ABSTRACT
As demonstrated by a number of investigators, silicate tailings can be used to treat heavy metal polluted water and to stabilise heavy metals in waste deposits and contaminated sediments. The removal mechanisms are usually strongly pH-dependent. To achieve optimal adsorption it is often necessary to increase the pH of the system. When using adsorbents possessing a capacity to neutralise acid, the pH increase could be achieved automatically, and without any addition of chemicals. In this study the adsorption characteristics and buffer capacities of two silicate tailings materials from Norwegian mining industry are investigated. The two materials consist of processing plant dust from the milling of nepheline syenite and olivine, respectively. To ascertain the potential of the tailings materials for environmental engineering purposes, the materials were compared to the performance of a glacimarine clay. The adsorption characteristics and buffering capacities were determined in adsorption experiments where l.OOg of adsorbent was exposed to 100ml of solution initially containing 100μM copper or 100μM lead. The results showed that the tailings materials, and especially the olivine material, had superior buffering capacities compared to the clay, and that they were capable of adsorbing copper when exposed to initially acidic solutions. Similar results were obtained for lead.
