Research On The Backfilling Materials Of Iron Mine

In the process of underground cemented filling mining, there remains a need for cheap, extensively-sourced and well-functioned filling materials to substitute cement so as to reduce the cost of cementing agent. To address this need, this paper studies underground filling materials of iron mine and applies the local-sourced principle of solid waste cemented filling materials. According to the features of tailings and raw materials of different mining areas, it proposes two substitutes for cement:the fly ash cemented filling materials and slag-steel slag cemented filling materials. Then, based on slag-slag steel-desulfurization gypsum cemented agent, this paper discusses the hydration mechanism of slag aroused by sulfate, as well as the principle and effect of slag-steel slag cemented filling agent solidifying heavy metal. By comparing the slag-slag steel-desulfurization gypsum gelling system with P.O. cement solidified lead, this paper reveals the solidification mechanism of lead, especially the effects the occurrence of lead in solidified body causes to the solidification result, and the effects the involvement of Pb ion has on the structure of C-S-H gelling and ettringite crystals. By carrying out the study above, this paper is dedicated to providing basic support for research and theory of the act that slag-steel slag cemented filling materials are used to safely bury dangerous solid waste underground.The fly ash filling materials consist of75%of fly ash,10%of desulfurization gypsum and15%of lime. The gelling material-tailings ratio is1:4. The fluidity of the grout is good and its highest compressive strength after being maintained for90days is11.35MPa with the utilizing rate of solid waste reaching97%. For cemented filling materials whose main raw materials are slag steel and tailing granules, when the proportion of slag-steel is60%, slag28%and desulfurization gypsum12%, the grout can satisfy the requirement for liquidity of automatically flowing cemented filling with compressive strength of filling agent28d reaching4.09MPa, which meets the need for mine filling strength. For filling agent in which the cement-granules ratio is1:4, its free swelling ratio is0.27%and keeps stable in the later period, which can help improve the roof-contacted rate of filling. Also, the compressive strength of28d is5.98MPa, satisfying the requirement for roof-contacted strength of filling.As for methodology, this paper applies methods such as XRD、SEM、 TG/DSC、IR、NMR, etc. to analyze the hydration product and hydration mechanism of slag aroused by sulfate, and further proposes four stages of slag hydration. The result of Pb ion leaching experiment shows that slag-slag steel gelling materials have better solidifying effects on Pb ion than P.O. cement do.. The research finds that slag-slag steel gelling system is more prone to arouse replacement function of Pb ion and Ca ion. This makes it easier for the lead ion to be captured to enter the silicon-oxygen tetrahedron network of C-S-H gelling and ettringite crystals to balance electric charge. Besides, it is also easier for the lead ion to substitute the captured Ca ion in the lattice, forming a large number of macromolecule double-salt precipitation such as Pb-doped ettringite, Pb-doped zeolite, Pb-doped C-S-H and iron-doped vitriol ((Pb,H+)(Al3+,Fe3+, Fe2+)3(SO42-, AsO43-)2(OH)6) so that solidified Pb ion can be prevented from being leached.