RESOURCE REUTILIZATION FOR PHOSPHOGYPSUM AND RED MUD THOUGH CO-TREATMENT
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摘要: 磷石膏和赤泥是典型的2大工业废渣,排放量大、成分复杂、环境风险高,再利用难度较大。基于磷石膏属高钙碱性,赤泥为富铝硅酸性的矿物特点,采用两渣协同处理实现钙质循环再用同步回收铝钠的技术思路。小试试验结果表明:最适宜工艺条件为烧结温度850 ℃,2倍还原剂理论添加量,C/S=2.1,N/A=1.1,烧结时间7 min,该条件下铝和钠的回收率分别为82.14%和83.48%。在此条件下进行了中试试验,结果表明:相较于小试试验,中试试验获得的铝钠回收率略低(Al2O3 76.32%,Na2O 81.25%);其烧结熟料及浸出渣XRD分析表明,与熟料比较,渣中铝酸钠峰值减弱,而钙硅等化合物峰值加强,表明熟料中铝钠溶出效果良好,钙硅等化合物进入渣相;从SEM图可见,熟料微观形貌疏松,表明烧结质量良好;而浸出渣粒度变细、分散,表明熟料浸出性能优异;采用碳酸化分解溶出工序制备的铝酸钠溶液,所得Al(OH)3产品相比氧化铝企业种分工艺生产的Al(OH)3,两者Al2O3含量相当,但前者纯度更低,这可能是源于原料和工艺的差异,且浸出渣碱含量较高(Na2O 3.19%),制约了其大规模利用。试验验证了两渣高温协同处理资源化利用的技术思路可行,但该技术在制备合格Al(OH)3产品及降低渣中碱含量方面仍需进一步优化。Abstract: Phosphogypsum (PG) and red mud (RM) are two kinds of solid residue. Up to date, however, the approach to efficient utilization for the two residues faces technical difficulties due to their large emissions, complex composition, and high environmental risk. Based on the mineral characteristics that PG is a basic waste with high calcium, and RM is an acid residue with high alumina and silica, we proposed an innovative approach to recycle calcium and recover aluminum and sodium simultaneously by con-treating the two residues at high temperatures. The results of the laboratory-scale test showed that the optimum parameters for co-processing of PG and RM were sintering temperature 850 ℃, twice stoichiometric amount of reductant, n(CaO)/n(SiO2)=2.1, n(Na2O)/n(Al2O3)=1.1, and sintering time of 7 minutes. Under these conditions, the recovery rates of aluminum and sodium were 82.14% and 83.48%, respectively. Moreover, the pilot test was carried out under this condition. The results showed that the recovery rates of aluminum and sodium were slightly lower (76.32% for Al2O3, and 81.25% for Na2O) than those of the laboratory-scale test; XRD analysis of the sintered sample and its corresponding leached residue showed that the peak value of Na/Al-bearing materials was weakened, while the diffraction peaks of Ca-Si compounds in the residue became stronger compared with the sintered sample, indicating that the sodium aluminate in the sintered product was effectively dissolved, and the insoluble Ca-Si materials were enriched in the residue. Furthermore, the morphology of the two samples was observed by SEM, the sintered product presented large agglomerated particles with loose structure, while most of the large agglomerate disappeared in the leached residue, indicating that soluble Na- and Al-bearing compounds were dissolved out, which agreed well with the observed XRD results. Moreover, the sodium aluminate solution obtained by the leaching process was treated by the carbonation decomposition to produce Al(OH)3. Compared to the Al(OH)3 supplied by a large aluminum plant in Guizhou, the two products both contain similar Al2O3 content, but the former was with higher impurity content present, which may be due to the differences between the raw materials and processes. The results show that the novel idea for resource re-utilization of phosphogypsum and red mud through a co-treatment process is feasible. However, the leached residue is difficult for further utilization due to its high alkali content (approximately 3.19% Na2O). Therefore, this technology still needs to be optimized for a high-purity refined Al(OH)3 product and leached residue with a low alkali content.
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Key words:
- phosphogypsum /
- red mud /
- con-treatment /
- resource utilization /
- pilot test
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[1] KUZMANOVIĆ P, TODOROVIĆ N, FORKAPIĆ S, et al.Radiological characterization of phosphogypsum produced in Serbia[J]. Rradiat phys chem, 2020,166:108463. [2] CUI R Z, BAI H D, GAO Y F, et al. Current situation of comprehensive utilization of phosphogypsum and its development trend of 14th Five-Year Plan[J]. Inorganic Chemical Industry, 2022,54(4):1-4. [3] 崔荣政,白海丹,高永峰,等.磷石膏综合利用现状及"十四五"发展趋势[J].无机盐工业,2022,54(4):1-4. [4] 张杰, 邹洪涛, 宋锡高.黔南州磷石膏综合利用现状及建议[J].磷肥与复肥, 2019,34(1):38-40. [5] 王志凯,王贻明,吴爱祥,等.堆存温度对半水磷石膏胶凝性能影响[J].工程科学学报,2022,44(5):840-848. [6] JALALI J, GAUDIN P, CAPIAUX H, et al. Fate and transport of metal trace elements from phosphogypsum piles in Tunisia and their impact on soil bacteria and wild plants[J]. Ecotoxicol Environ Saf, 2019,174:12-25. [7] 刘林程,左海滨,许志强.工业石膏的资源化利用途径与展望[J].无机盐工业,2021,53(10):1-9. [8] YANG X S, ZHANG Z Y, WANG X L, et al. Thermodynamic study of phosphogypsum decomposition by sulfur[J]. J Chem Thermodyn, 2013,57:39-45. [9] 马丽萍.磷石膏资源化综合利用现状及思考[J].磷肥与复肥, 2019,34(7):5-9. [10] DING W J, CHEN Q J, SUN H J, et al. Modified mineral carbonation of phosphogypsum for CO2 sequestration[J]. J CO2 Util, 2017,34:507-515. [11] SAADAOUI E, GHAZEL N, BEN ROMDHANE C, et al. Phosphogypsum:potential uses and problems:a review[J]. Int J Environ Stud,2017, 6:1-10. [12] CÁNOVAS C R, CHAPRON S, ARRACHART G. Leaching of rare earth elements (REEs) and impurities from phosphogypsum:a preliminary insight for further recovery of critical raw materials[J]. J Cleaner Prod, 2019,219:225-235. [13] 叶学东.2019年我国磷石膏利用现状及形势分析[J].磷肥与复肥,2020,35(7):1-3. [14] LI R B, ZHANG T A, LIU Y, et al. Calcification-carbonation method for red mud processing[J]. J Hazard Mater, 2016,316:94-101. [15] SHEN X H, YAN F, ZHANG Z, et al. Enhanced and environment-friendly chemical looping gasification of crop straw using red mud as a sinter-resistant oxygen carrier[J].Waste Management, 2021,121:354-364. [16] 王亚光,刘晓明.赤泥基光催化材料降解水中有机污染物的应用现状及发展趋势[J].工程科学学报,2021,43(1):22-32. [17] QU Y, LI H, TIAN W J, et al. Leaching of valuable metals from red mud via batch and continuous processes by using fungi[J]. Miner Eng,2015, 81:1-4. [18] LU F H, XIAO T F, LIN J, et al. Recovery of gallium from Bayer red mud through acidic-leaching-ion-exchange process under normal atmospheric pressure[J]. Hydrometallurgy, 2018,175:124-132. [19] SCRIBOT C, MAHERZI W, BENZERZOUR M, et al. A laboratory-scale experimental investigation on the reuse of a modified red mud in ceramic materials production[J]. Construction and Building Materials, 2018,163:21-31. [20] LU F H, XIAO T F, LIN J, et al. Resources and extraction of gallium:a review[J]. Hydrometallurgy, 2017,174:105-115. [21] DEIHIMI N, IRANNAJAD M, REZAI B. Characterization studies of red mud modification processes as adsorbent for enhancing ferricyanide removal[J]. J Environ Manage, 2017,206:266-275. [22] LU F H, XIAO T F, LIN J, et al. Recovery of gallium from Bayer red mud through acidic-leaching-ion-exchange process under normal atmospheric pressure, Hydrometallurgy,2018,175:124-132. [23] LU F H, SU X D, HUANG F, et al. Co-treatment of spent pot-lining and red mud for carbon reutilization and recovery of iron, aluminum and sodium by reductive sintering process[J]. Metall Mater Trans B, 2020,51:1564-1575. [24] LEHOUX A, LOCKWOO C, MAYES W, et al. Gypsum addition to soils contaminated by red mud:implications for aluminium, arsenic, molybdenum and vanadium solubility[J]. Environmental Geochemistry and Health, 2013, 35:643-656. [25] KONG X, LI M, XUE S, et al. Acid transformation of bauxite residue:conversion of its alkaline characteristics, Journal of Hazardous Materials, 2017, 324:382-390. [26] XUE S, LI M, JIANG J, et al. Phosphogypsum stabilization of bauxite residue:conversion of its alkaline characteristics[J]. Journal of Environmental Sciences, 2019, 77:4-13. [27] HE H W, HAO L F, FAN C G, et al. A two-step approach to phosphogypsum decomposition:oxidation of CaS with CO2[J]. Thermochim. Acta, 2022, 708:179122. [28] MA L, NING P, ZHENG S. Reaction mechanism and kinetic analysis of the decomposition of phosphogypsum via a solid-state reaction[J]. Industrial & Engineering Chemistry Research, 2010(8),49:3597-3602. [29] 毕诗文.氧化铝生产工艺[M]. 北京:化学工业出版社, 2006. [30] LI X B, XIAO W, LIU W, et al. Recovery of alumina and ferric oxide from Bayer red mud rich in iron by reduction sintering[J].Trans Nonferrous Met Soc China, 2009, 19(5):1342-1347.
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