Impact of gypsum on flotation of scheelite and fluorite using sodium oleate as collector

ABSTRACT

In this study, effect of calcium and gypsum on scheelite and fluorite was investigated using sodium oleate as collector. Micro-flotation and contact angle results showed that the adsorption of calcium could inhibit the hydrophobicity of scheelite and fluorite. Moreover, sulfate could enhance the inhibition. FT-IR results showed that calcium could be priori precipitated into calcium oleate and adsorb on mineral surface. The adsorption of calcium could increase the scheelite potential to IEP, while it showed limited effect on fluorite potential. However, the interaction of calcium on scheelite and fluorite in gypsum solution was more complex than that in calcium solution.     

石膏转化制硫酸钾结晶动力学及结晶添加剂研究

研究了浓氨介质中石膏与氯化钾直接转化制硫酸钾的结晶动力学及结晶添加剂的作用效果。结果表明 ,硫酸钾在氨介质中的成核速率与晶体生长速率、悬浮密度、搅拌速率存在如下关联式 :B0 =5 .64 13×10 8G3.32 0 8Mt0 .0 559np0 .2 92 8。加入异丙醇、OP乳化剂及十二烷基苯磺酸钠等添加剂 ,可使硫酸钾结晶产品纯度提高 ,晶体形态整齐均匀     

Continuous precipitation of calcium sulfate dihydrate from waste sulfuric acid and lime

Precipitation of calcium sulfate dihydrate, gypsum, from (i) a pure sulfuric acid/lime suspension and (ii) a waste sulfuric acid/lime suspension in a continuous pilot plant in the temperature range from 40 °C to 80 °C was studied. It was observed that in the case of waste sulfuric acid with a high content of Mg²⁺ and Fe²⁺ ions, several hours after the beginning of the precipitation, partial dissolution of the product and modification of the crystals from needle‐ and plate‐like to agglomerated structures occurred. It is suggested that the secondary changes occur due to the increased concentration of Mg²⁺ and Fe²⁺ ions in the reactor. Below 60 °C, and above 70 °C plate‐like and needle‐like single crystals respectively were formed. The mean size (d₅₀) of the crystals was found to increase with increasing temperature and decrease with the initial concentration of lime. Gypsum produced between 70 °C and 80 °C is suitable for further processing for construction plaster. In a precipitation process with pure sulfuric acid only single perfect needle‐like crystals occurred. Copyright © 2005 Society of Chemical Industry     

膏盐岩地层地质特征与录井技术

石油勘探实践和研究结果表明，许多油气藏的形成都与膏盐岩地层有关，也常与膏盐岩地层伴生，成功钻穿膏盐岩地层是钻井难题之一，录井技术成为钻进安全监测、膏盐岩地层准确预报的重要手段。针对上述情况，介绍了膏盐岩地层的主要类型、沉积模式以及与油气的关系，归纳总结了膏盐岩地层的录井技术经验，包括：在随钻录井过程中熟悉地质设计与邻井资料；在没有预测钻遇膏盐岩地层的情况下，通过钻井液中Cl^-的变化判定是否钻遇膏盐岩地层；预计钻遇膏盐岩地层时，使用饱和盐水钻井液；钻遇膏盐岩地层后观察盐岩是否以岩屑形式返出；同时，把握膏盐岩地层的岩性、岩性组合、层位、顶底界和厚度是非常重要的。通过S1井实例分析，论述了在膏盐岩地层中钻进时，防卡、防漏是录井人员监测和预报的重点。     

快速评定砂浆配方对钢筋腐蚀的影响

用电化学方法测定砂浆试件中钢筋的极化电阻，并测定了砂浆的孔隙率，结果发现:砂浆的孔隙率、孔径分布与钢筋极化电阻大小有良好的对应关系。电化学方法能可靠、快速测定砂浆配合比、添加剂对钢筋腐蚀速度的影响。     

水泥膨胀珍珠岩砂浆的保温试验研究与应用

荆江分洪北闸加固工程２号护坦（斜面）混凝土的保温层采用了水泥膨胀珍珠岩砂浆，并对这种材料的保温效果进行了试验研究。试验表明：水泥膨胀珍珠岩砂浆降低最高温差，减小内表温差，缩小表温变幅和防止混凝土表面裂缝效果显著。在北闸２号护坦混凝土表面铺设１万平方米保温层，获得良好效果。     

Observation and Analysis of Gypsum Particleboard using SEM

The microstructures of gypsum board and gypsum particleboard were observed by SEM. The effects of retarder and waterproof agent on the shape and the average dimension of the gypsum crystal were discussed. The mechanism was investigated as well. Four typical instances, i e, the gypsum crystal shape, the gypsum combined with particles on the particles surface, the gypsum combined with particles on the wood cross section and the gypsum combined with particles inside the wood cell cavity were selected and observed. Furthermore, the agglomeration and cementation mechanism between gypsum and particle were studied.     

亚硫酸钙氧化为石膏的研究

进行了亚硫酸钙氧化为二水石膏的研究 ,考察了初始 p H值、反应温度、空塔气速、固含量和停留时间对氧化率的影响 ,给出了适宜的反应条件 .在这些条件下 ,氧化率达 96 %以上     

Properties of latex blends and its modified cement mortars

In this paper, the mechanical properties of three latex blends and the mechanical properties and chloride diffusivity of the latex-modified mortars are studied. The relationships between the properties of polymer films formed from latex blends and the properties of the latex blend-modified mortars are illustrated. The test results showed that the modified mortar with the blend of styrene-acrylic ester (SAE) and styrene-butadiene rubber (SBR) showed synergistic effect; especially the flexural strength of the SAE/SBR blend-modified mortars was about 20-40% higher than that of monolatex-modified mortars. However, the vinyl chloride-vinylidene chloride copolymer (PVDC)/SBR and PVDC/SAE blends-modified mortars showed antisynergistic effect. The compressive strength of the modified mortars increased with the increasing of the tensile strength of the latex films, while the flexural strength of the modified mortars did not depend on the tensile strength of the latex films. When PVDC with the mass fraction of 0.2 or SAE copolymer emulsion with mass fraction of 0.4 was blended into SBR latex, the latex blend-modified mortars showed lower chloride diffusivity. The chloride diffusivity of the modified mortars increased approximately linear with the tensile strength of the latex blend films, and decreased with increase of the elongation at rupture of the latex blend films. When the elongation at rupture of the latex blend films increased from 200-300% to more than 800%, the chloride diffusivity of the modified mortars decreased from 10-15×10⁻¹² to 3-4×10⁻¹² m²/s.     

泥炭土地基钻孔漏浆的处理

以云南鸡石一级公路青鱼湾大桥为例，介绍了在软弱地层中施工桥梁钻孔灌注桩遇孔壁开裂漏浆时的处理方法，经试验证明，取得了较好的技术经济效果。