熔融改质镍渣中磁铁矿相结晶行为的研究

发布时间：2018-05-05 07:45

  本文选题：镍渣 + 磁铁矿相　； 参考：《兰州理工大学》2017年硕士论文

【摘要】：镍渣是镍冶炼过程排放的一种工业废渣,含有铁、镍、钴、铜等多种有价金属。为了实现镍渣中铁资源的高效回收再利用,本课题以金川公司闪速炉水淬镍渣为研究对象,采用熔融改质氧化的方法,通过加入氧化钙对镍渣进行改质,通入空气进行弱氧化,控制降温及保温条件,使得镍渣中铁组元以磁铁矿相的形式析出,然后通过磁选将磁性物质与非磁性物质分离。本文研究了镍渣碱度、冷却速率、保温时间及保温温度对熔渣性能变化以及磁铁矿相晶体形貌的影响规律,建立了磁铁矿相析晶动力学模型,探索熔融改质镍渣中磁铁矿相的析出长大的行为。主要研究内容及结果如下:(1)通过对镍渣的成分及物相进行分析得知,Fe含量约为39.91%,同时含有少量的Ni、Co、Cu等有价金属。其中的主要物相为板条状的铁橄榄石相(Fe_2SiO_4)及铁镁橄榄石相[(Fe,Mg)SiO_4]。通过熔融改质氧化的方法可以实现镍渣中的铁以磁铁矿相(Fe_3O_4)的形式富集,且发现渣中的Ni、Co、Cu元素同时富集于磁铁矿相中。(2)通过加入改质剂氧化钙(CaO),研究了碱度对熔融改质镍渣中磁铁矿相析出与长大过程的影响规律。结果表明:适宜的碱度有利于磁铁矿相的析出长大,当碱度为0.6时,渣中的主要物相为磁铁矿相,呈不规则的颗粒状,分布较为均匀,且结晶量最大,可达到36.3%。(3)研究温控制度对磁铁矿相析出与长大过程的影响。结果表明:随着冷却速率的减小,氧化渣样中的物相组成没有明显变化,但磁铁矿相的晶粒尺寸和结晶量都明显增大,且晶体发育完整,晶界清晰,结合实际生产效率,冷却速率在3~5℃/min较为适宜。保温过程对磁铁矿相析出长大过程影响显著,随着保温时间的增长,熔渣长时间处于磁铁矿相的结晶温度范围内,使磁铁矿相有充分的时间析出长大,保温20min时,熔渣中磁铁矿相充分析出;随着保温温度的降低,磁铁矿相的结晶量逐渐增大,说明适宜的过冷度有利于磁铁矿相的析出,温度为1350℃时,磁铁矿相析出效果较好;在1350~1400℃,磁铁矿相等温结晶动力学过程可近似用JMAK经验方程描述,并通过方程可求得晶体生长指数n≈0.5,析晶活化能E=-178.3kJ/mol。
[Abstract]:Nickel slag is a kind of industrial waste slag discharged from nickel smelting process. It contains many valuable metals such as iron, nickel, cobalt, copper and so on. In order to realize the high efficiency recovery and reuse of iron resource in nickel slag, this paper takes the water quenched nickel slag of Jinchuan company as the research object, adopts the method of melting modification and oxidation, by adding calcium oxide to the nickel slag to improve the quality of the nickel slag, and enters the air for weak oxidation. By controlling the cooling and holding conditions, the iron component in the nickel slag is precipitated in the form of magnetite phase, and then the magnetic material is separated from the non-magnetic material by magnetic separation. In this paper, the effects of basicity, cooling rate, holding time and holding temperature of nickel slag on the properties of molten slag and the crystal morphology of magnetite phase are studied, and the kinetic model of crystallization of magnetite phase is established. The precipitation and growth behavior of magnetite phase in molten modified nickel slag was investigated. The main research contents and results are as follows: (1) by analyzing the composition and phase of nickel slag, it is found that the content of Fe is about 39.91, and a small amount of valuable metals such as NiCoCoCU are also found. Among them, the main phases are plate stripe olivine phase Fes _ 2SiO _ 4) and ferric olivine phase [Fe _ 2O _ (2) Si _ 2O _ 4] and Fe _ (2) O _ (2) O _ (4) (Fe _ (2) O _ (2)). The iron in nickel slag can be enriched in the form of magnetite phase Fe _ 3O _ 4 by means of melting modification and oxidation. It is also found that the Ni _ (Co) Cu element in the slag is enriched in the magnetite phase at the same time.) the effect of alkalinity on the precipitation and growth of the magnetite phase in the molten modified nickel slag was studied by adding the modifier calcium oxide and Cao _ (2). The results show that the suitable basicity is favorable to the precipitation and growth of magnetite phase. When the basicity is 0.6, the main phase in slag is magnetite phase, which is irregular granular, and the distribution is more uniform, and the crystallization amount is the largest. The effect of temperature control system on the precipitation and growth of magnetite phase is studied. The results show that with the decrease of cooling rate, there is no obvious change in the phase composition of the oxidized slag, but the grain size and crystallization amount of the magnetite phase increase obviously, the crystal development is complete, the grain boundary is clear, and the production efficiency is combined with the actual production. The cooling rate is suitable at 5 鈩，

本文编号：1846814