铂坩埚中用碳酸钠分解硅酸盐脱埚比较困难,且熔蚀少量铂,使Fe~(3+)的还原终点难以判断,溶液中铂对钙镁络合滴定也有干扰,尤其是含铁高的硅酸盐,必须事先酸溶除去大部分铁后才能放入铂埚熔融分解,否则加盐酸分解熔块时Fe~(3+)对铂的氧化会造成严重的损耗。笔者对我室用碳酸钠作熔剂的37个铂埚半年损耗作了一次统计,37个铂埚总损耗为451.6mg,一次损耗量约1.22mg,最多的一个平均每次损耗为2.85mg,最少的一个平均每次损耗为0.80mg。刘国钧报导用Na_2O_2在铂埚中520℃分解超基性岩及铬铁矿每次损耗也在1mg左右。笔者推荐过有效的熔矿方法,在此基础上从热力学讨论了熔矿过程自由能的变化,发现Na_2O_2的分解能力起码比Na_2CO_3大50倍以上.据Belcher试验证实,470℃以前,Na_2O_2对铂基本无熔蚀作用,520℃接近严重损耗的临界温度。综合上述分析我们对硅酸盐,超基性岩进行了熔融试验,归纳方法为:称0.5克试样于铂埚中,加 Platinum crucible with sodium carbonate decomposition of silicate off more difficult, and the corrosion of a small amount of platinum, so that the reduction of Fe ~ (3 +) is difficult to determine the endpoint, the solution of platinum on calcium and magnesium complex titration also interfere, especially iron High silicate must be acid-soluble to remove most of the iron before it can be placed in the platinum crucible melting decomposition, or add hydrochloric acid decomposition frit when Fe ~ (3 +) of platinum oxidation will cause serious losses. The author of my room with sodium carbonate as a flux for the first half of the loss of 37 platinum crucible made a statistical, 37 platinum crucible total loss of 451.6mg, a loss of about 1.22mg, up to an average of each loss of 2.85mg, the least The average loss per one time is 0.80mg. Liu Guojun reported using Na 2 O 2 in a platinum crucible 520 ℃ decomposition of ultrabasic rocks and chromite each loss is about 1mg. The author recommended an effective method of melting ore, on the basis of which the free energy of the melting process was discussed from the thermodynamics and found that the decomposition capacity of Na 2 O 2 was at least 50 times greater than that of Na 2 CO 3 .According to Belcher test, before 470 ℃, Na 2 O 2 The basic no-melting effect, 520 ℃ close to the critical temperature of severe loss. Based on the above analysis, we carried out the melting test on silicate and ultrabasic rock. The induction method is as follows: 0.5g sample is weighed in a platinum crucible, plus