Basic Study On Dissolution Behavior From Electric Arc Furnace Oxidizing Slag Into Water

In Japan,due to the growing environmental awareness,iron and steel slag is highly considered as a recycled material.In order to improve the supply-demand structure,it is important to develop new applications of iron and steel slag.In China,the utilization rate of steel slag is only 22%,it is essential to develop utilization technology of steel slag.Since the increasing use of steel slag cement in the construction of coastal breakwaters,as for the aspect of environmental safety,it is necessary to carry out basic study on the dissolution behavior of steel slag's elements into water.In this study,EAF oxidizing slag from Topy Industries,Limited was used.A series of fundamental researches on dissolution behavior from EAF oxidizing slag into water were studied.Influences of S/L ratio,particle size,temperature and ultraviolet irradiation on dissolution were investigated.Leaching experiment was carried out mostly on a basis of JIS K 0058-1(Test method for chemicals in slags Part 1:Leaching test method).Conclusions were summarized as follows:(1)Dissolved elements of the EAF oxidizing slag were mainly Ca,Si and Mg.Extraction ratios of them were close to 1%and the dissolution only occurred on the surface of the slag;(2)During the leaching,pH increased rapidly and then decreased with time gradually.The pH values in the leaching experiment exceeded the upper limit of the EQS for conversation of the living experiment;(3)S/L ratio had a significant influence on the dissolution behavior from EAF oxidizing slag into water.With the increase in S/L ratio,final concentrations of Ca,Si and Mg increased firstly,then reduced,and increased again.When the S/L ratio was 0.03 g/mL,the final concentration of Ca was the largest.When the S/L ratio was 0.10 g/mL,the final concentrations of Si and Mg reached the largest values;(4)Particle size had some effects on the dissolution behavior from EAF oxidizing slag into water.When the particle size was 1?2 mm,the final concentrations of Ca and Mg were the largest;(5)With the increase in temperature,final concentrations of Ca,Si and Mg increased firstly and then decreased.At 35?,final concentrations of them were the largest;(6)EAF oxidizing slag irradiated by ultraviolet before leaching showed lower leaching concentrations of Ca,Si and Mg.Pretreatment with ultraviolet irradiation had an inhibitory effect on the dissolution of the slag.Leaching experiment under ultraviolet irradiation tended towards larger leaching concentrations of Ca,Si and Mg.Ultraviolet irradiation during leaching had a promotion effect on the dissolution of the slag;(7)Dissolution behavior of main elements(Ca,Si,Mg,Al,Mn)could be predicted by the relations between concentrations and pH.