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By M. Sizgoric

Certain types of mineralogical alteration due either to weathering or serpentinization, and the effects these transformations have on the flotation of nickel sulfide ores are discussed. These effects are generally deleterious due to: (a) the poor flotation properties of the alteration minerals (as in the case of tochilinite), (b) the nature of the alteration texture (as in the case of violarite), or (c) .close association of the alteration products with other undesirable minerals (such as nickeliferous smythite). Several examples from INCO Metals Company's mines and mineral prospects are given as illustration.

Jan 1, 1981

By D. M. Hausen

Multiple drill sections through many of the numerous breccia pipes in the American Eagle copper deposit at Copper Creek, Arizona, have been evaluated by means of alteration and geochemical data. Contoured plots indicate vertically plunging, concentric, cylindrical shells of alteration and mineralized rock that are similar in structure, geometry, magnitude and petrology to the San Manuel-Kalamazoo Deposit, located about 14 miles to the southwest. Both deposits are similar in dimension and consist of multiple, irregular, rod-shaped injections of porphyry into a granodiorite host. Analogous to the San Manuel-Kalamazoo Deposit, most of the porphyry plugs are oriented parallel to the cylindrical axis of the "ore shell". A continuously mineralized, elliptical shell, inferred from deep drilling, is capped by a flatter zone of copper mineralization. Above this flat zone, copper-bearing fluids were channeled upward along conduits that correspond with quartz-sericite "breccia pipes". At depth, zones of sericite and K-feldspar alteration products exhibit conformable relationships with the copper deposition. A "bullet-shaped" ore shell, with a nearly vertical axis, is proposed to explain the conformable zones of altered and mineralized rock. The "nose" or top of the "bullet" is 1800 to 2300 feet below the surface, and structurally controlled in part by steeply dipping Hi and ENE faults. If correct, this model suggests that the vertical ore shell may extend to great depth.

Jan 1, 1988

By Shunsuke Yagi

A surface alloying technique was investigated using alternating pulsed electrolysis in an aqueous solution containing a single metal component for the formation of an Fe-Cr layer on an iron substrate. In the process, the iron substrate was dissolved during each anodic polarization of the pulsed electrolysis, providing iron ions in the vicinity of the substrate, while the Fe-Cr alloy was electrodeposited during subsequent cathodic polarizations. A bright, flat, and crack-free Fe-Cr layer with a composition gradient was obtained using a solution containing a trivalent chromium component and a complex forming agent together with some supporting or buffering salts.

Jan 1, 2006

By Tiffany Brown

In the thiosulfate gold leaching process, thiosulfate is used to complex gold following electrocatalytic oxidation of the native metal by Cu(II)-ammines. Unfortunately, Cu(II) complexes also catalyse the undesirable conversion of thiosulfate to polythionates. We have been seeking alternatives to ammonia, which fulfil the role of ammonia but minimize thiosulfate decomposition. One aspect of these studies has involved the determination of the rate of thiosulfate oxidation by the Cu(II) complexes from UV-Visible spectral changes. Various ligand classes, including pyridyls, polyamines, aminocarboxylates and picolinates, have been tested and the majority found to inhibit thiosulfate decomposition. Interesting variations in reactivity with the nature and denticity of the ligand and L/M ratio have been observed. In the case of open chain polyamine ligands with 2 to 5 nitrogen donors, the rate of thiosulfate oxidation was generally found to decrease with the denticity and the concentration of each ligand. Saturation of the Cu(II) coordination sphere appears to inhibit the oxidation of thiosulfate when excess thiosulfate is present. The Cu(II) complex of the branched polyamine ligand, tris(2-aminoethyl)amine (tren) exhibits this behaviour in excess thiosulfate. Interestingly, when the [Cu(tren)(OH2)]2+ complex is in excess oxidation of thiosulfate was observed. This unexpected finding prompted a spectrophotometric study of this reaction which has revealed that the oxidation of thiosulfate involves several processes, two of which involve the formation and decay of a tetrathionate radical.

Jan 1, 2003

By Junmo Ahn

This study investigated leaching kinetics by alternative lixiviants for copper leaching from chalcopyrite (CuFeS2), the most abundant copper resource in the world. As a refractory sulfide mineral, chalcopyrite shows low copper extraction due to passivation on chalcopyrite surface. Also, decrease of copper grade with high portion chalcopyrite requires the alternative leaching procedure to increase copper recovery. Therefore, alternative lixiviants such as sulfurous acid and methanesulfonic acid (MSA) were tested for both concentrate and low grade ore to enhance copper extraction. Also, an oxidant, hydrogen peroxide, was compared to ferric to find out the improvement of leaching kinetic. In concentrate leaching tests, 30 g/L MSA showed the highest copper extraction (47%), compared to other lixiviants at 75 °C. Periodical H2O2 addition enhanced copper extraction, and above 90% of copper extraction was observed within 96 h by periodical addition of 0.6% H2O2 at 75 °C. The activation energy of chalcopyrite leaching by MSA and H2O2 achieved 40 kJ/mol, which is chemical reaction control. The results of low grade ore leaching tests indicates that no significant difference among lixiviants (H2SO4, H2SO3 and MSA) with ferric was observed, all of which achieved around 37% within 24 h at room temperature. However, significant increase of copper extraction (>80%) was observed at both 20 g/L MSA and 10 g/L H2SO4 conditions by the addition of 10% H2O2.

By W. G. Davenport

Chapters 7,8and 9 calculated three combinations of: blast composition (mass% O2, mass% N2) oil quantity per tonne of concentrate blast temperature that will steadily produce molten 65% Cu matte from pure chalcopyrite-concentrate. The combinations are:

Jan 1, 2001

By E. James Quinn

Solvent extraction technology using EHEHPA (2-ethylhexyl phosphonic acid, 2-ethyhexyl mono ester) is the norm for industrial separations of rare earth elements. This process has some shortcomings, including a large number of stages compared to most SX processes and high acid requirement for stripping of the heavy rare earths. In this work, we examine a number of alternative mixed solvent extraction systems: (i) Mixtures of organophosphonic and phosphinic acids such as EHEHPA/Cyanex 272 or Cyanex 572; (ii) Ionic liquid mixtures of EHEHPA with quaternary ammonium chloride (Aliquat 336); and (iii) Mixtures of carboxylic acids for yttrium/lanthanide separations. We discuss and compare the efficacy of these systems with reference to the Nd/Sm separation, which is of industrial significance. Based on the extraction chemistry and the use of modelling tools to define the counter-current solvent extraction circuit, we present a techno-economic analysis of a separation plant and discuss the impact of various solvent systems on the capital expenditure (CAPEX) and operating costs (OPEX).

By Marcos Aurélio S. Costa, Nilton F. Nagem, Andreia B. Henriques, Herman S. Mansur, Alexandra A. P. Mansur, Antonio E. C. Peres, Valeria G. Silva

The superfine material generated in the Bayer process was used in one innovatively way as a precursor to geopolymerization techniques because of the presence of Gibbsite. Gibbsite can play a role in system adjustment because of the SiO2/Al2O3 ratio. Furthermore in the geopolymeric system it was studied the influenceof the additives such as kaolin, metakaolin and sodium trisilicate in an alkaline media. Others conditions to form the geopolymer were also evaluated such as solid/liquid ratio, SiO2/Al2O3 ratio and total alkaline. The raw materials and geopolymeric products were characterized by several techniques e.g. XRD, DSC, FTIR and SEM. Through the FTIR technique it was observed an increase in intensity and bandwidth in the region centered at 1010 cm-1, which is related to the asymmetric vibration Si(Al)-O, this is an indicating of the possible geopolymer formation This broadening of the band promotes a relative disappearance (overlapping) peaks at 965 and 935 cm-1 associated with raw material (ESPDust).

Jan 1, 2015

By Tarek M. Abd El Hamid, Suzane Ali

"Treatment of industrial waste materials is created serious problem in Egypt. Aluminium sludge is generated as a by-product from aluminium household industry which contains significantly high alumina content exceeding 90%. This by-product randomly disposed and creates serious environment problems to locate community. To develop the treatment process of this material, the recovery of high purity alumina and identify the potential application is being the primary objective, This paper represents the recovery process of alumina process waste sludge High purity alumina material <99.8% aluminium oxide with originate particle size 0.125-0.420mm and apparent density 0.39g/cm3 was obtained with a specific surface area 139m2/g. Alumina produced was modified by cerium oxide doped alumina. The catalytic activity and selectivity was investigated in conversion of iso-propanol via dehydrogenation reaction yielding only acetone indicating an excellent selectivity the dehydrogenation. The presence of 10% CeO2 increase in the catalytic activity of 82% for the originated alumina. Introduction Approximately 20 thousand tons of aluminium waste produced in Egypt in 2006 with increasing amounts expected in succeeding years. A part of this waste contains organics impurities which coexisted with aluminium waste as a result of manufacture final aluminium products, waste usually content <1 to 2 wt% of organic carbon. It's generally admitted that the organic species are present in the form of lubricant oils used in rolling and pressing equipments for aluminium sheet. Both industry and government face possible high-cost disposal problems that more magnified by large volume of waste produced. The alumina recovery leachable study conduct in this paper had the following objectives: 1- Develop a process that can provide an environmentally acceptable residue and also recover the available alumina. 2- Evaluate the alumina produced in terms of grade and catalytic application."

Jan 1, 2008

By Jr. Robison

"Aluminothermic (""thermite"") smelting became commercial with the development of tonnage aluminum, and prospered producing metals and alloys with higher cleanliness, consistency and elemental control than competing technologies. We explore the scope of thermite smelting, and metallothermic smelting in general; the thermochemistry of the process; and its advantages and limitations as applied to industrial production. We review currently-produced products of thermite smelting in several forms and a wide range of heat sizes. As these products serve several industries, we relate the demands of those industries to the requirements imposed on the thermite process, leading to process dynamics and mechanisms to control/alter those dynamics. We review ways to lower the process costs by altering process stoichiometry, using other energy sources and utilizing less costly materials while considering effects on product quality and customer requirements. Finally, we examine overall emissions control and waste disposal.IntroductionAluminothermic smelting is the reduction of various oxides by aluminum to produce metals or alloys with varying levels of residual aluminum. One of the earliest uses of the process was the production of liquid iron to weld railroad rails, later modified in ""thermite grenades"" used to ""spike"" artillery pieces in World War II. Then during the 50's, 60's and 70's the growth of jet aircraft created a demand for new superalloys and titanium alloys, both requiring master alloys for efficient production. Aluminothermic smelting grew with the aerospace industry and with the expansion of microalloyed steels. It is very much a niche industry, dependent on the specialized demands of the specialty steel, superalloy and titanium industries. In this paper we introduce the characteristics of aluminothermic smelting, the scope of smelting operations, the markets served, and the environmental aspects of the process, as seen through the eyes of a company using aluminothermic smelting for over fifty years"

Jan 1, 2012

By Sang-Beom Lee

For thermodynamic prediction, the deoxidation equilibrium of aluminum in Fe-36%Ni alloy was studied with a cold crucible under Ar gas atmosphere at 1773K. For the deoxidation reaction in liquid Fe-36%Ni base, i.e.: A12O3(s) = 2A1 + 3O The interaction parameters and the equilibrium constant between aluminum and oxygen in liquid Fe-36%Ni alloy are given in the following: eo Al = -3.8, roA1=0.9, eAl° = -6.4, rAl° = 700, rAIAIo = 3.1, roA1o = 833 within the composition range of [Al] < 1 mass%. The temperature dependence of the equilibrium constant was obtained in the range of 1773K < T < 1973K by using reported data and present results as follows: log KAo= 0.58-24463.7 / T The deoxidation equilibrium with aluminum in Fe-36%Ni could be thermodynamically well described in the range up [Al] < 1 mass% with first and second order interaction parameters as well as the equilibrium constant determined in this study.

Jan 1, 2002

By J. Riccardi

Copper refineries use massive copper castings as moulds into which impure molten copper from the reverberatory furnace is poured to form anodes for further electrolytic refining. To facilitate removal of the copper anodes from the mould and to prolong the life of the mould itself, it is traditional to spray the mould surface prior to each use with a slurry of baryte in water. This slurry application leads to poor housekeeping, operating costs are escalated by the cost of the slurry, and additional problems in the subsequent refining process are experienced due to carry-over of excess undesirable baryte powder. A one-time application of a diffused layer of aluminum to the surface of the copper mould prior to putting the mould into service has been found to provide extended mould life and facilitate anode removal, as well as reducing baryte consumption; thereby reducing operating costs at both the anode manufacturing and refining stages.

Jan 1, 1999

By Dale A. Zuck

Recovery of aluminum metal from drosses? is a major factor in the recyclability success story enjoyed by the United States aluminum industry. Today&apos;s modern dross processor uses the latest technology to maximize metal recovery at the lowest cost while complying with all environmental laws and regulations. Most dross processors, however, pay little attention to the resulting saltcake, the end residual of dross recyCling, and rely on landfills for .disposition of this material.. The alternative is to recycle the saltcake, but the success of this technology is dependent on the development of reliable outlets for each of the saltcake constituents. This paper discusses the evolution of an aluminum dross oxide processing technology that ,produces an economically attractive source of alumina for the production of portland cement.

Jan 1, 1995

By V. Kamavaram

Ionic liquids are novel salts used as potential non-aqueous electrolytes for aluminum electrolysis at low temperatures. In the current research di-alkylimidazolium chloride ionic liquids such as 1-butyl-3-methylimidazolium chloride ([BMIM]Cl) and 1-hexyl-3-methylimidazolium chloride ([HMIM]Cl) were investigated for aluminum electrolysis. Melt formed by mixing ionic liquid with AlCl3 is termed as chloroaluminate and is composed of several polymeric chloroaluminate anions. Ionic liquids are studied as electrolytes for aluminum electrowinning and electrorefining of aluminum based materials (A356, A360, & Al-MMC) at low temperatures. Mechanism of aluminum electrodeposition in these chloroaluminate ionic liquid electrolytes was investigated using electroanalytical techniques such as cyclic-voltammetry and chronoamperometry. Aluminum electrodeposition on pure copper substrate in AlCl3-[BMIM]Cl (1.5:1.0) electrolyte at 30°C melts was found to be quasi-reversible process with a charge transfer coefficient ( of 0.40. Chronoamperograms obtained at different voltages in the range (-0.1 to -1.0 V) revealed that the initial stages of aluminum deposition in AlCl3-[BMIM]Cl melts was instantaneous nucleation followed by diffusion controlled growth of three-dimensional aluminum nuclei. The diffusion coefficient of electroactive species Al2Cl7¯ in AlCl3-[BMIM]Cl melts was found to be 6.5×10-7 cm2 s-1 from Cottrell?s equation and 3.9×10-7 cm2 s-1 from the dimensionless current-time transients.

Jan 1, 2006

By Mingming Zhang

This paper describes the aluminum electrowinning in a batch recirculation cell system using 1-hexyl-3-methylimidazolium chloride and aluminum chloride (ionic liquids) as electrolyte at low temperatures. The technique proposed to deposit aluminum from ionic liquid electrolyte was a three-component electrolytic cell system. Ionic liquid electrolyte was circulated between electrolytic cell and electrolyte reservoir by ceramic piston pump. Two different anodes were used in the electrowinning and it was found the extruded carbon anode had better electrochemical stability and reusability. The cell performance variables studied were the current density and current efficiency as a function of aluminum ion concentration, electrolyte flow rate and applied cell voltage during batch recirculation operation. Results indicated that the current density was directly proportional to the applied cell voltage, initial electrolyte concentration and electrolyte flow rate. Under batch recirculation operation at applied voltage of 3.5 V and temperature of 80-90°C, 80-90% current efficiency of cathodic aluminum deposition can be achieved when flow rate is 20mL/min and initial concentration is 10 mol/L.

Jan 1, 2006

By Jason Graetz

Aluminum hydride is a covalent, binary hydride that has been known for more than 60 years and is an attractive medium for on-board automotive hydrogen storage, since it contains 10.1 % by wt. hydrogen with a density of 1.48 g/ml. There are at least 7 non-solvated AlH3 phases, namely a, a&apos;, a, ?, d, e and ?. The properties of a-AlH3, obtained from the Dow Chemical Co. in 1980, have been previously reported. Here we present a description of the thermodynamic and kinetic properties of freshly prepared a, 0 and y phases of AlH3. In all cases the decomposition kinetics are appreciable below 100" C and all will meet the DOE 2010 gravimetric and volumetric vehicular system targets (6 wt% H2 and 0.045 kg/L). However, further research will be required to develop an efficient and economical process to regenerate AlH3 from the spent A1 powder.

Jan 1, 2006

By Fabiola Alvarez, Ana E. Bote, Daniel Pasquevich

"The oxidation of aluminum and its alloys was extensively studied for improving the corrosion resistance in structural materials having high specific strengths. But this reaction involves the formation of a very thin barrier layer on the metallic pieces. Furthermore, the ·recent development of the directed melt oxidation process for producing metal-ceramic; composites has renewed the interest in the study of interaction between gases and metals. Oxidation experiments in the presence of different chlorine partial pressures and at different temperatures were performed in ·a thermogravimetric balance, and microstructures were analyzed by electronic microscopy and X-ray diffraction. The oxy-chlorination kinetics was determined and the oxide formed W(IS amorphous at temperatures below 600 °C and crystalline .at higher temperatures. The appropriate experimental conditions for the fastest completed oxidation was further determined.IntroductionThe use of fine powders for the manufacture of ceramic components has significant advantages. They include excellent sinterability; low sintering temperature and better microstructure leading to improved mechanical properties. The conventional method of producing fine oxide powders involves controlled precipitation and pirolysis of suitable salts. The main limitation of the high temperature decomposition route is the evolution of environmentally unacceptable and corrosive gases. Controlled precipitation of hydroxides from solutions of salts, followed by thermal treatment involves large volumes of solutions and the calcination step that can induce grain growth (1).Direct oxidation of aluminum metal for producing alumina powder requires high temperatures for the direct oxidation of molten Al alloys by a vapor phase oxidant process (2, 3) or high technological process like thermal plasma reactor ( 4).Oxidation of high purity aluminum (5, 6) below the melting temperature· is initially characterized by a nearly linear reaction rate, followed by a rate which decreases rapidly with further weight gain. However, the oxidation rate of an aluminummagnesium alloy is much faster and it does not conform to any common oxidation law, but it is nearly parabolic at temperatures between 200 and 400 °C, an nearly linear· above 400 °C."

Jan 1, 2000

By Denis Legault, Ghyslain Dube, Ronald Morin, Jacques Bonneau, Daniel Guay, Keith Annett, Raymond Breault

"·The total recycling of all the constituents present in aluminum dross is now an industrial reality for Akan. This is made possible by the combination of two patented processes: the Alcan plasma dross treatment process, operating since 1990 at its Guillaume-Tremblay Works, and the calcium aluminate fabrication process, operating at AlumiCa's new plant in Thetford Mines. The latter process uses the total non-metallic content of the dross, thus rendering possible the complete recycling of aluminum dross.After describing the plasma dross treatment process, this paper will present the calcium aluminate fabrication process and how both processes contribute to close the recycling loop. The characteristics of Nova!™ by-product will also be described, as well as how they contribute to make a calcium aluminate with chemical and physical properties that are highly sought after. This calcium aluminate, produced by AlumiCa, is marketed under the trade name Kwikflux®. AlumiCa's total production is presently sold to a number of steel plants worldwide."

Jan 1, 2000

By Banqiu Wu, Ramana G. Reddy, Robin D. Rogers

Experimental studies on aluminum recycling via electrolysis in ionic liquids were carried out at the temperature of 105°C. Impure aluminum was dissolved at the anode and pure aluminum was deposited on a copper cathode. The products were characterized using an optical microscope, micro-image analyzer, X-ray diffraction, emission spectrometer, and atomic absorption analyzer. The electrorefining process with a current density of 310 - 730 AJm2, and current efficiency of about 99% was obtained. Impurities such as Si, Cu, Zn, Fe, Mg, Cr, Ni, Mn and Pb were removed as anode residue. Impure aluminum was purified from 79.8wt% to 99.9wt%. At a cell voltage of 1 volt, the energy consumption of about 3 kWh/kg-Al was obtained. The process has advantages of low energy consumption and low pollutant emissions, compared with the current industrial refining process.

Jan 1, 2000

By John A. S. Green, J. Gilbert Kaufman, Subodh K. Das

"The aluminum industry is a leading proponent of global sustainability and strongly advocates the use of recycled metal. As the North American primary aluminum industry continues to move offshore to other geographic areas, such as Iceland and the Middle East, where energy is more readily available at lower cost, the importance of the secondary (i.e., recycled metal) market in the U.S. will continue to increase. In the past, the recycling industry had been synonymous with the collection of aluminum beverage cans. However, as the opportunities for aluminum recycling have multiplied in motor vehicles, building and construction, and aerospace, these market are getting additional scrutiny for optimization of recycling strategies.Accordingly, the secondary industry can now draw upon a much wider range of product forms and alloys for its raw material, but this in turn brings issues of alloy sorting, impurity content, and control as the material is remelted and recycled into new product forms. The purpose of this paper is to take an integrated, industry-wide approach to look at the recovery of material from demolished buildings, shredded automobiles, and aging aircraft, as well as from traditional cans and other rigid containers. Attempts will be made to assess how the different alloys used in these separate markets can be recycled in the most energy efficient manner.IntroductionIn his recent book “Aluminum Recycling”[1], Mark Schlesinger points out that in traditional extractive metallurgy, the raw material used to produce a metal is mined from the earth and then is separated from other gangue minerals and impurities. In aluminum recycling, however, the ore body consists of scrap metal found on the ground, rather than in it. He further notes that scrap comes with its own variety of gangue and impurities such as painted coatings, other metal attachments, and even dirt and other contaminants. So, while the recycling process still requires some refinement and expenditure of energy, the effort and energy involved is much less than traditional mining."

Jan 1, 2008