The Ni-GDC and Ni-SDC cermets with tailored microstructures are potential candidates for anode materials in intermediate temperature SOFCs. In this work, a modified citrate-nitrate combustion synthesis was employed for the preparation of cermets. It was demonstrated that the preparation technique ensured randomly distributed phases of NiO and GDC or SDC on a nanometre scale. Microstructure analysis revealed that during sintering under various conditions (from 1150 to 1400 °C), the NiO phase grew faster than the GDC or SDC phases; however, phases remained well within the sub-micrometre range. In order to describe the overall relative electrical conductivity of the cermets, the sine-wave approximation of conductivity change for porous materials was used. Higher relative densities of the cermets resulted in improved electrical conductivity. The most appropriate sintering temperature, which ensured relatively small grains and at the same time sufficiently high electrical conductivity, for both materials was determined to be 1200 °C.
Over the history of Aluminium production, the industries still search feasible and environmental viable solution to treat spent pot liner waste (SPL) as a by-product of the aluminium production process. SPL viable treatment is a global challenge for the primary aluminium industry, as is a mixed hazardous waste including first cut carbonaceous materials and second cut refractories. In the presented paper different possible solutions to this problem have been investigated. The latest techniques to treat SPL are presented with the highlight on chemical treatment technology. Laboratory tests confirmed that SPL treatment model cannot be feasible and viable within partial solutions. The systemic or broad solution can only fit a wide range of contemporary demands. Partly the cause is the allotrope form of the produced carbon cathodes and partly also the impurities in the waste material that disable effective one phase treatment. With the help of laboratory investigations, the possibilities of material utilization of SPL have been studied. The preliminary inquiry showed that interdisciplinary approach combines chemical procedures of SPL treatment based on the results of different preliminary tests can be successful.
Aluminum dust is a serious explosion hazard in the process industry. Therefore, any risk assessment requires knowledge of the data relating to the explosion hazard of the dust. We report on some experimental results that explain the influence of the particle size and the distribution, the specific surface area and the combustible components of various aluminum dusts on their sensitivity and the severity of an aluminum-dust explosion. Three samples of aluminum powder with different particle sizes were analyzed. The results reveal an extremely high maximum pressure rise for one of the samples, which can be assigned to a hybrid explosion caused by the presence of combustible additives in the dust. The results were compared with available literature data for similar dusts, which show that one of the analyzed powders has to be given a higher classification due to its larger Kst value, which also means a greater risk of explosion. The presence of a combustible additives in the dust reduces the sensitivity of the aluminum powder, but simultaneously substantially increases the severity of a dust explosion. It can be concluded that two of three investigated cases show a significant difference compared to the literature data, but for different reasons.
Biochar is a carbon-rich material produced with pyrolysis from natural ligno-cellulosic materials and must meet stringent quality criteria for use in the agro-ecosystem. The correct pyrolysis takes place at T in the range of 450 to 550 ° C, whereby the product must contain more than 50% C to be declared as biochar. At a lower temperature, more volatile components and less durability of carbon in the soil are obtained. With nutrient-enriched biofuels, we have a positive influence on the soil agro-ecosystem with increased porosity and sorption capacity of the soil, redox properties and neutralization capacity (liming effect), the ability to retain water and binding of nutrients in the soil, and long-term removal of carbon from the atmosphere (sequestration). Slovenia has the potential for the introduction of a circular economy and a value added chain, from preparation of lignocellulosic materials, which we have in abundance, through professionally guided pyrolysis, to the correct use of bio-char in agriculture to improve the soil.
We studied hybrid explosions, the influence of gas addition to dust dispersion, and the differences between dust and hybrid explosions. We have adapted the existing explosion chamber to allow hybrid explosions to be carried out. The paper will present the process of performing hybrid explosions, the results of explosion parameters and a comparison between the obtained results of dust and hybrid explosions of nicotinic acid and corn starch. The results were compared with literature data. pmax, (?p/?t)max and minimum explosion concentration were determined on the adjusted explosion chamber. Nicotinic acid and maize starch were determined by analysis of particle size and particle size distribution d50, dmodus and daverage. Based on the DTA analysis, we determined the thermal changes in the reaction and with the help of TG and DTG analysis we determined the moisture content in each sample. Based on the above parameters and methods, we confirmed the following hypotheses. The addition of a flammable gas other than air reduces the minimum explosion concentration for a given dust. By adding flammable gas to the powder dispersion, the dust concentration required to achieve maximum pressure and maximum pressure rise is reduced. The moisture content in corn starch reduces the turbulence and vigor of the reaction.