Present study determines conditions for titanium magnetite concentrate processing with fairly complete titanium conversion to the slag and iron and vanadium separation in the hot metal. It is quite difficult to process titanium magnetite concentrate in the blast furnaces due to low fusibility of charge and direct electrical melting causes process instability. Present work is devoted to development of concentrate double stage smelting process with little soda additions, including solid-phase recovery at the first stage using specific coke as a reductant, avoiding concentrate oxidation and including its preliminary thermooxidation.

Mix charge made of concentrate, soda and specific coke was granulated in water, dried at 130°C, pellets were placed in graphite crucible, and later on it was set up in the centre of the furnace in alundum crucible. Temperature regimen was fixed under following parameters: temperature at the first stage is 1250^оС; soaking time is 50 min; temperature at the second stage is 1500 - 1650^оС; soaking time is 35 min. It is established that little soda additive (estimated 3-4% Na₂O) to the charge of titanium magnetite concentrate recovery smelting performs as coagulant during briquetting, as catalyst in course of solid-phase recovery, as inhibitor of DRI briquettes secondary oxidation as slag thinner during smelting. In course of titanium magnetite concentrate reduction smelting process soda interacts to SiO₂, Al₂O₃, TiO₂ oxides forming sodium silicates and titanates.

Double-stage technology of titanium magnetite concentrate reduction smelting both with soda addition and without oxidation and preliminary iron oxidation of titanium magnetite concentrates till hematite was developed. Optimal process parameters were determined. Following parameters were obtained: hot metal yield was ~55% out of concentrate weight, slag yield – 23,3-25,8%, carbon-free slag content, wt. %: Fe=1,0-1,6; TiO₂=62,7-61,9. TiO₂ yield in the slag is 89,6-94,1%. Hot metal contains, %: 5,51 С; 0,36 Ti; 0,35 Mn; 0,04 Si; 0,23 V.  Vanadium yield in iron was 53,0%.

In the aspect of growing production rates in most metallurgical industries in the recent past, the accumulation of the associated by-products like sludges, slags and dust also followed this trend  [1]. One such residue is the dust generated by stainless steel production, which contains both Cr and Ni in significant amounts [2]. If not recovered, this would conclude with a double loss for producers, as they lose these metals in residues, for which in most western countries landfilling costs arise. Furthermore, this also constitutes an enormous burden for the environment and eventually humanity itself, which suffer under the consequences of potentially hazardous compounds, like hexavalent Cr, accompanied in the respective residues [3]. Most of the today's applied processes to recover these metals are of pyrometallurgical nature, which aside from being energy intensive and carbon based, are only capable of producing a mixed Fe-Ni-Cr alloy and are few and far between [4]. For those reasons, the authors have studied potential hydrometallurgical treatment for such Cr-Ni-rich dusts as for their recovery. In the first steps, the dust was characterized thoroughly, leached with hydrochloric acid, and investigated for the optimal leaching parameters. The aim of the follow-up recovery was the separation into a Cr-rich and Ni-rich fraction, by the means of neutralization precipitation with NaOH. These experiments were both conducted with synthetic solutions. The experiments conducted have shown that a selective recovery of Cr and Ni is plausible under specific conditions to gain these metal specific rich fractions. These products were characterized by SEM-EDX among others to determine the potential usage for ferro-alloys or other industries.

In sorption processes, one of the characteristics of the interaction between a carbon sorbent and an extracted compound is the distribution of the latter on the sorbent surface. The aim of this work was to study the distribution of noble and rare metal ions on the surface of carbon sorbents using scanning electron microscopy (SEM) with energy dispersive (EDS) and wavelength dispersive (WDS) spectroscopy. Activated carbon products obtained from special coke fines (CBCS) and rice husk (RH_p-850VA) were selected as objects of study. 

CBCS was produced according to the method written elsewhere [1]. Fines of special coke (+2-5 mm) were elutriated in water with slow stirring for 15 min. The wet carbon-containing material was activated with water vapor at 850 °C for 30 min. The furnace heating was turned off at the end of the activation process while water vapor was continued to be supplied to the reactor for another 30-40 min to cool the activated product to 500 °C. Then the vapor supply was stopped and the prepared material was kept in the reactor until cooling to a temperature of 60 °C. 

To produce RH_p-850VA, rice husk was washed with water, dried, pyrolyzed at 450 °С for 30 min, activated with water vapor at 850 °С for 30 min, and boiled with 70 g dm^-3 sodium hydroxide solution at a Solid (g) : Liquid (cm³) (S:L) ratio of 1:10 for 90 min. Then it was washed with distilled water until the wash water was neutral and dried at 150 °С for 1 h. 

Realistic production solutions obtained in gold-bearing ore (2.5 mg dm^-3 of Au ions) and lead production cakes (640 mg dm^-3 of Re ions) processing were used. Gold and rhenium adsorption to load sorbents was carried out under dynamic conditions. Gold- and rhenium-containing solutions were passed through 20 cm³ columns filled with CBCS and RH_p-850VA, respectively. The experiments were continued until the concentrations of metal ions in the filtrates became equal to their concentrations in the initial solutions.

The sorbents before and after the sorption processes were tested using SEM and EDS, WDS mappingby elements. It was determined that both sorbents differ each other by their structures. Although the main element of the studied materials was carbon, carbon particles had different shapes and structures. CBCS was a porous material with a developed porous structure. The pores are predominantly round and/or oval in shape and up to 20 microns in size. As shown in [1], nano-sized pores were not detected. The RH_p-850VA sample had a microfibrous structure. The pore space was formed by pores located between carbon fibers.

A correspondence in the distribution of such elements as carbon, oxygen, sulfur and gold was recorded by element EDS and WDS mapping of the CBCS sample after contact with a gold-containing solution. A similar distribution patterns of carbon and oxygen can be explained by the presence of C_xO_y complexes formed on the sorbent surface during its activation [2]. The identical nature of the distribution of sulfur and gold may indicate the sorption of gold in the form of [Au(S)₂]⁻ complexes. The latter were most likely formed during the leaching of gold from ore, since the sulfur concentration in the special coke fines-based sorbent is insignificant [1], and it cannot affect the sorption process [2].

According to results of EDS and WDS mapping by elements of the RHp-850VA sample after contact with production rhenium-containing solution, rhenium ions were on the carbon fiber surface. Element EDS mapping showed a great compliance between distribution patterns of oxygen and rhenium and iodine and rhenium. The distribution of other elements (chlorine, sulfur) was not associated with the carbon surface. They were present on carbon surface and filled the pore space as well. But element WDS mapping, as more sensitive method, confirmed an absolute accordance between distribution patterns of oxygen and rhenium. This fact suggests that rhenium is distributed on the carbon fiber surface in combination with oxygen obviously in the form of ReO₄^-1 although Re₂I₈^-2 clusters can be present as well. 

The obtained results on the distribution of gold and rhenium ions on the surface of special coke fines- and rice husk-based sorbents indicate the interaction between adsorbates and functional groups active in relation to them. Ion exchange processes may occur. These findings are required to be confirmed by other research methods.

This study is funded by the Science Committee of the Ministry of Science and Higher Education of the Republic of Kazakhstan (grant number AP 19677767).

The pyrometallurgical production of nonferrous metals such as copper and nickel heavily depends on magnesia-chrome refractory linings. Over the course of their service life, these refractories become infiltrated by molten phases containing not only copper or nickel but also associated metals such as cobalt, lead, tin, and zinc. Depending on the process step from which the refractory material originates, they can also be infiltrated by oxide melts (slag) or sulphide melts (matte). Currently, most spent refractories are disposed of in landfills. However, in the context of resource efficiency and sustainability, there is increasing interest in exploring these waste materials as potential secondary resources. This study investigates spent magnesia-chrome refractories focusing on the recovery potential of the infiltrated metals as well as the refractory material itself. Through detailed characterization and laboratory-scale experiments, the research outlines potential separation and recovery strategies, highlighting both opportunities and challenges associated with their practical implementation.

Deep slag recovery is a critical process in the metallurgical industry to extract valuable metals from slag waste. Current literature indicates a significant knowledge gap regarding the deep reduction of slags under extremely low partial pressures of oxygen, approximately P_O2<10^-10 atm [1-3].

This study aims to explore the factors influencing the efficiency of metal recovery from slag, particularly focusing on the chemical composition of slag, temperature, and oxygen partial pressure [4-5]. The goal is to optimize recovery processes to enhance efficiency and reduce costs.

The research involved experimental melting of slag samples under controlled conditions, simulating autogenous melting and purging with oxygen-containing mixtures. Various analytical techniques, including X-ray phase analysis, thermal analysis, and SEM analysis, were employed to evaluate the composition and properties of the slag.

The findings demonstrate that achieving deeply reducing conditions significantly impacts the recovery of metals, particularly copper, from slag. The study reveals that the copper content can decrease from 0,93-1,54% to 0.43-0.80% after reduction treatment, highlighting the importance of controlling oxygen partial pressure and temperature during the process. Optimal conditions for reducing depletion of slags were identified, indicating a temperature of 1300 °C and a need for substantial heat input to facilitate effective reduction reactions.