The steelmaking industry requires coke as a reducing agent, as an energy source, and for its ability to hold slag in a blast furnace. Coking coal as raw coke material is very limited. Studying the use of biomass as a mixture of coking coal in the synthesis of biocoke is necessary to reduce greenhouse gas coal emissions. This research focuses on biomass and heating temperature through the coal blending method to produce biocoke with optimal mechanical properties for the blast-furnace standard. The heating temperature of biomass to biochar was evaluated at 400, 500, and 600 °C. The blending of coking coal with biochar was in the compositions of 95:5, 85:15, and 75:25 wt.%. A compacting force of 20 MPa was employed to produce biocoke that was 50 mm in diameter and 27 mm thick using a hot cylinder dye. The green sample was heated at 1100 °C for 4 h, followed by quenching with a water medium, resulting in dense samples. Increasing heating temperature is generally directly proportional to an increase in fixed carbon and calorific value. Biocoke that meets several blast-furnace criteria is a coal mixture with coconut-shell charcoal of 85:15 wt.%. Carbonization at 500 °C, yielding fixed carbon, calorific value, and compressive strength, was achieved at 89.02 ± 0.11%; 29.681 ± 0.46 MJ/kg, and 6.53 ± 0.4 MPa, respectively. This product meets several criteria for blast-furnace applications, with CRI 29.8 and CSR 55.1.

No abstract

Magnesium in nature can be found in the form of minerals and seawater. Bittern is a sea-salt industry by-product that contains magnesium and potassium salts. Usually, bittern is discharged back to the sea, even though bittern can be further processed to obtain magnesium contained in it. Magnesium oxide (MgO) nanoparticles can be used in a variety of applications because of their good surface recreation properties. In this study, precipitation of Mg2 + ions from bitterns was carried out using sodium hydroxide to produce magnesium hydroxide. Then, it was calcined and went through sonochemical process to produce nano magnesium oxide. Sonication time and amplitude were used as variables. Sample with sonication time of 16 minutes and amplitude of 30% has the smallest particles with an average diameter of 195.7 nanometers.

Electromagnetic waves show rapid development in electronics, telecommunications, and the military. One of the efforts to overcome the effects of electromagnetic interference is by developing microwave-absorbing materials. Barium hexaferrite is the best candidate for development as an absorber material. Microwave absorption in barium hexaferrite can be increased through Mg-Al doping and reducing the particle size. This study aimed to analyze sonication parameters to reduce the particle size by combining destruction methods using mechanical alloying followed by high-power ultrasonic irradiation. Barium hexaferrite was synthesized through mechanical alloying by mixing stoichiometric BaCO3, Fe2O3, Al2O3, and MgO (Sigma-Aldrich p.a 99%) (Mg-Al 0.4%wt). The samples continued the sintering process at 1200 °C for 2 h to grow crystal embryos. The optimal parameters for ultrasonic destruction were using a transducer:reactor diameter ratio of 1:10, a particle density of 5 g/250 mL, and adding a non-ionic surfactant of 0.01% at an amplitude of 55% and a sonication time of 8 h. These methods resulted in the saturation magnetization of 18.50 emu/g and a coercivity of 0.08 Tesla. The reduction in the particle size of BHF doped with Mg-Al was successfully up to 21 nm, resulting in a reflection loss of up to −40.8697 dB at 11.896 GHz (x-band, 8–12 GHz). The BHF nanoparticles doped with Mg-Al effectively absorbed up to 99.99% electromagnetic waves.

Barium hexaferrite (BHF) with the chemical formula BaFe12O19 is a well-known permanent magnet and is still primarily used in various electrical devices. Because of its excellent magnetic properties, BHF is potentially one of the best candidates as a microwave absorber. For this investigation, the magnetic and microwave absorption characteristics of nanostructured BHF and BaFe9Mn1.5Ti1.5O19 were study. The high coercivity of BHF was substantially reduced through Mn-Ti partial substitution for Fe atoms with a minor reduction of its saturation magnetization. Nanostructured Mn-Ti-doped BHF was obtained through particle size reduction with high-powered ultrasonic irradiation. After 12 h of ultrasonic irradiation, the mean particle of BHF reduced to 61 nm from 380 nm, and the Mn-Ti-doped BHF reduced from 545 nm to 95 nm. The mean crystallite size of the two samples was 15 and 18 nm, respectively. Hence, the particles of both samples contained only a few crystallites. The characterization of reflection loss revealed that the highest absorption value achieved by the nanostructured BaFe9Mn1.5Ti1.5O19 sample was 19.75 dB at 13.6 GHz, and approximately 90% of the intensity of incoming electromagnetic waves was reduced by the material.