Flotation Beneficiation of Nepheline-Bearing Rocks of Krasnoyarsk Krai
Abstract Generated abstract
This paper reports laboratory experiments on reducing iron impurities in nepheline-bearing rocks from Krasnoyarsk Krai, where iron occurs as magnetic minerals, iron-bearing silicates, and hydroxides. The study compares gravity concentration, electromagnetic separation, and subsequent flotation of the nonmagnetic fraction using oleic acid and pine oil, with sodium silicofluoride to depress nepheline and feldspar. Magnetic separation substantially lowered iron oxide content, and flotation of the optimal particle-size fraction at a pulp ratio of 1:4 further reduced Fe2O3 in the chamber product to about 0.40 percent at higher collector consumption. Microscopic examination indicated that the resulting concentrates were composed mainly of nepheline and alteration products with minor plagioclase and dark-colored minerals.
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FLOTATION BENEFICIATION OF NEPHELINE-BEARING ROCKS OF KRASNOYARSK KRAI
S. S. NESTERENKO, S. A. BABENKO
(Presented by the scientific seminar of the Department of Technology of Silicates, Inorganic Substances, and Electrochemical Production)
Nepheline-bearing rocks of Krasnoyarsk Krai constitute a ready natural silicate, the only major drawback of which is the high iron content. In the rock it is represented by strongly magnetic minerals (magnetite, titanomagnetite) and iron-bearing silicates. Iron hydroxides also occur. The present paper sets forth the results of experiments on extracting various forms of iron from nephelines.
Beneficiation of rock with a size of —0.25 mm on concentration tables, with threefold repetition of the gravity process for the light fraction, gave an iron oxide content in the beneficiated product equal to 3.56%, with a content in the initial sample of 6.22%.
Electromagnetic separation at a field strength of 12 thousand oersteds, with a single recleaning of the nonmagnetic product, leads to a reduction of the iron content to 0.70% at a concentrate yield of 62.2%. The addition of one more recleaning reduces the iron oxide content in the nonmagnetic product to 0.44%. The yield of the beneficiated product in this case is 48.4%.
We investigated the possibility of further purification of the nonmagnetic fraction from iron-bearing minerals by flotation. Flotation was carried out in a mechanical-type machine with a chamber capacity of 1 l and an impeller speed of 2000 per min. The water was tap water, its temperature 18°C. The effect on the recovery into froth of iron-containing minerals was studied as a function of the size of the rock fed to flotation, the S:L ratio of the pulp, and the collector consumption.
The nonmagnetic product after magnetic separation, containing 0.70% iron oxide, was subjected to flotation. Preliminary experiments found that the best flotation results were obtained using oleic acid and pine oil. Sodium silicofluoride was used to depress nephelines and feldspars [1]. As a result of the studies, it was established that the optimum grain size effectively beneficiated by magnetic separation and then by flotation is the class —0.25+0.075 mm. The optimum pulp density is S:L = 1:4. The results of flotation of nepheline rock as a function of oleic acid consumption are given in Table 1. As can be seen from the table data, the iron oxide content in the chamber product decreases with increasing collector consumption. Thus, at an oleic acid consumption of 500 g/t the Fe₂O₃ content in the chamber product is 0.51%; correspondingly, at 0.830 g/t it is 0.40%.
Table 1
Results of flotation of nepheline rock as a function of collector consumption
| Oleic acid consumption, g/t | Yield of chamber product, % | Content of Fe₂O₃ in the chamber product, % |
|---|---|---|
| 500 | 91.7 | 0.51 |
| 660 | 90.0 | 0.49 |
| 830 | 89.5 | 0.40 |
Thus, as a result of the laboratory studies carried out, concentrates with a low content of iron oxides were obtained. Examination of them under a microscope showed that they consist of 75% nepheline and products of its alteration, contain 24% plagioclase, and only 1% dark-colored minerals in the form of hornblende, titanaugite, etc.
LITERATURE
- G. F. Suslov, M. Ya. Antonovich. Flotation of iron-bearing minerals from nepheline ore. Obogashchenie rud, 18, 5, L., 1965.