Distribution of boron between oxide slag and steel

The influence of silicon (0.1–0.8%), aluminum (0.005%), and carbon (0.1%) in steel on the reduction of boron from slag (basicity 5) at 1400–1700°C is studied by thermodynamic analysis on the basis of HSC 6.1 Chemistry software (Outokumpu). Experiments on the boron distribution between CaO–SiO₂–MgO–Al₂O₃–B₂O₃ slag and steel are conducted in a high-temperature Tamman resistance furnace. Low-carbon steel with different silicon content is employed. According to the thermodynamic modeling and the experiments, direct microalloying of steel with boron is possible on the basis of its reduction by the silicon present in the steel. The reduction of boron from slag by silicon is theoretically analyzed and experimentally confirmed. The results of thermodynamic modeling indicate that boron may be reduced from CaO–SiO₂–MgO–Al₂O₃–B₂O₃ slag by silicon despite its low content in the steel (0.1–0.8%). With increase in the initial Si content in the steel, the boron concentration in the steel also increases. The influence of the Si content and the steel temperature on the final boron content is studied. When steel is held under slag containing 4.3% B₂O₃, the boron is reduced, mainly by silicon, whose content in the steel is 15–22% lower after the experiment. More boron is present in the steel sample with an elevated Si content. The degree of assimilation of boron is 5.8–6.9%; this is consistent with the thermodynamic modeling. The boron content in the metal may be regulated by adjusting the temperature and the silicon content of the steel. On the basis of the results, a technology for the direct microalloying of steel with boron may be developed.     

Calculations of manganese ferroalloys production efficiency from different ores

The cost of producing manganese alloys by reduction from manganese ore using carbothermic process is estimated. Alternatives of FeMn78 and SiMn17 production from rich Australian manganese ore with low-phosphorus concentration or low-phosphorus manganese slag in charge mixture with poor domestic Russian ore with comparatively high phosphorus content are calculated and presented in the article. Direct production costs for alternative variants in a wide range of cherge composition are estimated.     

Improved manganese extraction in the production of manganese ferroalloys

In the production of manganese ferroalloys from ore, about 50% of the manganese in the ore is lost. The manganese lost with the enrichment-slag tailings may be returned to the production of manganese ferroalloys by dithionate method of enrichment of the slurries. A technology is developed for the production of high-carbon ferromanganese from concentrate obtained by the chemical enrichment of tailings slurries. Low-phosphorus Mn slag is used in the production of ferrosilicomanganese and refined manganese ferroalloys. A method is described for alloying hot metal with manganese from slag during the production of lowand medium-carbon ferromanganese. Processes are developed for the production of medium-carbon ferromanganese by mixing ore–limestone melt with high-carbon ferromanganese and removing the phosphorus from Mn-bearing melts by bubbling with CO. The degree of phosphorus removal (70–90%) depends on the bubbling time. By means of improved production of manganese ferroalloys and extraction of manganese from slag and slurries, the manganese extraction may be significantly increased.     

Solid-phase carbothermic reduction of the components of chrome-iron ore raw materials

The procedure and results of laboratory studies of the solid-phase reduction of chromium and iron from chrome-iron ore raw materials are presented.     

Ferroalloy production in Russia

Russian production and demand for ferroalloys are considered. The main ferroalloy producers are noted. The volume of imports and exports and the apparent demand for the main Russian ferroalloys between 1990 and 2014 are detailed. The change in the structure of ferroalloy production, globally and in Russia, is outlined. Priorities for the Russian ferroalloy industry in order to improve global and domestic competitiveness are recommended.     

The Choice of Selective Agents for Extractive Distillation by Gas–Liquid Chromatography

Data on the selectivity in the case of infinite dilution obtained using gas–liquid chromatography have been analyzed for seven industrial separating agents. Selective agents for the extractive distillation of binary systems of various types have been recommended.     

Composition and performance of chromium-bearing ferroalloys

Experimental data on the composition, melting point, and density are presented for chromium-bearing ferroalloys: ferrochrome, ferrosilicochrome, and ferrochromomanganosilicon. The best compositions are determined for these ferroalloys.     

Thermodynamics of interaction between sulfite-thiosulfate solutions and noble metals

The thermodynamic probability of dissolution of noble metals in aqueous solutions of sodium thiosulfate, sodium sulfite, and their mixture under standard conditions (without heating of the solution) is considered. The influence of impurities and catalysts (divalent copper, elemental sulfur, oxygen access into the solution, and ammonia) is evaluated. Theoretical calculations of reaction rates are performed. As a result of theoretical investigations, a conclusion about the usefulness of applying sulfite-thiosulfate solvents of noble metals from ores and concentrates is made.