Properties and hydration mechanism of aluminum sulfate type alkali-free accelerator prepared from waste sulfuric acid from titanium dioxide production
DENG Lin1,2, MAO Xue-hua1
1. College of Biological and Chemical Engineering, Panzhihua University, Panzhihua 617000, China; 2. Sichuan Provincial Key Laboratory for Comprehensive Utilization of Vanadium and Titanium Resources, Panzhihua 617000, China
Abstract: Aluminum sulfate type fluorine-containing alkali-free accelerators are prepared by acid hydrolysis of Al(OH)3 with hydrofluoric acid and waste sulfuric acid from titanium dioxide production.The effect of different dosages of fluorine-containing alkali-free accelerator on the performance of cement paste is investigated.The composition and microstructure of cement hydration products after adding accelerator are analyzed by means of XRD and SEM.The hydration conceptual model is proposed to simulate the hydration reaction mechanism of fluorine-containing alkali-free accelerator.Results show that waste sulfuric acid combined with hydrofluoric acid can dissolve aluminum hydroxide better,and the addition of hydrofluoric acid is beneficial to increase the content of aluminum in accelerator,making the performance of the accelerator better,and the maximum mass fraction can reach 48%.The initial setting time and final setting time of cement matrix are 3.17 min and 5.33 min,respectively when the dosage of fluorine-containing alkali-free accelerator is 7%.The prepared fluorine-containing alkali-free accelerator meets the requirements of qualified products in GB/T 35159—2017 Flash Setting Admixtures for Shotcrete.The preparation technology provides a treatment method for the reuse of waste sulfuric acid.
邓林, 毛雪华. 工业钛白废酸制备硫酸铝型无碱速凝剂的性能及水化机理研究[J]. 现代化工, 2022, 42(11): 211-216.
DENG Lin, MAO Xue-hua. Properties and hydration mechanism of aluminum sulfate type alkali-free accelerator prepared from waste sulfuric acid from titanium dioxide production. Modern Chemical Industry, 2022, 42(11): 211-216.
 仲津男.缓释型聚羧酸减水剂的合成及性能研究[D].西安:西安理工大学, 2015.  Dinoia T P, Sandberg P J.Alkali-free shotcrete accelerator interactions with cement and admixtures[M].London:Taylor & Francis Group, 2004:137-144.  Xu Q, Stark J.Early hydration of ordinary Portland cement with an alkaline accelerator[J].Adv Cem Res, 2005, 17:1-8.  Taylor, Fw H.Cement chemistry[M].2nd ed.London:Thomas Telford, 1997.  Bati G.Hydration products of C3A, C3S and Portland cement in the presence of CaCO3[J].Cement and Concrete Research, 2000, 30:1073-1077.  Knapen E, Gemert D V.Cement hydration and microstructure formation in the presence of water-soluble polymers[J].Cement & Concrete Research, 2009, 39(1):6-13.  Minard H, Garrault S, Regnaud L, et al.Mechanisms and parameters controlling the tricalcium aluminate reactivity in the presence of gypsum[J].Cem Conc Res, 2007, 37:1418-1426.  Pourchet S, Regnaud L, Perez J P, et al.Early C3A hydration in the presence of different kinds of calcium sulfate[J].Cement & Concrete Research, 2009, 39(11):989-996.  Juilland P, Gallucci E, Flatt R, et al.Cement and concrete research dissolution theory applied to the induction period in alite hydration[J].Cem Concr Res, 2010, 40:831-844.  Taylor H, Taylor L, Taylor F W, et al.Cement chemistry[J].Chemistry for Engineers, 1998, 134:214-237.  Nicoleau L, Nonat A.A new view on the kinetics of tricalcium silicate hydration[J].Cement and Concrete Research, 2016, 86:1-11.  Bullard J W, Jennings H M, Livingston R A, et al.Mechanisms of cement hydration[J].Cement and Concrete Research, 2011, 41(12):1208-1223.  Renan, P, Salvador, et al.Early age hydration of cement pastes with alkaline and alkali-free accelerators for sprayed concrete[J].Construction & Building Materials, 2016, 111(15):386-398.