STUDY OF THE MATERIAL COMPOSITION OF OXIDIZED MANGANESE ORE OF THE DAUTASH DEPOSIT AND OBTAINING FERROMANGANESE BASED ON THEM

ABSTRACT

Work is devoted to studying of material composition of the oxidized manganese ore of the Dautashsky field of Uzbekistan for the purpose of their further enrichment and receiving from them of a concentrate and feromargancy production. In this case, the size of the crushed particle of the manganese-containing initial ore is 5 mm. As a result, the extraction of manganese in the main fraction reached up to 84.1%. And with the addition of the method of electromagnetic separation of narrow classes according to the recommended technological scheme, the extraction of the main fraction of manganese reached up to 92.3%. By means of electromagnetic separation, the resulting crushed products were separated into magnetic and non-magnetic fractions, in which the extraction of the magnetic fraction reached up to 97.3%, and the non-magnetic fraction is 2.7%.

АННОТАЦИЯ

Изучен вещественный состав окисленной марганцевой руды Дауташского месторождения Узбекистана с целью её дальнейшего обогащения и получения концентрата и ферромарганцевой продукции. При этом размер дробленной частицы марганецсодержащей исходной руды составляет 5 мм. В результате извлечение марганца на основной фракции достигло до 84,1%. А с добавлением метода электромагнитной сепарации узких классов по рекомендуемой технологической схеме, извлечение основной фракции марганца достигло до 92,3%. С помощью электромагнитной сепарации полученная измельчённая продукция была отделена на магнитную и немагнитную фракцию, в котором извлечение магнитной фракции достигло до 97,3%, а немагнитная фракция составляет 2,7 %.

Keywords: ore, dioxide of manganese, ferromanganese, enrichment, oxidized of manganese ore, concentrate, structure.

Ключевые слова:  руда,  диоксид марганца, ферромарганец, обогащение, окисленная марганцевая руда, концентрат, структура.

Introduction. In connection with the introduction of high-tech in mechanical engineering, construction, automobile, aerospace, electronics and other industries, in recent decades much attention of world science and technology has been paid to the development of the ferroalloy industry. First of all, this is due to the growth of ferromanganese consumption in the production of high-quality steel grades. They are used in non-ferrous metallurgy (for cleaning zinc solutions), in galvanic cells, for the manufacture of chemical current sources of lithium-manganese or zinc-manganese systems (manganese dioxide is a good depolarizer), in the production of ferrites, magnetite’s, thermistors, adsorbent cartridges, glass, ceramics, mineral dyes, various manganese salts (for example, MnSO₄), which are used to produce manganese micro fertilizers that increase the yield of agricultural crops (especially cotton). In addition, high-quality low-phosphorus manganese oxides (e.g., artificial chemical MnO₂) are raw materials for the production of potassium permanganate KMnO₄ for the medical industry (pharmacopeia permanganate) and for technical purposes (technical permanganate). Manganese dioxide MnO₂ is used as an additive to manganese ores in the production of ferroalloys, etc. Therefore, the production of manganese products tends to grow significantly; hence, the important role of manganese raw materials as a source of the main component of these alloys is obvious.

Objects of study. Manganese ores and concentrates are supplied to Uzbekistan from Georgia (Chiatura) and Ukraine (Nikopol) [1]. Meanwhile, Uzbekistan has the explored Dautash manganese deposit with approved reserves of more than 1.1 million tons, the ores of which can be enriched and used for the above-mentioned purposes [2, 3].

The studied oxidized manganese ore of the Dautash deposit is characterized by a complex textural and structural pattern, which is due, on the one hand, to the mineral composition of the primary rocks and ores, and on the other, to the intensity of substitution processes. The most common ores are massive and spotted textures. Massive ore is formed by polymineral manganese aggregates, in the composition of which psilomelane predominates. Such aggregates have, mainly, a cryptocrystalline structure and are characterized by numerous inclusions of carbonate material. The spotty texture of the ore is due to the uneven distribution of aggregates composed of oxides, manganese hydroxides and, much less frequently, iron hydroxides, which have different colors [4-7].

Scientific results and their discussion. Vein ores are often present (Figure, a). Veins of different types and sizes are observed. The most common are differently oriented veins with a thickness of 0.02 to 0.7 mm, formed by manganese hydroxides of a cryptocrystalline structure.

Figure. Textural and structural features of oxidized manganese ore:

a) vein texture, magnification x25, reflected light; b) cement and brecciated texture, magnification x25, reflected light; c) reticular and brecciated replacement texture, magnification x25, reflected light; d) corrosion replacement texture, magnification x40, reflected light; e) lantern and corrosion texture, magnification x25, reflected light; f) relict carbonate texture, magnification x25, transmitted light

The ore as a whole is characterized by various substitution structures (Figure, b - c): reticular, lattice, bordered, lantern, and honeycomb. Brecciated and pseudo brecciated ores are also noted, in which fragments of carbonate and, less often, siliceous material of different sizes and shapes are cemented by manganese oxides and hydroxides. Ore cement is of a common, contact-basal type. Its content sometimes reaches 60%. The structure of the cement is cryptocrystalline, sometimes fine-fine crystalline. Against their background, areas of ore with a relict structure are observed (Figure, d). Relicts of carbonate material are present in subordinate quantities and are distributed extremely unevenly in the rudder. It should be noted that the complex textural-structural pattern and polymineral composition of the ore determine the presence of fragments of complex phase composition, in which the minerals are characterized by complex relationships, which is most clearly seen in electron microscopic studies.

Image analysis carried out on crushed rock with a calcite content of 13.32% (Table 1), which in this case can be conditionally considered a non-ore phase, showed that it is represented mainly by material with a size of -0.25±0 mm (96.39%). The maximum length of mineral grains usually corresponds to the grinding size at which its disclosure begins. Consequently, the disclosure of calcite begins with a size of 0.8 mm. Almost average elongation (the ratio of the length to the width of the grains), caused by destruction during crushing of the mineral along its typical cleavage, and low jaggedness indicate a fairly good extraction of the carbonate phase. The optimum crushing size for the purpose of removing carbonate material, judging by the average mass size (0.287 mm) of the mineral, should be 0.3 mm.

A study of the nature of the disclosure of ore manganese minerals showed that in the material with a size of -50 ± 1 mm, manganese aggregates composed of manganese oxides and hydroxides constantly contain an admixture of carbonate and siliceous (mostly opal) material. In the material with a size of less than 1 mm, polymineral manganese intergrowths are also present, individual grains of specific manganese minerals are found in insignificant quantities [8-10].

From the above it follows that the textural and structural characteristics of the ore are unfavorable for its enrichment by traditional mechanical methods. Attempts to maximally open up intergrowths and obtain free grains of specific ore minerals during fine grinding of ore will apparently lead to overgrinding and slagging of manganese mineral phases.

Table 1

Mass and quantitative granulomeres composition of Mn carbonates, histogram of distribution by size classes, manganese content in ore-forming minerals

Study of manganese distribution among ore minerals. The balance of manganese distribution among ore-forming minerals is calculated based on the manganese content in specific ore minerals (Table 2). The exception is rancidities, in which it was not possible to determine the manganese content. Therefore, data on rancidity from oxidized ores of the deposit were used for the calculation.

The distribution of manganese among ore minerals is given in Table 2. Manganese oxides and hydroxides, which make up the bulk of the ore, account for 30.18% of manganese, which is 93.1% of all manganese in the ore. Carbonates, including calcite, contain 3.18% of manganese.

Table 2.

Mineral balance of manganese in oxidized ore

The main part of manganese (70.85%) is associated with psilomelane, which contains 22.97% Mn. In minerals with a high manganese content: pyrolusite, neutite and rancieite, the amount of manganese is, respectively, 0.89; 0.85 and 3.07%. Vernadite accounts for 2.4% Mn. Among carbonates, the majority of manganese (0.66%) is in rhodochrosite, manganocalcite contains 0.22% manganese. Only 0.15% of Mn is associated with calcite. Moreover, it should be noted that in the ore, along with manganese calcite, there is also calcite that does not contain manganese. Garnet contains 1.16% Mn, which is 3.58% of the total manganese content in the ore.

Conclusion. An insignificant amount of manganese (0.05%) is included in the composition of iron hydroxides. It should be taken into account that the determination of the Fe and Mn content in them was carried out practically on monomineral grains. In general, the amount of manganese in iron hydroxides is probably somewhat higher.

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