On Some Geochemical Properties of Ilmenite

S. A. Babenko

(Presented by the scientific seminar of the departments of KhTF)

Great prospects for supplying the domestic titanium industry with raw material are offered by placer titanium-zirconium deposits, whose ore assemblage is represented by zircon, ilmenite, leucoxene, and rutile. Owing to the fine dispersion of these minerals, the most effective method of their concentration is flotation. A considerable number of works published in recent years have been devoted to the flotation method of concentrating titanium-zirconium placers. A review of the most important of them [1–6] shows that in studies of the flotation properties of rare-metal minerals, including ilmenite, insufficient attention is paid to the study of their geochemical properties.

It is known that ilmenite undergoes supergene alterations, leading it to rutile through a series of transitional forms called leucoxene and well described by R. V. Putilova [7].

The change in the physicochemical properties of titanium minerals in the ilmenite–rutile series affects their flotation properties, especially when natural organic substances are present on the mineral surface. We have established [8] that the organic substance is humic in character and is present on the surface of ilmenite together with a clay film. The clay film is easily separated from the mineral after dissolution of the humic substances in a weak alkali solution or after extraction with organic solvents: acetone, benzene, methanol.

The aim of the present work was to establish the forms of bonding of natural organic matter with iron, which is a mobile element during supergene alteration of ilmenite.

The fact that ilmenites contain insoluble organic matter indicates a chemical bond between organic and inorganic components. The chemical bond can be confirmed by studies of the solubility of minerals in hydrochloric and sulfuric acids of low concentrations and in Tamm’s solution, which is a mixture of ammonium oxalate and oxalic acid. Extracts with Tamm’s solution give an indication of the quantity of readily mobile forms of iron, represented chiefly in the form of an organo-mineral complex [9]. The essence of the method was as follows: a 5 g weighed portion of the object under study was placed in a flask with a capacity of 150–200 cm³, 50 cm³ of solvent was added, and it was stirred on a mechanical

in a shaker for 2 hours. After shaking, the solutions were filtered, and the content of iron oxide in the filtrate was determined.

The results given in Table 1 for the extraction of iron oxide upon its dissolution from the total content in ilmenite and in the clay film removed from ilmenite show the different ability of the reagents used to dissolve iron. A sulfuric-acid medium promotes better dissolution of iron than a hydrochloric-acid medium, especially for the initial ilmenite (extraction of $\mathrm{Fe_2O_3}$, respectively, 0.12–0.03%).

Table 1

Solubility of ilmenite and of the clay film separated from the mineral surface

Tamm’s reagent, despite the fact that its pH is 3.25, dissolves ilmenite iron better than acid solutions with a lower pH value.

After removal of alkali-soluble organic substances and separation of the clay film, ilmenite is dissolved still better by Tamm’s reagent.

The percentage of iron extraction was 0.81, i.e., greater than was extracted by 1.0 N solutions of sulfuric and hydrochloric acids.

The results of the investigations make it possible to draw the following conclusions:

1. The fact of better dissolution of iron by Tamm’s reagent indicates a chemical bond of the organic substance located on the surface of ilmenite with iron and, possibly, with titanium.

2. Alkali treatment of ilmenite, carried out in order to remove organic substances and clay films, promotes the appearance on the surface of ilmenite of active forms of iron. This circumstance, along with the purification of minerals from organic substances, may explain the improvement in the flotation of ilmenite by oleic acid or its substitutes [10].

LITERATURE

1. Lu Shou-tszy, S. I. Pol’kin. On the mechanism of the influence of pulp pH on the floatability of titanium minerals. Izv. vuzov. Tsvetnaya metallurgiya, No. 2, 1961.

2. D. I. Nedogovorov, A. P. Shapiro. An experiment in the flotation of ilmenite-rutile-zircon placers of marine origin. Byulleten’ tsvetnoi metallurgii, No. 17, Central Institute of Information of Nonferrous Metallurgy, 1957.

3. I. N. Plaksin, E. M. Chatlygina. Influence of oxygen and nitrogen on the flotation separation of titanium and zirconium minerals. Doklady AN SSSR, vol. 119, No. 4, 1958.

4. L. G. Podkosov, K. S. Akopova, N. E. Romanovskaya. Collective flotation of titanium-zirconium sands. In: Flotation of Silicates and Oxides. Proceedings of VIMS, issue 6, 1961.

1. I. V. Chipanin, M. G. Ivanova, A. N. Kozhukhovskaya. Flotation of sands containing ilmenite, rutile, and zircon. Collection of Scientific Papers of Irgiredmet, issue 8, 1959.

2. M. A. Eigeles, A. V. Mashyanova. Rate and selectivity of ilmenite flotation. Ore Beneficiation. Mekhanobr, No. 3 (15), L., 1958.

3. R. V. Lyutova. Some data on substitutions of ilmenite by rutile and anatase. Izv. AN Kaz. SSR, geol. series, issue 3, 1959.

4. V. A. Yankovsky, S. A. Babenko. On the alteration of ilmenite in loose sediments of the Kuskovskaya suite under the influence of adsorbed organic matter. Bulletin of the Western Siberian and Novosibirsk Geological Administrations, No. 3, Tomsk State University Press, 1962.

5. I. G. Tsyurupa. Influence of the degree of crystallinity of iron on their solubility. Proceedings of the Soil Institute, vol. 53, 1958.

6. S. A. Babenko. Flotation of ilmenite from sands containing humic substances. Izv. SO AN SSSR, issue 3, No. 10, 1963.