Water Quality Characteristics Analysis And Development Of Real-time Environmental Monitoring System Of The 4# Tailing Pond In Dexing Copper Mine

Tailings are the materials left over after the process of separating the valuable fraction from the uneconomic fraction of an ore, which contain relatively few valuable substances and could not be seperated under the current technical and economic conditions. Usually, tailings, as mud-like waste, are discharged into river channel or disposed into the nearby tailing pond with a dam. Thus, tailings and tailing pond are of significant environment pollution sources in the process of mining, especially in the metal mine engineering.The analysis of samples from 4# tailing pond in Dexing copper mine, the acidification experiments as well as the metal leaching experiments under different conditions are conducted in the lab.Water quality of tailing pond is analysed, and the results show as below:The pH values of supernatant tailings are between 11.5 to 12.5. However, the amount of organic substance is not high. After sedimentation, the concentrations of Fe, Ca, Al, Mg in the sediment of tailings are more than the content of Pb, Cd. The pH values in the acid mine drainage are between 2.0 to 2.3. There are large amounts of heavy metals in the acid mine drainage. It is extremely harmful to environment if it is discharged without proper treatment. The in-situ pH values of the 4# tailing pond are between 6.6 and 7.4. Concentrations of most of the heavy metals, including Fe, Cu, Al and Cd, are reduced because of the neutralization of acids and bases. The concentrations of several metals are little higher than the original supernatant tailings, including Mg, Mn, K, Na.The possibility of natural-acidification in the influent of 4# tailing pond is excluded by the static experiment. Moreover, there's little acid production capacity in the sediment of tailings from the experiments of NAPP and NAG.The concentrations of the heavy metals in leaching solutions increase with immersion time. The rate of the metal dissolution increases with the decrease in particle sizes. The concertrations of dissolved metal vary considerably in different pH values. Pb as well as Cr are not detected in leaching solutions within the pH range of 3.0-7.0. Compared with high pH values, the concentrations of Cu, Fe and Zn are more than that at lower pH values. However, Cd is not detected at pH 2.0-7.0.For the sake of knowing the fundamental information of the 4# tailing pond, the investigation and the testing are carried out on site. The monitoring point distribution is designed based on primary monitoring study. The GPRS real-time enironmental monitoring system is developed for pH detection of the 4# tailing pond in Dexing Copper Mine.The acidification prediction method mentioned in this study provides some guidance for the research of in-service tailing pond. The study would be helpful for the pollution control, the operation and closure management of tailing pond.