几种新型可锻铸铁的研究

本文综述了作者近两年来研制的几种新型可锻铸铁的化学成分、热处理工艺、组织和性能方面的特点,为扩大可锻铸铁的应用范围提供了理论依据。有的已经转让给工厂用于曲轴、钢帽等零件的试制。     

对云南雪山铁矿开发地质灾害危险性评估

根据实地调查和已有资料,对云南省禄劝县雪山铁矿开发进行了地质灾害危险性评估,并提出了地质环境、地质灾害防治措施。     

助溶酸浸硫铁矿烧渣的研究

采用常压下助溶酸浸的方法对提取硫铁矿烧渣中的铁进行了研究,得到硫铁矿烧渣中铁浸出率的影响因素及规律。结果表明,影响铁浸出率的主要因素为硫酸浓度、反应时间和温度、硫酸用量系数、助溶剂用量及热水用量;当硫酸用量系数为1.05、硫酸浓度为65%-70%、反应温度为125℃、反应时间为3-4 h、助溶剂用量为烧渣量的16%-20%、热水用量为烧渣量的1倍或1.8倍时,铁的浸出率可达95%以上。     

Bio-oxidation of pyrite, chalcopyrite and pyrrhotite by Acidithiobacillus ferrooxidans

This paper deals with the bio-oxidation processes by Acidithiobacillus ferrooxidans of pyrite, chalcopyrite and pyrrhotite. Our experimental results show distinctive bio-oxidation characteristics for the three sulfide minerals. In the presence of A. ferrooxidans, the sulfide oxidation rates generally decrease in the order of pyrrhotite, chalcopyrite and pyrite. The pH during bio-oxidation of pyrite tends to decrease as a whole, whereas a rise-fall pattern was recorded for both chalcopyrite and pyrrhotite in their pH variations. No deposition was observed during the bio-oxidation of pyrite, suggesting a possible link to lower pH value in the process. However, large amounts of jarosite and element sulfur were determined in the bio-oxidation processes of chalcopyrite and pyrrhotite. A. ferrooxidans individuals were found directly as attachments to erosion pits on the smooth surface of pyrite. The erosion pits are similar to the bacterium in shape and length, and thus are probably products of dissolution of organic acid secreted by the cells on the mineral surface. More complicatedly, biofilm exists on the surfaces of chalcopyrite and pyrrhotite. This type of structured community of A. ferrooxidans is enclosed in the extracellular polymeric substances (EPS), and covered with the deposition generated in the bio-oxidation processes of chalcopyrite and pyrrhotite. Different bio-oxidation processes of pyrite, chalcopyrite and pyrrhotite may be linked mainly to characteristics of individual minerals and the pH in the reaction solution of the bio-oxidation system.     

铊的环境生态迁移与扩散

报道某含铊黄铁矿矿石和各工艺过程产物中铊的含量和分布 ,各类矿石中铊含量范围 10 .0～ 5 6 .4× 10 -6;尾砂矿中铊含量约 5 0× 10 -6;炉渣中铊含量范围 2 1.7～ 4 5 .4× 10 -6;炉灰中铊含量 30 .2～ 6 8.1× 10 -6;矿区山泉水中铊含量 0 .35～ 7.86× 10 -9;选矿水中铊含量 4 .82× 10 -9;自来水中铊含量 10～ 30× 10 -12 ;硫酸厂解析水中铊含量5 5 .2～ 4 5 0× 10 -9;炉尘冲洗水中铊含量 17.1～ 37.9× 10 -9;炉渣冲洗水中铊含量 4 .2 2× 10 -9;排放水中铊含量 9.30～ 2 1.6× 10 -9.根据这些数据 ,讨论了铊在自然环境中的迁移、转化、扩散过程和生态污染 ,提出了在含铊矿产资源利用过程中 ,必须高度重视铊的环境污染效应和后果 ,采取必要的预防污染措施 ,同时应积极开展治理技术研究 .     

Fe/ 硼酸盐缓冲溶液界面性质的交流阻抗研究

结合线性电位扫描、开路计时电位和交流阻抗技术研究了Fe在硼酸盐缓冲溶液(pH=8．4)中不同电位区间的界面性质．在氮气气氛下，电位低于-0．77V，界面发生析氢反应，反应受电子转移步骤控制。同时存在氢原子的表面吸附过程；-0．77V至0．60V间，Fe氧化成2价Fe而发生活性溶解，同时2价Fe进一步氧化成3价Fe，二步反应均受电子转移步骤控制；至0．60V，形成具有保护作用的单层Fe304；-0．60V至-0．50V间，Fe氧化成2价Fe的反应随电位升高而变慢，表现为负的反应电阻；-0．50V至0．90V间，Fe进入钝化区，较低电位下主要是Fe304转化成Fe2O3的过程，受电子转移步骤和0H^-在钝化膜中的扩散步骤混合控制，较高电位下Fe直接氧化成3价Fe。受电子转移步骤和3价Fe离子在钝化膜中的扩散步骤混合控制；电位高于0．90V，界面发生析氧反应和氧化膜溶解，反应受电子转移步骤控制，反应过程中有中间产物吸附．     

零价铁修复沉积物中菲的正交实验研究

多环芳烃(PAHs)是一种致癌、致畸、致突变且难生物降解的持久性有机污染物。选择PAHs典型代表——菲作为研究对象,利用零价铁还原修复表层沉积物中的菲,并通过正交实验研究不同条件下温度、零价铁的粒径与添加量对修复效果的影响。实验结果表明:当温度为25℃、零价铁的粒径为0.15 mm、零价铁的添加量为2 g的条件下,修复效果最好,去除效率可达77.43%。     

钒钛抗磨铸铁衬板的工艺改进

钒钛抗磨铸铁衬板的夹砂、断裂缺陷是影响质量的关键因素.现通过有针对性的改进现场生产工艺.调整其化学成份,在满足用户质量要求的前提下,降低了废品率。     

无相同类型标准样品下材质的光电光谱法测定

介绍无相同类型标准样品下铁基线材、高铬铸铁及高锰钢的光电光谱定量测定方法。该方法是通过选用分析材质同基体的任一套标准样品绘制校准曲线,采用自编的计算机校正程序,找出试样的光谱分析值和化学分析值之间的关系模型,并将模型拟合到指定的控制样品中,当进行材质测定时,只需在日常标准化操作后将拟合好的控制样品对校准曲线进行控样校正,就可以直接进行无相同类型标准试样的定量分析。该测定方法简单、实用,测定结果基本与化学分析值一致。     

Cellular regulation and molecular interactions of the ferritins

Controlling iron/oxygen chemistry in biology depends on multiple genes, regulatory messenger RNA (mRNA) structures, signaling pathways and protein catalysts. Ferritin, a protein nanocage around an iron/oxy mineral, centralizes the control. Complementary DNA (antioxidant responsive element/Maf recognition element) and mRNA (iron responsive element) responses regulate ferritin synthesis rates. Multiple iron-protein interactions control iron and oxygen substrate movement through the protein cage, from dynamic gated pores to catalytic sites related to di-iron oxygenase cofactor sites. Maxi-ferritins concentrate iron for the bio-synthesis of iron/heme proteins, trapping oxygen; bacterial mini-ferritins, DNA protection during starvation proteins, reverse the substrate roles, destroying oxidants, trapping iron and protecting DNA. Ferritin is nature’s unique and conserved approach to controlled, safe use of iron and oxygen, with protein synthesis in animals adjusted by dual, genetic DNA and mRNA sequences that selectively respond to iron or oxidant signals and link ferritin to proteins of iron, oxygen and antioxidant metabolism. Received 25 June 2005; received after revision 17 October 2005; accepted 25 November 2005