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In the present work, the effect of dephosphorization slag basicity on the dephosphorization of hot metal has been studied in the lower temperature range of 1370 °C to 1420 °C and the lower basicity of 1.26 to 2.20 with new double slag converter steelmaking process (NDSP). Based on the ion-molecule coexistence theory (IMCT), the thermodynamic model IMCT-Ni of dephosphorization slag is established. With increasing basicity from 1.26 to 2.20, the phosphorus distribution ratio LP between hot metal and slag increases. The dephosphorization ratio and the decarbonization ratio both increase, while the demanganization ratio decreases. The morphologies of P-rich phase change from long strip shape (B = 1.26-1.37) to dendritic shape (B = 1.50) and to massive shape (B = 1.71-2.20). The area of P-rich phase increases from about 4 μm2 to about 8000 μm2. The content of P2O5 in the P-rich phase increases and the value of the coefficient n in nC2S-C3P of the P-rich phase decreases from 6-20 to 1-2. The phosphorus-enrichment contribution ratio of calcium silicate is in the order of RC2S>RCS>RC3S>RC3S2. The phosphorus-enrichment degree in dephosphorization slag is enhanced mainly by C2S-C3P. With increasing basicity, the calculated results of IMCT-(pct C2S-CjP) and RC2S are well consistent with the measurement results of AP-rich phase and (pct P2O5)P-rich phase of industrial experiment, indicating that the IMCT calculated results can correctly express the phosphorus-enrichment degree of dephosphorization slag.

Examining the kinetics involved in the Argon Oxygen Decarburization (AOD) process, especially in the hotspot and emulsion zones within distinct reactors, can offer a deeper understanding of the refining mechanism in stainless-steelmaking. A predictive dynamic model has been formulated to estimate the effects of different refining processes, encompassing decarburization, desiliconization, demanganization, and chromium removal. The model includes a sub-model for heat loss calculation. The FactSage™ software, along with its macro programming capability, was utilized to incorporate thermochemical and kinetic information into the model. The model forecasts that the predominant chromium removal occurs within the hotspot zone, while carbon, silicon, and manganese removals occur in both the hotspot and emulsion zones. The predictions regarding the transient compositions of steel and slag, as well as the temperature of the steel bath, align with the plant data (Average of five heats), showcasing consistency.

In this work, the kinetics of decarburization and demanganization of Fe–15Mn–1C alloy by bubbling mixtures of Ar–O2 into the melt at 1823 K was studied. Experiments were conducted at total gas flow rates of 200 and 300 Nml/min and gas mixtures of Ar containing 6.7 to 20 pct O2. Increasing the gas flow rate and oxygen in the gas mixture resulted in higher overall rates of decarburization and demanganization. However, the experiments with the lowest oxygen concentration were the most efficient in terms of oxygen utilization for decarburization. The ratio of manganese loss to decarburization was found to be controlled by the relative mass transport of manganese and carbon in the metal. Based on the estimated mass transfer coefficient for either carbon or manganese, the reaction time for each bubble was estimated to be 0.001 seconds which is about 1 pct of the residence time of the bubble in the liquid. Although the initial competition for oxygen between manganese and carbon was controlled by relative mass transport rates, this work found no evidence that manganese and carbon repartitioned towards the equilibrium over the remaining lifetime of the bubble.

In the present study, a modified duplex melting process was set up so as to be able to produce an EN-GJL-150 gray cast iron from a local manganese-rich pig iron. A descriptive statistics showed an average Mn and Si content in raw material such that: Mn % = 2.457±0.133 and Si % = 0.682±0.088. The demanganization process was run and monitored in a cascade of two industrial-scale furnaces: a rotary kiln and an electric arc furnace. The performed experiments indicated that: 1) the manganese content decreased from 2.45 % to 0.94 %, 2) the manganese oxidation obeys the first order kinetic model, 3) Brinell and Rockwell hardness’s decreased by 38.83% and 27.81% respectively, and 4) the produced cast iron has a pearlitic microstructure with a small fraction of ferrite (1 to 5%) in the matrix and traces of cementite. All results showed that the produced castings comply with the standards in force for EN-GJL-150 cast irons, similar to gray cast iron ASTM A48 Class 20.

Dry as well as wet coating techniques were developed to coat glass beads as filter media to remove manganese from water. For dry coating, powdered manganese oxide ore was fixed on the media surface. Wet coating was achieved by depositing synthetic manganese oxides onto the bead surface. The media were characterized by electron microscopy as well as by testing the removal of Mn2+ in a continuous stirred tank reactor. Image analysis of microscopic pictures illustrated that the surface area could partly be coated by powdered material using dry coating methods, whereas complete coverage was achieved using wet coating approaches. With regard to dry coating techniques, Mn sorption uptake was higher for the adhesively dry coated glass beads than for beads where a binding agent was used. The wet coating column approach proved to be more successful than the coating of beads in a stirred tank reactor. Mn removal capability of the beads increased with higher reactant concentrations during coating. Oxide-coated glass beads applied in filter systems have the potential to improve conventional demanganization processes.

The aim of the study is the analysis of the possible use of ion-exchange demanganization of drinking water in the Oktyabrsky District of the Jewish Autonomous Region to reduce the concentration of manganese to a value below MPC. For the ion-exchange demanganization of drinking water, a domestically-produced KU-2-8 ES cation exchanger and an imported Purolit C120 E cation exchanger were used as adsorbents. We used four different methods, reproducing purification with drinking filters in domestic conditions. We have determined that among 33 analyzed water samples, 16 of them, which were combined into groups No. 2 and No. 4, exceeded the MPC value for gross manganese. This fact indicates that these waters require treatment and conditioning for drinking purposes. We have revealed the ranges of concentrations for indicators of the physiological relevance of water: the total hardness is 1.5-7 meq / dm3, the calcium content is 25-130 mg / dm3, and the magnesium content is 5-65 mg / dm3. This fact indicates that the concentrations of calcium and magnesium, as well as the total hardness in the water, are below the lower limits of their physiologically relevant concentrations in drinking water.

The demanganization reaction kinetics of carbon-saturated liquid iron with an eight-component slag consisting of CaO–SiO 2 –MgO–FeO–MnO–Al 2 O 3 –TiO 2 –CaF 2 was investigated at 1553, 1623, and 1673 K in this study. The rate-controlling step (RCS) for the demanganization reaction with regard to the hot metal pretreatment conditions was studied via kinetics analysis based on the fundamental equation of heterogeneous reaction kinetics. From the temperature dependence of the mass transfer coefficient of a transition-metal oxide (MnO), the apparent activation energy of the demanganization reaction was estimated to be 189.46 kJ·mol –1 in the current study, which indicated that the mass transfer of MnO in the molten slag controlled the overall rate of the demanganization reaction. The calculated apparent activation energy was slightly lower than the values reported in the literature for mass transfer in a slag phase. This difference was attributed to an increase in the “specific reaction interface” (SRI) value, either as a result of turbulence at the reaction interface or a decrease of the absolute amount of slag phase during sampling, and to the addition of calcium fluoride to the slag.