Sulfide-Mineral Syntheses from Aqueous Solutions (A Trial of a Diffusion Method)

Research Project

Project/Area Number	60470052
Research Category	Grant-in-Aid for General Scientific Research (B)
Allocation Type	Single-year Grants
Research Field	鉱物学(含岩石・鉱床学)
Research Institution	TOHOKU UNIVERSITY
Principal Investigator	KANO Shimpei TOHOKU UNIVERSITY, REsearch Associate, 選鉱製錬研究所, 助手 (20006034)
Project Period (FY)	1985 – 1986
Project Status	Completed (Fiscal Year 1986)
Budget Amount *help	¥3,200,000 (Direct Cost: ¥3,200,000) Fiscal Year 1986: ¥500,000 (Direct Cost: ¥500,000) Fiscal Year 1985: ¥2,700,000 (Direct Cost: ¥2,700,000)
Keywords	Sulfide Minerals / Hydrothermal Syntheses / 黄鉄鉱の熱水合成 / 硫化ナトリウム鉄
Research Abstract	Iron-sulfide minerals were synthesized from hot aqueous solutions by two methods, diffusion and aging. Furthermore, it was ascertained which aqueous species could play a role of oxidizing agent in the iron sulfide precipitation. 1. Diffusion Method. Two conical flasks containing 1-2mol/l Fe <Cl_2> or Fe <SO_4> and <Na_2> S, respectively, were placed in supporting solution of 1mol/l NaCl and kept at 60゜C for about 60hours. Crystal phases formed in the supporting solution were pyrite, S, and sometimes greigite. The solid phase found in the <Na_2> S flask was NaFe <S_2> , which has not been found in the terrestrial conditions. In the Fe <Cl_2> -flask magnetite formed. All of them were produts under the oxidizing agent of dissolved oxygen. 2. Aging Method. Fe <Cl_2> , Fe <SO_4> , Fe <Cl_3> or <Fe_2> <(SO_4)_3> , all of which contain crystal water, was put into 1mol/l <Na_2> S solution and kept at 70゜C for about 115 hours. When ferrous state iron was used, the produced phase was black material, which was so active that it began to burn spontaneously in the air. Under the slow oxidizing conditions the black material changed to NaFe <S_2> or lepidochrocite. From ferric state iron, pyrite, greigite and S formed. Amount ratio, pyrite/S, is higher in the case of <Fe_2> <(SO_4)_3> than in Fe <Cl_3> . 3. Oxidizing Agent. Clearly, <Fe^(3+)> (aq) and <O_2> (aq) play as oxidizing agent in Fe-sulfide deposition. However, as far as the present experiment goes, <SO(^(2-)_4)> did not show any power of oxidation.