Experimental Study On Dry Settlement And Consolidation Of An Iron Tailings In Hubei Province

In recent years, lots of safety accidents such as blasting of tailings ponds and collapse of tailings dams have appeared in domestic, and these accidents have significant impact to people’s life and property security. It leads to high attention of the nation, local governments, business owners and the general managerial and technical staff. The traditional stockpiling method of tailings that wet discharge of tailings directly into the tailings ponds or tailings dams has been challenged. As a relatively safe and environmentally friendly processing method, tailings dry discharge and consolidated stockpiling of tailings has received widespread attention. According to conditions of themselves, various regions and enterprises have carried out applied researches and practices of dry discharge and dry stockpiling of tailings with different forms, and have got great achievements. This paper is mainly aimed at studying the dry discharge technology of Hubei xx iron ore dressing plant.Research content of this paper is mainly composed of five parts. The first part is the literature review. The generation and harm of tailings, comprehensive utilization of tailings, dry stockpiling and dry discharge of tailings, consolidated stockpiling of tailings and developing situation were summarized and analyzed.The second part of the paper mainly studied the properties of tailings from the iron ore. There were non-uniform grain composition, presented polarization, high silt content, high moisture content, oozing easily, loose and low bearing capacity. Most of the chemical compositions were similar to that of ordinary Portland cement, and its main composition were slagging elements such as Mg, Ca, A1, Si, and a certain content of weakly magnetic iron ore which difficult to cement of itself.The third part of the paper is study of settlement test of tailings. Flocculant and coagulant were selected and optimized. Systemic experimental study of effect of free settling, settlement of inorganic salt coagulation, settlement of macromolecule flocculant flocculation, coagulation settlement of combined use of inorganic salt and macromolecule flocculant, and different pulp density and graded overflow particle size on settlement results were carried out respectively. Research results showed that the tailings concentration controlled within15%, preliminary classification, flocculation settlement of graded overflow by macromolecule flocculant (cation or anion), dosage of flocculant of15to20g/t, and combined use of grading underflow and flocculation settlement underflow for subsequent processing technology, could meet the requirements of concentrating underflow concentration and the overflow backwater returning to dressing plant for reutilization.The fourth part of the thesis is consolidation test research of tailings, which uses slag as the main material, and adjusts the amount of admixture of minerals activator, alkaline excitation agent, sulphate activator, coal ash and slag, through the change of compressive strength of concretion body, which determined the suitable dosage range of various distribution of gelled material. The test conforms the optimum proportion of four additives by orthogonal test, which enhances the overall performance of concretion agent; the teat analyzes the cement and concretion XRD diffraction atlas, further explains the source of intensity of concretion; the test also analyzes concretion’s SEM atlas and describes the influence of amount of concretion agent on its performance. The formula of consolidation agent is:slag:60%, mineral excitation agent:24%, alkaline exciting agent:7%, sulfate excitation agent:5%, the fly ash:3%.The optimal formula of chemical admixture is:NC:0.7%, AS:1.7%, NS:0.8%, NCO:0.3%. The dosage of chemical admixture is1%of consolidation agent. The dosage of homemade consolidation agent is5%-8%, that the compressive strength of consolidation of seven days can achieve0.4-0.8MPa which can meet the requirements of consolidation storage of tailings.Finally, this thesis makes cost analysis and proposes suggestions for consolidation stockpiling in iron ore tailings in Hubei xx iron ore dressing plant, the combined total cost for the consolidated stockpiling of tailings about23.16to23.16Yuan/t through cost calculation, and lower than that of commodity consolidation agent and Portland cement, meanwhile puts forward the technological process of production of concretion agent and commercial test of consolidation stockpiling of tailings.