Study On The Preparation And Application Of A New Type Of Ironmaking Slag Based Tailings Cementing Material

Cementing material is the core of cementation in the mines. It is the key factor determining the cementation intensity, and also the most important factor influencing the cost. Therefore, finding a new cementing material with low cost and eminent properties is becoming a worldwide hotspot.This thesis mainly researches on the preparation of a new type of tailings cementing material for cementation by using ironmaking slag as raw material, through adding activator and hardening accelerator. The research is mainly about three aspects: composition of the material, cementation mechanism and application performance and aims at developing a new type of cementing material which is better than cement.Through the research on Luxin and Laiwu ironmaking slag, suitable activator and hardening accelerator are selected, and the optimal addition is determined. The optimal composition of ironmaking slag based cementing materials are put forward. For the two kinds of ironmaking slags used in the experiment, CaO is the suitable activator, and CaCl₂ is the suitable hardening accelerator. In the mortar experiment of Anhui Nuopu iron tailings, the optimal addition of CaO is 15% and 10% of the mass of Luxin ironmaking slag and Laiwu ironmaking slag respectively. The optimal addition of CaCl₂ is 1% of the mass of both Luxin ironmaking slag and Laiwu ironmaking slag.Through the study on cementing mechanism, it can be found that amorphous gelatin of calcium silicate hydrate (C-S-H) and calcium silicate(aluminate) hydrate (C-S-A-H) are the main hydration products of cementing materials based on ironmaking slag except little ettringite and other crystals.Through testing the indices—uniaxial compressive strength, setting time, collapsed slump and so on, it can be discovered that ironmaking slag based cementing material has favourable application performance, the indices are better than the traditional cement. In the cementation of Anhui Nuopu iron tailings, the three-day uniaxial compressive strength can go up to 1.304MPa and 2.030MPa respectively using the Luxin and Laiwu ironmaking slags based tailings cementing materials when the tailing concentration is 70% and cement-sand ratio is 20%. Under the same condition, the three-day uniaxial compressive strength is only 0.762MPa using portland cement.Research on the application of the ironmaking slag based tailings cementing materials shows that they have favourable adaptability for aggregates of different species and particle sizes. In the cementation of Nuopu iron tailings, Gaoyang iron tailings and Jining fly ash, the three-day uniaxial compressive strength is 1.304 MPa,0.931MPa and 1.375MPa respectively using Luxin ironmaking slag based tailings cementing material.