A Case Study on Sustainable Iron Ore Tailing Management Using Paste Technology

Abstract

Indian mining industries primarily depend upon high-grade fines mainly because of two factors, one is lack of beneficiation infrastructure and high cost of low-grade fines, the second one is lack of proper tail disposal system. Due to lapses in our policies, miners get better premium by selling high-grade fines over low-grade fines. This restricts the flow of low-grade fines into the market. Again tailing disposal is one of the major concerns of beneficiation plants as it requires a lot of space and handling cost. In view of these problems, most of the miners and pellet producers go ahead with direct grinding route only, even if they have a beneficiation facility. This preferred route eliminates the necessity to have a tailing disposal unit, but only at premium. The premium is, higher iron ore fines’ cost and lower downstream efficiency due to associated gangues and slimes in the final slurry fed to filtration unit. This issue can be addressed by finding a midway solution. The solution being coined as partial beneficiation route. This route proposes to beneficiate the feed iron ore fines partially after properly studying the fractional analysis. Amount of tails generated is considerably lower than that of the full beneficiation mode with almost similar slurry concentrate characteristics. This eliminates the need to have a full-fledged tailing pond to some extent. For a 6 MTPA plant, daily tail disposal requirement comes around 700 MT per day. This can be met in two ways. One is filtration other is paste thickener. Filtration has huge capex and opex associated. Also the down times and process challenges are huge. This leaves us with another option i.e. Paste Technology. It enables maximum water recycling, requires small area for storage and provides faster material reclamation and reduces the risk of tailing dam disasters. Paste is a homogeneous mixture of solid and bearing fluid, in our case iron slimes and water. The distinct properties are higher yield stress and solid percentage. This means better storage and uniform drying. The dried slimes can be reclaimed and reused or sold to prospective buyers. Entire cycle is of around 15–20 days. This therefore requires a buffer zone to accommodate around 15,000 MT of paste which can easily be done in an area of 4/5 acres. The operational costs are quiet competitive and lower than the filters. Herein we present our case study on plant scale with a paste thickener. We have chosen the partial beneficiation mode and operated on 24 × 7 basis without having a tailing pond. This surely is a way for future mining operations.