Mössbauer study of the thermal decomposition of FeS2 in coal

The Mössbauer effect has been used to study the transformations of FeS₂ in four different coals: IL No. 6, Ky $\text{9}\text{14}$, Blacksville No. 2, and Powhatan No. 5. The transformations of FeS₂ in the coals were studied in an inert atmosphere. It was observed that the pyrrhotites formed from FeS₂ have a considerable reduction in the isomer shift at 440 °C as compared to the values obtained in the absence of coal. This effect is associated with the interaction of the pyrrhotites with the coal constituents at high temperatures. There is also a significant line-broadening at 440 °C. This broadening is due either to vacancy motion in the iron sulphides and/or to motional broadening due to particle motion in the coal-derived liquids. The percentage conversion of pyrite to pyrrhotite depends markedly on time as well as type of coal. The weathering of the coal has a detrimental effect on the rate of conversion of pyrite to pyrrhotite. The ferrous sulphate layers covering the pyrite particles hinder the removal of sulphur from that surface. The major factor affecting the $\text{Fe}\text{S}$ ratio is the total amount of sulphur available for H₂S formation. Partial H₂S pressure is the crucial quantity controlling the stoichiometry of the pyrrhotites. Hence, a high percentage of H₂S in the reactor at high temperature will assure the formation of pyrrhotites with a high number of metal vacancies.     

400kt／a硫铁矿制酸装置挖潜扩能改造

介绍400 k t/a硫铁矿制酸装置的挖潜改造。通过调整工艺技术指标,增加少量设备和催化剂,将硫酸装置的生产能力从400 k t/a提高到450 k t/a,改造后各项技术经济指标均达到要求,2005年第1季度实现利润1 479万元,取得了明显的经济效益。     

草分枝杆菌选择性絮凝脱除煤中黄铁矿硫的研究

对疏水性微生物草分枝杆菌(M．phlei)进行培养，并结合红外光谱分析，研究了草分枝杆菌(M．phlei)的生物学特性及对煤的絮凝作用．试验结果表明，草分枝杆菌(M．phlei)可选择性地吸附作用于煤表面，在实现对煤絮凝的同时，能较有效地脱除煤中的黄铁矿硫．     

Electron spin resonance from impurities in coal-derived pyrites

The first observation of several e.s.r. lines in coal-derived pyrites (FeS₂) is reported. These lines are due to Mn²⁺ impurities in FeS₂ and to free radicals in coal kerogens associated with pyrites as inclusions.     

Decomposition of pyrite under coal liquefaction conditions: A kinetic study

The decomposition of FeS₂, both as a single phase and as it exists in coal, has been studied between 250 and 350 °C, in hydrogen and nitrogen atmospheres, and in the presence of a coal-derived solvent. The first-order rate constant for decomposition of FeS₂ at 350 °C with H₂ alone is 6.7 × 10^?1min^?1; with H₂ and coal-derived solvent, it is 5.5 × 10^?2min^?1; for FeS₂ contained within coal, solvent and H₂, it is 8.6 × 10^?3min^?1. Although the rate constant for decomposition is dependent upon temperature and the system, the activation energy in each case has been calculated to be 88 kJ mol^?1. A mechanism consistent with these data is the thermal decomposition of FeS₂ to produce Fe_1?xS and S, followed by reaction of the sulphur with available hydrogen (from H₂, solvent or coal) to form H₂S.     

氢化物发生-原子荧光光度法检测硫铁矿和硫精矿中砷含量

用硝酸-氯酸钾溶样,氢化物发生-原子荧光光度法检测硫铁矿和硫精矿中砷含量,方法检出限0．2281ttg／L,加标回收率在90．1％-102．3％之间。该法为硫铁矿和硫精矿中砷含量提供了一个灵敏度高、方便快捷的新方法。     

提高选择性絮凝脱硫效果的途径

本文讨论了矿浆浓度、矿浆、PH值、絮凝剂与煤样作用时间和煤系黄铁矿抑制剂对选择性絮凝脱硫效果的影响,并提出了提高选择性脱硫效果的方法。     

低碱度下组合抑制剂对易浮黄铁矿的抑制机理研究

针对某铅锌矿长期采用大量石灰调浆, 以高碱工艺抑锌硫浮铅而产生的诸多弊端, 通过一系列试验, 确定了一种组合抑制剂, 在低碱度条件下实现了铅硫分离。通过对实际矿石的校核试验, 说明采用该组合抑制剂在低碱度(pH =9左右)矿浆条件下所获得的铅矿物选别指标可以与高碱工艺相当。     

灰分和黄铁矿对燃煤NO和SO2生成的影响

研究了酸洗对煤粉燃烧过程中NO和SO2生成的影响。分别对黄台煤和阳泉煤进行了HCl+HF酸洗和HNO3酸洗处理,在800℃、950℃和1100℃等3个温度工况测取和分析原煤和酸洗煤燃烧生成的NO和SO2。研究表明:经过HCl+HF酸洗去灰处理后的两种煤,NO生成量明显降低,SO2生成量有所增加;对HCl+HF酸洗去灰处理后的煤再进行HNO3酸洗脱黄铁矿处理,由于HNO3酸洗过程中掺杂了一定量的硝酸基,所以对洗煤又进行了两次去硝酸基处理,最终得出3个温度工况下NO生成量均降低,SO2生成量也明显降低。     

硫铁矿和硫磺制酸的比较

对2kt／d硫铁矿制酸与硫磺制酸装置的原料经济性、原料品质、工艺差别、设备及装置成本进行了详细比较。主要探讨在作出一项新的投资决策时经济性与工艺之问的基本权衡。一般倾向于使用市售硫磺作为硫酸生产原料,因为其投资要低很多,而且工艺过程更加简单可靠,但有些国家由于拥有大量的硫铁矿资源,且税收结构、关税、政府津贴、采矿和运输成本均对使用硫铁矿有利,可考虑使用硫铁矿作为原料。