CaO Compounds Research Articles

The geoecological analysis of Lake Tuchne (Volyn Polissia) and assessment of sapropel reserves in it


 
 
 The administrative-territorial reform in Ukraine, which began in 2015, opened up prospects for newly created territorial communities to determine the resource potential of local territories under control and develop strategies for balanced nature use and their progressive development. The lakes, which have a significant potential for sapropel resources, take an important place in the Polissia region of Ukraine. Given the above, there is a need for a comprehensive study of specific lakes and justification of recommendations for the rational use and protection of their water and sapropel resources. The object of our research is Lake Tuchne, Volyn Polissia. The catchment area of Lake Tuchne is 10.05 km2, and the reservoir itself is 0.39 km2. A bathymetric model of the lake was built with a depth interval of 0.5 m. The vegetation index (NDVI) for the reservoir over the past five years has been varying from -0.53 (12/02/2021) to +0.48 (07/15/2021). The research presents a stratigraphic section of the reservoir sediments. The area of accumulated sapropel is 20.5 hectares, the average thickness is 4.46 m, and the maximum is 10.0 m. The ash content of sapropel varies within 17.5-37.5% (on dry substance). The content of Fe2O3 in the core ranges from 2.53% to 7.26%. The distribution of CaO compounds in the samples ranges from 2.09 to 8.12%. The CO2 content varies from 1.97 to 9.72%. The concentration of Р2О5 in sapropel samples is 0.19-0.53%. The distribution of S in sapropel deposits ranges from 0.23 to 1.09%. The pH (salt extract) distribution in the core samples varies from moderately alkaline (7.63) to close to neutral – 5.97. A digital landscape map of the lake was constructed with the selection of the littoral and sublittoral-profundal aqua sub-areas and five types of aquafacies. A landscape-metric analysis of the natural and aquatic complex of the lake was carried out. The potential of water resources of Tuchne lake is 827.0 thousand m3. Sapropel reserves of category A are 914,000 m3, and based on a conditional 60.0% humidity, they are 155,000 tons. The species composition of sapropel is represented by zoogenic, organo-ferrous, and organo-limestone species. The total stock of sapropel in the lake basin is 52.5% of its volume. The reservoir is promising for extracting sapropel due to its quality characteristics and hydro-technical prerequisites for operation. Mined sapropel can be used in agriculture, medicine, recreation, etc. Implementing this task will improve the geoecological state of the lake and the quality of its water resources.
 
 

Studying on mineralogical and petrological characteristics of Gara Djebilet oolitic iron ore, Tindouf (Algeria)

Demand for iron ore worldwide has been steadily increasing which leads to the extraction of iron ore deposits with more complex mineralogies and higher levels of silicon and phosphorus impurities. This is the case in Algeria with the iron ore deposit of Gara Djebilet, Tindouf; where it has recently been exploited to ensure the sufficiency of iron ore required to produce iron and steel products. This deposit has remained unexploited for several decades due to inadequate knowledge of its mineralogy, treatment, and economic assessments. The aim of this study is to find out the microstructure, chemical composition, and mineralogical distribution of valuable minerals and impurities, to understand the efficient processing methods for this specific iron ore. The characterization of representative ironstone samples taken from the studied area was carried out using optical microscopy, X-ray fluorescence spectrometer (XRF), petrographic microscope, X-ray diffractometer (XRD), and scanning electron microscope (SEM) coupled with energy dispersive X-ray spectroscopy (EDS). The results of the mineralogical analyses confirmed that it is an oolitic fine-grained ore consisting of gangue minerals principally composed of quartz, apatite, and iron-rich concentric cored structures. Chemical analyses of the ore indicate that it contains 56.58 wt% Fe with 7.98 wt% SiO2, 7.09 wt% Al2O3, and minor amounts of P2O5, CaO, MgO, and TiO2 compounds. The phosphorus associated was present in both ooids and groundmass, indicating that the ore has a complex texture with very rich and diverse mineralogy. For that, two potential scenarios were proposed for processing of the studied iron ore.

Mineralogical and geochemical characterization of the Wonosari formation limestone at Gunungkidul Indonesia as preliminary investigation of Portland cement raw material

Mineralogical and geochemical investigations were carried out to determine the characteristics of limestone in the Wonosari Formation and to suggest its depositional environment and a preliminary study for the properties of Portland Cement. The study was conducted at Ponjong Area, Gunungkidul Regency, Daerah Istimewa Yogyakarta, Indonesia. The outcrop in this study area is composed of Wonosari layered limestone. Based on the facies interpretation in the research area, there are three depositional units: packstone, wackstone, and grainstone. This area’s depositional environment is the back reef lagoon and sand apron zones that are not related to the open sea. According to XRF data, limestone showed a reasonably high composition of CaO compounds, about 53.78% - 59.09%. Most limestone samples were classified as good quality as Portland Cement Raw Material due to CaO content >49%. The MgO, SiO2, Al2O3, Fe2O3, SO3, K2O, Na2O, TiO2, and P2O5 compounds also fulfil the Indonesian National Standard (SNI-15-2049-2004). Geochemical content shows limestone has a higher grain percentage than the matrix. The utilization of limestone in research area are expected to be a reference for the development of natural resources in the future that pay attention to the environment for mutual sustainability.

Oxide ceramic coatings with amorphous/nano-crystalline dual-structures prepared by micro-arc oxidation on Ti–Nb–Zr medium entropy alloy surfaces for biomedical applications

Due to the presence of multi-principal elements, the multi-principal element alloys (MPEAs) are supposed to undergo competing oxidation reactions during micro-arc oxidation (MAO). In this work, Ti–Nb–Zr medium entropy alloy (MEA, MAO-Free) was MAO-treated at various applied voltage. For Ti–Nb–Zr MEA treated at 250 V (MAO-250 V), the coating microstructure was characterized by amorphous oxides of Ti, Nb and Zr from the substrate and amorphous compounds of CaO, Ca(OH)2, SiO2 and CaSiO3 from the electrolyte, which distributed homogeneously in coating matrix. Different from the microstructure of MAO-250 V group, tetragonal-ZrO2 nano-crystals dispersed in amorphous coating matrix were noticed for that treated at 300 V (MAO-300 V). For specimen treated at 350 V (MAO-350 V), the coating matrix exhibited higher crystallinity by composing of major tetragonal-ZrO2 and minor rutile-TiO2, with the presence of nano-sized amorphous regions. The pore size, porosity, surface roughness and hydrophilicity of coatings increased with the increase of applied voltage. An order of MAO-300 V > MAO-250 V > MAO-Free > MAO-350 V group was identified for the wear resistance. Moreover, the MAOed coatings exhibited comparable corrosion resistance and cyto-compatibility to MAO-Free group. Together, the results indicate that the MAO-300 V group with favorable wear resistance, corrosion resistance and cyto-compatibility is promising for biomedical applications.

Effects of substituting municipal waste incineration fly ash for lime on generating a bonding phase during the sintering process

As the main solid by-product of municipal waste incineration, the safe treatment and resource utilization of municipal waste incineration fly ash (hereafter referred to as fly ash), comprising a large amount of CaO, SiO2, Al2O3, and related compounds, has become an exceedingly important environmental concern. Owing to its alkaline composition, herein we propose that fly ash replaces lime as a part of the flux used in the sinter process. Following a combined approach using thermodynamic calculations and experimental verification, we found that CaO from fly ash can combine with Fe2O3 to form complex calcium ferrite, which can effectively replace lime to form the binder phase for the sintering process. In addition, a small amount of Al2O3 impurities present in fly ash promotes the formation of acicular calcium ferrite with an interwoven structure, which improves the reducibility and mechanical strength of the sintered ore. However, when the proportion of fly ash replacing lime is too high and results in an Al2O3 content greater than 2%, the acicular calcium ferrite is transformed to the plate state, which deteriorates the metallurgical properties of the sintered ore. Furthermore, alkaline metal chlorides (e.g., KCl and NaCl) present in fly ash can improve the dissolution of Al2O3 and SiO2 in silicate, which impedes the performance of the binder phase. However, most of the alkali metal chlorides are volatilized, and only a small amount remains in the form of oxides, which have little effect on the performance of the sintered binder phase. Overall, the best metallurgical properties were obtained when fly ash replaced 25% lime as the sintering alkaline flux. Therefore, replacing lime with fly ash to form the binder phase during sintering holds excellent application prospects.

Deep learning interatomic potential for Ca-O system at high pressure

Calcium-containing oxides are fundamental components of the Earth's crust and mantle. Analysis of their structural behavior contributes to our understanding of the Earth's interior, which needs a reliable interatomic potential. Here, we present an interatomic potential for the Ca-O system using the deep neural network method. The initial training data set for the deep interatomic potential (DP) consists of snapshots of prototype binary structures from materials projects and crystal-derived structures based on Ca-O binary compounds, as well as their molecular dynamic trajectories. The accuracy of the DP is evaluated by predicting forces and energies in comparison with those from ab initio calculations. We demonstrate that the vibrational and thermodynamic properties based on DP calculations are in excellent agreement with those from ab initio calculations. Besides, we also construct a temperature-pressure phase diagram of Ca-O compounds with DP at a lower cost compared to ab initio methods. Finally, we use the DP to explore Ca-O structures by combining it with the genetic algorithm, the accuracy of which is validated by a principal component analysis for the local atomic environments. The DP training procedure used in this work is equally applicable to other systems for accurate atomistic simulations as an effective method.

Use of dolomite catalyst in biodiesel production via transesterification of waste cooking oil in oscillatory baffled reactor

AbstractBiodiesel has recently gained popularity due to its environmental issues and the fact that it is generated from renewable resources. However, the cost of the synthesis of biodiesel is the major impediment to commercialization. The utilization of leftover cooking oils as raw material, the adaptation of a continuous transesterification process, and the use of cheap catalysts are the major possibilities for investigating the cost of biodiesel. In this work, a dolomite catalyst was prepared from natural dolomite rocks and used for the evaluation of continuous transesterification of biodiesel from oleic acid as a model compound of waste cooking oil (WCO). The dolomite catalyst was prepared by activation under vacuum at a surface area of 34.5 m2/g. The characterization tests showed good thermal stability of the catalyst and evolution of the CaO and MgO compounds at high concentrations. A kinetic study was conducted to obtain kinetic parameters of catalytic transesterification of the WCO. The kinetic experiments were carried out at 298–333 K, and residence time up to 80 min. The results presented that the catalytic transesterification is the first‐order reaction, and the activation energy was 43 kJ/mol. The oscillatory baffled reactor (OBR) was used to evaluate the dolomite catalyst for the continuous production of biodiesel via transesterification. The evaluation study was conducted at a methanol: oil mole ratio of 6:1 and the effect of different operation variables on oleic acid conversion to biodiesel was studied. These variables were temperature (323, 333, and 343 K), residence times (5–40 min), the amplitude of oscillation (2–8 mm), and frequency of oscillation (1, 2, 3, 4, and 4.3 Hz). The results showed an outstanding performance and stable activity of the dolomite catalyst as a conversion of 96% was obtained at 333 K, 4.3 Hz, 8 mm amplitude, and 40 min residence time.

Elemental characterization of quartzite of Pouma sub-division of Cameroon and radiation attenuation properties based on XCOM and GEANT4 Monte Carlo simulation

This study used the Energy Dispersive X-Ray Fluorescence (EDXRF) spectrometry to determine the elemental composition of nineteen rock samples from the Pouma sub-division of Cameroon. The major chemical elements found in these samples were compounds of SiO2, Al2O3, K2O, Fe2O3, CaO, and P2O5. The elemental characterization of the investigated samples was used to evaluate the mass attenuation coefficients of the quartzite rocks using the XCOM analytical calculation software and the GEANT4 Monte Carlo computational toolkit. The mass attenuation coefficients were calculated for the average concentration values of the samples from different sampling sites. The mass attenuation coefficients generated using the GEANT4 simulation have uncertainties less than 4% in all the four investigated sampling sites compared to the analytical results. The results of the simulation showed that the calculated mass attenuation coefficients are in good agreement with the theoretical data. Therefore, the developed GEANT4 code for radiation properties assessment of rocks is accurate and could be used by scientists worldwide. The determination of these mass attenuation coefficients is consequently the unveiling of radiation shielding properties of the investigated material.

Granit ve rekristalize kireçtaşı doğal taş atıklarından elde edilen kompozit malzemenin ısıl dönüşümünün incelenmesi

In this study, the usability of granite (magmatic) and recrystallized limestone (metamorphic) natural stone wastes as alternative raw materials in ceramic tile production was investigated. Based on the CaO, SiO2, and Al2O3 compounds found in waste powders, mixtures containing 65% granite and 35% recrystallized limestone (by mass) were prepared to obtain the ceramic phases of gehlenite, wollastonite and anorthite as a result of thermal transformation. The grain size of both raw materials is -149 µm (d90 = 110.957 µm). The first series samples are called natural building stone (DYT), and the second series samples, in which wood chips of 2% (by mass) -1 mm grain size are added to obtain porous material, are called natural building stone - porous (DYT-G). The samples belonging to both series was applied heat treatment at 1,160°C. Phase analysis of samples obtained after heat treatment was measured by X-Ray Diffraction (XRD) and Scanning Electron Microscope (SEM-EDS) methods, and sintering properties were measured using water absorption coefficient, flexural strength, modulus of elasticity, density-porosity and color measurement tests. Gehlenite and wollastonite phases were detected in the heat treated samples, but no anorthite phase was observed. According to the test results, it was determined that the flexural strength (22.64 MPa) of the DYT marked sample was in accordance with the ceramic tile standards. In the DYT-G example, despite the decreasing unit volume mass value, it was determined that the bending strength (16.50 MPa) was in the range of ceramic tile strength values.

Organic modification of precipitated calcium carbonate nanoparticles as filler in LLDPE/CNR blends with the presence of coupling agents: impact strength, thermal, and morphology

This study reports that Precipitated Calcium Carbonate (PCC) nanoparticles from limestone can be modified with oleic acid (OA), which was applied to LLDPE/CNR blends in the presence of the LLDPE-g-OA coupling agent. This study investigates PCC characteristics from limestone that has been modified with OA and its implications of increasing impact strength, thermal properties, and morphology changes in LLDPE/LLDPE-g-OA/CNR/O-PCC composites. Organo-PCC (O-PCC) was prepared by mixing the PCC with OA in n-hexane solvent. The polymer composites were made by mixing LLDPE, LLDPE-g-OA, and CNR simultaneously in an internal mixer at 160 °C with speed rotation of 100 rpm, followed by O-PCC. The characterization results of O-PCC obtained CaO compounds of 97.9%, crystallinity degree of 61.6%, crystals size of 48.6 nm, and scalenohedral-shaped crystals. The results of the impact strength test on LLDPE/LLDPE-g-OA/CNR/O-PCC composites with an O-PCC concentration of 5 wt% showed an increase of 21.5% compared to no fillers. The presence of O-PCC resulted in the thermal properties of polymer composites with a melting point of 125.5 °C and a decomposition temperature of 468.7 °C. The morphology did not result in significant differences in the surface structure after adding O-PCC nanoparticles.

BIODIESEL PRODUCTION OF WASTE COOKING OIL CATALYZED BY CAO DERIVED FROM SNAIL (ACHATINA FULICA) SHELL WASTE

Biodiesel can be production from waste cooking oil catalyzed by base heterogeneous catalysts. One type of heterogeneous base catalyst is CaO. CaO can be produced from mollusc animal waste, one of which is snail shell waste (Achatina fulica). The main constituent of snail shell waste (Achatina fulica) is a calcium oxide compound (CaCO3) which can be decomposed into CaO at high temperatures. In this study, a temperature of 900 oC for 10 hours was used to convert CaCO3 compounds into CaO compounds. Biodiesel production using CaO catalyst on the mole ratio of oil: methanol 1: 6, 3 g weight of catalyst, the reaction temperature at 60 °C, the reaction time of 3.5 hours, and stirring speed of 250 rpm with biodiesel results obtained at 84,28%.

Assessment of Lime Stabilized Soils Modified with Egg Shell Ash for Road Construction

The need to have in-depth knowledge about the Engineering properties of soil and the sub-soil condition for road construction especially in the southwestern Nigeria brought about this study. Some strength properties (California Bearing Ratio (CBR), Compaction, Unconfined Compressive Strength (UCS), and direct Shear tests) of lime stabilized soils modified with Egg Shell Ash (ESA) were assessed. Soil samples were obtained from each state in the study area and transported to the laboratory, where they were stabilized with 6% lime and 0 to 10% ESA before the above-mentioned tests was conducted on them. The local additive was also subjected to a chemical analysis. Results showed that ESA additive has low SiO2 and high CaO compounds. Increase in ESA resulted in increase of all the strength properties (Maximum Dry Density (MDD), CBR, UCS, Cohesion (C), Shear strength (S) and Angle of Internal Friction (ϕ)) and reached peak at 8% ESA, thereafter decrease; albeit, Optimum Moisture Content (OMC) decreases. After the improvement process, almost all the unsuitable soil samples became suitable for use as pavement layer materials. Consequently, a blend of 6% lime and 8% ESA content is recommended for soil improvement, especially for road pavement layers in southwestern Nigeria.

Structural phase transition and electronic structure of binary CaO and SrO under high pressure

We have investigated pressure-induced structural phase transition and electronic structure of binary alkaline-earth monoxides. From our static enthalpy calculations, CaO and SrO are found to undergo a common structural phase transition from B1 to B2 at 59.2 GPa and 32.4 GPa, respectively. B33 phase is found to be meta-stable for both investigated compounds. We have calculated electronic structure with Tran-Blaha modified Becke-Johnson potential (TB-mBJ) potential and the obtained band gaps are improved over standard PBE-GGA functional. CaO and SrO compounds are found to be indirect band gap insulators at ambient pressure. Interestingly, electronic structure calculations at high pressure suggest that B2 phase of CaO is an indirect band gap semiconductor while B2 phase of SrO is a direct band gap semiconductor, i.e., pressure-induced indirect → direct band gap transition is observed in SrO.

Manufacture And Characterization Of Hydroxyapatite From Quail Eggshell Using Precipitation Methods

Abstract — Hydroxyapatite (HA) is a biomaterial used to treat bone defects. The utilization of HA in medicine is currently significantly increased this is because HA has high biocompatibility properties when used as a bone graft. Various kinds of bone grafts from HA are currently available in the market. However, its use is often bumped at a high price and is an imported product. This will ultimately increase the burden of financing that must be borne by hospitals and the government . HA sources can be obtained through extraction from natural products, such as eggshells. The purpose of this study was the creation and characterization of hydroxyapatite from quail egg shells using precipitation methods. The research stage consists of 4 stages, Stage 1 is the calcination of quail egg shells so that CaO compounds are obtained. Stage 2 is the synthesis of HA compounds from CaO compounds produced in the previous stage using wet precipitation or deposition methods. Stage 3 is sintering HA compounds produced in the previous stage using a furnace for five hours at a temperature of 900 o C. Stage 4 is the characterization of the HA compounds produced. The characterization is done using XRD and SEM. Hasil yang diperoleh yaitu Efisiensi dari senyawa HA yang dihasilkan sebesar 52,34%. Based on the characterization carried out using XRD it was obtained that the HA compound was successfully synthesized this is characterized by the peak of the quail eggshell difaktogram that is the same as the peak of the standard HA difractogram which is found at an angle of 2θ: 26.00 o C, 31.90 o C, 32.31 o C, 33.02 o C, 34.19 o C, 46.81 o C, 49.59 o C with the crystal phase and the size of the lattice parameters, namely the lattice a = b = 9.4234 A and c = 6.8801 A. But in addition to the peak of HA there are also other peaks that show the existence of the impurities phase at 2θ : 10.01°, 21.85°, and 53.01°. Based on SEM characterization found that the size of the resulting HA particles is not homogeneous, meaning that there is a difference in the smallest particles with a size of 1,497 μm and there are the largest particles with a size of 60.98 μm. If observed the shape of a single particle tends to be round (Shperical). Thus it was concluded that the manufacture and characterization of hydroxyapatite from quail egg shells using precipitation methods has been successfully carried out. Keywords— hydroxyapatite; quail egg shell; precipitation; bone defects

A Study on Analysis of Sinter Microstructure and Phase Morphology

Sinter is a blast furnace input material obtained by heating to 900-1200 oC without full melting and adhering to each other with superficial melting. It is considered as a multi-phase material with its sinter heterogeneous microstructure. In general, the main mineral phases are hematite, magnetite, silicoferrite of calcium and aluminium (SFCA) and silicates. By determining the SFCA structure in the sinter material, the sintering process will be made more stable and important parameters affecting the quality in the sintering process will be examined. Sinter material obtained from iron ore, iron and steel industry by products and auxiliary materials. The scope of this project is the determination of the amount of SFCA formed by bonding SiO2, CaO, Fe2O3, Al2O3 and MgO compounds and monitoring this value as a parameter by the enterprise. Sinter samples having different characteristic features will be made ready for X-ray diffraction (XRD) and optical microscopy inspections by polishing, etching and freezing in epoxy for mineralogical researches. Before raw data obtained from the analysis is evaluated at Autoquan, they will be converted into Autoquan format and then, they will be read in XRD device and mineralogical composition of the sinter will be revealed by XRD analyses. Detailed view of mineralogical compounds will be investigated so as to complete scanning electron microscope (SEM) analyses and XRD analyses; elemental composition of the compounds and valence conditions of the elements will be researched by energy dispersive spectroscopy (EDS) method. Hematite, magnetite, calcium ferrite phase structures in different formations will be studied subject to melting and temperature during optical microscopy studies conducted on sinter samples. Furthermore, it will be researched variations of SFCA, SFCA-I and SFCA-II phase structures within the sinter matrix subject to different raw material input and process parameters. It will be ensured to interpret the results through rietveld method.

Ab initio based interionic interactions in calcium aluminotitanate oxide melts: structure and diffusion

Calcium aluminotitanate (CaO–Al2O3–TiO2) ternary oxides are of fundamental interest in Materials as well as Earth and environmental science, and a key system for several industrial applications. As their properties at the atomic scale are scarcely known, interionic interactions for the melts are built from a bottom up strategy consisting in fitting first only Al2O3, CaO and TiO2 single oxide compounds separately with a unified description of the oxygen charge and O–O interaction term. For this purpose, a mean-square difference minimization of the partial pair-correlation functions with respect to the ab initio reference was performed. The potentials for the ternary oxide are finally built straightforwardly by adding purely Coulomb terms for dissimilar cation–cation interactions without further fit. This general and unified approach is transferable and successfully describes the structural and diffusion properties of the three single oxides as well as the ternary melts simultaneously. A possible underlying structural mechanism at the origin of the diffusion evolution with TiO2 content is proposed based on the formation of Ti induced triply bonded oxygen.

Analysis of the radiation parameters of pumice constituent compounds using XCOM

In this study, analysis of radiation parameters (linear attenuation coefficient, mean free path and half value layer) of pumice constituent compounds was carried out. Analyzes were done on the compounds of Al2O3, Fe2O3, SiO2, CaO, K2O and Na2O with a theoretical approach using the XCOM program for gamma photon energies 57Co (0.122 MeV; 0.1365 MeV), 133Ba (0.356 MeV), 54Mn (0.835 MeV), 137Cs (0.662 MeV), 60Co (1.173 MeV; 1.333 MeV), 65Zn (1.1155 MeV), 22Na (0.511 MeV; 1.275 MeV) and 40K (1.461 MeV). The results show that the Fe2O3 compound has the largest linear attenuation coefficient, while the largest for MFP and HVL is Na2O among other compounds.

Hydrocarbon generation from calcium stearate: Insights from closed-system pyrolysis

The total organic carbon of carbonate sediments includes a 5%–45% contribution from acid-soluble organic matter, particularly carboxylic acid salts. However, there is little information available on hydrocarbon generation from carboxylic acid salts. The objectives of this study were to investigate the extent and timing of hydrocarbon generation from calcium stearate. Thus, gold-tube nonhydrous pyrolysis experiments of calcium stearate were conducted from 250 to 600 °C at 50 MPa. Infrared spectroscopy and δ13C testing were also performed on solid pyrolysate and gaseous products, respectively, to trace changes of functional groups and stable carbon isotopes.Pyrolysis of calcium stearate produced hydrocarbons, CO2, CaO, CaCO3, coke, and other inorganic compounds of low molecular weight. A Van Krevelen diagram indicated that calcium stearate falls in the same region as hydrogen-rich type I kerogen. The maximum yield of methane generated from calcium stearate was as high as that from North Sea oil. Hydrocarbon generation from calcium stearate was related to cracking of the alkyl moiety and similar to that occurring in pyrolysis of n-C18. As a consequence of kinetic carbon isotope fractionation, with increasing temperature CO2 becomes enriched in 13C and CaCO3 becomes enriched in 12C. Notably, CaCO3 with very low δ13C values is probably an effective proxy indicating hydrocarbon generation from carboxylic acid salts, if no other CaCO3 is produced via thermochemical sulphate reduction processes. The optimized kinetic parameters demonstrate that calcium stearate had higher methane generation activation energies than those of n-C18 and type I kerogen. Hence, methane generation from calcium stearate is delayed when extrapolated to geological conditions. This retarded methane generation illustrates the vital role of carboxylic acid salts in the generation of deep oil and gas. Future research should concern the abundance of carboxylic acid salts in carbonate formations and the depositional environments that facilitate the formation of carboxylic acid salts.

ANALISIS KADAR KALSIUM OKSIDA (CaO) PADA BATU KARANG DI DAERAH PESISIR BAYANG DAMPELAS DONGGALA

Coral reefs are classified as coral or coral limestone. These corals contain of a high level of calcium purity with more than 90%. These clacium are in the from calcite (CaCO3). Calcite can be used in the industrial sector wich can be processed into a catalyst and use as a mixture 0f portland cement.its economic value increases by converting CaCO3 to CaO trough the calcination process at high temperatures. The coral sampels were taken from the coastal area of Bayang, Dampelas Donggala wich consisted of 2 samples. i.e coastal and montain coral reefs. The CaO levevls contained in coral reefs wer determined by qualitative and quantitative analysis method using XRF (X-Ray Fluorescence). XRF result showed that were CaO compounds in each coral reef sample. The CaO level in the coastal reef was 92,08% before calcination and 92,11% after calcination. Whereas the CaO level in te mountain coastal reef was 94,51% before calcination and 96,77% after calcination.

Experimental Determination of the Effect of CaO and Al2O3 in Slag Systems Related to the Conversion Process of High Copper Matte Grade

The slags generated in the conventional copper conversion process are mainly composed of Cu2O–Fe2O3–SiO2 with CaO, Al2O3, and MgO compounds—in concentrations up to 10 wt %. The present work contributes to the knowledge of the conversion process, generating experimental data for the phase diagrams of the Cu2O–Fe2O3–SiO2–Al2O3 and Cu2O–Fe2O3–SiO2–CaO systems. The experiments were carried out in a tubular furnace at temperatures of 1150 °C and 1200 °C, under a condition of saturation with tridymite and spinel. Once the equilibrium was reached, the samples were immediately quenched in water. The phases in the samples were observed through a scanning electron microscope (SEM) and the elemental composition of the phases were analyzed by means of energy-dispersive X-ray spectroscopy (EDS) detectors. The addition of Al2O3 and CaO into the Cu2O–Fe2O3–SiO2 system resulted in an appreciable displacement of the liquidus lines, corresponding to an expansion of the liquid in the tridymite primary phase field. The addition of CaO and Al2O3 combined was evaluated on industrial slags and from samples obtained in a Peirce–Smith furnace, with increasing amounts of CaO in the flux.