Search Documents

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 Maija-Leena Metsärinta

The behaviour of copper and lead in zinc roasting has been studied in laboratory scale roasting experiments as well as in large scale trials in an industrial fluidized bed, with the background of Outokumpu Kokkola Zinc smelter. Commercial zinc concentrates with a low and high ( up to 3 wt % ) copper content and with a low and high (up to 3.5 wt % ) lead content were oxidized to various desulphurisation degrees in the fluidized bed to establish the reaction mechanisms and the paths for copper and lead oxidation in the roasting. Influences of the agglomerate size on the roasting kinetics and micro-scale phenomena were also determined. Optical microscopy was used on the calcine and the findings are presented as numerous photographs of the polished cross sections. SEMIEDS techniques were used for analyzing chemically the phases and particle morphologies present in the samples. Computational thermodynamics was applied to the complex phase equilibria occurring during roasting in the agglomerating calcine. A complete oxidation of zinc concentrate with a high copper and lead content requires a careful control of oxygen coefficient in the roasting in order to maintain a stable operation of the fluidized bed. Oxygen coefficient thus seems to have a significant impact on the hydrodynamic stability of the fluidized bed with fine raw materials.

Jan 1, 2003

By Maija-Leena Metsiirinta

The behaviour of copper and lead in zinc roasting has been studied in laboratory scale roasting experiments as well as in large scale trials in an industrial fluidized bed, with the background of Outokumpu Kokkola Zinc smelter. Commercial zinc concentrates with a low and high ( up to 3 wt % ) copper content and with a low and high ( up to 3.5 wt % ) lead content were oxidized to various desulphurisation degrees in the fluidized bed to establish the reaction mechanisms and the paths for copper and lead oxidation in the roasting. Influences of the agglomerate size on the roasting kinetics and micro- scale phenomena were also determined. Optical microscopy was used on the calcine and the findings are presented as numerous photographs of the polished cross sections. SEM/EDS techniques were used for analyzing chemically the phases and particle morphologies present in the samples. Computational thermodynamics was applied to the complex phase equilibria occurring during roasting in the agglomerating calcine. A complete oxidation of zinc concentrate with a high copper and lead content requires a careful control of oxygen coefficient in the roasting in order to maintain a stable operation of the fluidized bed. Oxygen coefficient thus seems to have a significant impact on the hydrodynamic stability of the fluidized bed with fine raw materials.

Jan 1, 2003

By P. Henry

A novel electrochemical cell has been developed for the recovery of MnO2 from residue of pyrolusite ore leading loaded with Fe, Al Ni, Co and Si impurities, This new process can be considered as an alternative to the traditional methods : S02, H2O2 or bioleaching. It has been observed to proceed fairly rapidly and could prove to be a more economically viable process, as well as being more environmentally acceptable. Electrochemical characterization and kinetic studies have shown that MnO2 is effectively leached by electrogenerated ferrous ions at high current density from a pulp containing less than 5 g8 Fe. The chemical reactions are : Cathode (inox) : 2F23+ + 2e ? 2 Fe2+ Bulk: MnO2 + 2 fe2+ 4H+ ? Mn2+ + 2 Fe3+ + 2 H2O Anode (Pb-Ag) : H2O ? ½ O2 + 2H+ + 2e Global: MnO2 +2H+ Fe2+ = Mn2+ + H2O + 1/2 O2 The catholyte (MnO2 pulp) circulates upward in the expanded mesh cathode separated from the sulfuric acid solution anolyte by a separator which shows high mechanical resistance, low porosity, low potential drop, and reasonable cost. Laboratory and mini-pilot tests have led to the construction of an OT crating pilot plant (100 kg/hr) able to leach more than 95% of Mn, Ni, Co at 1000-1200 A/m2, 50°C with high faradic yield (> 95 %) and low power consumption (3.2 kWh/kg kWh/kg &4D). New applications like the treatment of spent Zn-Mn batteries, polluted soils, spent catalysts and oxide ore (cobalt, nickel) with electrogenerated redox species are now investigated at a laboratory and mini-pilot scale.

Jan 1, 2000

By Wen Liangying, Zou Chong, Tan Xiuqin, Bai Chenguang, Zhang Shengfu

"Eight typical metallurgical byproducts containing iron were selected based on the effect of the chemical composition, particle size, additives on the burnout degree of pulverized coal. Effect of three typical byproducts including fine iron ore, BOF dust and BOF sludge on combustion reactivity and combustion efficiency were investigated using TG-DSC method. The results indicated that the three additives have obvious catalytic effects on pulverized coal. By comparison, the relative active sequence of byproducts to the catalytic combustion can be described as follows: BOF dust>BOF sludge>fine iron ore. Moreover, adding BOF dust as component of additives also shows significant catalytic effects on combustion efficiency during rapid heating process.IntroductionChina is the largest producer in the world with an annual output reaching over 6 billion tons. Solid wastes arising from iron and steel making increases the environment pressure in recently years. For instance, annual output of dust during the production of iron and steel making in China reach up to 5 million tons, which is close to 8%~15% of the amount of steel [1]. Another characteristic of these byproducts is they are finer particle which are just harder to deal with. Since some of solid wastes, including dusts, scales, and sludge, usually contain high iron content, sintering plants have traditionally been used to recycle byproducts in integrated steel plants in China. However these byproducts also have noticeable effects on sinter quality, sinter strength and productivity and, therefore, waste recycling is limited depending on the analysis of the waste materials [2]. Another method which is pre-treatment of byproducts in pelletizing process, increases of energy consumption and production cost. In addition, metallurgical byproducts often contain heavy metals and alkalis. For these reasons, recycling rate of the byproducts in China is very low. Therefore, how to recycle the byproducts in iron and steel making process is an important subject."

Jan 1, 2012

By Jinliang Zhang, Jian Pan, Deqing Zhu

"Limestone and burnt magnesite were added to vary MgO content and basicity (CaO/SiO2 ratio) of pellets for investigating their influences on the properties of specularite pellets. At fixed MgO content, the addition of limestone does not affect on the properties of green balls significantly. The addition of burnt magnesite has obvious influence on the quality of green balls, especially on the thermal shock temperature. Without burnt magnesite, the thermal shock temperatures are about 400°C, and, the thermal shock temperature increases to 600~630°C by adding burnt magnesite. For preheated pellets, when the burnt magnesite is added, the compressive strength will be decreased. For roasted pellets without burnt magnesite, the calcium additives can form binding phase of calcium-ferrite, and suitable liquid phase will improve recrystallization of hematite, but excessive liquid will destroy the structure of pellets, so the compressive strength of pellet increases firstly and then decreases. When adding burnt magnesite, the compressive strength will increase as the basicity increases. When the basicity is more than 0.2, the compressive strength of the pellets various MgO content and basicity is above 2500N/pellet and then MgO-bearing fluxes can be added to prepare pellets with good high temperature properties.IntroductionWith the rapid development of the steel industry in China, oxidized pellets, possessing good mechanical and metallurgical properties, are becoming indispensable burdens for blast furnace ironmaking [1-3]. However, this has resulted in the shortage of domestic iron concentrates, so many Chinese steel plants begin to use imported hematite concentrate to prepare pellets. Compared with magnetite pellets, the hematite pellets require high roasting temperature and narrow roasting temperature range (1300–1350°C) and possess low compressive strength [4,5].1"

Jan 1, 2012

By Zhang Yongzhu

Developments on bioleaching of low grade ores and refractory gold ores by T. Ferrooxidans in China are summarized. Effect of the ions on bacterial growth, bioelectrochemical reaction mechanism of sulfide minerals and bacterial reaction mechanism are also discussed.

Jan 1, 1992

By E. F. Vegman, Ndabezinhle Dube

"In the practice of conventional sintering, production is always afflicted with the problem of being unable to get a uniform quality of produced sinter in the bed. Invariably the top layer of the sinter cake is composed of weak but highly sinter, while the bottom layer is over-fused, forming a sinter that is very strong but less reducible. These symptoms point to a variable distribution of the heat balance in the process of sintering which results in a deficit of heat in the top layers of the sinter bed and an excess of heat in the bottom layers, due to an increasing input of regenerated heat in the heat balance down the bed. This causes losses in the productivities of the sinter machine and the blast furnace.The current work was designed to improve on the solution to the above problem through the establishment of a more accurate combustion zone heat balance of the sintering process. This development is mostly on the method of determining the regenerated heat input in the overall heat balance. Previous methods were based on the assumption that the width and the velocity of the combustion zone remain constant through out its whole life, which is not the case since tests have shown that both its width and velocity increase as the combustion zone moves down the bed. In this work, these factors have been taken into account. Tests and calculations using the model were carried out for haematite and limonitic ores. The high sensitivity of the model to changes in the sinter mix composition and sintering conditions was demonstrated.The results present the following prospects:• The minimum theoretically possible coke breeze consumption during the sintering of any type of iron ore fines, under any sintering conditions, can be established.• The model can be used to control the metallurgical quality of the sinter in any point in the sinter bed since calculation data includes desired basicity, combustion zone temperature and FeO content in the sinter produced."

Jan 1, 2001

By J. A. Sekhar

Solidification processing/casting is increasingly being adopted as the preferred manufacturing technique for the fabrication of net shaped complex geometry components. Modeling of solidification processes is important both for design purposes as well as for understanding the physics of morphological evolution of the solidification microstructure. A fundamental aspect of such modeling involves the precise understanding? of heat transfer through the two phase solid/liquid region. A scheme to do this will be presented where the nonlinearity of the fraction liquid with change in temperature can be incorporated into the numerical calculations. The importance of properly accounting for the non-linear mushy zone will be discussed. Typical processes like squeeze casting and electromagnetic stirring will be discussed to illustrate how precise modeling of the solid/liquid region can aid in the calculation of accurate heat transfer coefficients for these processes.

Jan 1, 1990

By Y. K. Rao

In the carbonyl process for the refining of crude nickel CO(g) reacts with nickel in the 310-370K range producing nickel tetracarbonyl, Ni(C0)4(g). Iron and cobalt impurities also form gaseous carbonyls but their partial pressures are low. The carbonyl is led to a decomposer plant wherein the gas disproportionates in the 500-600K range depositing pure metal on nickel pellets that move countercurrent to the gas-flow. This system serves to illustrate the fundamental principles involved in the vapor phase mass transport of elements, against temperature-gradient, under the influence of chemical potential gradient. Unlike in the crystal growth, the source is at a lower temperature (say 350K) whereas the seed is in the hot-zone (say 550K) of the closed ampoule-type reactor. By assuming virtual gas-solid equilibria in the end zones, with diffusion of gaseous species between them acting as a slight perturbation, the quasi-steady- state mass-transport rates are computed for a range of CO-pressures and temperatures.

Jan 1, 1993

By Vianey Garcia-Osorio

One of the problems in the carbothermic aluminum process is the substantial loss of aluminum compounds as vapors due to the high temperatures in the process. In order to solve this problem a Vapor Recovery Unit (VRU) is proposed. In this unit operation the aluminum vapor undergoes a series of heterogeneous non-catalytic reactions forming solid, liquid and gas products. In this work a model for the simulation of this unit was developed which includes heat and material balances as well as heterogeneous non-catalytic reactions. The model leads to a system of differential equations; its solution was implemented in Matlab giving as a result a stage-by- stage solid-fluid reaction model.

Jan 1, 2001

By D. Donald Downey

Pilot Testing Ion Exchange Resin (IEX) can go from very simple beaker testing to complicated column testing. Space velocities, regenerant quantities, loading capacities, ion leakage, are all terms that get accumulated together to prove or disprove a resin’s (or resins’) ability to load a single ion (or specific set of ions). Not getting all the resin’s operating parameters correct will disqualify (or at least skew) the results. Laboratory tests for capacity, moisture content, bead size, metals fouling, etc.—what does it all mean? At last count, there were over twenty-five separate ion exchange resin tests (analyses) that were available to end users. Standard testing procedures identify the resin properties but more specific procedures can be used to identify problems with equipment operation. Then, there are the costs to consider; simple cation resin testing (moisture content, total capacity and bead integrity) is in the $200/sample range. However, add to this Chatillon, Russian Ball Mill Test, HIAC particle size, metals and % regeneration test procedures and the lab work can increase to over $1000/sample. In this paper, the author will explain the “must-do” pilot and test procedures and why they are important and the key to understanding how resin performs ion exchange.

By José Carlos Abreu

This work presents a kinetics study covering the effects of temperature over the reduction rates of a carbon composite briquette, aiming its use as burden in some of the new alternate ironmaking technologies, such as the Tecnored process. It is reported that increases in the temperature increases the reaction rate. Additionally, the morphology of the iron phase generated during the reduction of these briquettes is presented. It was possible to verify that three types of iron morphology occurred during the process: an external, dense and continuous iron layer, the presence of iron globules at the center of the briquettes and whiskers at the briquette's core. The measurement of the carbon content on the globules and the external iron layer is also presented.

Jan 1, 2003

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 Thomas E. Weyand

Prior to 1975, lead-based paints were commonly used in protecting steel structures. Because of the toxic effects of lead on human health and the environment, their use has been significantly reduced. However, problems with these paints persist when they are removed during normal maintenance by pneumatic blasting with mineral abrasives. Technologies are developed to contain the spent abrasive and paint during blasting operations. This paper reports on A study to identify beneficial reuses for the spent blasting material. Nine samples were gathered from different projects within Pennsylvania. The samples were thoroughly characterized with regard to composition, morphology, and EP and TCLP leach test performance. Potential reuse applications will be reviewed with regard to technical adequacy, economics, and environmental constraints.

Jan 1, 1992

By A. E. Isaacson

The U.S. Bureau of Mines is studying the effect of supercritical water, at 400' C and 3,500 psi, and subcritical water, at lower temperatures and pressures, on mixtures of minerals and metals to determine the possible applications of water at high temperature and pressure for processing these materials. This research was conducted using a flow-through bench-scale system. Copper-bearing minerals studied were chalcocite, chalcopyrite, covellite, and cuprite. In general, mixtures of copper minerals and pyrite reacted to form bornite. Intermediate phases formed were chalcopyrite and digenite. Similar reactions occurred between pyrite and metallic copper. A mixture of chalcopyrite and pyrite was inert in supercritical water'. The reaction between cuprite and metallic zinc yielded metallic copper. The cuprite was reduced by hydrogen generated by the reaction between metallic zinc and water. None of the reactions occurred exclusively in supercritical water, but also occurred in water at high temperature and pressure below the critical point. 'Experimental results did show that a dual-reaction process, consisting of solid-state diffusion and fluid transport, was occurring.

Jan 1, 1989

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 Xie Hao

According to its raw materials orthogonal test scheme is designed and a large number of systemic experiments were carried out in order to study the sintering characteristics of three types of fine ores in Kunming Iron&Steel Co.Ltd(KISC). The effects of carbon mixture ratio and basicity on sintering time, agglomeration ratio, physical properties and utilize coefficient were researched via single factor analysis and range analysis. The experimental results show the best mixture ratio of each fine ore. Analysis found that the influence of the carbon mixture ratio is more significant than which of the basicity on the sintering process except agglomeration ratio of foreign ore.

Jan 1, 2009

By Marco V. Ginatta

Current world production, 60'000 ton/y, is exceedingly too small for titanium's extraordinary combination of favorable properties; it should be 1,000,000 ton/y (7% of stainless-steel). Prices that competitively sustain that sales volume are achievable only with electrolytic production, as it is for all other commercial nonferrous metals. But titanium does not have its commercial electrolytic plants yet, because of producers decisions and strategies, scientists works, industrial problems with chloride process, lack of consumers sponsors. Fluoride high temperature process has the advantages of aluminum electrolysis, plus other favorable characteristics specific to titanium and its feed material. One electrolytic titanium potroom replaces several different plants used for sponge production. Production of titanium ingots with zero defect is achieved. The solidified cathode rectangular slabs are suitable for direct rolling.

Jan 1, 2001

By José Carlos Abreu

This work presents a kinetics study covering the effects of temperature over the reduction rates of a carbon composite briquette, aiming its use as burden in some of the new alternate ironmaking technologies, such as the Tecnored process. It is reported that increases in the temperature increases the reaction rate. Additionally, the morphology of the iron phase generated during the reduction of these briquettes is presented. It was possible to verify that three types of iron morphology occurred during the process: an external, dense and continuous iron layer, the presence of iron globules at the center of the briquettes and whiskers at the briquette's core. The measurement of the carbon content on the globules and the external iron layer is also presented

Jan 1, 2003