Swelling related to ettringite crystal formation in chromite ore processing residue

Several million tons of Chromite Ore Processing Residue (COPR) were deposited at two sites in New Jersey and Maryland, USA, and over time they exhibited extensive heaving phenomena. Ettringite, a needle-shaped mineral and an expansive mineral commonly recognized in the literature concerning cement- and soil, has been identified extensively in numerous COPR samples collected from these sites. It was therefore believed that ettringite formation and its crystal growth are strongly associated with COPR heaving. We investigated the correlation between ettringite and the heaving phenomena in COPR materials that contained no initial ettringite. Two identical COPR samples were exposed to a 4% w/w sulfate solution (25°C, 50°C) in a confined swell test apparatus. Both swell test samples were analyzed by means of X-ray powder diffraction. The peak intensities of newly formed ettringite were more pronounced in the sample tested at 50°C, and swell development was only observed in this sample. Scanning electron microscopy analyses revealed well-crystallized ettringite needles exceeding 40 μm in length for this sample, while ettringite crystals less than 15 μm in length formed in the sample tested at 25°C. Therefore, the results suggest that the quantity of ettringite and the extent of crystallization play a key role in the heave of COPR.     

固硫型煤渣烧制水泥熟料的研究初探

发展固硫型煤工业是治理煤烟型大气污染及减少二氧化硫对大气污染的有效途径。燃烧固硫型煤将产生大量固硫煤渣,对环境构成新的威胁。本文从实验探索的角度,研究开发利用固硫渣的途径。实验中对固硫渣做了化学全分析,用Ｘ－射线粉末衍射法（ＸＲＰＤ）对固硫渣及其加入一定量的添加剂后的煅烧产物进行物相鉴定,证实在一定的条件下固硫渣可以烧制成硫铝酸盐水泥熟料     

Fe-Si添加剂对型煤燃烧固硫的促进作用

为提高型煤燃烧固硫效率,用微量Ｆｅ－Ｓｉ氧化物作为固硫促进剂加入钙碱吸收占,经１２００℃以上高温燃烧后进行固硫率计算,其固硫率可达６５％。用炉渣产物用Ｘ射线粉末衍射法进行物相鉴定,发现生成一种热稳定化合物ＣａＦｅ３（ＳｉＯ４）２ＯＨ,实验证明其有利于型煤燃烧固率的提高．     

型煤燃烧过程中CaS的形成及其固硫作用

本文研究了不同温度和燃烧条件下Ｆｅ－Ｓｉ体系钙基固硫剂的作用效果,实验表明,煤粒子子直接进入已达一定的温度的炉内时,其固硫效果较在程序升温条件下明显提高,在１３００℃高温仍肌７７％的固硫率,含硫物相以ＣａＳ为主,该条件下造成了煤粒子的缺陷氧燃烧,由此造成的局部还原气氛促了ＣａＳ为主。从而提高固硫率,Ｃａ可能是高温条件的理想固硫产物。     

型煤高温固硫终产物Ca－Fe－S－Si－O体系的表征

当型煤中适当加入添加剂硅,铁组分燃烧生成新的Ｃａ－Ｆｅ－Ｓ－Ｓｉ－Ｏ体系后,固硫率明显提高,本文用Ｘ射线粉末衍射法与Ｘ射线荧光光谱法对该体系的高温固硫终产物进行产征,分析了灰渣样品并讨论添加剂对固硫率的影响,为型煤工业配料寻求可靠依据。     

大气降尘中水溶性有机物组成与含量的研究

本文为了研究各个地区大气降尘中水溶性有机物的组成与含量,从离地表２０ 米处的电网绝缘子表面采集九个大气降尘样品,对其水溶性部分用有机溶剂进行有机物的分离萃取,求出有机物的含量,采用ＸＲＰＤ 进行物相鉴定,确定有机物的组成可分为有机酸、有机酸钾盐、有机碱·盐酸盐加合物,尿素与尿素·硝酸盐加合物等四类,并对其影响ＣａＳＯ４·２Ｈ２Ｏ 的溶解度进行一系列实验,结果表明这四类有机物对ＣａＳＯ４·２Ｈ２Ｏ 溶解度的提高均有显著影响,可提高４０ ％ － ６０ ％ ,与实际降尘样品中其溶解度平均提高５０ ％ 左右相一致。由于大气降尘中普遍存在来自土壤与燃煤飞灰所排放的ＣａＳＯ４·２Ｈ２Ｏ,研究有机物的组成与含量,这对了解局部地区环境酸化（ 湿沉降） 有其重要性。     

型煤高温固硫终产物Ca－Fe－S－Si－O体系的表征

当型煤中适当加人添加剂硅、铁组分燃烧生成新的Ｃａ－Ｆｅ－Ｓ－Ｓｉ－Ｏ体系后，固硫率明显提高。本文用Ｘ射线粉末衍射法与Ｘ射线荧光光谱法对该体系的高温固硫终产物进行表征；分析了灰渣样品并讨论添加剂对固硫率的影响，为型煤工业配料寻求可靠依据。