废钛基催化剂与钒钛磁铁矿制备含钛球团性能对比

Analysis of the titanium-bearing pellets prepared by a waste titanium-based catalyst and vanadium titanomagnetite

钢铁企业烟气脱硝废催化剂(危废)产生量逐年增加,加强对此类废催化剂的有效处置与利用已成为行业急需解决的关键共性难题.本研究首次提出了将废催化剂添加到球团原料中制备含钛球团利用的新路径.将含废催化剂球团和市场普通含钛球团的制备过程及冶金性能进行对比研究.结果表明:球团原料中添加质量分数5.0%的废催化剂可以显著提高生球综合性能指标,且明显优于以钒钛磁铁矿制备的普通含钛球团.球团焙烧后,含废催化剂球团平均抗压强度为3083 N,高于普通含钛球团的2630 N.含废催化剂球团固结机理表明,废催化剂中TiO_(2)与铁氧化物反应形成Fe_(2)TiO_(5)相粘结,部分未反应TiO_(2)会降低球团抗压强度.两种含钛球团冶金性能与普通氧化球团基本相同,说明含废催化剂球团可以用于高炉护炉冶炼使用.本研究有望为钢铁企业烟气脱硝产生的废催化剂在企业内部资源化利用提供新思路.

NH3-selective catalytic reduction of NOx over a V_(2)O_(5)–WO_(3)/TiO_(2) catalyst is the major control method of NO_(x) and has been successfully promoted and applied in various large steel enterprises in China.The production of waste catalysts(hazardous waste)from flue gas denitrification in iron and steel enterprises increases annually.Harmless landfills and wet purification are widely-employed methods for the treatment of waste catalysts.However,these methods pose environmental problems such as resource wastefulness,excessive amounts of acid/alkali,and considerable secondary pollution.Optimizing the effective use and disposal of such waste catalysts has become a key common problem in the industry.In this work,a novel method for producing titanium-bearing pellets by adding waste catalysts to pellet material was introduced.The feasibility of using waste catalysts to prepare titanium-bearing pellets was comprehensively evaluated by comparing the preparation process and metallurgical properties of the resulting pellets with those of commercially available titanium-containing pellets.The findings of this study reveal that the addition of 5.0%waste catalyst to the raw material can substantially improve the overall comprehensive performance of green pellets.Moreover,the drop number(dropped from 0.5 m height),average compressive strength,and burst temperature of the green pellets increased from 3.8 times,16.5 N,and 487℃(without waste catalyst addition)to 7.7 times,21.5 N,and 553℃,clearly outperforming the ordinary titanium-bearing pellets prepared using vanadium–titanium magnetite(1.4 times,15.0 N,and 542℃).These results could be attributed to the physical properties of the waste catalyst,which is a porous material with abundant hydrophilic groups on the surface.These hydrophilic groups,comprising hydroxyl groups,lead to the presence of more capillary water on the catalyst particle surfaces.Furthermore,the capillary force played an important role in various interactions in the pelleting process,thus improving the performance of mixtures.After roasting,the average compressive strength of the pellets containing the waste catalyst was 3083 N,higher than the 2630 N for ordinary titanium-bearing pellets.However,the short preheating and roasting time resulted in partially unreacted TiO2 being present in the internal pores of the pellets as rutile-type particles.The consolidation mechanism of pellets containing waste catalysts demonstrated that TiO2 in the waste catalyst reacts with iron oxide to form a Fe2TiO5 bond,while unreacted TiO2 reduces the compressive strength of the pellets.The metallurgical properties of the two titanium-bearing pellets are virtually identical to those of ordinary oxidized pellets,indicating that the pellets containing waste catalysts can be used in blast furnace protection smelting.This study offers a new approach for recycling waste catalysts generated by flue gas denitrification in iron and steel enterprises.