Structure and Content Analysis of Raw Materials for Production of Trimanganese Tetraoxide Pigment

The research aims to reveal the structure, phase, and elemental content of manganese ores from deposits—Bogach (Karaganda region, Kazakhstan) and Zhaksy (Akmola region, Kazakhstan). The samples were studied with scanning electron microscopy with energy dispersive analysis (SEM-EDA), X-ray diffractometry (XRD), Infra-red spectroscopy (IRS). During the research, structural peculiarities, elemental and phase content of the samples have been revealed. The mineral matter of the Bogach deposit ore mainly consists of hollandite, cryptomelane, braunite, calcite, bixbyite, quartz. The Zhaksy deposit ore includes quartz, hollandite, bixbyite, pyrolusite. Bogach ore includes (wt.%) C(10.68), O(32.00), Mn(43.26), Ca(6.36), Si(3.51), Na(0.52), Al(1.13), Mg(0.69), K(1.85). The elemental content of Mn in Zhaksy ore is two times lower. Zhaksy ore includes (wt.%) C(23.77), O(32.1), Mn(21.81), Si(10.52), Al(5.13), K(1.21), Fe(5.47). The obtained data of the conducted spectral analysis indicate that both samples represent a polymineral heterogeneous structure. Conducted research allows to conclude, that by phase-elemental content the Bogach ore can be used for obtaining trimanganese tetraoxide pigment similar to manganese ores from West Sumatera deposit (Indonesia) by top-down method using grinding with a milling tool and high-temperature sintering.

Hydrometallurgical Production of Electrolytic Manganese Dioxide (EMD) from Furnace Fines

The ferromanganese (FeMn) alloy is produced through the smelting-reduction of manganese ores in submerged arc furnaces. This process generates large amounts of furnace dust that is environmentally problematic for storage. Due to its fineness and high volatile content, this furnace dust cannot be recirculated through the process, either. Conventional MnO2 production requires the pre-reduction of low-grade ores at around 900 °C to convert the manganese oxides present in the ore into their respective acid-soluble forms; however, the furnace dust is a partly reduced by-product. In this study, a hydrometallurgical route is proposed to valorize the waste dust for the production of battery-grade MnO2. By using dextrin, a cheap organic reductant, the direct and complete dissolution of the manganese in the furnace dust is possible without any need for high-temperature pre-reduction. The leachate is then purified through pH adjustment followed by direct electrowinning for electrolytic manganese dioxide (EMD) production. An overall manganese recovery rate of >90% is achieved.

Reaction Rate Analysis of Manganese Ore Prereduction in CO-CO2 Atmosphere

Variations in energy efficiency and climate gas emissions in production of manganese ferroalloys are largely related to the solid-state reduction of the manganese ores used as raw material in the production. The gas-solid reduction is known to be dependent on the ore characteristics, making information on the factors governing the kinetics crucial. A reaction rate analysis of thermogravimetric data obtained for the reduction of Comilog and Nchwaning manganese ores in CO-CO2 atmosphere was performed. Experimental variables were CO partial pressure, ore particle size, temperature regimes (isothermal/non-isothermal), as well as heating rate for non-isothermal experiments. The effects of particle size, CO-concentration, and temperature on the reaction rates were quantified. It was found that the reduction rate of both ores was proportional to the inverse average particle size. Different sensitivities towards the CO-concentration in the gas feed was determined, where the rate of Comilog-ore was proportional to $$ p_{\text{CO}}^{0.7} $$ p CO 0.7 , and Nchwaning to $$ p_{\text{CO}}^{1.5} $$ p CO 1.5 . The activation energy of Comilog ore was estimated to be 17 kJ/mol, whereas 63 kJ/mol was found for Nchwaning ore.

ELEMENTAL ANALYSIS OF LOCAL AND FOREIGN RAW MATERIALS FOR THE PRODUCTION OF TRIMANGANESE TETRAOXIDE PIGMENT

In the course of continuation of scientific research in the development of Kazakhstani technology for the production of trimanganese tetraoxide pigment, there have been proposed new methods of analysis which make it possible to investigate new nanostructural materials sourced from local deposits. The results obtained are of practical importance and serve as the foundation for developing new technologically advanced domestic production of a competitive product that is in demand both on the national and international markets. The available methods are not able to highlight the particularity and diversity of Kazakhstani manganese ores due to the uneven distribution of manganese minerals and host (waste) rock, the quantitative ratio of rock-forming components and their variation instability. Methods of energy-dispersive analysis of manganese ores from Kazakhstani Zhaksylyk and Bogach deposits have been put forward, electronic micrographs, spectrograms of samples, diagrams of normalized distribution of elements on the surface of samples have been obtained and a comparative analysis with raw analogue samples of some foreign manufacturers has been performed.