用草酸在硫酸溶液中从中性浸出渣中还原浸出铟

The present study evaluates the reductive leaching of indium from indium-bearing zinc ferrite using oxalic acid as a reducer in sulfuric acid solution. The effect of main factors affecting the process rate, including the oxalic-acid-to-sulfuric-acid ratio, stirring rate, grain size, temperature, and the initial concentration of synergic acid, was precisely evaluated. The results confirmed the acceptable efficiency of dissolving indium in the presence of oxalic acid. The shrinking-core model with a chemical-reaction-controlled step can correctly describe the kinetics of indium dissolution. On the basis of an apparent activation energy of 44.55 kJ/mol and a reaction order with respect to the acid concentration of 1.14, the presence of oxalic acid was found to reduce the sensitivity to temperature changes and to increase the effect of changes in acid concentration. Finally, the equation of the kinetic model based on the factors under study is presented.     

氯气氧化分解草酸钴沉淀母液中的草酸

为有效去除草酸沉钴母液中残留的大量草酸,采用氯气作为氧化剂探索氧化分解母液中草酸的可行性。考察反应温度、反应时间、氯气用量、搅拌速度和钴离子浓度等因素对氧化效果的影响。确定了优化工艺条件:反应温度50℃,搅拌速度700 r/min,次氯酸钙150 g,6 mol/L盐酸550 mL,反应时间3 h。在此条件下,草酸的氧化率可达97.9%,母液中残留的草酸质量浓度仅为0.42 g/L,处理后的母液可直接返回含钴物料的浸出,实现了工艺流程的闭路循环。     

Sulfuric acid leaching of high iron-bearing zinc calcine

Sulfuric acid leaching of high iron-bearing zinc calcine was investigated to assess the effects of sulfuric acid concentration, liquid-to-solid ratio, leaching time, leaching temperature, and the stirring speed on the leaching rates of zinc and iron. The results showed that the sulfuric acid concentration, liquid-to-solid ratio, leaching time, and leaching temperature strongly influenced the leaching of zinc and iron, whereas stirring speed had little influence. Zinc was mainly leached and the leaching rate of iron was low when the sulfuric acid concentration was less than 100 g/L. At sulfuric acid concentrations higher than 100 g/L, the leaching rate of iron increased quickly with increasing sulfuric acid concentration. This behavior is attributed to iron-bearing minerals such as zinc ferrite in zinc calcine dissolving at high temperatures and high sulfuric acid concentrations but not at low temperatures and low sulfuric acid concentrations.     

草酸溶蚀白云石规律探究

为更好的探究白云石与地层酸性流体的溶蚀作用规律,为后续研究白云岩储层的油气储集提供积极的指导作用。本文开展了白云石与草酸的溶蚀模拟实验,主要考查了反应温度、草酸浓度及矿化度对草酸溶蚀白云石过程的影响。结果表明：反应温度增大不仅能提高反应速率,而且影响溶液中镁离子溶出浓度。草酸浓度较高时,溶液中镁离子溶出浓度不随草酸浓度升高而增大。且反应产物均沉淀在白云石表面上,阻止了内部溶蚀反应的进行,不利于孔隙优质储层的形成。草酸溶液中氯化钠的加入一方面有利于速率的提高及白云石的溶解度的增加,另一方面抑制了溶液中镁离子的沉淀     

Influence of acid leaching and calcination on iron removal of coal kaolin

Calcination and acid leaching of coal kaolin were studied to determine an effective and economical preparation method of calcined kaolin. Thermogravimetric-differential thermal analysis (TG-DTA) and X-ray diffraction (XRD) demonstrated that 900℃ was the suitable temperature for the calcination. Leaching tests showed that hydrochloric acid was more effective for iron dissolution from raw coal kaolin (RCK), whereas oxalic acid was more effective on iron dissolution from calcined coal kaolin (CCK). The iron dissolution from CCK was 28.78wt%, which is far less effective than the 54.86wt% of RCK under their respective optimal conditions. Through analysis by using M?ssbauer spectroscopy, it is detected that nearly all of the structural ferrous ions in RCK were removed by hydrochloric acid. However, iron sites in CCK changed slightly by oxalic acid leaching because nearly all ferrous ions were transformed into ferric species after firing at 900℃. It can be concluded that it is difficult to remove the structural ferric ions and ferric oxides evolved from the structural ferrous ions. Thus, iron removal by acids should be conducted prior to calcination.     

高铟闪锌矿在氧压酸浸中铟浸出动力学的研究

铟是一种重要的多用途战略金属,具有较高的工业应用价值,但无独立可供开采的矿床,常伴生于铅锌等硫化矿中.因此,本文在传统电加热条件下进行了高铟闪锌矿氧压酸浸过程中铟浸出动力学实验的研究.结果表明:采用“有固态产物层的液-固相浸出反应动力学模型”对铟浸出动力学进行了研究,可知其浸出速率受到界面化学反应控制,其表观活化能为69.735kJ/mol,以及高铟闪锌矿氧压酸浸过程中铟浸出率随粒度减小、初始酸度增大、氧分压增大、浸出温度增大而增大.     

草酸联合东南景天修复镉污染土壤实验研究

为了解草酸淋洗联合东南景天修复镉污染土壤的效果,选取矿山生态型东南景天根系分泌物中的草酸作为淋洗剂,联合矿山生态型东南景天进行镉污染土壤修复的实验.通过4种浓度的草酸分别对土壤进行了4次淋洗后,可以看出草酸浓度达到25 mmol/L时,东南景天干重最大,地上部镉含量最多,总去除量最大,去除效率可以达到51.34%,与不淋洗组对比高35个百分点.实验表明草酸浓度在25 mmol/L时联合东南景天修复镉污染土壤的效果达到最佳.实验证明使用草酸淋洗联合矿山型东南景天修复镉污染土壤,镉的去除效果比较显著,且生态型东南景天生长健康,从而为草酸联合东南景天修复镉污染技术的推广和应用提供了科学依据.     

Preparation of manganese sulfate from low-grade manganese carbonate ores by sulfuric acid leaching

In this study, a method for preparing pure manganese sulfate from low-grade ores with a granule mean size of 0.47 mm by direct acid leaching was developed. The effects of the types of leaching agents, sulfuric acid concentration, reaction temperature, and agitation rate on the leaching efficiency of manganese were investigated. We observed that sulfuric acid used as a leaching agent provides a similar leaching efficiency of manganese and superior selectivity against calcium compared to hydrochloric acid. The optimal leaching conditions in sulfuric acid media were determined; under the optimal conditions, the leaching efficiencies of Mn and Ca were 92.42% and 9.61%, respectively. Moreover, the kinetics of manganese leaching indicated that the leaching follows the diffusion-controlled model with an apparent activation energy of 12.28 kJ·mol-1. The purification conditions of the leaching solution were also discussed. The results show that manganese dioxide is a suitable oxidant of ferrous ions and sodium dimethyldithiocarbamate is an effective precipitant of heavy metals. Finally, through chemical analysis and X-ray diffraction analysis, the obtained product was determined to contain 98% of MnSO₄·H₂O.     

硫酸中香蕉皮还原低品位锰矿的浸出行为及动力学模型

Manganese was leached from a low-grade manganese ore (LGMO) using banana peel as the reductant in a dilute sulfuric acid medium. The effects of banana peel amount, H₂SO₄ concentration, reaction temperature, and time on Mn leaching from the complex LGMO were studied. A leaching efficiency of ~98% was achieved at a leaching time of 2 h, banana peel amount of 4 g, leaching temperature of 120°C, manganese ore amount of 5 g, and sulfuric acid concentration of 15vol%. The phase, microstructural, and chemical analyses of LGMO samples before and after the leaching process confirmed the successful leaching of manganese. Furthermore, the leaching process followed the shrinking core model and the leaching rate was controlled by a surface chemical reaction (1 ? (1 ? x)1/3 = kt) mechanism with an apparent activation energy of 40.19 kJ·mol?1.     

规整填料塔吸收NOx过程的模拟和实验

为了解决工业中NOx污染问题，以双膜理论为基础建立并求解了氮氧化物在绝热情况下采用高效规整填料塔进行常压水吸收的数学模型，对NOx脱出率、出口含量、氧化度、出塔酸浓度及液体酸温度进行了模拟，同时进行了实验验证。模型涉及水吸收的气相反应及平衡、气相传质过程、界面平衡和液相反应。实验装置为已投产运行的年产2万吨草酸的吸收塔设备，模拟结果与工业实验装置现场采集的数据吻合较好，可以作为氯氧化物工业化生产的理论依据。     

三辛胺萃取草酸的溶剂再生研究

为探索有机酸反应萃取过程的溶剂再生及溶质净化的途径 ,选择 Na OH、 KOH及三甲胺 3种反萃剂 ,进行负载草酸有机溶剂再生特性的研究。测定了碱液浓度、相比、负载草酸初始浓度及反萃液中初始盐浓度等因素对草酸反萃过程的影响及循环反萃过程的可行性。据溶剂再生后草酸盐的性质 ,开展了双极性膜电渗析法、减压蒸发热解法实现草酸盐再生的可行性初探。     

Investigation on leaching of malachite by citric acid

Leaching of an oxidized copper ore containing malachite, as a new approach, was investigated by an organic reagent, citric acid. Sulfuric acid is the most common reagent in the leaching of oxide copper ores, but it has several side effects such as severe adverse impact on the environment. In this investigation, the effects of particle size, acid concentration, leaching time, solid/liquid ratio, temperature, and stirring speed were optimized. According to the experimental results, malachite leaching by citric acid was technically feasible. Optimum leaching conditions were found as follows:the range of particle size, 105-150 μm; acid concentration, 0.2 M; leaching time, 30 min; solid/liquid ratio, 1:20 g/mL; temperature, 40℃; and stirring speed, 200 r/min. Under the optimum conditions, 91.61% of copper was extracted.     

从废弃木屑中提取乙二酸方法的研究

从木屑中提取乙二酸成本低 ,工艺简单 ,可综合利用 ,变废为宝 .介绍了用浓碱处理木屑从木屑中提取乙二酸的方法 ,试验了碱液浓度及碱熔温度对产率的影响 ,并试验了乙二酸的漂白功能     

从废弃木屑中提取乙二酸方法的研究

从木屑中提取乙二酸成本低，工艺简单，可综合利用，变废为宝．介绍了用浓碱处理木屑从木屑中提取乙二酸的方法，试验了碱液浓度及碱熔温度对产率的影响，并试验了乙二酸的漂白功能．     

助熔剂辅助碱熔-酸浸法制备高纯石墨

针对石墨中含有可溶性硅酸盐的情况,采用助熔剂辅助碱熔-酸浸法将天然鳞片石墨提纯,研究助熔剂种类及其用量、氢氧化钠质量分数、焙烧熔融温度、焙烧熔融时间对石墨纯化效果的影响,并对样品进行扫描电子显微镜(SEM)和X射线衍射(XRD)表征。结果表明:以偏硼酸锂作为碱熔焙烧助熔剂的纯化效果最佳。取质量分数60%的氢氧化钠溶液10 mL、质量分数20%的盐酸溶液20 mL、偏硼酸锂0.6 g、石墨10 g,在焙烧温度500℃、焙烧时间120 min、酸浸温度80℃、酸浸时间80 min的条件下,石墨的固定碳w(C)可由87.62%提高到99.69%。SEM和XRD分析表明,助熔剂辅助碱熔-酸浸法石墨纯化技术没有破坏石墨本身的结构与形貌。该工艺方法简单,反应温度低,污染小,能耗较低,能显著提高石墨的固定碳,可用于指导高纯石墨的生产实践。     

Leaching kinetics of celestite in nitric acid solutions

In this study, strontium nitrate extraction from celestite in nitric acid solutions was investigated using the leaching method. The influences of acid concentration, solid-to-liquid ratio, stirring speed, and reaction temperature on the leaching of strontium from celestite concentrate were studied. The results showed that the leaching rate increased with increasing acid concentration, stirring speed, and temperature and decreased with increasing solid-to-liquid ratio. The particle size was fixed in all of the dissolution experiments. The results showed that the stirring speed and the temperature were the most influential parameters with respect to the leaching process. The kinetic model best fit control by diffusion through the product layer. The activation energy of the dissolution celestite in nitric acid solutions was calculated to be 42.22 kJ/mol.     

3种低分子质量有机酸对温带典型林型土壤无机磷组分的影响

【目的】为了使土壤中潜在的无机磷转化为可供植物吸收利用的有效磷,探讨3种低分子质量有机酸对温带典型林型土壤无机磷组分的影响,旨在为温带退化森林生态系统的恢复与重建,以及土壤磷利用率的提高提供基础数据和科学依据。【方法】笔者对温带典型林型土壤采用室内培养法培养120 d,研究了不同浓度(10、25、50 和100 mmol/L)草酸、柠檬酸和乙酸及其对照(CK,蒸馏水)对4种温带典型林型(枫桦红松混交林、白桦天然次生林、红松人工林和落叶松人工林)0～10 cm土层土壤无机磷(Al-P、Fe-P、O-P、Ca-P)含量的影响。【结果】3种低分子质量有机酸均对红松及落叶松人工林内Al-P、Fe-P起活化作用,对O-P、Ca-P起固化作用,3种酸的影响效果为草酸>柠檬酸>乙酸。柠檬酸、草酸使白桦天然次生林O-P含量减少,使其转化为其他形态无机磷。整体来说,低分子质量有机酸处理4种林型土壤后,无机磷向有效性高的Al-P、Fe-P形态转化,从而提高了土壤供磷能力。低分子质量有机酸对土壤无机磷组分变化影响显著(P<0.05),中低浓度有机酸对Al-P、Fe-P、O-P变化影响较大,高浓度有机酸对Ca-P变化影响明显。处理时间对无机磷变化量影响显著(P<0.05),处理时间延长整体使4种林型中Al-P、Fe-P受到的影响加强,O-P、Ca-P受到的影响减弱。各因素对4种林型有显著的交互作用(P<0.05)。土壤中无机磷组分含量变化与无机磷形态、有机酸的种类、培养时间、酸浓度变化及林型等因素均相关。【结论】有机酸对土壤磷的活化是一个既缓慢又持续的综合动态过程,低分子质量有机酸可以通过影响土壤中无机磷的组分,促进难溶性磷酸盐溶解,从而提高土壤磷的有效性。此次研究表明,草酸、柠檬酸、乙酸对4种温带典型林型土壤无机磷组分有一定影响,可以提高土壤无机磷组分的利用率。     

NaVO3+H2SO4溶液中氧气气氛下甲酸分解的研究

研究了在氧气存在下生物质催化氧化制甲酸体系中甲酸的稳定性,主要考察了反应温度、反应时间、氧气初始压力、硫酸浓度、催化剂等因素对于甲酸分解的影响。研究结果表明,温度、反应时间、硫酸浓度对甲酸的分解速率有显著的影响;氧气的初始压力对于甲酸的分解影响较小;催化剂NaVO3的存在会加速甲酸的分解。生物质催化氧化体系中,甲酸的分解反应为二级反应,甲酸分解反应的表观活化能为85.1 k J/mol。提出了在H2SO4溶液中氧气气氛下NaVO3催化甲酸分解的机理。     

Deep cleaning of a metallurgical zinc leaching residue and recovery of valuable metals

Huge quantities of zinc leaching residues (ZLRs) generated from zinc production are dumped continuously around the world and pose a potential environmental threat because of their considerable amounts of entrained heavy metals (mainly lead). Most ZLRs have not been properly treated and the valuable metals in them have not yet been effectively recovered. Herein, the deep cleaning of a ZLR and recovery of valuable metals via a hydrometallurgical route were investigated. The cleaning process consists of two essential stages:acid leaching followed by calcium chloride leaching. The optimum conditions for extracting zinc, copper, and indium by acid leaching were a sulfuric acid concentration of 200 g·L-1, a liquid/solid ratio of 4:1 (mL/g), a leaching time of 2 h, and a temperature of 90℃. For lead and silver extractions, the optimum conditions were a calcium chloride concentration of 400 g·L-1, a pH value of 1.0, a leaching time of 1 h, and a temperature of 30℃. After calcium chloride leaching, silver and lead were extracted out and the lead was finally recovered as electrolytic lead by electrowinning. The anglesite phase, which poses the greatest potential environmental hazard, was removed from the ZLR after deep cleaning, thus reducing the cost of environmental management of ZLRs. The treatment of chlorine and spent electrolyte generated in the process was discussed.     

Mechanochemical leaching of chalcopyrite concentrate by sulfuric acid

This study aimed to introduce a new cost-effective methodology for increasing the leaching efficiency of chalcopyrite concentrates at ambient temperature and pressure. Mechanical activation was employed during the leaching (mechanochemical leaching) of chalcopyrite concentrates in a sulfuric acid medium at room temperature and atmospheric pressure. High energy ball milling process was used during the leaching to provide the mechanochemical leaching condition, and atomic absorption spectroscopy and cyclic voltammetry were used to determine the leaching behavior of chalcopyrite. Moreover, X-ray diffraction and scanning electron microscopy were used to characterize the chalcopyrite powder before and after leaching. The results demonstrated that mechanochemical leaching was effective; the extraction of copper increased significantly and continuously. Although the leaching efficiency of chalcopyrite was very low at ambient temperature, the percentages of copper dissolved in the presence of hydrogen peroxide (H₂O₂) and ferric sulfate (Fe₂(SO₄)₃) after 20 h of mechanochemical leaching reached 28% and 33%, respectively. Given the efficiency of the developed method and the facts that it does not require the use of an autoclave and can be conducted at room temperature and atmospheric pressure, it represents an economical and easy-to-use method for the leaching industry.