STUDY ON EXISTENT FORMS OF GERMANIUM IN COAL, BANGMAI BASIN, YUNNAN

Bangmai Basin is situated on Linchang granitic body of Sanjiang-Dianzhong longitudinal tectonic system in South-West China. This basin is an asymmetrical inte-rmontane synclinal basin with a Hercynian-Yanshan granitic body (r43-r52) as its basement. Its overlying Strata are made up of the coal-bearing clastic rocks of Ne-ogene. Coal seams consist of lower and upper coal-bearing rocks of N1. the lower rocks ( N11-N15 ) are: clastic rocks, sandstone intercalated with coal, conglomerate layer,fine sand intercalated with clay and lenticular coal and diatomite; the upper rocks (N16-N18)are: interstralified grit and find sand, clayey siltstone and claystone, conglomeratic grit. Germanium ore mostly occurres within the N12 stratiform, stra-toid layers or lenses coal seam. Germanium ore is chiefly of germanium-lignite type. Germanium-bearing coals are mainly lignites with lower graded incoalation. The microcomponents of coals mostly are collinite-semicollinite intercalated with stable components (cuticle,resinite and spore etc. ) and mineral elastics. The coal's type belongs to semidurain, semiclarain duro-clarain and claro-durain. In order to probe into the existent form of germanim in coal, we have adopted five kinds of analytical methods. They are electronic probe analysis ( linear scanning ), separation of heavy liquid (six samples were separated in the solution of v-arious specific gravities, namely 1 . 20, 1 . 28, 1 . 35, 1 . 45, 1 . 55, 1 . 80, 1 . 80 ), electric osmosis, chemical extraction-humic acid, bitumen and grade-extraction ( suitable chemical reagent and condition are chosen for the determination of metallic existent state in samples ) . We carried out simulated test of humic complex germanium in the laboratory, beside analysis.According to infrared spectral analysis, changes of spectral zone w-ere found, that was 1700cm-1 wavecrest almost disappeared, 1250cm-1 peak weaken-es and 1600cm-1 peak strengthened, 1400cm-1peak slightly strengthened. No doubt, these illustrate the formation of humic germanium complex. Afterward, through d-ifferential thermal analysis and measurement of pH variation of media,these further prove the presence of humic germanium complex. In summary, The author considers that the existent forms of germanium in uranium-bearing coals mainly are: 1 . keep chemical combination with organic matter closely, usually take the form of humic germanium complex and germanium organic compound. 2 . In the state of absorption, germanium is absorbed by some organic matter, clay minerals and limonite etc. 3 . A few part take isomorphous form. Geological concentration conditions for mineralization are favorable structure and paleogeographic enviroment of lithofacies, rich germanium source and advantageous geohydrologic state etc. Simultaneously the incoalation of coal-bearing strata controlled the whole process of germanium mineralization.