WU Wei
,
MENG Hua-dong
,
LIU Liu
,
YUAN Tian-xiang
,
BAI Yan-jiang
,
YAN Zhan-hui
钢铁研究学报(英文版)
The slag melting characteristic of slag forming and slag splashing for 300 t BOF less slag process is researched by combining the methods of the slag chemical composition, the melting point determination and the petrographic analysis. The results show that the melting point of final slag for less slag smelting is 20 ℃ lower than that for conventional smelting. According to results of the petrographic analysis, the C3S (3CaO·SiO2) and C2S (2CaO·SiO2) content for less slag smelting are lower than those for conventional smelting, while the RO (FeO, MgO, MnO, etc) phase and C4AF (4CaO·Al2O3·Fe2O3) phase are higher than those for conventional smelting. According to results of the chemical analysis, the (CaO) content and slag basicity for less slag smelting are higher than those for conventional smelting, while (FeO) and (MgO) content in slag for less slag smelting are almost equal to those for conventional smelting. The reason why slag melting point for less slag smelting is lower than that for conventional smelting is that the quantity of added fluorite for less slag smelting is more than that for conventional smelting. According to the analysis results the slag melting point is determined by the C3S, C2S, RO phase and C4AF content. According to the results of slag melting characteristic before and after slag splashing for less slag smelting, the present adjusting slag process has little effect. It is important to adjust the composition of BOF final slag. The (FeO) content in slag is to be reduced at the slag splashing and adjusting slag process for less slag smelting.
关键词:
less slag smelting
,
melting point determination
,
petrographic analysis
,
slag forming process
,
slag splashing
Transactions of Nonferrous Metals Society of China
A new process for the hydrometallurgy of refractory gold concentrates was presented. The process comprises grinding-leaching, intensified alkaline leaching (IAL), cyanidation and adsorption. In a stirring-type pulverizing-leaching tower mill, the concentrate is ground to <35. 6 μm of 95. 5 % while simultaneously leached by NaOH of 12 kg/t, then carried out intensified alkaline leaching for 48 h by NaOH of 108 kg/t in enhanced agitation tanks with the pulp concentration of 40% solids at the environmental temperature of 9. 5 &SIM; 13. 5 &DEG;C and the environmental pressure of 10(5) Pa. The oxidation rate of As is 94. 9%, and 47. 6% for S. The total consumption of NaOH is only 20% of that theoretically calculated under the conditions of full oxidation at the same oxidation rates of arsenic to arsenate and sulfur to sulfate. The gold leaching rate by NaCN in 24 h is increased from 9. 2% before pretreatment to 94. 2%. The consumption of NaCN is 7. 5 kg/t, which is one times less than that before pretreatment. The extraction cost of gold is about 422 Yuan/t.
关键词:
refractory gold concentrates;grinding-leaching;intensified alkaline;leaching (IAL);pretreatment;common temperature and pressure
李林
,
林坚
,
李筱玉
,
王爱琴
,
王晓东
,
张涛
催化学报
doi:10.1016/S1872-2067(16)62578-0
多相催化反应过程伴随着反应分子与催化剂表面之间的相互作用.这种相互作用强度与催化剂的反应性能密切相关.根据萨巴蒂尔原理(Sabatier principle),性能最优的催化剂与反应中间体之间应该具有适中的相互作用强度,一方面促进反应物活化,另一方面允许产物脱附.这样,测量和研究反应分子与催化剂之间的相互作用强度对于理解催化反应性能有非常重要的意义.当气体反应物接触到催化剂表面会伴随着热量的产生,该热量被定义为吸附热,并与吸附物种与催化剂之间形成的化学键强度直接相关.吸附热通常可以通过程序升温脱附(TPD)等方法间接获得.但是这些方法建立在吸附物种能够可逆地吸附和脱附的假设基础上.在实际的程序升温过程中,吸附物种通常会发生分解,并伴随着固体催化剂的重构等现象.因此,采用基于Tian-Calvet原理的热流量热计直接测量担载催化剂的吸附热是最可靠的吸附热测量方法.基于热流量热计测量的微量热技术的一个重要优点是采用合适的探针分子吸附,可以获得担载型催化剂表面吸附活性中心的数量、强度及其能量分布的定量信息.比如,采用碱性探针分子NH3或者吡啶,酸性探针分子CO2或SO2能够定量催化剂上酸-碱位的强度和数量,而金属催化剂活性中心可以应用H2或CO进行探测.当这些催化剂活性中心的定量表征结果与催化剂的反应活性测试结果相关联时,可以区分不同强度活性中心的反应性能,并为提高和改进催化剂性能提供研制方向.相对于NH3或CO等小分子气体,催化反应的反应物、产物或可能的中间体通常都是复杂分子,程序升温技术测量它们的吸附热时,这些分子通常会发生分解,限制了其吸附热的测量和研究.微量热技术能够直接测量这些分子的吸附热.因此,与催化反应活性相关联,反应物、产物或可能的中间体的吸附能量的测量和研究有利于更直接地认识催化剂的反应性能.在催化反应循环过程中,除了吸附,还包括表面反应和脱附步骤.这些步骤也伴随着吸附物种与催化剂之间键的形成与转换,并以热量的形式表现出来.测量这些热量对于认识催化反应过程,理解催化反应机理有重要的意义.热流量热计与催化微反系统相结合,为催化反应过程能量的测量和研究提供了可能.尽管微量热技术在测量担载型催化剂的吸附/反应能量并与反应性能相关联方面有其独特的优势,但是为了更好地用于催化研究,应该结合其它的表征技术(比如红外)确定吸附或反应物种的本质,结合理论计算对量热结果进行更好地补充和认识.本文综述了担载型催化剂的吸附/反应能量与反应性能关联的研究进展,指出了微量热技术在催化研究中的优势、不足,以及未来的研究方向.
关键词:
催化
,
微量热
,
反应性能
,
能量
,
键强
,
催化剂表征
