煤液化固渣萃余物的组成结构及铁催化剂活性相回收

Composition and structure of extraction residue of direct coal liquefaction residue and recycle of active phase of iron catalyst

为解决大规模煤直接液化催化剂铁源供应问题,同时实现煤液化固渣萃余物的无害化分质利用,从固渣萃余物中回收铁催化剂的角度进行研究,探索采用物理磁选法进行铁催化剂富集回收的可行性。首先采用粒度分析、XRF、XRD、SEM、TG、SEM-EDX等表征手段对固渣萃余物进行全面的物化性质表征,确定铁催化剂的质量分数和存在形态。由分析可知,工业装置固渣萃余物主要由未反应煤中的炭及残炭、挥发分及灰分组成,其粒度均匀且没有团聚,其中铁元素质量分数为5.96%,铁物种仍以具有顺磁性的Fe1-xS活性相存在,被未反应煤、残余沥青掺杂、包裹,与各种元素Ca、Si、Al、O等均匀混杂分布在萃余物中。在此基础上,选用4种型式的磁选设备在不同磁场强度下进行磁选富集,并将富集后的样品作为催化剂用于煤直接液化反应,考察其直接液化反应性能。试验结果表明,湿式立环脉动高梯度磁选机一方面将所产生的高梯度磁场力作用于磁性催化剂细粉,同时脉动流体力在一定程度上消除了非磁性颗粒的机械夹杂。在清水作为分散介质及洗涤介质下,更有效地实现了固渣萃余物中铁催化剂细粉的精细分离。在640000 A/m外加磁场强度下,含铁催化剂物料富集率为10.48%,铁元素质量分数可达11.37%,高压釜萃取油产率为41.96%,与无催化剂时相比高7.17%,比固渣萃余物提高8.99%,可掺混至新鲜催化剂中实现有效回用,部分解决催化剂铁源短缺的问题。

In order to solve the problem of iron source supply for large-scale direct liquefaction catalyst,and meanwhile realize the harmless separated-utilization of extraction residue from coal liquefaction,this paper conducted a research on the recovery of iron catalyst from extraction residue,and explored the feasibility of enriching recovery of iron catalyst by using physical magnetic separation method.Firstly,the characterization methods,such as particle size analysis,XRF,XRD,SEM,TG,SEM-EDX,were used to comprehensively characterize and analyze the physical and chemical properties of the extraction residue,and therefore determine the contents and existence forms of iron catalyst.From the results ana-lysis,it can be seen that the extraction residue from industrial equipment is mainly composed of carbon in unreacted coal and residual carbon,volatile matter and ash,with uniform particle size and no agglomeration.The mass fraction of iron is 5.96%,and the iron species still exist as the active phase of paramagnetic Fe1-xS,which doped and coated by unreacted coal and residual asphalt,and uniformly mixed and distributed in the extracts with various elements such as Ca,Si,Al,O,etc.On this basis,four types of magnetic separation equipment were selected for magnetic separation enrichment under different magnetic field strengths,and the enriched samples were then used as catalysts for direct coal liquefaction reac-tion to investigate their performances in direct liquefaction reaction.The experimental results show that:On the one hand,the high gradient magnetic force generated by the wet vertical ring pulsating high gradient magnetic separator is applied to the magnetic catalyst fine powder.Together with using water as dispersion medium and washing medium,the fine separa-tion of iron catalyst powder from extraction residue was realized more effectively.With the magnetic field strength of 640000 A/m,the material enrichment rate of the iron-containing catalyst was 10.48%,and the mass fraction of iron was 11.37%,the extraction oil yield of high-pressure autoclave 41.96%,which was 7.17%higher than that without the catalyst,and 8.99%higher than that with the extraction residue.It can be mixed into fresh catalyst to achieve an effective reuse,to some extent solving the problem of catalyst iron source shortage.