贵州某高岭土除铁试验研究

贵州某硬质高岭土矿石中铁含量较高,不能直接利用,必须进行除铁。针对高岭土矿石中铁矿物主要为黄铁矿和弱磁性氧化铁矿物,且其嵌布粒度极细的特点,开展了浮选除铁、强磁选除铁探索试验。并在此基础上进行了强磁-酸浸及强磁-氧化酸浸试验。结果表明,采用强磁选-氧化酸浸的方法效果较好,可将高岭土中的Fe含量由1.44%降到0.75%。     

Catalytic dehydration of lactic acid to acrylic acid over sulfate catalysts

The production of acrylates from biomass‐originated lactic acid is of extraordinary importance to overcome the increasing worldwide shortage of petroleum. In this work, the catalytic dehydration of lactic acid to acrylic acid was carried out over calcium sulfate catalyst with cupric sulfate and phosphates as promoters. The mass ratio of m(CaSO₄)/m(CuSO₄)/m(Na₂HPO₄)/m(KH₂PO₄) is 150.0:13.8:2.5:1.2. In the dehydration of lactic acid, effects of carrier gas, calcination temperature for catalyst, concentration of lactic acid as well as contact time are discussed in detail. With carbon dioxide as carrier gas, the highest acrylic acid yield of 63.7% is achieved from 26 wt.% lactic acid at 330°C and 88 s contact time.     

煅烧凹凸棒石的水化处理对其结构演化和吸附NH3的影响

采用X射线衍射分析了煅烧凹凸棒石的水化处理对其结构演化的影响;通过NH3吸附试验表征煅烧凹凸棒石水化处理后表面性质的变化,揭示了凹凸棒石对NH3的吸附机理。结果表明：随着煅烧温度的不断提高,凹凸棒石中的结晶水和结构水逐步脱除,内孔道结构发生折叠塌陷,凹凸棒石的内孔道折叠温度在250～300℃之间,只有低于300℃煅烧的...     

Dynamic modeling of a multiple hearth furnace for kaolin calcination

A dynamic model of a multiple hearth kaolin calciner has been developed and is presented in this article. This model describes the physical‐chemical phenomena taking place in the six furnace parts: the solid phase, gas phase, walls, cooling air, rabble arms, and the central shaft. The solid phase movement, in particular, is described by a novel mixing model. The mixing model divides the solid bed in a hearth into volumes and the distribution of their contents, after one full central shaft rotation, is identified by the pilot experiments. First, the model is validated by the industrial data, and then the dynamics of the multiple hearth furnace is studied by introducing step changes to the three manipulated variables: the feed rate, and the gas, and air flows supplied. The responses of the gas phase temperature and solid bed component profiles are analysed and the results are discussed. © 2015 American Institute of Chemical Engineers AIChE J, 61: 3683–3698, 2015     

高岭土除铁技术进展

高岭土是以高岭石族矿物为主的黏土岩类矿产,广泛应用于陶瓷、造纸和涂料等行业。高岭土的白度和含铁量是决定其应用价值的重要指标之一。研究高岭土中铁的赋存状态和除铁增白技术就显得尤为重要。     

微生物絮凝剂的絮凝特性研究

从活性污泥中分离出1株产高效絮凝剂微生物AspergillusM-25,利用其发酵液进行絮凝特性实验。实验结果表明:(1)该絮凝剂对250μm,4g/L,pH为7的高岭土悬浊液有良好的絮凝效果,絮凝率>97%;(2)菌株M-25产生的活性成分95%存在于上清液中,只有约5%存在于洗涤后的菌细胞中,未接种的培养液中不含絮凝成分;⑶影响生物絮凝剂絮凝效果的因素主要有絮凝剂的投加量,高岭土悬浊液的pH、浊度、粒度以及金属离子的添加;⑷利用该生物絮凝剂处理活性炭粉末溶液和土壤悬浊液,也取得较好的处理效果,显示了絮凝范围的广泛性。     

煅烧温度对天然水硬石灰物理力学特性影响研究

研究了900～1150℃煅烧温度对寒武纪灰岩制备的天然水硬石灰物理力学特性的影响.利用XRD谱、SEM照片和消化速率表征煅烧产物特性,风吹成粉后检测天然水硬石灰凝结时间和抗折抗压强度.研究表明900～1150℃煅烧温度范围内,煅烧产物主要成分均为游离CaO和β-Ca2 SiO4,28 d抗压强度均达到天然水硬石灰NHL...     

O2/CO2气氛下水蒸气对石灰石同时煅烧/硫化的影响

为进一步探讨富氧气氛下水分对硫化特性的影响,利用等温热重实验装置,进行了富氧燃烧石灰石同时煅烧/硫化实验,研究了水蒸气浓度、温度、石灰石粒径以及种类等对石灰石同时煅烧/硫化特性的影响。水蒸气提高了石灰石煅烧速率,石灰石完全分解时间缩短;在硫化反应动力学控制阶段水蒸气的影响不明显,而到扩散控制阶段促进作用变得显著。富氧气氛下水蒸气的影响随温度（实验范围）升高而突出,温度越高最终的钙转化率越高。粒径效应显著,随石灰石粒径的减小最终钙转化率明显提高。水蒸气对不同种类石灰石的同时煅烧/硫化特性影响趋势基本一致。     

以焙烧高岭土为原料合成ZSM-5分子筛

以焙烧高岭土为原料,采用水热法合成ZSM-5分子筛,考察了晶化温度、晶化时间、模板剂用量以及投料硅铝比等因素对分子筛合成的影响,得出了最佳的合成条件：晶化温度为140～160℃,晶化时间为24h, n(TPAOH)/n(SiO2)=0.10,投料硅铝比为15:1。采用XRD,SEM,N2 吸附脱附等手段对最佳条件下所合成的样品进行表征,结果表明,以焙烧高岭土为原料可以合成出结晶度相对较高、微孔分布集中于0.56 nm、晶粒大小约2μm的小颗粒ZSM-5分子筛。     

加碱煅烧活化粉煤灰工艺参数研究

研究了以碳酸钠为助剂活化粉煤灰的煅烧工艺。采用滴定法测定不同煅烧条件（煅烧温度和煅烧时间）所得活化粉煤灰溶解在氢氧化钠溶液中的硅、铝浓度,并采用X射线衍射（XRD）表征不同煅烧条件（灰碱质量比）所得活化粉煤灰的物相组成,得出粉煤灰较佳煅烧工艺参数：煅烧温度为875 ℃,保温时间为1.5 h,粉煤灰与碳酸钠的质量比为1∶0.87。煅烧后的产物主要以可溶性的硅铝酸钠（NaAlSiO₄）和硅酸钠（Na₂SiO₃）为主,原粉煤灰中的石英、莫来石基本消失,粉煤灰得到充分活化。