云南三种典型褐煤腐植酸提取工艺中金属及硅元素的分布特性

Metallic Elements and Silicon Distribution Characteristics in the Process of Extracting Humic Acid from Three Kinds of Typical Lignite in Yunnan Province

以云南省较为典型的三种褐煤为原料,采用碱溶酸析的方法提取其中的腐植酸,考察提取过程常见金属元素K,Ca,Na,Mg,Al,Fe及非金属元素Si的分布规律.结果表明:在腐植酸提取过程中,褐煤中的矿物质主要分布于残渣中;褐煤中金属元素及硅元素含量的本底值和游离态腐植酸在总腐植酸中所占比例决定了残渣及腐植酸中相应元素的含量;腐植酸灰分含量远小于残渣灰分含量.不同种类褐煤所得腐植酸,官能团种类、数量及结构相似,但灰分及矿物质含量差异较大,其中昭通褐煤腐植酸的灰分和各金属元素的含量均高于其他两种褐煤腐植酸,说明不同腐植酸除了通过官能团与金属矿物质进行化学吸附外,还存在大量的物理吸附,这与腐植酸物理结构和表面性质等有关.

The three kinds of typical lignite samples in Yunnan Province were used to extract humic acids by base-dissolving acidification method.This research was focused on studying distribution characteristics of metallic elements such as K,Ca,Na,Mg,Al,Fe and non-metallic element Si in extraction process.The experiment results showed that the minerals in lignite are mainly distributed in the residues in the extraction process.The content of the corresponding elements in the residues and humic acids were determined by the background value of the content of the metallic elements and non-metallic element Si in lignite and the proportion of free humic acid in total humic acid.The content of ash in humic acids was far less than that in residues.Although the functional groups of humic acids from different types of lignite were similar in species,number and structure,the content of ash and minerals varied greatly.Among them,the content of ash and various metal elements of humic acid extracted by Zhaotong lignite are higher than that of the other two lignites,which indicates that not only the chemical adsorption exists between different functional groups and minerals,but also physical adsorption exists.This is related to the physical structure and surface properties of humic acid.