铁矿含碳球团还原后性能的实验研究

通过恒温还原实验,研究C,O摩尔比（C/O）、还原温度、还原时间和煤粉粒度4个因素对铁矿含碳球团还原后金属化率、孔隙率和抗压强度等性能的影响,观察球团断面的显微结构,分析球团还原过程和强度形成机理。结果表明：随还原温度的升高和还原时间的延长,球团的孔隙率降低,铁连晶的致密度增加,抗压强度提高;在C/O为0.67,还原温度1 200℃,还原时间35 min,煤粉粒度45μm以下质量分数为98.4%的实验条件下,含碳球团还原后的金属化率88.15%,孔隙率22.05%,抗压强度2 870 N。     

Preparation of pre-reduced pellet using pyrite cinder containing nonferrous metals with high temperature chloridizingreduction roasting technology—Effect of CaCl_2 additive

The role of CaCl2 during the high temperature chloridizing-reduction roasting process was investigated, aiming at acquiring high strength blast furnace burden with high iron grade and low nonferrous metals content. The effects of CaCl2 dosage on pelletizing, preheating and reduction were investigated. The results show that CaCl2 can improve the wet drop strength but reduces the thermostability of pyrite cinder green balls. When the dosage of CaCl2 exceeds 1%, the compressive strength of preheated pellets decreases while the growth of iron oxide particles is improved. Furthermore, the compressive strength of pre-reduced pellets increases but the metallization degree of pre-reduced pellets decreases with CaCl2 additive. The removal tests indicate that Zn can be removed completely without CaCl2 additive, Cu is removed only under the condition with CaCl2 additive and part of Pb must be removed by CaCl2 additive.     

硫酸渣成球性能研究

对硫酸渣成球性能进行了研究.对硫酸渣磨矿后,其粒度和成球性能得到很大的改善.通过对硫酸渣球团的落下强度、抗压强度和生球爆裂温度等进行测定,得出在粒度水平（74μm/95.1%）及膨润土为1.0%条件下,硫酸渣的成球性能较好,能够满足冶金工艺的要求.     

Pore Size Distribution of High Performance Metakaolin Concrete

The Compressive strength, porosity and pore size distribution of high performance metakaolin (MK) concrete were investigated. Concretes containing 0,5%,10% and 20% metakaolin were prepared at a water/cementitious material ratio (W/C) of 0.30.In parallel, concrete mixtures with the replacement of cement by 20% fly ash or 5 and 10% silica fume were prepared for comparison.The specimens were cured in water at 27℃ for 3 to 90 days .The results show that at the early age of curing(3 days and 7 days),metakaolin re-placements increase the compressine strength ,but silica fume replacement slightly reduces the compressine strength.At the age of and after 28 days ,the compressive strength of the concrete with metakaolin and silica fume replace-ment increases.A strong reduction in the total porosity and average pore diameter were observed in the conctete with MK 20% and 10% in the first 7 days.     

Extracting gold from pyrite roster cinder by ultra-fine-grinding and resin-in-pulp

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Effects of heating temperature on interfacial microstructure and compressive strength of brazed CBN-AlN composite abrasive grits

CBN-AlN composite abrasive grits and AISI 1045 steel were brazed using Ag-Cu-Ti active filler alloy by heating up to the temperature of 890,900 and 920 ℃,respectively,and then held at the temperature for 8 min.Optical microscope,scanning electron microscope and X-ray diffraction equipment were utilized to study the effects of heating temperature on the microstructure of the joining interface.The compressive strength of the brazed composite grits was also measured.The experimental results show that the atoms of Ti,Al,B and N have preferentially penetrated towards the joining interface of composite grits and filler alloy.The compounds of Ti-nitride,Ti-borides and Ti3AlN were formed in the reaction layer.Degradation effect was not made on the compressive strength of the CBN-AlN composite grits when the brazing process was carried out in the temperature range of 890-920 ℃.     

微波辅助H2O2-CH3COOH—DMF

以H2O2-CH3COOH为氧化剂,N,N-二甲基甲酰胺为萃取剂,在微波作用下对柴油进行脱硫实验。结果表明,在复合溶剂用量为理论用量的12倍,剂油体积比为0．25：1,辐射压力为0．4MPa、恒压辐射时间为6min,辐射功率375W,萃取剂与油体积比为1：1,静置时间为10min条件下,油品的脱硫率达到88．2％。与其它氧化脱硫法相比,脱硫率提高26％～42％,氧化剂用量减少20％～50％。     

鞍钢使用大比例赤铁矿生产氧化球团的研究

针对鞍山矿业大孤山球团厂生产氧化球团用磁铁矿不足的问题,进行了大比例赤铁矿生产氧化球团的实验室研究和半工业化链蓖机—回转窑生产试验．实验室研究结果表明,鞍千赤铁矿配比不超过40％时,球团矿抗压强度大于2500N／个,低温还原粉化指数RDI＋3.15大于82.05％,还原膨胀指数RSI小于15.02％,均能满足现代化大高炉生产的要求．工业试验表明,鞍千赤铁矿配比不超过40％时,生产稳定,产品质量全面满足鞍钢炼铁原料的技术要求．2011年进行了推广应用,生产实际结果表明,2011年比基准期增长创效4.2亿元．     

Utilization of thermally treated flue gas desulfurization (FGD) gypsum and class-C Fly Ash (CFA) to prepare CFA-based geopolymer

The feasibility of utilization of flue gas desulfurization (FGD) gypsum and Class-C fly ash (CFA) to prepare CFA-based geopolymer were studied. The results showed that geopolymer made from 90% CFA and 10% FGD gypsum (FGDG) which was thermally treated at 800 ℃ for 1 h obtained the better compressive strength of 37.0 MPa. The micro characteristics and structures of the geopolymer samples of CFA and CFA-FGDG were tested by XRD, FT-IR, and SEM-EDXA after these samples cured at 75 ℃ for 8 h followed by 23 ℃ for 28 d. Both the geopolymer samples of CFA and CFA-FGDG have significant asymmetric stretching of Al-O/Si-O bonds and Si-O-Si / Si-O-Al bending band. In geopolymer sample of CFA-FGDG, a small quantity of lathy products probably being the ettringite wrapped over the spherical fly ash particle, and the concentration of sulfur is much more than that in geopolymer sample of CFA. It is indicated that FGD gypsum may react during alkali-activated and geopolymeric process.     

Effect of activator and curing mode on fly ash-based geopolymers

The influences of concentration and modulus of sodium silicate solution and curing mode on the phase composition, microstructure and strength development in the geopolymers prepared using Class F fly ash were investigated. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and MAS NMR were utilized. Results show that the compressive strength increases as sodium silicate solution modulus increases, but when modulus exceeds 1.4, the compressive strength decreases, and it decreases markedly while the modulus is greater than 2.0. The compressive strength was improved by the increase of sodium silicate solution concentration. When the concentration is 32%, the compressive strength reaches the maximum, then it reduces as concentration increasing. Elevated temperature can increase the strength of samples that synthesized from sodium silicate solution with 32% concentration and modulus 1.2. Compared to the strength of the sample cured at 50 °C, the strength of the samples cured at 65 °C and 80 °C are higher at 1 d and 3 d, but the same at 7 d. At high temperature, prolonged curing time will decrease the strength. Long precuring at room temperature before application of heat is beneficial for strength development, and there is about 50% increase in strength of the samples cured at 1 d precuring and 2 d elevated temperature as compared to the strengths of the samples cured for 3 d at elevated temperatures or cured for 28 d at room temperature. The main product of reaction in the geopolymeric material is amorphous alkali aluminosilicate gel.     

Preparation of eco-environmental protection bricks from lake sludge

Eco-environmental protection hollow bricks manufactured from lake sludge collected from North Lake in Wuhan of China were investigated. At first, the recipes of round sam- pies（diameter in 5 cm and thickness in 1 cm） prepared by pressing molding under a pressure of 8 MPa and firing system were optimized, and properties such as bending strength, compressive strength, total shrinkage rate, water adsorption rate, apparent porosity and bulk density of the fired samples were tested. The experimental results showed that water adsorption rate and apparent porosity decreased, while bulk density increased with firing temperature increasing. Addition of additive can result in the improvement of strength of fired samples. At the same time, fly ash and additive may also broaden the firing temperature range and reduce firing temperature. Toxic characteristic leaching procedure （TLCP） tests of samples also show that the metal leaching level is low. The conditions for manufacturing good quality sample include 80% sludge with 10% additive and 10% flyash fired at 1000 ℃ for 60 min. Bending strength and compressive strength of samples prepared under the conditions are 24.64 MPa, 131.95 MPa, respectively,which are far beyond the requirements of clay solid bricks of CNS. Finally, according to the optimized recipe,the eco-environmental protection hollow bricks with the sizes of 40 mm × 38 mm ×25 mm were made and tested by extrusion molding. Compared with the Chinese National Standards （CNS： GB 13545-2003）, compressive strength, water adsorption and bulk denstiy of the hollow bricks are 11.55 MPa ,14.5% and 986 kg/m^3 when they were fired at 1040 ℃, which are far beyond the require of of CNS. Especially, its water adsorption arrives to standard of high-class products（16.0%） and compressive strength is above the hightest class（MU 10.0）.     

Roasting and chlorine leaching of gold-bearing refractory concentrate: Experimental and process analysis

This paper deals with gold extraction from a refractory concentrate by chlorine leaching. The process considers a pre-treatment of refractory materials by low temperature oxidation carried out with low oxygen concentration. The oxidized material is treated by leaching with brine. After gold adsorption/reduction onto activated carbon, iron and base metals can be precipitated by NaOH. Roasting tests show the necessity to carry out a thermal pre-treatment at least at 550 °C to obtain a reduction of sulfur and mercury in the material (50% and 90%, respectively). Highest gold extraction yield (around 93%) is obtained in the leaching test performed with material sample treated at 650 °C. This result confirms the necessity to optimize the thermal pre-treatment to improve Au recovery and to reduce chlorine consumption. A comparison with conventional cyanidation confirms that chlorination could be an useful alternative: in fact, gold extraction yield is quite low: 57% in non-pre-treated material and 25% in pre-treatment material.     

Effect of carbon fibre on properties of TiB2/C composite cathode coating for aluminum electrolysis

The tensile strength, compressive strength and electrical resistivity of TiB₂/C composite cathode coating were measured with a hydraulic pressure universal test machine and an electrical resistivity test device, and the effects of carbon fibre content and carbon fibre length on tensile strength, compressive strength and electrical resistivity were investigated. The results show that the tensile strength of coating increases at the beginning and then reduces with the increase of carbon fibre content when the carbon fibre (length of 3 mm) content ranges from 0 to 4.0%; at the carbon fibre content of 1.5%, the tensile strength of coating reaches the maximum, 25.6 MPa. For the coating with carbon fibre content of 1.5%, the carbon fibre length has a great influence on tensile strength and compressive strength of coating; when the carbon fibre length is 6 mm, the tensile strength and compressive strength of coating reach the maximum, 27.6 MPa and 39.2 MPa, respectively. The electrical resistivity of coating reduces with the rise of temperature and the length of carbon fibre, and the influence of carbon fibre length on electrical resistivity of coating at low temperature (30–200 °C) is more obvious than that at high temperature (960 °C). Foundation item: Project(2005CB623703) supported by the Major State Basic Research Development Program of China     

程潮铁精矿球团质量影响因素分析

以程潮铁精矿为原料进行造球试验,考察铁精矿粒度、膨润土种类及配比、造球水分和造球时间对球团质量的影响。结果表明,这几种因素对生球的落下强度、抗压强度和爆裂温度均有很大的影响;当程潮铁精矿中-0．074 m m粒级含量为85．10％、膨润土A配比为1．5％、造球水分为8％、造球时间为12 m in时,能得到生球落下强度为9．8次/（0．5m）、抗压强度为20．5N/个、生球爆裂温度为467℃的优质球团矿。     

Isothermal kinetics of the first stage reduction of magnetite cold bond pellets with carbon monoxide

The reduction of Fe₃O₄ to Fe is accomplished in two stages. In order to understand the reduction mechanism of magnetite cold bond pellets during the first period of heating-up process, it is necessary to study the kinetics of the reaction. In this work, the first stage of reduction of magnetite cold bond pellets, that is the reduction from Fe₃O₄ to FeO, has been investigated using an isothermal thermogravimetric method. Isothermal experiments were carried out at 750°C, 800°C, 850°C and 900°C, respectively. The results showed that the reaction was controlled by chemical reaction below 800°C, whereas, at higher temperature, it was controlled by a mixed controlled mechanism of chemical reaction and Ginstling-Brounshtein diffusion as well. Project supported by the Nonferrous Metals Industrial Corporation of China Synopsis of the author Chen Qiyuan, professor, born in 1948. Major research fields: metallurgical thermodynamics and kinetics.     

Influence of elevated curing temperature on the properties of cement paste and concrete at the same hydration degree

Three different curing temperatures(20 ℃, 40 ℃, and 60 ℃) were set, so that the nonevaporable water(w_n) contents of plain cement pastes cured at these three temperatures were measured to determine the hydration degree of cement. Tests were carried out to compare the pore structure and strength of cement paste, as well as the strength and permeability of concrete under different temperature curing conditions when their cements were cured to the same hydration degree. The experimental results show that either at a relatively low hydration degree(w_n=15%) or high hydration degree(w_n=16.5%), elevated curing temperature has little influence on the hydration products of cement paste, while it has a negative influence on the pore structure and compressive strength of cement paste. However, this negative effect is weaker at high hydration degree. The large capillary pore(100 nm) volumes of cement pastes remain almost the same at high hydration degree, regardless of curing temperatures. As for the concrete, elevated curing temperature also has negative influence on its compressive strength development, at both low hydration degree and high hydration degree. And this negative effect is stronger than that on cement paste's compressive strength at the same hydration degree. On the whole, elevated curing temperature has little influence on the resistance of concrete to chloride ion penetration.     

高硫煤电化学调浆浮选脱硫XRD谱研究

对山东兖州,内蒙乌达高硫煤进行了电化学调浆处理,运用X－射线衍射（XRD）测试技术从定性,定量两个方面对高硫煤电化学调浆浮选脱硫进行了研究,实证了煤中黄铁矿被氧化作为多硫化铁的事实。结果表明,电化学调浆不破坏煤的结构,经过电化学调浆浮选,能有效的脱除煤中硫,尤其是黄铁矿硫,它是一种温和,无污染,高效的脱硫新方法。     

超声作用下有机酸体系柴油深度氧化脱硫

在超声波的作用下,用H2O2-CH3COOH-FeSO4体系将柴油中的含硫有机物(主要为苯并噻吩类)氧化成相应的砜,用N,N-二甲基甲酰胺(DMF)作萃取剂将砜从柴油中萃取除去。考察了剂油体积比、氧化剂的质量分数、反应时间、超声声强等因素对柴油脱硫的影响。实验结果表明,在H2O2和油的体积比为0.024,CH3COOH和H2O2的体积比为0.5,FeSO4和H2O2的质量比为0.2,声强为0.3 W/cm2,反应时间为10 min的条件下,可使柴油脱硫率达到88.3%,收率可达92%以上。     

Square concrete columns strengthened with carbon fiber reinforced plastics sheets at low temperatures

Twenty-one square concrete columns were constructed and tested. The testing results indicate that bonded carbon fiber reinforced plastics (CFRP) sheets can be used to increase the strength and improve the serviceability of damaged concrete columns at low temperatures. The failure of the specimens, in most cases, takes place within the middle half of the columns. And the failure of strengthened columns is sudden and explosive. The CFRP sheets increase both the axial load capacity and the ultimate concrete compressive strain of the columns. The ultimate loads of strengthened columns at −10, 0 and 10 °C increase averagely by 9.09%, 6.63% and 17.83%, respectively, as compared with those of the control specimens. The axial compressive strength of strengthened columns is related to the curing temperatures. The improvement of axial compressive strength decreases with reducing temperature, and when the temperature drops to a certain value, the improvement increases with falling temperature.     

页岩烧结保温砌块砌体基本力学性能试验研究

通过对页岩烧结保温砌块砌体轴心抗压、沿通缝抗剪、剪压复合抗剪性能试验研究,分析其破坏特征和破坏机理。试验结果表明:页岩烧结保温砌块砌体受压破坏时,在竖向灰缝附近形成主裂缝,接近极限荷载时砌体出现表皮剥落现象;沿通缝抗剪破坏模式主要为单剪破坏,脆性明显;剪压破坏有剪磨、剪压和斜压3种类型;实测轴心抗压强度平均值高于规范值,沿通缝抗剪强度、复合抗剪强度平均值低于计算值,并分别给出砌体轴心抗压强度平均值、抗剪、剪压复合受力抗剪强度平均值建议公式;剪压复合抗剪强度随着压应力的增大而增大;建立了页岩烧结保温砌块砌体受压应力应变关系表达式;给出该类砌块的弹性模量和泊松比的建议值。