蛍石鉱山廃水の高勾配磁気ろ過

Abstract

Recently the output of fluorite has been increasing in China and environmental problems have been proposed accordingly by the waste water containing fluorine in the flotation plants of Dong Feng and so on. This paper describes the purification of artificial fluorite mill waste and colloidal calcium fluoride by high gradient magnetic filtration (HGMF) with the combined addition of magnetic seed particles and inorganic flocculant. The results are as follows.1) As fluorite and calcite particles suspended in water released calcium ions, the capture of suspended solids by HGMF and the hetero coagulation of each mineral and magnetite were estimated from their zeta potentials in the existance of calcium ions.2) The addition of magnetite which was prepared by the oxidation of ferrous hydroxide was the most effective for the removal of suspended solids in comparison with the use of magnetite prepared by grinding or coprecipitation.3) 0.2-0.5 T of external applied magnetic field was enough to capture suspended solids coated with magnetite. Theemployment of permanent magnet instead of electromagnet is possible, so that the energy cost will be reduced.4) Aluminium sulfate solution was added into suspension and pH was adjusted at 7 to 8 after the addition of magnetite. Thi s conditioning was very effective to purify artificial fluorite mine waste water or colloidal calcium fluoride by HGMF.