Preparation Of Low Temperature Ceramic Cementitious Material By Chrome Iron Slag Activation

Ferrochrome slag, a kind of chromium-containing industrial waste, is discharged from the ferroalloy plants. With the increase of demand for ferroalloy, more than five million tons of ferrochrome slags are generated. The environmental pollution caused by ferrochrome slag has gained wide attentions by many scholars at home and abroad, and a lot of research on the safty disposal of ferrochrome slag has been done, in which, ferrochrome slag based composite cement is an effective way to utilize the ferrochrome slag. The cementious behavior of ferrochrome slag, blast-furnace slag and fly ash was researched in this paper and ferrochrome slag based cementious material with high performance were prepared through physical and chemical activation. In order to prepare highly active ferrochrome slag, blast-furnace slag and fly ash powder, the grinding performance and the activity of three above residue wastes were studied. The results showed that ferrochrome slag was the easiest to grind, and a small amount of grinding agent is added for blast-furnace slag during grinding process due to the particle aggregation. The best grinding time for ferrochrome slag, blast-furnace slagand fly ash was 1 h,2 h and 2 h, and their activities was 0.71,0.89 and 0.79, respectively. The particle size distribution of ferrochrome slag after grinding for 1 h was mainly in the range of 0～10 μm and 10～33 μm.The effects of different mineral admixture on the performance of ferrochrome slag based cementious material were investigated by single factor experiments, and the optimal component of cementious material was obtained as follows:40% ferrochrome slag,20% blast-furnace slag,24% mineral excitation agent,7% fly ash, 5% lime and 4% desulfurization gypsum, and the performance could reach the grade of PC52.5. The phase compostion and microstructure of the cementious material were characterized by means of XRD, SEM and TG-DSC. The hydration products were mainly component of C-S-H gel, AFt crystal and Ca(OH)2. The effects of four kinds of chemical admixture on the performance of ferrochrome slag based cementious material were studied by orthogonal experiment. The optimal dosage ratio is determined:0.6% sodium chloride,1.2% sodium sulfate,0.6% sodium fluoride and 0.7% aluminum sulfate. Furthermore, the hydration mechanism of ferrochrome slag based cementious material and the action mechanism of compound admixtures were discussed by means of XRD, SEM, TG-DSC. The hydration process of ferrochrome slag based cementious material was obviously acceleated by compound chemical admixtures, and the activity of ferrochrome slag, blast-furnace slag and fly ash were improved. The products such as C-S-H gel and Aft could be fastly formed.The ferrochrome slag based cementious material projects was strong enouch to withstand risks throuh tenchnical and economic analysis. The expected social, economic and environment benefits will be remarkable. Ferrochrome slag based cementious material has excellent mechnical performance and good durability, and can be widely used in road engineering to replace concrete.