钛工业固废钛石膏胶凝性与强度机理分析

采用X射线衍射(XRD)、扫描电镜(SEM)、能谱分析(EDS)等方法研究钛石膏(TG)的胶凝性与强度机理。结果表明,110~250℃范围内,随着煅烧温度的升高,钛石膏的胶凝性呈先升高后趋于稳定的趋势。190℃煅烧2 h,钛石膏主要成分为CaSO_4·0.5H_2O,具有较好胶凝性。钛石膏中的CaMg(CO_3)_2和CaCO_3杂质来自石灰中和废硫酸过程。钛石膏试块强度较低的主要原因为:钛石膏标准稠度用水量较大,为98%,在自然养护过程中大量自由水蒸发,产生较多孔洞,密度较小,为0.9 g/cm~3,二水石膏晶体间搭接空隙较大;同时,钛石膏中的铁杂质以絮状Fe(OH)_3覆盖在CaSO_4·2H_2O晶体上,阻碍CaSO_4·2H_2O晶体的发育,导致二水石膏晶体强度较低。

Analysis on the Cementation and Strength Mechanism of Titanium Industry Solid Waste Titanium Gypsum

The gelation and strength mechanism of titanium gypsum(TG)were analyzed with XRD,SEM,EDS and other analytical methods.The results show that the gelling properties of TG rised and tended to be stable with the increase of calcination temperature at 110~250℃.The main component of TG calcined at 190℃for 2 hours is CaSO4·0.5H2O,which has good gelling properties.The impurities of CaMg(CO3)2 and CaCO3 in TG come from the process of neutralizing waste sulfuric acid with lime.The main reason for the lower strength of the TG test block is that the standard consistency of TG requires a lot of water(98%),and a large amount of free water evaporates during the natural curing process,resulting in numerous macro and micro-pores,and the density is small(0.9 g/cm3),the lap gap between dihydrate gypsum crystals is large.At the same time,the CaSO4·2H2O crystals are covered with flocculent Fe(OH)3 impurities in the TG,which hinder the development of the CaSO4·2H2O crystals,resulting in lower strength of the dihydrate gypsum crystals.