Permeability Prediction of Iron Tailings Including Degree of Compaction and Structure

Deqing Gan,Yunpeng Zhang,Xi Yang

doi:10.1155/2019/3591628

Abstract

The stability of iron tailings dam is affected by the permeability of tailings. Considering the influence of it, it is necessary to analyze the permeability of tailings so as to prevent the recurrence of Brazilian iron tailings dam accidents. Nevertheless, the results of iron tailings permeability from some prediction equations (Terzaghi equation, Hazen equation, and Kozeny equation) cannot be accurate. Iron tailings are various as they can be divided into three categories: (1) silt content is less than 40%; (2) silt content is more than 40%, while clay content is less than 15%; and (3) clay content is more than 15% and less than 30%. Correspondingly, three equations are proposed to calculate the disturbed and iron undisturbed tailings permeability for the three types. And more accurate results come from it. The water-flow paths of the iron tailings are blocked after compaction, and the critical pressure of iron tailings blockage is 200 kPa. Although the porosity is large, some of the pores are isolated from each other when the pressure is larger than 200 kPa. However, porosity becomes too large for permeability calculation after compaction and the calculated permeability gets larger as well (equations (24)–(26)). Correcting the permeability calculation equations is an absolute must. The calculated permeability by the revised equations becomes more accurate (equations (27)–(29)). In fact, the granulometric characteristics necessarily play a vital role in the evolution of the pore interconnections by blocking the water-flow paths and modifying the morphological parameters. More research studies are required to be done in the future.

Highlights

Soil permeability is the ability to allow water to ow under a hydraulic head
5 groups (2-5 series) of iron tailings permeability tests were performed to figure out the difference of permeability coefficients between the undisturbed tailings and disturbed tailings. ird, 13 groups (3-13 series) of iron tailings permeability and compaction tests were performed to figure out the permeability coefficients of compressed tailings
E influence of clay content on the permeability of iron tailings has been shown in Figure 6(b). is figure shows that the permeability coefficients are increasing with the raise of the clay content at first. e reason behind this increasing trend is that the void ratio increases when the silt content exceeds 40% or the clay content is less than 15%

Summary

Introduction

Soil permeability is the ability to allow water to ow under a hydraulic head. It is one of the most signi cant geotechnical properties of soil and gets involved in the design of retaining structures and earthen dams. The permeability coefficient (K) is expressed as a quadratic function of the particle size in the Hazen equation. The permeability coefficient (K) is expressed as a quadratic function of the particle size and void ratio in the Terzaghi equation. Us, the following equation is proposed to predict the permeability coefficient (K) of a sediment [10,11,12,13,14,15]:. The permeability properties of iron tailings were analyzed by fine particle content, structure, and degree of compaction. A series of new equations with improved accuracy for calculating the permeability coefficient of iron tailings were proposed, which plays a major role in analyzing the stability of tailings dams

Materials and Experimental Setup

Test Results

Findings

Discussion