论文总字数：22990字

摘 要

用无机酸分解磷矿石来制取磷酸的方法称为湿法磷酸工艺，它在我国有着十分悠久的历史。但是，由于多数磷矿石反应活性低，且含有大量杂质，用湿法磷酸工艺生产而来的磷酸往往质量较差，含有大量杂质，其中就有难以用常规的物理化学方法除去的氟硅酸盐污垢（Na₂SiF₆、K₂SiF₆及NaKSiF₆）。本文针对此问题，尝试在实验室中结合工业实际，模拟氟硅酸盐污垢的生成过程，并选择适当的阻垢剂，对氟硅酸盐污垢的生成进行抑制，从阻垢剂的阻垢效果及污垢晶体生长的角度，探讨阻垢剂对此种污垢的抑制过程。

首选，在一定条件下制备氟硅酸盐污垢的晶体，选取三种有机膦阻垢剂和五种聚合物阻垢剂，采用静态阻垢法评判阻垢剂的阻垢效果。之后，用电感耦合等离子发射光谱仪（ICP）测定静态阻垢实验中所获滤液中的离子含量，分别计算有机膦阻垢剂和聚合物阻垢剂的阻垢率，以此来对阻垢剂进行筛选。对静态阻垢实验中的获得的污垢固体，采用电子扫描显微镜（SEM）和X-射线衍射（XRD）的方法对氟硅酸盐污垢晶体的晶貌进行表征。

上述实验的结果表明，本文所选取的几种有机膦阻垢剂和聚合物阻垢剂在一定的条件下，均对实验所生成的氟硅酸盐污垢有一定的抑制作用。静态阻垢实验表明，当阻垢剂浓度在125mg/L~175mg/L的区间内，阻垢剂的阻垢效果最好，且与HEDP、ATMP相比，PBTCA的阻垢效果最佳。此外，聚合物阻垢剂的实验表明，单独使用某一种聚合物阻垢剂的阻垢效果普遍比单独使用某一种有机膦阻垢剂的阻垢效果要好。通过用SEM和XRD对污垢样品进行表征发现，阻垢剂的加入改变了使氟硅酸盐污垢晶体的生长习性，使其晶貌结垢发生了显著变化，晶体颗粒变得更疏松，更分散。XRD结果表明，污垢晶体在阻垢剂加入前后衍射角的角度基本没有发生变化，但有些晶面的特征峰强度明显减弱。文章也对此种现象进行了进一步的推测和分析。

关键词：湿法磷酸 阻垢 氟硅酸盐 晶体 组织形貌分析

Research on Formation and Inhibition of Fluorosilicate Scale in Wet-process Phosphoric Acid

Abstract

Wet-process phosphoric acid technology refers to the method of preparing phosphoric acid by decomposing phosphate rock with inorganic acid, which has a very long history in China. However, because most phosphate rock has low reactivity and contains a lot of impurities, phosphoric acid produced by the wet-process phosphoric acid technology is often of poor quality and contains a lot of impurities, such as those fluorosilicates (Na₂SiF₆, K₂SiF₆ and Na₂SiF₆) that are difficult to remove by conventional physical and chemical methods. In order to solve this problem, this paper attempts to simulate the production process of fluorosilicate scale in the laboratory, and choose the appropriate scale inhibitor to suppress the formation of fluorosilicate scale. From the perspective of scale effect, the growth of scale crystals explores the inhibition process of scale inhibitors to inhibit such scale.

First, prepare crystals of fluorosilicate scale under certain conditions, select three organophosphorus scale inhibitors, use the static scale inhibition method to evaluate the scale inhibition effect of the scale inhibitors, and use the inductively coupled plasma emission spectrometer (ICP) to determine the static In the scale inhibition experiment, the ion content in the filtrate was obtained, and the sufficient ratios corresponding to the three organophosphorus scale inhibitors were calculated to evaluate the scale inhibition effect of the scale inhibitor. For the fouling solid obtained in the static scale inhibition experiment, the crystal morphology of the fluorosilicate scale was characterized by electron scanning microscope (SEM) and powder X-susceptible diffractometer (XRD).

The results of the above experiments indicate that the selected organic phosphine scale inhibitors and polymer scale inhibitors have certain inhibitory effects on the fluorosilicate scale generated under the experiment under certain conditions. Static scale inhibition experiments show that when the scale inhibitor concentration is in the range of 1250mg / L ~ 175mg / L, the scale inhibitor has the best scale inhibition effect, and compared with HEDP and ATMP, PBTCA has the best scale inhibition effect. In addition, the scale inhibition effect of using a certain polymer scale inhibitor alone is generally better than the scale inhibition effect of using a certain organic phosphine scale inhibitor alone. By using SEM and XRD to characterize the dirt samples, it was found that the addition of scale inhibitor changed the growth habit of the fluorosilicate scale crystals, which significantly changed the crystal appearance and scaling, and the crystal particles became more loose and dispersed . The XRD results show that the angle of the diffraction angle of the dirt crystals before and after the addition of the scale inhibitor has not changed, but the intensity of the characteristic peaks of some crystal planes has obviously weakened. This paper also speculates and further analyzes this phenomenon.

Keywords: wet-process phosphoric acid; scale inhibition; fluorosilicate; crystal; structure and morphology analysis

目 录

摘 要 I

Abstract II

第一章 序言 1

1.1研究背景 1

1.1.1 湿法磷酸工艺概述 1

1.1.2 湿法磷酸生产中的问题 1

1.1.3 国内外研究现状 2

1.2 湿法磷酸工艺中结垢方式及结垢过程 3

1.2.1 结垢的成因 3

1.2.2 结垢过程及影响因素 3

1.3结垢的危害 4

1.4阻垢剂 4

1.4.1 阻垢剂的分类 4

1.4.2 阻垢剂的特点 4

1.5 阻垢剂的阻垢机理 5

1.5.1 螯合作用 5

1.5.2 晶格畸变作用 5

1.5.3 抑制作用 5

1.5.4 胶体分散作用 5

1.6 阻垢性能的评定方法 6

1.6.1 静态阻垢法 6

1.6.2 动态模拟法 6

1.6.3 浊度测定法 6

1.6.4 电导测定法 7

第二章 研究内容及意义 8

2.1 课题的研究内容 8

2.2 课题的研究意义 8

第三章 实验方案及内容 9

3.1 试验方案 9

3.2实验仪器和试剂 9

3.2.1 实验仪器 9

3.2.2 实验试剂 10

3.3静态阻垢法对阻垢剂性能的研究 10

3.3.1 方法提要 10

3.3.2 溶液中各组分配比 11

3.3.3 实验步骤 11

3.4 样品表征 12

3.4.1 方法提要 12

3.4.2 实验步骤 13

第四章 实验现象及结果分析 14

4.1 有机膦阻垢剂对氟硅酸盐垢的抑制作用 14

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