Effects of anion and cation doping on the thermoelectric properties of n-type PbS

The PbCl_xS_1-x and Pb_1-xBi_xS (x? =?0–0.05) bulks were fabricated with a facile method of hydrothermal synthesis and microwave sintering, and the effect of anionic and cationic donors on the thermoelectric performance of PbS was investigated. Although Cl^? and Bi³⁺ both effectively improved the thermoelectric properties of n-type PbS, more excellent thermoelectric performance was obtained from Cl^? doped samples because of higher electrical property and lower thermal conductivity at higher temperature (T? >?600?K). The thermoelectric figure of merit (ZT) reaches 1.04 for PbCl_0.015S_0.985 at 800?K and increases with temperature increasing without sign of saturation, which is probably the highest value ever reported for single-phase polycrystalline n-type PbS. The results also indicate that the hydrothermal synthesis and microwave sintering can realize anion doping as well as cation doping for n-type PbS at low cost, and PbS should be a robust alternative for PbTe thermoelectric materials.     

三种硫化氢吸收剂吸收效率对比及碘酸钾体系吸收条件优化研究

硫化氢具有腐蚀性与毒性，采用吸收剂吸收硫化氢气体是重要的脱硫处理方式。不同的吸收剂在吸收效率上存在较大差别。首先对比了三氯化铁体系、碘酸钾体系和碱性铁氰化钾体系三种不同硫化氢吸收剂的吸收效率。在此基础上重点优化了碘酸钾体系吸收条件参数，讨论了包含浓度、温度、pH、气体流量及时间等因素对硫化氢吸收效率的影响。并建立了四因素三水平正交试验研究较优吸收条件，得到正交试验优化吸收条件为：温度55℃，pH 6.01，硫化氢流量0.3 L·min^-1，吸收时间1 min，该条件下8%（质量）碘酸钾体系的三级吸收效率为51.56%。研究结果对硫化氢吸收处理提供了理论参考，也为间接电解法循环处理研究提供了支持。     

Iron(II) Sulfate(VI) from Titania Production as a Raw Material for Preparation of Hydrogen Sulfide Sorbents

A hybrid sorbent material for removal of hydrogen sulfide from air was developed. The material is based on activated carbon and iron compounds obtained from waste iron(II) sulfate(VI) heptahydrate. The iron salt is deposited on the carbonaceous support and subjected to oxidation (Fe²⁺ to Fe³⁺) using atmospheric oxygen under alkaline conditions. An effect of H₂O₂ addition to the process on the composition of the resultant material was also examined. X-ray diffraction (XRD) analyses confirmed easy conversion of waste FeSO₄·7H₂O to iron oxides Fe₃O₄ and FeOOH. The activated carbon supporting iron oxides revealed a higher efficiency in H₂S elimination from air compared to the commercial activated carbon, without any modification.     

某铜铅锌多金属硫化矿选矿试验研究

对某富含金银等贵金属的复杂铜铅锌多金属硫化矿进行了选矿试验研究。以BK916作铜捕收剂、BK906作铅捕收剂, 采用铜优先浮选-铅浮选-锌硫混合浮选-锌硫分离工艺回收主要有价元素, 获得了铜精矿铜品位24.26%、回收率58.21%, 铅精矿铅品位70.75%、铅回收率86.55%, 锌精矿锌品位51.53%、锌回收率89.44%, 硫精矿硫品位39.84%、回收率38.03%的良好选矿指标; 铜、铅、锌、硫4种精矿产品中金总回收率92.16%、银总回收率89.44%。     

某复杂铜硫矿浮选分离与综合回收试验研究

某复杂铜硫矿原矿硫铁含量高,现场为高碱工艺流程,铜硫分离困难且金银综合回收效率低。采用硫化钠预先活化,“石灰+羧化壳聚糖”作黄铁矿和磁黄铁矿抑制剂,粗选pH=8.5,经一粗两精三扫优先浮选流程可得到含铜24.63%、含金3.41 g/t、含银952.05 g/t,铜回收率84.45%、金回收率32.58%、银回收率75.70%的铜精矿。羧化壳聚糖为清洁高效有机高分子化合物,能高效选择性抑制硫铁矿,在提高主金属铜回收率的同时,伴生金银矿物得到了高效综合回收。     

C38+N2非调质钢曲轴法兰开裂原因分析

某厂的C38+N2非调质钢曲轴,在装机测试压力时法兰部位开裂。通过化学成分分析、金相检验、断口检验、能谱分析及硫印试验等研究了曲轴开裂的原因。分析结果如下:①材料化学成分和法兰部位淬硬层深度均符合要求;②断口上部为准解理断裂,下部为“朽木状”撕裂;③在锻造分模面有硫化物聚集,甚至有长达1mm的以MnS为主的超长硫化物。硫化物聚集割裂基体材料是曲轴开裂的主要原因,曲轴锻后晶粒粗大,法兰的螺孔部位厚度较薄,是其开裂的次要原因。     

铜冶炼电收尘灰浸出液与硫化砷渣综合处理工艺研究

介绍了一种铜冶炼电收尘灰酸浸液与硫化砷渣的联合处理工艺。确定了铜冶炼电收尘灰浸出液与硫化砷渣最佳反应条件为:加入硫酸铜量为理论铜与砷摩尔比1.1∶1,反应温度85℃,反应时间2 h,铜离子质量浓度15 g/L,初始硫酸质量浓度30 g/L。     

基于双转子连续混炼挤出机的PPS/CF复合材料制备及性能研究

采用双转子连续混炼挤出机并通过熔融共混法制备了碳纤维(CF)增强聚苯硫醚(PPS)复合材料，并对其微观形貌、动态力学性能、力学性能和导电性能进行了研究，且对相关的影响因素进行了分析。结果表明，适当降低挤出机转子转速、提高CF含量可以改善PPS/CF复合材料的力学性能和导电性能；当转子转速为200r/min时，采用含量为20 % (质量分数，下同)的CF制得的PPS/CF复合材料的冲击强度达到49.94 J/m，体积电阻率达到60.65 Ω·cm，均优于纯PPS。     

Physicochemical and environmental properties of arsenic sulfide sludge from copper and lead−zinc smelter

Physicochemical properties of arsenic sulfide sludge (ASS) from copper smelter (ASS-I) and lead−zinc smelter (ASS-II) were examined by XRD, Raman spectroscopy, SEM−EDS, TG−DTA, XPS and chemical phase analysis method. The toxicity characteristic leaching procedure (TCLP), Chinese standard leaching tests (CSLT), three-stage sequential extraction procedure (BCR) and batch leaching experiments (BLE) were used to investigate the environmental stability. The ASSs from different smelters had obviously different physicochemical and environmental properties. The phase composition and micrograph analysis indicate that ASS-I mainly consists of super refined flocculent particles including amorphous arsenic sulfide adhered with amorphous sulfur and that ASS-II mainly consists of amorphous arsenic sulfide. The valence state of arsenic in both sludges is trivalent, but the valence composition of sulfur is quite different. The ASSs have thermal instability properties. The results of TCLP and CSLT indicate that the concentrations of As and Pd in the leaching solution exceed the standard limits. More than 5% and 90% of arsenic are in the form of acid soluble and oxidizable fractions, respectively, which explains the high arsenic leaching toxicity and environmental activity of ASS. This research provides comprehensive information for the disposal of ASS from copper and lead−zinc smelter.     

Deactivation of hydrodesulfurization catalysts during reactor startup

Metal sulfide catalysts for ultra-deep hydrodesulfurization of diesel generally lose a fraction of their catalytically active sites during reactor startup. The underlying mechanisms are discussed. A laboratory diagnostic tool consisting of three probe molecules is developed for testing metal sulfide catalysts' start-of-run (SOR) activity maintenance. It is found that a significant fraction of the active sites on a commercial supported catalyst are deactivated permanently, but this is not the case with a bulk metal sulfide catalyst. The SOR deactivation of the bulk catalyst is completely reversible, while that of the supported catalyst is partially reversible. The diagnostic tool may provide a basis for developing a high-throughput approach for evaluating and enhancing catalyst SOR stability, thereby increasing plant productivity.