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By R. F. Hammen

Copper is one of the most widely used metals in industrial processes and is also present in most mining operations. Extraction of copper from solutions often proves difficult due to the presence of complexing agents. ChromatoChem, Inc. has developed a Solid Phase Extraction (SPE) support (HiPAC) for removal and recovery of metals from wastewater. The HiPAC SPE support employs chelating agents covalently coupled to a long linker molecule. Several solutions containing copper and complexing agents were tested including 1) copper and carbonate, pH 9.8, 2) mixed metals and anions with copper and cyanide, pH 11, and 3) copper and the chelating agent EDTA, pH 11. The copper was extracted from solutions one and two at high pH, but the EDTA containing solution needed the pH lowered to make the copper available for capture. In each example, the copper concentration was significantly reduced by HiPAC SPE treatment.

Jan 1, 1994

By J. P. Downey, T. Salisbury, M. Berlin, E. Rosenberg, G. Pinson, R. Christianson, K. Gleason, W. Gleason, S. Davis

"The Center for Advanced Mineral and Metallurgical Processing is developing membrane production technology based on autocatalytic reduction of palladium from solution onto a unique, porous substrate. Surface membranes and catalytic structures are critically important to applications that range from hydrogen purification membranes to petroleum refining. Autocatalytic reduction processes represent a cost effective method of producing stable surface layered structures that have good working lives. These attributes are particularly important in the production of palladium alloy purification membranes used in hydrogen production. Although considerable research has investigated the interaction of hydrogen and palladium alloys, the mechanisms in play while the membranes form are not well understood. Preliminary research has identified three distinct deposition mechanisms and it appears that substantial control over the resulting membrane is possible.IntroductionPalladium-based membranes separate hydrogen from other gases because hydrogen is uniquely soluble in and readily passes through bulk palladium. As currently produced, palladium-based membranes are expensive and have short service lives. These circumstances are due in part to the lack of a complete understanding of palladium or palladium alloy deposition. The Center for Advanced Mineral and Metallurgical Processes (CAMP), in collaboration with the Metallurgical and Materials Engineering Department at Montana Tech and the Chemistry Department at the University of Montana, is engaged in the development of new methods and materials for hydrogen purification membrane production.In membrane production, the palladium requirement depends on substrate surface properties such as surface chemistry, porosity, and roughness. Thin, defect-free membranes have been successfully produced on substrates of porous glass, alumina, and stainless steel. However, the differences in the thermal expansion coefficients of palladium membranes and porous glass or alumina substrates cause problems at operating temperatures. The use of stainless steel substrates is advantageous because stainless steels have thermal expansion coefficients similar to that of palladium and they are stable at the required operating temperatures (Wicke, E., Brodowsky, H. and Ziichner, H. ). Stainless steel is also readily available and relatively inexpensive."

Jan 1, 2012

By J. C. Agarwal

Do large-scale projects in mining and smelting start up and achieve expected capacity on schedule? In most cases not. Regardless of worldwide location, company know-how, or financial backing, unforeseen delays occur. A comprehensive CRA study for the World Bank shows that delays are the rule, not the exception, in most mining and smelting projects. When delays are not factored into analysis and planning, financial projections are, literally, not to be believed. Returns on investment will seldom achieve their targeted level because of startup delays. This paper reviews the results of our analysis of startup of new mines, mills, and smelters; provides a detailed discussion of why delays occur in the smelters and refineries; presents the cash flow implications of startup delays; and discusses preventive measures that should be taken to avoid financial shortfalls,

Jan 1, 1983

By Bhagyadhar Bhoi, Chitta Ranjan Mishra, Hara Prasanna Mishra

"In the Sukinda Valley of Orissa, India, the total quantity of nickel ore reserves comprising of both lateritic and chromite over burden(COB) have been estimated at around 231 million tonnes containing 0.3 to 0.9% Ni. While mining of one tonne of Chromite ore, around 6-7 tonnes of chromite over burden are removed. These overburden materials are disposed as waste materials, which causes lot of environmental hazards and ecological imbalance. India imports a large amount of nickel and ferro-nickel to meet its growing demands in various sectors. For import substitutions, efforts have been made to produced ferro-nickel from the lean deposits of nickel bearing lateritic ores/ chromite over burden materials by reduction roasting followed by magnetic separation and then the nickel rich magnetic fraction is smelted to produce ferro-nickel. It has been possible to produce ferro-nickel of grade varying from 4-25% nickel.IntroductionDuring mining of chromite ore, large quantities of overburden materials are being generated. The materials amount to approximately 10 million tones per year contain around 0.3-0.9% Ni, 0.02-0.06% Co, 20-50% Fe and 4-9% Cr2O3 depending upon the location and the depth of the mine. These materials presently do not find any application for the extraction of nickel due to lack of a suitable technology. The materials are also unsuitable for ferro-nickel making because of their very high iron to nickel ratio. The country is seriously looking for a suitable technology to utilize these resources as its entire domestic requirements of nickel is met though imports. In this connection, a systematic approach has been made at the Institute of Minerals and Materials Technology, Bhubaneswar to develop a process for ferro-nickel making from this indigenous resource."

Jan 1, 2011

By P. R. Taylor

Titanium carbide and titanium diboride powders have been successfully synthesized by direct treatment of ilmenite concentrates in a non-transferred arc thermal plasma reactor. Methane gas was used as the reducing agent and boron oxide was used as the boron source in these processes. Free energy minimization plots were used to predict the behavior of each system under different molar ratios and operating conditions. Products were characterized by XRD, SEM and chemical analytical techniques. The average size of the ceramic product is in the submicron range. Metallic iron apparently is finely deposited on the surface of the titanium carbide or titanium diboride particles. Minor impurities such as silica, manganese and zircon were converted to the carbide form.

Jan 1, 1995

By Norihiro Murayama

Syntheses of zeolitic materials were carried out from coal fly ash by alkali hydrothermal treatment as part of the reuse and recycle technologies of coal ash, For the obtained zeolites, the cation exchange capacity and acid resistance, which are very important in the practical use of cation exchanger in aqueous solution, are investigated during this stufY, The cation exchange amounts of the NaP, CaP and K-CHA zeolites are measured for various cations such as K+, Na +, NH4+ Ca2+, Mg2+, Pb2+, Cd2+ and so on. The change in crystallization degree are researched as a function of pH. The simultaneous removal ability of NH4+ and PO43- in solution is examined for an example of the water purification with CaP zeolite. From these results, the characteristic and its mechanism of cation exchange are clarified for the various zeolitic materials obtained from coal fly ash.

Jan 1, 2003

By T. -M. Guo, M. J. Braun

"This paper presents an experimental and numerical study of melt flow near the solid-liquid interface and its effect on the interface curvature in a horizontal unidirectional solidification system with succinonitrile. Melt flow is introduced by increasing the ampoule channel thickness. Visualization techniques are employed to observe the flow field and the solid-liquid interface curvature. A numerical model is also developed to simulate the heat transfer, melt flow and phase change in the system. Quantitative information on the flow and temperature fields is generated. A good agreement is achieved between the experimental observations and model predictions. The results could be used for the study of the effect of the melt flow on interface morphology during solidification.IntroductionClassic unidirectional solidification experiments of transparent alloys are conducted with thin film samples sandwiched between two glass slides to investigate the development of interface morphology during solidification [1]. Samples with small channel thickness are usually used to suppress any melt flow due to natural convection and solidification in the channel would then be in the diffusive regime so that the solidification theory can be significantly simplified [2, 3]. Effects of melt flow, in particular due to natural convection, on solidification have also been studied extensively in those systems with large geometrical dimensions [4-6]. These studies indicate a strong effect of the melt flow on interface curvature during solidification [5, 6]. Only limited efforts were made to address the effect of the melt flow on interface morphology in horizontal unidirectional solidification, in particular for the cases when the channel thickness is not thin enough to suppress completely the natural convection [7]."

Jan 1, 2004

By Hiroshi Nakajima, Kotobu Nagai, Toshihiro Hanamura

"Low carbon ferritic steel bars with ultra-fine grain structure was developed through a warm rolling for the first time by the present authors. They show better low temperature toughness than conventionally hot-rolled plates. Hence, the brittle fracture surfaces in Charpy tests were examined in terms of the effective grain size of fracture, compared with those of conventional QT steels. The ductile-to-brittle transition temperatures were in good accordance with those for the QT steels if referred to the effective grain size of fracture: · However, the size was a few times that of the ferrite grain. This means the grain refining is not yet fully utilized from the viewpoint of low temperature toughness. The anisotropy of· the impact properties and the annealing effect of highly dislocated structure on the toughness are also discussed in the present paper.IntroductionFor structural materials, both high strength and good toughness are required. Well-known approaches for obtaining better toughness for steels are as follows:1) Grain refining2) Addition of Ni3) Thin plate effect by cracking parallel to the rolling direction prior to crack propagation4) Contribution of metastable austenite.Among them, only the grain refining can raise the strength and improve the toughness. And it is well known that the finer the ferrite grain size, the lower the ductile-to-brittle transition temperature. For example, in the case of 0.11 carbon steel, the transition temperature decreases linearly to in d 1/2 [1 ]. However, these have been told in the regime of coarse grain size that is larger than 10 µm in diameter. There ~as .been no study dealing with the low temperature toughness in the regime of ultra-fine grain size with a diameter in the order of 1 µm."

Jan 1, 2000

By Bingliang Gao, Junli Xu, Michal Korenko, Jinzhao Guan, Liangxing Li, Zhongning Shi, Zhaowen Wang, Aimin Liu

Al-Si alloy, a precursor of solar grade silicon, was prepared by direct electrolysis in cryolite molten salt at 950 oC using high purity silica as material, liquid aluminum as the cathode and high purity graphite as the anode. The electrochemical behavior of Si(IV) ion was investigated using cyclic voltammetry method. The electrolysis products were characterized by XRD, SEM/EDS and ICP. The results indicate that the reduction process of Si(IV) on tungsten electrode is a two-step process and there is about 0.6 V gap between the two steps. The contents of boron and phosphorus in the aluminum-silicon alloy are 3 ppmw and 8 ppmw, which will make the directional solidification purification effectively and reduce the cost of preparation solar grade silicon from metallurgical grade silicon.

Jan 1, 2015

By Guangshi Li, Xionggang Lu, Xueliang Xie, Xingli Zou, Yuyang Bian, Hongwei Cheng, Kai Zheng, Changyuan Lu

The corrosion resistance and corroded microstructure of MgO-C refractory in molten slag are investigated by immersion test in muffle furnace at 1600 °C . The microstructure and chemical compositions of the specimens after erosion experiment are characterized by scanning electron microscope (SEM) and energy dispersive X-ray (EDX). The results confirm that the oxidation of graphite is the most important degradation mode of MgO-C refractory. The structure of the refractory material is damaged due to the decrease of graphite, as a result, the periclase substrate reacts with the molten slag directly. The corrosion process is controlled by the dissolution of the refractory materials into slag, low melting point oxides are therefore generated which lead to the damage of MgO-C refractory finally.

Jan 1, 2015

By Serdar Aksu, Fiona M. Doyle

"CMP will be an essential process in the production of integrated circuits containing copper interconnects. This study aims to improve our mechanistic understanding of the role that organic chelating agents might play in the reactive slurries used in copper CMP. Copper dissolution behavior in EDTA arid glycine was first examined by producing potential-pH diagrams for the copper-water-EDTA and copper-water-glycine 'systems. The results of potentiodynamic polarization experiments were then considered in light of these diagrams. . In-situ polarization experiments were conducted to gain insight into the electrochemistry of copper during dynamic polishing in slurries prepared from EDT A and glycine.IntroductionCopper has recently started to replace aluminum as the interconnect metal in integrated circuits. Copper interconnection offers faster and more reliable integrated circuits due to its higher electrical conductivity and superior electromigration resistance (1). The damascene method is used to form multilevel interconnects in the manufacture of integrated circuit devices with copper metallization (2, 3). Copper is deposited by CVD or electroplating into vias and trenches etched in the interlayer dielectric (IDL), over a diffusion barrier usually made from titanium, tantalum or their nitrides. Chemical mechanical planarization (CMP) then prepares the wafer for the next deposition step, by removing excess copper and planarizing the surface. During CMP, the wafer is rotated and pressed against a rotating platen covered with a polishing pad. Chemically active slurries containing submicron size abrasive particles (Si02, Al20 3, ceria, diamond, etc.) are applied. Both the mechanical action of the abrasive particles and the chemical action of slurry constituents remove material from the wafer surface. Planarization results because material is removed faster from protruding regions on the surface than from recessed regions. Since CMP can globally planarize .the entire wafer, it has become one of the key technologies for producing integrated circuits with copper metallization."

Jan 1, 2000

By Alain Jardy, Thibaut Quatravaux, Denis Ablitzer

"A numerical model of the Vacuum Arc Remelting process has been developed and applied to simulate remelting of various metallic materials, such as specialty steels, titanium and zirconium alloys. In practice, electromagnetic stirring is sometimes used, resulting in a complex 3D molten metal flow. After having validated the numerical model for different remelting conditions, we can use it to study the effect of applying a constant or alternated magnetic field on the thermohydrodynamic behaviour of the melt pool. The intensity of flow turbulence, computed with a classical k-E model, is shown to depend strongly on the nature of electromagnetic stirring.IntroductionThe principle of the Vacuum Arc Remelting (VAR) process, illustrated in figure I, consists in melting a consumable metallic electrode of the required grade under a high vacuum, in order to obtain a sound ingot of good structural quality.During remelting, an electric arc is maintained between the tip of the electrode and the top of the secondary ingot, in order to ensure melting of the electrode. The metal droplets fall through the arc plasma and progressively buid up the ingot, which solidifies in contact with the walls of a water-cooled copper crucible. The secondary ingot formed in this way contains three distinct zones, corresponding to the liquid pool, fully solidified metal and intermediate mushy zone. In order to stabilize the arc, it can be confined with the aid of a magnetic field created by an external induction coil. This field can also be used to stir the liquid metal, the rotation induced being in the orthoradial direction. By reversing periodically the coil current, stirring can be alternated."

Jan 1, 2004

By P. A. Botha

Most sinter producers prefer to use a range of iron ores with the aim to optimize their sinter blends. ISCOR is however limited to the use of ore from two deposits, namely Sishen and Thabazimbi. Only sinter produced from Sishen ore is described in this report. The Sishen iron ore deposit provides high-grade hematite ore with a mean iron content of 65 per cent. Three major ore types are developed: massive, laminated and conglomeratic. The main ore mineral is hematite with minor to trace amounts of quartz, mica, phosphates and, in places, carbonates. A sinter product is characterized by its mineralogical composition and metallurgical properties. The production rate also plays an important role in the economic evaluation of sinter quality. Sinter-pot tests were conducted with varying basicities, given as the ratio of CaO to SiO:< and coke content. The results of these tests were characterized by mineralogical and metallurgical methods. Basicity of a sinter mix directly influences the mineralogical composition and metallurgical properties. The content of calcium ferrite and calcium silicate increases with increasing basicity, thereby increasing the reducibility and cold strength of the sinter product. Experiments performed during this study provided a model for the optimization of the sinter mix with respect to its mineralogical and metallurgical parameters.

Jan 1, 1991

By B. Sereda

As it is known the creation and development of new titanic alloys has been problematic up to now. They can be used in aircraft and vehicle construction, shipbuilding and as materials for keeping static loadings in high-temperature environments. In this work the synthesis of various titan aluminides is investigated. Mathematical model of structurization process was done. On the base of retrieved model the mechanisms of structurization in systems Ti + Al and Ti + 3Al was determined. Experimental researches were done at two different modes: burning and thermal spontaneous ignition. The method of retrieving compacted products combusted in SHS conditions (SHS-compacting) was used to gain these intermetallic compounds. The physical and thermal characteristics of technological process and their influence on structurization, homogeneity of structure and porosity of titan aluminides have been simulated and researched. It is established that the SHS-compactizing technology is fully capable of supervising the process of structurizations with the whole complex of advantages and can be applied for receiving qualitative titan aluminides with the set of chemical-physical properties.

Jan 1, 2010

By Takashi Ikeda, Masafumi Maeda

"Demand for solar cells is increasing linearly throughout the world. Last year production totaled 3000 tons worldwide. The market size of solar silicon is expected to increase further because of international ""political"" demand to reduce carbonaceous emission from energy consumed. Most elemental silicon is produced by the carbon reduction of Silica in an electric arc furnace. Purity of silicon at this stage is 90-99%. Major impurities are Fe, Ti, Ca· and Al, and minor ones are P, B and carbon. The oxidizing metallurgical process is no longer effective to remove transitfon metals because those are less noble to silicon. Nonmetallic impurities such as phosphorus and boron must be reduced to 0.001ppm for semiconductor use. The most common process for high purity silicon is the Siemens C process, which is basically distillation of hydro-chlorinated silicon followed by CVD of SiHCl3. The cost of such silicon is expensive to allow its popular use in solar cells. Currently scrap silicon -of semiconductors is used for this; however, the supply-of that scrap is limited to just a portion of semiconductor production.In this paper world demand for silicon will be reviewed and some of the processes proposed summarized.IntroductionSilicon is element 14 in atomic number and has an atomic weight of 28.0855. Little elemental silicon is found in the earth, and it is mostly found as oxides or silicate. The Clark number of silicon is very large and the second in its number. If we were discussing the volatility of silicon element on the globe, we would never worry about it. However, it is very difficult to obtain pure elemental silicon because a high purity silicon compound is very rare. In most cases these are silica (silicon oxide SiO2). As shown in Table 1, there are many grades of silica ore classified mainly by their content of iron and alumina."

Jan 1, 2000

By Chuanlin Fan

The process of flotation separation and recycling of spent potlining (SPL) was described. On the basis of the laboratory investigations, the effects of influencing factors in froth flotation process, such as grain size, flotation agent dosage, pH value, pulp density, and dissolved components concentration, etc, were carefully studied. And the influence on environment of the process was also discussed. It was found that flotation separation can be used as an environment-friendly method for treatment of SPL residue. Carbon and other compounds (include cryolite, sodium fluoride, calcium fluoride and diaoyudaonite, etc.) from SPL were separated and recycled as flotation products respectively.

Jan 1, 2009

By Wei Yu, Tiejun Chun, Jian Pan, Deqing Zhu

In this paper, the technology of producing fluxed pellets by using hydrated lime as binder instead of bentonite was carried out. Green balls with 0.8% bentonite and others with 2% hydrated lime were obtained under the same conditions of 1.5% coke, 1.45 basicity and balling at 8.5% moisture for 13 min in disc pelletizer. The properties of two types green balls were as follows: drop numbers of 4.8 to 5.0 times/0.5m, compressive strength of 19.7 to 24.2 N/pellet and thermal shock temperature of 280 to 385?, respectively. Comparing with bentonite as binder, the compressive strength of fired pellets with hydrated lime is elevated by 13.8% and climbs up to 3113 N/pellet under the following conditions: preheating at 1050? for 10 min and firing at 1300? for 15 min. The hydrated lime also improves the metallurgical performance of fired pellets. The reduction index was enhanced from 68.6% to 70.6%, RDI+3.15 increased from 90.1% to 98.8% and reduction swelling index dropped from 22.4% to 7.4%, respectively. Therefore, hydrated lime can not only replace bentonite as binder to enhance the firing behaviors of green balls, but also effectively improve the metallurgical performance of fluxed pellets which can be used as high quality feed for blast furnace.

Jan 1, 2011

By Jilai Xue, Jun Zhu, Germain Kouma Ndong, Qiaochu Liu, Luxing Feng

"High-temperature oxidation and corrosion behaviors of Ni-Fe-Cr alloy as inert anodes for aluminum electrolysis have been studied in oxygen and molten electrolyte. The oxidation and corrosion scales on the anodes tested were analyzed using XRD and SEM-EDS. The oxidation rate is found to increase with increasing temperature from 700 °C to 950 °C, which can be approximately described by an inverse power rate function. The oxidation scales at 750 °C, 920 °C and 950 °C contain Cr-rich phase along with FeCr204 and (Feo.6Cro4)203. The corrosion extent of Ni-Fe-Cr anodes in electrolyte is dominated by temperature, which can make the scales thickness double from 700 °C to 750 °C or from 920 °C to 950 °C. Cr and Fe in the scales on the anode in electrolysis corrode preferentially into the molten electrolyte, while the nickel oxides could better sustain the corrosive environment in electrolysis. The results can be useful for developing inert anode material for potential application in aluminum electrolysis.IntroductionThe development of an inert anode for aluminum electrolysis has been a long term goal for aluminum industry. The present process for primary aluminum production involves the reduction of alumina with carbon anodes, forming carbon dioxide:"

Jan 1, 2013

By Warren J. Bruckard, Mark I. Pownceby, Sazzad Ahmad, M. Akbar Rhamdhani

Rutile is the preferred feedstock for producing high-grade TiO2 pigment but due to decreasing resources, alternative materials such as ilmenite is now used to produce a synthetic rutile (SR) feedstock. This requires removal of impurities (e.g. Fe, Mg, Mn) which, for a primary ilmenite is straightforward process. Processing of weathered ilmenite however, is complex, especially when chrome-bearing impurities are present since minor chromium downgrades the SR market value as it imparts color to the final TiO2 pigment, Chrome-bearing spinels are a problem in weathered ilmenites from the Murray Basin, Australia as their physical and chemical properties overlap with ilmenite making separation difficult. In this paper, different sulfidation process routes for weathered ilmenites are analyzed for their applicability to Murray Basin deposits as a mean of remove chrome spinel impurities. Thermodynamic and experimental studies indicated that selective sulfidation of chrome-bearing spinel can be achieved under controlled pO2 and pS2 processing conditions thereby making them amenable to separation.

Jan 1, 2015

By John A. Thorpe, Gary R. Maxwell, Kirk M. Schall, Kenneth A. Brunk

"Gold ores containing oxide and some sulfide copper minerals incur significant cost penalties when leached with cyanide, because 4-5 moles of cyanide are consumed for each mole of leached copper. This equates to ~4 kg of NaCN per kg of leached copper. Total cost of excess NaCN consumption plus CN destruction can exceed $4.00 per tonne of ore. AuGMENT Technologies has patents pending on a process that can 1) economically recover 70-80% of the cyanide that is fed to a mill, 2) produce salable copper cathodes, and 3) reduce the need for a cyanide destruction facility. Standard equipment for resin processing and electrowinning are used to recover the cyanide and produce the copper cathodes. Steps have been taken to determine: 1) how to develop the resin kinetics, 2) how much savings are incurred at a mill site, 3) how the novel 'electro-elution' circuit achieves efficient operation.IntroductionWhen gold ores containing nuisance copper are leached with cyanide, a significant cost penalty is incurred because 4-5 moles of cyanide are consumed for each mole of copper that leaches. This is equivalent to the use of -4 kg of NaCN per kg of copper that leaches. The total cost of excess NaCN consumption plus cyanide destruction can exceed $4.00 per tonne of ore.AuGMENT Technologies has a patent pending on a process that can 1) economically recover 70-80% of the cyanide that is fed to a mill, 2) produce salable copper cathodes, and 3) reduce the need for a cyanide destruction facility. This ACCS (Au-.C.u-.C.N Solution) Process Technology involves the novel application of copper cyanide chemistry. Standard resin processing and electrowinning equipment are used to recover the cyanide and produce the copper cathodes."

Jan 1, 1997