Oxidation modification is an effective way to improve stability of materials. In this work, the semi-dry flue gas desulfurization ash was oxidized by a new method: subcritical hydrothermal heterogeneous oxidation. The effects of reaction temperature, reaction time, initial pressure and mass ratio of solid to liquid on the oxidation of desulphurization ash were studied. The results showed that the desulphurization ash can be oxidized to calcium sulfite by subcritical hydrothermal oxidation, and the oxidation effect was well. The highest oxidation rate reached 99.70%. The oxidation rate of calcium sulfite in desulfurization ash was improved by increasing the initial pressure, reaction temperature, reaction time and decreasing the mass ratio of solid to liquid. When the initial pressure was 4 MPa, the reaction temperature was 240℃, the mass ratio of desulfurization ash to water was 1:20, and the reaction time was 90 min, the oxidation rate of calcium sulfite was 92.26%. In the subcritical hydrothermal system, calcium sulfite was dissolved and ionized to form Ca2+ and SO32? firstly, then SO32? was oxidized by the free oxygen in water, and finally calcium sulfate was formed. Increasing the initial pressure and decreasing the mass ratio of solid to liquid increased the dissolution and ionization quality of calcium sulfite and then increased the oxidation rate of calcium sulfite. With the decrease of mass ratio of solid to liquid, the microstructure of the sample changed obviously from spherical to fibrous. Under the conditions of initial pressure 4 MPa, temperature 240℃, reaction time 120 min and mass ratio of solid to liquid 1:30, calcium sulfite precipitated directionally to form calcium sulfate whisker. It provided the possibility for the simultaneous synthesis of calcium sulfate whiskers by subcritical oxidation of desulfurized ash.
Rufei WEI Longzhi CHEN Hongming LONG Yifan WANG Jiaxin LI Yafei LI Ming XUAN
. Subcritical hydrothermal heterogeneous oxidation of semi-dry desulfurization ash from iron ore sintering flue gas[J]. The Chinese Journal of Process Engineering, 2019
, 19(3)
: 603
-608
.
DOI: 10.12034/j.issn.1009-606X.218291
[1] 刘征建，张建良，杨天钧．烧结烟气脱硫技术的研究与发展[J]．中国冶金，2009．
Liu Zhengjian, Zhang Jianliang, Yang Tianjun. Research and development of sintering flue gas desulphurization technology[J]. China Metallurgy, 2009, 19( 2) : 1-5( in Chinese).
[2] 贺亮，张少峰．半干法烟气脱硫技术研究现状及进展[J]．天津化工，2007(02)：18-20．
He Liang, Zhang Shaofeng. Research Status and Development of Semi-dry Flue Gas Desulfurization Technology[J]. Tianjin Chemical, 2007 (02) : 18-20( in Chinese).
[3] 陈袁魁，包正宇，龙世宗，等．高钙脱硫灰渣用作水泥原料的研究[J]．水泥工程，2006(04)：10-12．
Chen Yuankui, Bao Zhengyu, Long Shizong, et al. Study on high calcium desulfurization ash used as cement raw material[J]. Cement engineering, 2006 (04) : 10-12( in Chinese).
[4] 杨亚欣，马玉香，任爱玲，等．烧结烟气脱硫技术及脱硫产物综合利用研究进展[J]．环境科学导刊，2009(06)：67-70．
Yang Yaxin, Ma Yuxiang, Rrn Ailng, et al. Research progress on sintering flue gas desulfurization technology and comprehensive utilization of desulfurization products[J]. Environmental Science Guide, 2009 (06) : 67-70( in Chinese).
[5] 林贤熊，叶光锐．排烟脱硫副产品亚硫酸钙作水泥缓凝剂的研究[J]．粉煤灰，2003(02)：15-17．
Lin Xianxiong, Ye Guangrei. Study on calcium sulfite as a cement retarder for by-product of flue gas desulfurization[J]. Fly ash, 2003 (02) : 15-17( in Chinese).
[6] 徐胜光，李淑仪，蓝佩玲，等．燃煤烟气脱硫副产物对花生作物营养效应及其机理[J]．生态环境，2003(04)：415-418．
Xu Shengguang, Li Shuyi, Lan Peiling, et al. Nutritional Effects and Mechanism of By-products from Coal-fired Flue Gas Desulfurization on Peanut Crops[J]. ecosystem,2003 (04) : 415-418( in Chinese)
[7] 柯亮，石林，耿曼．脱硫灰渣与钾长石混合焙烧制钾复合肥的研究[J]．化工矿物与加工，2007(07)：17-20．
Ke Liang, Shi Lin, Geng Man. Study on the Preparation of Potassium Compound Fertilizer by Desulfurization Ash and Potash Feldspar[J]. Chemical minerals and processing, 2007 (07) : 17-20( in Chinese).
[8] Lancia A, Musmarra D, Pepe F. Uncatalyzed heterogeneous oxidation of calcium bisulfite[J]. Chemical Engineering Science, 1996,16(51):3889-3896.
[9] Ahmed M G, Anurag G. Characterization of the Product of the Thiosulfate Process for Desulfurization of Flue Gases[J]. Ind. Eng. Chem. Res., 1994(33):1145-1149.
[10] Li Y, Sadakata M. Study of gypsum formation for appropriate dry desulfurization process of flue gas[J]. Fuel, 1999,78(9):1089-1095.
[11] 杨剑，文娟，董凌燕，等．烟气脱硫过程锰催化氧化亚硫酸钙的研究[J]．环境工程学报，2007(09)：109-112．
Yang Jian, Wen Juan, Dong Lingyan, et al. Manganese Catalytic Oxidation of Calcium Sulfite in Flue Gas Desulfurization Process[J]. Journal of Environmental Engineering, 2007 (09) : 109-112( in Chinese).
[12] 姚璐，刘清才，方诗惠，等．半干法烧结烟气脱硫灰的氧化改性[J]．环境工程学报，2016(06)：3147-3151．
Yao Lu, Liu Qingcai, Fang Shihui, et al. Oxidation modification of semi-dry sintering flue gas desulfurization ash[J]. Journal of Environmental Engineering, 2016 (06) : 3147-3151( in Chinese).
[13] 杨新亚，张丽英，刘洪波．干法与半干法脱硫渣中亚硫酸钙的低温催化氧化的研究[J]．粉煤灰，2006(04)：10-12．
Yang Xinya, Zhang Liying, Liu Hongbo. Study on Low Temperature Catalytic Oxidation of Calcium Sulfite in Dry and Semi-dry
