The beneficiation of MgO component in dolomite ore by froth flotation was investigated in this research. Dolomite is an important mineral resource as an industrial material, however, it is not abundant in quantity of resources and the grade of MgO in dolomite ore available in Japan is lowering after consuming for a long time. As the crystalline structure and physical characteristics of dolomite (Ca0.5Mg0.5CO3) are similar to those of calcite (CaCO3), the separation of those mineral particles has been difficult and the technology of beneficiation of low grade dolomite ore has not been developed. In order to satisfy the future requirement of dolomite with high grade MgO utilizing available resources, a technical possibility for the beneficiation of dolomite ore is considered to be important and a research of the technology for the beneficiation has been carried out. The targeted grade of MgO in dolomite ore is 19.0% or more in this research to be accepted by industries. We confirmed that the targeted beneficiation can be achieved by means of froth flotation with the cationic collector of dodecylaminacetate (DAA), and investigated the mechanism which causes the separation of the minerals with similar natures, calcite and dolomite. It has been found that the Mg2+ ions dissolved from dolomite function substantially for separation of both minerals in the flotation.
The biodegradable chelating agents [S,S]-ethylenediaminedisuccinic acid (EDDS) and the low biodegradable chelating agent ethylenediaminetetraacetic acid (EDTA) were investigated for their removal efficiency of lead from soil by soil washing. In the soil washing tests, the removal efficiency of lead with EDTA was high in the wide pH range and the efficiency of lead removal with EDDS increased with increasing pH. However, EDDS has no effect on the removal of lead in the acidic region below pH 5.5. Acid contribution was predominant for the removal of lead with EDDS below pH 5.5 and the complexation between EDDS and lead were negligible. The reaction rates for extraction of lead with EDTA and EDDS were represented by the volume reaction model. The activation energies of these extraction reactions are over 55 kJ/mol and the apparent reaction rate constants are not affected by the stirring speeds, therefore it is considered that these extraction reactions are chemically controlled.