【作者】 陈家武；

【导师】 高从堦； 肖连生；

【作者基本信息】 中南大学 ， 有色金属冶金， 2012， 博士

【摘要】 对于含有多种金属、多种矿物成分的胶态碳质镍钼矿,通常用高温焙烧的方法冶炼。而氧化焙烧不仅高耗能,且污染严重,还造成资源的巨大浪费。采用化学浸出法浸出镍钼矿也有不少尝试,但效果很有限,且成本很高。近十年来,微生物冶金技术开始应用于硫化矿的浸出,在硫化铜矿等多种矿物取得了成功,有的还进行了规模化生产。对于钼矿的生物浸出,也有许多探索性研究,但都局限于氧化亚铁硫杆菌等常温菌的常规浸出研究。以往研究发现,钼对常温细菌产生很强的毒性,导致浸出效果很差。为了解决浸出过程中的钼中毒问题,本研究采用对钼具有一定耐受性的古生嗜热菌---金属硫叶菌作为浸矿菌种,对镍钼矿进行了多种情形下的摇瓶浸出,然后结合膜技术和离子交换技术将矿在MBR系统中进行浸出研究。研究结果表明：1、金属硫叶菌在一定程度的驯化后,该菌对钼的耐受能力可以达到接近400mg/L,对镍的耐受浓度可以达到950mg/L左右。有较强的氧化亚铁的能力,也有能将元素硫氧化成硫酸的能力。是一种比较理想的浸出碳质复杂镍钼矿的嗜热古生菌种。2、镍钼矿的无菌浸出和有菌浸出有明显差别,后者的镍和钼的浸出率比前者高许多,分别达到91.78%和65.98%(而无菌浸出时镍和钼的浸出率分别为77.64%和50.19%)。对浸出过程中有菌和无菌浸样的矿物进行表面电镜观察,发现无菌浸出的矿物表面很光滑,而细菌浸出的矿粒表面存在大量的细菌活动的“腐蚀坑”,说明细菌对矿物的浸出是表面腐蚀作用。此外,嗜热金属硫叶菌和中温氧化亚铁硫杆菌对镍钼矿的浸出对比实验结果表明,前者镍和钼的浸出率分别达到93.17%和73.52%,高于后者的67.34%和38.36%。3.在用透析袋将细菌与矿物隔离的浸出实验中发现,镍和钼的浸出率分别为75.86%和54.69%,而同等条件下非透析处理的镍、钼浸出率则达到95.30%和63.46%。可见金属硫叶菌对镍钼矿的浸出过程中,细菌与矿物的接触是必要的。通过细菌与矿物的接触,细菌将矿物周围的SO氧化成SO42-而将硫膜不断清除,从而消除了Fe3+、Fe2+进出矿物表面的障碍。在浸出过程中,细菌的另一个重要作用是将浸出液中的Fe2+不断地氧化成Fe3+,而Fe3+是镍钼矿的重要浸出剂。4、实验表明,Fe3+是镍钼矿的重要氧化剂,但并非Fe3+浓度越高,镍钼矿的镍和钼浸出率越高。当浸出液中的Fe3+浓度超过4.0g/L之后,浸出率不再升高。这表明,在一定Fe3+浓度范围内,矿物镍和钼的浸出率除受到浸出液Fe3+浓度的影响外,还受到电位以及矿物的原电池效应的影响。由于浸出液的电位不高(500mv左右),加上矿物中钼与矿物中铜等金属离子形成原电池,因此,钼的浸出率较低,浸出速度也相对较慢。5、矿浆浓度、pH、矿物粒径、细菌接种量等因素对镍钼矿中镍和钼的浸出率影响较大。矿浆浓度与浸出率呈负相关；浸出需在酸性条件下进行,初始pH=2时,浸出效果最好；矿物粒径越小,镍和钼的浸出率越高；细菌接种量有一个最佳点,以10%(v/v)接种量的浸矿效果最好。较好的细菌浸矿条件为：温度65℃,接种量为10%,初始pH=2,矿物粒径0.048mm,矿浆浓度5g·L-。镍和钼的浸出率分别为99.97%和85.29%。6、进行了金属硫叶菌对低品位辉钼矿的浸出。在相同的浸出条件,辉钼矿比镍钼矿的浸出效果差得多。这可能是由于镍钼矿含有更多的硫、铁及碳等有利于细菌浸出的元素以及镍钼矿的特殊结构有关。说明金属硫叶菌更适合镍钼矿的浸出。7、通过MBR对镍钼矿的浸出发现,以超滤系统膜的截留作用使钼离开浸出液而细菌留下,可以控制浸出液的钼浓度和保持细菌浓度。当温度65℃,pH=2,矿浆浓度达到10%时,浸出时间20d,浸出过程中用MBR将浸出液的钼控制在接近395mg/L,此条件下镍和钼浸出率分别达到了79.57%和56.23%,比同等条件下的柱浸效果好。说明在较高钼浓度下采用MBR浸出是有利的。但钼浓度分别控制在≤160mg/L、≤250mg/L、≤300mg/L、≤350mg/L)的较低水平时,镍和钼的浸出率均不理想,因为低水平钼的控制,超滤走的浸出液量较大,导致其中Fe3+的损失而影响了镍和钼的浸出率。当浸出液钼浓度被控制在较低水平时,采用MBR是不合适的。8、为了达到既能控制浸出液中钼浓度又能保留其中的Fe3+,进行了MBR与离子交换结合的细菌浸出实验,将超滤后的浸出液经离子交换吸附钼后再返回浸出体系。但实验发现,树脂吸附钼也能部分吸附Fe3+,因此,在超滤-离子交换处理浸出液时,浸出液的处理量较大时,同样出现浸出液中的Fe3+损失问题,即造成Fe3+被吸附而离开浸出体系,从而影响浸出率。实验发现,将35%、18%和10%的浸出液经超滤-离子交换处理时,10%的处理量产生了较好的浸出效果。对镍钼矿的细菌浸出进行了动力学分析和热力学分析。探明了细菌浸出过程中镍和钼浓度随时间变化而变化的关系曲线以及Fe3+/Fe2+变化情况。并利用该矿物相关热力学关系式绘制了Ni,Mo-S-H2O pH-电位图。上述研究工作,对低品位矿物资源的可持续利用具有重要意义。更多还原

【Abstract】 The traditional metallurgical methods for nickel-molybdenum sulfide ore (jordisite) with several metal and various mineral components including carbon was roasting at high temperature. However, roasting not only is energy intensive,, but also brings serious pollution. Futhermore, traditional roasting results in huge waste of natural resource. Great effort has been made in the application chemical method, but with limited achievement-It is also found to be a high-cost approach. In past decade, application of bio-metallurgical technology in the extraction of sulphide ore raises much attention. It has been successfully employed in the metallurgy of many metallic sulphide (e.g. copper sulfide) and mass production has been actualized in some fields. Regarding bioleahcing of molybdenum mineral, a lot of exploratory researches have been conducted. Nevertheless,most of them focused on ordinary bacterias such as Thiobacillus ferrooxidans.Investigation demonstrated that the toxic inhibition of Molybdenum toward ordinary bacterias result in very low bioleaching efficiency. In view of this situation, sulfolobus metallicus, a type of acidophilic thermophile microorganins that can tolerate the toxicity of molybdenum to some degree. Bioleaching in shaking flasks and in membrane reactor combined with ion-exchange was studied. The following results were obtainedThe experimental results showed that sulfolobus metallicus, as the leaching bacteria, has strong ability to oxidize the ferrous component as well as convert S0into sulphuric acid (H2SO4). After cultivation, this type of microorganism could endure up to400mg/L of molybdenum and950mg/L of nickel. Therefore, sulfolobus metallicus was a good candidate for leaching nickel-molybdenum ore known as Mo-S-C composite.There was marked difference in the leaching rate of Ni and Mo between the leaching with and without sulfolobus metallicus;the latter was91.78%and65.98%respectively,while the former was just77.64%and50.19%. The microorganism existing on the partical surface played an important role in the bioleaching process, which was proved by other experiments including the scanning electron microscope (SEM)analysis of the surface of particles subjected to the leaching process. For the leaching with sulfolobus metallics, a lot of corroded holes were observed on the surface of the mineral particles; while especially smooth surface was observed with the particles in the leaching as control.Furthermore, there were a lot of microorganisms absorbed on the surface of the mineral particle in the former group. The bioleaching rate of Ni and Mo was distinctly improved after the strain was acclimated and induced.In addition, the leaching comparision showed that the leaching rate of Ni and Mo with sulfolobus metallicus was higher than the Thiobacillus ferrooxidans.when dialysis bag was put between the mineral and microorganism, the leaching rate of Ni and Mo was75.86%and54.69%,which were low than that of the control group without dialysis bag(95.30%and63.46%in this group). The possible reason is that S0on the surface of the mineral particle was continuously oxidized into H2SO4by sulfolobus metallicus and the S0membrane as the barrier between the mineral particle and leaching liquid was removed. Another important role of sulfolobus metallicus was to oxidize Fe2+into Fe3+that act as lixiviant for the solubilization of nickel andmolybdenum from sulfide ore.Inspite of its critical role, higher Fe3+concentration does not necessarily lead to more efficient leaching of Ni and Mo. The leaching rate did not increase when Fe3+concentration reached4.0g/L. It is concluded that the leahcing rate of Ni and Mo is influenced not only by the concentration of Fe3+but also by other factors including electric potential and primary battery effect of the metal ion in nickel-molybdenum sulfide ore. Due to its low electric potential and battery effect compared with the other metal ions such as copper in nickel-molybdenum sulfide ore molybdenum at negative pole is protected and its leaching rate was low.The impact of mineral density, pH, mineral particle and inoculation on the bioleaching rate of Ni and Mo were obviously. Mineral density was inverse relation to the leaching rate, and there was the best leaching rate of Ni and Mo,which reached99.97%and85.29%respectively under the condition of5g·L-1mineral density and initial pH=2. In addition, the less mineral particle,the more the leaching rate of Ni and Mo at the same mineral density. The experiment also revealed that the10%inoculation was the best favorable bioleaching among several group of the different inoculation.The bad result of the bioleaching on MoS2with sulfolobus metallicus reflected that there was different structure and component between nickel-molybdenum sulfide ore and MoS2so that the Mo was leached out in different leaching rate,in which the special structure of ore of C-Ni-Mo-S was further revealed.The bioleaching of nickel-molybdenum sulfide ore in MBR showed that ultra-filter could put the concentration of Mo under control by filter at regular intervals. When the concentration of Mo in MBR with sulfolobus metallicus was controlled near and under395mg/L,the leaching rate of Ni and Mo was79.57%and56.23%respectively,which reached the best among all group and exceeded the group of column leaching. The leaching rate of Ni and Mo in others group including the group of Mo<160mg/L,<250mg/L,<300mg/L,<350mg/L were all less than the group of Mo<395mg/L since a lot of Fe3+was carried away when the leaching liquid was filtered out.Therefore, Both the concentration of Mo and loss of Fe3+in the leaching liquid should be considered in MBR with sulfolobus metallicus.While the membrane was necessary in order to reach such a tuation.Otherwise,the concentration of Mo in leaching liquid will be rise till restrain the growth of micorganism.This paper used MBR conbined ion-exchange in order both to control Mo and to avoid the loss of Fe3+and retrieve the leaching liquid being exchanged.But Fe3+in leaching liquid was still partly absorbed and exchanged by resin so that the leaching rate of Ni and Mo was decreased by the loss of Fe3+when the excessive leaching liquid was filtered and exchanged. The leaching rate of Ni and Mo in the group which10%of the leaching liquid was filtered and exchanged was79.53%and56.52%which was the climax among all group including 35%and18%of leaching liquid being filtered and exchanged.lt will be favorable to MBR conbined ion-exchanged for the bioleachng of nickel-molybdenum sulfide ore especially with ordinary microorganism if a resin could be made for exclussive Mo absorption.At last, dynamics was studied according to the change of Fe3+/Fe2+and the concentration change of Ni and Mo in process of bioleaching.At the same time, themodynamics analyse was made through the drawing of Ni,Mo-S-H2O pH-E.The study mentioned above will play an important role in sustainable development of metallurgical industry at low degree mineral resource.更多还原