黄銅鉱, 銅精鉱等の粉体試料の熱電率
1982 年 98 巻 1128 号 p. 119-124
詳細
1982 年 98 巻 1128 号 p. 119-124
In the previous paper (J. MMIJ) a method for the thermoelectric power measurement of pulverized samples of metal sulphide ores is described in detail. This paper presents the results for the thermoelectric power α of chalcopyrite, white metal, BF copper matte, and 4 kinds of copper concentrates.
Chalcopyrite (Size: 1.4-1000μm)
The coarse samples (about 50-1000μm) have a nearly constant α of about-300μV/deg, hence they provide the semiconducting character of an n-type. From the temperature-dependences of α and the resistance R, the ionization energies Eα and Eσ for α and the conductivity σ, respectively, are calculated according to empiricale quations,
α=const±B/T, Eα=2eB R=const exp (C/T), Eσ=2kC
where B and C are constants, T, e, and k are the absolute temperature, the charge of an electron, and the Boltzmann constant, respectively. The values obtained fall in the range from 0.1 to 0.3eV, which are comparable with that in the literatures.
As for the fine samples less than 10μm, |α|, Eα, Eσ decrease with a decrease in size, and finally α approaches to zero at a size of about 2μm. The decrease of |α| is tentatively illustrated by a shell model of a spherical particle, where it is assumed that the particle consists of an outer shell (α=0) of a constant thickness and an inner core (α=-295μv/deg). The calculated thickness of the shell amounts to about 0.75μm.
Copper concentrate (Size: 3.5-10.8μ)
The values of α, Eα, and Eσ of these samples are comparable with those of the chalcopyrite sample of the corresponding size; two fine concentrates are α=0, while coarse two are apparently an n-type. After re-grinding with a vibrating mill one of the concentrates has converted into a p-type.
White metal and BF copper matte (Size: 4.6/6.7-190μm)
The coarse samples of white metal (larger than 100μm) and copper matte (larger than 10μm) are a p-type (α=700μV/deg) and an n-type (α=-200μV/deg), respectively. The |α| of both samples also decreases with a decrease in size. The decrease of α for the white metal is, similar to the chalcopyrite, illustrated by the shell model. The thickness amounts to about 5μm.
