Study on the Mechanism and Kinetics of Manganese Release from Waste Manganese Ore Waste Rock Under Rainfall Leaching

Manganese released from manganese ore wastes under leaching poses a serious threat to the local ecosystem and human health. The mechanism and dynamic characteristics of manganese release under the leaching of manganese ore waste rock are studied based on static and dynamic experiment. The concentration of manganese in the leaching solution under the disturbance state is twice as much as that in the static state; the manganese release from the waste rock increases with the increase of the solid-liquid ratio, and the manganese release is 922.35mg/l when the solid-liquid ratio is 1:5; when the particle size of waste rock is greater than 80 mesh, the precipitation amount of manganese is the largest, and the precipitation concentration is 491.3mg/l; at pH = 7, rainfall intensity is 80 With the increase of leaching time, the amount of manganese released rapidly decreased and gradually reached equilibrium; the cumulative release of manganese increased with the increase of rainfall duration. In the dynamic leaching process, the change of pH and EC of leachate has nothing to do with the initial pH of leachate, but has a close relationship with the hydrolysis of minerals in waste; through the fitting results of kinetic model, it is found that the double constant equation model can better fit the kinetic process of release process. The purpose of this study is to provide a scientific basis for the assessment and control of manganese pollution in soil and groundwater in manganese mining area.

The Impact of River Discharge and Water Temperature on Manganese Release from the Riverbed during Riverbank Filtration: A Case Study from Dresden, Germany

The climate-related variables, river discharge, and water temperature, are the main factors controlling the quality of the bank filtrate by affecting infiltration rates, travel times, and redox conditions. The impact of temperature and discharge on manganese release from a riverbed were assessed by water quality data from a monitoring transect at a riverbank filtration site in Dresden-Tolkewitz. Column experiments with riverbed material were used to assess the Mn release for four temperature and three discharge conditions, represented by varying infiltration rates. The observed Mn release was modeled as kinetic reactions via Monod-type rate formulations in PHREEQC. The temperature had a bigger impact than the infiltration rates on the Mn release. Infiltration rates of <0.3 m3/(m2·d) required temperatures >20 °C to trigger the Mn release. With increasing temperatures, the infiltration rates became less important. The modeled consumption rates of dissolved oxygen are in agreement with results from other bank filtration sites and are potentially suited for the further application of the given conditions. The determined Mn reduction rate constants were appropriate to simulate Mn release from the riverbed sediments but seemed not to be suited for simulations in which Mn reduction is likely to occur within the aquifer. Sequential extractions revealed a decrease of easily reducible Mn up to 25%, which was found to reflect the natural stratification within the riverbed, rather than a depletion of the Mn reservoir.