Research And Application Of High Activity Slag Powder From Ni-Cr-Fe Alloy

The sustainable development of cement industry is facing severe challenge due to its high consumption of resources and energy.One of the effective solutions to this problem is the utilization of various industrial solid wastes as cement admixture and concrete mineral addition.This dissertation was funded by research project "Technology and Equipment of High Performance Cement Facing Green Manufacturing" from National Supporting Project of eleventh Five-Years Plan of China Under grants No.2006BAF02A24,aiming at the characteristic of poor easy-grinding and the low activity of Ni-Cr-Fe alloy slag.A mass of experiments were studied in this paper,mainly including alloy slag physical activation,activity stimulation and performance optimization,composite modification of multivariate minerals in the low environmental load.The main solutions are summarized as follows:1.Triethanolamine,KHG,HXG,diglycol,calcium lignosulphonate and composite grinding aids' grinding effect on alloy slag is investigated,and the effect on physical mechanical properties of alloy slag-cement composite cementitious materials paste is also studied.The results indicated that the composite grinding aids is more excellent than the monomer grinding aids in grinding effect,which can prominently increase the fineness and Blain specific surface area of powder and perfects particle size distribution.At the same time,the composite grinding aids can improve the physical mechanical properties of slag-cement system;especially the strength of cementitious materials at 3d and 28d ages.The primary function of grinding aids is a mechanical force chemistry process,which can minish the surface free energy of material particles,the extent of lattice deformation and actuate particle intenerate. Meanwhile,it adsorbs in the particle surface,shields surplus electric charge,prevents the agglutination between particles,sequentially the additive can prevent contra-process of grinding.2.The effect of sodium sulfate,calcined alunite,sulph-aluminate based cement and calcined gypsum on physical mechanical properties of alloy slag-cement cementitious materials is studied.On this basis,a kind of highly active composite activator KHE is produced,the intensity of alloy slag-cement composite cementitious materials pastes can be improved by a large margin after mixing with KHE,and with increasing the content of KHE,the effect will become more obvious.When the content of KHE is 1.0%,the activity coefficient A₇ can to be 78.2%and A₂₈can to be 95.7%,then the alloy slag powder reach the standard of S95,and at the same time,the intensity of alloy slag-cement composite cementitious materials pastes can reach the index of 42.5 cement.3.Alloy slag can be mixed with fly ash or pozzuolana to produce composite Portland cement,32.5 Cement with 60%waste residue and 42.5 Cement with 40% waste residue can be produced with activator.At the same time,high waste residue content of composite Portland cement is tended to small drying shrinkage.The XRD spectrum of complex binder paste sample indicate that activator could depress the characteristic absorption band of Ca(OH)₂ in cementitious material evidently,as well as unhydrated cement,fly ash and pozzuolana;SEM analysis can indicate that activator could increase the amount of C-S-H gel in hydrated mortar,reform the felt in each interface of cement pastes and enhance the compactness of paste structure.