盐溶液法制备半水石膏的工艺研究及探讨

屈吉艳; 陈高祥; 刘芮村; 周勇; 罗建洪

doi:10.3969/j.issn.1000-6532.2024.03.005

盐溶液法制备半水石膏的工艺研究及探讨

四川大学化学工程学院，四川　成都　610065

基金项目: 国家自然科学基金项目(21776181)；国家重点研发计划项目(2018YFC1900203-03)；四川大学创新星火计划项目(2018SCUH0012)

详细信息

作者简介: 屈吉艳（1996-），女，在读研究生，研究方向为冶金工程

通讯作者: 罗健洪（1978-），男，副教授，主要从事微通道萃取、结晶分离与纯化技术开发、含重金属废水处理技术开发。

中图分类号: TD98; X754

收稿日期: 2022-08-18

刊出日期: 2024-06-25

Study and Discussion on Preparation of Hemihydrate Gypsum by Salt Solution Method

Department of Chemical Engineering, Sichuan University, Chengdu 610065, Sichuan, China

More Information

Corresponding author: LUO Jianhong, luojianhong@scu.edu.cn

Received Date: 18 August 2022

Publish Date: 25 June 2024

摘要

摘要:
这是一篇矿物材料领域的论文。利用脱硫石膏制备应用更为广泛的半水石膏对工业副产石膏的资源化利用有非常重要的作用，不仅可以避免对天然石膏的大量开采，还能实现对脱硫石膏的资源化利用。在脱硫石膏转化为半水石膏的过程中，以氯化钠和添加剂作为反应溶液，在常压下加热搅拌反应。研究了氯化钠浓度、添加剂浓度、固液比、转速和反应温度等因素对二水到半水石膏的相转化时间和晶体粒度的影响，氯化钠和添加剂浓度的增大，不仅会加快相转化过程，还对半水石膏晶体的平均长度和平均长径比有一定的抑制作用，而较高或较低的转速则会阻碍半水石膏晶体的成核和生长，过快或过慢的转速都会影响Ca²⁺和SO₄^2-的碰撞频率，继而影响半水石膏的生成。降低固液比和升高温度也对相转化过程有一定的促进作用，在较低的温度下，由于相转化过程的驱动力不足，脱硫石膏难以转化为半水石膏。确定了脱硫石膏制备半水石膏的较佳工艺条件为：氯化钠浓度10%，添加剂浓度10%，固液比1:5，转速300 r/min，反应温度100 ℃。在较佳的工艺条件下，60 min即可完成反应。所制得的半水石膏晶体的平均长度高达127 μm，平均长径比高达19。同时，研究了溶液中水分子活度、过饱和度和反应温度的关系，确定了相转化过程由温度和过饱和度所决定。
- 矿物材料 /
- 脱硫石膏 /
- 半水石膏 /
- 氯化钠 /
- 粒径分析
Abstract:
This is an article in the field of mineral materials. The utilization of desulfurized gypsum (FGD) to prepare more widely used hemihydrate gypsum plays a very important role in the resource utilization of industrial by-product gypsum. It can not only avoid the large-scale exploitation of natural gypsum, but also realize the resource utilization of desulfurized gypsum. In the process of converting FGD gypsum into hemihydrate gypsum, appropriate concentration of additive and sodium chloride were used as the reaction solution, and the process was heated and stirred under normal pressure. The effects of sodium chloride concentration, additive concentration, solid-liquid ratio, rotation speed and reaction temperature on the phase conversion time and crystal size of dihydrate to hemihydrate gypsum were studied. The increase of additive and sodium chloride concentration not only sped up the phase conversion process but also had a certain inhibitory effect on the average length and average aspect ratio of hemihydrate gypsum crystals. Higher or lower rotation speed hindered the nucleation and growth of hemihydrate gypsum crystals and affected the collision frequency of Ca²⁺ and SO₄^2- in the NaCl added solution, thus delaying the formation of hemihydrate gypsum. Decreasing the solid-liquid ratio and increasing the temperature had a certain promoting effect on the phase conversion process. At a lower temperature, due to the insufficient driving force of the phase conversion process, it was difficult to transform FGD gypsum into hemihydrate gypsum. The optimal process conditions for preparing hemihydrate gypsum from FGD gypsum were determined as follows: sodium chloride concentration 10%, additive concentration 10%, solid-liquid ratio 1∶5, rotating speed 300 r/min, reaction temperature 100 ℃. Under the best process conditions, the reaction could be completed in 60 min. The average length of the prepared hemihydrate gypsum crystals was as high as 127 μm, and the average aspect ratio was as high as 19. At the same time, the relationship between the activity of water molecules in the solution, the degree of supersaturation and the reaction temperature was studied, and it was determined that the phase conversion process was determined by the temperature and the degree of supersaturation.
- Mineral materials /
- Desulfurization gypsum /
- Hemihydrate gypsum /
- Sodium chloride /
- Particle size analysis

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图 1 预处理后脱硫石膏的XRD

Figure 1.

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图 2 预处理后脱硫石膏的SEM

Figure 2.

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图 3 氯化钠浓度对反应时间的影响

Figure 3.

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图 4 氯化钠浓度对半水石膏平均长度、宽度和长径比的影响

Figure 4.

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图 5 添加剂浓度对反应时间的影响

Figure 5.

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图 6 添加剂浓度对半水石膏平均长度、宽度和长径比的影响

Figure 6.

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图 7 固液比对反应时间的影响

Figure 7.

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图 8 固液比对半水石膏平均长度、宽度和长径比的影响

Figure 8.

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图 9 转速对反应时间的影响

Figure 9.

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图 10 反应温度对反应时间的影响

Figure 10.

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图 11 无水、半水和二水石膏在0～150 ℃的溶解度曲线

Figure 11.

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图 12 二水石膏向半水石膏的转化过程

Figure 12.

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图 13 半水石膏的SEM

Figure 13.

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图 14 半水石膏的XRD

Figure 14.

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图 15 半水石膏的FTIR

Figure 15.

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图 16 水分子活度与温度的关系

Figure 16.

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图 17 100 ℃下过饱和度与水分子活度的关系

Figure 17.

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表 1 预处理后脱硫石膏的化学组成/%

Table 1. Chemical composition of pretreated FGD gypsum

CaO	SO₃	H₂O	Fe₂O₃	Al₂O₃	MgO	其他
36.20	42.80	20.34	0.14	0.39	0.09	0.04

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表 2 不同工艺条件下的结晶水含量

Table 2. Content of crystal water under different conditions

添加剂浓度/%	氯化钠浓度/%	固液比	转速/ (r/min)	温度/ ℃	结晶水含量/%
0	10	1∶5	300	100	16.55
0	11	1∶5	300	100	6.86
0	12	1∶5	300	100	5.60
0	13	1∶5	300	100	6.42
0	14	1∶5	300	100	6.81
6	10	1∶5	300	100	6.42
8	10	1∶5	300	100	6.55
10	10	1∶5	300	100	5.32
12	10	1∶5	300	100	6.11
14	10	1∶5	300	100	5.64
10	8	1∶5	300	100	6.05
10	9	1∶5	300	100	5.60
10	10	1∶5	300	100	5.32
10	11	1∶5	300	100	5.57
10	12	1∶5	300	100	5.48
10	10	1∶3	300	100	6.54
10	10	1∶4	300	100	5.82
10	10	1∶5	300	100	5.32
10	10	1∶6	300	100	6.22
10	10	1∶7	300	100	6.27
10	10	1∶5	200	100	5.52
10	10	1∶5	300	100	5.32
10	10	1∶5	400	100	6.05
10	10	1∶5	500	100	6.31
10	10	1∶5	600	100	5.54
10	10	1∶5	300	94	16.38
10	10	1∶5	300	96	6.34
10	10	1∶5	300	98	5.50
10	10	1∶5	300	100	5.32
10	10	1∶5	300	102	6.17

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