【作者】 杨晓娟；

【导师】 李红玉；

【作者基本信息】 兰州大学 ， 生物化学与分子生物学， 2008， 硕士

【摘要】 传统的生物浸出工艺由于浸出周期长,浸出率低等因素,已经越来越不能满足冶金工业发展的需要。基于生物浸出的联合作用机理,本文设计了一种生化两极循环反应工艺,该工艺将传统的矿物生物浸出过程分为细菌生长,Fe²⁺的细菌氧化的生物反应过程以及细菌氧化产物有矿物间的化学反应过程。该工艺流程为:在生物反应器中Fe²⁺被At.f氧化为Fe³⁺,Fe³⁺通过恒流泵进入化学反应器,并与其中的硫化矿进行反应产生Fe²⁺,然后这些Fe²⁺又进入生物反应器被At.f氧化为Fe³⁺,其后这些Fe³⁺又被带入化学反应器,如此往复循环。该工艺的主要特点是:第一,可以分别化学反应过程和生物反应过程进行强化,以便提高硫化矿的浸出率;第二,利用生物反应器中的At.f可以不断地产生Fe³⁺。在对化学反应过程采取强化措施时,发现升高温度,增加Fe³⁺和添加Cl^-都有利于镍硫化矿的浸出,考虑到成本因素,决定把T=50℃,[Fe³⁺]=9g/L,Cl^-=3.8 g/L做为最佳的化学浸出硫化矿的工艺参数。因为固定化At.f可以增加细菌浓度,提高Fe³⁺的形成速率,提供丰富的氧化剂,于是尝试采用PVA冷冻法固定At.f,但是固定化At.f由于其丰富的表面积将产生大量的黄铁矾沉淀,减少了作为氧化剂的Fe³⁺,因此在用生化两极循环反应处理镍硫化矿时,固定化At.f比游离At.f的浸出率低。为了既能利用固定化所提供的快速的Fe²⁺氧化速率,又能降低黄铁矾沉淀所带来的负面影响。本文通过降低pH值,减少（NH₄）₂SO₄来减少黄铁矾,但即使黄铁矾沉淀得到一定程度的减少,其黄铁矾沉淀的生成量也远远大于培养游离At.f所产生的沉淀。因此,本项目决定采用游离At.f来浸出硫化矿。当[Fe³⁺]=9 g/L,Cl^-=3.8g/L,生物反应器T=30℃,化学反应器T=50℃,生化两极循坏浸出硫化矿工艺在浸出周期为9天,矿浆浓度为5%,该工艺的镍浸出率为60%。为了尽量缩短浸出时间,又对化学反应器采取了气体搅拌的强化措施,在维持相同的操作参数的条件下,经过5天,镍黄铁矿的浸出率就达到了83.8%,明显高于无菌组和30℃对照组的浸出结果。然而,当这种工艺用于浸出白银黄铜矿,经过5天,黄铜矿的浸出率仍然低于20%,这主要是因为镍黄铁矿的间接浸出主要是通过硫代硫酸盐实现的,而黄铜矿主要是通过多聚硫化物和单质硫实现的,这层惰性膜会阻碍Fe³⁺和矿物的接触,对于这类矿物,需要提高温度至80℃以上。更多还原

【Abstract】 With the development of technology and because of the long leaching period and low leaching rate,the traditional bioleaching process needs to be reformed.Based on the cooperative leaching mechanism,a new bioleaching process comprising biooxidation and chemical leaching is proposed.The principle of this whole process can be summarized as follows:firstly the leaching solution in the chemical reactor would react with sulfide to produce Fe²⁺,then the Fe²⁺passed to bioreactor would be biologically oxidized to ferric ions which subsequently be recycled to chemical reactor by a HL-2S peristaltic pump reacting with the sulphide minerals again.The process features the continuous production of ferric and the respective improvement of chemical and biological process.The ferric leaching of pentlandite was favored by the rise of temperature,the increase of Fe³⁺which is in constant with the indirect mechanism,and the partial replacement of SO₄^2-with Cl^-.In view of the cost,T=50℃,[Fe³⁺]=9 g/L,Cl^-=3.8 g/L were selected as the optimal parameters for the biological-chemical leaching process.Because immobilized At.f could increase the number of microorganism,accelerate the formation rate of Fe³⁺.But immobilized cell would lead to the formation of a lot of jarosite,which decrease the quantity of Fe³⁺.Thus the leaching rate of Ni by immobilized At.f is lower than the leaching rate of Ni by free At.f.In order to utilize the high Fe²⁺oxidation rate by immobilized At.f,the decrease of pH value and the concentration of（NH₄）₂ SO₄ was tried to decline the formation rate of jarosite.And the results showed that the formation rate of jarosite by immobilized At.f is still higher than the free At.f even though the formation rat of jarosite by immobilized At.f is lowed at certain extent.When the chemical reactor was not stirred,with a pulp density of 5%and temperature of 50℃in chemical reactor,a leaching rate of 60%was achieved at 9 days by this biological-chemical process.So in order to further enhance the leaching efficiency,stirring the leaching rate by air was also tried.Under the same conditions,the leaching rate of this alternative was 83.8%at 5 days.However,the leaching rate of chalcopyrite by the biological-chemical process was not satisfactory,which can be attributed to the formation of an inert film which is different from sulfur film which is produced for the leaching of pentlandite.This inert film was not stable until with a temperature above 80℃.更多还原