Experimental Study on Co-Pyrolysis Characteristics of Household Refuse and Two Industrial Solid Wastes

The calorific value of household refuse (HR) is greatly improved after classification, which includes the implementation of sufficient pyrolysis conditions. Therefore, a better pyrolysis effect can be achieved by co-pyrolysis with industrial solid waste (ISW) with high calorific value. In this work, HR and ISW were used as raw materials for co-pyrolysis experiments. The influence on the distribution of three-phase products after co-pyrolysis, the concentration of heavy metals and dioxins in the flue gas, and the distribution of PCDD/Fs isomers were studied. The results showed that, at a temperature of 600 °C and H/C = 1.3, of the formed material, the quantity of pyrolysis gas was approximately 27 wt.%, and the quantity of pyrolysis oil was approximately 40.75 wt.%, which mainly contained alkanes, olefins, and aromatic hydrocarbons. When S/C = 0.008, pyrolysis gas accounted for 25.95 wt.% of the formed material, and pyrolysis oil for 41.95 wt.% of the formed material. The ignition loss rate of pyrolysis coke was approximately 20%, and the maximal calorific value was 14,217 KJ/kg. According to the thermogravimetric experiment, the co-pyrolysis of HR and ISW can promote the positive reaction of pyrolysis, and the weight loss reached 62% at 550 °C. The emission of gaseous heavy metals was relatively stable, and the concentration of heavy metals slightly decreased. The main heavy metals in the ash were Cu, Fe, and Zn. The emission of dioxins could be effectively reduced by the pyrolysis of HR with ISW, and the produced dioxins were mainly synthesized from de novo synthesis. After pyrolysis, the toxic equivalent of dioxins in the flue gas was reduced from 0.69 to 0.29 ng I-TEQ/Nm3, and the distribution of dioxin isomers in the flue gas had little influence. The experimental results provide a theoretical basis for the application of co-pyrolysis technology with HR and ISW.

Characterization of Copper Tailings In Murgul Copper Plant (Artvin/Turkey) And Utilization Potential In Cement Mortar With Nano And Micro Silica

Due to the increasing demand for copper day by day, copper tailings (CT) are the wastes that mining and human-induced activities caused have become a problem all over the world due to the increasing demand for copper. This study evaluates the effect of using CT together with nano silica (NS) and micro silica (MS) in mortars as a partial substitution for cement on mechanical strength properties. Physical, morphological, chemical, mineralogical thermo gravimetric analyzes of CT have been made. In addition, heavy metal concentrations were determined. The mechanical features of the mortars produced by replacing by weight with different proportions of (5%, 10%, 15%) CT, 2% NS and 10% MS cement were determined. As a result, it has been observed that the sum of SiO2, Al2O3 and Fe2O3 of the CT, which has a mostly crystalline structure, is 91.40% and its ignition loss is 4.04%. An improvement in compressive strength (compared to the reference mixture) was observed with the use of 5% CT. Up to 10% of CT has provided standard compressive strength values in both NS and MS combinations.

Synthesis of Cryolite (Na3AlF6) from Secondary Aluminum Dross Generated in the Aluminum Recycling Process

Secondary aluminum dross (SAD) is regarded as a solid waste of aluminum recycling process that creates serious environmental and health concerns. However, SAD can also be used as a good source of aluminum, so that utilizing the SAD for the production of valuable products is a promising approach of recycling such waste. In the present work, a novel eco-friendly three-step process was proposed for the synthesis of cryolite (Na3AlF6) from the SAD, and it consisted of (1) water-washing pretreatment of SAD, (2) extraction of Al component via pyro-hydrometallurgy, including low-temperature alkaline smelting, water leaching and purification of leachate in sequence, (3) precipitation of cryolite from the purified NaAlO2 solution using the carbonation method. By analysis of the parameter optimization for each procedure, it was found that the maximum hydrolysis efficiency of aluminum nitride (AlN) in the SAD was around 68.3% accompanied with an extraction efficiency of Al reaching 91.5%. On this basis, the cryolite of high quality was synthesized under the following optimal carbonation conditions: reaction temperature of 75 °C, NaAlO2 concentration of 0.11 mol/L, F/(6Al) molar ratio of 1.10, and 99.99% CO2 gas pressure, and flow rate of 0.2 MPa and 0.5 L/min respectively. The formation of Na3AlF6 phase can be detected by XRD. The morphological feature observed by SEM revealed that the as-synthesized cryolite had a polyhedral shape (~1 μm size) with obvious agglomeration. The chemical composition and ignition loss of the as-synthesized cryolite complied well with the requirements of the Chinese national standard (GB/T 4291-2017).

Development and investigation on transmission efficiency of functionally graded material-based polybutylene terephthalate spur gears

Application of polymer composite gears is increasing due to their superior properties. They have lower inertia, less weight, and run much quieter than their metal counterparts. In the present work, functionally graded material-based glass fiber reinforced polybutylene terephthalate gears are fabricated with a novel horizontal centrifugal casting technique using an injection molding machine. Conventional technique is used to fabricate homogeneous polybutylene terephthalate gears. Polybutylene terephthalate reinforced with 15 and 30 wt% glass fibers is used to fabricate gears. Unfilled polybutylene terephthalate gear is also manufactured for comparative study. Gradation in functionally graded material gear is verified by scanning electron microscope analysis, and Shore D hardness is measured in three different locations of the fabricated functionally graded material gears. Gradation in functionally graded material gear is also verified by ignition loss test method. Continuous gradation is observed in functionally graded material gear by scanning electron microscope and confirmed by hardness test and ignition loss test. The objective of present work is to investigate and compare the transmission efficiency of homogeneous and functionally graded material gears during operation. A polymer gear test rig is used for the experimental work. Experiments are conducted at various torque and speed combinations for 0.2 million cycles. Life span of fabricated gear is also tested for 10 million cycles. The range of the torque is 0.8–2.6 N m and the range for rotational speed is 500–1400 r/min. The transmission efficiency of the fabricated gears is found to be sensitive to the operating torque.

Gasification system coupled to fixed bed column aiming adsorption of H2S from biomass

An overview of the characterization of biomass sugarcane bagasse, peanut shell and black grape peel for application of biofuels, based on laboratory tests. Initially a general explanation of the development of gasification for the production of synthetic natural gas from alternative sources, such as biomass, which can be converted from solid to gaseous fuel, passing through a process of purification through adsorption in a fixed bed system. The adsorbent was evaluated through BET, BJH, pH, humidity and ignition loss analyzes. The results of the combined gasification capacity of the adsorption column for the cleaning of the produced fuel gas and adsorption of the H2S were analyzed. The biomass results were discussed in terms of the energy potential as fuel based on the principal component analysis (PCA).

Total content of macroelements and trace elements in Holocene calcareous gyttja from the post-bog area of north-western Poland

The study covered 6 sites located in the Vistula glaciation area in north-western Poland, where the Holocene calcareous (gyttja) deposits occur. Three types of such calcareous deposits were isolated: marly (groundwater calcretes) (CaCO₃ > 80%, loss of ignition < 20%, non-carbonate fractions < 20%), calcareous gyttja (CaCO₃ 50–80%, loss of ignition < 40%, non-carbonate fractions < 40%), and clay calcareous gyttja (CaCO₃ 20–50%, loss of ignition < 30%, non-carbonate fractions < 60%). The content of major and trace elements was determined in different horizons. Several parameters of Holocene calcareous deposits were determined, namely carbonate status, total organic carbon, non-carbonate mineral fractions and several major and minor components. Close correlations between CaCO₃ and Ca, Mg contents, between non-carbonate fraction and K, Zn and Cu contents, as well as between ignition loss and Zn and Cu contents were observed in the sediments. The sediments exhibit vertical variability which relates to the genesis of sediments and soils. The highest content of macroelements was recorded in the uppermost layers for Ca, Mg, Na, and Mn and for microelements (trace elements) in bottom layers for S, P, K, Fe, Zn, Cu, Pb, and Ni.