Tailings Settling Characteristics And Rheological Properties

The mine solids waste-tailings from mineral process are quickly increasedas the growing requirements of mineral resources. The traditional tailings wereused of tailings dam for disposal, but the existence of tailings dam likes thesword of Damocles hanging over people’s head. People’s life and ecologicalenvironment were brought a great threat by tailings dam break, and earthecosystem was caused great damage by mined-out area as a result ofunderground mining at the same time. How to make mine tailings get disposedand stacked more reasonable has been paid attention by all the world. Since the1960s, the developed countries had begun to adopt surface stacking andmined-out area filling techniques. Surface stacking and mined-out area fillingtailings techniques are proved to be reliable methods, which get used more andmore widely. Surface stacking and mined-out area filling techniques of tailingsneed that original tailings slurry is concentrated to paste state of a certainconcentration and a certain yield stress firstly, and then these are transported tothe yard through a positive displacement pump with pipelines or filled. However,paste thickener process design is determined by sedimentation properties oftailings, and pipelines and stacks design of the tailings paste are determinedrheological properties. Therefore, in order to design tailings disposal system andtailings paste stacking system more scientifically, sedimentation properties oftailings and rheological properties of tailings paste must be studied.This study in this paper is given priority to the experiments, andsedimentation properties of tailings and rheological properties of tailings pasteare studied respectively. In static sedimentation experiments of tailings, twokinds of appropriate samples of mine tailings are selected firstly, flocculanttypes and adding amount are screened according to the selected samplecharacteristics secondly，static sedimentation experiments of two litres columnare conducted, and then the relationships between solid flux and solidconcentration are determined, which can be used as a simulation of process parameters of continuous sedimentation experiments. In slump experiments oftailings paste, the selected two kinds of samples of tailings in front staticsedimentation experiments are studied respectively by used of organic glasscylinder with different diameter and height, and A HAAKE VT550viscometer isused for measuring their accuracy yield stress.Static sedimentation experiments of two kinds of tailings show, the bestsedimentation solid concentration of copper mine tailings is10%, and bauxitemine tailings is6%. The structured solid flux curves are fitted and analyzed byMatlab and Originlab softwares which use of a variety of sedimentation velocitymodels. By comparing the fitting results and the experimental results, theidentical degree is higher. It is also proved that the selected function model andfitting parameters are reasonable. Underflow concentration of continuoussedimentation process with different feeding rate is predicted by using theidentified solid flux model. The simulated continuous sedimentationexperiments of two kinds of tailings show，sedimentation area of thickener isdetermined according to requirements of the user to underflow concentration ofslurry，overflow water cleanliness and disposal capacity of total solid，and thenthe amount and diameter of thickener will be determined. Slump experimentsof two kinds of tailings paste show that: the impact on the dimensionless yieldstress due to variety of cylinder dimensions. It is also illustrated thedimensionless yield stress from slump test with cylinders of50mm diameter and100mm height chimed well with that measured by HAAKE VT550viscometer.Therefore，The slump test cylinders of50mm diameter and100mm height canbe a reliable method for yield stress measured in site.