ザンセートを利用した廃水中のCu²⁺イオンの浮上分離について

抄録

In a previous paper dealing with the removal of Cd²⁺ ions with xanthate, it was shown that xanthate was excellent as a selective precipitant and that Cd²⁺ ions could be removed selectively from mine water containing appreciable amount of Fe²⁺ and Zn²⁺ ions. It is the purpose of this paper to report some results on the removal of Cu²⁺ ions by use of xanthate.
The residual concentration of Cu²⁺ ions can be reduced to the water quality criterion by use of suitable amount of methyl xanthate. The use of excess amount of methyl xanthate, however tends to decrease the removal per cent of Cu²⁺ ions. Analysis of Cu²⁺ ions in the filtrates of residual solution of flotation indicates that the decrease in the removal per cent of Cu²⁺ ions is ascribed to the suspended fine particles of Cu-xanthate precipitates. The dispersion of fine particles of Cu-xanthate becomes appreciable when the peripheral speed of the impeller of flotator was small. The effect of aeration by which Cu-xanthate particles are flocculated may be interpreted in terms of “pseudo-flocculation”, i. e. the flocculation of particles through air bubbles.
The influence of coexisting ions such as Fe²⁺ and Zn²⁺ ions on the removal of Cu²⁺ ions with methyl xanthate is smaller than that on the removal of Cd²⁺ ions with iso-butyl xanthate.
There are many cases where mine water contains both Cu²⁺ and Cd²⁺ ions. Accordingly, in the case of removal of Cd²⁺ ions from mine water by use of higher xanthates, an amount of higher xanthates that are expensive is consumed by coexisting Cu²⁺ ions. In order to reduce the amount of expensive higher xanthate, it is recommended that Cu²⁺ ions are removed by methyl xanthate prior to the removal of Cd²⁺ ions with higher xanthate.
In the system containing both Cu²⁺ and Zn²⁺ ions, Cd²⁺ ions are coprecipitated with Cu-methyl xanthate. The dosage of methyl xanthate which is used to remove Cu²⁺ ions should be minimized in order to avoid the coprecipitation of Cd²⁺ ions. Thus, after removing Cu²⁺ ions by methyl xanthate 1.25 equivalent to Cu²⁺ ions (in the case where initial concentration of Cu²⁺ ions is 10mg/l) or 1.5 equivalent to Cu²⁺ ions (in the case where initial concentration of Cu²⁺ ions is 3mg/l), Cd²⁺ ions, the initial concentration of which is 1mg/l, can be reduced to the water quality criterion by the addition of iso-butyl xanthate 2.5-3.0 equivalent to Cd²⁺ ions.