 10% of the new mill feed reports as trommel oversize and is recycled back to each SAG mill using a water cannon.The circuit was designed to be ball mill limited and to treat the four major Alumbrera ore types at rates varying between 68 000 tpd, and 89 750 tpd, depending on ore hardness. Average throughput rate, and hence nominal design rate, for the grinding circuit was 80 000 tpd (1 852tph per line at 90% availability)."

Jan 1, 1999

By Rakesh Kumar, Rajabrahma K., A. K. Verma, V. Mukesh

"In this study, laboratory investigation as well as numerical investigation is carried out to ascertain the transition from one mode to another for Semi-circular bend setup. Laboratory investigation is carried by varying the span length (s/2R); crack length (a/R); notch angle (a); and notch thickness (t). The specimen consists of cement, sand and water mixture in a ratio of 1:1:0.5 by weight and are prepared as per the ISRM standards (2014). Tests are conducted by a servo controlled universal testing machine at a strain rate of 0.2 mm/ min. The results are collected in terms of failure load, crack mouth opening displacement (CMOD) and images of crack initiation and propagation.Image analysis of laboratory tested samples shows that crack initiates at the notch tip when the notch inclination angle is 0°. As the notch angle increases (i.e. 30° and 60°) the fracture begins to initiate behind the notch tip. The direction of crack propagation in front and back side of the sample is same for notch inclination angle is 0° whereas it differs more and more as crack inclination increases. The transition represents the change in mode of failure from mode I (0°), mode II (30°) and mixed mode I/II fracture (60°).Finite element method used to find the transition based on MTS failure criterion. The inclination of notch is varied like 40, 42, 44, 45, and 50 deg and FEM analysis shows that the transition from mode-I to Mode-II take place at 49 deg. The same procedure can be extended to find the transition from mode-II to mode-III."

Jan 1, 2015

By Sebastian Siebert

Unmanned Aerial Vehicles (UAV) as a data acquisition platform and as a measurement instrument have become attractive for many surveying applications in civil engineering. However, their performance is not well understood for these particular applications. The specific scope of the presented work is the performance evaluation of a UAV system that was built to rapidly acquire mobile 3D mapping data for large earthmoving construction sites. Details to the components of the developed system (hardware and control software) are explained. A novel program for photogrammetric flight planning and its execution for the generation of 3D point clouds from digital mobile images is explained. A performance model for estimating the position error was developed and tested in several realistic construction environments. Results to these tests are presented as they relate in particular to large excavation and earth moving construction sites. Results and experiences with the developed UAV system are in particular useful for researchers or practitioners in need for successfully adapting UAV technology for their application(s).

Aug 1, 2013

By M. Hozayen, Q. Ni, E. S. Radwan, P. Nawrocki, A. Jebbouri

"A major geomechanical study was conducted for one of the UAE onshore oil fields with the purpose of studying reservoir rock properties and stress distribution, based on which a 3D coupled reservoir geomechanical model was built. This model was later used for wellbore stability analysis and for analyzing the effect of fractures on future reservoir production performance, including fracture deformation and permeability evolution occurring due to reservoir depletion and resulting changes in local stress field. The subject of this study was a complex fractured Upper Cretaceous carbonate reservoir characterized by high degree of heterogeneity, both vertically and laterally. Wellbore instability related drilling problems were encountered while drilling the wells in this field. The problems were mainly in drilling the horizontal wells, including breakouts and mud losses. Experimental results of laboratory tests used in this study are summarized in Part I of this paper whereas wellbore stability analysis and formulation of a3D geomechanical model that was built for that purpose is summarized herein.A 3D geomechanical reservoir model was developed, which included natural fractures. The mechanical properties of the reservoir rock, such as Young’s modulus, Poisson’s ratio, UCS, friction angle and tensile strength were populated based on the correlations established in Part I of this paper and the developed model was then used to simulate the 3D mechanical-property distribution and the evolution of the in situ stresses in the field due to depletion from 1983 to present-day. Based on the full field model, mud weight cubes were developed to predict the safe mud weight windows in different drilling directions. In addition, well stability prediction for two planned wells was performed using a 3D near-borehole model. Firstly, the computed stress state and mechanical properties simulated in the full field model were extracted along the well trajectory of an existing horizontal well which was drilled recently and then, a3D near-borehole model was constructed along the well trajectory. The wellbore stability analysis along the well trajectory, including stress state, strain distribution and displacements, was performed to identify the instability events along the well trajectory. It has been seen that the presence of natural fractures is closely related to the recorded borehole instability incidents. The computed plastic strains which indicate the wellbore failure were consistent with the recorded wellbore instability events in the FMI image logs, what provide further verification of the developed model. Then, this 3D near-borehole model was applied to two planned horizontal wells and the wellbore stability analysis for the two wells was carried out.The results showed that drilling vertically in the reservoir is safer than drilling horizontally. However, the drilling mud weight window in the vertical direction is narrow, being as narrow as 18.7 pcf or 0.299 sg locally. Drilling horizontally is less stable towards the maximum far field stress direction than towards the minimum far field stress direction. The mud weight cubes were used to identify the optimal well placement and well trajectory. For planned well trajectories, this technology can also be used to determine the optimal mud weight."

Jan 1, 2015

By Timo Heikkinen

We have read, with great interest, Mr. Crocker's article on "Recent Trends in Autogenous Grinding," published in the October issue of The Canadian Mining and Metallurgical Bulletin. Referring to our paper, "Two-Stage Autogenous Grinding Investigations at Outokumpu," we can now report that last August we changed to this method at the Keretti concentrator. Prior to the conversion, the Keretti plant (see flow-sheet, Figure 1) had two primary rod mills, 6 ft. in diameter and 12ft. in length, in open circuit, followed by four secondary 9-by 12-ft. pebble grate mills in closed circuit with rake classifiers. Last summer, wl1en the Since August, grinding has been successfully carried out autogenously in two stages, with two mills being employed in the primary stage and four in the secondary. The size of the pebbles in the secondary mills is about the same as earlier -l V: i to 3 inches (Figures 4 and 5). Also, we generally prefer two-stage grinding to single-stage grinding because, in the former,

Jan 1, 1964

By H. J. Hartjens

"With the trend towards bringing into production ore bodies of lower and lower copper content every possible avenue of approach to achieve maximum copper metal recovery and keep milling costs to a minimum are of increasing importance.Equipment manufacturers have contributed a great deal by designing larger mills, flotation machines, pumps, etc. in lowering capital and operating costs; instrumentation and automation usually as a joint effort of operating staffs and equipment manufacturers have resulted in lower operating costs and improved metallurgy. Likewise manufacturers of chemicals used in mineral beneficiation have directed their research and development at new flotation reagents and treatment schemes to complement the needs for more efficient products, permitting coarser grinds without detriment to recovery, higher flotation rates, higher degrees of selectivity, as well as chemicals to improve settling, clarification and filtration. The various treatment schemes in use and suggested for consideration are:1) The choice of the flotation treatment scheme is largely dictated by the desire to operate a simple circuit, originally consisting of rougher and scavenger flotation, with scavenger concentrate either returning to the head of the rougher circuit or joining the rougher concentrate for cleaning by reflotation, with and without prior regrinding. The cleaner tailing was also recycled to the head of the rougher circuit. In the case of porphyry copper ores, this was originally the standard circuit. Lime is the preferred alkalinity regulator to adjust pH, usually in the range 10-12.To avoid the undesirable effects of circulating loads and gain the advantage of simplified control of the rougher circuit, open circuit cleaning is practiced more and more. In this scheme, cleaner tailing is scavenged to produce a discardable tailing and the scavenger concentrate returned either to the cleaner or the regrind circuit."

Jan 1, 1970

By R. T. Saxon

Prior to November 1975 there were several failures of front -wheel spindles on large haulage truck s in B.C., attributed to fatigue cracks. Since that time, a non-destructive test program has succeeded in detecting the cracks before catastrophic failure, However, the author regards the failures as just one example of a. general unreliability in large high-strength steel castings and urges the industry to look to forgings for sensitive components of heavy equipment.

Jan 1, 1977

By James R. Hein, Jane Reid, Robert W. Embley, Se-Won Chang, Randolph A. Koski

"Abstract - This is the first reported occurrence of an active hydrothermal field in an oceanic fracture zone setting. The hydrothermal field occurs in a pull-apart basin within the Blanco Fracture Zone (BFZ), which has four distinct mineral deposit types: (1) barite mounds and chimneys, (2) barite stockwork breccia, (3) silica-barite beds, and (4) silica, barite, and Fe-Mn oxyhydroxide in sediments. All deposit types contain minor amounts of sulfides. In barite stockwork, silica-barite beds, and mineralized sediment, Ba, Pb, Ag, S, Au, Zn, Cu, Hg, Tl, As, Mo, Sb, U, Cd, and Cu are enriched relative to unmineralized rocks and sediments of the BFZ. Fe and Mn are not enriched in the barite stockwork or silica-barite beds, but along with P, Co, and Mg are enriched in the mineralized sediments. Silver contents in deposits of the hydrothermal field range up to 86 ppm, gold to 0.7 ppm, zinc to 3.2%, copper to 0.8%, and barium to 22%.Mineralization occurred by diffuse, low to intermediate temperature (mostly <250°C) discharge of hydrothermal fluids through pillow lavas and ponds of mixed volcaniclastic and biosiliceous sediments. Bacterial mats were mineralized by silica, barite, and minor Fe hydroxides, or less commonly, by Mn oxyhydroxides. Pervasive mineralization of bacterial mats resulted in formation of silica- barite beds. Silica precipitated from hydrothermal fluids by conductive cooling and mixing with seawater. Sulfate, U, and rare earth elements (REEs) in barite were derived from seawater, whereas the REE content of hydrothermal silica deposits and mineralized sediments is associated with the aluminosilicate detrital fraction. Fe-, Zn-, Cu-, Pb-, and Hg-sulfide minerals, Ba in barite, and Eu in all mineralized deposits were derived from hydrothermal fluids. Manganese oxides and associated elements (Co, Sb, Mo, W, Cl, and Cu) and Fe oxides and associated elements (Be, B, P, and Mo) precipitated as the result of mixing of hydrothermal fluids with seawater."

Jan 1, 1999