铅锌冶炼过程产生废气节点危害性分析

采用重金属的潜在生态危害和毒理学毒性系数对某铅锌冶炼厂产生废气节点的危害性综合指数进行分析,确定主要废气节点的危害性顺序,为各个产生废气节点分级管理控制提供依据。结果表明,产生废气节点潜在生态危害性综合指数和毒理学危害性综合指数的最大值分别为0.253 9和0.300 1,最小值均为0.001 8。危害性最高的节点为熔铅布袋,该节点为关键污染物控制节点,在生产过程中需要重点管理。     

铅金分离的工艺探索

探索了铅金分离的3种工艺流程,即"混合浮选"、"先硫后氧"、"先铅后金"流程。通过试验探索表明,"先铅后金"工艺优于其他两种工艺。其闭路试验获得较好指标,铅精矿中铅品位达51.11%,金精矿中金品位23.32 g/t;铅、金的总回收率分别为83.82%和81.03%;同时,银也得到了有效回收。     

铅冶炼中有价金属的回收利用

铅矿石中伴生的有价金属元素是非常珍贵的自然资源,在铅冶炼过程中对其进行回收利用既提高了资源利用率,又为企业带来了利润。文章以氧气底吹熔炼-电热熔融还原炼铅法为例,介绍了铅冶炼过程中锌、铜、金、银、铋、锑元素的回收工艺。     

火法炼锑除铅渣中锑铅回收工艺研究

将火法炼锑中产生的除铅渣,与铁屑、碱按一定比例混合均匀,升温到1 050~1 350℃,并保温30~90 min,让混合物熔融、反应、澄清、冷却,得到锑铅合金和浮渣。通过该方法,除铅渣中的锑、铅分别有95%、92%以上进入锑铅合金中,浮渣中的锑、铅含量在1%以下,锑、铅得到充分回收,处理流程简短,整个过程不产生三废。该工艺与现有的其它处理方法相比有更多的优点。     

宏程序加工圆弧螺纹的编程研究

以变半径圆弧形螺纹数控车削加工为例，介绍了用户宏程序在圆弧形螺纹加工中的应用。文中较为详细地阐述了圆弧形螺纹在实际加工时数学表达式的建立方法以及宏程序在其中的应用技巧与注意事项等，并给出了相应的加工程序。希望对从事数控编程与操作的人员有一定的帮助和借鉴作用。     

The European maximum level for cadmium in bovine kidneys is in Belgium only realistic for cattle up to 2 years of age

The effect of animal age on concentrations of cadmium, lead, arsenic, copper and zinc in bovine tissues (meat, kidney and liver) sampled from animals reared in contaminated areas or reference regions in Belgium was investigated. For cadmium concentrations in meat samples analysis of variance (ANOVA) showed an increasing trend with age. In addition, a significant positive linear relation (p < 0.05) was found between animal age and renal (R ² = 0.56) or hepatic (R ² = 0.39) cadmium levels. Lead concentrations in kidneys and liver also increased with age, but the effect was blurred, likely due to the internal remobilization of lead. For the other trace elements (arsenic, copper, zinc) no relationship could be found between their concentration in meat, kidneys or liver and animal age. Renal cadmium concentrations were predicted for bovines at different ages by using the slope of the linear regression equation, and by taking into account its 95% confidence interval. Calculations for 2-year-old animals from reference areas showed that in this group the European maximum level of 1 mg kg^?1 for cadmium in kidneys would be exceeded in zero to 5% of cases. If a general rejection percentage of maximum 5% would be desirable for kidneys sampled in the reference areas (according to the ALARA principle–‘as low as reasonably achievable’–of European Union policy), then (1) kidneys from animals older than 2 years from the reference areas should a priori not be considered suitable to be placed on the market, or (2) the maximum level for cadmium in kidneys should be increased to 3 mg kg^?1. The latter would bear negligible risks for the general population and the majority of high-level kidney consumers. On the other hand, bovine kidneys from the most contaminated areas are not suitable to be brought into the food chain because it is predicted that the maximum level is already exceeded by more than 5% of the 1-year-old animals.     

铅冶炼烟气治理技术进步研究

铅冶炼烟气污染问题一直困扰着企业及相关部门，其治理已成当务之急。本文在总结评述国内外铅烟气治理技术进展的同时，探讨研究了铅烟气治理技术进步对策。     

Ferroelectric films of lead germanate prepared by modified chemical deposition techniques

Abstract

The high adhesive, single crystal lead germanate films of 5–105 μm in thick were fabricated on platinum substrates by in situ sol-gel technique. The stoichiometry of the films was closed to 5:3:11 without any oxygen deficiency. The microstructure of better films consisted of closed packed hexagonal crystals of 200–300 μm in size. Ferroelectric transition was sharp with Curie point 170–180°C, ε₂₀=30–40, tgδ₂₀?0.02, ε_max?200, P_s=3.2 μC/cm², E_c=16 kV/cm, ρ=10⁸–10⁹ Ωcm. All these parameters (with the exception of ε_max) were in a good agreement with bulk single crystals ones.     

铅黄铜阀体开裂原因分析

HPb59-1铅黄铜热锻产品在后期加工过程中出现大量开裂现象,采用金相及电子探针分析方法对HPb59-1铅黄铜阀体开裂原因进行分析.结果发现:铅黄铜阀体材质铅含量较高,显微组织分布不均匀,晶粒粗大;断口表面除含有大量富Pb的腐蚀产物外,还存在明显的高Pb和S元素的富集区.表明,热锻造过程中操作不当,退火不充分及腐蚀介质的存在,从而造成阀体的应力腐蚀开裂.     

立德粉生产中副产物的综合利用

介绍了立德粉生产中的副产物废铅泥、含锌镉渣、钡渣及生产废水的若干种综合利用方法及其原因、特点和效果。