摘要
为提升废阴极炭氟的稳定化水平,对铝土矿选尾矿的共焙烧体系进行了试验研究和模拟计算,考察了焙烧温度、预处理和添加剂对氟迁移转化的影响.结果显示,在废阴极炭/尾矿质量比为1:4、焙烧温度为800℃、停留时间为1h的条件下,氟主要以CaF_(2)形式进入底渣,底渣中氟浸出浓度为22.96 mg·L^(-1),远低于《危险废物鉴别标准-浸出毒性鉴别》(GB 5085.3-2007)规定的100 mg·L^(-1).Factsage7.1模拟结果显示,在SiO_(2)和Al2O_(3)存在下,Na_(3)AlF_(6)和NaF与含钙物质(如CaO)的反应优先于与H_(2)O(g)的反应,使氟分别转化为CaF_(2)和气态氟(如HF(g)),并生成了反应副产物NaAlSiO_(4).球磨预处理(时间为4 h)有效降低废阴极炭和尾矿的粒径,使得氟反应充分进行,氟浸出浓度降至19.61 mg·L^(-1).尾矿经700℃预先焙烧(时间为1h),尾矿中水合氧化物有效分解,使得在与废阴极炭共焙烧过程中产生的H_(2)O(g)含量下降,使氟气化率下降了7.30%,更多氟保留在底渣中,氟浸出浓度升至36.97 mg·L^(-1).在CaO和CaSO_(4)按质量分数10%添加的情况下,共焙烧体系的钙氟比提高,有利于CaF_(2)的生成,氟浸出浓度分别降至12.75 mg·L^(-1)和11.52 mg·L^(-1).另外,在Al_(2)(SO_(4))_(3)按质量分数10%添加的情况下,气态氟组分向单一的HF(g)转化,氟浸出浓度降低至22.01 mg·L^(-1).综合来看,选尾矿与废阴极炭的共焙烧有利于氟的稳定化,并同时形成NaAlSiO_(4)和Fe3O_(4),为废阴极炭的无害化处理和综合利用提供了技术支持.
To enhance the stabilization level of fluorine in spent pot lining,experimental research and simulation calculations were conducted on the coroasting system of bauxite tailings.The effects of roasting temperature,pretreatment,and additives on the migration and transformation of fluorine were investigated.The results showed that under the conditions of a spent pot lining/tailings mass ratio of 1∶4,roasting temperature of 800℃,and residence time of 1 hour,fluorine mainly entered the bottom slag in the form of CaF_(2),with a fluorine leaching concentration of 22.96 mg·L^(-1),significantly lower than the limit of 100 mg·L^(-1)specified in the"Identification Standards for Hazardous Waste-Leaching Toxicity"(GB 5085.3-2007).The simulation results using Factsage 7.1 indicated that in the presence of SiO_(2)and Al2O_(3),the reactions between Na_(3)AlF_(6),NaF,and calcium-containing substances(such as CaO)took precedence over the reaction with H_(2)O(g),resulting in the conversion of fluorine into CaF_(2)and gaseous fluorine(e.g.,HF(g)),along with the generation of a byproduct,NaAlSiO_(4).Through a 4-hour ball milling pretreatment,the particle size of spent pot lining and tailings was effectively reduced,enabling sufficient fluorine reaction and lowering the fluorine leaching concentration in the bottom slag to 19.61 mg·L^(-1).Additionally,pre-roasting the tailings at 700℃for 1 hour effectively decomposed the hydrated oxides in the tailings,resulting in a decrease of 7.30%in fluorine volatilization rate during co-roasting with spent pot lining,leading to a higher retention of fluorine in the bottom slag and an increased leaching concentration of 36.97 mg·L^(-1).The addition of 10%CaO and CaSO_(4)in the co-roasting system improved the calcium-to-fluorine ratio,facilitating the generation of CaF_(2)and reducing the fluorine leaching concentrations to 12.75 mg·L^(-1)and 11.52 mg·L^(-1),respectively.Furthermore,the addition of 10%Al_(2)(SO_(4))_(3)resulted in the conversion of gaseous fluorine into a single HF(g)component,lowering the fluorine leaching concentration to 22.01 mg·L^(-1)in the bottom slag.In conclusion,the co-roasting of tailings and spent pot lining is beneficial for the stabilization of fluorine and simultaneously promotes the formation of NaAlSiO_(4)and Fe3O_(4),providing technical support for the harmless treatment and comprehensive utilization of spent pot lining.
作者
江海灵
谢武明
李瑜辉
卞求实
林晓燕
刘敬勇
JIANG Hailing;XIE Wuming;LI Yuhui;BIAN Qiushi;LIN Xiaoyan;LIU Jingyong(School of Environmental Science and Engineering,Guangdong University of Technology,Guangzhou 510006)
出处
《环境科学学报》
CAS
CSCD
北大核心
2024年第1期341-351,共11页
Acta Scientiae Circumstantiae
基金
国家自然科学基金(No.42277365)
广东省自然科学基金(No.2021A1515010496)。
关键词
铝土矿选尾矿
废阴极炭
焙烧
迁移转化
氟稳定化
bauxite tailings
spent pot lining
roasting
migration and transformation
fluoride stabilization
