Аннотация:PHASE DISTRIBUTION OF ORE COMPONENTS IN THE SYSTEM GRANITE MELT – FLUORIDE MELT
1KOTELNIKOV A.R., 1KORZHINSKAYA V.S., 1SUK N.I., 2KOTELNIKOVA Z.A., 1SHAPOVALOV JU.B.
1Institute of Experimental Mineralogy RAS, Chernogolovka, Moscow district, Russia
2Institute of Geology of Ore Deposits, Petrography, Mineralogy, and Geochemistry, RAS, Moscow
Melting in the system aluminosilicate (granitic) melt – fluoride salt melt has been experimental investigated at T=800-1200OC and P=2 kbar. The powder of granite (Orlovka, hole 42) preliminary melting at 1200oC, 4 kbar during 6 h and NaF were used as starting materials. As ore components some quantity of REE oxides (La, Ce, Y, Gd, Dy) or Nb, Ta, Ti, or Zr, Hf, V (1 mg of each component) has been loaded to the charge. Two types of charge were used: (1) with initial mixture: 50 mg of granite glass + 5 mg NaF + 5 mg H2O + (3-5) mg of ore elements oxides; (2) with starting composition: 40 mg of granite glass + 20 mg NaF + 6 mg H2O + (3-5) mg of ore elements oxides (at 1200oC). Experiments have been produced in high gas pressure vessel at different regimes: 1) primary melting (1 hour) at T=1250oC, P=5 kbar and then parameters were reduced to necessary conditions with run time during 5 hours; (2) at necessary parameters during 1 day. The coexisting silicate and fluoride salt melts were usually observed in the run products.
For experiments at 900oC (charge with REE) partition coefficients of REE between fluoride (F-f) and aluminosilicate (AlSi-melt) melts have been calculated: Кi=(CiF-f)/(CiAlSi-melt). Following data have been obtained: for Y– 12.3(11.2); for La – 19.2(11.7); for Ce – 13.3(10.5); for Gd – 11.1(8.46); for Dy – 6.10(5.13). It is shown that for 2 kbar values of Кi are an average of 20 % less than for experiments at 1 kbar.
In experiments at 1200oC values of Кi=(CiF-f)/(CiAlSi-melt) (for REE group) practically don’t depend on pressure: for Y – 17.7; for La – 19.1; for Ce – 15.5; for Gd – 14.4; for Dy – 10.4. As compared these data to data obtained at 900oC we can see that values of partition coefficients for La and Ce practically don’t change, but for the group of hard rare earth elements (including Y) values of Кi=(CiF-f)/(CiAlSi-melt) are an average of 37 relative % more. In experiments with additions of other groups of elements (V, Nb, Ta and Ti, Zr, Hf) at 1200oC and P=1 kbar (charge 1) melting phases are absent and at 2 kbar fluoride melting phase (mixture of villiaumite and cryolite melts) are observed only in experiments with V, Nb, Ta (charge 1). This fluoride phase doesn’t content elements of this group. In experiments carried out at 1200oC and P=2 kbar (charge 2) with ore elements groups (V, Nb, Ta) and (Ti, Zr, Hf) fluoride phase is represented by villiaumite (NaF) melt and doesn’t content these element groups.
This study was supported by RFBR, project № 15-05-03393.
