By carbothermal reduction of Mg O with black carbon as reduction agent at a high temperature,Mg O was deposited on the surface of Mg O- Ca O clinker（ as coating） to improve the clinker ＇s hydration resistance. In t...By carbothermal reduction of Mg O with black carbon as reduction agent at a high temperature,Mg O was deposited on the surface of Mg O- Ca O clinker（ as coating） to improve the clinker ＇s hydration resistance. In the paper,effect of deposition temperature and holding time on the hydration resistance of the treated Mg O-Ca O,the deposition mechanism and Mg O coating kinetics were investigated with hydration resistance test,X-ray diffractometry（ XRD） and scanning electronic microscope（ SEM）. Results showed Mg O coating grew in a2D mode on the surface of Mg O- Ca O particles; the Mg O coating improved the hydration resistance of the coated Mg O- Ca O clinker,and the coated clinker would become stronger when coated at higher deposition temperature and longer holding time. The measurements also found that Mg O deposition process varied with the deposition temperature： it was mainly a chemical-controlled process at temperatures between 1 400- 1 500 ℃,with an apparent activation energy（ AAE） of 97. 8kJ·mol^（-1）; it would change into a diffusion-controlled process when the temperature rising to 1 500- 1 600 ℃,with apparent activation energy of 19. 2kJ·mol^（-1）.展开更多
In this paper,the effect of high temperature calcination on the structure and properties of bauxite-based homogeneous clinkers calcined at different temperatures for different durations was studied.The results show th...In this paper,the effect of high temperature calcination on the structure and properties of bauxite-based homogeneous clinkers calcined at different temperatures for different durations was studied.The results show that with the rising of calcination temperature and the prolonging of holding time,the volume density of bauxite-based homogeneous clinkers increases and the apparent porosity decreases.After high temperature calcination,the linear expansion of bauxitebased homogeneous clinker is smaller than that of the non-calcined ones.Whether calcined at high temperatures or not,the thermal shock resistance of bauxite-based homogeneous clinkers is good.The crystalline phases of bauxite-based homogeneous clinkers are mainly mullite and corundum.There is more glass phase in the bauxite-based homogeneous clinkers without calcination.After calcination at high temperatures the glass phase content decreases significantly,and the mullite crystals develop better forming the cross-network structure.展开更多
We investigated the effects of calcination temperature(950-1450℃),steel slag content,and the total chromium content of steel slag on the Cr^(6+)contents of clinker samples produced using steel slags with different ch...We investigated the effects of calcination temperature(950-1450℃),steel slag content,and the total chromium content of steel slag on the Cr^(6+)contents of clinker samples produced using steel slags with different chromium contents.Additionally,the reactions of chromium in clinker(produced using steel slag)during calcination were studied.It is found that Cr^(6+)conversion increases with increasing calcination temperature to 1250℃,reaching a maximum of 43%-79%,before decreasing to 18%-42%at 1450℃.Cr^(6+)is mainly formed by the oxidation of trivalent chromium(Cr^(3+))during the solid-phase reaction stage of clinker calcination.Furthermore,the Cr^(6+)content of a clinker sample is proportional to the chromium content of its raw meal precursor and is mainly in the form of water-insoluble calcium chromate(CaCrO_(4)).The chromium in clinker is mainly distributed in tricalcium aluminate and tetracalcium aluminoferrite,however,some is present in silicate minerals.We expect to inform the monitoring and control of the Cr^(6+)content of clinker(produced using steel slag)and resulting cement.展开更多
基金supported by The Industrial Research Project of Shaanxi Province , China under Grant No. 2012k07-07
文摘By carbothermal reduction of Mg O with black carbon as reduction agent at a high temperature,Mg O was deposited on the surface of Mg O- Ca O clinker（ as coating） to improve the clinker ＇s hydration resistance. In the paper,effect of deposition temperature and holding time on the hydration resistance of the treated Mg O-Ca O,the deposition mechanism and Mg O coating kinetics were investigated with hydration resistance test,X-ray diffractometry（ XRD） and scanning electronic microscope（ SEM）. Results showed Mg O coating grew in a2D mode on the surface of Mg O- Ca O particles; the Mg O coating improved the hydration resistance of the coated Mg O- Ca O clinker,and the coated clinker would become stronger when coated at higher deposition temperature and longer holding time. The measurements also found that Mg O deposition process varied with the deposition temperature： it was mainly a chemical-controlled process at temperatures between 1 400- 1 500 ℃,with an apparent activation energy（ AAE） of 97. 8kJ·mol^（-1）; it would change into a diffusion-controlled process when the temperature rising to 1 500- 1 600 ℃,with apparent activation energy of 19. 2kJ·mol^（-1）.
文摘In this paper,the effect of high temperature calcination on the structure and properties of bauxite-based homogeneous clinkers calcined at different temperatures for different durations was studied.The results show that with the rising of calcination temperature and the prolonging of holding time,the volume density of bauxite-based homogeneous clinkers increases and the apparent porosity decreases.After high temperature calcination,the linear expansion of bauxitebased homogeneous clinker is smaller than that of the non-calcined ones.Whether calcined at high temperatures or not,the thermal shock resistance of bauxite-based homogeneous clinkers is good.The crystalline phases of bauxite-based homogeneous clinkers are mainly mullite and corundum.There is more glass phase in the bauxite-based homogeneous clinkers without calcination.After calcination at high temperatures the glass phase content decreases significantly,and the mullite crystals develop better forming the cross-network structure.
文摘We investigated the effects of calcination temperature(950-1450℃),steel slag content,and the total chromium content of steel slag on the Cr^(6+)contents of clinker samples produced using steel slags with different chromium contents.Additionally,the reactions of chromium in clinker(produced using steel slag)during calcination were studied.It is found that Cr^(6+)conversion increases with increasing calcination temperature to 1250℃,reaching a maximum of 43%-79%,before decreasing to 18%-42%at 1450℃.Cr^(6+)is mainly formed by the oxidation of trivalent chromium(Cr^(3+))during the solid-phase reaction stage of clinker calcination.Furthermore,the Cr^(6+)content of a clinker sample is proportional to the chromium content of its raw meal precursor and is mainly in the form of water-insoluble calcium chromate(CaCrO_(4)).The chromium in clinker is mainly distributed in tricalcium aluminate and tetracalcium aluminoferrite,however,some is present in silicate minerals.We expect to inform the monitoring and control of the Cr^(6+)content of clinker(produced using steel slag)and resulting cement.
