Study On New Processes For Preparation Of Metal Strontium And Al-Sr Alloys

In this test, two new processes are studied on preparation strontium by the vacuum aluminothermy reduction and Al-Sr alloys by molten salt electrolysis. In the one half part, according to the strontium nature, thermodynamic calculation of correlative reaction and the principle of the vacuum aluminothermy reduction process, with the laboratory findings of preparation strontium by vacuum aluminothermy reduction compared and analyzed in different parameter conditions, a variety of factors which effect the decomposition rate of SrCO₃ and the percent reduction of strontia are gotten out. The factors include that the decomposition rate of SrCO₃ is influenced by different addition and pressure. They also include that the percent reduction of strontia is influenced by excess coefficient of reducing agent aluminium powder, the particle size of raw material or reducing agent, the pressure of barbecuing, temperature and reduction time. According to those, we can draw the conclusion as follows:(1) Decomposition temperature of SrCO₃ is decreased by adding carbon and alumina in different degree.(2) With quantitative carbon added under the vacuum condition, the decomposition temperature of SrCO₃ is decreased obviously, which can fall 150℃ compared with atmospheric pressure.(3) In keeping 1150℃ of 2.5h, under the 5Pa vacuum condition, the decomposition rate of SrCO₃ nearly keeps in 99% steadily.(4) As the excess coefficient of reducing agent increasing, the percent reduction of strontia increases, but the tendency of increasing is more and more weak. When 25% is exceeded by excess coefficient, the percent reduction of strontia nearly no longer increases.(5) With the raw material and the particle size of reducing agent narrowed, the percent reduction of strontia increases.(6) With the barbecuing pressure increasing, the percent reduction of strontia increases, after the certain value, the percent reduction of strontia decreases instead.(7) With reduction temperature increasing, the percent reduction of strontia increases.(8) The percent reduction of strontia is increasing with prolonging reduction time. In this experimental condition, it will become steady after 2.5h.Yet, it is considered that the percent reduction of strontia is influenced by the cost of raw...