以铀矿渣为载体联合PEG2000的细菌固定化培养

以铀矿渣为载体,采用逐次降低接种率循环培养的方法,开展了氧化亚铁硫杆菌的固定化培养试验,研究了聚乙二醇2000（PEG2000）对游离细菌和铀矿渣载体柱中固定化细菌生长的影响。试验结果表明：90 mg/L PEG2000对游离细菌的生长促进作用最大。铀矿渣和K3环材料均可作为载体进行细菌固定化培养。固定化完成时,其亚铁离子的平均氧化速率分别稳定在0.6和0.5 g/(L?h)附近。90 mg/L PEG2000对循环培养和连续培养阶段的固定化细菌生长均具有促进作用。循环培养阶段,可使Fe2+氧化为Fe3+的时间缩短约1/3。连续培养阶段,PEG2000能够促进固定化细菌对亚铁离子的氧化速率,在0.5 L/h进液流量时,未加PEG2000的亚铁离子氧化速率为7.04 g/(L?h),而加PEG2000的,达到了8.18 g/(L?h),亚铁离子氧化效率提高了16.2%。     

批次培养及连续培养制备硫酸高铁浸铀菌液的对比研究

采用批次培养和连续培养两种工艺开展浸铀硫酸高铁菌液的培养,对比分析了二者菌群的氧化活性、菌液Fe3+/ΣFe及日菌液产出比(日出液量与氧化槽容积比)的差异。结果表明,当总铁含量为10g/L、菌液批次培养和连续培养的Fe2+的氧化速率分别为0.20g/(L·h)及0.34g/(L·h)、控制菌液Fe3+/ΣFe为96%左右时,批次培养和连续培养的日菌液产出比分别为1.04和1.43;菌液连续培养的Fe2+氧化速率和日菌液产出比分别是批次培养的1.7倍和1.4倍。此硫酸高铁菌液最适接种条件为:pH=1.6~1.7、Fe3+/ΣFe为90%~95%。     

酸法地浸铀矿吸附尾液细菌氧化的影响因素

为确定巴彦乌拉铀矿酸法地浸构建细菌氧化工艺体系的可行性，探讨了细菌接种率、酸度、温度、亚铁浓度及过氧化氢投加量对细菌氧化亚铁的影响。结果表明：内蒙古巴彦乌拉铀矿吸附尾液接种细菌后有稳定亚铁氧化效果；外加硫酸至pH为0.6时，细菌仍能保持稳定活性；细菌对温度变化有较强的适应能力；初始亚铁浓度在0.35~4.81 g/L，随着亚铁浓度升高，细菌亚铁氧化速率逐渐上升；在生产中，细菌亚铁氧化体系需要有足够的通气量，可投加低浓度过氧化氢作为细菌氧化的辅助途径。     

充气量和补铁对嗜酸菌群铁氧化速率的影响

研究了充气量和补加铁对嗜酸菌群铁氧化速率的影响。结果表明,充气量低时菌群生长缓慢,提高充气量可促进菌群的生长和膜的形成,充气量过大则不利于细菌挂膜,影响菌群密度。5L培养体系的最佳充气量为0.6L/min。较大充气量可维持较高浓度的溶解氧及其平衡,获得较高的铁氧化速率。补加Fe2+可使菌群的生长维持在对数增长期及稳定期,可显著提高菌密度和铁氧化速率,铁氧化速率最高可达1.75g/(L.h),是常规菌液培养条件下的10倍左右。     

响应曲面法优化氧化亚铁硫杆菌氧化Fe2+工艺条件试验研究

在单因素试验基础上,研究了响应曲面法优化氧化亚铁硫杆菌氧化Fe2+的工艺条件。结果表明,初始ρ(Fe2+)、初始pH值、培养温度、接种量与响应值Fe2+氧化速率有显著相关性。典型性分析得到氧化亚铁硫杆菌氧化Fe2+的最佳工艺条件为:初始ρ(Fe2+)为8.44 g/L,溶液初始pH值为2.1,培养温度为33℃,接种量为12%。在此条件下,Fe2+氧化速率理论值达到0.217 g/(L.h),验证试验条件下实际最大氧化速率为0.215 g/(L.h)。     

氧化亚铁硫杆菌的固定化及动力学研究

以沸石为填料用吸附法构建了氧化亚铁硫杆菌固定化细胞生物反应器，考查了空气流量、液体流量对固定化效果的影响。在温度相同，培养基的pH=1．6，Fe^2＋浓度为8g／L左右的条件下，固定化细胞在Fe^2＋氧化率达95．36％时的氧化速率高达1．10/L·h，其Fe^2＋的氧化速率将近是游离细胞的18倍。固定化细胞生物反应器的动力学研究表明，氧化亚铁硫杆菌固定化细胞氧化Fe^2＋反应符合一级反应，其反应速率常数k为0．37h^-1。     

时效处理工艺对海工用高氮不锈钢耐蚀性的影响

海工用不锈钢需要长时间浸泡在海水当中，而海水自身是一种良好的电解质，具有含盐量高、电阻率小等特点，对不锈钢的耐腐蚀性是一种较大的考验。主要以18Cr15.5Mn1.4MoN系高氮奥氏体不锈钢为研究对象，通过固溶后的时效处理，分析时效第二相析出行为对试验钢耐蚀性能的影响。对试验钢进行盐雾腐蚀试验，计算其失重率和腐蚀速率，并测定试验钢动电位极化曲线。试验结果表明，不同时效处理后的试验钢耐蚀性能差距较大，600℃时效0.5 h试验钢耐蚀性能最佳，失重率和腐蚀速率分别为1.157%、4.608×10^-5 g/(cm²·h);800℃时效2 h耐蚀性能最差，失重率和腐蚀速率分别为3.737%、1.502×10^-4 g/(cm²·h);而316L不锈钢耐蚀性能介于两者之间，失重率和腐蚀速率分别为1.423%、6.751×10^-5 g/(cm²·h);当第二相Cr₂N大量析出时，会严重降低试样钢耐蚀性能。通过观察海工用高氮不锈钢第二相析出和溶解行为...     

氯离子对氧化亚铁硫杆菌和氧化亚铁钩端微螺菌活性的影响

采用连续稀释法分别从江西和广东某铀矿生物冶金现场筛选得到两株亚铁氧化菌。16srDNA鉴定结果表明,细菌分别为氧化亚铁硫杆菌(Acidimicrobium ferrooxidans)和氧化亚铁钩端微螺菌(Leptospirillum ferriphilum)。在氯离子浓度在1g/L以内,对细菌亚铁氧化活性基本没有影响;1~2g/L铁氧化活性有所降低,但是细菌通过调节依然能够适应并维持比较高的活性;氯离子浓度大于2g/L后亚铁氧化活性急速下降,当氯离子浓度大于3g/L后细菌生长受到抑制,亚铁氧化活性很低。     

新型奥氏体耐热钢NH4的高温氧化性能研究

通过增重法研究了新型奥氏体耐热钢NH4在700、900℃和1 000℃空气中的抗高温氧化性能。结果表明,NH4钢在700、900℃和1 000℃时的平均氧化速率分别为:0.064 g/(m2.h)、0.083 g/(m2.h)和0.278 6g/(m2.h)。在700℃和900℃时的氧化层是由外层的Cr2O3和内层的SiO2、Al2O3组成,在1 000℃时是由Cr、Si和Al 3种元素的混合氧化物组成。     

复杂微生物浸出液生物成矾法净化除铁的研究

针对低品位矿石生物浸出液中铁含量高而有价金属含量低的特点,研究低温、低pH条件下微生物成矾除铁方法,考察了温度、pH值、菌液接种量、时间等主要因素对微生物氧化及铁矾形成的影响规律,并采用正交实验对微生物成矾除铁规律进行多因素影响分析。结果表明:在生物氧化过程中,亚铁含量为9.46 g·L-1的料液,在pH范围为1.4～2.0,温度范围为30～40℃时,36 h细菌将亚铁氧化完全,细菌氧化亚铁的效果较好;在生物成矾除铁过程中,当pH为2,温度为45℃,菌液接种量为15%,反应时间为10 d时,除铁率达到99.97%,除铁后料液含铁0.015 g·L-1;通过正交实验,确定了影响生物成矾法除铁的主次因素顺序分别为反应时间、接种量、总铁浓度,最优水平组合为:总铁浓度50 g·L-1,接种量20%,反应时间10 d,在此最优组合条件下,沉淀除铁率高达99.95%,实现了低温、低pH条件下微生物成矾除铁,为微生物浸出液的低成本、高效净化除铁提供了一条新途径。     

Modeling Biooxidation of Iron in Packed-Bed Reactor

A model based on Monod kinetics and originally developed for use with rotating biological contactors was modified for use with a packed-bed column reactor. The reactor was filled with expanded polystyrene beads to immobilize chemolithotrophic bacteria and fed up to 570 mg L?1 (～10 mM) ferrous iron [Fe(II)] in simulated acid mine drainage. A tracer study indicated changing behavior as a function of hydraulic residence time (HRT), with a transition from complete mix flow behavior to plug flow behavior as HRT decreased. The Fe(II) oxidation efficiency exceeded 95% until the HRT was reduced below 0.5 h. The reactor performance could be predicted with the model using estimates from the literature for ? and Y. The experimentally determined half-saturation constant Ks was found to range from 5 to 12 mg L?1. The maximum volumetric capacity constant Rmax was estimated to be ～360 mg Fe(II)h?1 L?1 beads under complete mix flow conditions but appeared to be as high as 724 mg Fe(II)h?1 L?1 beads as conditions approached plug flow at short HRTs.     

One-Step Ambient Temperature Ferrite Process for Treatment of Acid Mine Drainage Waters

A novel approach toward the removal of iron and nonferrous metals from typical South African acid mine drainage (AMD) waters was investigated. The approach involves the controlled oxidation of ferrous-containing AMD water at ambient temperatures in the presence of magnetite seed. The resulting oxidation product is the ferrite (M123+M22+O4) magnetite (Fe3O4) which has the capacity for nonferrous metal removal by cation substitution. M?ssbauer spectroscopy, x-ray diffraction, and scanning electron microscopy analyses confirmed the precipitant to be magnetite. The effects of four parameters are reported: airflow rate, seed concentration, pH, and temperature. All of these independently affect the % ferrous in the final precipitant. In all experiments, the airflow rate was found to be rate limiting with respect to the kinetics of ferrous removal. The retention time for the complete removal of 1,200 mg Fe/L was 0.3–1.6 h (corresponding to airflow rates of 0.05–0.6 L/min, respectively). The precipitant settled well and showed complete stability at pH 5. The total iron concentration in the raw effluent was always less than 1 mg/L, representing an iron removal efficiency of greater than 99.9%.     

煤矸石化学氧化产酸产碱动力学定量描述

采用静态模拟试验方法,从含硫量不同的煤矸石的理化性质分析了煤矸石自身氧化产酸产碱规律。煤矸石氧化产酸是一个产酸产碱并存的过程,产酸过程主要是由硫化矿物的化学氧化控制,产碱过程则是碱性矿物溶解造成的酸度中和以及发生在某些硅酸盐矿物表面的因离子溶出而发生的质子交换。煤矸石的产酸阶段可以分为快速产酸期和稳定产酸期,产碱阶段可以分为快速产碱期和慢速产碱期。试样1煤矸石体系0~48 h为快速产酸期,产酸速率1.889 mmol/(kg?h),此后进入稳定产酸期,稳定产酸速率为0.012 mmol/(kg?h);0~24 h为快速产碱期,产碱速率1.594 mmol/(kg?h),之后产碱速率降为0.013 mmol/(kg?h)。试样2煤矸石体系的产酸产碱过程以48小时为转换点,快速产酸速率为0.243 mmol/(kg?h),稳定产酸速率为0.008 mmol/(kg?h);快速产碱速率为1.008 mmol/(kg?h),慢速产碱速率为0.033 mmol/(kg?h)。     

Fenton and Electro-Fenton Methods for Oxidation of H-Acid and Reactive Black 5

Oxidative treatment of H-acid (HA) and Reactive Black 5 (RB5) using Fenton reagent (Fe2+/H2O2) and the electro-Fenton (EF) method is reported. Optimization of doses of ferrous iron and hydrogen peroxide was carried out in each case using HA; and the oxidation of RB5 was also carried out under the optimized conditions. Approximately 71% chemical oxygen demand (COD) was removed in 2 h using the conventional Fenton method at optimized doses: Fe2+ = 0.3?g/L (5.37 mM), H2O2 = 6?mL/L (53.0 mM), H2O2/Fe2+ = 10. In contrast, more than 92% COD was removed in 15 min using the EF method with an optimized Fe2+ dose of 0.130?g/L (2.34 mM) and 8?ml/L (70.6 mM) of H2O2. The pseudo-first-order rate constants (k) for the Fenton reagent and EF method were 0.054 and 0.38?min?1. The COD removal through the EF method was seven times faster. The calculated energy requirement of the EF method was 0.82?kg?COD/kW?h at the minimum applied current (0.25 A) when approximately 92.5% COD was removed. In the case of RB5, about 67 and 87% COD was removed under optimized Fenton and electro-Fenton conditions, respectively. The higher efficiency of the EF method was attributed to incremental addition of Fe2+ and accompanying higher H2O2/Fe2+ molar ratio. The results are discussed in the light of the mechanism for Fenton’s oxidation.     

Novel atmospheric scorodite synthesis by oxidation of ferrous sulfate solution. Part I

A new atmospheric scorodite synthesis process was investigated. A large size and good crystalline scorodite was precipitated at 95 °C even in a short time of 1 to 7 h when ferrous ions were oxidized by oxygen gas in the presence of As(V) ion with concentrations as high as 50 g/L As in sulfuric acid solution. The key point of the process is the ferrous state of iron in solution and the oxidation of ferrous ions during the scorodite precipitation. This scorodite has a particle size of 15 μm with approximately 10% moisture content (wet base) even under atmospheric conditions. The arsenic content was about 30% by mass. The results of the leach test are very desirable. The process can be applied to a primary smelter which produces copper, zinc, lead and other secondary materials.     

永平铜矿浸矿细菌最佳生长条件的研究

对从永平铜矿酸性矿坑水中分离出的浸矿细菌进行了最佳生长条件的研究。结果表明,在9K+S培养基中,接种量为20%,pH为1 80,Fe2+浓度为3g/L,总铁为4g/L的条件下,既有利于细菌的生长,又有利于减少铁的沉淀,同时有利于矿物的浸出。