钼矿石物相分析及催化极谱法测定钼

为测定钼矿中钼的总量,将矿样与盐酸加热后加硝酸-硫酸(8+2)混合酸蒸发冒烟至干。用150 g.L-1氢氧化钠溶液溶解残渣取代了常用的碱融熔法,在所得上清液中测定总钼量。为溶解钼矿中不同相态,另取一份矿样先用氨水处理以溶解钼华矿(MoO3),在每次分相溶解中所得的残渣先后用40 g.L-1酒石酸溶液和150 g.L-1碳酸钠溶液处理依次溶解出钼钨钙矿Ca(W,Mo)O4]和钼酸铅矿(PbMnO4),在溶解分去钼酸铅矿后的残渣中存在有辉钼矿(MoS2)。将其在580℃灼烧后按测定总钼的溶解方法处理,在所得溶液中测定辉钼矿的钼量。采用催化极谱法测定上述各溶液中的钼量,所用底液为含有氯酸钾、二苯羟乙酸、二苯胍及硫酸的混合液。按所提方法分析了3个钼矿标准样品,所测得每一试样中各物相中钼量之和与该样品的总钼量测定值一致,其相对标准偏差(n=5)均小于3.5%。

Phase Analysis of Molybdenum Ores and Determination of Molybdenum by Catalytic Polarography

For determination of total molybdenum in its ores,the sample was heated with HCl and fumed with mixed acid of HNO3 and H2SO4(8+2) to dryness.Instead of the alkali fusion,the residue was treated with 150 g·L-1 NaOH solution to transform molybdenum into molybdate,and content of total molybdenum was determined in the supernatant.For dissolution of different phases of molybdenum ore,a separate sample was first heated with aqueous ammonia to dissolve the molybdite(MoO3),and insoluble residues obtained from each step of dissolution were treated with 40 g·L-1 tartaric acid solution and 150 g·L-1 Na2CO3 solution in succession to separate the phases of calcitungstomolyoxide Ca(W,Mo)O4] and lead molybdate(PbMoO4) respectively.The molybdenite(MoS2) was in the residue remained after dissolution of PbMoO4,and it was ignited at 580 ℃ and then treated in the same way as for determination of total molybdenum with HCl-HNO3-H2SO4 and NaOH solution,as described above.Finally,contents of molybdenum in each of the above mentioned solutions were determined by catalytic polarography in a base solution containing KClO3,diphenylglycollic acid,diphenyl guanidine and H2SO4.In the analysis of 3 standard samples of molybdenum ores,contents of sum of the 4 ore phases were found to check quite well with the contents of total molybdenum found,with values of RSD′s(n=5) less than 3.5%.