CHROMITE CONTENT OF THE PERMIAN-JURASSIC DEPOSITS OF THE VOLGA-URAL BASIN

The chromite content of the Permian and Jurassic deposits of the East European platform’s Eastern part, adjacent to the Urals - the Lukoyanovskoye field and the Sabantuy occurrence, has been established. The economic significance of the Lukoyanovskoe placer chromites is justified by the technology of extracting chromite concentrate, and the Sabantuy paleoplacer has good prospects because of high chromium content in the ore (Cr2O3 15–17 wt%).

Reactivity of Low-Grade Chromite Concentrates towards Chlorinating Atmospheres

The most economically important iron-chromium bearing minerals is chromite. In natural deposits, iron(II) is frequently substituted by magnesium(II) while chromium(III) is replaced by aluminum(III) and/or iron(III) forming a complex chromium bearing material. The majority of mined chromite is intended for the production of ferrochrome which requires a chromite concentrate with high chromium-to-iron ratio. Found mostly in the spinel chromite structure, iron cannot be removed by physical mineral processing methods. In this frame, the present work deals with the reaction of chlorine and chlorine+oxygen with selected samples of chromite concentrates for assessing the reactivity of their components towards chlorinating atmosphere, allowing the preferential removal of iron, hence meeting the chromite metallurgical grade requirements. Isothermal thermogravimetric analysis was used as a reliable approach for the kinetic reactivity investigation. Results indicated a wide difference in the thermal behavior of chromite constituents in a chlorinating atmosphere when considering their respective values of apparent activation energy oscillating from about 60 to 300 kJ/mol as a function of the sample reacted fraction. During the chromite treatment by chlorine in presence of oxygen, chromium was recovered as liquid chromyl chloride by condensation of the reaction gas phase.

Obtaining refractory materials from chromite raw materials of Karelia and physical and chemical processes in their service

The mineral and chemical compositions of the chromite raw materials of the Karelian-Kola region are studied, the physical and chemical processes for the production of refractory materials from chromite concentrate are established, the phase and structure formation during drying, firing and during service are determined. The dependence of some properties of refractories on their material, grain and phase compositions has been established.

The method of processing technogenic tailings of chromium

Taking into account the existing demand for chromium concentrates, the extraction of chromium from technogenic formations of sludge storages of the tailings of chromium ore beneficiation is an important practical task. The comprehensive utilization of beneficiation sludge will increase the profitability of production and solve the environmental problems of the region. The importance of solving the problem of involving in processing tailings is connected not only with the environment but also with the need to increase the production of chromium. Modern gravity enrichment technologies make it possible to efficiently produce chromium concentrates from large and medium fractions of chromite-containing ores, while finely divided sludge is practically not extracted due to the difficulty of separating complex minerals into concentrates and waste rock. This paper presents the results of studies on the gravity processing of tailings. The technology includes the enrichment of the fine fraction-0.2+0 mm of tailings of the dressing plant of chromite-containing ores by gravity methods using a KNELSON centrifugal separator. In technology, the efficiency of the operation of gravity enrichment is provided by the preliminary activation of the fine fraction in a solution of sodium bicarbonate (NaHCO3). With gravitational enrichment, the total chromite concentrate was obtained containing 51.3% Cr2O3. The output of concentrate was 41.7%. The extraction of Cr2O3 in the concentrate was 68.1%.

Improving the Quality of Ferruginous Chromite Concentrates Via Physical Separation Methods

The low chromium-to-iron ratio of chromite ores is an important issue in some chromite deposits. The value of the chromite ore is indeed dictated in the market by its iron, as well as its chromium content. In the present study, a chromite concentrate was reprocessed by gravity (spiral concentrator) and magnetic separation to enhance the chromium-to-iron ratio. Also, detailed characterization studies including automated mineralogy were carried out to better understand the nature of the samples. Enhancing the chromium-to-iron ratio was achieved by using advanced spiral separators which will be discussed in this paper.

Production of Chromium Oxide from Turkish Chromite Concentrate Using Ethanol

In this study, the possibility of chromium extraction from Turkish chromite concentrate and the production of chromium oxide were investigated. For the conversion of chromium(III) into chromium(VI), NaOH was employed, as well as air with a rate of 20 L/min. The effects of the base amount, fusing temperature, and fusing time on the chromium conversion percentage were investigated in detail. The conversion kinetics of chromium(III) to chromium(VI) was also undertaken. Following the steps of dissolving the sodium chromate in water and filtering, aluminum hydroxide was precipitated by adjusting the pH level of the solution. The chromium(VI) solution was subsequently converted to Cr(III) by the combination of sulfuric acid and ethanol. Interestingly, it was observed that ethanol precipitated chromium as chromium(VI) at mildly acidic pH levels, although this effect is more pronounced for K