氯化焙烧法制备无水氯化钙的工艺研究

研究了用氯化铵作为氯化剂氯化焙烧碳酸钙制备无水氯化钙的工艺条件,通过单因素实验考察了焙烧温度、物料配比、焙烧时间及物料装载厚度的影响,并用XRD对无水氯化钙进行了表征。结果表明氯化焙烧法制无水氯化钙的最佳工艺条件为：焙烧温度为450 ℃、焙烧时间为60 min、氯化铵与碳酸钙物料配比n（氯化铵）∶n（碳酸钙）=3∶1、物料装载厚度大于1 cm。此条件下碳酸钙的转化率为95.8%、焙烧产物氯化钙的质量分数为94.96%。用工业级原料焙烧时,选用粒径为10.5 μm的工业重钙与工业氯化铵焙烧120 min,碳酸钙的转化率为95.19%,无水氯化钙的质量分数为94.83%。     

牡蛎贝壳制备药用碳酸钙的工艺改进

以牡蛎贝壳为原料制备的牡蛎碳酸钙，可以广泛用于食品添加剂和药用补钙剂，其重金属含量是必须严格控制的指标之一。通过对不同生产工艺条件下牡蛎碳酸钙产品中铅含量的测定，研究并开发了一种降低产品中铅含量的有效方法，通过调整牡蛎贝壳焙烧工艺参数，确定焙烧温度为900℃、时间为6h的条件，可有效降低碳酸钙产品中铅含量，并使之达到国家药监局颁布的药用碳酸钙中铅的限量要求。     

利用钾长石矿泥制钾钙肥

试验研究了钾长石在以硫酸钙、碳酸钙等为添加剂的体系中生产可溶性钾的工艺条件.采用单因素实验法对物料粒度、配比、焙烧温度、时间、助剂种类及用量进行研究.结果表明,在钾长石矿泥、硫酸钙、碳酸钙物质的量比为1∶1∶18、焙烧时间为3h、焙烧温度为1050℃时,制出的钾钙肥可溶性钾含量为4.89％.在焙烧时间2h、焙烧温度为1000℃时,添加助剂硫酸钠3.0％,制出的钾钙肥可溶性钾含量为5.76％.     

钾长石混盐焙烧-浸出提钾过程研究

中国钾盐资源匮乏,而钾长石是一种重要的钾赋存形式。然而,钾长石的开发技术难度大、成本高,至今尚未实现工业化应用。为了解决钾长石开发利用过程中钾提取温度高、浸出率低等问题,该研究选取了贵州铜仁地区钾长石矿为研究对象,探究了钾长石-硫酸钠-碳酸钙混盐的焙烧-浸出过程,考察了钾长石-硫酸钠-碳酸钙的焙烧配比、焙烧温度、焙烧时间、浸取剂浓度等因素对钾长石中钾元素浸出率的影响。实验结果显示,在焙烧体系均匀混合、焙烧温度为800～900℃、焙烧时间为1 h、m（钾长石）∶m（硫酸钠）∶m（碳酸钙）为（1∶1∶6）～(1∶1∶8)条件下,以质量分数为5%NaOH溶液作为浸取液,钾的浸出率可高达99.79%。该研究提供了一条提高钾长石资源利用效率、解决钾盐资源供应问题的新途径,并为相关工业生产提供了有力的技术支持。     

纳米碳酸钙/PVC复合树脂中钙含量的分析

分别采用盐酸溶解法、盐酸滴定法和高温焙烧法,对自制合成的4％、5％、6％和8％的纳米碳酸钙/PVC复合树脂的钙含量进行了测试,并对4％、6％纳米碳酸钙/PVC复合树脂经过筛分后的每个筛孔的钙含量进行了分析.结果表明:①盐酸溶解法测定值偏高,盐酸滴定法测定值偏低,高温焙烧法较为准确;②纳米碳酸钙/PVC复合树脂粒径范围集...     

钾长石-硫酸钙-碳酸钙体系的热分解过程分析

对钾长石-硫酸钙-碳酸钙体系的热分解过程产物进行了研究.应用电子探针连续测定不同温度的焙烧产物,结果表明,热分解产物有新生矿物生成,在钾长石与硫酸钙添加量不变的条件下随着碳酸钙的增加,新生矿物连续定量分析得出热分解产物为C2S、K2SO4,XRD也同时验证了上述结果.探讨了该体系分解机理,从而为利用该体系焙烧生产钾肥提...     

粉煤灰焙烧活化过程中矿物质变化规律

为探究不同活化剂对粉煤灰活化作用机理,选取燃烧和气化2种工艺的粉煤灰,分别与碳酸钠、碳酸钙、硫酸铵和浓硫酸混合后焙烧活化,采用XRD分析焙烧活化后的矿物质变化规律,结果表明:燃烧灰中铝元素主要以莫来石形式存在,气化灰主要以透辉石形式存在,碳酸钠焙烧活化后主要形成霞石,最佳活化温度为1 000℃;碳酸钙焙烧活化后主要生成钙长石,最佳活化温度为1 300℃;硫酸铵焙烧活后主要形成硫酸铝铵,最佳活化温度为500℃,在550℃时硫酸铝铵分解生成硫酸铝,硫酸铵活化可生成含硫和含氮气体;硫酸焙烧活化后主要生成硫酸铝,最佳活化温度为400℃。活化过程中气化灰中的钙易形成硬石膏,提高活化剂硫酸铵和硫酸的用量。4种活化剂的活化温度依次为碳酸钙碳酸钠硫酸铵浓硫酸,因此活化温度低的浓硫酸活化法更具有发展前景。     

富硼渣钙化焙烧研究

采用钙化焙烧的方法,将富硼渣中玻璃态B2O3转化为晶态的硼酸盐,提高富硼渣中硼的化学反应活性。分别考察了碳酸钙用量、焙烧温度对富硼渣活性的影响。实验结果表明:在950℃下,30 g富硼渣中加入18 g碳酸钙恒温焙烧2 h,富硼渣的活性由50%上升到86%。热力学计算和XRD物相分析表明,CaO与玻璃态B2O3反应生成晶态的Ca3(BO3)2是富硼渣化学反应活性提高的主要原因。     

影响聚合铁铝絮凝剂盐基度的因素

以氧化铝、碳酸钙、氯化铁为原料,制备了新型聚合铁铝絮凝剂(HF),并探讨了聚合过程中焙烧温度和酸溶时间等因素对絮凝剂盐基度的影响。通过实验得到其最佳合成条件:m(氧化铝)∶m(碳酸钙)=3∶2,酸溶时间为2h,m(铝酸钙)∶m(盐酸)=5∶19,焙烧温度为1200℃,FeCl3.6H2O的加入量为焙烧原料的12%。将该产品对化学预热机械浆(CTMP)废水做絮凝实验,得出保持45%左右的盐基度有最佳的絮凝性能。     

非金属矿加工专利文摘(国内)

一种利用碳酸盐型钡矿氯化焙烧制取氯化钡的方法 (ＣＮ1346 80 2Ａ)　将碳酸盐型钡矿在 5 0 0℃～ 15 0 0℃的温度下与氯化钙或氯化镁氯化焙烧生成氯化钡与碳酸钙或碳酸镁熔体 ,经过浸渣形成氯化钡溶液和固相的主要含碳酸钙或碳酸镁的渣子 ,再经固液分离 ,将氯化钡溶液通过浓缩、结晶、离心、干燥而制成氯化钡产品。本发明优点在于利用廉价工业氯化钙或氯化镁 ,一步法氯化焙烧、浸取制得。碳酸盐型钡矿中的主要杂质碳酸钙、二氧化硅、碳等不影响氯化钡收得率 ,氯根有效利用率高 ,所制得的氯化钡产品杂质含量少 ,成本低 ,工艺流程简单 ,基本…     

沉淀法制备纳米氧化锌的研究

通过实验和理论分析 ,对均匀沉淀法和直接沉淀法制备纳米氧化锌进行了比较 ,以硝酸锌为原料 ,尿素为均匀沉淀剂制得的氧化锌粒径小、分布窄、分散性好 ,远优于直接沉淀法制备的纳米氧化锌。     

不同制备方法对纳米氢氧化镁性能的影响

以六水氯化镁为原料,氢氧化钠为沉淀剂,分别采用正向沉淀法、反向沉淀法、双向沉淀法和超重力沉淀法制备了纳米氢氧化镁,以沉降速度为评价指标,考察了制备方法对氢氧化镁料浆沉降性能的影响.利用透射电子显微镜(TEM)、纳米激光粒度分布仪、X射线衍射仪(XRD)对产物的形貌、粒径、粒径分布和晶型进行表征.结果表明,采用超重力沉淀法,氢氧化镁料浆的沉降速度明显加快,分别是正向沉淀法、反向沉淀法、双向沉淀法的4.7倍、12.4倍、2.1倍;所得氢氧化镁的分散性好,纯度高,粒度分布均匀并呈六方片状晶体.     

Numerical study on particle size distribution in the process of preparing ultrafine particles by reactive precipitation

Based on the population balance and mass balance in a reactive precipitation process, a numerical simulation model was developed to predict the particle size distribution (PSD) in the reactive precipitation process. The precipitation system of BaCl₂ with Na₂SO₄ to prepare BaSO₄ in aqueous solution was adopted to obtain ultrafine particles in a stirred precipitation reactor and the particle size distribution and the morphology of the particle were observed under transmission electron microscope. It was illustrated by the experimental observation of the micrographs of BaSO₄ particles obtained that apparent agglomeration occurred between the particles, which phenomenon must be taken into consideration in PSD modeling. The population balance equation was calculated by discretization method to obtain particle number and particle size distribution. By implementing the model, the reactive precipitation process in a batch reactor including reaction, nucleation, growth and agglomeration was simulated. The simulation results were validated by the experimental data of BaSO₄ precipitation. Further analysis was endeavored to explore the effects of some important factors such as the supersaturation degree and agglomeration on the evolution of the volume-based characteristic particle size and the variance of volume-based characteristic size of the particles. It was depicted that particle size and particle size distribution are controlled by the supersaturation degree and agglomeration between the particles. Stemming from the analysis in the context, the disciplinarian of the influences of these factors and the method for controlling particle size distribution were presented for the reactive precipitation process.     

Precipitation of pharmaceuticals using a supercritical anti‐solvent (SAS) dechnique: A preliminary study

The aims of this research were to investigate the applicability of the supercritical anti‐solvent (SAS) process on the precipitation of pharmaceuticals (andrographolide and acetaminophen). In particular, the goal of this research was to study the influence of pressure at 10 and 24 MPa on particle characteristics (morphology, crystalline structure, polymorphic form, size, size distribution, and precipitation yield), and to compare the precipitation efficiency of SAS process and evaporation process. Scanning electron microscope (SEM), X‐ray diffraction (XRD), and high performance liquid chromatography (HPLC) showed a significant change in particle size, size distribution, morphology, and precipitation yield, respectively. From an analysis of the results it was found that the crystal size of andrographolide and acetaminophen decreased with increasing pressure. The morphology of andrographolide particles changed from slice‐like to column‐like when the pressure was increased. On the other hand, the acetaminophen particles obtained were found to be monoclinic form (I) under both operating pressures. The SAS process produced small uniform shaped crystals, with a narrow size distribution, high precipitation yield and selective precipitation were also observed.     

反应沉淀法制备亚微米粒子的粒度分布模拟与实验验证

采用基于粒数衡算方程及物料衡算方程的数值模拟方法模拟了包括反应、成核、生长及凝并的反应沉淀制备亚微米粒子的过程,其中颗粒间的凝并过程采用分级模型来模拟,产物颗粒的粒度分布（PSD）由离散化的粒数衡算方程求得.以BaSO₄的反应沉淀体系作为研究体系,将实验测量数据与数值模拟结果进行对比,验证了所构建的数学模型的正确性与适用性.应用此模型进行分析,发现沉淀时间、产物过饱和度及凝并对粒度及粒度分布有着显著的影响.在此基础上,提出了反应沉淀法制备亚微米粒子过程中颗粒粒度及粒度分布的控制方法.     

超细水滑石类化合物的制备

介绍了共沉淀法、成核/晶化隔离法、溶胶-凝胶法、微波照射法、超声波共沉淀法及分散剂介入法等制备超细水滑石类化合物的方法,其中,成核/晶化隔离法、溶胶-凝胶法、微波照射法合成的水滑石化合物粒径都可以达到纳米级。超声波共沉淀法对水滑石粒径的减小较为显著,中值粒径从普通共沉淀的8.06μm减小到超声辐射下的0.53μm;分散剂的分散作用也很大程度上阻止了颗粒的凝聚,中值粒径从0.53μm减小到0.32μm。     

Reactive precipitation of procainebenzyl penicillin

The reactive precipitation process of procaine benzylpenicUlin is reviewed, while such secondary proceeses as ageing, agglomeration, breakage, and the effects of operation parameters on crystal size are emphasized.In the reactive precipitation the ageing of particles has a little effect on the process, while the greater effect comes from the agglomeration and breakage of particles, furthermore, the mixing has also notable influence on the product size. All of these provide the bases for further study on reactive precipitation.     

超细氧化钇粉体的制备

湿化学法制备超细粉体时，反应、分离、干燥以及灼烧都不同程度地影响粉体的粒径及团聚。在传统的草酸沉淀法制备氧化钇基础上对溶液的浓度、pH值以及表面活性剂的选择和用量、颗粒的表面电位进行了考察研究，确定了反应过程中影响粉体粒径的各个因素，得到一次粒径50－100nm，平均粒径0.521μm，晶型良好且具有单分散趋势的超细氧化钇。     

Acid Precipitation of Kraft Lignin from Aqueous Solutions: The Influence of pH,Temperature, and Xylan

In this study, the manners in which temperature (45–77?°C) and the addition of xylan (5?g/95?g lignin) influence the onset of precipitation and evolution of the particle size distribution during acid precipitation of softwood kraft lignin were investigated in situ. No systematic trend between the onset pH of precipitation and the temperature or the addition of xylan could be observed at these conditions: the average onset pH was found to be 9.3. However, the size of the agglomerates increased as the temperature was increased, but added xylan rendered a decrease in agglomerate size. A higher onset pH was measured at increased Na ion concentration. The results indicate that the ionization degree of the phenolic groups influences the precipitation at 1?M Na ions but it is also probable that the degree of ionization of the carboxylic groups (on kraft lignin and xylan) influences precipitation (particle numbers and sizes).     

超声作用对液相沉淀法制取纳米/微米二氧化钛特性的影响

超声处理技术作为一种新型高效的材料加工方法,目前已被广泛研究用于纳米/微米材料的制备工艺中.本文尝试在液相法制备超微二氧化钛粉体材料过程中加入超声处理,探寻超声作用对所制得二氧化钛物料品质的影响规律.研究中针对直接沉淀和均相沉淀两种方式,分别考察了在各个制备阶段中加入超声处理后,所制得的二氧化钛粉体在晶粒大小及团聚体尺...