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构建长度、直径相同的SK、SX型静态混合器,利用Polyflow软件模拟低密度聚乙烯(LDPE)熔体在静态混合器内的流动情况,得到2种静态混合器的示踪粒子分布图、压降、分离尺度等参数,分析了流量对压力和分离尺度的影响,以及分离尺度下降一半,2种静态混合器所需的压降和流程长度。结果表明,随流程长度的增大,SX型静态混合器的粒子分布更加均匀,分离尺度更小,在出口处分离尺度约为SK型的1/3;当流量增至初始值的10倍时,SK和SX型的压降分别增至原来的7.4和4.7倍,两者出口处的分离尺度分别变化了8.3%和60%;随着混合过程的进行,分离尺度每下降1/2,所需压降及流程长度逐渐增大。 相似文献
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Research on leaching rate enhancement and organic matter removal in wet-process phosphoric acid 下载免费PDF全文
In the process of wet-process phosphoric acid leaching, the product phosphoric acid appears black due to the incomplete carbonization of some organic matter. A novel type of catalytic oxidation wet-process phosphoric acid purification technology was proposed in this work. During the leaching process, the oxidant (H2O2) and catalyst (MnO2) was added to form the peroxides such as ·OH and HO2· in the transformation process, which can enhance the removal rate of organic matter and strengthen the leaching rate of phosphate rock. The different reaction conditions that affected the leaching rate of wet-phosphoric acid and the removal of organic matter were investigated. The results indicated that 96.9% of phosphate rock were leached under the optimum conditions of H2O2 dosage 0.08 ml/g, MnO2/P mass ratio of 0.04, 80℃ and for 40 min. At the same time, the TOC remove rate reached 79%. The analysis mechanism showed that H2O2 will form H3PO4 · H2O2 peroxide with H3PO4 in the solution, and MnO2 will react with it like Fenton to generate a large amount of ·OH, and then fully oxidized the black organic matter into CO2 and H2O. Organic matter “wrapped” on the surface of the phosphate rock is broken by ·OH, which promoted the leaching of phosphoric acid and enhanced the removal of organic matter. 相似文献
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Wax esters were synthesized in a solvent free system catalyzed by immobilized lipase from Candida sp. 99-125, with oleic acid and cetyl alcohol. The effects of substrate molar ratio, lipase dosage and water removal were investigated in a 50 ml flask incubated in a thermostatic cultivation cabinet. The optimized conditions were: temperature 40 ℃, shaking at 170 r·min-1, acid/alcohol molar ratio 1:0.9, lipase dosage in 10% (by mass) of oleic acid, and open reaction for water removal. As a result, the conversion rate reached 98% for reaction of 8 h. The volume of reactor was scaled up to 1 L three-neck flask. The optimized parameters were: 200 r·min-1 agitation speed, 2.5% (by mass) lipase dosage, others were the same as the parameters described above. The conversion rate reached 95% for reaction of 24 h. The lipase retained 46% conversion rate after reuse for 6, 7 batches. The products were purified by removing remained cetyl alcohol and fatty acids with ethanol and saturated sodium carbonate so-lution, respectively. The purity of the wax ester, cetyl oleate, was 96%. The physical and chemical properties of cetyl oleate were tested and compared with those of jojoba oil. The results show that the product cetyl oleate has great potential to use as the substitute of natural jojoba oil. 相似文献
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运用恒电流法在铜柱电极上研究了工业磷酸中毒性较大的As(Ⅲ)还原为无毒单质砷的电化学行为。实验表明,当电流密度控制在-0.044 mA/cm2以内时可以很好地将As(Ⅲ)转化为单质砷并抑制砷化氢析出。由塔费尔拟合推算得到As(Ⅲ)转化为单质砷的交换电流密度为-6.324×10-7mA/cm2,此过程为不可逆过程。采用表面积为15.8 cm2的铜柱电极,在电流密度为-0.038 mA/cm2,温度为80℃条件下,将磷酸中As(Ⅲ)含量由10.92×10-6降到0.47×10-6,电流效率达7.55%。 相似文献
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己二酸氨化法是工业上生产己二腈的重要方法之一,其中和反应步骤受气液相传质影响很大。采用体积为1 L的半间歇式反应釜,对己二酸中和反应的宏观动力学进行了研究。在磷酸质量分数为0.2%、搅拌速率为1800 r·min-1、氨气流量为600 L·h-1的条件下,实验考察了210~260℃范围内温度对己二酸浓度随时间变化的影响。由实验数据拟合结果表明:在250℃己二酸浓度大于0.1 mol·L-1时为传质控制阶段,中和反应对于己二酸为一级,反应活化能为42.9 kJ·mol-1;在250℃己二酸浓度小于0.1 mol·L-1时为反应控制阶段,中和反应对于己二酸为二级,反应活化能为52.7 kJ·mol-1。模型计算值与实验值相吻合,并结合理论模型得出对己二酸的本征反应级数为二级。保持总压(略大于常压)、温度260℃、搅拌速率1800 r·min-1和磷酸质量分数0.2%保持不变,在氨气流量为200~600 L·h-1的范围内考察了氨气分压对己二酸浓度随时间变化的影响,动力学拟合结果表明对氨气分压的本征反应级数为一级。 相似文献
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Iron element is one of the main impurities in wet-process phosphoric acid and it has a significant impact on the subsequent phosphorus chemical products. This paper studied the feasibility of using Sinco-430 cation exchange resin for iron removal from phosphoric acid. The specific surface area and the total exchange capacity of resin were 8.91 m~2·g~(-1) and 5.18 mmol·g~(-1), respectively. The sorption mechanism was determined by FTIR and XPS and the results indicated that iron was combined with-SO_3 H in resin. The removal process was studied as a function of temperature, H_3 PO_4 content and mass ratio between resin and solution. The unit mass of resin to remove iron was 0.058 g·g~(-1) resin when the operating parameters were T = 50 ℃, H_3 PO_4 content = 27.61 wt%and S/L = 0.1, respectively. Kinetics study demonstrated that pseudo-second-order reaction model fits this study best and the calculated activation energy of overall reaction is 29.10 kJ·mol~(-1). The overall reaction process was mainly controlled by pore diffusion. 相似文献
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采用铁粉还原脱除电解锰阳极液中的硒,考察了各主要因素对硒脱除率的影响,研究了硒脱除过程的动力学。结果表明,锰阳极液中硒的脱除速率随反应时间、铁粉用量、反应温度的增加而增加,随硫酸用量的增加而减少。XRD与SEM分析表明,反应温度对硒渣结构影响最大,30℃反应后渣中存在Se、Fe、FeSe2、Fe2(SeO4)34种物相,硒的结晶形态以纺锤形为主;90℃反应后渣中存在Se、FeSe2两种形式,硒的结晶形态以球形为主。铁粉还原脱除锰阳极液中硒的动力学过程符合一级反应速率规律,属固体产物层扩散控制,表观活化能为15.94 kJ·mol-1。 相似文献
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二水法湿法磷酸中常含有一定量硫酸根杂质,硫酸根的存在不仅降低了磷酸品质,而且增加了磷酸对硫酸的消耗。采用磷精矿为脱硫剂,研究了脱硫剂用量、反应时间、反应温度对湿法磷酸中硫酸根脱除的影响,并测算了二水硫酸钙在湿法磷酸中的溶度积。结果表明:固液质量比为5%的磷精矿粉可有效地脱除稀磷酸中的硫酸根,反应温度建议不超过70 ℃,反应2 h即可。此外,在稀磷酸中测算硫酸钙的溶度积为2×10-2~3×10-2。该研究对湿法磷酸生产过程中在降低硫酸根含量并提高湿法磷酸品质方面具有一定的指导意义。 相似文献
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在湿法磷酸浸出过程中由于部分有机物碳化不彻底,使产品磷酸呈现黑色。本文提出了一种新型的催化氧化湿法磷酸净化技术,即在湿法磷酸浸出过程中引入氧化剂(H2O2)及催化剂(MnO2),基于转化过程中形成的 和 等过氧化物实现对有机物的去除与浸出过程的强化。重点考察不同反应条件对湿法磷酸浸出率及有机质去除的影响。结果表明,浸出时间为40 min、反应温度为80℃、H2O2用量为0.08 ml/g、催化剂与磷矿的质量比为0.04时,磷矿浸出率可达96.9%;同时测定得到的TOC去除率达到79%。分析机理可得,H2O2会与溶液中的H3PO4形成H3PO4·H2O2过氧化物,MnO2与之发生类Fenton反应,产生大量 ,进而将黑色有机物充分氧化为CO2和H2O,打破有机物对磷矿颗粒表面的“包裹”,促进磷酸的浸出和有机物的去除。 相似文献
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为改进湿法磷酸生产工艺,提高副产磷石膏的品质,减少湿法磷酸固体副产物堆存产生的经济和环境压力,进行了工业磷酸分解磷矿制磷酸的实验,同时对固体副产物的性质进行了分析。工业磷酸分解磷矿制磷酸的工艺分为两步:第一步,工业磷酸与磷矿反应,得到磷酸二氢钙溶液和酸不溶渣;第二步,浓硫酸与磷酸二氢钙溶液反应,得到磷酸溶液和高纯石膏。采用单因素实验考察了酸比(工业磷酸用量与理论磷酸用量的物质的量的比值)、磷矿粒度、反应温度和反应时间对磷矿中磷浸出率的影响。得到磷矿酸解适宜工艺条件:酸比为6.8,磨矿细度为小于0.074 mm粒级占60%,反应温度为50 ℃,反应时间为2.5 h。在此条件下,磷矿中磷的浸出率可达87.69%。磷矿酸解制磷酸产生的固体副产物中石膏占35.32%(质量分数)、酸不溶渣占64.68%(质量分数)。制备的高纯石膏的纯度为95.80%,工业利用价值较高,有利于提高湿法磷酸固体副产物的利用率。 相似文献