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By Kurt Westerlund

Three. years operating experience of the FLUXFLOW waste heat boiler (WHB) 20.000 nm /h at Boliden Ronnskar Sweden on a TBRC smelting palena (PbS). Operating experience from the Kivset flash WHB 11.900 nm /h at Samim, Porto Vesme, Sardinia, Italy. Conceptual features of the 93.600 nm3 /h FLUXFLOW (WHB) on the Isasmelt smelting in melt furnace for 180.000 t Cu/a at Mount Isa, Australia.

Jan 1, 1992

By Min Chen

A numerical simulation of the stress field of the solidified shell in the mold during continuous casting of peritectic steel slab was calculated with commercial software. The results showed that the maximal stress on wide face of the solidified shell was located at the corner and near middle of the slab, and it increased with increasing the width of slab. In addition, the stress was also influenced by operating parameters such as superheat degree, drawing speed and cooling intensity of the mold, and the maximal stress value and its position changed with these parameters. For the slab with section size of 3200mm×150mm, the proper drawing speed was around 1.2m/min, with cooling intensity of 5500L/min while the superheat degree was 15°C to 25°C in order to prevent longitudinal crack occurring during peritectic steel continuous casting.

Jan 1, 2009

By Ilkka V. Kojo

This paper gives an overview of the primary copper smelting business during the years of flash Smelting in the light of various projects taking into account the sustainability of copper production. Also the future challenges of copper smelting are addressed with special emphasis on the environment. Flash Smelting connected with either Peirce-Smith converting or Flash Converting offers the most economical and environmentally friendly alternatives for the smelting of normal and lean copper concentrates. For rich copper concentrates the feasibility of Outokumpu Direct Blister Flash smelting is, understandably, beyond compare. When the total investment costs for building a smelter and acid plant are considered, it is clear that Flash Smelting is the more feasible option compared to bath smelting. Reduction of equipment and operating cost is further achieved by the LUREC-process developed by Outokumpu Technology for operating plants with SO2-contents up to 25 % by volume. As an example the Kennecott-Outokumpu Flash Converting Furnace (FCF) has been in operation at Kennecott Utah Copper for 10 years and has achieved excellent results both environmentally and production vice. The FCF treats the entire output of the Kennecott Flash Smelting Furnace and has excess converting capacity. Furnace life, initially projected at two to three years, is now projected to be more than 5 years. It is likely the life will be essentially the same as a well-operated Flash Smelting furnace.

Jan 1, 2006

By P. R. Taylor

Diamond films have been successfully formed in an inductively coupled plasma (ICP) chemical vapor deposition (CVD) system from several gas mixtures: CH,-H,, C2112-112, and C2112-112-02' Our previous thermodynamic study indicated that the substrate temperature could be lowered by the presence of oxygen species at moderate system pressures (0.3-0.5 atm) and that higher volumetric growth rates required a high temperature source and a moderate pressure system in CVD processing. The principal experimental results were consistent with the thermodynamic predictions. The deposited films were characterized by laser Raman spectroscopy, scanning electron microscopy, and X-ray diffraction. The films were well faceted and uniform, with the growth rates over 10 pm/hr on molybdenum substrates. The crystal size ranged between 1 and 2 microns for a two hour experiment. It was possible to decrease the substrate temperature to below 800 °C in this system.

Jan 1, 1995

By Habib Saridikmen

In this experimental study the effects of slag composition on the phosphide capacities of the slag as well as on the phosphorus distribution ratios between the slag and metal phases encountered in ferromanganese smelting have been determined at 1500°C under carbon monoxide atmosphere. The distribution results were employed to calculate the phosphide capacities of the SiO2-Al2O3-CaO-MgO-MnO slags in equilibrium with the Mn-Fe-Si-Csatd.metal phase. The classical gas-slag-metal equilibrium-quenching technique was employed using CO gas atmosphere and graphite crucibles to saturate the metal phase with respect to carbon. The phosphorus distribution ratio increased from 0.045 to 0.375 when the slag basicity increased from 0.72 to 1.39. As expected, the distribution ratio decreased from 0.375 to 0.105 when silica increased from 37 % to 45.8% in the slag phase. The phosphide capacity values were calculated by using the results of experiments. Empirical relationships were developed to express the phosphorus distribution ratios and phosphide capacities of the above slags.

Jan 1, 2006

By Janene Barter

Telfer Gold Mine treats both gold/copper oxide and sulfide ores in a remote location in the Great Sandy Desert, Western Australia. Currently, the oxide gold ore is treated in a conventional CIL circuit by blending the low and high grade copper ores to minimise cyanide consumption and allow smooth operation. The sulfide ore is treated through a flotation circuit to produce pyrite and copper concentrates. The pyrite concentrate is treated in the CIL. Copper concentrate is stockpiled and sold to a smelter for further processing. In recent times, as the depth of the pit has increased the copper head grade has also increased, to the point where the ore was becoming uneconomical to treat. In addition, it was desirable to reduce the amount of cyanide reporting to the tails dam both from an environmental and economical viewpoint. Newcrest Mining Limited engaged GRD Minproc Limited to evaluated a process to reduce the amount of cyanide entering the tail dam with consideration given to copper recovery. From this investigation, the Sulfidisation, Acidification, Recycle and Thickening (SART) process was selected. A detailed testwork program for SART was undertaken with the objective to design and construct a SART plant at Telfer. This paper outlines how the SART process was chosen and summarises the testwork that led to the design of the SART plant. It also touches on some of the important issues for designing this type of process.

Jan 1, 1998

By F. Tailoka

In order to decrease the voltage required for electrorefining, a recessed electrode cell has been developed in which the anode and cathode have recesses machined into their faces. The anode and cathode plates are separated by a thin refractory cloth and the cell is filled with fused salt. Bismuth containing 10 to 90 % lead with copper and silver as minor impurities has been electrorefmed at a current density of 10,000 to 20,000 Am-2. The cell voltage was between 285 and 635 millivolts and the bismuth was refined to a purity of 99.9 %. Flow patterns were observed in a room temperature model of the recessed channel cell using water and mercury to simulate molten metal and the fused salt electrolyte. The flow in the electrode recesses is characterized by discrete droplets when the liquid flow rate is low and thin streams and rivulets at higher flow rates.

Jan 1, 1995

By Neil Rowlands

Particle liberation studies are commonly used in the determination of the proportion of locked and liberated phases in ground ores at various stages of mineral processing. These studies may range from a qualitative assessment of a polished specimen in an optical microscope to a full quantitative analysis of the liberation characteristics of fine grained complex sulfide ores using scanning electron microscopy and high level image analysis. However, the conversion of quantitative data to meaningful information on a mill operations level is by no means a simple task. This paper reviews the errors inherent in the SEM/Image Analysis technique and looks at the various methods available to minimize errors in data collection.

Jan 1, 1992

By Akram Alfantzai, Farzad Mohammadi, Maysam Mohammadi

"Degradation of lead anodes has always been a major concern among the electrowinning industries. In this study, the effect of agitation of the zinc electrowinning solution on the integrity of lead anodes was investigated. Galvanostatic experiments were performed at 37±0.5°C using 0,600 and l000rpm magnetic stirring rates for 24 hours. The Pb02 layer formed on the anode surface was reduced to PbS04 (discharged). The discharge information was used to calculate the amount of Pb02 present on the surface. Weight loss measurements along with the discharge calculations revealed that the degradation rate of the lead anode increased as the solution was stirred more vigorously. Furthermore, the amount of remaining Pb02 on the surfaces was decreased as a function of solution velocity. Therefore, it may be concluded that, degradation rate oflead anodes is controlled by detachment of the corrosion products from the surface rather than by electrochemical reactions. IntroductionElectrowinning is one of the extraction stages of zinc, in which pure zinc is deposited from acidic solution after froth flotation, roasting and leaching processes. The anode electrode materials play important roles in the electrowinning process. Their electrocatalytical capacities determine the oxygen evolution overpotential, and consequently the cell potential and energy efficiency of the zinc electrodeposition [l]. Purity of the zinc deposited on the cathode is affected by the solubility and corrosion resistance of the anode materials. Using insoluble materials as anode in the electrowinning leads to the higher purity of the deposited metal on the cathode[2]. Lead (Pb) and its alloys have been used as the anode in the zinc electrowinning because of its special properties such as relatively low cost, low melting point, insolubility in solutions containing sulphuric acid and high conductivity in both states of metallic and oxidized [3, 4]. In zinc electrowinnig, zinc reduction occurs on the cathode (reaction 1) and the oxygen evolution reaction (OER) (reaction 2) is the main anodic reaction [5, 6]."

Jan 1, 2013

By David C. Lynch

FeCl3 particulate of 10 to 100 um in diameter was reacted with radicals produced in an oxygen plasma at pressures between 1 to 20 Torr. The particulate, in a fluidized bed, was positioned above the plasma to avoid over heating the oxide product which is known to lead to crust and clinker formation[ 1 ]. Reaction between the iron chloride and the gas phase occurred at temperatures between 66 and 226 °C. Oxygen radicals react with the surface material to a depth of approximately 2.5 4m. Surface material, analyzed with a x-ray technique, indicates that the maximum amount of FeCl3 reacted on a weight basis was found to be approximately 67%. More typically, 40 to 50 wt% of the chloride was reacted within 30 minutes to 1 hour.

Jan 1, 1996

By Junji Shibata

The waste acid mixture whose main component is phosphoric acid, is discharged from the etching process in the liquid crystal production industry. In order to separate impurity acids from the phosphoric acid, trioctyl phosphate (TOP) is used as an extractant. TOP can extract acetic and nitric acids selectivity. The extraction and stripping operations are carried out for the acid mixture by beaker-scale experiments and countercurrent multistage operations with mixer-settler equipment. TOP selectively extracts the acetic and nitric acids in the acid mixture. From the results of the McCabe-Thiele analysis obtained by beaker-scale tests, the extraction for acetic and nitric acids are approximately 100%, respectively, by 6-stage extraction with a phase ratio (A/O) of 0.4. On the other hand, almost all of acetic and nitric acids are stripped with water from the organic phase by 4-stage stripping with a phase ratio (A/O) of 1.0. About 95% of acetic and 98% of nitric acids can be removed from the acid mixture without extracting phosphoric acid in case of the mixer-settler equipment operation. There are several steps such as slicing, lapping, chemical etching and mechanical polishing in the silicon wafer production process. The chemical etching step is necessary to remove any damaged layer caused in the slicing and lapping steps. The typical etching liquor is the acid mixture comprising nitric acid, acetic acid and hydrofluoric acid. The waste acid is treated by a neutralization method with a high alkali cost and balky solid residue. A solvent extraction method is applicable to separate and recover each acid. Acetic acid is first separated from the waste liquor using 2-ethlyhexyl alcohols as an extractant. Then, nitric acid is recovered using TBP (Tri-butyl phosphate). Finally hydrofluoric acid is separated with TBP solvent extraction. The expected recovered acids in this process are 2mol/L acetic acid, 6mol/L nitric acid and 6mol/L hydrofluoric acid. The yields of this process are almost 100% for acetic acid and nitric acid. On the other hand, it is important to recover and reuse the metal values contained in various industrial wastes from a viewpoint of environmental preservation. Most industrial products are made through processes to separate impurities in raw materials, solid and liquid wastes being necessarily discharged as industrial wastes. Chemical methods such as solvent extraction, ion exchange and membrane separation, and physical methods such as heavy media separation, magnetic separation and electrostatic separation are considered as the methods for separation and recovery of the metal values from the wastes. Some examples of the application of solvent extraction to the treatment of wastes such as Ni-Co alloy scrap, Sm-Co alloy scrap, fly ash and flue dust, and liquid wastes such as plating solution, the rinse solution, etching solution and pickling solution are introduced.

Jan 1, 2003

By Feng Ningchuan, Guo Xueyi, Tian qinghua, Liang Sha

"In this study, copper adsorption by orange peel which was chemically treated with sodium hydroxide was investigated. The morphological and chemical characteristics of the adsorbent were evaluated by spectroscopy and N2-adsorption techniques. Equilibrium isotherms and kinetics were obtained and the effects of solutions pH, adsorbent concentrations and temperature were studied in batch experiments. Equilibrium was well described by Langmuir and Freundlich isotherms and kinetics was found to fit pseudo-second order type adsorptions kinetics. According to the Langmuir equation, the maximum adsorption capacities (qm) for Cu(II) was 50.25 mg·g-1 at pH 5.3. With the temperature increased from 16 to 60°C, copper removal decreased. The loaded adsorbent was regenerated using HCl solution and could be used repeatedly at five cycles with little loss of adsorption capacity. The results show additional chemical treatment of the adsorbent by NaOH, is favor of improving the adsorption capacity. Introduction Increased use of metals and chemicals in manufacture industries has resulted in generation of large quantities of effluent that contains high level of toxic heavy metals and it poses environmental-disposal problems due to its non-degradable, persistence nature and accumulation throughout the food chain [1, 2]. Copper is known to be a commonly used heavy metal. This metal, which found many useful applications in our life, is very harmful if charged into natural water resources and may pose finally a serious health hazard. Many methods, such as chemical precipitation, ion exchange, reverse osmosis and adsorption, etc., have been used for heavy metal ions removal from various aqueous solutions. In recent years, there has been considerable interests in use of biological materials including algae, bacteria, fungi, agricultural by-products and residues as adsorbents to remove toxic metals from aqueous solutions by adsorption [3-8]. Adsorption process has been extensively used to remove copper from aquatic medium using low cost adsorbents such as peanut husks [9], plant materials [10] and cellulose materials [11]. Among them, agricultural by-products and biomass are relatively cheap and show very high adsorption capacities. However, to apply untreated agricultural by-products as adsorbents has the disadvantages such as low adsorption capacity, high chemical oxygen demand (COD) and biological chemical demand (BOD) as well as total organic carbon (TOC), due to the release of soluble organic compounds contained in the plant materials such as lignin, tannin, pectin and cellulose, into the solutions [12-14]."

Jan 1, 2008

By Halvor Dalaker, Alain Marc Ferber, Thor Anders Aarhaug, Pål Tetlie

Off-gas monitoring of experimental reactors give little information about intermediate reaction products and reflect chemical equilibria at reduced gas temperatures. A reactor design with optical access was designed and tested in order to be able to qualify and quantify gaseous species from their emission spectra. By use of a sequence of sapphire, UV fused silica and IR transparent sapphire and CaF2 windows and lenses optical access to a hot, maximum 1800 °C, reaction zone was gained. A cooled area behind the reaction zone was used as a background in order to avoid signal saturation from reactor walls. In addition to molecular emission spectra, atomic emission lines are used to characterize stable gas constituents and radicals. The setup has been designed for the study of methane dehydrogenation experiments in order to investigate the carbon activity of reduction of oxide with methane, but has also been used to monitor gaseous silicon suboxide.

Jan 1, 2015

By Dinesh Agrawal

Microwave energy has been in use for variety of applications for over 50 years. These applications include communication, food processing, wood drying, rubber vulcanization, medical therapy, polymers, etc. In the last two decades microwave heating has been also applied very effectively and efficiently to heat and sinter ceramic materials. Microwave heating is recognized for its various advantages, such as: time and energy saving, very rapid heating rates, considerably reduced processing cycle time and temperature, fine microstructures and improved mechanical properties, better product performance, etc. The most recent application of microwaves has been in the field of metallic materials for sintering, brazing/joining and melting. Several common steel compositions, pure metals and refractory metals have been sintered in microwaves to nearly full density with improved mechanical properties. Many commercial powder-metal components of various alloy compositions including iron and steel, copper, aluminum, nickel, Mo, Co, Ti, W, Sn, etc., and their alloys have also been sintered in microwaves producing better properties than their conventional counterparts by using a 2.45 GHz multimode microwave system. This work has been further extended to join and braze bulk metal pieces, especially super alloy based turbine blades. Further, in a specially designed microwave cavity, even the bulk metals can be made to couple with the microwave field and melted. The implications of these findings are obvious in the field of powder metal technology.

Jan 1, 2006

By Daniel Helm

The first industrial application of direct solvent extraction of nickel from hypersaline sulfate feed solutions has highlighted the need to investigate the influence of chloride on the extraction behaviour nickel in the presence of calcium using Versatic 10 and the solubility characteristics of gypsum. Temperature-solubility curves for gypsum in various aqueous electrolytes were prepared. The solubility of gypsum is increased significantly by the presence of sulfate ions, while chloride ions decrease it for a given temperature. The anion effects of chloride and sulfate on the extraction of calcium and nickel by Versatic 10 corresponded well with the complexing ability of the anions. It was shown that the presence of chloride shifts the extraction isotherms for both metals significantly to the left, while decreasing the selectivity of Versatic 10 for nickel over calcium. The loading of nickel onto Versatic 10 in this system was shown to be at a maximum within 3 seconds, while calcium extraction took between 4 ? 5 seconds to load to a maximum. Chloride ions had no influence on loading kinetics of nickel, but depressed the rate of calcium loading. It was shown that in the presence of an excess of nickel, calcium loading is effectively eliminated, and that calcium is scrubbed from Versatic 10 within 2.5 seconds of contact with nickel electrolyte.

Jan 1, 2003

By Ana E. Bohé

Chlorination process is an attractive and efficient method for the metal recovery from complex materials. The process that is performed at high temperatures, allows converting all the metals contained in the material into their respective chlorides which are further separated in a selective way. Aluminum metal matrix composites with discontinuous ceramic reinforcement of short fibers, whiskers, and particles have been gaining wide acceptance as an important engineering material in automotive, aerospace, and electronic industries. Since the ceramic reinforcements are still quite expensive and contribute significantly to the final cost of composite materials, the feasibility of their recovery from the manufacturing scrap and further recycling is a factor of increasing economic interest. In the present work, a theoretical and experimental study is given for the recovery of Al2O3 and SiC particles and short fibers from three commercially available aluminum-matrix composites produced by molten metal mixing route. The process consists of transforming the constituents of metallic alloy matrices in gaseous chlorides that are dragged by the gaseous stream, while the ceramic reinforcement remains as a solid residue in the reaction bed.

Jan 1, 2006

By Osamu Yamamoto

In antibacterial evaluation of carbon-ceramic composites, we prepared two type composites with emphasis on carbon-ZnO system; one was porous carbon materials containing ZnO nano-particles and another was porous ZnO coated with carbon thin film. Porous carbon samples containing ZnO at highly dispersed state were prepared by carbonizing the resin exchanged by Zn2+ ion. Porous ZnO coated with carbon thin film was obtained by the pyrolysis of poly (vinyl alcohol). Antibacterial activity of these composites obtained was evaluated by measuring the changes in electrical conductivity with bacteria growth. The antibacterial activity on the composites increased with the increase of t he amount of ZnO in composite and decreased with the increase of carbonization temperature. The antibacterial activity for Staphylococcus aureuswas found to be stronger than that for Escherichia coli. No activity of the carbon samples without ZnO was observed. The occurrence of antibacterial activity was supposed to be due to the generation of hydrogen peroxide from ZnO in composite. In the present work, antibacterial activity of carbon-ZnO composites was studied in the details.

Jan 1, 2006

By Maria de Campos

The pre-reduction behaviour of chromite particles in methane-argon and methane-hydrogen gas mixtures was investigated between 1050°C and 1250°C. Loose bed of chromite particles were reacted in a vertical tube furnace under a pre-set gas mixture predetermined time intervals. Metallization results were obtained for the Cr and Fe components by chemically analyzing the reaction products. SEM-EDAX techniques and X-ray diffraction were employed to elucidate the reduction mechanism. It was found that higher reduction kinetics and higher Cr:Fe ratios in the metal phase would be achieved when hydrocarbon gas was used in comparison to classical carbothermic reduction at a given temperature. The reduction rate was generally bulk gas mass transfer controlled to the reaction site for initial stages which then was followed by ionic diffusion rate control. It is proposed that methane did not partake directly in the reduction but cracked, presenting the reaction site with hydrogen gas and atomic carbon, which was able to immediately react at the immediate area of reduction regeneration CO and H2 and thus maintaining a low partial pressure of oxygen at the reaction site.

Jan 1, 2006

By Esa J. Peuraniemi

Copper smelting to form blister in one single step has been possible for a long time even from low grade concentrates. In spite of obvious benefits, it has been economically viable only with few special raw materials having high enough Cu/Fe and Cu/S ratio. Outokumpu Blister Flash Smelting is currently applied at three operations, and three others will be commissioned in the near future. With typical chalcopyrite concentrates two main obstacles have prevented wider adaptation of direct blister processing: slag formation and heat generation. Oxygen potential in the reaction shaft must be high in order to produce blister with targeted sulfur content below 1%. When large amount of iron is oxidized, as well as sulfur, copper is inevitably also oxidized into slag. High copper amount in substantial tonnages of slag lead on to costly down stream recovery operations to obtain discardable slag. Almost complete oxidation of sulfur and iron releases a high amount of heat which traditionally has been solved by lowering oxygen enrichment of the blast leading on to oversized off-gas line and acid plant. One challenge in direct blister smelting relates to the attack of aggressive high-copper containing slag against furnace refractory lining. In continuously operated Outokumpu Direct Blister Flash Smelting this is taken care of by preventing vigorous melt movement in the settler. Stable bath conditions and stationary slag against refractory lining enable the formation of a protective autogenous layer between aggressive slag and vulnerable refractory. These direct blister smelting challenges are addressed from equipment and process development point of view. New solutions to overcome the obstacles are presented and discussed.

Jan 1, 2006

By C. M. Acuna

Scarcity of high grade copper low impurity content ores is a reality and processing of low grade dirty concentrates is a need. In spite of this fact, innovative strategies have to be looked at to comply with day to day more stringent environmental regulations. From this perspective the production of matte grades over 70% in copper presents several merits, but it must be contrasted with the fractional distribution of impurities reporting to the condensed phases. Converting of white metal high in arsenic content results in moderate fraction of arsenic to gas, but high deportment to blister. Therefore, production of anode copper, as required by the electrolytic refinery, may result in several operational difficulties. Furthermore, by recycling the flue dust and slag produced in the smelting-fire refining cycle, the arsenic content in the feed to smelting increases and so does in the resulting anode copper. The Teniente Converter, as a smelting unity, has probed suitable for production of high matte grade near white metal composition but regarding distribution behaviour of impurities there is lack of reliable data, specially when processing concentrates over 1% in arsenic content. In the new scenario, i.e. low grade copper high arsenic content concentrates, to fully asses the merits of this technology the effect of matte grade, secondary materials recycling and arsenic in feed upon the distribution coefficient of arsenic between slag and matte, mainly, must be evaluated both from a theoretical approach and by use of industrial data. Based on available data correlations of distribution coefficient, matte grade and matte/slag ratios with arsenic in feed and copper content in slag are worked out. Based on these results suggestions as to matte grades facilitating to deal more efficiently with the handling of smelting byproducts are proposed.

Jan 1, 2006