Use of waste gypsum to replace natural gypsum as set retarders in portland cement

The present study is focused on clarifying the influence of waste gypsum (WG) in replacing natural gypsum (NG) in the production of ordinary Portland cement (OPC). WG taken from slip casting moulds in a ceramic factory was formed from the hydration of plaster of paris. Clinker and 3–5 wt% of WG was ground in a laboratory ball mill to produce cement waste gypsum (CMWG). The same procedure was repeated with NG to substitute WG to prepare cement natural gypsum (CMNG). The properties of NG and WG were investigated via X-ray Diffraction (XRD), X-ray fluorescence (XRF) and differential scanning calorimetry (DSC)/thermogravimetric (TG) to evaluate the properties of CMNG and CMWG. The mechanical properties of cement were tested in terms of setting time, flexural and compressive strength. The XRD result of NG revealed the presence of dihydrate while WG contained dihydrate and hemihydrate. The content of dihydrate and hemihydrates were obtained via DSC/TG, and the results showed that WG and NG contained 12.45% and 1.61% of hemihydrate, respectively. Furthermore, CMWG was found to set faster than CMNG, an average of 15.29% and 13.67% faster for the initial and final setting times, respectively. This was due to the presence of hemihydrate in WG. However, the values obtained for flexural and compressive strength were relatively the same for CMNG and CMWG. Therefore, this result provides evidence that WG can be used as an alternative material to NG in the production of OPC.     

石灰石/石膏湿法烟气脱硫的化学过程研究

以石灰石／石膏湿法烟气脱硫工艺为对象，针对SO2倍除的物理，化学过程进行了系统地分析研究，并在此基础上全面地阐述了该法脱除SO2的机理，为深入研究并在工程实施中合理应用提供参考。     

Use of FGD gypsum in fire resistant panels

Gypsum from power plant flue gas desulphurization units (FGD gypsum) is a combustion by-product produced in high quantities. In this paper, gypsum panels composed of 100% FGD gypsum from two power plants have been subjected to different physico-chemical (density, pH, humidity), mechanical (flexural and compressive strength, surface hardness, impact resistance), fire resistance and environmental tests (leaching and radioactivity). The results obtained have been compared with the requirements established in some European standards for commercial gypsum and other standards for similar products. In addition, the panels manufactured have been compared with commercial gypsum panels in order to determine the recycling possibilities of this kind of material in this application.     

瑞明电厂石灰石/石膏湿法脱硫技术分析

主要介绍了瑞明电厂石灰石／石膏湿法烟气脱硫(FGD)系统的主要设计参数及其工艺流程，并对调试和运行中发现的一些问题进行了分析和讨论。     

脱硫石膏气流烘干工艺的改进

介绍了脱硫石膏气流烘干改进工艺，该工艺可以解决烘干筒内水分聚集影响烘干效果和浪费燃料的问题。     

A novel method for preparing phosphorus building gypsum (PBG)-based building materials with low water/gypsum ratios

Journal of Material Cycles and Waste Management - It is necessary to consider the dual problems of poor performance and low production efficiency that stem from the highly utilised water/gypsum...     

柠檬酸废渣石膏综合利用研究进展及前景展望

柠檬酸废渣石膏主要由二水石膏组成，化学成分与天然石膏相近，只要工艺合理，就可以实现柠檬酸废渣石膏的资源化利用。综述了柠檬酸废渣石膏生产石膏粉、石膏砌块和石膏板材，用于硫铝酸盐水泥生产，用作水泥缓凝剂、制备晶须等方面的研究进展；提出了柠檬酸废渣石膏在生产粉笔、用于水泥矿化剂和与石英尾砂等工业废渣联合使用等方面的应用前景。     

氟石膏制备粉刷石膏技术研究

以氟化盐厂排放的工业废渣氟石膏为原料,通过实验研究了氟石膏物理性质及激发剂对其性能的影响.并以此为基材,添加水泥、生石灰等其他外加剂研制出氟石膏干混粉刷石膏砂浆,该抹面材料各项指标达到国家标准,具有良好的施工性能,开辟了氟石膏资源利用新途径.     

石灰石/石膏湿法脱硫系统单耗分析及节能方向

建立了石灰石/石膏湿法烟气脱硫系统单耗分析模型,以三河电厂350MW机组为例,分析了脱硫系统单耗在各设备及系统的分布情况,探讨湿法烟气脱硫系统的节能方向。     

Measuring the gypsum content of C&D debris fines

Construction and demolition (C&D) debris recycling facilities often produce a screened material intended for use as alternative daily cover (ADC) at active landfills or for shaping and grading at closed landfills. This product contains soil and small pieces of wood, concrete, gypsum drywall, shingles and other components of C&D debris. Concerns have been raised over the contribution of gypsum drywall in C&D debris fines to odor problems at landfills where the product is used. To address such concerns, limitations may be placed on the percentage of gypsum (or sulfate) that can occur, and standardized testing procedures are required to permit valid compliance testing. A test procedure was developed for measuring the gypsum content in C&D debris fines. The concentration of sulfate leached in an aqueous solution was used to estimate the initial gypsum content of the sample. The impact of sample size and leaching time were evaluated. Precision and accuracy increased with increasing gypsum content. Results from replicate samples had an average relative standard deviation of 9%. The gypsum content of fines obtained from different facilities in the US varied widely from 1% to over 25%. These variations not only occurred between differing facilities, but within batches produced within a single facility.     

脱硫石膏综合利用的现状与展望

介绍了国内外脱硫石膏在农业、水泥行业、建材行业和其他方面的综合利用情况,以及脱硫石膏分解技术的研究现状,探讨了分解温度、反应气氛和催化成分等因素对脱硫石膏分解效果的影响,展望了脱硫石膏的应用前景。指出:寻找脱硫石膏综合利用的新途径、找出适合脱硫石膏还原分解的气氛及其分解规律、探索有利于脱硫石膏还原分解的条件,是我国脱硫石膏实现循环利用的必经之路。     

石灰石-石膏湿法脱硫废水再处理方法探讨

石灰石-石膏湿法脱硫工艺进行烟气脱硫过程产生了脱硫废水，脱硫废水经常规工艺处理之后，水质有了改善，但未彻底治污，有必要进行再处理。介绍了目前正在采用的几种脱硫废水再处理的方法，并分析了其优缺点。     

脱硫石膏品质影响因素及其资源化利用

通过对石膏生成过程的分析,得出了影响石膏品质的主要因素,并且对改善石膏品质提出了建议.在此基础上,分析了脱硫石膏和天然石膏的成分,说明脱硫石膏的可利用性,并结合国内外的相关资料,介绍了脱硫石膏在工业、农业上的一些用途.     

脱硫石膏液相法生产高强度α-石膏的工艺研究

脱硫石膏是火电厂烟气脱硫副产物,由于其粒径较细、颗粒分配不均,煅烧生产比天然石膏困难,而液相法工艺适合脱硫石膏生产高强度α-石膏。对脱硫石膏液相法生产高强度α-石膏的工艺参数进行了研究,通过对反应转晶剂添加量、转化温度、压力及反应时间等参数调整,得到了脱硫石膏生产的合理参数。     

脱硫石膏干燥过程中的粘壁原因及其解决方案

分析了脱硫石膏在回转圆筒干燥机内粘壁的原因，并通过大量的试验，找出了引起粘壁的关键因素，在此基础上提出了避免粘壁的解决方案。     

湿法脱硫石膏弃浆与煤灰浆混合排放试验研究

通过华能珞璜电厂现场水质测试和实验室模拟生垢试验研究，认为该厂脱硫石膏浆与煤灰浆混合后的结垢成分以氢氧化镁为主，将脱硫弃浆引入水力输灰系统将可大大降低输灰管的结垢速率。     

脱硫石膏综合利用现状及其抹面材料的研制

概述了目前有关脱硫石膏性能及其利用的研究现状,研究开发了建筑用脱硫石膏抹面材料,此种材料经性能检测,其抗压强度、抗折强度分别达到 4.5 MPa、 17.5 MPa,且粘结性能优良,为脱硫石膏的再生利用提供了另外一条有效的途径.     

石灰石-石膏湿法烟气脱硫装置的防腐蚀

主要介绍了华能珞璜电厂 4× 36 0MW机组石灰石 -石膏湿法烟气脱硫装置的内衬防腐技术及防腐蚀效果。通过对装置的运行考核 ,分析鳞片树脂衬里防腐蚀的对症性和可靠性     

电厂烟气脱硫副产物石膏的循环利用

简述了国内烟气脱硫石膏的应用现状及存在问题,提出了烟气脱硫石膏加工向多品种、深层次、高附加值转移的思路.借鉴国外先进生产技术和设备,开发具有自主知识产权的石膏加工设备,实现国产石膏深加工设备的重大突破,有效地解决脱硫石膏的应用问题,实现循环经济和资源可持续发展.