Using Steel Slag To Prepare Building Materials By Carbonation Technology

Carbon dioxide emission and industrial waste recycling have become hot spots of the world’s scientific research due to the low utilization of carbon dioxide and steel slag. Based on steel slag and other large industrial waste residue containing a large number of the available active calcium and magnesium components which can be carbonated by CO2, using steel slag and waste stone powder with CO2 to prepare high performance green wall-ground construction materials by carbonation technology was studied in this paper. The influence of liquid-solid ratio, temperature, carbonization pressure, forming method, carbonization time on the performance of building materials products is mainly studied. In addition, the durability of steel slag products was also studied, such as frost resistance, dry shrinkage and resistance to water. Finally, the carbonation mechanism of carbide steel slag was discussed. The main research results are as follows.1. Study on the preparation of steel slag brick by carbonation technologyOptimum parameters of carbonization temperature, carbonization pressure, molding pressure and liquid-solid ratio with fine steel slag powder to prepare steel slag brick was for 60 ℃, 0.3 MPa, 4 MPa, 14%. The highest carbonization efficiency was 15.5% and the compressive strength was 72.2 MPa; Optimum parameters of carbonization temperature, carbonization pressure, molding pressure and liquid-solid ratio with coarse steel slag powder to prepare steel slag brick was for 65 ℃, 0.35 MPa, 3 MPa, 14%. The highest carbonization efficiency was 17.2%. The compressive strength and flexural strength was 99.4 MPa and 13.2% MPa respectively. Compared with fine steel slag powder, the performance of steel slag brick with coarse powder is better.The effect of 6 kinds of exciting agent for Ca(OH)2,Ca CO3,Na CO3,Na CO3,Na OH and Na Cl mixed in steel slag powder on carbonization efficiency of steel slag brick was studied, but the effect on compressive strength of steel slag brick was little. The influence of calcium carbonate on the compressive strength of the product was highest in the 6 kinds exciting agent. In addition, the strength of the product can be improved with the mixed of Ca(OH)2, but the carbonization efficiency of steel slag was reduced.water absorption and softening coefficient were 9.8% and 0.83 respectively, which meet the relevant national standards. The dry shrinkage of brick was 0.051% and this result is lower than 0.06% by required the national standard. In addition, after freezing and thawing cycles up to 30 times, loss rate of steel slag brick in carbonization pressure 0.2 MPa, 0.3 MPa and 0.35 MPa was lower than 2%, which meet the relevant national standards. Therefore, the steel slag brick have good durability.2. Study on using steel slag and expanded perlite to prepare the light wall panelsOptimum parameters of carbonization temperature, carbonization pressure, carbonization time, expanded perlite admixture and liquid-solid ratio with fine steel slag powder to prepare steel slag brick was for 65 ℃, 0.3 MPa, 2h, 30%, 0.65. Under the optimal process parameters, compressive strength and flexural strength was 1.0 MPa and 0.3 MPa respectively and apparent density of light wall panels was 591.3 kg/m3. The coefficient of thermal conductivity was 0.085 W/(m.K).3. Study on the carbonation mechanism of steel slagBy thermodynamics calculation of steel slag carbonation, under the condition with steel slag in higher temperature, carbonization reaction is more easily to react. Leaching amount of alkaline metal-ion in steel slag decided the degree of carbonation reaction and sequestration of carbon dioxide capture. How much steel slag system raise the p H determine the amount of carbonation reaction products. The carbonation efficiency was related to distribution of pore structure in steel slag products. The carbide calcite is the main product of carbonating steel slag, no obvious aragonite crystals existing and hydration of clinker minerals can be promoted by carbonization. Carbonization was from outside to inside by studying the steel slag micro carbonating process.4. Study on the preparation of artificial marble using waste stone powderUnder certain carbonization process, precalcining rate of waste stone powder is higher, the greater is cracks on the surface after carbonization. Optimum parameters of carbonization temperature, carbonization pressure, carbonization time, liquid-solid ratio and molding pressure with waste stone powder to prepare artificial marble was for 35℃, 0.2 MPa, 90 min, 0.45, 4MPa. Specific surface area between 600m2/kg and 750m2/kg was suitable for carbonization. Under the optimum parameters, the strength of the products can reach 51.3 MPa and it meets the relevant national standards. The specific surface area of waste stone powder between 750m2/kg and 800m2/kg is not suitable for carbonization.By carbide slag preparation of lightweight wall building materials, according to the study of using steel slag and waste stone powder to prepare building materials by carbonating technology is an effective method to solve the problem of steel slag and waste stone powder of stockpiling and difficult use, meanwhile solid waste utilization can effectively capture carbon dioxide in industrial tail gas.