Search Documents

By R. Togashi, S. Kuramochi, T. Yamada

In 1972, the Akita Zinc Co., Ltd. commenced operations with an annual capacity of 86,000 tonnes of electrolytic zinc, and it has operated with an annual capacity of 156,000 t-Zn since 1974. The business surroundings for non-ferrous metals production have become more severe with the high Yen rate for the dollar and low domestic demand in the last few years. Consequently, the company tried to survive with some improvements and succeeded to reduce operating costs and to improve profitability as follows: 1) expansion of its production capacity to. 196,000 t-Zn annually, 2) saving man-power by the introduction of fully-automated machines for cathode handling in the cellhouse, 3) improvement of the hematite process by means of the recovery of rare-metals. These improvements made Akita Zinc a competitive refinery in the modern world. We have been trying to improve the operations more and more. One of the challenges is to purify the iron oxide made in the hematite process by applying an As removal process, which is coming into operation in the near future.

Jan 1, 2000

By Jin Liu

In the early 1990?s, Inco successfully installed two new flash furnaces as part of their SO2abatement project to reduce SO2 emissions from the Copper Cliff Smelter by 60%. The flash furnace off-gas is cooled and cleaned through two new Monsanto Dynawave gas cleaning systems that replaced the traditional venturi scrubbing system. It was discovered that the flash furnace production capacity is often limited by the capacity of the gas cleaning system. The key task is to eliminate pressure drop from the system. The froth column is responsible for by far the largest pressure drop in the gas cleaning system. Initially, the column was fitted with 22 plates. In 1994, both #1 and #2 froth columns were modified by reducing the number of plates in each column from 22 to 18 and increasing the interplate spacing on lower plates. With increasing demand for more throughput in the flash furnaces, further modifications on the froth columns were made in 2005. This paper describes these modifications and results together with some fundamental analysis of the froth column characteristics.

Jan 1, 2006

By G. Achurra

The products of the smelting of copper concentrates in an El Teniente Converter (CT) are a high grade matte, analyzing 74-76% Cu; and a highly oxidized slag, typically containing 15-20% Fe3O4 and 4-10% Cu. The El Teniente Division of CODELCO¬CHILE has developed a slag reduction-cleaning process, that is practised in a tilting, horizontal furnace, to recover copper from these slags. The El Teniente slag cleaning process has been successfully implemented at the El Teniente Caletones smelter and various other smelters in Chile: Today, eight such slag cleaning furnaces, each with a capacity of 800-1000 tonnes/day, are in operation in Chile. This paper discusses basic laboratory research and industrial tests that led to substantial reductions in the slag cleaning cycle time and the specific consumption of fuel and reductants. Simultaneously, the slag cleaning off-gas quality was improved. Based on the experimental results, recommendations were made to improve the practice of the El Teniente slag cleaning process. The recommended modifications have been fully implemented at the Caletones smelter.

Jan 1, 1999

By R. A. Sharma

Neodymium metal was successfully produced by the reduction of Nd203 with Na in the presence of CaC12-NaCl melts by the overall reduction reaction Nd203 + 3 CaC12 + 6 Na ? 2 Nd + 3 CaO + 6 NaCl at -750°C. The metal produced was extracted from the salt media by dissolving it in a Nd-Fe alloy pool. The yield (percentage of theoretical neodymium produced) was found to depend on the salt composition and the mass ratio of salt to neodymium in the reactor. A yield of 95% was obtained with salt ratios as low as 3.5. Further decrease in the salt ratio below 3.25 decreased the yield. Stirrer position had little effect on yield; while increasing the temperature and placing fins in the reactor increased the yield. The Nd-Fe alloy produced was of as good quality as that produced using Ca reductant, and was suitable for direct use in producing General Motors MAGNEQUENCH? alloy for permanent magnets.

Jan 1, 1989

By Jeong-Hwan Kim

The liquid-liquid reactive process (solution process) is often adopted as a synthetic method for precipitated calcium carbonate (PCC) in laboratory studies for its simplicity in operation or ease in controlling process variables. Still, PCC are produced commercially by passing carbon dioxide through a milk of lime, i.e., by a gas-liquid reacting method (carbonation process). Few studies on the carbonation process have been conducted, since the process variables are interrelated and difficult to control compared to the solution process. In this study, both carbonation and solution processes were employed to study the polymorphs of calcium carbonate and growth rate of PCC crystals. The effects of the characteristics of limestone ores as a raw material in the synthetic system of PCC on the synthetic characteristics of PCC were also investigated. To control the nucleation rate in the synthetic systems, the shape factor was considered most important. Single-phase aragonite PCC could be synthesized under a variety of controlled experimental conditions such as ionic strength, solution composition, concentrations of additive ions, and temperature.

Jan 1, 2006

By Manuel Alvarado, David Nemir, Jan Beck

"Thermoelectric generation using special N-doped and P-doped semiconductors is well known as a means for direct heat energy to electrical energy conversion without the need for moving parts. The technology is used today in niche markets for low level electricity production and has been proposed as a scalable means for capturing large scale energy from waste heat streams. The choice of geometry of the thermoelements and conductors is critical to the successful implementation of a waste heat recovery system in order to manage losses due to Joule heating and diffusive heat flows. This paper describes a simulation study to define the performance impact of different aspect ratios for the active thermoelements and the electrical interconnect. The use of a finite element model that incorporates the intercoupled heat and electrical energy flows highlights some of the issues impacting scalability.IntroductionThermoelectric phenomena arise out of the intercoupled electrical and thermal currents in a material. A two-element thermoelectric generator is depicted in Figure 1. It is constructed by connecting an N-type thermoelement and a P-type thermoelement in electrical series, with both elements in thermal parallel between a heat source and a heat sink. The electrical series connection is made by attaching conductors as shown. Ideally, these series connection elements will be both good thermal conductors and good electrical conductors.The two element generator in Figure 1 is disposed between two thermal reservoirs: the heat source, which furnishes heat energy; and the heat sink, which absorbs heat energy. Heat energy flux Q, flows from the heat source to the heat sink, driven by the temperature difference between the source and the sink. As depicted in Figure 1, when a resistive load, R, is attached, electrical current, I, may be extracted from the thermoelectric generator and furnished to the load. The N-type and P-type thermoelements, are the active portions that do the actual conversion of heat energy to electrical energy. Although thermoelements may be built using conductors such as bismuth and antimony, higher efficiency thermoelectrics are built using heavily doped semiconductors. Thermoelectric devices are generally formed by connecting many pairs (couples) of N and P type thermoelements in electrical series and in thermal parallel. A commercially available module having 127 couples (254 elements) is shown in Figure 2."

Jan 1, 2011

By Ana P. Paiva, Marc F. Comella, Sandra S. Reis, Joao N. Reis, M. Soledade Santos

"In this work, the influence of the malonamide structure, acidity of the aqueous phase and diluent on the equilibrium interfacial tension (IT) of N,N'-dimethyl-N,N'-diphenylmalonamide (DMDPHMA) and N,N'-dimethyl-N,N'-dicyclohexylmalonamide (DMDCHMA) in 1,2- dichloroethane (1,2-DCE), and DMDCHMA in toluene, with aqueous HCl, were investigated. IT isotherms were determined using the Du N ouy ring method. Densities of the organic phases were determined, and used to screen solute-diluent interactions. Formation of third phases was never observed; furthermore, ITs increase with the phase separation period, constant values being obtained for separation periods larger than 1000 seconds. Each malonamide interfacial efficiency at the oil/water interface is interpreted in terms of malonamide basicity, diluent polarity and malonamide - hydrochloric acid- diluent interfacial interactions.IntroductionFor several years now, N,N'-tetrasubstituted malonamide derivatives have been extensively investigated as liquid-liquid extraction agents since they were first proposed as the organic components of the DIAMEX process, with the aim of advantageously replacing tributylphosphate in PUREX [1]. Therefore, a significant part of research studies with malonamides appearing in the literature deal with the extraction of major and minor actinides in real or simulated spent nuclear fuels in nitric acid solutions [2]. Under typical experimental process conditions, the tendency shown by some N,N'-tetrasubstituted malonamide derivatives to aggregate in the organic phase, leading in a few cases to the formation of undesirable third phases, has been remarked and consequently thoroughly investigated [3, 4]. The increasing use of chloride streams as hydrometallurgical aqueous feeds is becoming a reality, and this fact is obviously deeply founded on an extensive research carried out to recover value-adding metals from these media. Following this trend, a number of N,N'-tetrasubstituted malonamides have already been screened for the recovery of iron(III) [5, 6] and platinum-group metals [7] from hydrochloric acid solutions. The results obtained are quite promising either in terms of total metal ion recoveries or selectivity patterns achieved. The formation of a third phase when iron(III) was extracted by the tested N,N'-tetrasubstituted malonamide derivatives has never been observed under the adopted experimental conditions, and the extraction data collected would need to be reinterpreted accordingly if any aggregation phenomena involving the considered extraction systems were to take place."

Jan 1, 2011

By Xi-chang Shi, Yun-feng Fu, Bai-zhen Chen, Hui Xu, Xiang Xiao

"Extracting boric acid from saline brine by boron specific ion-exchange resin was investigated. Effects of resin amount, temperature, time and stirring speed on boron adsorption rate were studied in the experiments. The results indicated that the XSC-700 resin showed excellent boron absorbability and it performed better property for elution. The maximum boron adsorption capacity was 6.16 mg/ml in the optimum conditions: the resin concentration of 5 ml/(100 ml brine), the temperature of 60°C, the time of 5-6h and the stirring speed of 100 r/min. Boron was eluted from the resin with HCl and boric acid was crystallized by evaporating the eluate. The product of boric acid was in pure form as confirmed by XRD and other analysis techniques.1 IntroductionBoron has a number of minerals in nature such as tincal, colemanite, ulexite, and kemite, etc. [1-2]. Boron and its compounds are chemical materials of significant value. The principal industrial uses of boron compounds are in the production of glass, porcelain, enamels and detergents. Other uses include fertilizers, metallurgy, and nuclear shielding [3-4]. In recent years, because of the large-scale mining boron ore, ore resources are drained gradually. With the development of science and technology, the boron mineral resources will be unsatisfied with the future requirement. There exits abundant boron resources in salt lakes which cover about 40% of the total reserves in China. If we can obtain boron from salt lakes, it will produce great economic interests [5-6]. Therefore, actively seeking boron from salt lake and other resources in suitable conditions has become a hot spot in the research organizations of boron resources development and utilization in the world [7].There are many methods such as acid crystallization, solvent extraction and ion exchange processes suggested effective for boron extraction from aqueous solutions. Acid crystallization method has the shortcomings of complicated procedures, the pollution caused by hydrochloric and other ingredients returning to salt lakes during the extraction process. Although solvent extraction process increases the boron acid recovery efficiency, the cost of production is high [8-9]. However, Chelating resin extracting boron has the characteristics of simple process, easy operation and no pollution. It was reported that chelating resins containing functional groups show a high selectivity for boron extraction [10-12]. Therefore, ion exchange technique which is now the most practical application of significance and most extensively used ha"

Jan 1, 2011

By Patrik Fredriksson

Thermodynamic data concerning FeO-containing slags is of importance in ladle refining of steel. With a view to generate a set of reliable and self-consistent thermodynamic data for these slags, experimental determination of the activities of FeO in binary and ternary slags was carried out using the gas equilibration method involving CO-C02-Ar gas mixtures at steelmaking temperatures. The slag samples in Pt crucibles were quenched after the equilibration and subjected to chemical analysis. The thermodynamic activities of "FeO" in the slags were calculated from the experimental data. The results are incorporated into a thermodynamic description of silicate melts in the present laboratory. The model is based on a Temkin-Lumsden approach and is able to compute the thermodynamics of higher order systems from the lower order ones.

Jan 1, 2003

By Guozhu Ye, Mikael Lindvall

"Swedish iron ore contains about 0.1 %V. The vanadium is reduced to the hot metal in a blast furnace and oxidised to the slag in a converter. The high V-content, up to 5 % V, leads to a very limited external application of the steel slag in Sweden. Since 2004, MISTRA - the Swedish Foundation for Strategic Environmental Research has together with the steel and mining industry in Sweden and Finland initiated and supported a long term project aiming at efficient recovery of vanadium in the slag, and at the same time a useful slag product with low V-content. The proposed concept consists of a reduction step and a phosphorus removal step. This paper will highlight some of the results with focus on the various metallurgical reactors used for slag reduction, including results from recently performed pilot trials using a DC furnace for cotreatment of metallurgical slags and other wastes.IntroductionToday, less than half of the produced LD-slag in Sweden is recycled to the blast furnace as a lime source and the rest is temporarily stored inside the steel plant. The steel slags cannot be used externally due to its content of vanadium and free lime. As the slag storage area is limited, this has become a problem for Swedish steel producers. The disposition of the slag is also a great waste of a valuable vanadium resource. The current potential value of vanadium in the discharged steel slag annually amounts to roughly US$ 100 million. Currently, Swerea MEFOS is conducting an 8-year vanadium recovery project called VILD (Vanadium in LD-slag) aiming at efficient recovery of vanadium and at the same time producing a useful slag product with low V-content. The project is financed by MISTRA - the Swedish Foundation for Strategic Environmental Research and the steel and mining industry in Sweden and Finland. Various reactors and process options have been tested in the past 7 years, from 3 kg laboratory scale, 150 kg induction furnace, 3 MVA pilot DC furnace, 5 MVA pilot AC furnace, 5 tons Kaldo furnace, to full scale direct hot slag reduction in the industrial site (12 tons of slag). This paper will introduce the VILD-concept and review the experiences gained from these trials. The advantages and disadvantages of the different options will be discussed and concluded."

Jan 1, 2012

By L. G. Wiseman

The raw materials processed, highlights of technology used, and products produced at INCO's Copper Cliff Nickel Refinery in Ontario, Canada, are described in this paper. INCO's Bessemer matte separation process yields various nickel and copper products and intermediates. The latter presents the main supply of raw materials for the Refinery. Key features in the Refinery are Top Blown Rotary Converters and the INCO Pressure Carbonyl (IPC) process. Process improvements made since the commissioning of the Refinery in 1973 are also discussed. The Refinery produces a variety of nickel products, including nickel powders. Residue after carbonylation presents an important intermediate enriched in precious metals and cobalt that serves as feed to downstream operations for recovery of the residue's metal values. Also discussed are detection, measurement and control procedures which ensure safe operation.

Jan 1, 1988

By Zuoren Huang

The flowsheet of the hyd.rametallurgical zinc plant which is in use at Zhuzhou Smelters is described. The principal features of the process are fluid bed roasting, continuous calcine leaching, solution purification, zinc electrolysis, electrolyte cooling, and finally, the melting and casting of zinc forms. The Zhuzhou process for the flotation of silver from the leach residue collected on the Moor filters is described. The technical details of the process are outlined and the operating data are analyzed. The flotation facilities are described in detail and concentrate grades and recoveries are presented. The waelz process is used to concentrate In, Ge and Ga remaining in the leach residue after silver flotation. These elements subsequently are recovered by selective leaching in sulphuric acid, and details of this operation also are presented.

Jan 1, 1990

By I. Barin

The thermodynamics of cyclone smelting of sulphidic copper ores is described using as example the production of copper matte with 75 wt % Cu. Equilibrium calcualtions and material and energy balances show that an increase in process temperature from 1600 K to 1900 K results in the extensive transfer of minor elements such as As, Sb, Bi, Pb, Zn,.... to the gas phase. A pilot plant for carrying out the cyclone smelting process is described. Calculations of material and heat transfer for the reaction of ZnS show that the smelting reactions of sulphides in the cyclone take place very rapidly at high temperatures. The dissociation of the sulphides with subsequent oxidation reactions in the gas phase plays an important part in. the process and is mainly controlled by heat transfer.

Jan 1, 1983

By L. A. Harris

In the present study the open gradient magnetic separation' (OGMS) method has been used to beneficiate the -30 + 100 mesh fraction of two high volatile bituminous coals. The evaluation of the effectiveness of the magnetic separation for cleaning these coals is the subject of this paper. Coal petrography in combination with scanning electron microscopy (SEM) and x-ray diffractometry (XRD) were used to characterize the magnetically separated coal fractions. These analyses revealed that the majority of the pyrite and non-pyrite minerals were concentrated in the positive magnetic susceptibility fractions. The bulk of the starting samples (-80 weight percent) were located in the negative magnetic susceptibility fractions and showed significant reductions in pyrite and non-pyritic minerals. The magnetic separation appears to effectively split the samples into relatively clean coal and refuse.

Jan 1, 1981

By K. V. Sreenivas Rao

Solidification experiments have been conducted to study the effect of interface heat flux and air gap formation on cooling rate of the casting during solidification of Al-4.5wt%Cu alloy. The thermal history of the casting and mold during solidification is recorded using thermocouples connected to computer interfaced data logger. The measured temperatures in the mold are used as input to the IHCP (inverse heat conduction problem) algorithm for simulating multiple heat flux components at the boundary. It is observed that the filling effects induce spatial variation in the thermal field in the mold and casting regions and greatly influence the cooling rate of the casting. The study demonstrates the use of IHCP and in-situ measured thermal profile in analyzing the cooling rate and microstructure.

Jan 1, 2008

By D. J. Chaiko

Certain radionuclide ions (e.g., TcO4) exhibit unusually strong Affinities toward the polymer-rich phase in aqueous biphase systems generated by combinations of salt solutions with polymers such as poly(ethylene glycol) (PEG) and poly(propylene glycol) (PPG). Thus, aqueous. polymer ,phases could potentially be used to selectively extract these ions during pretreatment of radioactive tank wastes at Hanford. To help develop a fundamental understanding of the interactions between various ions and polymers in aqueous solution, interaction enthalpies between sodium -perrhenate and a random copolymer of PEG and PPG (UCON-50) were measured by microcalorimetric titration. An entropy compensation effect was observed in this system in which changes in enthalpic interactions were balanced by entropy changes such that the interaction free energy remained constant and approximately equal to zero.

Jan 1, 1999

By Thomas Niehoff, Yin Qing, Wei Zhongling, Liu Yongguo, Zhang Deliang, Tang Le

The gold ore of Shandong Gold Mining (Xinhui) was a refractory ore, which contained multi metallic sulfides (ZnS and PbS etc.) and carbonaceous. The gold ore concentrate came into leaching process and thickener and zinc replacement to recover gold. In order to improve gold recovery, the GOLDOX™ hydrometallurgy process was studied in Shandong Gold (Xinhui) by bench scale and 6 month plant scale test supported by Linde Gas. It was shown that the process promoted the leaching kinetics and improved gold recovery. The residue grade reduced 0.22 g/t in average after oxygen was applied. This indicates an operating profit increase 850,000 yuan/a in the plant. It was setting a good example for similar gold mine plant and would promote the oxygen application in Chinese gold mining industry.

Jan 1, 2015

By Corby G. Anderson

Today, with a stringent economic and environmental climate prevailing in the copper business, there is increased interest in evaluating new processing alternatives for production. Hydrometallurgical pressure oxidation of copper concentrates is one of the more viable approaches and several technological candidates have emerged. Of these, an overlooked but, ironically the first industrially proven methodology, utilized nitrogen species catalyzation in the oxidizing pressure leach system to produce copper via SX!EW. Given its many inherent process advantages, this may prove to be a feasible process alternative for the future. In this paper, the history of the system and its application to chalcopyrite concentrates will be outlined. In particular, a novel methodology for effective recovery of precious metals from chalcopyrite concentrates will be discussed. Finally, the perceived economics of this unique industrially proven process will be delineated.

Jan 1, 2000

By C. E. M. Meskers, U. Boin

"The increasing use of coated magnesium in consumer products results in creation of coated Mg scrap during product manufacture and after End-of-Life product treatment. Currently this material is generally not recycled, leaving a material resource unused. Closure of the magnesium cycle in a sustainable manner is necessary. In order to do so, the effect of coatings on the recycling process has to be quantified, predicted and minimized. For this purpose metrics have been developed, based on first principles supported by detailed understanding of the recycling process. The developed 3D metric enables quantitative assessment of the recyclability and links coating design, product design and recycling to each other in a visual manner. The parameters that form the metric can be measured and predicted, hence an engineering basis for Design for Sustainability of coated magnesium is provided.IntroductionEvery product progresses through the four phases of the product life cycle depicted by figure 1. In each phase residues are created. Their amount and composition is largely determined by the complex material combinations created/invented during product design in the manufacture phase. Compared to the ideal cycle the magnesium cycle is far from closed (fig. 2). Most noticeable is absence of the link between the EoL phase and raw materials production. A closed cycle only exists for class 1 scrap, which goes from the product manufacture phase directly to production from industrial material and returns to the manufacture phase as magnesium alloys. The four problematic streams are marked by ???. Coated semi-products are present in two of the four residues, namely in rejects and collected scrap. When these semi-products are recycled the amount and composition of the dross and salt slag residue is affected as well.During product design selection of the coating takes place, fixing the coating character¬istics and properties from this moment on for the rest of its life cycle. The choices made in the manufacturing phase are therefore critically linked to the recyclability of coated semi-products as well as the sustainability of the magnesium cycle as a whole. Sustainable closed life cycles, in which the quality of materials is preserved and residue creation and resource depletion are minimized, can be attained by selecting the appropriate alternative during product design. To realize this the effect of design choices on the life cycle and more specific the recycling process has to be known and quantified."

Jan 1, 2008

By Shadia J. Ikhmayies

"Nanocrystalline fluorine doped tin oxide (Sn02:F) thin films were produced by the spray pyrolysis technique (SP) on glass substrates at a substrate temperature T, = 450 ° C. The hydrated stannous chloride (SnClz.2H20) was used as a precursor and ammonium fluoride (NH4F) and hydrofluoric acid (HF) were used as the doping compounds. A comparison between the compositional, morphological and optical properties of the films obtained by using the two doping compounds was performed by using scanning electron microscope (SEM) observations, energy dispersive spectroscopy by X-rays (EDAX) and transmittance measurements. It is found that the films prepared by using HF have larger grain size, and higher fluorine content than the films prepared by using ~- In addition these films have higher transmittance and higher direct optical bandgap energy. These results are interesting for the use of Sn02:F as a forecontact in CdS/CdTe solar cells.IntroductionTin dioxide is an n-type, wide bandgap semiconductor (about 3.5 eV) and in the form of thin films, it is a transparent conducting material, characterized by high optical transmission (80- 90%) [l]. Sn02:F is the most widely used transparent-conducting oxide material. The transparent-conducting thin films of this oxide are used as electrodes in a variety of optoelectronic devices, as heat mirror coatings in 'smart windows' for buildings, in automobile and airplane windshields, in incandescent light bulbs, in flat-plate and concentrating solar collectors. Tin oxide and zinc oxide, in thin film configuration are technologically important materials because of their applications in photovoltaic cells [2].Among various dopants for Sn02, fluorine is often preferred, because fluorine doping results in films with high transparency and good conductivity [3]. By exploring the literatures, it was found that different sources of fluorine were used to produce Sn02:F thin fihns, among which are ammonium fluoride (NH4F) and hydrofluoric acid (HF) are the most used. Some researchers used~ [2, 4-7] and others used HF [3, 6-8] for doping Sn02 films. Gordillo et al.[7] used both of NH4F and HF and showed that the resistivity of thin films obtained by using HF was lower than that of similar films obtained by using NH4F by a factor of 2.2. They also found that the films obtained by using HF have more random orientations."

Jan 1, 2013