| 摘要 |
FIELD: chemistry. ^ SUBSTANCE: method involves treating averaged samples of the analysed material from dumps with 0.1 n potassium iodide solution, adding sulphuric acid, stirring for 30 minutes, filtering and titration with 0.01 n sodium thiosulphate solution with addition of 2-3 ml of freshly prepared 1% starch solution, with subsequent determination of the amount of sodium thiosulphate used up during titration of the solution after reduction of the sample and calculation of the amount of oxidised substances, wherein three averaged samples of the analysed materials from the dumps are taken and sulphuric acid is added to the first, second and third samples until achieving pH 1.0-1.2, 1.9-2.1 and 4.9-5.1, respectively. Content of fractions which are difficult to reduce is proportional to the difference between values of the amount of sodium thiosulphate used up during titration of the solutions, obtained after reduction of the second and third samples. Content of mildly reducible fractions is proportional to the difference between values of the amount of sodium thiosulphate used up during titration of solutions, obtained after reduction of the second and third samples, and content of easily reduced fractions is proportional to the amount of sodium thiosulphate used up during titration of the solution obtained after reduction of the third sample. ^ EFFECT: high information content and reliability of determining. ^ 1 ex, 2 tbl, 1 dwg |
