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By Xun Hu, Jian Pan, Hongbin Yu, Deqing Zhu, Yanhong Luo

Lump ores are one kind of important burdens for blast furnace (BF), their metallurgical properties have significant influence on BF performance. In this paper, the relationships between the mineralogy of five natural lump ores and the metallurgical performance have been studied. The mineralogy study includes mineral compositions, microstructure and porosity, and the metallurgical performance covers reducibility index (RI), low-temperature reduction degradation index (RDI) and decrepitation index (DI). The results show that the complex lump containing hematite, and goethite has better overall metallurgical performance. For single lump, the RI of goetihte ores is higher, the RDI and the DI is strongly influenced by porosity. The hematite and magnetite ores have good anti-decrepitation and anti-RDI, but generally the RI is lower due to lower porosity, and the RI is related to the grain size, the smaller grain size is, the better reduction will be.

Jan 1, 2015

By Qian Li, Li-chen Hou, Yong-bin Yang, Tao Jiang, Jian-jun Hu, Bing Xu

Extraction of gold from refractory gold concentrates usually requires an oxidation step to remove arsenides、sulphides and carbonaceous matter. In this investigation, the gold concentrates were two-stage roasted under different atmospheres and temperatures. Results indicated that at the first stage, under neutral atmosphere, the removal rate of arsenic increases as the temperature rises. Under the oxidizing atmosphere, with the increase of temperature, arsenic content in the residued calcine increases, in addition, the volatilization of arsenic is also affected by the oxidation of carbon that generated CO, which is advantageous to the decomposition of arsenate decomposition. At the second stage of roasting, it is the higher temperature and stronger oxidizing atmosphere, the faster sulfur and carbon oxidated rate is, but at the same time, the calcine appears the phenomenon of consolidation because of the phase of silicate compounds generate.

Jan 1, 2015

By Z. Y. Xie

The visualization techniques were employed for the analysis of computer simulation studies of dislocation core structure in ordered alloys. Atomistic computer simulation was used for the study of the local configuration of the material in the vicinity of the dislocation. Stresses were applied in the simulation in order to study the necessary stress level for the dislocation to move and onset plastic deformation of the material. The results were analyzed in terms of the strain tensor as a function of the position (x, y) in the material with the dislocation located at (0, 0). Various visualization packages are used to plot the invariants of this strain tensor and to visualize the changes that the dislocation core undergoes under stresses until it finally moves.

Jan 1, 1993

By Shaolong Chen, Carl-Gustav Berg, Hannu Mansikkaviita

Kumera Steam Dryer has been developed particularly for nonferrous metal concentrates with steam as heating source generated from waste heat boilers. Its unique structure enables the dryer to work at high capacity, up to 240 t/h, and high availability, over 95%. With half a century of engineering experience, and more than twenty industrial steam dryer installations worldwide during last 15 years, Kumera has demonstrated significant benefits of the steam drying technology in terms of energy efficiency and emission reduction to the end users. The dryer of this type can also be applied for other suitable mineral materials.

Jan 1, 2015

By Xuewei Lv, Guibao Qiu, Jiaqing Yin, Chenguang Bai

"The iron ore sinter is one of the main raw materials for the blast furnace (BF) process. In the production of iron ore sinter, the cooling speed of the sinter determines its quality. In addition, the heat recovery devices are installed in the cooling machine for energy saving. The cooling parameters like gas flow rate and the size of sinter should be optimized for getting the gas with a higher temperature and a good quality of sinter simultaneously. In this study, the commercial simulation software COMSOL was used to establish a model for simulating the cooling process of the iron ore sinter. Moreover, three different gas flow rate (1.5, 3, 5m/s) and three different diameter of sintered particles (50, 70, 100mm) were investigated with the model. As a result, in certain porosity, a higher cooling speed was achieved when smaller size or larger gas flow rate was used. And lower gas flow rate was beneficial for the heat recovery. The model could intuitively present the exchange of heat between the sinters and air, as well as the flow and temperature fields during the cooling process.IntroductionIron ore sinter plays a great role in iron and steel industry for many Asian countries such as China, Japan and India. As a part of the sintering procedure, the impact of cooling process on the quality of iron ore sinter couldn't be neglected. On the other hand, the massive iron ore sinters which were at high temperature contain extremely large amount of heat. However, it was reported that there's very few of them recovered in China with an average recovery rate of nearly 10.5% at 2004 [1]. Thus, more reasonable cooling procedure should be developed to get high quality product and heat recovery rate simultaneously."

Jan 1, 2011

By Guohua Bai, Yuanbo Zhang, Guihong Han, Zijian Su, Daoyuan Zhang

"Specularite ores have poor hydrophilicity and ballability as well as inferior high-temperature reactivity, which restrict the large-scale application of them in the pelletizing and sintering production. Modified humic acid (MHA) organic binders are firstly used for pellet preparation from specularite in this paper. The results show that the drop strength of green pellets is 3.7 times/0.5m and compression strength is 12.5 N/P by using 1.0 wt% MHA as binder. Under the optimal experimental conditions of preheating temperature 980 °C, preheating time 12 min, roasting temperature 1280 °C and roasting time 10 min, the preheated pellets have the compression strength more than 400 N/P, and that of roasted pellets is 2747 N/P. The strength of finished pellets meets the requirements of blast furnace iron-making. MHA is a kind of more effective organic binder for specularite pellets compared with the inorganic bentonite.IntroductionAcid Pellets have advantages of good strength, uniformity particle size, high iron grade and good reducibility, which can be used as high-quality burdens for blast furnaces [1]. With fast development of Chinese iron and steel industry domestic magnetite concentrates with high grade of iron and good firing performances become shortage.Imported specularite ores have advantages of low price and high grade of iron (generally above 67 wt%), so the application of them in pellets is an effective way for sustainable development of pellet industry in China. However, the specularites have not been utilized in pelletizing and sintering at present because of the poor ballability and high-temperature reactivity [2, 3]. Most of the pellet plants use bentonite as binders, the amount of which is about 2~3 wt%. The pellet production practice shows that 90 wt% bentonite is still residual in finished pellets and reduces the iron grade [3]. Developing a new organic binder instead of bentonite is very important to the high-quality pellet production. On one hand, the consumption of bentonite is obviously reduced, resulting in decreasing the ironmaking coke ratio and slag discharge; On the other hand, the iron grade of finished pellets are improved, which brings the benefit for the ironmaking production."

Jan 1, 2011

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 Cecil Harriss

Philip Environmental Services Corporation's (Philip's) innovative fluidized bed thermal desorption system recovers mercury from contaminated soil. Referred to as the Thermal Recycling System, Philip has constructed a mobile thermal desorption system that has a processing rate up to five tons per hour. The system includes a continuous-feed system, all radiant heat, inert gas atmosphere, hot gas filter, two-stage cooling, and a water treatment system. Based on treatability studies, the processed soil can meet cleanup objectives as low as two milligrams per kilogram and passes the mercury toxicity characteristic leaching procedure test.

Jan 1, 1996

By Chai Li-yuan

The anodic behavior of AZ31 magnesium alloy in NaOH alkaline solution was investigated in this paper. The effects of anodizing parameters, such as applied current density, concentration of NaOH and temperature of the solution on the formation, structure and surface morphology of the anodic films were also studied. The formation of the anodic film was analyzed by analyzing the anodic polarization curves, the potential-time curves and XRD, SEM graphs of samples obtained at different anodizing time. The results of corrosion resistance tests, XRD and SEM observation showed that the temperature greatly affected the formation and anti-corrosion property of the anodic film, but the concentration of NaOH not. The film with best anti-corrosion resistance was obtained at applied current density of 10mA/cm2, 353k in 1mol/l NaOH solution.

Jan 1, 2006

By Gaifeng Xue, Xiaohong Xu, Meng Liu, Yijie Song, Guotao Xu, Jixiong Liu

BN (Boron Nitride) based composites were prepared with hot-pressing by using h-BN as main material in ceramic preparation process. The relative density, bending strength, vickers’ hardness, thermal shock resistance, thermal expansion coefficient, thermal conductivity, phase composition and microstructure were tested and analyzed by using modern testing technology. The results indicate that the best formula is B, the relative density is 97%, the bending strength is 260 MPa, the hardness is HV5 343kg/mm2, the thermal expansion coefficient is 2.8×10-6℃-1, the thermal conductivity is 22 W/(m.K) and have no crack after thermal shock for 20 times by water cool. XRD analysis indicates that the main phase compositions are h-BN, β-Si3N4 and sialon. SEM studies show that the grains wrapped up by solid solution.

Jan 1, 2015

By Denise Crocce Romano Espinosa, Andrea Moura Bemardes, Jorge Alberto Soares Tenorio, Daniella Cardoso Buzzi, Tatiana Scarazzato

"In copper plating processes, a fraction of raw materials are incorporated to the final products, while other portions are discarded as effluents. In this study, the application of electrodialysis (a membrane treatment process) was studied for treatment of wastewaters from cyanide-free strike baths, in order to reuse the components of this bath: copper and HEDP. The synthetic solutions studied consider 1 % of ion concentration of the bath used in this process, simulating the rinsing waters to be discarded. The electrodialysis allowed a percentage extraction up to 73% of copper ions and 72% of HEDP from the effluent. Complexes formation between the acid and copper indicates the possibility of recovery of components in the same compartment, obtaining a concentrated solution of these substances that can be reinserted in the process, for compensating drag-out losses. A diluted solution is also obtained, that can be reused as water in rinsing tanks.IntroductionIn metal finishing industries, contaminants in wastewater and the type of treatment required are determined according to the type of operation [l]. Generally, electroplating industries employ conventional wastewater treatments, e.g. oxidation of cyanide and chemical precipitation. This stage promotes reactions with soluble compounds to produce an insoluble precipitate, removed by physical separation. The sludge is dried by press-type filters [2].In this manufacturing sector, part of the raw materials are discarded as hazardous waste. The cost of discarded compounds and the treatment and disposal of waste may compromise profit margins. In addition, water consumption per unit of production stimulates the development of methods able to recover and reuse the largest possible amount of water [3].In some plating processes, cyanide-based substances are used as complexing agents and as raw materials in form of metal salts [4]. However, the toxicity associated with cyanide has been promoting research for the development of new raw materials in plating processes.A study conducted in Brazil [4] evaluated the modification of a commercial cyanide-free bath for processes of copper coating on Zamak. In the performed study, a new alkaline copper bath was formulated using l,hydroxyethane-1,1-diphosphonic acid (HEDP), an organic compound known for forming stable complexes with metal ions.As results of the study, the operational conditions and the formulation of a bath to obtain adherent, uniform and bright layers were established (Table I) [4]."

Jan 1, 2014

By Shi Guan-Yong, Niu Li-Ping, Dou Zhi-He

"In the preset work, the viscosity model (named modified KTH model) proposed by Sichen Du and S. Seetharaman et al and extended by Shu Qi-feng was applied to the ESR slag systems. A correlation to predict the viscosities of CaF 2-(CaO)-Al203 slags using interaction coefficients of different cations in the presence of oz-and viscosity interaction coefficients between oz-and F in the presence of different cations has been developed. The interaction coefficient between oz- and F- in the presence of Al3+ was determined from the experimental data as shown in known literatures. The good agreement between the calculated viscosities and the experimental data in the CaF2-(CaO)-Al203 systems has indicated that this approach can be successfully employed to predict the viscosities of ESR slags.IntroductionReliable viscosities data of high-temperature slag melts are important for the modeling and design of high temperature metallurgical processes. Although a number of experimental measurements have been carried out, the available viscosities data is still scarce compared to the needs of today's technology, especially in the case of complex melts. In process simulations, the needs of viscosity descriptions for complex systems which could enable the extrapolation of the data as functions of temperature and composition is strongly felt today."

Jan 1, 2013

By Minting Li, Hailong Yang, ChangWei, Cunxiong Li, Gang Fan, Xingbin Li, ZhiganDeng

The filtration problems on acid leaching sludge of high silicon zinc ore have been paid extensive attention in zinc hydrometallurgy. It was found that soluble silica can be effectively converted into silica precipitate with good settling, filtration and washing properties, and the filtration rate can be in excess of 800 L/m2 · h under certain leaching conditions. According to investigating on the filtration rate, viscosity and concentration of silica of leaching sludge or liquor, the filtering temperature can tremendously improve the filtration property of pulp. At the same time, the experimental data indicated that the viscosity of leaching liquor was the key factor influencing filtration property of leaching sludge.

Jan 1, 2016

By Jun Chang, Jin-hui Peng, Jing Chen, Li-bo Zhang

The leaching of indium from refractory zinc oxide flue dust(ZOFD) is attempted to utilize microwave sulfating roasting process, followed by water leaching. The ZOFD and roasted product were characterized by XRD and SEM/EDS analysis. The effects of various roasting parameters, such as roasting temperature/duration, the proportion of sulfuric acid, as well as the leaching parameters such as the leaching duration and liquid/solid ratio, were assessed. The results indicate that nearly 97% of indium could be leached under the following conditions: mass ratio of concentrated sulfuric acid to ZOFD to be 0.5, roasting temperature of 150 ℃ and duration of 1.5 hours; while the optimal leaching conditions hold at temperature of 25 ℃ for 1 hour, with 4:1 of liquid/solid ratio. The indium leaching rate by the microwave roasting increased by 8% as compared with the conventional roasting process under identical conditions.

Jan 1, 2015

By Fatma Arslan

Alada (Kayseri-Turkey) lead-zinc sulfide-oxide ores contain 10.17% Pb, 10.98 %Zn, 164 g/t Cd and 57 g/t Ag. During the laboratory scale flotation tests of these ores, it was found that almost all zinc was remained in the tailings that contain 12.31% Zn, 1.35%Pb, 198.3 g/t Cd, and 22.3%Fe. Three different methods were studied such as basic (NaOH) leaching, roasting+acidic (H2SO4) leaching and direct acidic (H2SO4) leaching for recovering metals that these tailings contain. In the direct acidic leaching, which gave the best results, dissolution efficiencies of 91.5% zinc, 78.2% cadmium, and 14.3% iron were reached at the optimum leaching conditions while Pb remained in the leach residues and the acid consumption was 422.3 kg/ton of tailings.

Jan 1, 2006

By Bryn Harris

Much has been written over the past twenty years on the removal and chemical stabilization of arsenic from metallurgical process solutions. This paper reviews again the latest developments in this field, and concludes as before that the high-iron arsenical ferrihydrites, together with the high temperature arsenic minerals, scorodite and Type II, remain as the best and most viable vehicles for industrial control and disposal. However, a cautionary note is introduced, in that chemical environments cannot be considered in isolation, and that cogniscence has to be taken of microbiological activity in determining the disposal method. Data are also presented on a survey of industrial practice, which shows that arsenical ferrihydrite is by far the most widely-practiced and accepted method used worldwide. Finally, the disaster in Bangladesh is briefly discussed with reference to lessons that the metallurgical community might learn from this.

Jan 1, 2003

By Y. Takasaki

For zinc hydrometallurgical extraction, reducing the electric power consumption of the electrowinning process is an important issue for energy savings. At the Zinc & Lead 2000 symposium, the authors suggested that by using the Pb-0.5%Ag-0.6%Ca alloy, the electrolysis energy can be decreased compared to the conventional Pb-0.9%Ag alloy. In this study, the corrosion behaviors of the Pb-Ag-Ca electrode in a sulfuric-acid electrolyte were investigated. Based on the results Or me Pb-0.5%Ag-0.6%Ca anode after 20 days of electrolysis, the bath voltage and the quantity of anode slime decreased compared to the Pb-I%Ag anode. Subsequently, beta-PbO2 on the electrode surface was detected by XRD and its peaks were sharper than the Pb-1 %Ag anode. Moreover, a dense beta-PbO2 layer on the 0.6%Ca a anode surface was observed. Therefore, it was suggested that the dense beta-PbO2 layer on the anode surface is one of the factors that leads to a lower bath voltage and decreasing quantity of anode slime.

Jan 1, 2003

By A. G. Jackson, Rand R. Biggers, John D. Busbee, Iman Maartense, David P. Lubbers, David C. Liptak

"This paper describes the application of Raman Spectroscopy for characterizing superconducting YBCO thin film parameters. Attenuation of the substrate Raman spectrum as a function of material deposited is established. Also a correlation between film quality and Raman spectrum is explored. The identification and discrimination of superconducting and non-superconducting phases of YBCO is presented. The critical temperature (Tc) of a film as a function of its oxygen content is also established using Raman peak ratios. These results provide significant implications toward the use of Raman Spectroscopy for in situ monitoring and control of the PLD process. Film quality can be controlled via optimization of film oxygen content and reduction of improper YBCO phases. Film thickness can be controlled by monitoring the response of the substrate material. Also the PLD process can be studied and modeled using this powerful observation tool.IntroductionSuperconductors are materials that possess unique characteristics when cooled to sufficiently low temperatures. Below a material's critical temperature (Tc) it exhibits zero resistance to current flow. One such material, yttrium barium copper oxide (YBCO) has a critical temperature of approximately 92° K. Due to its high critical temperature YBCO is being aggressively researched for many possible applications, because of high current carrying capability and strong pinning of flux lines.YBCO in the 123 form is a ceramic material that was discovered in February, 1987. Its unit cell structure is shown in Figure 1 [ 1,2]."

Jan 1, 1997

By C. Lupi

Electric arc furnace dust generated during the production of steels is regarded as hazardous waste because of the presence of leachable elements such as Cr, Pb, Cd .... Different processes are available according to the management policy chosen by the steelmaker: disposal. recycle and/or recovery. The feasibility of an hydrometallurgical Zn recovery process on fumes generated during the pyrometallurgical treatment of EAF dust has been investigated. The recovery of metallic iron, chromium and nickel as molten metal provides fumes very rich in zinc oxide ( 63.1% ) and poor in zinc ferrite. This secondary dust is still an hazardous waste and represents the raw material for the recovery of Zn and Pb. The waste material is first leached in 1.5 M sulphuric acid at 30°C to provide a Zn, Fe and Mn rich aqueous solution and a Pb and Ca sulphate rich sludge. The iron is eliminated by precipitation because is harmful to the following electrowinning process. The ftltered and purified leached solution is acidified in order to obtain good electrowinning conditions. A pure cathodic deposit of zinc is then produced in an electrolytic cell at laboratory scale.

Jan 1, 1996

By Richard B. Stein

Bechtel's BEMSIM computer program is a useful tool for solvent extraction-electrowinning plant design optimization. Its power (up to 90 stream components, 240 process streams, 180 process steps) has been applied to investigate floweheet configurations in order to perform basic engineering, sizing of plant equipment and to optimize performance of commercial-size copper plants. Flowsheet variations presented include series, parallel and series-parallel extraction stages, while heat balances simulate operations in summer and extreme winter conditions. The BEMSIM program has also been applied to nickel-cobalt, gold and manganese extraction.

Jan 1, 1993