Study Of Cementation Characteristics And Mechanism Of MgO-activated Slag Materials On Sulfur Tailings

The utilization of sulfur tailings as supplementary cementious material can accelerate its mass consumption and realize high-value utilization to alleviate the resource shortage,environmental pollution,land occupation and security risks caused by the massive accumulation of sulfur tailings.The ordinary Portland cement sulphur tailings,which form a mass of ettringite and secondary gypsum and cause the degradation of strength and durability.In order to improve the compatibility of sulfur tailings in the cementing system and avoid performance degradation caused by sulfide transformation and safety problems caused by heavy metal leakage,this project carried out research on the performance of MgO activated slag cementing sulfur tailings system.The main contents are as follows:(1)The physical and chemical properties of sulfur tailings of a copper mine were systematically characterized to evaluate whether the tailings could be used as supplementary cementious material and the effect and influence of each characteristic on the cementing system.The tailings of the copper mine are typical sulfur tailings,mainly composed of pyrite,quartz and sulfate.The maximum particle size is 66.9～76.0μm.In different solution environments,the external ions released by sulfur tailings are generally stable,and its stability also meets the requirements of the specification.(2)In order to reveal the influence and mechanism of sulfur content on the properties of alkaliactivated slag mortars,the migration and transformation process of sulfide in alkali-activated slag system with sulfur tailings was analysed by adding different proportions of sulfur content in quartz sand,sulfur tailing and pyrite control system.The results showed pyrite in sulphur tailings oxide into sulfate as an auxiliary activator,and MgO collectively accelerate the hydrolysis and reunion of slag,generating hydrated magnesium silicate,hydrotalcite,gypsum and ettringite.The compacted cemented tailing microstructure has remarkably positive effects on increasement of compressive strength of alkali slag cemented tailing and inhibition of release of heavy metals in sulfur tailing.(3)Based on the theoretical study on the auxiliary activation mechanism of sulfur tailing,the influence of sulfur tailing content on the strength of cemented tailing under different MgO alkali dosage was studied,which provided technical basis for the construction of multistage cementation system and subsequent application.The compressive strength of the cemented tailing is relatively higher when the replacement content of sulfur tailings is 20%,and the strength decreases obviously when the replacement content is 30%and 40%.Under the optimal substitution amount,the strength of 6%alkali dosage cement is higher in the middle and later stage of hydration.This project provides a theoretical basis for the cementation characteristics of sulphur tailings and alkali-activated slag materials,promotes resource utilization of sulfur tailings in the field of supplementary cementious materials,alleviates some problems with accumulation of sulfur tailings,reduces economic cost,safety risk and environmental pressure of the tailings pond,which has important theoretical significance and practical value.Figure 22 Table 21 References 113...