高压氢还原法制备Ni包SiC粉末的研究

采用高压氢还原法制备了Ni包SiC复合粉末,研究了反应温度、氢分压、表面活性剂及包覆次数对包覆效果的影响,并且对该包覆粉末的热稳定性进行了评价。结果表明:在反应温度为150~160℃、氢分压为1.5~2.5MPa、活性剂的质量浓度为0.05g/L、搅拌速度为800r/min的条件下,包覆二次可以获得连续均匀的包覆层。包覆粉末在1 150℃左右会发生反应,生成Ni2Si和C。     

Thermochemical decomposition of hydrogen sulfide with nickel sulfide

In this research, the two-step thermochemical cycle shown below is proposed and experimental studies were made on the cycle. $$\frac{\begin{gathered} {\text{Ni}}_{\text{3}} {\text{S}}_{\text{2}} + {\text{H}}_{\text{2}} {\text{S}} = {\text{3NiS + H}}_{\text{2}} \hfill \\ {\text{3NiS = Ni}}_{\text{3}} {\text{S}}_{\text{2}} {\text{ + 0}}{\text{.5S}}_{\text{2}} {\text{(g)}} \hfill \\ \end{gathered} }{{{\text{H}}_{\text{2}} {\text{S = H}}_{\text{2}} {\text{ + 0}}{\text{.5S}}_{\text{2}} {\text{(g)}}}}$$ In the case where Ni₃S₂ alone was used without inert additions, nickel sulfide sintered or partly fused due to the melting point depression resulting from the thermal decomposition of formed NiS. Such sintering could be prevented by mixing the nickel sulfide powders with Al₂O₃ or MoS₂. The cyclic reactions were thereby shown to provide a stationary high decomposition rate of H₂S. Polysulfides, such as MS₂, have previously been employed in this kind of cycle. This research showed that the use of lower sulfides such as Ni₃S₂ may be regarded as rather promising based on the thermodynamic investigation of the respective reactions composing the cycle. The comparison between the sulfurization reactions of NiS to NiS₂ and of Ni₃S₂ to NiS further showed that the latter was superior to the former with respect to the kinetics and thermodynamical properties of the reaction.     

硫化氢环境下氢扩散的影响因素

采用典型的电化学渗氢装置,对材料的化学成分、焊接和环境中CO₂和NH₄⁺的质量浓度、溶液的pH值对硫化氢应力腐蚀开裂中氢扩散行为的影响进行了研究.结果表明:金属中夹杂物数量、焊缝金属中空位和焊接缺陷使得氢扩散系数增加;在硫化氢环境中,氢扩散稳态电流随pH值的增加而降低,随着NH₄⁺的质量浓度的增加而增加,且增加幅度随着pH值的增加而加大;CO₂的质量浓度对氢稳态扩散电流的影响是随着pH值的变化而起着不同的作用,在低pH值条件下氢稳态扩散电流随着CO₂的质量浓度增加而增加,在较高的pH值中氢稳态扩散电流随着CO₂的质量浓度增加而减小.     

某高品位钼铋硫化矿选矿试验研究

内蒙古某钼铋多金属硫化矿,含钼0.65 %,含铋1.12 %,钼铋品位较高,有较大的工业回收价值.采用“混合浮选—钼铋分离”的选矿工艺回收该矿石中的有用矿物,以乙硫氮和煤油作为捕收剂进行混合浮选,以硫化钠和亚硫酸钠作为组合抑制剂,煤油为捕收剂进行钼铋分离,最终实验室小型闭路试验可以获得含钼47.31 %,钼回收率89.52 %的钼精矿以及含铋42.64 %,铋回收率86.04 %的铋精矿,较好地实现了钼铋分离.      

Single and complex effect of ammonia and hydrogen sulfide in the air on small laboratory animals (rats) under various environmental conditions 2. Effect of hydrogen sulfide alone and hydrogen sulfide with ammonia and dust

The maximum tolerable concentrations per animal position of hydrogen sulphide alone (5 ppm) and with ammonia (5 ppm H2S; 30 ppm NH3) were established by model experiments under defined environmental conditions. The normal values of the contaminant gas combination were found to be acceptable even with additional dust load on the experimental animals. TGL 29084 should stipulate 5 ppm hydrogen sulphide as the new maximum concentration per animal position.