NaOH-NaCl亚熔盐法活化含钾岩石制备SOD沸石_刘文卓.pdf

第 23 卷第 2 期2023年 2月过 程 工 程 学 报The Chinese Journal of Process EngineeringVol.23 No.2Feb.2023Synthesis of zeolite SOD from potassic rocks activated by NaOH-NaCl sub-molten salt methodWenzhuo LIU1,2,Yang LIU1,2,Yun LI1,2*,Hongfei GUO1,2*,Jilin CAO1,21.School of Chemical Engineering and Technology,Hebei University of Technology,Tianjin 300130,China2.Engineering Research Center of Seawater Utilization Technology of Ministry of Education,Tianjin 300130,ChinaAbstract:Potassic rocks are aluminosilicate crystals containing abundant potassium elements,which could be used to produce K-fertilizers by extracting K+,synthesizing zeolites,and preparing valuable industrial products.To realize the efficient utilization of potassic rocks,the sub-molten salt method was used to activate potassic rocks using NaOH-NaCl as the activating agent.The effects of the addition of NaOH,NaCl,and H2O on the leaching rate of K+were investigated,respectively.The raw materials,activated products and filtration were determined by X-ray diffraction(XRD),scanning electron microscopy(SEM),and titration method.The experimental results showed that the optimal activation conditions are m(NaOH)/m(potassium rocks)of 0.7,m(NaCl)/m(potassium rocks)of 0.7,m(H2O)/m(potassium rocks)of 1.0,activation temperature of 160,and activation time of 120 min.The leaching rate of K+could reach about 92%,and the alkali concentration was decreased to 41wt%.Comparative investigations were made with the effect of activation of potassic rocks using the NaOH sub-molten method concerning the leaching rate of ions of K+,SiO32 and Al3+and activated products in the identical reaction conditions.The concentrations of K+,SiO32 and Al3+in the mother liquor obtained from NaOH-NaCl sub-molten system were significantly increased in contrast with that from the system in the absence of NaCl,demonstrating the promotion effect of NaCl for the activation of potassic rocks and the peaks assigned to SOD zeolite were greatly intensified with the introduction of NaCl.Compared with the activation effect and conditions of other additives in the sub-molten salt method reported in the literature,NaOH-NaCl sub-molten system exhibited a satisfactory leaching rate of K+under the condition of significantly decreased alkali concentration at a low temperature(160)for short time(120 min),which greatly reduced energy consumption and time wasting.According to the compositions of mother liquor after sub-molten salt activation,the circulating process for the activation of potassic rocks in the NaOH-NaCl mixed sub-molten salt system was designed to realize the recycling of NaCl.This work provides an energy-saving and effective method for the activation of potassic rocks,paving a new way to realize the comprehensive utilization of potassic rocks.Key words:potassic rocks;sub-molten salt method;NaOH-NaCl;leaching rate of K+;zeolite SOD;ion exchange研究论文DOI:10.12034/j.issn.1009-606X.222081收稿：2022-03-11，修回：2022-04-26，网络发表：2022-06-08；Received:2022-03-11,Revised:2022-04-26,Published online:2022-06-08基金项目：国家自然科学青年基金资助项目(编号：22008049)；河北省自然科学青年基金资助项目(编号：B2020202081)；2021年河北省研究生创新资助项目(编号：CXZZSS2021036)作者简介：刘文卓，硕士研究生，化学工程专业，E-mail:；通讯联系人，李雲，讲师，研究方向为精细无机品合成及多相催化，E-mail:；郭宏飞，副教授，研究方向为功能聚合物材料合成，E-mail:引用格式引用格式：刘文卓,刘洋,李雲,等.NaOH-NaCl亚熔盐法活化含钾岩石制备SOD沸石.过程工程学报,2023,23(2):263271.Liu W Z,Liu Y,Li Y,et al.Synthesis of zeolite SOD from potassic rocks activated by NaOH-NaCl sub-molten salt method(in Chinese).Chin.J.Process Eng.,2023,23(2):263271,DOI:10.12034/j.issn.1009-606X.222081.NiK+Na+O22+OOH Cl Potassic rocksNaOHNaCIEvaporation and concentrationHClFilter liquorCaCl2CaSiO3FiltrationActivationThe schematic mechanism of potassium extractionBy product of SOD zeoliter liquorK+Na+Na+OH Cl 过 程 工 程 学 报第 23 卷 NaOH-NaCl亚熔盐法活化含钾岩石制备SOD沸石刘文卓1,2，刘 洋1,2，李 雲1,2*，郭宏飞1,2*，曹吉林1,21.河北工业大学化工学院，天津 3001302.教育部海水资源高效利用化工技术工程研究中心，天津 300130摘要：为了实现含钾岩石的高效利用，以NaOH-NaCl混合碱为助剂进行亚熔盐法活化含钾岩石的研究。采用X射线衍射(XRD)、扫描电镜(SEM)及滴定法对反应前后的产物组成进行分析。结果表明，含钾岩石活化的适宜条件为：m(NaOH)/m(potassic rocks)=0.7、m(NaCl)/m(potassic rocks)=0.7、m(H2O)/m(potassic rocks)=1.0、反应温度160，反应时间120 min。在该条件下，K+浸出率可达92%，碱浓度下降至41wt%，低于常规亚熔盐体系的介质浓度，活化后产物为SOD沸石。通过分析合成后母液组成，设计母液的循环工艺，实现NaCl的循环利用。该法显著减少了亚熔盐活化含钾岩石过程中的碱用量，并实现矿石的高效活化，为含钾岩石的综合利用提供新途径。关键词：含钾岩石；亚熔盐法；NaOH-NaCl；K+浸出率；SOD沸石；离子交换中图分类号：TQ424.25 文献标识码：A 文章编号：1009-606X(2023)020263091 前 言 钾肥是农作物生长所需的重要肥料之一，使用钾肥后农作物的产率可提升至 20%30%。我国是农业大国，每年需要大量的可溶性钾资源，但我国可溶性钾资源稀缺(只占世界上总钾资源的2.2%)，因此，接近50%的钾肥需要依赖进口1-4。我国矿产资源丰富，近年来矿石资源尤其是低品位矿的开发利用得到了广泛研究5,6。我国含钾岩石储量丰富，是一种不溶性钾资源，具有超过200亿吨的K2O。因此，充分开发利用钾长石中的钾资源是解决可溶性钾资源短缺的有效方法7-10。含钾岩石(Potassic Rocks)是由AlO45和SiO44四面体组成的具有独特三维网状结构的硅铝酸盐晶体。K+分布在三维骨架的孔隙或通道中以平衡骨架Al带来的负电荷，稳定性极强，需要在超过1000的高温下才能将其破坏11。目前含钾岩石的活化方法主要包括焙烧法12,13、水热法14、酸浸法15、微生物法16、亚熔盐法17-23等。其中，亚熔盐法因具有低蒸汽压、高沸点、高反应活性及可控性得到广泛应用17。亚熔盐是一种高浓度碱金属盐的非常规介质，在活化过程中，OH解离生成大量高活性氧负离子(O2)，O2沿着特定的晶面方向发生迁移并与钾长石晶格在反应界面发生交互取代作用，使得钾长石结构被破坏，从而达到分解钾长石的目的18。目前，NaOH强碱型亚熔盐体系活化含钾岩石效果较佳，王颖等17使用浓度为60wt%的NaOH溶液活化含钾岩石，在温度为 160、液固比为 4:1 的条件下反应140 min，获得 98%的 K+溶出率。Miao 等19首次采用NaOH-KOH-H2O混合碱体系作为亚熔盐介质在1