Oxidative leaching kinetics of molybdenum-uranium ore in H2SO4 using H2O2 as an oxidizing agent

The processing of molybdenum-uranium ore in a sulfuric acid solution using hydrogen peroxide as an oxidant has been investigated. The leaching temperature, hydrogen peroxide concentration, sulfuric acid concentration, leaching time, particle size, liquid-to-solid ratio and agitation speed all have significant effects on the process. The optimum process operating parameters were: temperature: 95°C; H₂O₂ concentration: 0.5 M; sulfuric acid concentration: 2.5 M; time: 2 h; particle size: 74 μm, liquid-to-solid ratio: 14 ∶ 1 and agitation speed: 600 rpm. Under these experimental conditions, the extraction efficiency of molybdenum was about 98.4%, and the uranium extraction efficiency was about 98.7%. The leaching kinetics of molybdenum showed that the reaction rate of the leaching process is controlled by the chemical reaction at the particle surface. The leaching process follows the kinetic model 1 ? (1?X)^1/3 = kt with an apparent activation energy of 40.40 kJ/mole. The temperature, concentrations of H₂O₂ and H₂SO₄ and the mesh size are the main factors that influence the leaching rate. The reaction order in H₂SO₄ was 1.0012 and in H₂O₂ it was 1.2544.     

富硼渣硫酸浸出实验研究

以硼铁精矿含碳球团还原熔分得到的富硼渣为原料,研究了其物相成分,并进行硫酸浸出实验,探究了硫酸用量、反应温度、反应时间及液固比对硼浸出率的影响。结果表明,该富硼渣中三氧化二硼的质量分数达到20%,主要含遂安石相和橄榄石相。硫酸浸出实验中,硼浸出率随着硫酸用量、反应温度和反应时间的增加而增大,随着液固比的增大而减小。当硫酸用量为理论用量的80%、液固体积质量比为8 mL/g、反应温度为40 ℃、反应时间为60 min时,富硼渣中硼的浸出率达到93.56%。     

富锰渣制备硫酸锰过程中除杂方法新探

研究了以富锰渣为原料,经硫酸浸出制备硫酸锰的工艺过程中除杂方法。分别探讨了以MnO2、H2O2、空气为氧化剂,以NH3.H2O、Ca(OH)2、富锰渣等为中和除杂剂,控制pH在5~6,中和除杂温度为50~60℃,保温时间1~1.5 h情况下,采用不同的除杂剂及除杂条件,取得了不同的除杂效果。     

硫酸-糖蜜酒精废液浸出软锰矿的动力学(英文)

The kinetics of reductive leaching of manganese from low grade pyrolusite in dilute sulfuric acid in the presence of molasses alcohol wastewater was investigated. The shrinking core model was applied to quantify the effects of reaction parameters on leaching rate. The leaching rate increases with reaction temperature, concentrations of H 2 SO 4 and organic matter in molasses alcohol wastewater increase and ore particle size decreases. The leaching process follows the kinetics of a shrinking core model and the apparent activation energy is 57.5 kJ·mol –1 . The experimental results indicate a reaction order of 0.52 for H2SO4 concentration and 0.90 for chemical oxygen demand (COD) of molasses alcohol wastewater. It is concluded that the reductive leaching of pyrolusite with molasses alcohol wastewater is controlled by the diffusion through the ash/inert layer composed of the associated minerals.     

Effects of mechanical activation on the digestion of ilmenite in dilute H2SO4

The commercial sulfate process for pigment production uses concentrated sulfuric acid(N 85 wt% H_2SO_4) as feeding material and discharges 8–10 tons of spend dilute acid(20 wt% H_2SO_4) per ton of product. Re-using spend acid to leach ilmenite can cut the waste emission and save fresh feeding acid. However, the leaching reaction with dilute acid is very slow and the digestion efficiency is fairly low. This paper describes a wet-milling process to enhance the dilute-acid leaching of ilmenite that makes it possible to produce TiO_2 pigment in a more environmentally benign routine. The leaching kinetic study of unmilled ilmenite, dry milled 60 min ilmenite and wet milled 60 min ilmenite was conducted by revision of the shrinking core model(SCM), incorporation of particle size distribution(PSD) into SCM. The results revealed that mechano-chemical activation method significantly increased the leaching efficiency of titanium from 36% to 76% by reducing the particle size and increasing the reaction contact area. On the other hand, the milling process increased the lattice deformation and amorphization of crystalline, which lowered the activation energies in the leaching process. Compared with dry milling operation, wet milling is more effective, the particle size distribution of wet-milled ilmenite was much narrower, smaller, and more uniform. Wet milling of ilmenite makes the leaching reaction with dilute acid(60 wt% H_2 SO_4) practicable and the re-use of spend acid becomes possible and economical.     

微生物浸出MnO2过程中嗜酸氧化亚铁硫杆菌与Fe3+的催化作用

考察了MnO₂-FeS₂-H₂SO₄细菌浸出体系下,嗜酸氧化亚铁硫杆菌和Fe³⁺单独或联合对MnO₂浸出Mn²⁺的浸出速率影响,并采用循环伏安电化学方法对过程中嗜酸氧化亚铁硫杆菌与Fe³⁺的催化作用进行了分析。结果表明：嗜酸氧化亚铁硫杆菌和Fe³⁺单独或联合都可以有效提高MnO₂浸出Mn²⁺的浸出速率,对MnO₂细菌浸出过程有一定催化作用;循环伏安电化学分析表明嗜酸氧化亚铁硫杆菌和Fe³⁺单独或联合加入,都会使FeS₂出现明显的氧化还原峰,且嗜酸氧化亚铁硫杆菌可以降低FeS₂的氧化电位和缩短FeS₂氧化峰与还原峰之间的电位差,从而催化MnO₂浸出Mn²⁺的过程。     

氢氧直接合成法制过氧化氢技术进展

氢气和氧气直接合成过氧化氢是典型的原子经济性反应，因过程简单、产品清洁、生产成本低而成为催化领域研究开发的一个热点。总结了该法近年来在催化剂活性组分的选取及载体方面的进展；详细介绍了溶剂的选取和反应机理；讨论了各种反应器的安全性。指出今后的研究重点是提高氢气利用率、开发新型的反应器、提高过程的安全性。     

氯化锂-乙醇-水溶液稀释热

使用 Ｌ Ｋ Ｂ ２１０７ 型流动式微量热计微机数据采集系统测量了 ２８８．１５ Ｋ、２９８．１５ Ｋ 和 ３０８１５ Ｋ 下 Ｌｉ Ｃｌ Ｃ２ Ｈ５ Ｏ Ｈ Ｈ２ Ｏ 体系在不同混合溶剂浓度下的稀释热。测量结果用扩展的 Ｄｅｂｙｅ Ｈüｃｋｅｌ方程、 Ｐｉｔｚｅｒ 模型和单参数模型关联。计算了方程的参数和溶液无限稀释热（ｍ Ｌｉ Ｃｌ＝ １．０ ｍ ｏｌ／ｋｇ 溶剂）－ Δ Ｈ Ｄ∞ 。结果表明：相同混合溶剂浓度下,－ Δ Ｈ Ｄ ∞ 随温度增加而增加;同一温度下,－ Δ Ｈ Ｄ∞ 与溶剂浓度有关,在 ｘ２ ＝ ０．８５ 左右,－ Δ Ｈ Ｄ∞ 具有最大值。     

Na2O—CaO—TiO2—P2O5系统多孔微晶玻璃的制备

自1934年，H·P·Hood等人发明了Vyocr glass 以来，用于制备多孔玻璃的基础玻     

柱淋滤模式下生活垃圾焚烧炉渣中Cu2+和Zn2+浸出规律

垃圾焚烧炉渣是一种活性材料,在其储存、预处理及应用等过程与雨水频繁接触时,炉渣中重金属随着水域环境发生迁移和浸出现象。本研究采用连续柱淋滤试验装置模拟自然降雨,开展了0～5mm和5～10mm焚烧炉渣的动态淋滤毒性浸出分析,重点研究了pH和降雨强度对Cu²⁺和Zn²⁺的浸出影响。结果表明,动态淋滤过程中,淋滤液pH变化对Cu²⁺和Zn²⁺的浸出水平影响显著,且在酸性较强淋滤液作用下Cu²⁺浸出水平比Zn²⁺更强,与Ⅴ类地表水环境浓度限值对比,在整个淋滤时间内Cu²⁺浸出浓度严重超标,在炉渣工程应用时需预防相关的环境风险;原生炉渣粒径大小与重金属浸出水平无直接相关性,但是0～5mm细炉渣中可浸出Zn²⁺含量更高,这与细颗粒物中Zn赋存形态和可溶出态含量较高有关;淋滤强度对重金属浸出水平影响主要反应了动态淋滤过程液固比和水分运移速率情况,当较低淋滤强度时具有低液固比,溶出液中重金属含量较高。     

提高CFB灰中铝的浸出率的研究

通过化学成分分析、XRD分析方法,对阜新金山CFB灰的性质进行了研究,该灰中主要结晶矿物为石英、长石、赤铁矿等,有少量玻璃体存在.通过改变浸出酸浓度、浸出温度和助浸剂的用量,确定了各因素对CFB灰中Al2O3浸出率的影响,使浸出率达到85％以上.达到试验研究目的.     

钒钛磁铁矿混合精矿在盐酸中Fe/V/Ti的浸出行为

以预还原处理后的钒钛磁铁矿混合精矿为原料,用盐酸浸出其中的铁、钒、钛,考察了各因素对铁、钒、钛浸出率的影响,并对浸出渣进行了物相分析. 结果表明,在初始盐酸浓度20%(?)、液固质量比4:1、浸出温度110℃、浸出时间4 h的优化浸出条件下,铁、钒的浸出率分别为91.8%和95.0%,钛的浸出率为0.3%;浸出过程中钛是先溶解?再水解沉淀;盐酸浸出液可用于回收铁和萃取提钒;盐酸浸出渣中TiO2的硫酸分解率达98.2%,可作为硫酸法生产钛白的原料.     

酸化—吹气分光光度法测定甲醇中的微量H2S

甲醇中微量Ｈ２Ｓ的测定通常采用微库仑定硫法,但实际使用过程中存在一些问题。经过大量的试验,证实了酸化－吹气分光光度法测定甲醇中的微量Ｈ２Ｓ能替代微库仑定硫法。     

CO_2-C_4H_9OH-H_2O体系的立方型状态方程研究

利用 Ｐ Ｒ、 Ｓ Ｒ Ｋ、 Ｈ Ｋ、 Ｐ Ｔ 状态方程（ Ｅ Ｏ Ｓ）计算 Ｃ Ｏ２ 、 Ｃ４ Ｈ９ Ｏ Ｈ、 Ｈ２ Ｏ 纯组份的饱和性质及 Ｃ Ｏ２ 的压缩因子。结果表明, Ｐ Ｔ 方程对水、二氧化碳的蒸汽压及密度预测较佳。对丁醇的密度推算, Ｐ Ｔ 方程最佳, Ｐ Ｔ 方程对丁醇的饱和蒸汽压预测一般。考察了 Ｐ Ｔ 方程参数的影响,指出应根据相平衡的温度范围选取相应的 Ｐ Ｔ 方程参数。对 Ｃ Ｏ２  Ｃ４ Ｈ９ Ｏ Ｈ Ｈ２ Ｏ 体系相平衡的研究宜选用 Ｐ Ｔ 方程。     

Ti-containing MCM-41 catalysts for liquid phase oxidation of cyclohexene with aqueous H2O2 and tert-butyl hydroperoxide

Framework Ti-substituted and Ti-grafted MCM-41 mesoporous material has been prepared by direct hydrothermal synthesis and a post-synthesis grafting method. The materials have been tested as catalysts for cyclohexene oxidation with aqueous H₂O₂ and tert-butyl hydroperoxide (TBHP). With aqueous H₂O₂ in methanol, the major products were cyclohexene diol and its methyl ethers. No cyclohexene oxide was produced. Titanium leaching was a serious problem, and the catalyst lost its activity irreversibly after only one cycle of reaction. With TBHP, the selectivity for cyclohexene oxide was near 100%, titanium leaching was negligible, and the catalyst could be repeatedly used after regeneration without suffering significant activity loss. However, the reaction rate was lower than when H₂O₂ was used. Framework substituted material and catalysts prepared by Ti-grafting onto a MCM-41 support behaved similar, but the Ti-grafted MCM-41 is somewhat more active. The turnover frequency (TOF) per mole of Ti decreases with an increase of Ti content in the catalyst. This is caused by a reduced Ti dispersion within the silica matrix. This revised version was published online in July 2006 with corrections to the Cover Date.     

中原大化50%过氧化氢装置的优化设计

对中原大化5kt/a 50％过氧化氢装置生产中存在的问题进行分析和研究,提出改造方案和改进设想,为同类厂家和科研单位提供参考和借鉴。     

Direct Oxidation of H2 to H2O2 and Decomposition of H2O2 Over Oxidized and Reduced Pd-Containing Zeolite Catalysts in Acidic Medium

Both the conversion and H₂O₂ selectivity (or yield) in direct oxidation of H₂-to-H₂O₂ (using 1.7 mol% H₂ in O₂ as a feed) and also the H₂O₂ decomposition over zeolite (viz. H-ZSM-5, H-GaAlMFI and H- ) supported palladium catalysts (at 22 °C and atmospheric pressure) are strongly influenced by the zeolite support and its fluorination, the reaction medium (viz. pure water, 0.016 M or 1.0 M NaCl solution or 0.016 M H₂SO₄, HCl, HNO₃, H₃PO₄ and HClO₄), and also by the form of palladium (Pd⁰ or PdO). The oxidized (PdO-containing) catalysts are active for the H₂-to-H₂O₂ conversion and show very poor activity for the H₂O₂ decomposition. However, the reduced (Pd⁰-containing) catalysts show higher H₂ conversion activity but with no selectivity for H₂O₂, and also show much higher H₂O₂ decomposition activity. No direct correlation is observed between the H₂-to-H₂O₂ conversion activity (or H₂O₂ selectivity) and the Pd dispersion or surface acidity of the catalysts. Higher H₂O₂ yield and lower H₂O₂ decomposition activity are, however, obtained when the non-acidic reaction medium (water with or without NaCl) is replaced by the acidic one.     

十水合硫酸钠及十水合碳酸钠热导率的测量研究

用热敏电阻作加热元件和测温元件,首次系统测定了适合用作相变储热材料的十水合硫酸钠、十水合碳酸钠在温度范围10～80℃的热导率,两者实验热导率的偏差率分别为:±2.56%和±2.41%。同时,报道了十水合硫酸钠、十水合碳酸钠在实验中观测到的熔点分别为30℃和30℃,这些测量值与文献值基本吻合。     

A H2S-Specific Ultrasensitive Fluorogenic Probe Reveals TMV-Induced H2S Production to Limit Virus Replication

Understanding the role of H₂S in host defense mechanisms against RNA viruses may provide opportunities for the development of antivirals to combat viral infections. Here, we have developed a green-emitting fluorogenic probe, which exhibits a large fluorescence response at 520 nm (>560-fold) when treated with 100 μM H₂S for 1 h. It is highly selective for H₂S over biothiols (>400-fold F/F₀) and has a detection limit of 12.9 nM. We demonstrate the application of the probe for endogenous H₂S detection in vivo for the understanding of its roles in antiviral host defense. Such virus-induced H₂S inhibits viral replication by reducing gene expression of RNA-dependent RNA polymerase (RdRp) and coat protein (CP). Additionally, a H₂S donor GYY4137 showed significantly antiviral activity as ribavirin, a broad-spectrum drug against RNA viruses. Furtherly, we propose a possible molecular mechanism for the TMV-induced H₂S biogenesis. This work provides a proof-of-principle in support of further studies identifying endogenous H₂S and its donors as potential antivirals toward RNA viruses.     

FeOOH/H_2O_2催化降解碱性品红的研究

采用FeOOH/H2O2体系对一种碱性阳离子染料进行催化降解。考察了H2O2浓度、FeOOH的投加量、碱性品红的浓度、pH对碱性品红降解的影响。结果表明,反应的较优条件是H2O2浓度为60 mmol/L,FeOOH投加量1.0 g/L;碱性品红浓度高的降解速率比较慢,浓度低的降解速率快;pH=1时,碱性品红去除率为90.9%;pH=9时,碱性品红去除率为98.9%。机理研究表明,当溶液pH小于FeOOH的零电荷点时,FeOOH表面带正电荷,与带正电荷的碱性品红之间相互排斥降低了对碱性品红的吸附作用,同时部分Fe离子发生溶解,溶解的铁离子与H2O2形成Fenton体系;当溶液pH大于FeOOH的零电荷点时,FeOOH带负电荷,碱性品红因静电力被吸附在FeOOH表面,同时与产生的羟基自由基发生反应。