Search Documents

By Bradley Stoughton

It is very easy to reduce iron ore at a temperature well below its melting point and produce a more-or-less-pure metal which can be used directly for implements, tools, or machines. This simplicity has been the cause of much money loss by persons who were so satisfied with the successful operation of a process that they paid all too little attention to the commercial aspects of it. How easy a direct process is may be gleaned from the fact that it was practised with some -success by primitive man, and has been in almost continuous operation in one form or another for a period of probably 4,000 years. The production of steel in ton lots, beginning about 1860, brought a new phase into the economic situation, which, however, had been already greatly modified in 1784 by Henry Cort's invention of purifying pig iron. Direct processes survived both of these revolutions, under special geographical conditions, even up to the last few years of the nineteenth century, but ceased to have any general use as the basis of supply for structural, machine, or tool industries even in countries which could have manufactured iron by a direct process, but, instead, imported the product of established iron and steel processes. And this is still the situation today, notwithstanding the invention of an incredible number of 'new' processes since 1900, most of which are abandoned, and only survived as along as their financial backers were willing and able to Jose money. Probably none of these processes failed to work pretty well, and all seemed to show a handsome profit on paper.

Jan 1, 1930

By J. D. Robertson

An in situ water sampling device has been developed to measure biologically-available or “labile” metals in natural waters and effluents. The active mechanism involves the use of a polyacrylamide gel layer to quantitatively control metal transfer to a trace-metal-adsorbing, gel-imbedded resin. Because the resin only adsorbs free metal ions (the gel sampler methodology is a kinetic speciation technique), and because metal bioavailability is related to the free-ion activity, the device provides a direct measure of the biological-availability of metals in the environment sampled. The prototype consists of a layer of ion-permeable polyacrylamide gel which separates the solution to be sampled from an ion exchange resin. Because approximately 90% of the polyacrylamide gel is water, mass transport through the gel is diffusion-controlled, and is therefore well defined. Metal ions are rapidly bound by the resin, creating a steep concentration gradient in the gel. The amount of labile trace metal that accumulates on the resin can be related directly to the concentration of the metal in solution, the exposure time and the molecular diffusion coefficient of the labile species. In addition, the passive nature of this device affords it the potential to address many of the limitations presented by conventional sampling methods, such as sample contamination introduced during collection or filtration and changes in trace metal speciation prior to analysis. Laboratory studies and limited field trials indicate that the sampler behaves as anticipated and illustrate that biologically- available metal concentrations in many environments are a small fraction of the total concentrations and often significantly less than the dissolved concentration. The implications of this on regulatory criteria are discussed. Additional field trials and correlation with bioassays are currently underway.

Jan 1, 2000

By M. Reda

Because of the adverse environmental effect of Chromate, Molybdate ions had been investigated as replacement for Chromate and the results had shown not to be encouraging. Film deposited from peroxopolymolybdate (from reaction of Molybdenum meta, with excess Hydrogen Peroxide), are more robust than that deposited from molybdate solutions. This was shown to be due to higher fraction of Mo (IV) and Mo (V) that form from Mo (VI) in the peroxopolymolybdate deposited film than the film deposited from Molybdate solutions. The peroxopolymolybdate film contains 40% un-hydrated molybdic acid, tetraperoxodimolybdate and tetra peroxo tetra molybdate. The protective properties of peroxopolymolybdate were shown to be due to the effectiveness of the un-hydrated molybdic acid.

Jan 1, 2010

By J. Baumbach, H. Bombach, M. Stelter

"Today technical electro-refining processes for copper exclusively use sulfuric acid, for silver refining nitric acid electrolytes are used. Sulfuric acid is characterized by very good chemical and electrochemical stability, good conductivity and low cost. The disadvantages of sulfuric acid are the precipitation of fine-grained cathodes with smooth surfaces only by using additives like glue, thiourea and chloride. In case of silver the electrolyte is electrochemical unstable and bears the risk of the formation of toxic NOx when pH is too low. A second disadvantage is the form of electrodeposition of silver as dendrites with their removal from the bottom of the Möbius cells.This paper reports the results concerning the application of an alternative electrolyte in copper and silver electro-refining. At first the electrolyte was characterized by the determination of current density potential curves. Electrolysis experiments were performed in laboratory scale using technical anodes for copper and synthetic anodes for silver. During the copper tests the solubility of contaminations from the anodes and the amount and chemical composition of the anode slimes were determined. Moreover the influence of current density, electrolyte temperature and the effect of several additives on the precipitation and chemical purity of the cathodes were investigated. In all experiments cell voltage as well as anodic and cathodic polarization was measured and current efficiency and specific energy consumption were calculated. A comparison with the results with those of tests using conventional sulfuric acid electrolyte shows the advantages and disadvantages of both systems, additionally the technical application chances and limitations for the new electrolyte. This electrolyte enables the precipitation of smooth copper cathodes with low silver and sulfur concentrations even at lower temperatures without any additive. For silver refining the electrodeposition of compact silver sheets is possible, that can be stripped comparable to those in copper electro-refining."

Jan 1, 2016

By J. Guha, R. Kanwar, G. Archambault, A. Tremblay

The Copper Rand Cu-Au deposit lies within a shear zone which strikes N50-60W and dips steeply southward (50°-55°) and extends over 1. 5 km with a thickness which varies form 350 to 425 metres. Mineralization, inside the shear zone, is structurally controlled by a dilation mechanism which can be explained by a fracture dilatancy model. The principle of this model involves the mechanics of overriding of irregular planes and surfaces of faults and schistosities, These structures are characteristic features of the Copper Rand shear zone. A structural analysis of the shear zone has been carried out to establish relations between the different structures within the shear zone and their evolution with the development of the shear zone. A geomechanical interpretation of the Copper Rand shear zone explains the formation of internal structures such as faults, schistosities and microstructure during the shearing. This interpretation confirms Ramsay's theoretical model on the geomechanical evolutuion of shear zone development, and the experimental work of Morgenstern-Tchalenko on the simulation of shear zones in clay models. The geomechanical interpretation of the shear zone demonstrates that at the onset, subsidiary fracture patterns are developed in second order faults in the following sequence. At peak strength Riedel shears ( R and R') are formed which propagate outside the strength, restraint (P) shears are developed in the thrust attitude within the shear zones. Principal displacement shears (D) develop toward residual strength in the direction of movement. Shear lenses are formed by the interaction of these shear discontinuities and these facilitate the formation of schis tosi ties with the continuation of the shear displacement within the main shear zone. While the main shear zone and the P and D shears within the main shear zone were in continual movement, the Rand R' structures, once formed, retained a simple fracture pattern and moved little outside the shear limits in comparison to the main shear zone. Parts of these structures inside the shear zone were reactivated by subsequent movements and deformed into folds to account for the present attitudes of the HW-1 and HW-2 and HW-3 structures. This geomechanical model for the shear zone with its subsidiary structures (R, R', P and D shears) is also applied on a larger scale to the Dore Lake shear belt and explains the different structures accompanying it. The initial development of the WNW shears (most are ore deposits) was followed by the subsidiary structures of the Dore Lake shear in a north-south stress field and is well defined by the movements characteristic of the different structures. It is concluded that the Dore Lake shear cannot be the prolongation of the McKenzie Narrows shear but it seems that this prolongation relates to the Henderson-Portage shear zone.

Jan 1, 1984

By Neville Jordison

Indirect, gravity flow, heat exchangers have become a well established technology in mineral and metallurgical process plants. The technology is a conventional heat exchanger using high efficiency plates, with a free flowing bulk solid on one side of the exchanger and a fluid on the other side. This simple concept leads to many opportunities for achieving greater energy efficiencies in process plants. Indirect heat exchange is much more efficient than direct heat exchange using air such as in a fluid bed or rotary device. When air is used directly, large fans are required, it may also be necessary to chill the air, both high consumers of energy. By contrast, using water as the cooling medium requires only low horsepower pumps, typically only 10% of fan HP. Furthermore there are no stack emissions with the requirement for removal of dust or emissions. Indirect heat exchange also creates the opportunity to recover energy. This can work in two ways: energy can be recovered from a hot bulk solid, to heat pressurized hot water for steam generation or preheat air. Alternatively recovered energy from elsewhere in the plant in the form of hot water, steam, air or thermal oil can be used to preheat a bulk solid.

Jan 1, 2011

By D. Want

In titanium-lined autoclave design the most critical point of its mechanical reliability is its titanium batten strips present at the circumferential and longitudinal barrel-weld seams. Recently an Australian Company, W.E. Smith Hudson (WESH) P/L, has developed a fully flush batten strip and is building autoclaves with this design. Significant research and development has been performed in the process. In this presentation, design aspects of these batten strips are presented that cover topics such as residual-stress magnitudes during fabrication, affect of preheat during batten-strip welding and residual stress in respect to fatigue life. There has been little research done regarding the affects of residual batten stress in relation to fatigue life. Considerations of this 'grey' area of design will be discussed based on the author's research data and finite element analysis.

Jan 1, 2005

By R. P. Charbonnier

"To understand the operation of jigs and other separating processes based on differences in gravity, it is desirable to analyse the motion of various particles in given media under specific conditions. A summary of the earlier theories shows that they lead to unsatisfactory or excessively complicated formulae in cases such as coal jigging. By adopting a simplified theory of the motion of particles in a fluid, the size and duration of the initial accelerated motion of a particle falling in hindered settling can be calculated. Based on this mathematical analysis, examples referring to actual coal jigging practice show that it is desirable to prolong and/or repeat, as frequently as possible, the optimum conditions corresponding to an effective acceleration of the particles. The separation is then obtained according to gravity rather than to particle dimensions, as would be the case if the velocity of the particles• were allowed to approach its terminal value. To achieve this gravity separation, it is suggested that the suction phase of the jigging cycle be artificially prolonged and the frequency of pulsations increased as much as possible for washing the coals of smaller sizes."

Jan 1, 1959

By J. Hall Carpenter

"Wet concentration has, in the history of ore dressing, been the primary treatment method following crushing, grinding and sizing, when these have been necessary. The evolution of new methods of gravity concentration has been comparatively slow.Today, the most significant and sophisticated of the new types of gravity concentrators is, no doubt, the cone concentrator developed by Ernst Reichert of Mineral Deposits Pty. Limited in Southport, Australia. These units have now had some years of use in the field, are becoming one of the standard tools of the industry and their metallurgical results, as outlined in this paper, are out-standing."

Jan 1, 1966

By Frank Mucciardi, Zhongsen Yuan

A new heat transfer technology --- termed Thermopump technology has been developed. This technology originates from conventional heat pipe configurations but has now evolved into its own class of heat transfer units, which we refer to as `Thermopumps (TP)'. A key feature is that Thermopump technology can be applied to high temperature / high heat flux environments where conventional heat pipe technology fails. Moreover, when implemented in less demanding applications where heat pipes appear to operate, Thermopump units have been found to function more smoothly and reliably. This paper will introduce Thermopump technology and several applications of this technology in steelmaking and refining will also be discussed. In addition, this paper will focus on three classes of applications: 1) waterless, non-consumable, high efficiency Thermopump oxygen lance and/or burner for EAF's, 2) Thermopump ladle lance for the desulfurization process, and 3) Thermopump cooling panels for furnace walls and roofs. Facilities equipped with Thermopump technology are expected to he better than the current corresponding ones in terms of increasing productivity and energy efficiency while at the same time lowering operating costs.

Jan 1, 2004

By Alex Matheson, Nick W. D. Massey, Peter T. Bobrowsky

Crowing pressures on aggregate resources include diminishing reserves, high transportation costs, sterilization and land use conflicts. In the absence of detailed resource knowledge for a particular region, aggregate resource potential maps provide the best "first approximation" regarding the surficial distribution of sand and gravel. The 1:50 000 scale Level Ill aggregate potential map integrates several important factors which influence the management of sand and gravel. Data used to generate this type of thematic map is readily available in most areas, fieldwork required is minimal, there is a logical quantitative evaluation of the data layers and integration is easily accomplished on a desktop PC-based platform. Also the aggregate potential map, with its focus on identifying areas of potential future aggregate exploitation as well as present inventory, provides a useful tool for the aggregate explorationist.

Jan 1, 2001

By T. F. Pugsley, D. Gignac

"The historical background to the project dates back to the mid-30s with the discovery of surface sulphide showings in the Cape Smith-Wakeham Bay ultramafic belt. In the mid1950s, orderly exploration commenced with an extensive work program by Asarco, INCO, Lemoine, Falconbridge and Raglan Nickel Mines Ltd. on exploration permits. In 1966, Falconbridge and Raglan Nickel Mines interests merged. Extensive exploration, drilling, under- ground delineation of the Donaldson orebody and the construction of basic infrastructure such as camps, airfield, road links from Douglas Harbour to Donaldson and Katinniq, a distance of 60 km, were completed.Production project design at that time consisted of plans for a 50 000 mt per year nickel mining and concentrating operation, including a 2000 person community and smelter at Douglas Harbour. These plans unravelled in the mid-70s due to high capital costs, poor nickel market conditions and the realization that the Raglan orebodies were not large enough to economically support the construction of green field smelter and refinery facilities for processing Raglan production. Nickel market conditions in the late 70s and early 80swere generally poor, resulting in further delays on production plans.While recognizing the very high potential to discover increased tonnages of high grade(3% Ni) in excess of 20 million tonnes, the project was deferred into the late 80s when a serious re-evaluation of exploration potential occurred and the requirement to prove up additional reserves resulted in an underground exploration program at Katinniq covering the period 1990-1992."

Jan 1, 1996

By C. Allen

In 2004, Boliden Odda underwent an extensive modernisation project targeting mainly the leaching section of the plant. Direct leach technology was introduced as part of this project. The Direct Leach process, developed by Outokumpu, is an atmospheric oxidative leach of zinc sulphide concentrate. The effects of this new processing operation on behaviour of iron in the plant are discussed. As well, the filterability of the new residue on belt filters prior to its deposition in mountain caverns is also discussed. The solids from the direct leach process have been analysed by scanning electron microscopy, and the results of these analyses are presented.

Jan 1, 2006

By Robert H. Clark

Introduction During the last twenty years, science and industry have been strenuously endeavouring to discover new sources and new kinds of liquid fuels and to work out suitable chemical methods for their production. One of the new possibilities for the production of liquid fuel on a large scale is law-temperature carbonization of various grades of coal. The use of alcohol as motor spirit, in spite of its relatively low calorific value, is being widely investigated. Its production by fermentation of sugars, its recovery from the sulphite liquors of the paper industry, its production directly from wood and also from calcium carbide, have all been considered. At present the most promising line of investigation would appear to be the further development of those technical processes which yield liquid fuels from coal; since science has shown the possibility of preparing all kinds of liquid fuels and even the complete conversion of coal into oils. The present paper will consider briefly: 1. The production of primary tar by low temperature carbonization of coal. 2. The hydrogenation of coal. 3. The synthetic processes of Dr. Franz Fischer.

Jan 1, 1928

By M. A. Hararah, T. Neesse, M. G. Farghaly, G. Proellss, P. Kaniut, W. Rubarth

ABSTRACT: This paper presents two new options for hydrocyclone control. Volume split control using a control valve in the overflow is applied for the stabilization of separation results at changing feed conditions. Controlled water injection to the conical part of the cyclone leads to the reduction of fine particles in the underflow. Hydrocyclone monitoring in both cases is performed by optical sensors that indicate the spray angle of the underflow. Applications in mineral processing for desliming, classification in closed-circuit grinding, and dewatering are demonstrated.

Jan 1, 2011

By T. Sun, J. Kou, C. Sun, China Railway Resources Group Limited

"The polymetallic sulfide ore in Jiama county of Tibet contains 0.78% Cu, 0.046% Mo, 0.31 g/t Au and 17.9 g/t Ag in average. However, heavy loss of valuable metals was observed using high-pH process and Butyl xanthate as the collector. In this paper, the flotation was optimized through the adoption of a novel collector C-7, which is a mixture of xanthate ester and thionocarbamate. This collector showed better flotation performance under weak base conditions. The recoveries of Cu, Mo, Au and Ag increased to 93.24%, 84.60%, 78.13% and 75.41%, respectively, under 15 g/t of C-7 at pH of 8.0. The adsorption mechanism of C-7 was investigated by micro-flotation tests, zeta potential measurements, FTIR analysis and adsorption quantity measurements. Chemisorption of C-7 on chalcopyrite surface is demonstrated with adsorption density 3.8 times higher than on pyrite.INTRODUCTIONXanthates are the most commonly used collectors of strong collecting ability for separating copper sulfide minerals from gangue in froth flotation. However, the selectivity of xanthates themselves is poor to realize separation of chalcopyrite and pyrite whose floatability are quite similar (Heyes & Trahar, 1977; Chandraprabha, Natarajan, & Modak, 2004). High pH process with xanthates as collectors is proved effective in copper-sulfur separation and is widely used in treatment of copper sulfide ore flotation (Smith, 1996; Valdivieso, Cervantes, Song, Cabrera, & Laskowski, 2004). This method could get ideal separation results, but large amount of lime must be added, and could bring about increased cost, device corrosion and environmental pollution. In addition, there could also be high depression and heavy loss of associated noble metal such as Mo, Au and Ag. Consequently, a large amount of research has been conducted on substitutions of xanthates for selective flotation of copper sulfide ores under low pH conditions (Gholivand, Khodadadian, & Ahmadi, 2010; Li, 2010)."

Jan 1, 2016

By H. Westengen

The AE alloy family exhibits remarkable combinations of properties when utilized as high pressure die castings. This performance relies on the fact that the rapid cooling rate resulting from the direct contact between the molten alloy and the steel die walls effectively refines the structure through rapid solidification. Furthermore, the rare earth additions modify the solidification pattern, dramatically reducing the solidification interval. A solid shell forms at temperatures exceeding 500C, reducing the tendency for die sticking and inverse segregation. As a result, the die castability is excellent, giving parts with a smooth and shiny surface. Unlike other magnesium die casting alloys developed to improve elevated temperature creep properties, AE alloys do not suffer from the commonly observed tendency to introduce brittleness. This feature is attributed to the fact that the massive magnesium- aluminium intermetallic phase is substituted by a finely dispersed lamellar structure of Al-RE intermetallics. The resulting combination of excellent elevated temperature properties and good ductility, as well as excellent corrosion resistance, means superiority of these alloys for demanding automotive engine and chassis applications.

Jan 1, 2006

By L. Tong

"The oxidation of Quebracho was evaluated by acid-butanol assay, which indicates depolymerization of Quebracho. Anthocyanidin, an oxidation product of Quebracho, is stable at 95?C for up to 2 h. The ionization, complexation, and oxidation properties of Quebracho were discussed. Complexation of metal-Quebracho occurs at ambient temperature. The formation of complex precipitates is influenced by the acidity of the solution. Temperature is another important parameter that influences the oxidation and the complexation of Quebracho. Quebracho-ferric complex precipitate forms at 90?C, 0.1 mol/L H2SO4. The formation of Quebracho-metal complex in the leach solution is a possible reason for the consumption of Quebracho. Quebracho molecules adsorption on the mineral surface is reduced by consumption of Quebracho, resulting in poor sulfur dispersing effect in the leaching process. INTRODUCTIONQuebracho is used as a sulfur dispersing agent (SDA) in the pressure leaching of zinc concentrate as stated in U.S. Patent No. 3,867,268 (1975). It prevents the zinc sulfide particles from being coated with molten sulfur, thus preventing the inhibition of the zinc leaching reaction. Recently, the sulfur dispersing effect of Quebracho was investigated in the oxygen pressure leaching of nickel concentrate. The oxygen pressure leaching of pentlandite can be represented by reactions 1-3."

Jan 1, 2012

By G E. Craig, W. M. Williams

A simple, easily constructed apparatus suitable for the zone refining of iron and other reactive materials is described. After eight passes at one inch per hour, the iron produced showed a marked drop in hardness to 49 Brinell. In addition, an arbitrarily -defined recrystallization temperature was lowered by about 35°C and the rate of grain growth greatly increased. CERTAIN materials, of which iron is one, are so reactive that they cannot be zone refined in any known container without becoming contaminated. For such substances, the floating zone method ( 1) may be used. In this method, the specimen is supported vertically in an inert atmosphere and the molten zone supports itself by its own sur-face tension. The method was first applied to silicon (2) and has since been used for other reactive metals such as zirconium and titanium. Smith and Rutherford (3) have previously reported on the floating zone refining of iron; the efficiency of the method for reducing the car-bon content was demonstrated on

Jan 1, 1962

By H. Lazreg

This paper presents an evaluation of surface resistivity techniques as a tool for delineating salt-water intrusion in Shippegan, N.B. The study consisted of resistivity profiling, resistivity soundings and a limited number of induced polarization soundings in selected areas in the Province of New Brunwick. The results from resistivity profiling indicate that when seawater intrusion occurs in a sandstone formation the resistivity contrast is sufficiently large to allow a precise delineation of the intrusion. A formula is then derived to convert resistivity values to chloride concentration in the "cone of intrusion". The results from resistivity soundings showed that shaly formations may have resistivities as low as seawater-contaminated sandstone. An indeterminacy has resulted from this resistivity overlap. A limited number of IP soundings were performed in an effort to resolve it. The results showed that IP can be of appreciable help in resistivity interpretation.

Jan 1, 1972