Study On The Process Of Preparation Of Active Calcium Oxide Slag Derived From Dicyandiamide

Hundreds of thousands of tons of dicyandiamide slag had been produced in an enterprise each year. It is difficult to dispose the slag due to the small size and low viscosity.In present work, based on dicyandiamide slag, active calcium oxide used as the raw material of calcium carbide is obtained by using purification process, mechanical molding process, carbonization process and calcining process, discussing optimum technologic parameters.The chemical composition and property of the slag have been analysised. The results indicate that the ratios of CaCO3, free C, Fe2O3, MgCO3 and SiO2 are 80.78%,11.02%,0.65%,1.24% and 0.92%, respectively. The diameters of larger granules are about 100 um, while the small one is 30um. According to the investigations, it is feasible that employing the slag produce the active calcium oxide used as calcium carbide. The chemical composition and property of the slag have been analysised. The results indicate that the ratios of CaCO3, free C, Fe2O3, MgCO3 and SiO2 are 80.78%,11.02%,0.65%, 1.24% and 0.92%, respectively. The diameters of larger granules are about 100 um, while the small one is 30um. According to the investigations, it is feasible that employing the slag produce the active calcium oxide. The technologic parameters of the four processes have been discussed. In purification process, dry processing and wet processing have been used for purifying the slags, respectively. The dry processing that uses the 200 mash number standard sieve to sieve and winnow the slags in the settling chamber improves the ratio of CaCO3 above 90% in the slag, while the wet processing with 325 mash number standard sieve acquires the ratio of CaCO3 above 85% in the slag. The processed slags are compacted with the compressive strength of 4MPa based on the CaO as inorganic binder. N2 and CO2 are simulated as the boiler flue gas to carbonize the slags, and the influence factors of carbonation strength are dicussed as well. The compressive strength of carbonized samples is more than 5 MPa, which would be meeting the requirements of industrial production. The calcination time and calcination temperature were discussed with dry slag as raw materials during the calcining process. The optimum temperature and time of calcining process are determined to be 960℃ and 160 min, respectively. The activity, active calcium oxide and compressive strength of calcination samples are 76℃· min-1,91% and 4.7 MPa, which is comparable with the requirements of the calcium carbide production. Finally, the industry line of the slag processing has been designed with the technologic parameters listed above.