铬盐清洁工艺亚熔盐介质脱除铝酸钾、碳酸钾研究I.——溶解度

脱除铝酸钾、碳酸钾等杂质是铬盐清洁工艺亚熔盐介质循环利用的重要环节.作者测定了40℃及95℃KOH-K2CO3-Al2O3-SiO2-H2O体系部分溶解度,确定该体系存在K2O·Al2O3·3H2O(即 KAlO2·1.5H2O)与K2CO3·1.5H2O等平衡固相,为亚熔盐介质的冷却结晶除杂过程控制提供了热力学依据和指导.     

铬盐清洁工艺亚熔盐介质脱除铝酸钾、碳酸钾研究Ⅱ结晶工艺

针对铬盐清洁工艺亚熔盐介质净化过程,研究了KOH-K2CO3-Al2O3-SiO2-H2O体系铝酸钾、碳酸钾混合盐的结晶行为.发现冷却时间、搅拌速率、冷却方式对结晶平均粒径具有重要影响,对晶种浓度也有一定影响.与控制冷却相比,线性冷却方式产生的结晶粒径稍小,除杂效果较好.在最佳工艺条件下亚熔盐介质中碳酸钾、铝酸钾的质量分数可分别降至4.67%、0.98%(以Al计),实现了亚熔盐介质的有效净化.     

铬盐新用途——亚铬酸钠及熔盐电池简介

根据专利及相关文献,介绍了铬盐的新用途,即以亚铬酸钠为正极活性物质的熔盐蓄电池。熔盐电池制备方法:以亚铬酸钠为熔盐电池的正极活性物质,以锡钠合金或锌钠合金为负极活性物质,夹在两种活性物质之间的隔膜采用事先含浸了二氟磺酰胺钠-二氟磺酰胺钾熔融盐的玻璃布。熔盐电池性能:放电容量高,能量密度达到290 W·h/L,是同体积锂电池的2倍;比容量为124 m A·h/g,充放电1 000次后电池容量仍有76%。熔盐电池应用领域:由于熔盐电池需保持温度为80℃才可正常工作,因此可用于需要长期不间断工作的领域,如家庭供电、电动汽车以及办公楼和工厂的备用电源。并且介绍了亚铬酸钠的制备方法。     

METSIM在亚熔盐铬盐清洁生产工艺流程设计中的应用

针对亚熔盐铬盐清洁生产工艺能耗大、热利用率低的问题及工艺放大的需求,采用METSIM软件对此工艺进行了物料和能量衡算,得到了各股物流的详细信息,为工艺放大提供参考;采用夹点技术进行换热网络优化,优化后的热交换网络可使热公用工程及冷公用工程用量分别减少31.5%和31.7%,总热利用率提高11.0%.     

氢氧化钠亚熔盐体系分解铬铁矿的工艺研究

研究了氢氧化钠亚熔盐体系氧压浸出铬铁矿工艺的主要作用因素对铬浸出率的影响,确定了最佳的工艺参数。结果表明,氢氧化钠亚熔盐氧压浸出过程,对铬浸出影响最显著的因素是温度和氧压力;在铬铁矿粒径为0.038~0.048 mm、矿碱质量比为1∶7、 搅拌速度为650 r/min条件下,氢氧化钠亚熔盐氧压浸出铬的最佳反应条件为：浸出温度为245 ℃、碱浓度为65%（质量分数）、氧气压力为0.8 MPa、反应时间为480 min。在该条件下铬的浸出率为99%以上,活化能为51.49 kJ/mol,动力学方程为1-2/3x-（1-x）2/3=2 124.73 P■ 0.85×e-51 490/RT×t。     

我国铬盐生产状况及发展建议

简要介绍我国铬盐生产的发展过程、工艺状况及铬渣治理状况,对铬盐生产提出了发展建议。     

A new method of potassium chromate production from chromite and KOH‐KNO3‐H2O binary submolten salt system

A new method of chromate production by applying a new reaction system of KOH‐KNO₃‐H₂O (binary submolten salt system) is proposed and proved feasible. Under conditions of temperature 350°C, KOH‐to‐chromite ore ratio 2:1, stirring speed 700 rpm, KNO₃‐to‐chromite ore ratio 0.8:1, oxygen partial pressure 50%, and gas flow 1 L/min, chromium conversion ratio obtained is >98% with reaction time around 300 min. The decomposition of chromite ore in the system is a typical process of solid– liquid–gas reaction, which is coordinately controlled by mass diffusion in product layer and interface reaction. Apparent activation energy of decomposition in the temperature range from 280 to 370°C is 55.63 kJ/mol. During reaction, oxygen dissolves into KOH‐KNO₃‐H₂O melt system first and some cluster, e.g. O, is formed and the mass diffusion coefficient of the cluster was calculated. The system can be considered as both a media of oxygen transportation and reactant donator. Potassium nitrate plays a role of catalyst in the oxidation decomposition reaction of chromite ore and potassium hydroxide. © 2009 American Institute of Chemical Engineers AIChE J, 2009     

铬酸铬渣生产铬鞣剂过程除铁技术研究进展

铬鞣剂被认为是目前制造轻革的重要材料,以铬酸铬渣为原料生产铬鞣剂是低成本的生产方法之一,但是以含铁的铬酸铬渣作原料生产铬鞣剂会影响铬鞣剂产品的质量。详细介绍了有机络合法、萃取法等在铬鞣剂生产中除铁的应用,从反应原理、工艺流程和除铁效果等几个方面对各种方法进行了对比,评价使用不同生产方法的技术优劣,并对低含铁铬鞣剂的应用前景做了展望。     

用盐水溶液浸取新工艺铬渣研究

针对中科院过程所开发的铬铁矿液相氧化生产铬酸钾工艺过程中产生的一种含铬固体废物,采用硫酸铵、硫酸钠、氯化铵、氯化钠及其混合水溶液浸取的方法对其进行解毒处理。利用配方实验设计方法,通过间歇浸取实验表明,这些盐溶液对该铬渣中的六价铬浸取效果并无明显差别,效果与USEPA Method 3060A碱浸取方法相当。进一步用均匀设计方法考察了浸取时间、硫酸铵浓度以及浸取温度对浸取效果的影响,结果表明,硫酸铵最佳浓度约为1.5 mol/L,六价铬浸取量随温度升高而明显增大。     

Factors affecting the solubility of gypsum. The effect of lime and temperature in different media

The effect of lime on the solubility of gypsum in water and in sodium hydroxide solution at 30, 60 and 100°C has been studied turbidimetrically and by means of X-ray diffraction analysis. Lime depressed the solubility of gypsum in water only slightly at 30°C and a rise of temperature minimised its effect until its complete elimination. In the absence of alkali the minimum sulphate ion concentration in a supersaturated lime solution and at temperatures in the range 30–100°C is about 1.2gdm⁻³. In sodium hydroxide solution neither lime nor temperature played a significant role and the solubility of gypsum was clearly promoted. At temperatures in the range 30–100°C, 0.5g of gypsum dissolved in 100cm³ of 0.2MNaOH solution.     

湿法磷酸净化及其盐类生产技术:4.技术创新集成生产磷酸氢钙

概述钙盐净化WPA原理、二段中和法生产磷酸氢钙(DCP)的传统方法。该法生产的DCP质量达到国际先进水平,但存在原料消耗高等问题。介绍采用磷矿粉脱硫、"节硫降钙"、选用钙盐净化WPA和2次中和除氟以减少P2O5损失和副反应发生、溶解白磷肥回收其中的P2O5、母液净化回收磷等一系列技术创新,可提高磷回收率,降低原料消耗,使DCP制造成本下降约10%。     

Kinetics of release of particulate solutes incorporated in cellulosic polymer matrices as a function of solute solubility and polymer swellability. I. Sparingly soluble solutes

A comparative study has been made of the kinetics of release into water of simple hydrophilic, but sparingly soluble, solutes (exemplified by CaSO₄ or SrSO₄) incorporated in varying amounts in cellulosic polymer matrices of low or high water swellability. Hydrophobic cellulose acetate films (cast from an acetone dope containing a dispersion of the appropriate salt particles occupying a fractional volume ϵ_N = 0.1–0.4 in the loaded hydrated matrix) were found to be particularly useful for this purpose because they could be easily hydrolyzed to cellulose, thus producing hydrophilic polymer matrices containing identical amounts and distributions of solute particles. The kinetic behavior observed exhibited the same main features as previously noted in drug release studies. Thus, a √t kinetic law was obeyed in all cases (apart from a relatively short initial period), while the diffusion coefficient calculated by application of the Higuchi model tended to rise with increasing solute load. This tendency was very strong in the case of the hydrophobic weakly swollen matrix and much weaker in the case of the hydrophilic one. On the reasonable assumption that the diffusion of solute in the salt-depleted matrix (which controls the release rate) occurs via aqueous pathways, the tortuosity τ of these pathways was calculated and found to attain extremely high values in the case of lightly loaded (ϵ_N = 0.1) matrices. These high τ values were drastically reduced upon either (1) increase of the salt load or (2) hydrolysis to cellulose. This behavior is shown to result from the fact that at ϵ_N = 0.1, the salt particles were fully coated with cellulose acetate so that water taken up to fill the space vacated by released salt is in the form of globules dispersed in a weakly hydrated polymer matrix and, hence, is ineffective in providing continuous aqueous pathways. In (1), these globules are increasingly bridged by gaps left in the original loaded matrix, as a result of incomplete coating of the solute particles with polymer. In (2), bridging is similarly effected by the formation of aqueous pathways through the polymer when its degree of hydration is sufficiently increased. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67: 277–287, 1998     

湿法磷酸净化及其盐类生产技术:3.化学净化WPA肥、饲钙和磷酸盐联产新技术

简述化学法除去湿法磷酸(WPA)杂质净化原理及其净化过程;分析传统净化WPA生产三聚磷酸钠(STPP)的技术之不足;介绍不用钡盐脱硫减少硫酸用量、回收氟硅酸盐、节约原辅材料消耗等新技术。WPA化学净化肥、饲钙和磷酸盐联产新技术的优势是:降低生产饲钙和磷酸盐的原料和能源消耗,提高WPA使用和其净化副产物利用的附加值,提高产品质量和经济效益。该新技术的能耗和生产成本比以黄磷(P4)为原料或溶剂净化WPA下降10%～40%。新技术也可用于磷酸钾、磷酸铵盐生产。     

A comparison of the results obtained from grinding in a stirred media mill lignite coal samples treated with microwave and untreated samples

Various studies have been carried out on the effect of microwave-treatment on grinding different types of coal. However, the effect of microwave treatment on grinding coal samples −3.35 mm in size which can be considered to be fine is still under investigation. The purpose of this paper is to make contributions to these studies conducted. In the study, lignite coal samples with pyritic sulphur and 25% structural moisture were crushed below −3.35 mm particle size using jaw and cone crushers and then classified into three different mono size groups by Russel sieve. For a complete removal of the structural moisture from the lignite coal, a microwave application with 600 W needs approximately 35% more energy consumption than that with 850 W. The untreated coal samples and the ones treated with microwave at 850 W were ground for 5, 15, 30, 60, 120 s in a stirred media mill. The breakage rates of microwave-treated coal increased and accordingly the ground products of microwave-treated coal yielded finer particles than −106 μm as compared to untreated coals. The untreated and microwave-treated feed coals of −3350 μm and −1180 μm particle sizes were ground for 2 min in the stirred media mill. It was found that the increases in the rate of weight percentages for −106 μm particle size fraction after 2 min of grinding of untreated and microwave-treated feed coals of −3350 μm and −1180 μm were found to be 15.81% and 2.69%, respectively. Moreover, Hardgrove Index (HGI) test results of lignite coal showed that the HGI index value increased by approximately 23% after microwave treatment with 850 W.