Journal of University of Science and Technology Beijing
Volume 13, Number 6, December 2006, Page 1
Corresponding author: Huanjian Li, E-mail: lihuajian03@mails.tsinghua.edu.cn
Dissolution properties of calcined gangue
Huajian Li
1)
, Henghu Sun
1)
, Xuchu Tie
2)
, and Xuejun Xiao
2)
1) Department of Material Science and Engineering, Tsinghua University, Beijing 100084, China
2) Deportment of Resources, China University of Mining & Technology (Beijing), Beijing 100083, China
(Received 2006-02-12)
Abstract: In order to study the dissolution mechanism of gangue, Si and Al ions dissolving-out characteristics of the gangue samples
calcined at different temperatures in alkaline solutions and alkali metal silicate solutions were analyzed by identical coupled plasma
optical emission spectroscopy (ICP). The results show that the dissolution extent of Al and Si varies with different calcination tem-
peratures. It shows that the samples have a higher dissolution extent in NaOH than in KOH medium. Si and Al appear to have syn-
chro-dissolution behavior in alkaline solution, which means that Si and Al could dissolve from the mineral surface in some linked
forms. The result that a higher dissolution extent in sodium silicate solution and a lower dissolution extent in sodium-potassium sili-
cate solution of Al is proved by the 29Si NMR spectra and the mean connectivity degree of these alkali metal silicate solutions.
Key words: calcined gangue; dissolution property; identical coupled plasma optical emission spectroscopy (ICP); NMR
[This work was financially supported by the National Natural Science Foundation of China (No.50474002) and the Key Project of
Ministry of Education of China (No.104231).]
1. Introduction
The amount of gangue in China has already cumu-
lated to 3.8 billion tons, moreover, the stockpile of
gangue is increasing at a rate of 0.2 billion tons per
year [1]. A research on alumino-silicate wastes such as
gangue is important for the large-scale utilization of
wastes. The dissolution of active aluminum and sili-
con is thought as the activity source of alumi-
no-silicate minerals. A lot of researches on the ion
dissolution of alumino-silicate minerals have been
done around the world [2-3] and the mechanism of ion
dissolution of alumino-silicate minerals has been put
forward [4-5]. Gangue is used to produce the alumi-
nosilicate based cementitious materials due to its
chemical composition and mineral structure
[6-7]. The
goal of this research on the ion dissolution properties
of calcined gangue is to uncover the activity property
and the mechanism of activity exertion. There are
many researches on the ion dissolution property of
calcined gangue in concentrated alkaline solution
[8],
however, few researches focus on the ion dissolution
property of calcined gangue in different silicate solu-
tions. In this paper, ion dissolution properties of gan-
gue and calcined gangue both in concentrated alkaline
solutions and different silicate solutions were studied
to attain the best activity exertion mechanism of gan-
gue.
2. Raw materials and experiment
2.1. Raw materials
The raw materials include gangue (from Ji’an,
Jiangxi Province), industrial sodium silicate solution
(mass fraction: 45wt%; the molecular ratio of
SiO
2
/R
2
O: 2.60), NaOH and KOH (analytical reagent).
The chemical composition of gangue analyzed by
X-ray fluorescence (XRF-1700) is listed in Table 1.
Table 1. Chemical composition of gangue wt%
2.2. Experimental
X-ray diffractograms (XRD) were recorded on a
Rigaku D/max-R spectrometer using Cu K
α
radiation
(40 kV, 100 mA) with a scanning rate of 4/min from
5 to 70. The infrared spectroscopy was determined