Insight into the kinetic analysis of acid mine drainage treated by carbonate rock.

Acid mine drainage (AMD) has caused a great impact on soil, surface water, groundwater, plants or other organisms in the mining environment because of its high acidity, high sulphate content, and contains a variety of heavy metals. AMD treated by carbonate rocks have been regarded as a feasible technology for pollution control and applied widely in mine area. However, to date, the kinetics of the reaction between carbonate rock and AMD have not been investigated, resulting in the lack of systematic theoretical guidance for the implementation of this technology. In this study, effects of carbonate particle sizes and reaction temperature on AMD treatment were investigated. The dissolution efficiency of Ca2+ was used to quantitatively reflect extent of reaction, and the leaching kinetics was analysed based on the shrinking core model. The results showed that carbonate rocks with a particle size of 0.5-1.0 mm had the best pH-enhancing performance for AMD and highest removal efficiency for Fe3+ (>98.00%), while the Mn2+ and SO42- were temperature sensitive. The diffusion of solid product layer was the controlling step of the leaching reaction, and the apparent activation energy of the reaction was 12.63 kJ·mol-1.

Study on Tailings Covering System Constructed by Geological Polymerization of Mine Waste, Part 1: Material Characterization and Cover Construction.

Acid mine drainage (AMD) is a serious and persistent environmental pollution problem. At present, many studies have focused on the tailings pond's cover systems. This paper introduced the research results of using tin tailings from Laili mountain to make the covering layer of tailings pond. The first part included a detailed description of tailings characterization and acid production potential. On this basis, the hard layer (HL) was prepared and its feasibility as oxidation barrier was evaluated. It was found that when the proportion of tailings waste was 70%, the immobilization efficiency of heavy metals can reach more than 99.45%, and the pH of leaching solution was about 10.8. Moreover, the beneficial effect of solid waste addition on the HL was also verified. This suggests that HL as a post-mining restorative strategy has strong positive influence on pollution control.

Pollution Characteristics and Risk Assessment of Potential Toxic Elements in a Tin-polymetallic Mine Area Southwest China: Environmental Implications by Multi-Medium Analysis.

A multi-medium system, involving tailing area (tailings, surrounding soils and water) and downstream agricultural area (river water, sediments and farmland soils), was conceived to evaluate the pollution status of potential toxic elements (PTEs, including Fe, Mn, Ni, Cu, Zn, As, Sn, Pb, Cr and Cd) and environmental risks in a tin-polymetallic mine area southwest China. The results indicated that tailings exhibited representative enrichment and combination characteristics of Sn, Cu, Ni, Fe, As, Pb and Cr compared to surrounding soils. Acid mine drainage (AMD) from tailings and other mining-related sources greatly affected river water and farmland soils, resulting in soil acidification and accumulation of Sn, As, Cu and Pb in paddy soils. Overall, potential ecological risks posed by tailings and river sediments, and pollution risks from Cu, As and Pb in farmland should be concerned. Therefore, effective measures should be urgently taken to prevent PTEs and AMD into surrounding environmental media.

[Acid Mine Wasteland Reclamation by Juncus ochraceus Buchen as a Potential Pioneer Plant].

Ecological reclamation is the major method for the revegetation of acid mine wasteland worldwide. In this study the pH, fertility characteristics, and heavy metal content of soils from Laili Mountain mine wasteland were analyzed. The research also studied the morphological characteristics and the heavy metal in Juncus ochraceus Buchen as well as its resistance to acid, adaptability to soil fertility in abandoned land, and tolerance to heavy metal pollution (e.g., Zn and Cu) to determine its remediation potential as a pioneer plant for acid mine wasteland. Results showed that the pH of soils in the study area were acidic, ranging from 3.46 to 4.01.The contents of organic matter, total potassium, total phosphorus, and available phosphorus was poor, being 10.28-25.75 g·kg-1, 8.84-9.32 g·kg-1, 0.56-0.63 g·kg-1, and 1.82-5.72 mg·kg-1 respectively.The contents of Zn, Cu, and Fe in the soil ranged between 54.93 and 114.49 mg·kg-1, 92.53 and 127.59 mg·kg-1, and 47133.60 and 112259.63 mg·kg-1, whereby the Cu content was 1.85-2.55 times higher than the risk screening value. The height of Juncus ochraceus Buchen in the study area ranged from 43.77 cm to 55.42 cm, which was shorter than the average plant height of the control group (51.38-57.66 cm); however, this was not a significant difference, thus indicating that this plant was resistant to acidic soil and heavy metal pollution.Further analysis showed that Juncus ochraceus Buchen had accumulating capacity for both Cu and Zn, and transferring capacity for Zn as well. Thus, it had potential in heavy metal accumulation and absorption.Plant height was significantly related to the available phosphorus content in the rhizosphere soil. In the future, soil fertility could be improved by supplementing fertilizers containing available phosphorus when Juncus ochraceus Buchen is planted on the land of abandoned mines as a pioneer plant. Comprehensive analysis revealed that Juncus ochraceus Buchen had great potential as a pioneer plant to remediate acid mine wasteland.