kinetics of the chemical leaching of chalcocite from a low-grade copper ore in a ferric sulfate medium was investigated using the constrained least square optimization technique. the experiments were carried out for different particle sizes in both the reactor and column at constant eh, ph, and temperature. the leaching rate increased with increase in the temperature. about 50% of the cu recove...

Proper N fertilizer and irrigation management can reduce nitrate leaching while maintaining crop yield, which is critical to enhance the sustainability of vegetable production on soils with poor water and nutrient-holding capacities. This study evaluated different methods to measure nitrate leaching in mulched drip-irrigated zucchini, pepper, and tomato production systems. Fertigation rates wer...

Nitrogen (N) losses negatively impact groundwater quality. Spring wheat genotypes varying in N-fertilizer recovery were studied (by using lysimeters) for their potential to minimize NO3-N leaching during spring and summer, over a three-year period. Additionally, we examined to what extent root growth and NO3-N leaching explain the well-known difference found between apparent and isotopic N reco...

Au-Ag noble metal wastes represent a wide range of waste types and forms with various ballast elements and components. The thiourea process of gold and silver extraction from ores, concentrates or secondary raw materials consists of gold and silver leaching into the thiourea solution and the consequent precipitation of these metals from the solution. Due to the non-toxic character of thiourea i...

To determine dominant factors on arsenic leaching from the coal fly ash, arsenic leaching test under a constant pH was performed. Twelve fly ash samples were collected from two coal fired power plants (600 MWe) having different boiler types. Arsenic in the raw coal was almost all associated with the fly ash in both power plants; however arsenic leaching fraction was strongly differed in boiler ...

Leaching properties of Pb, Cd, Zn, Cu at pH of 2-6 using different inorganic acids (hydrochloric acid, sulfuric acid, nitric acid) and organic acids (acetic acids, citric acid, malic acid, succinic acid) aiming at polluted sediment at downstream of a non-ferrous metal smelting enterprise is discussed. Results showed that leaching concentrations of 4 metals decreased with increasing pH. Among al...

A preliminary survey of an arsenic contaminated site from an abandoned copper smelting facility and feasibility study of using solidification/stabilization (S/S) process to treat the contaminant waste were undertaken. It was found that the waste, located in the three-flue gas discharge tunnels, contained 2-40% arsenic. The pH of the contaminated waste is extremely low (ranging from 1.8 to 3.6)....

Precious metals are the most attractive resources in waste printed circuit boards (PCBs) of mobile phones. In this work, an alternative process for recovering Au, Ag, and Pd from waste PCBs of mobile phones by supercritical water oxidation (SCWO) pre-treatment combined with iodine-iodide leaching process was developed. In the process, the waste PCBs of mobile phones were pre-treated in supercri...

The modelling of pesticide transport through the soil and estimating its leaching to groundwater is essential for an appropriate environmental risk assessment. Pesticide leaching models commonly used in regulatory processes often lack the capability of providing a comprehensive spatial view, as they are implemented as non-spatial point models or only use a few combinations of representative soi...

In order to better understand the role of coal gangue in potential environmental and ecological risks, the leaching behavior of trace elements from coal gangue has been investigated in an open-cast coal mine, Inner Mongolia, China. Four comparative column leaching experiments were conducted to investigate the impacts of leaching time, pH values and sample amount on the leaching behavior of trac...