Black Dross: Processing Salt Removal from Black Dross by Thermal Treatment

The salt removal from black dross by thermal treatment has experimentally been studied under different conditions in both a stationary resistance furnace and in a laboratory scale rotary furnace. The experiments were designed based on partial pressure calculations using the Thermo-Calc software (Thermo-Calc Software, Stockholm, Sweden). The salt removal efficiency was evaluated by scanning electron microscope (SEM) energy-dispersive x-ray spectroscopy and x-ray diffraction analyses, and the optimum conditions for treatment established, i.e., temperature, gas flow rate, holding time, rotation rate, and sample size. The overall degree of chloride removal was established to increase as a function of time and temperature, as well as by reduced pressure. Under atmospheric pressure, the highest degree of chloride removal from a 20 g sample was obtained after 10 h at 1523 K resulting in a 98% removal and a final chloride content of 0.3 wt.% in the residue. Under reduced pressure, the chloride concentrate was lowered to 0.2 wt.% after thermal treatment of a 20 g sample at 1473 K for 8 h. In the case of 200 g samples treated in a rotary furnace, the chloride concentrate was 2.5 wt.% after 14 h at 1523 K, representing a removal of 87%. Below 0.3 wt.% chloride content, the material is deemed a nonhazardous waste.     

蓄热式燃烧技术在石特加热炉的应用与改进

介绍了石特棒材线双蓄热步进梁式加热炉的工艺条件、技术参数、蓄热式烧嘴和换向阀的特点,并针对该加热炉存在的蓄热能力不足、蓄热体寿命短、加热质量下降、换向阀故障率高而寿命短、煤气消耗上升等问题,通过增大蓄热体换热面积、将原有烧嘴的扁缝式喷口砖改为多孔射流板、将原旋瓣式三通阀改为直通双关式三通阀、改进加热炉燃烧自动控制系统,使加热能力由改造前的110t/h提高至150t/h,蓄热体寿命由8个月提高到15个月,换向阀的换向周期由60s延长到100s以上,使用寿命由1年延长到3年以上,且改善了加热质量,提高了加热炉的安全性。     

H2SO4分解富钛精矿的反应动力学

攀钢含钛高炉渣是一种尚待开发利用的钛资源,选用攀钢含钛高炉渣选择性分离后的富钛精矿为原料,以液－固异相反应的收缩未反应芯模型研究了硫酸法制取钛白的反应动力学过程,根据搅拌强度和温度对反应的影响判别反应为膜扩散控制过程,分析了反应速度的温度因素和粒度因素,导出了硫酸分离富钛精矿的动力学方程式,并按该方程计算得到反应温度在60－80℃的活化能力为34．59kJ/mol。     

Theoretical analysis and experimental verification of thermal decomposition mechanism of CuSe

Experiments on the thermal decomposition of CuSe were carried out by using a thermogravimetric analyzer (TGA) at different heating rates. The kinetic parameters and mechanisms were discussed based on model-free and model-based analyses. The decomposition rate and decomposition behavior of CuSe were investigated by using a vacuum thermogravimetric furnace. The results showed that the R3 model was identified as the most probable mechanism function under the present experimental conditions. The average values of activation energy and the pre-exponential factor were 12.344 J/mol and 0.152 s^-1, respectively. The actual decomposition rate of CuSe was found to be 0.0030 g/(cm²·min).     

蓄热式燃烧技术在大型低热值煤气环形加热炉改造中的应用

湖北新冶钢集团公司Φ170mm轧管机组中径21m的环形加热炉由于燃烧系统配置不合理．一直未能达到设计加热能力,仅为35t／h且能耗高,严重制约了机组生产能力的发挥。采用蓄热式燃烧技术对炉子燃烧系统进行改造后,该加热炉的加热能力明显提高,实测达到55t／h,最大达到60t／h;加热温度均匀,节能效果明显,管坯加热过程中无待温时间,满足了扩大生产能力的要求。     

Kinetic study on pressure leaching of high iron sphalerite concentrate

The kinetics of pressure leaching high iron sphalerite concentrate was studied.The effects of agitation rate,temperature, oxygen partial pressure,initial acid concentration,particle size,iron content in the concentrate and concentration of Fe2 added into the solution on the leaching rate of zinc were examined.The experiment results indicate that if the agitation rate is greater than 600 r/min,its influence on Zn leaching rate is not substantial.A suitable rise in temperature can facilitate the leaching reaction,and the temperature should be controlled at 140-150℃.The increase trend of Zn leaching rate becomes slow when pressure is greater than 1.2 MPa,so the pressure is controlled at 1.2-1.4 MPa.Under the conditions of this study,Zn leaching rate decreases with a rise in the initial sulfuric acid concentration;and Zn leaching rate increases with a rise of iron content in the concentrate and Fe 2 concentration in the solution.Moreover,the experiment demonstrates that the leaching process follows the surface chemical reaction control kinetic law of“shrinking of unreacted core”.The activation energy for pressure leaching high iron sphalerite concentrate is calculated,and a mathematical model for this pressure leaching is obtained.The model is promising to guide the practical operation of pressure leaching high iron sphalerite concentrate.     

锡精矿沸腾炉工艺参数与焙烧关系探讨

根据锡精矿的特点和沸腾炉的特性,阐述了锡精矿在沸腾炉焙烧中的应用,并对结构工艺参数与焙烧过程进行了探讨.     

Kinetics of the reactions in the smelting furnace of the Mitsubishi process

In this paper, the authors present the results of theoretical calculations on the rates at which copper concentrate particles and silica particles dissolve in the matte in the smelting furnace of Mitsubishiprocess. Those calculations indicate that the concentrate particles dissolve rapidly in matte, in less than 1 ms, whereas silica particles dissolve at a much slower rate, and they dissolve mainly in the bulk matte in the smelting furnace. Some advantages of bath smelting over flash smelting are given. For more information, contact Zenjiro Asaki, Mitsubishi Materials Corporation, Central Research Institute, 1-297 Kitabukuro-cho, Omiya, Saimtama, 330-8508, Japan.     

煤气反吹技术在蓄热式加热炉上的应用

本文从煤气反吹技术在蓄热式加热炉上的应用情况出发,阐述了轧钢加热炉蓄热式高温燃烧系统在生产中出现的问题,详细分析了普通蓄热式技术及其不足,介绍了煤气反吹技术的工作原理、特点、应用效果,山钢集团淄博张钢有限公司对其1座140t/h蓄热式高线加热炉进行的热平衡测试表明,炉子单位能耗为0. 907 GJ/t坯。     

Soviet design for roasting zinc concentrates in a fluidized bed

Although many zinc plants attempt to increase a fluidized bed roaster’s capacity by employing an oxygen-enriched air blast, work in the former Soviet Union shows the advantages of redesigning the roasting complex to optimize concentrate flow and process hydrodynamics. A redesigned furnace in operation for five years demonstrates, as compared to conventional Soviet furnaces, greater versatility, improved charge capacity, better heat recovery, ease of control, and operational stability.     

High-temperature oxidation of a nickel base superalloy at different oxygen partial pressures

A series of oxidation tests were conducted for a nickel base superalloy, as these materials are used at high temperature in aggressive conditions, thus the influence of oxygen on their degradation mechanisms must be known. The material was treated for up to 150?h at 900 and 1000°C in a furnace able to control and maintain atmospheres with different partial oxygen pressures. The oxidation rate of the material was determined by gravimetric means. In all cases, the rate of oxidation followed parabolic regimes that depended on the value of oxygen partial pressure. The oxide scale formed was characterised by X-ray diffraction and scanning electron microscopy; these analyses revealed that the oxide scale consisted of an outer TiO₂ layer and inner Cr₂O₃ layer under all experimental conditions. Cross-section analyses indicated the development of internal oxidation and the presence of gamma-prime free zones.     

Preparation and electrochemical properties of LiFePO4/C composite with network structure for lithium ion batteries

The bare LiFePO4 and LiFePO4/C composites with network structure were prepared by solid-state reaction. The crystalline structures, morphologies and specific surface areas of the materials were investigated by X-ray diffractometry（XRD）, scanning electron microscopy（SEM） and multi-point brunauer emmett and teller（BET） method. The results show that the LiFePO4/C composite with the best network structure is obtained by adding 10% phenolic resin carbon. Its electronic conductivity increases to 2.86 × 10^-2 S/cm. It possesses the highest specific surface area of 115.65 m^2/g, which exhibits the highest discharge specific capacity of 164.33 mA.h/g at C/IO rate and 149.12 mA.h/g at 1 C rate. The discharge capacity is completely recovered when C/10 rate is applied again.     

Untersuchung über die Auswirkung der Elementbildung zwischen Stahl in Beton und Stahl in Erdboden

Investigation of the effect of galvanic corrosion between steel in concrete and steel in soil The investigation of cathodic polarization of steel in concrete on samples of portland cement and blast furnace cement revealed that oxygen reduction on steel in portland cement is less hindered than on steel in blast furnace cement. As to the magnitude of the cathodic current the aeration of the samples is important. Dry stored samples before measuring case a higher current density than wet stored ones. A significant relationship of the cathodic current depending on the water/cement value and the storage time of concrete could not be ascertained. The polarization resistances for portland cement samples lie within 86 and 3000 kΩ · cm² and for blast furnace cement samples between 430 and 5100 kΩ · cm². The measurements of the anodic current densities on corrosion cells of steel in concrete/steel in solution and steel in wet sand respectively rendered, by varying the cathode/anode aspect ratio from 1000: 1 to 1: 1, values for portland cement samples between 560 and 1,2 μAJcm² (corresponding to an annual corrosion of 6,5 and 0,014 mm respectively), and for blast furnace cement samples values between 730 and 0,28 μA/cm² (corresponding to an annual corrosion rate of 8,5 and 0,003 mm respectively). A decrease of the anodic current density variable with time could not be observed during the 28 days of measurements. On account of the investigations the following conclusions can be made: A formation of a corrosion cell with steel in concrete/steel in soil is particularly then to be expected if the concrete is dry on one side, e.g. the foundation of a building where oxygen diffuses by way of the gas pores in the concrete from the inner side to the cathode. This is less serious if the concrete is fully embedded in soil and thoroughly moistened. In this case the transport of oxygen has to be carried via waterfilled pores.     

Unicase炉的烘炉与炉膛时效

介绍了Unicase炉烘炉与炉膛时效的工艺 ,阐述了烘炉的注意事项 ,分析了甲醇流量对炉膛时效的影响以及在采用不同的碳势控制装置进行炉膛时效时应注意的事项。     

Cyclic voltammetry and potentiodynamic polarization studies of chalcopyrite concentrate in glycine medium

Cyclic voltammetry and potentiodynamic polarization analyses were utilized to investigate the mechanism and kinetics of glycine leaching reactions for chalcopyrite. The effects of pH (9–12), temperature (30–90 °C) and glycine concentration (0–2 mol/L) on corrosion current density, corrosion potential and cyclic voltammograms were investigated using chalcopyrite concentrate–carbon paste electrodes. Results showed that an increase in the glycine concentration from 0 to 2 mol/L led to an increased oxidation peak current density. Under the same conditions, corrosion current density was found to change from approximately 28 to 89 μA/cm^bwhereas corrosion potential was decreased from –80 to –130 mV. Elevated temperatures enhanced the measured current densities up to 60 °C; however, above this level, current density was observed to decrease. A similar current density behavior was determined with pH. A pH change from 9 to 10.5 resulted in an increase in current density and pH higher than 10.5 gave rise to a reduced current density. In addition, the thermodynamic stability of copper and iron oxides was found to increase at higher temperatures.     

The Mechanical and Microstructural Changes of Sn-Ag-Bi Solders with Cooling Rate and Bi Content Variations

The purpose of this study is to investigate the influence of cooling rate and Bi addition on the microstructure evolution and mechanical properties of Sn-3.5Ag alloy. A series of Sn-3.5Ag-xBi solders has been fabricated with Bi content in the range of 0.5-3.5 wt.%. After solution heat treatment at 170 °C for 24 h and subsequent aging heat treatment at 100 °C for 2 h, samples were divided into two groups. One group was rapidly quenched into iced water (water quenching) for the fast cooling rate (20 °C/s), while the second group was slowly cooled (furnace cooling) in the furnace for the slow cooling rate (0.2 °C/s) after the furnace reflow. The microstructural evolutions of the present solders have been investigated using x-ray diffraction and scanning electron microscopy. The microhardness was measured to correlate the mechanical properties to alloy compositions and cooling rate. It was found that the microhardness of Sn-3.5Ag-xBi solders increased with increasing cooling rate. The indentation creep curves have been evaluated from the obtained microhardness values. Results revealed the steady-state creep rate decreased with increasing Bi content exhibiting an anomalous behavior at 2.5Bi. The reason for improved creep resistance of Sn-3.5Ag-xBi solders is the result of the combination of the solid solution strengthening and precipitation strengthening of Bi. The mean values of stress exponent indicated that the operative creep mechanism is dislocation climb.     

铸造厂感应电炉的选型

阐述中频电炉在铸造厂的应用，讨论感应电炉选型时需要考虑的因素，电炉容量和功率大小与工艺需求的关系，电源类型，电源与电炉的配置等与工艺需求的关系。对感应电炉选型时容易混淆的电炉熔化率与生产率的关系，展开讨论，引入功率利用系数的概念。     

Effect of Cooling Rate on Microstructure and Mechanical Properties of Eutectoid Steel Under Cyclic Heat Treatment

A systematic study has been carried out to ascertain the effect of cooling rate on structure and mechanical properties of eutectoid steel subjected to a novel incomplete austenitization-based cyclic heat treatment process up to 4 cycles. Each cycle consists of a short-duration holding (6 min) at 775 °C (above A₁) followed by cooling at different rates (furnace cooling, forced air cooling and ice-brine quenching). Microstructure and properties are found to be strongly dependent on cooling rate. In pearlitic transformation regime, lamellar disintegration completes in 61 h and 48 min for cyclic furnace cooling. This leads to a spheroidized structure possessing a lower hardness and strength than that obtained in as-received annealed condition. On contrary, lamellar disintegration does not occur for cyclic forced air cooling with high air flow rate (78 m³ h^?1). Rather, a novel microstructure consisting of submicroscopic cementite particles in a ‘interweaved pearlite’ matrix is developed after 4 cycles. This provides an enhancement in hardness (395 HV), yield strength (473 MPa) and UTS (830 MPa) along with retention of a reasonable ductility (%Elongation = 19) as compared to as-received annealed condition (hardness = 222 HV, YS = 358 MPa, UTS = 740 MPa, %Elongation = 21).     

酒钢2号高炉强化冶炼生产实践

酒钢2号高炉原地大修扩容改造以后,不断尝试高炉强化冶炼途径。通过采取高风温、大富氧、高喷煤比、低硅冶炼以及提高风压控制水平和炉顶压力等多种强化冶炼手段,取得了十分明显的高炉强化冶炼效果,利用系数不断提高,高炉各项技术经济指标得到不同程度改善。     

Thermodynamic Analysis of Looping Sulfide Oxidation Production of MoO2 from Molybdenite for Energy Capture and Generation

Conventional processing of molybdenum sulfide concentrates involves decades-old technology and often inefficient processing. Molybdenum trioxide (MoO₃) is produced from the sulfide concentrate and used by the steel industry to produce steel alloys. An alternative and more attractive molybdenum product, molybdenum dioxide (MoO₂), is produced using the Looping Sulfide Oxidation process. By examining the thermodynamics of the molybdenum-sulfur-oxygen system, the conditions necessary to selectively produce MoO₂ over the trioxide have been identified. Under such conditions, oxygen, MoO₃, or a mixture of the two can be used to convert the sulfide concentrate. Some of the resulting MoO₂ is collected as final product, while some is oxidized to MoO₃ and looped back to the conversion furnace to complete the cycle. A thermodynamic analysis of the reaction schemes and a discussion of the potential for energy capture are presented. The Looping Sulfide Oxidation process presents a paradigm shift in the production and consumption of molybdenum.