Garnet Chemical Zoning Based Thermobarometry: Method Evaluation and Applications in the Menderes Massif, Western Turkey

The garnet chemical zoning method (GZM) is a reliable thermodynamic approach for forward modeling pressure-temperature (P-T) paths using observed garnet and bulk rock compositions. However, intracrystalline diffusion is known to compromise the integrity of GZM modeled garnet-growth P-T paths. For this reason, extracting reliable metamorphic estimates from garnet-bearing schists in the Central Menderes Massif (CMM), western Turkey, has been difficult. To evaluate the impact of diffusion on GZM, we simulate garnet growth and diffusion for an average metapelite using the program Theria_G. Modeled garnet compositions from four simulations are used to estimate P-T conditions and paths by GZM, which are compared against Theria_G specified P-T-t trajectories. Factors influencing results are heating/cooling rate, grain size, and peak T. At a maximum T of 610 °C, both undiffused and diffused garnet compositions returned estimates comparable to prescribed conditions regardless of heating/cooling rate. Diffused profiles from simulations reaching a maximum T of 670 °C also reproduced prescribed P-T paths if tectonism occurred at high heating/cooling rates (50 °C/my). From these insights and additional Theria_G simulation-derived observations for CMM garnets, we deduce that metamorphism in the region exceeded 650 °C and achieved a maximum burial P between 8–10 kbar prior to Cenozoic exhumation.

The Mechanism of Joint Reduction of MoO3 and CuO by Combined Mg/C Reducer at High Heating Rates

Understanding of the decisive role of non-isothermal treatment on the interaction mechanism and kinetics of the MoO3-CuO-Mg-C system is highly relevant for the elaboration of optimal conditions at obtaining Mo-Cu composite powder in the combustion processes. The reduction pathway of copper and molybdenum oxides with combined Mg + C reducing agents at high heating rates from 100 to 5200 K min−1 was delivered. In particular the sequence of the reactions in all the studied binary, ternary and quaternary systems contemporaneously demonstrating the effect of the heating rate on products’ phase composition and microstructure was elucidated. The combination of two highly exothermic and speedy reactions (MoO3 + 3Mg and CuO + Mg vs. MoO3 + CuO + 4Mg) led to a slow interaction with weak self-heating (dysynergistic effect) due to a change in the reaction mechanism. Furthermore, it has been shown that upon the simultaneous utilization of the Mg and C reducing agents, the process initiates exclusively with carbothermic reduction, and at relatively high temperatures it continues with magnesiothermic reaction. The effective activation energy values of the magnesiothermic stages of the studied reactions were determined by Kissinger isoconversional method.

DEFROSTING OF ANIMAL COLOSTRUM IN A RING RESONATOR OF ULTRA-HIGH FREQUENCY INSTALLATION

The article is devoted to the development of a two-resonator ultra-high-frequency (UHF) installation for defrosting and warming up animal colostrum, which ensures electromagnetic safety during continuous operation. As well as the development and study of the parameters of a microwave installation, which allows defrosting and uniformly warming up colostrum of animals in the field of a standing wave in the electromagnetic field of a traveling wave. A microwave installation is described with working chambers arranged in tiers in the form of an annular and conical resonators, containing, respectively, dielectric containers and dielectric conical plates. The out-of-limit waveguide is calculated and the radiation of the electric field through the loading hole is considered in the absence of the out-of-limit waveguide at a distance from the ring resonator that is greater than the wavelength. For uniform defrosting of colostrum in plastic bottles, they should be moved in a ring resonator and the magnetrons should be positioned with a shift of 120 degrees around the perimeter. Then the resulting strength of the electric field consisting of several initial fields will be equal to the vector sum of their strengths. To achieve a high heating rate of raw materials in the region of positive temperatures, it is necessary to provide a condition for heating a thin layer of liquid with the help of coaxially located conical dielectric trays

ANALISIS NILAI KALOR DAN LAJU PEMBAKARAN BRIKET TONGKOL JAGUNG SEBAGAI SUMBER ENERGI ALTERNATIF

ABSTRAKTujuan dari penelitian ini yaitu untuk menghasilkan briket tongkol jagung sebagai alternative sumber energi yang memiliki nilai kalor yang tinggi. Briket tongkol jagung dibuat dari tongkol jagung yang sudah dikeringkan dan dihaluskan sebelumnya dengan ukuran 20 mesh. Masing-masing perlakuan dicetak dengan variasi persentase perekat tepung tapioka yaitu 5%, 10%, dan 15%. Selain variasi perekat dilakukan juga variasi tekanan pembentukannya untuk melihat komposisi terbaik yang menghasilkan nilai kalor yang tinggi dan laju pembakaran yang sesuai. Briket selanjutnya diuji nilai kalor dan laju pembakarannya dengan menggunakan alat bom calorimeter. Hasil penelitian menunjukkan bahwa secara berturut-turut nilai kalor dan laju pembakaran briket dengan persentase komposisi perekat 5%, 10%, 15% yaitu 21,00 kJ, 22,68 kJ, 31,08 kJ, dan 12,00 gram/menit, 13,33 gram/menit, 13,50 gram/menit. Hasil terbaik dihasilkan pada komposisi persentase perekat 15% dengan nilai kalor mencapai 31,08 kJ, dan laju pembakaran 13,50 gram/menit yang tidak terlalu jauh meningkat dibandingkan dengan komposisi persentase perekat lainnya. Kata kunci: briket; tongkol jagung; nilai kalor; laju pembakaran ABSTRACTThe purpose of this research is to produce corn cobs briquettes as an alternative energy source that has a high calorific value. Corn cobs briquettes are made from corn cobs that have been dried and previously mashed with a size of 20 mesh. Each treatment was printed with variations in the percentage of tapioca starch adhesive, namely 5%, 10%, and 15%. In addition to variations of the adhesive, variations in the formation pressure were also carried out to see the best composition that produced a high heating value and an appropriate combustion rate. The briquettes were then tested for calorific value and rate of combustion using a bomb calorimeter. The results showed that the calorific value and burning rate of briquettes with the percentage of adhesive composition 5%, 10%, 15%, were 21.00 kJ, 22.68 kJ, 31.08 kJ, and 12.00 gram/minute, respectively. 13.33 grams/minute, 13.50 grams/minute. The best results were obtained at 15% adhesive percentage composition with a calorific value of 31.08 kJ, and a burning rate of 13.50 gram/minute which was not significantly increased compared to other adhesive percentage compositions. Keywords: briquettes; corn cobs; calorific value; combustion rate

Study of making coal water slurry with lignite Pendopo coal

The Coal Water Slurry (CWS) technology increases the calorific value and changes the phase of coal from solid to liquid. The CWS Plant with a coal capacity of 1.4 t/hour located at Karawang, West Java converts lignite coal to CWS. Coal undergoes pulverizing, upgrading, and slurry-making processes to become CWS. Pulverization is the process of refining coal size into 200 mesh. The upgrading process is through reducing the moisture content in heat exchangers (HE). It occurs in HE where the coal is pressurized to 15 MPa and the temperature is maintained at 330 0C for 30 minutes. The research objective was to determine the CWS characteristics of the South Sumatra Pendopo lignite coal. The method used is through testing where the Pendopo coal is converted into CWS at the CWS Plant. The result shows that Pendopo coal which has a heating value of High Heating Value (HHV) 2,725.00 kCal/kg As Received (AR) has an increase in HHV heating value of 3,218.00 kcal/kg AR when it becomes CWS. The total moisture content of Pendopo coal has decreased from 49.36% to 44.58% when it becomes CWS. The fixed carbon content of Pendopo coal increased from 19.78% AR to 24.01% AR.