Mechanism of anomalous manifestations δ13C CO2 underground water on Tashkent geodynamic range

The results of long-term isotope and gas measurements of various groundwater sources in the Tashkent artesian basin are presented. In addition to areal studies, the results of regime observations of selected wells at the Tashkent geodynamic test site are also presented to identify prognostic features as a precursor to strong earthquakes. The first results were obtained related to the manifestation of the Nazarbek earthquake on December 11, 1980, with a magnitude of 5.3, a source depth of 10 km. On the basis of this earthquake, the behavior of isotopic and gas precursors at the Ulugbek well, Tashkent geodynamic test site, was analyzed. A quantitative analysis was made of the anomalous manifestation of the gas and isotopic composition of groundwater in the Ulugbek borehole during the preparation and execution of the Nazarbek earthquake. Determination of CO2 release from rock samples recovered from deep wells of the landfill made it possible to quantify the ratio of “background” CO2 mixing from carbonate decomposition to anomalous. Judging by the obtained ratio, the rocks during the preparation of the earthquake should emit 2 times more carbon dioxide than the background CO2. This was confirmed by observations of the CO2 content in the well, when an increase in its relative concentration of 250% was recorded. The analysis of the δ13C time series, obtained as a result of long-term regime observations of the carbon isotopic composition of CO2 in the groundwater of the Tashkent geodynamic test site, made it possible to identify significant anomalies in the carbon content.

Conversion of Waste Cooking Oil to Biodiesel Catalysed by ZnAl Layered Double Hydroxide

In this study, the catalyst ZnAl layered double hydroxides (LDH) were successfully being synthesised with molar ratios 4:1 and 3:1 via free-alkali method by using ammonia solution instead of sodium hydroxide. The catalyst has been characterised before and after calcination by using XRD, TGA, SEM, BET and FT-IR. Based on the XRD result, the crystalline peak was successfully obtained and collapsed into mixed oxides of zinc oxide after the calcination. The carbonate decomposition was analysed by TGA to confirm the decomposition temperature of carbonate anions which is 250 °C. The surface area performed by BET showing an increasing from 213 m2/g to 224 m2/g on ZnAl LDH. Carbonate anions were confirmed by FT-IR result which are at 1390 cm-1 and 856 cm-1. 1 wt% of calcined ZnAl LDH catalyst has been used in the transesterification reaction using waste cooking oil (WCO). The compositions of biodiesel that has been detected using GC-FID are laurate, myristate, palmitate, linoleate, and stearate.

Thermodynamic Analysis of Siderite Ore Carbonate Decomposition Process at Roasting

Carbonate decomposition with significant heat energy absorption takes place at siderite ore oxidizing roasting in a shaft furnace. Thermal dissociation of complex carbonates comprising the siderite ore was studied. Thermodynamic analysis was carried out for a sideroplesite decomposition process. Formulas allowing determination of the carbonate dissociation and exchange energy rates were obtained using the regular ion solution theory. The ion composition and thermodynamic activity simulation results were described for sideroplesites as well as iron and magnesium cation shares. The work output is of certain interest as knowing the initial sideroplesite decomposition temperature and the carbonate dissociation rate the optimal dimensions of various zones throughout the shaft furnace height may be defined, the roasting process time may be calculated and the optimal heat treatment conditions as well as the firing rate may be established.

Fire Resistant Geopolymers Based on Several Clays Mixtures

This chapter aims to highlight the effect of clay mixture mineral composition and alkali concentration of potassium alkaline solutions on the thermal behavior of geopolymer materials. For this, three mixtures composed of kaolin (pure, impure kaolin or mixture of both), calcium carbonate, sand and potassium feldspar and three potassium alkaline silicate solutions with different concentrations were used (5, 6 and 7 mol.L−1). At first, the effect of rotary calcination parameters at 750°C such as the dwell time (30, 60, 120 and 180 min) and weight powder (100, 400 and 500 g) was investigated. It was demonstrated that the kaolin dehydroxylation is quasi complete (> 90%) and do not significantly depend on the dwell time and powder weight. Whereas the carbonate decomposition degree increases with the increase of dwell time and the decrease of powder weight but still not complete (<80%). These differences influence the feasibility of consolidated materials. Indeed, a flash setting occurs for samples based mixtures with high calcium carbonate decomposition degree (> 50%) and low wettability values (500 μL/g) for the three used alkaline solutions. The thermal behavior at 1000°C depends on the chemical composition of the aluminosilicate source and the concentration of alkaline solution. A conservation of the compressive strength at 43 MPa after thermal treatment at 1000°C of geopolymers based on mixture of pure and impure kaolin and a low potassium concentration solution (5 mol.L−1) was evidenced.

Determination of Key Parameters Required to Optimize Calcination Process in Ferrous Metallurgy Heating Plants

Lime is the product of calcination. Its formation is always related to removal of carbon dioxide generated in the course of carbonate decomposition. Ferrous metallurgy, construction material, chemical and food industry companies account for about 90 % of lime produced in the country. Ferrous metallurgy is the major consumer of commercial lime using up to 40 % of all produced lime. Currently, despite occurrence of new binding and artificially produced chemical compounds, lime remains the major chemical compound produced by the industry in terms of output. Various units (shaft, rotary tubular kilns and fluidized bed kilns) are used for calcination. Shaft kilns are used the most widely. Considering continuously growing demand for lime, the need occurs for intensification of the burning process and optimization of the shaft kiln operating conditions. This requires knowledge of calcination physicochemical and heat transfer process mechanisms. Thus, the work deals with the issues related to determination of the optimal specific fuel consumption for burning of limestone from a particular deposit. It may be done only basing on thermal calculations for an operating shaft kiln, what, in its turn, causes the need for determination of the whole set of limestone and lime heat transfer properties. The obtained work results may be used to optimize the operating conditions of not only shaft but also rotary kilns intended for limestone heat treatment.

Topological investigation of the reaction mechanism of glycerol carbonate decomposition by bond evolution theory

ELFs of glycerol carbonate and of its kinetic and thermodynamic decomposition product, 3-hydroxypropanal (+CO2).

Thermochemical Conversion of Biomass in the Presence of Molten Alkali-Metal Carbonates under Reducing Environments of N2 and CO2

The impact of N2 and CO2 atmospheres on the interaction between Eucalyptus pilularis biomass and a ternary molten carbonate eutectic (Li2CO3: Na2CO3: K2CO3) has been investigated at 600 °C and 900 °C. For lower temperature conversion under CO2, prevention of volatile release in the eutectic treated biomass is slightly higher than under N2 injection; however, similar bubble-shaped morphology of the remnant char is observed under both carrier gases. By increasing the temperature to 900 °C under CO2, the reverse Boudouard reaction begins to consume carbon fuel, while molten carbonate gasification also accelerates the reaction to a lower temperature set point (shifted from ~735 °C to ~640 °C). The mass loss of carbonate under CO2 and N2 at 900 °C is 0 (negligible) and 18 wt.%, respectively. In the absence of carbon particles, the decomposition of carbonate to M2O (l) and CO2 (g), as well as molten salt vaporization, are the sole potential routes of weight loss in an inert gas. Previous observations of biomass and eutectic mixture thermochemical conversion under N2 have suggested carbon/carbonate gasification is dominant at elevated temperatures, with production of CO expected. However, analysis of gas chromatography (GC) suggests that carbon/carbonate gasification is the weaker pathway by producing only 7 vol.% of CO, compared with molten carbonate decomposition with 27 vol.% CO2 emission for this system.