1992 年 41 巻 12 号 p. 1180-1184
Samples at various steps of refining for 2 kinds of animal fats and 10 kinds of vegetable oils and fats were collected from 20 oil refineries, and was determined decrease in trace metals in the crude oils during refining process.
1) For animal fats, iron, magnesium, and zinc, respectively 2.1, 0.6 and 0.4 ppm in crude samples of beef tallow and lard, decreased markedly by deacidifying, and decreased further by bleaching and deodorizing.
2) For vegetable oils and fats, many kinds of crude contained magnesium exceeding 10 ppm, iron exceeding 2 ppm, zinc exceeding 0.5 ppm, and manganese exceeding 0.1 ppm, on the average. As in the case of animal fats, metal content decreased remarkably by deacidifying, and indicated further decrease by bleaching and deodorizing.
3) Nickel content in all animal and vegetable oils and fats showed no decrease by deacidifying, bleaching or deodorizing, owing to the markedly low levels even in the crude. This was also observed for copper content in the oils and fats except rice oil, and for manganese content in animal fats. Arsenic, cadmium, mercury, and chromium could not be detected in any samples.
4) These results suggest that trace metals including heavy metals, present in crude oil are removable not only by deacidifying and deodorizing, but also by bleaching.