The Research On Preparation And Mechanization Of Geopolymer Based Stone Coalaciding Vanadium Tailings

With the rapid development of extracting vanadium from stone coal, emissions oftailings has gradually increased,amounts of tailings caused waste of resources andland shortage and pollution of the environment and security risks and other issues,increased the cost of production, but also seriously hamper sustainable developmentof vanadium extraction industry. Geopolymer is a new developing cementitiousmaterial in recent years, which consists of silicon aluminum materials under theaction of alkaline activator with appropriate technology.The products show a goodperformance and has great prospects. As the stone coal vanadium tailings have a highcontent of Al and Si, the tailings can be used as base materials to prepare forgeopolymer. From the perspective of resource utilization, protection of environment,online circulation and zero emissions of the secondary resources, utilizing tailing toprepare for geopolymer has great environmental benefits, social and economicbenefits. On the based of the study of the properties of vanadium tailings, the studyresearched that vanadium extraction tailings as the main raw materials were used toprepare for geopolymer, mainly including the process conditions of using thevanadium tailings and activated vanadium tailings to prepare for geopolymer,discussing the activation mechanism of vanadium tailings, the performance andstructure and reaction mechanism of geopolymer products. The contents and resultsare as follows:(1)Studying on vanadium tailings were directly prepared for geopolymerThe characteristics of vanadium tailings were analyzed, including chemicalcomposition, mineral composition, particle size distribution, morphology,ash activityand other performance analysis; Having determined the best preparation conditions ofl vanadium tailings geopolymer; the Si/Al of resource materials:tailings/metakaolin=7:3, alkaline activator without cooling was added directly, alkaline activator areconsist of12%NaOH and Na2SiO3/NaOH (mass ratio)=1.0, water-solid ratio was0.16, molding pressure was15MPa. Under these conditions, the maximumcompressive strength of the3d,7d and28d geopolymer products respectively were 14.27MPa,15.18MPa and22.49MPa, the geopolymer products appeared a seriousefflorescence problem after seven days.(2)Studying on activated vanadium tailings were prepared for geopolymerActivating the tailings by3ways: mechanical activation, chemical activation,thermal-chemical activation. Having studied the effects of different activated ways tothe compressive strength of geopolymer products, having determined the bestactivation conditions:12%Ca(OH)2,1.5%Na2SO4, calcination at750℃for90min,the3d,7d and28d of geopolymer products respectively have the maximumcompressive strength of42.762MPa,42.854MPa and44.753MPa.Comparing the study of vanadium tailings and activated vanadium tailings, theresults show that comparing with vanadium tailings geopolymer products themaximum compressive strength of the3d,7d and28d activated vanadium tailingsgeopolymer products increased respectively28.492MPa,27.674MPa and22.263MPa, the efflorescence problem didn’t occur in the28days.(3) Studying on reaction mechanism of vanadium tailings geopolymer productsStudying geopolymer products of different ages by the method ofXRD,FTIR,SEM, and quantitative analysis of the chemical composition that wereprepared under the best condition, having analyzed the formation process ofvanadium tailings geopolymer products which included two parts polymerizationreactions and pozzolanic reaction, the co-exist of alkali aluminosilicate gel, a smallamount of zeolite mineral and CSH gel what made the compressive strength ofactivated tailings geopolymer products increased dramatically.(4) Studying on the activation mechanism of vanadium tailingsBy the activity analysis and XPS analysis of tailing and activated tailing,and theXRD, FTIR, EDS and pore size analysis of geopolymer products, the results showedthat with the vanadium tailings activated, the polymerization degree of silicates andaluminum silicate became low, the structure became unstable, mineral surfacereactivity and gelling improved; the amount of gelling of activated tailings productincreased,the sound hole increased, harmful holes reduced and the specific surfacearea increased greatly, which lead to improve strength of products greatly andinhibited the effloresence phenomenon.