混合酸浸出废脱硝催化剂中钒的动力学研究

钒钛系脱硝催化剂由于长期运行在火电厂高温烟气中,活性会随着运行时间的延长而逐渐下降,使用寿命一般为3~4 a。其中约60%的脱硝催化剂受物理结构破损、机械性能下降等因素影响而不具备再生价值,需作报废处理。对其中有价金属元素的提取是实现报废脱硝催化剂高效资源化利用的重要方式。本文针对无机与有机混合酸溶液回收废脱硝催化剂中钒的过程,分析了浸出过程中的动力学模型,采用宏观动力学的研究方法,探究了浸出过程的控制类型。结果显示,硫酸-草酸混酸浸出废脱硝催化剂中钒的过程为典型的液-固相非催化反应类型,动力学模型为未反应核缩减模型。浸出过程中钒的动力学控制类型为表面化学反应控制,可用动力学方程来拟合,拟合直线的线性相关系数大于0.98,具有很好的线性相关性,该过程的反应活化能为4.53 kJ/mol。

非共沸烃／醇型混合溶剂浸出大豆的研究Ⅰ．最佳浸出工艺条件的选择

通过实验研究证明，由现行浸出溶剂与浓度为９１．１％ｗｔ的乙醇，按照一定配比构成的非共沸烃／醇型混合溶剂，对大豆具有良好的油脂浸出能力，可以作为现行浸出溶剂的替代溶剂在现行的浸出条件下使用。混合溶剂的组成在己烷：乙醇溶液＝７：３—５：５（重量比）的范围内是合适的，以６：４为最佳。按最佳配比构成的混合溶剂在浸出温度为５５℃，浸出时间为１００ｍｉｎ的条件下浸出大豆，可使残油率降至０．６９％，其浸出效果优于现行浸出溶剂。

非共沸烃／醇型混合溶剂浸出大豆的研究──Ⅱ．各浸出产物间的物料分配与产品分析

通过实验研究证明，非共沸烃／醇型混合溶剂［己烷：９１．１％乙醇＝６：４（重量比）］用于大豆的浸出，其湿粕含溶（３２％左右）、油相的混合油浓度（２５％左右）等工艺参数均与我国目前油脂行业现行的工艺要求基本吻合，能够为工业企业所接受。采用混合溶剂浸出技术得到的豆油达到国家二级豆油的标准，大豆蛋白具有良好的感观品质、较高的蛋白含量（５８．４２％）和优良的功能特性，有些指标达到大豆浓缩蛋白的水平，有可能作为大豆浓缩蛋白的替代产品直接用于火腿肠、冰淇淋等食品工业领域。

浸出混合油脱溶工艺对米糠毛油吸附脱色效果的影响

膨化米糠经浸出取油后所得混合油需要经过蒸发和汽提脱除溶剂才能得到浸出毛油。本试验分别采用常压蒸发、负压蒸发、分子蒸馏进行米糠混合油脱溶,分析研究不同脱溶条件对米糠毛油色泽及吸附脱色效果的影响。结果表明,三种脱溶工艺所得米糠浸出毛油的色泽有明显差异,常压蒸发所得毛油的色泽最深,其次是负压蒸发,分子蒸馏所得毛油的色泽最浅(罗维朋25.4 mm槽测定,Y值35时,3种毛油的R值分别为14.3、9.0和6.4,B值分别为9.0、4.1和4.0)。3种毛油的吸附脱色效果也有很大差别,活性白土用量由4%增加至12%时,常压蒸发毛油的脱色率从26.61%升高至46.42%,负压蒸发毛油和分子蒸馏毛油的脱色率分别由31.54%和32.93%升高至65.71%和66.85%。由此可知,混合油脱溶工艺和脱溶条件对米糠毛油色泽和吸附脱色效果有很大影响,混合油脱溶过程的高温作用会造成米糠毛油色泽的明显加深并形成固定色素使脱色难度增大。

丙酮-正己烷混合溶剂浸出棉籽

用正己烷-丙酮混合溶剂对棉籽坯片进行浸出，丙酮的浓度在10％～75％变化。正己烷中添加少量的丙酮溶剂即可以显著增加棉籽坯片中游离棉酚和总棉酚的萃取率。感官测试发现，用100％正己烷浸出的棉籽粕和体积比为90：10的正己烷一丙酮混合溶剂浸出的棉籽粕的气味没有差异。100％正己烷浸出棉籽坯片可以脱除约47％的游离棉酚，而正己烷一丙酮（90：10，V／V）混合溶剂可脱除超过80％的游离棉酚。

浸出混合油的预处理

我厂改建的,日处理80吨/饼油脂浸出车间于1976年投产。在工艺和设备上,我们集国内同行各家之长,还较注重了浸出混合油中的杂质控制。混合油中杂质含量多少,往往被一些浸出油厂所忽视。混合油中含杂质多。

废弃钴钼加氢催化剂碱性浸出规律研究

采用氨水和碳酸铵两种弱碱性试剂浸出处理废弃钴钼加氢催化剂,研究了影响金属元素Mo和Co浸出的因素。结果表明,单一浸出剂处理催化剂过程中会伴随Al的浸出,影响浸出液后续纯化处理,而复合浸出剂能有效抑制Al的浸出,可以直接进行浓缩回用。在氨水浓度为8.0 mol/L,碳酸铵浓度为0.5 mol/L,温度为70℃,固液比1:25的条件下连续浸出3次,Mo的浸出率达到90.21%,Co的浸出率达到69.22%。采用复合碱性浸出剂实现废弃加氢催化剂中钴钼元素回收,浸出剂可循环利用,效果良好。

植物油浸出技术最新发展与应用

通过介绍国内外植物油浸出最新技术,分析了这些技术运用的可行性及技术难度,比较这类技术在生产实践中产生的效益及技术的优越性,展望未来油脂浸出技术的发展。

微生物浸出砷黄铁矿基础研究和工业应用进展

概括了浸矿细菌的选择、驯化研究状况及氧化浸出砷黄铁矿机制和氧化过程中砷的转化形式,总结了单一菌种和混合菌种浸出砷黄铁矿的研究进展,以及工业浸出过程中存在的问题和解决方案,展望了砷黄铁矿细菌浸出研究和发展趋势。

浸出矿浆双氧水氧化除铁实验研究

针对采用焙砂(尘)-氧硫混合矿联合浸出工艺,在联合浸出段采用锰粉氧化-中和除铁中锰粉用量大导致电解液中Mn2+含量过高的问题开展双氧水氧化除铁实验研究。研究了终点pH值、温度、双氧水加入量以及时间等影响因素,结果表明:温度60℃,终点pH值控制在5.0左右,反应时间20 min,双氧水加入量为理论加入量的1.2倍时,除铁率可以达到99.55%。

湿法冶锌新浸取技术及其进展

本文概述了锌精矿湿法冶炼的多种新浸取工艺 ,进行相关综合评述 ,并介绍国内外一些湿法冶锌工艺发展新趋势。

天然法生产二硫化钼的改进工艺研究

对天然法生产二硫化钼的工艺进行了研究 ,提出了以分段浸出代替混合浸出的方案 ,并进行了实践。结果表明 ,二硫化钼的纯度可得到保证 ,而且有价元素可得到回收 ,生产过程中产生的废水经简单处理后可达标排放。

High efficient mixed culture screening and selected microbial community shift for bioleaching process

To screen the high efficient mixed culture and understand the bioleaching behaviors of mixed culture for low-grade copper sulfide ore bioleaching,ten mixed cultures were collected and screened from different acid mine drainages obtained from sulfide mines of China.The leaching rate was set as criterion to screen the mixed culture and the metagenomic approach.Community genome array（CGA） was used for analyzing the mixed culture microbial community shift during the bioleaching process.The results indicate that the mixed culture obtained from Yinshan（YS） lead-zinc mine in Dexing of Jiangxi province in China reaches the maximum copper extraction（68.89%） during the one bioleaching period of 24 d.CGA results show that YS culture contains nine kinds of bacteria which are belong to six divisions,and the microbial community structure is changing during the bioleaching process.This provides a good way to accelerate the bioleaching process and reveals the microbial community shift during the bioleaching process.

Extraction of germanium(IV) from acid leaching solution with mixtures of P204 and TBP

Solvent extraction experiments were conducted from acidic solutions containing germanium（IV） and other metal ions, such as Ga3＋, Fe3＋, Zn2＋ and Fe2＋ in hydrometallurgical process of zinc. The purpose of this work was to enhance the efficiency of the extraction and stripping processes and the selectivity of germanium and other metals, while making the method as simple as possible. Germanium was recovered from sulfuric acid, using di-（2-ethylhexyl） phosphoric acid （P2O4） as an extractant, tributyl phosphate （TBP） as modifier diluted in sulfonate kerosene and stripped by NaOH aqueous solution. Extraction studies were carried out under different acid concentrations and solvent concentrations, and optimized conditions were determined. The numbers of stages required for extraction and stripping of metal ions were determined from the McCabe-Thiele plot. The results show that the extracting and stripping efficiencies are 94.3% and 100%, respectively, through two-stage extraction and two-stage strip. Moreover, the synergistic effect of TBP on the system P2O4/kerosense/Ge4＋ is revealed with respect to the extraction of germanium.

Bioleaching and electrochemical properties of chalcopyrite by pure and mixed culture of Leptospirillum ferriphilum and Acidthiobacillus thiooxidans

The bioleaching of chalcopyrite was investigated using a pure and mixed culture consisting of iron-oxidizing Leptospirillum ferriphilum （L. ferriphilum） and sulfur-oxidizing Acidthiobacillus thiooxidans （.4. thiooxidans）. The electrochemical tests were conducted to investigate the bioleaching behavior of chalcopyrite by various bacteria. Bioleaching efficiency of chalcopyrite in mixed culture is higher than that in the pure culture of L.ferriphilum alone. The iron-oxidizing L.ferriphilum plays a dominant role during bioleaching of chalcopyrite in the mixed culture of L. ferriphilum and A. thiooxidans. During bioleaching, certain values of redox potential are beneficial to the decomposition of chalcopyrite. Jarosite and sulfur are observed as products of bioleaching. The addition of A. thiooxidans during leaching by L. ferriphilum can change the electrochemical control steps of leaching. The corrosion current density is substantially promoted in the culture involving bacteria, especially in the mixed culture.

Comparison of leaching of bornite from different regions mediated by mixed moderately thermophilic bacteria

Bioleaching experiments combined with X-ray photoelectron spectroscopy(XPS),X-ray diffraction(XRD)and scanning electron microscopy(SEM)were conducted to investigate three kinds of bornites from different regions leached by moderately thermophilic mixed bacteria of Leptospirillum ferriphilum YSK,Acidithiobacillus caldus D1 and Sulfobacillus thermosulfidooxidans ST.The results of bioleaching experiments showed that the leaching efficiency and the redox potential were significantly increased.The copper extraction efficiencies of three kinds of bornite maintained rapid growth until around the 12th day and no longer increased after the 18th,reaching 83.7%,96.5%and 86.6%,respectively.The XRD results of the leaching residue indicated that three kinds of bornites all produced jarosite in the late stage of leaching,and the leaching residues from of Daye Museum and Yunnan Geological Museum contained a mass of elemental sulfur.XPS analysis and scanning electron microscopy experiments showed that the surface of mineral particles was jarosite and the copper in the leaching residue was almost dissolved.

Comparison of bioleaching of chalcopyrite concentrates with mixed culture after cryopreservation with PEG-2000 in liquid nitrogen

A mixed culture of bioleaching microorganisms was enriched.Then the mixed culture was preserved by liquid nitrogen cryopreservation for 6 months and 12 months,respectively,using PEG-2000 as the protective agent.The chalcopyrite leaching ability,activity and diversity of the mixed culture before and after preservation were compared.The results showed that the copper extraction rate was 95.7%in chalcopyrite bioleaching within 20 d by the original culture.After cryopreservation for 6 months and 12 months,the copper extraction rate of the mixed culture was 94.9%within 25 d and 93.6%within 35 d,respectively.The cell viability achieved 87%and 41%after being preserved for 6 months and 12 months,respectively.Furthermore,the ecology analysis identified Acidithiobacillus ferrooxidans,Acidithiobacillus caldus,Sulfobacillus thermotolerans and Pseudomonas aeruginosa in the original mixed culture.After cryopreservation for 12 months,the composition of community changed,but the predominant microorganisms still existed.

Comparative study on chalcopyrite bioleaching with assistance of different carbon materials by mixed moderate thermophiles

The catalysis of four carbon materials including artificial graphite(AG), carbon black(CB), activated carbon(AC) and carbon nanotube(CN) on chalcopyrite bioleaching by mixed moderate thermophiles was comparatively investigated. In AC and AG added bioleaching groups, low solution pH and suitable redox potential values, high total iron and ferric iron concentrations, and large number of adsorbed bacteria were obtained, resulting in high copper extractions. CB and CN inhibited the growth of bioleaching bacteria and led to the low bioleaching efficiency.X-ray diffraction analysis showed that jarosite and sulfur film were the main components of passivation layer with the addition of AG and AC,but did not hinder the dissolution of chalcopyrite. Microbial community structures of free and attached cells in AC and AG added groups changed dramatically compared with mixed moderate thermophiles. The sulfur-oxidizing bacteria of A. caldus S1 strain dominated the microbial community(93%-98%) at the end of bioleaching.The iron-oxidizing bacteria of L.ferriphilum YSK only accounted for low percentage(1%-2%).

Bioleaching of complex polymetallic sulfide ores by mixed culture

Bacterial leaching of single sulfide minerals and polymetallic sulfide ores was operated in shake flasks and small-scaled columns.The results show that bioleaching of jamesonite is not accessible,the iron extraction rate of pyrrhotite bioleaching reaches 98.2% after 26 d,and the zinc extraction rate of marmatite bioleaching reaches 92.3%,while the corresponding iron extraction reaches only 13.6% after 29 d.Pulp density has a significant effect on metal extraction of pyrrhotite and marmatite bioleaching.The corresponding metal extraction rate decreases with the increase of pulp density.For the polymetallic sulfide ores,zinc extraction of 97.1% is achieved after bioleaching in shake flasks for 10 d,while only 7.8% is obtained after bioleaching in small-scaled column.Analytical results of scanning electron microscopy(SEM) and energy dispersive X-ray analysis(EDX) reveal that large amount of calcium sulfate is formed on the mineral surface.

Bioleaching of chalcocite by mixed microorganisms subjected to mutation

Mixed microorganisms with elevated activity of chalcocite-leaching were screened by mutation methods. The original microorganisms collected from acid mine drainage of different sites were mixed and then treated with mutagens NO2^- , diethyl sulfate （DES）, UV and their combinations, respectively. Five groups of mixed microorganisms with much stronger ore-leaching ability were obtained by screening on the leaching media. Among them, group E of mixed microorganisms （treated with 1% DES for 60 min） with the best perfonnance on chalcocite-leaching, increases the content of Cu^2＋ by 101.4% in 20 d of leaching compared with the control culture. In addition, group E is more tolerant to Cu^2＋ in media than the control without mutation treatment. Analysis for the diversity of microbial clones indicates that half of operational taxonomic units （OTUs） in group E are Acidithiobacillus ferrooxidans. These observations suggest that group E might have potentials for industrial application.