Forecast of AMD Quantity by a Series Tank Model in Three Stages: Case Studies in Two Closed Japanese Mines

Shigeshi Fuchida,Masakazu Kadokura,Kenichiro Fukaki,Chiharu Tokoro

doi:10.3390/min10050430

Shigeshi Fuchida, Masakazu Kadokura + Show 2 more

Open Access

https://doi.org/10.3390/min10050430

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Journal: Minerals	Publication Date: May 11, 2020
Citations: 10	License type: CC BY 4.0

Affiliation: Waseda University

Abstract

There are about 100 sites of acid mine drainage (AMD) from abandoned/closed mines in Japan. For their sustainable treatment, future prediction of AMD quantity is crucial. In this study, AMD quantity was predicted for two closed mines in Japan based on a series tank model in three stages. The tank model parameters were determined from the relationship between the observed AMD quantity and the inflow of rainfall and snowmelt by using the Kalman filter and particle swarm optimization methods. The Automated Meteorological Data Acquisition System (AMeDAS) data of rainfall were corrected for elevation and by the statistical daily fluctuation model. The snowmelt was estimated from the AMeDAS data of rainfall, temperature, and sunshine duration by using mass and heat balance of snow. Fitting with one year of daily data was sufficient to obtain the AMD quantity model. Future AMD quantity was predicted by the constructed model using the forecast data of rainfall and temperature proposed by the Max Planck Institute–Earth System Model (MPI–ESM), based on the Intergovernmental Panel on Climate Change (IPCC) representative concentration pathway (RCP) 2.6 and RCP8.5 scenarios. The results showed that global warming causes an increase in the quantity and fluctuation of AMD, especially for large reservoirs and residence time of AMD. There is a concern that for mines with large AMD quantities, AMD treatment will be unstable due to future global warming.

Highlights

Japan has more than 5000 abandoned/closed mines, and about 100 of their sites produce acid mine drainage (AMD) due to the presence of sulfide mineralization [1]
The forecast of AMD quantity was estimated based on the forecast of rainfall and temperature proposed by the Max Planck Institute–Earth System Model (MPI–ESM) with Intergovernmental Panel on Climate Change (IPCC) RCP2.6 and RCP8.5 scenarios
The forecast results showed that temperature rise due to global warming will cause an increase in rainfall, resulting in increased AMD

Summary

Introduction

Japan has more than 5000 abandoned/closed mines, and about 100 of their sites produce acid mine drainage (AMD) due to the presence of sulfide mineralization [1]. The general treatment for AMD is neutralization and sedimentation by addition of a neutralizer, such as lime, calcium carbonate, and sodium hydroxide [2], and solid/liquid separation [3] of the produced sludge from the neutralized effluents. In these treatments, all toxic elements are concentrated into the sludge by precipitation [4,5,6]. To reduce the treatment cost of the addition of chemicals and of sludge generation, for example, a passive treatment

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