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By Hongli Wen, Guangkun Shen, Qiong Deng, Shoujian Huang, Min Gan, Xiaohui Fan

"Due to the low iron grade and high sulfur content, pyrite cinder is difficult to be directly used for iron-making. In this paper, technology of magnetic roasting -grinding and magnetic separation -acid leaching was put forward for reclamation of pyrite cinder. For pyrite cinder of TFe53.51%, S2.20 %, studies showed that good magnetic effect can be achieved at roasting temperature 650~7000, reducing atmosphere CO/(CO + C02) 10~20% and roasting time 10~30 minutes. In separation conditions of grinding size -0.045mm accounting for 96.09% and magnetic field intensity of 1240 GS, iron concentrate of TFe64.81 %, S0.18% and iron recovery rate 91.44% was achieved. Acid leaching was studied to strengthen desulfurization. Results showed that high-quality iron ore concentrate of TFe66.3 l %, S0.10% was obtained under the conditions of hydrochloric acid mass fraction of 5%, pulp density of30%, leaching temperature of70? and leaching time of2 hours.IntroductionPyrite cinder is produced as a by-product of sulfuric acid industry [1] Domestic production is more than 12 million tons every year and occupied area is over 10 million square meters [2,3]. The pyrite cinder outdoor not only pollutes air but also damages surrounding surface [4] It after treatment used for iron-making is an ideal reclamation approach for its rich iron which is commonly 40-60% [5]. But pyrite cinder gets low utilization for its low iron grade and high sulfur content in China [6]. Therefore, comprehensive utilization of pyrite cinder has profound significance to environmental protection and the development of domestic iron and steel industry."

Jan 1, 2013

By Marc Verhaege

The effluent under investigation results from a catalic oxidation unit in which paraxylene is oxydised to terephtalic acid. The solution contains cobalt and manganese as their acetates in a concentration range of 0,4 - 1,2 g/I of cobalt and 0,8 - 2,4 g/l of manganese. Before being fed into the main waste stream treatment unit of the plant it is advisable to apply a petreatment step in which both metals are eliminated to a great extent from this effluent. Conventional treatment is done by precipitation of both metals either through pH increment with a base or by adding a suitable reagent producing insoluble species. The aim of this study was to look for a treatment (elimination of both metal species) in which no sludge or precipitate is formed.

Jan 1, 1995

By Shaohua Ju, Feng Jiang, Chuanhua Li, Jinhui Peng, Libo Zhang

A T-junction microchannel is proposed to overcome the existing problems in conventional solvent extraction of indium from zinc hydrometallurgical process. Experiments were performed to separate In3+, Fe3+ and Zn2+ from sulfate solutions using Di-(2-ethylhexyl)phosphoric acid (D2EHPA) as the extractant. The effect of parameters such as pH, microchannel size and contact time on the extraction behavior of In3+, Fe3+ and Zn2+ was investigated. At contact time of 2.52 s and initial solution pH of 0.48, the extraction efficiency of In3+, Fe3+ and Zn2+ was 99.13%, 8.31% and 2.45%, respectively and separation factor of In3+/Fe3+ and In3+/Zn2+ were almost 1229.54 and 4864.98, respectively. Then, the loaded organic phase was stripped in T-junction microchannel. At contact time of 33.6 s, 99.64% of stripping efficiency of In3+ and stripping equilibrium were reached, while concentration of Fe3+ and Zn2+ was lower than 0.01 g/L with good separation of In3+ from Fe3+ and Zn2+.

Jan 1, 2016

By Yuzura Sato

Viscosity has been measured for various molten binary alloys of nickel with iron, cobalt and chromium in order to clarify the behavior of viscous flow of molten nickel alloys. The entire concentration range for iron and cobalt and 0-67at% of chromium content were studied. The measurement method was an oscillating cup viscometry using an alumina crucible that was precisely machined. The temperature was up to about I 880K for all the measurements. The results represented good Arrhenian relationship although some measurements included overcooled temperatures. The isothermal viscosities increased monotonously with an addition of iron and chromium into nickel. The addition of cobalt increased after stationariness. The isothermal viscosities showed concave curves. Activation energies increased monotonously by adding all the elements into nickel. These phenomena were considered to be related to the thermodynamic properties 'such as the heat of mixing and the structures of mixture melts.

Jan 1, 2003

By W. E. Wallace, J. A. Warren, D. Josell, D. Wheeler

"We present the results of experiments and modeling of flip-chip geometry solder joint shapes under shear loading. Modeling, using Surface Evolver, included development of techniques that use an applied vector force (normal and shear loading) as input to determine a vector displacement of the pads connected by the solder joint (standoff height and misalignment). Previous solutions solved the converse problem: fixed displacements used to determine required applied force. Such solutions were inconvenient for applications, where the applied force (chip weight) is known. Also, for geometric and materials studies of solder joint shapes involving multiple parameters, determining the equilibrium displacement from applied force by bracketing solutions could become computationally expensive. Measurements of solder joint standoff height and misalignment as functions of the applied force (normal and shear), solder volume and pad diameter are presented. Experiments were carried out for solder ball diameters from 0.38 mm (0.029 mm3 volume) to 0.15 mm (0.0019 mm3 volume) on pads of diameter 0.64 mm and 0.35 mm. Fitting of simulation to experimental results gave optimized values for the contact angle and surface tension of the solder which were consistent with measured and literature values. IntroductionIn packaging technology flip-chip has become an important method for attaching semiconductor devices to substrates. Generally, the chip and substrate are bumped with solder and then the chip is flipped onto the substrate and the solder reflowed to form conductive interconnects. An epoxy underfill is normally flowed between the substrate and chip to reduce the thermal fatigue on the solder joints. A flip-chip assembly is illustrated in Figure 1.In flip-chip applications, the use of an integrated underfill/solder bump system [1, 2) removes an extra process step, namely infiltration of the underfill. However, the presence of an underfill will retard the self-alignment of the flip-chip. A first step in understanding and predicting this retardation is to develop a model to describe normal and lateral force-displacements curves when underfill material is not present. At this stage it is unclear whether static surface tension theory is sufficient to describe a complete model for flip-chip realignment even without underfill."

Jan 1, 2001

By G. H. Khoe

Neutralisation of acid uranium mill tailings with lime or other alkaline materials is usually practised to reduce the dissolved concentration of heavy metals and radio nuclides. Computer modelling of this process was carried out using the geochemical equilibrium code MINTEQA2. Computed dissolved metal and sulfate concentrations were compared with laboratory-based experimental data. It was found necessary to include the modelling of adsorption of trace metals (such as uranium and lead) by the precipitated ferric hydroxide in order to obtain acceptable concentrations in the neutralised liquors. There were limitations of the modelling exercise due to important aspects which were not addressed or properly accounted for such as chemical reaction kinetics and the effect of high ionic strength. These are discussed in the paper.

Jan 1, 1991

By N. B. Gray, I. F. Taylor

"Gas injection to promote chemical reactions or mixing is a feature of many metallurgical processes. Often the aim of gas injection is to bring about a chemical reaction between the gas and liquid but most of the past physical and mathematical modelling work has ignored the influence of such reactions. In the work reported here, cold model studies have been conducted in which gas reacts with the liquid into which it was injected. The rate of liquid mixing has been measured as an indication of the mechanical energy transfer. It has been found that gas generated chemically within the liquid is significantly less effective at promoting mixing than the equivalent volume of inert gas. The relative ineffectiveness of chemically produced gas is thought to be due to smaller bubble sizes in comparison to the inert gas case. Small bubbles characteristic of chemically generated gas move with low slip velocities relative to the liquid and lead to different turbulence generation mechanisms.IntroductionIn processes such as steelmaking, copper conversion, bath smelting and ladle steel finishing gas is injected into liquid metal where it reacts chemically or simply serves as a source of agitation. An understanding of fluid flow phenomena in such situations is an essential pre-requisite to the calculation of process intensity and the optimisation of vessel productivity. Traditional physical cold modelling approaches to prediction of liquid flow in such situations are now often augmented by the techniques of computational fluid dynamics. Even with the availability of numerical modelling techniques cold physical models continue to have an important role for validation because it is generally difficult to obtain quantitative data from high temperature processes.Almost all previous cold modelling work has been based on the injection of an inert gas into water or some other non-reactive liquid. Such models do not include the significant increase in gas volume inherent in some processes. For example the oxidation of carbon in steelmaking leads to a twofold increase in molar gas flux through the reaction:"

Jan 1, 1996

By C. E. Abbey

Cobalt, iron and manganese play various roles in copper electrowinning using lead–calcium–tin alloyed anodes. Cobalt catalyzes electrochemical water decomposition resulting in lower anode potential and reduced corrosion rates. Iron reduces cathodic current efficiency, but is used to reduce higher oxidation states of manganese that oxidize organics in solvent extraction. Manganese also produces anode scale and is generally considered a problematic impurity. The effect of the combined interaction of these three metal ions on the anode potential has not been quantified yet. The current work used a three factor, two level, three replicate central composite design of experiments to analyze the effects and potential interactions among cobalt, iron and manganese. The experiments consisted of chronopotentiometric analysis to assess anode potential after 24 h of operation. Higher [Co], lower [Mn] and either high or low [Fe] yielded lower anode potentials. Two regression models were developed to predict anode potential as a function of [Co], [Fe] and [Mn]. A method to estimate electrical energy consumption for copper electrowinning is also presented.

By Kiyoshi Shibata

A new assessment model has been proposed for metal production and its recycling system. The model consists of three processes, smelting of ore, cascading and upgrading of metal scrap. The present approach is to assess the total energy consumption of the system, by introducing two equations for describing the relationships between critical impurity content and the mass of production or scrap recycling. The total energy consumption in the system can be described as a function of recycling rate and performance of the upgrading process. The present model suggests that the impurity removal efficiency and yield in the upgrading process are essential to reduce the energy consumption in the systems. Especially, such points should be explicitly controlled in recycling of aluminum. The potential capability of this model was also discussed by obtaining several quantitative information required for the process design and the operational control of beneficial recycling of metals.

Jan 1, 1998

By Xu-ling Chen, Qian Li, Yong-bin Yang, Zhao Jing, Tao Jiang, Guang-hui Li

"It is generally known that alkali metals are harmful to blast furnace production resulting in aggravating RDI of sinters, abnormal expansion of pellets, deteriorating blast furnace lining, etc. Sinters regarded as dominating burden of blast furnace are determined as the main source of alkali metals. In this study, the removal behavior of potassium and sodium oxides by pre-reduction sintering during the sintering process was studied. The removal ratio ofK20 and Na20 was greatly influenced by coke powder content, carbon species, coke powder adding ways, additive and so on. Under the conditions of carbon rate 12% and 5% dosage of CO supplied in the sintering process, the corresponding removal ratio ofK20, Na20 was 69.00% and 32.79%, and metallization ratio could reach 4.65%. This technology provided a novel process for reducing the content of alkali metals in sinters and dramatically improving the quality of blast furnace burden.IntroductionSinter is the main iron-bearing charge of blast furnace for iron-making in China, making up about 80% of the total burden; therefore, its quality has a significant influence on the quality of pig iron and blast furnace operation. Research and practice of numerous years prove that potassium and sodium coming from ores are brought into blast furnace and upgraded, which is one of the essential reasons that lead to blast furnace nodulation and influences its strength. Currently, effective flow sheet to remove potassium and sodium is weak magnetic separation-intensive magnetic separation-flotation [l], while iron ore concentrate is still ofhigh levels of potassium and sodium. As sintering process is also not effective to remove potassium and sodium, blast furnace in China is of high alkali burden, e.g. it reaches 5.6-6.2kg/tFe in Baotou iron making plant, which is greater than international tolerated level of2.55kgltFe [l]."

Jan 1, 2013

By Chengyi Ding, Xuewei Lv, Changyang Ji, Rende Zhang, Xiangwei Zheng

Inexpensive and high-quality sinter has an extraordinary position in iron making, and there are many factors influencing the sintering. This research takes the basicity and coal dosage as research subjects to do the experiments based on cost analysis with sinter pot experiment system. Linear program is taken to make the schemes of ore blending. During the experiments of changing basicity from 1.6 to 2.3, the properties and microstructures of the sinter are studied. It comes to a conclusion that increasing the basicity is beneficial to sinter quality but leads to higher cost. To further ascertain the cost of sinter and the potential of saving coke, the work of improving coal dosage is taken on the basis of experiments of changing basicity. Through analyzing the results, a formula (Y=1849+261.1R-130.6C) is proposed which indicates the relation among the cost, basicity and fixed carbon content. And it works well for actual production.

Jan 1, 2015

By Chris P. Pistorius

Over the past few decades the carbon intensity of ironmaking and steelmaking has been reduced considerably through improved efficiency in blast furnace ironmaking, partial replacement of coke with less carbon-intensive fuels, and increased use of scrap and direct-reduced iron in steelmaking. To evaluate possible further reductions in carbon intensity accurate process information is needed. A preliminary test of the fidelity of publicly reported data as a source of process information is reported here. The sources are industry roundups of electric furnace furnace steelmaking and blast furnace ironmaking (published by the Association for Iron and Steelmaking Technology), and data recorded by the Environmental Protection Agency under the US Greenhouse Gas Reporting Program. From a comparison for an integrated steelmaking plant and an electric furnace furnace plant, it appears that the values from the two data sources are consistent. The comparison does rely on process details such as the quantitative relationship between injected oxygen and carbon emissions in electric furnace steelmaking.

By T. Shoji

"The human history is characterized by social development based on mineral and energy resources, and many conflicts to take the resources by power. This is shown by not only world wars but also many local conflicts as well as international supremacy.IntroductionThe world population after B. C. 10000, which is summarized in several papers, is approximated by four straight lines on a semilogarithmic diagram as shown in Figure 1 [l]. The annual rates of increasing are 0.0041, 0.071, 0.53, and 1.85 % from the old and young periods. The boundaries among four periods are approximately B. C. 4600, AD. 1670, and 1930. The start of the second period seems to correspond to the beginning of agriculture and cattle breeding. Precisely speaking, the usage of natural energy resources such as woods and domestic animals already began, but is inferred to have become common after the age. The third and fourth periods are characterized by the common usage of coal and oil, respectivety. Not only energy resources but also mineral resources including gold, copper, iron and others are also important for the human history.Mineral and energy resources have supported the development of the .human civilization, and have caused many conflicts because of this reason. Every day newspapers report conflicts, such as Chechnya, East Timor and Ache. We can easily point out the facts that the conflicts closely relate to mineral and energy resources. Groznyj, Capital of Chechnya, is located on the western margin of Caspian oil field. Many mineral deposits occur in Kavkaz Mountains running south of Chechnya. Subsea oil fields occur in Timor Gap located between East Timor and Australia. Ache is also one of oil fields in Indonesia. It is very difficult to state present conflicts independently of a political view of point. For this reason let us try to historically review the relation between mineral and energy resources and international domination and conflicts [2] based on many papers [3]."

Jan 1, 2000

By Jr. Langhans, J. S. McPartland

"The presence of zinc in cyanide solutions is generally thought to not have an adverse effect on precious metal recovery or recovery rate by heap leach processing. However, analytical interferences of zinc in solution can cause problems in accurately determining and controlling cyanide concentration in the leach solution, leading to increased cyanide consumption. Analytical methods and the chemistry of cyanide in the presence of zinc are reviewed. The effects of solution pH and zinc concentration on the free cyanide determination were evaluated in detail. Use of the standard silver nitrate titration and a modified titration method for controlling cyanide concentration during heap leaching were investigated experimentally. The practical implications of cyanide heap leaching in the presence of cyanide soluble zinc minerals are discussed.IntroductionThe presence of zinc in precious metal cyanidation circuits is not uncommon. Zinc can be introduced into cyanide leach solutions through dissolution of various zinc minerals1>, or through the use of a Merrill Crowe (zinc precipitation) circuit. Zinc minerals typically occur infrequently and in low concentration in gold ores, but are more abundant in silver ores. Merrill Crowe systems are most commonly employed for recovery of precious metals from solution for relatively high silver ores. It is desirable to control the amount of dissolved zinc in a cyanidation circuit for several reasons. Excessive zinc build-up in cyanide leach solution can, under certain circumstances, inhibit precious metal dissolution and adversely affect solution recovery systems. Additionally, high zinc concentrations can lead to excessive in-process cyanide inventories and potentially, to higher cyanide consumption"

Jan 1, 1999

By José Brant, Douglas Torres, Rogério Navarro, Rodrigo Souza, Eduardo Brocchi

The steelmaking process requires the input of ferro-alloys to implement the adjustment of some elements composition in the final product. In the particular case of stainless steel production, the high carbon FeCr alloy stands out as one important precursor. However in the production of this material a certain quantity of fine powder with remarkable chromium and carbon content is also generated, which, in turn, could be processed through alkaline roasting in order to selectively recovery this element in a subsequent aqueous route. In the present work, this process is investigated, using excess of NaOH as oxidizing agent, and H2O2 for precipitating chromium as Cr(OH)3, which is next calcinated to Cr2O3. According to the results, the global achieved recovery has shown to be around 98%, suggesting that the proposed route can be seen as a potential process for chromium oxide production from the mentioned fine powder.

Jan 1, 2015

By Vinicius Alves Gomes, Jean Igor Margem, Thallis Cordeiro, Frederico Muylaert Margem, Roberto Faria Jr., Sergio Neves Monteiro, Marina Rangel Margem

Natural fibers are attracting the interest of engineering sectors owing to specific advantages such as lightweight and lower cost as well as for their inherent condition of being renewable, biodegradable, recyclable and neutral with respect to CO2 emission. In particular, the fiber extracted from the malva plant stem is nowadays recognized as one of the strongest lignocellulosic fibers. However, the thermal properties of the malva fibers have yet not been fully investigated. The present work had as its objective to investigate, by photoacoustic spectroscopy and photothermal techniques the thermal properties of diffusivity, specific heat capacity and conductivity of a pressed malva fibers sample. The results revealed that these fibers showed a superior thermal insulation capacity.

Jan 1, 2015

By Lei Zhang, Shining Chen, Lina Wang, Pu Liu, Benquan Fu, Jiannyang Hwang

A PFS(polymeric ferric sulfate) coagulation-photocatalytic oxidation technology was used for advanced treatment of coking wastewater from secondary biological treatment. Effects of some key factors on TOC removal rate were investigated, and the results were compared with those of the common photocatalytic oxidation technology under the operating parameters of the photocatalytic oxidation defined. Single factor experimental results showed that TOC removal rate could reach 81%, when optimal operating conditions were as follows: TiO2 loading: 4.0g/L, irradiation time: 4h, initial pH is 5.1and PFS dosage:700mg/L. PFS coagulation and photocatalytic oxidation have synergistic effect, which is meaningful for highly efficient treatment of coking wastewater

Jan 1, 2015

By Xiaoyan Xiang, Wenqiang Yang, Wentang Xia

Magnesium aluminate spinel is widely used in the metallurgical industry as refractory material, however, natural magnesium aluminate spinel is rare and most of the magnesium aluminate spinel is synthetic. The traditional synthesis of magnesium aluminate spinel often needs high temperature, which leads to more energyconsumption. In this article, solid phase sintering process was employed to synthesize magnesium aluminate spinel, in which, magnesium and aluminum oxide were used as raw materials and magnesium and aluminum powder were used as composite additives. The mass ratio of magnesium and aluminum on the effect of synthesis of magnesium aluminate spinel and the characteristic of the synthesis at different temperature and time was discussed. Experiment found that the synthesis temperature was observably lowered when the addition of magnesium and aluminum was 2.0% and 1.0% respectively.

Jan 1, 2016

By Jyri Talja, Shaolong Chen, Hannu Mansikkaviita

"Drying (water removal) prior to smelting is always economically feasible. Unnecessary heating of vapour can thus be eliminated resulting in savings of5-15 MUSD every year.Thermodynamically removal of one ton of water out of copper concentrate at 100 °C (with 10 % moisture) requires approximately 3150 MJ/tH2o, consisting of heating of the water (377 MJ), heating of the concentrate (509 MJ) and water evaporation (2260 MJ). This is quite independent of the selected drying technology. In reality some more heat is needed as higher temperature is practiced to enhance the drying performance and to reduce the equipment size.Major nominator in drying energy efficiency is amount of gases, which depends greatly on the drying technology. Dryers based on direct heating with fossil fuels have high gas flow rates, and thus they require additional energy of about 1400-1600 MJ/tH2o, compared to indirect modemsteam drying at 250-400 MJ/tH2o.Significant benefits in energy consumption (900-1300 MJ/tH2o) with additional potential for a bonus profit of 2-4 MUSD/y year, together with full elimination of some 40 000 tpy CO2 per mid-size dryer is available by selecting sustainable, energy efficient steam drying.IntroductionRemoval of water from the concentrate is very energy intensive thus having a significant environmental impact. However, drying prior to smelting is always economically feasible and very often viable also from the perspective of process operations. This environmental impact of drying can, however, be decreased or even fully eliminated with proper selection of the drying technology.Energy incorporated in drying consists always of a number of phases like liquid (water), solids (concentrate) and gases (water vapour, purging I dilution air, combustion gases). Each phase is heated to a specific temperature during the drying process.Heating of water, heating of the concentrate and water evaporation consumes more or less the same amount of energy despite of the drying technology (3150 MJ per ton of water). In conventional drying this amount of energy is achieved by combustion of fossil fuels wirg subsequent CO2 emission. Alternatively, chemical energy derived from sulphide smelting can be utilized in a form of steam thus generating zero emission ofCO2, in modem steam drying."

Jan 1, 2012

By Peter G. Smith

Tri-calcium aluminate (TCA) is a dominant alkaline component of the red mud residue from the Bayer process. A method being considered for industrial implementation partially neutralizes the residue by contacting it with gaseous CO2. This paper outlines the chemistry of CO2neutralisation of TCA under conditions relevant to the treatment of Bayer residue. CO2 neutralisation of the liquor is fast. It results in the formation of amorphous aluminium hydroxide and dawsonite that agglomerate together. Neutralisation of solid TCA is slower and leads to the formation of calcite, dawsonite and amorphous aluminium hydroxide. The dissolution of TCA in partially neutralised slurries causes pH reversion. However the carbonated solutions contain a store of bicarbonate that can supply aqueous carbon dioxide to complete the transformation. The pH at which the carbonation is carried out will affect the degree of TCA transformation during the carbonation process. In particular, if the pH of the carbonation is too low (near 7.0), calcite precipitation is inhibited and the degree of transformation is low. Controlling the carbonation pH helps to optimise the neutralisation process.

Jan 1, 2003