Optimization Of Calcination Conditions Research Articles

High-temperature dolomite decomposition: An integrated experimental and computational fluid dynamics analysis for calcium looping and industrial applications

The thermal decomposition of dolomite was investigated as a potential low-cost and high-performance precursor to CaO in the calcium looping process, which shows great promise when integrated with carbon capture and storage and thermochemical energy storage technologies. Experimental thermogravimetric analysis (TGA) and computational fluid dynamics (CFD) modelling were used to study the isothermal calcination process of dolomite considering industrially relevant conditions, focusing on high temperatures (800–1200 °C), sample sizes (12–18 mm), different calcination atmospheres (air and CO2) and gas velocities (0.2–3 m·s−1). Based on experimental findings, optimal calcination conditions for industrial applications require a minimum temperature of 1000 °C to achieve complete conversion within 25 min and smaller particles for faster conversion rates. Calcination atmosphere is flexible as CO2 concentration shows minimal impact on conversion rates. Laminar flow gas velocity is not a limiting factor and its value should be considered based on other aspects (i.e., costs). Higher particle initial porosity is seen to increase reactivity and thermal efficiency. The CFD model was validated with experimental data, resulting in determination coefficients (R2) higher than 0.9 for all simulated cases. Model predictions revealed insights into particle level phenomena during calcination, such as increased rates at higher temperatures with proportional self-cooling effects, wake formation enhancing fluid mixing and the presence of a thermal boundary layer reducing heat transfer. The findings presented in this paper can be used in future work to determine reaction mechanisms and optimize kinetic parameters for decomposition, as well as further optimize other aspects of the process at industrially relevant operating conditions.

Adsorption Mechanism and Regeneration Performance of Calcined Zeolites for Hydrogen Sulfide and Its Application.

Hydrogen sulfide (H2S) is a very toxic, acidic, and odorous gas. In this study, a calcined zeolite was used to investigate the adsorption performance of H2S. Among particle size, calcination temperature and time calcination temperature and time had significant effects on the adsorption capacity of H2S on the zeolite. The optimal calcination conditions for the zeolite were 332 °C, 1.8 h, and 10-20 mm size, and the maximum adsorption capacity of H2S was approximately 6219 mg kg-1. Calcination could broaden the channels, remove the adsorbed gases and impurities on the surface of zeolites, and increase the average pore size and point of zero net charge. As the zeolite adsorbed to saturation, it could be regenerated at the temperatures between 200 and 350 °C for 0.5 h. Compared with the natural zeolite, the adsorption capacities of dimethyl disulfide, dimethyl sulfide, toluene, CH3SH, CS2, CO2, and H2S were significantly higher on the calcined zeolite, while the adsorption capacity of CH4 was lower on the calcined zeolite. A gas treatment system by a temperature swing adsorption-regeneration process on honeycomb rotors with calcined zeolites was proposed. These findings are helpful for developing techniques for removing gas pollutants such as volatile sulfur compounds and volatile organic compounds to purify biogas and to limited toxic concentrations in the working environment.

Pre-treatment through reductive calcination for CO2 mineralization and selective battery metal extraction from laterites

The world needs an increasing supply of nickel and cobalt production as battery materials for sustainable development. However, the complexity of laterite deposits and the need to control CO2 emissions challenge the enhanced global supply from laterites. This work investigates the effects of calcination as a pre-treatment for selective battery metal extraction from both limonite laterite and saprolite laterite together with concurrent achievement of CO2 mineralization. Calcination under a reducing atmosphere of CO-N2 or CO-CO2 gas mixtures can significantly enhance the extraction of critical metals from both limonite and saprolite laterites. With calcination, the hydrated silicate minerals and ferric oxides converted to reactive olivine and ferrous oxide. The calcines thus can participate in the CO2 mineralization process to stabilize CO2 as mineral carbonates and release nickel and cobalt arising from the CO2 mineral carbonation into solution as complex ions with a ligand (such as sodium nitrilotriacetate, NTA). The optimum calcination conditions are 20 ∼ 30 % CO in CO-CO2 gas mixture at 700 °C. Beyond the optimum range results in the inadequate conversion of ferric to ferrous at too low CO concentration or over calcination of ferric to metallic iron at too high CO concentration. At the optimum conditions, the nickel & cobalt extraction and CO2 mineralization can reach 90 %, 93 %, and 39 % from laterite. Each tonne saprolite with the pre-treatment of calcination can recover 20.5 kg nickel, 0.59 kg cobalt, and simultaneously sequester 142 kg CO2 as stable mineral carbonates. The pre-treatment through slightly reductive calcination enables the robust suitability of the developed process for all layers of laterites for both critical battery metal recovery and carbon mineralization.

Tailoring self-pulverized low-calcium clinker for CO2 sequestration

To reduce energy consumption and greenhouse gas emissions in the cement industry, this study develops a novel low-calcium clinker with self-pulverization properties. The clinker is synthesized from limestone and sandstone raw materials and comprises dicalcium silicate (2CaO·SiO2 (C2S)) as the primary mineral and rankinite (3CaO·2SiO2 (C3S2)) as the auxiliary mineral. The influence of calcination temperature, cooling rate, and holding time on clinker pulverization and mineral formation is investigated through a series of experiments. The optimal calcination condition involves heating at 1240 °C for 1 h, followed by natural cooling, resulting in a self-pulverized low-calcium clinker (SPLCC) with main mineral is γ-C2S and contains β-C2S, C3S2, and C2AS (Calcium alumina feldspar (2CaO·Al2O3·SiO2)). The self-pulverized clinker exhibits a pulverization ratio of 93.0 %, a specific surface area of 666.4 m2/kg, and an average particle size of 8.2 μm. Additionally, the clinker displays excellent carbonation reactivity, with the compressive strength reaching 69.3 MPa and 82.2 MPa after 4 h and 24 h of CO2 curing, respectively. The carbonation products are identified as calcite and silica gel. SPLCC can reduce and sequester approximately 277.3 kg of CO2 emissions compared to the hydration of Portland cement clinker when considering the preparation and curing stages. The results highlight the potential of SPLCC as a sustainable cementitious material.

Modeling and optimization of biodiesel from high free‐fatty‐acid chicken fat by non‐catalytic esterification and mussel‐shell‐catalyzed transesterification

AbstractBACKGROUNDIn this study, biodiesel was prepared from chicken fat via a transesterification reaction using Mussel shells as a catalyst. Pretreatment of chicken fat was carried out using non‐catalytic esterification to reduce the free fatty acid content from 36.28 to 0.96 mg KOH/g oil using an ethanol/ fat mole ratio equal to 115:1. In the transesterification reaction, the studied variables were methanol: oil mole ratio in the range of (6:1 ‐ 30:1), catalyst loading in the range of (9‐15) wt%, reaction temperature (55‐75 °C), and reaction time (1‐7) h. The heterogeneous alkaline catalyst was greenly synthesized from waste mussel shells throughout a calcination process at different calcination times of (1‐5) h and temperatures of (700‐900) °C. The catalyst was characterized using BET, SEM, EDX, XRD, and FTIR.RESULTSIn the transesterification reaction, the best values of the studied parameters were: 21:1 methanol: oil molar ratio, 12 wt% catalyst loading, 5 h reaction time, and 63°C reaction temperature, which gave 96.2% methyl esters content. For catalyst synthesis, it was found that the optimum calcination conditions were 900 °C and 3 h, which resulted in a specific surface area of 10.5 m2/g and a large pore volume of 0.0033 cm3/g.CONCLUSIONA calcium oxide catalyst was successfully prepared from mussel shells. This catalyst was used to transesterify the chicken fat into biodiesel. The prepared catalyst exhibited a high active surface area and a pore volume, confirming that the CaO catalyst produced from waste mussel shells worked effectively, steadily, and affordably to produce renewable biodiesel. The best working conditions for the transesterification reaction were determined using the central Composite Design method (CCD). © 2023 Society of Chemical Industry.

Rare earth ions doped Bi2MoO6 luminescent materials: Pechini sol-gel synthesis, down-conversion and up-conversion multicolor emissions, and potential applications

A series of rare earth ions (Eu3+, Sm3+, Yb3+/Er3+, Yb3+/Ho3+, Yb3+/Tm3+) doped bismuth molybdate (Bi2MoO6) phosphors with excellent multicolor luminescence have been synthesized by a facile Pechini sol-gel method. XRD, EDX, and XPS results confirm the highly crystalline orthorhombic phase of Bi2MoO6 and verify that the rare earth ions (RE3+) are effectively integrated into the Bi2MoO6 matrix. During the synthesis process, the calcination conditions play an important role in obtaining the luminescent host matrix, and the optimal calcination condition for the Bi2MoO6 products is determined of 800 °C for 2 h. The Eu3+ and Sm3+ doped Bi2MoO6 samples display intense red and orange-red light under UV/visible excitation whereas the Yb3+/Ln3+ (Ln = Er, Ho, and Tm) doped Bi2MoO6 materials emit green, green, and blue colors when excited by NIR light. Both down-conversion (DC) and up-conversion (UC) multicolor luminescence are obtained by doping the proper Ln3+ activators into the Bi2MoO6 host. The doping concentrations of various RE3+ ions are optimized to generate advantageous phosphors and the luminescence mechanisms of RE3+ ions are systematically studied. The LED devices fabricated by Bi2MoO6:Yb3+/Ln3+ UC phosphors exhibit dazzling multicolor emissions under an injection current, which directly discloses that the as-prepared materials may be of great potential in LEDs and optoelectronic devices. Interestingly, the Bi2MoO6:Yb3+/Er3+/Eu3+ phosphors can simultaneously exhibit red and yellow-green DC emissions and green UC light under excitation of 464, 488, and 980 nm. The multi-mode emission features illustrate that the as-synthesized phosphors may have application prospects in anti-counterfeiting applications.

Mechanical performance and environmental potential of concrete with engineering sediment waste for sustainable built environment

The extensive use of underground space has led to an increasing amount of engineering sediment waste, which occupies about 60% of construction waste in China. At present, most of the engineering sediment waste is randomly dumped, occupying a lot of land resources and hindering sustainability of built environment. To solve these problems, this work proposes the recycling of engineering sediment waste via calcination and subsequent use as a cement substitute in concrete for construction. The optimal calcination condition is evaluated through strength activity index method. The mechanical properties, environmental and economic benefit of the concrete prepared with various substitution rates of calcined engineering sediment waste are determined using mechanical tests and the life cycle assessment. A multi-criteria analysis method is employed to comprehensively estimate the performance of concrete in terms of compressive and flexural strengths, global warming potential, energy consumption, and economic cost. The effect of calcined engineering sediment on the pozzolanic activity, cement hydration, CH content and microstructure of concrete has been quantitatively evaluated to reveal the mechanism behind the variation of mechanical properties. The concrete with 50% substitution of calcined engineering sediment showed superior environmental performance and economic benefit than those of reference concrete. This work contributes to an effective method for converting sediment waste into valuable resources to prepare concrete with low environmental impact and good mechanical performance, thereby promoting resource conservation and contributing to sustainability of built environment.

Investigation of Process Parameters of Phosphogypsum for Preparing Calcium Sulfoaluminate Cement

Preparing calcium sulfoaluminate cement (CAS) from solid waste phosphogypsum (PG) instead of natural gypsum is an effective way to utilize solid waste. In this paper, CAS clinker was successfully prepared from PG and the mineral content of calcium sulfoaluminate (C4A3S¯) in the sample was above 65%. The effects of raw material ratio, calcination temperature, and time on clinker composition were investigated. The mechanical properties of different samples were tested. The optimum ratio for preparing CAS using PG was 42.23% limestone, 17.43% PG, and 40.34% bauxite. The optimal calcination conditions are a high temperature of 1250 °C for 45 min. The 3-day compressive strengths of the laboratory-prepared CAS were all above 50 MPa. It was found that as the calcination temperature increased, the amount of C4A3S¯ produced gradually increased. Temperatures above 1300 °C resulted in the decomposition of C4A3S¯. The calcination time did not significantly affect the mineral composition of the clinker or the strength of the cement. C4A3S¯ was observed to be rounded and hexagonal platelets with crystal sizes of 1 to 2 μm, a relatively small size that is favorable to the hydration of C4A3S¯, as observed by SEM images. In addition, the high calcination temperature affected the particle morphology of C4A3S¯, changing it from a well-defined polygonal structure to a molten state. The test results provide helpful information for improving PG utilization and applying PG in CAS production.

Preparation and decarburization characteristics of SiO2-Al2O3 composite aerogel modified by potassium carbonate

In this paper, the preparation of potassium carbonate modified SiO2-Al2O3 composite aerogel, the carbonation characteristics of K2CO3 and the decarburization characteristics of regeneration cycle were studied. The influence of loading rate on CO2 adsorption was studied by using a fixed bed reactor, and the microstructure of the samples was analyzed by combining SEM and BET. The results show that during the alkali fusion sintering of Na2CO3, the Si-O-Si and Si-O-Al bonds break, the crystal structure is destroyed, and the covalent bond of mullite is transformed into the ionic bond of nepheline. Through orthogonal test, taking the specific surface area of aerogel as the measurement index, the optimal calcination conditions are determined as follows: 900 ℃, reaction for 60 min, Na2CO3 addition ratio of 0.5. The more K2CO3 is loaded, the less the corresponding active sites on the surface of the carrier. When the loading is 30%, the maximum CO2 adsorption capacity is 2.86 mmol·g–1. Excess K2CO3 will plug the pore structure, destroy the diffusion of CO2, and reduce the diffusion and utilization efficiency. The percentage of mesoporous pore volume decreased from 94.21% to 89.32%, indicating that the active component K2CO3 was mainly filled in the mesoporous. After 10 cycle regeneration tests, the CO2 adsorption capacity of the adsorbent decreased by 10.49%. The pore structure of the adsorbent was stable and the decarburization performance was excellent.

Nanostructured magnetite-ceria-based composite: Synthesis, calcination, properties, and applications

Magnetite and magnetite/ceria composites prepared by chemical procedures in various mutual ratios were exposed to calcination treatment in a temperature interval between 473 K and 1073 K. A combination of several experimental methods has provided detailed structural, phase, and magnetic properties utilisable for selection of optimal compositions and calcination conditions from the viewpoint of degradation ability tested using parathion methyl and paraoxon. It was shown that the ceria content, selected between 5 wt% and 50 wt%, influences magnetic properties. Its optimal amount was determined to be above 20 wt% and the calcination temperature of 773 K when the highest rate constant, slightly above 0.06 min−1, was obtained for parathion methyl in acetonitrile using a degradation test.

Preparation and 3D printing building application of sulfoaluminate cementitious material using industrial solid waste

The iron and steel industry , the power industry, and the mining industry each produce large volumes of industrial solid waste. These industrial solid waste are dumped in huge volumes over a wide geographical distribution , causing far-reaching environmental harm in China. To date, the preparation of eco-friendly construction materials from industrial solid waste is one of the feasible large-scale utilization methods. This paper studied the preparation of different types of environmentally benign novel green sulfoaluminate cementitious materials with different contents of Ca 4 Al 6 SO 16 and Ca 2 SiO 4 by using stone tailing, coal gangue , secondary aluminum slag, and desulfurization gypsum . Moreover, the prepared solid-waste-based sulfoaluminate cementitious material (SCM) was used to further prepare 3D printing material. The results show that the optimal calcination conditions are 1260–1290 °C for about 1 h, and the main mineral phases in the clinker system are Ca 4 Al 6 SO 16 , Ca 2 SiO 4 , and Ca 4 Al 2 Fe 2 O 10 . The compressive strengths of hydrated specimens reached 40, 61, and 86 MPa after curing for 1d, 3d, 28 d, respectively, and the main mineral phases of the hydration product were ettringite , alumina gel, and silica gel . After improving its properties by using a suitable accelerant and retardant , the SCM showed advantages of a controlled setting time in the range of 15–80 min, rapid hardening, and rapid attainment of mechanical strength. The compressive strength of hydrated specimens reached 15–20 MPa after curing for 2 h, and the modified SCM proved to be eminently suitable for 3D printing applications. These results provided not only a sustainable mode for 3D printing construction materials and development, but also an innovative strategy for full utilization of industrial solid waste. • A new synthetic method to prepare eco-friendly 3D printing building materials is described. • The novel technological process of SCM from hazardous and industrial solid wastes was proposed. • Effect of raw mix composition and sintering temperature on properties of SCM was analyzed.

Performance of cement-based materials containing calcined coal gangue with different calcination regimes

The storage of coal gangue (CG) takes up a lot of lands and pollutes the environment. Calcined CG has the potential to be used as supplementary cementitious material. In this paper, the CG from Yibin, Sichuan province of China were treated with different calcined temperature, holding times and cooling modes, and the microtopography, phase composition and pozzolanic reactivity of calcined CG were studied. Meanwhile, the fluidity, mechanical properties, hydration products, and pore structure of cement paste and mortar with different calcined CG were analyzed. The apparent color of coal gangue under different treatment methods has also been studied to promote its better application for a wider range in cement-based materials. Results showed that there exists an optimal calcination condition of calcined CG at 800 °C and holding time of 2 h. Rapid cooling and slow cooling reduced the activity of calcined CG. Calcined CG powder would reduce the fluidity of cement mortar. However, proper calcination temperature and sufficient holding time could eliminate it to some extent. It was also found that calcination temperature has a greater impact on the early age reactivity of CG when compared to different temperature treated CG powder, C8T2 sample has the best early activity. Compared to rapid cooling, slow cooling and water-cooling mode, room temperature cooling would result in higher reactive CG. CG powder after proper thermal treatment could refine the pore structure of the hardened cement paste in the later age (28 days), reduce the harmful pores content (>100 nm), and increase harmless pores content (<100 nm) in hardened cement paste. It was found that the CG powder of calcined at 800 °C for 2 h, cooling in water and room temperature might be more suitable as the supplementary cementing material combined the apparent color, pozzolanic reactivity, and preparation process.

Fabrication of B4C ultrafiltration membranes on SiC supports

The fabrication of B4C ultrafiltration membranes is described. Firstly, a semi-dilute B4C slurry was environmentally-friendly prepared by aqueous colloidal processing, optimizing its dispersion by sonication, and used to deposit B4C membranes onto SiC macro-porous supports by dip-coating. Secondly, the resulting green membranes were characterised microstructurally by scanning electron microscopy (SEM), and pressureless sintered within the intermediate sintering regime. Thirdly, the sintered membranes were calcined in air to clean them from possible free carbon in the smallest pores, with the optimal calcination conditions having been identified by thermogravimetry coupled with mass spectrometry. Next, the calcined, sintered membranes were characterised microstructurally by SEM, tested mechanically against scratching, and characterised texturally by capillary flow porometry, thus identifying the optimal among them. Lastly, as a complement to the fabrication study, the filtration permeability of the optimal membrane was evaluated using deionized water. This work thus paves the way towards the fabrication of ceramic membranes based on B4C, lighter and potentially more durable than others, for filtration applications.

Pozzolanic reactivity of aluminum-rich sewage sludge ash: Influence of calcination process and effect of calcination products on cement hydration

The application of aluminum-based flocculant in wastewater treatment results in a large amount of aluminum-rich sewage sludge. This work investigated the influence of calcination process on physicochemical characteristics and pozzolanic activity of aluminum (Al)-rich sludge ash and studied the effect of sludge ash on cement hydration. The results showed that higher calcination temperature from 600 ℃ to 900 ℃ increased the amorphous content in sludge ash. The pozzolanic activity of sludge ash calcined at 800 ℃ and 900 ℃ was confirmed by Frattini test. In view of strength activity index of blended mortar and energy conservation, the optimal calcination condition of sewage sludge ash was calcined at 800 ℃ with air-cooling. The addition of sludge ash promoted the transformation of ettringite to monosulfate phase in cement paste. However, the high Al concentration dissolved from S6 and S7 ash inhibited significantly the cement hydration and resulted in low compressive strength values of the blended mortars. The pozzolanic reaction of S8 and S9 ash produced more hydration heat and additional Al-bearing products such as katoite and monosulfate which contributed to the strength development of mortars. Furthermore, the heavy metals in sewage sludge can be immobilized in ash structure during calcination process and the structure of hydration products, which ensures the environmental security of sludge ash utilization in construction materials.

Optimum Calcination Condition of Waste Stabilized Adobe for Alkali Activated High Volume Adobe-Slag Binder Cured at Room Temperature

This study aims to determine the most convenient calcination temperature and calcination duration of waste-stabilized Adobe (AB) to produce a new alkali-activated binder. Waste-stabilized Adobe mainly consists of soil, CaCO3 as a stabilizer, and straw (for strengthening). The availability of raw materials for making Adobe presents the waste-stabilized Adobe as a potential product for a new alkali-activated binder. Waste-stabilized Adobe collected from an abandoned damaged building in the village of Inonu in Northern Cyprus, ground and calcined at the following temperatures: 450, 550, 650, 750, 850, and 950°C. The calcination at each temperature was held for different durations 1, 3, 5, and 7 h. Raw and calcined waste stabilized Adobe structures were investigated using XRF, TGA-DTA, XRD, FTIR, and SEM. Considering technical and environmental views related to energy consumption, waste stabilized Adobe calcined at 750°C for 1 h presented the most promising results regarding the production of a new precursor for alkali-activated binder. This study also presents the effect of ground granulated blast furnace slag (GGBFS) usage on the fresh and hardened properties of optimum calcined AB-based alkali-activated pastes cured at room temperature. GGBFS was used to partially replace AB to form a binary composite raw material system and seven experimental groups were designed according to replacement levels of 0%, 5%, 10%, 15%, 20%, 25% and 30% (by mass). Alkali-activated high volume waste-stabilized Adobe-slag pastes prepared using Na2SiO3-to-NaOH ratio of 2 and 12 M concentration of Sodium Hydroxide. The fresh property as flowability and the hardened property as the compressive strength of the alkali-activated pastes with different GGBFS contents were investigated. The results indicated that the incorporation of GGBFS increased the flowability of fresh alkali-activated pastes. A 28-day compressive strength of 43.75 MPa can be obtained by a 30% replacement level of GGBFS.

Controlled synthesis and photoluminescence behaviors of Lu2O2SO4:Eu3+ and Lu2O2S:Eu3+ phosphors

A “general” amorphous precursor that can synthesize Eu3+ doped Lu2O2SO4 and Lu2O2S phosphors was prepared from commercially available Lu2O3 (AR), HNO3 (99.95% purity), (NH4)2SO4 (AR) and NH3·H2O (99.95% purity) as raw materials via a facile co-precipitation method. Based on this, block-like Lu2O2SO4:Eu3+ phosphors were synthesized by calcination in air, and mixed structures of near-spherical and rod-like Lu2O2S:Eu3+ phosphors were synthesized by calcination in a confined sulfuration atmosphere created using a solid-state method. Studies have shown that the molar ratio of SO42−:Lu3+ and the aqueous ammonia titration volume is very important in the co-precipitation process, the optimal ratio was selected as 25:1, and the optimal 1.5 M NH3·H2O solution volume was selected as 22 mL in this study. In the subsequent calcination process, the effect of calcination temperature on the target product was studied. The optimal calcination conditions are a calcination temperature of 800 °C for 2 h in air and 500 °C for 2 h in a closed sulfuration atmosphere, respectively, for the oxysulfate and oxysulfide phosphors. The photoluminescence (PL) behavior of the two phosphors was systematically investigated. The oxysulfate and oxysulfide phosphors show the characteristic red-light emission of the Eu3+ ion at about 620 and 628 nm, respectively, which originates from the 5D0-7FJ (J = 0,1,2,4) transition of the Eu3+ ion. The luminescence quenching types of both phosphors were dominated by exchange interactions and the optimum Eu3+ molar concentrations were found to be 3.0% for Lu2O2SO4:Eu3+ and 6.0% for Lu2O2S:Eu3+. The oxysulfide phosphor had a PL intensity ∼2.15 times stronger than the oxysulfate phosphor. The CIE color coordinates of the Lu2O2SO4:Eu3+ and Lu2O2S:Eu3+ phosphors are (0.6551, 0.3444) and (0.5842, 0.413), which belong to the categories of reddish-orange and orange colors, respectively. A shorter fluorescence lifetime (∼12.650 μs) and CCT (1738 K) was observed for the oxysulfide phosphor relative to those of the oxysulfate phosphor (∼377.956 μs and 2787 K).

Effect of Calcination Conditions on MnOx/Al2O3 Catalytic Efficiency for NO Oxidation

AbstractCalcination conditions in the catalyst preparation process have a significant influence on catalyst performance. To explore the optimal calcination condition of MnOx/Al2O3 catalysts for NO ...

Thermally Treated Waste Silt as Filler in Geopolymer Cement.

This study aims to investigate the feasibility of including silt, a by-product of limestone aggregate production, as a filler in geopolymer cement. Two separate phases were planned: The first phase aimed to determine the optimum calcination conditions of the waste silt obtained from Società Azionaria Prodotti Asfaltico Bituminosi Affini (S.A.P.A.B.A. s.r.l.). A Design of Experiment (DOE) was produced, and raw silt was calcined accordingly. Geopolymer cement mixtures were made with sodium or potassium alkali solutions and were tested for compressive strength and leaching. Higher calcination temperatures showed better compressive strength, regardless of liquid type. By considering the compressive strength, leaching, and X-ray diffraction (XRD) analysis, the optimum calcination temperature and time was selected as 750 °C for 2 h. The second phase focused on determining the optimum amount of silt (%) that could be used in a geopolymer cement mixture. The results suggested that the addition of about 55% of silt (total solid weight) as filler can improve the compressive strength of geopolymers made with Na or K liquid activators. Based on the leaching test, the cumulative concentrations of the released trace elements from the geopolymer specimens into the leachant were lower than the thresholds for European standards.

Particular pollutants, physical properties, and environmental performance of porous ceramsite materials containing oil-based drilling cuttings residues.

The mineral compositions of oil-based drilling cutting residues (ODCRs) were similar to that of clay, which could be used as raw materials for ceramsite. In this study, the maximum addition of ODCRs and the optimum calcination conditions were studied by single factor experiment. The microstructure, phase composition, and element distribution of ceramsite were studied by means of SEM, XRD and EDS. The ceramsite, with a 40% ODCRs content, was calcined at 1000 °C for 2 h. After cooling down, the ceramsite had good physical properties, including low density, low water absorption, and high compressive strength. The bulk density was 850-970 kg/m3, the water absorption was 2.1-10%, and the cylinder compressive strength was 6-11.8 MPa. And most of the heavy metals in ODCRs were effectively solidified. The organic toxic substances were completely burned. The leaching amount of harmful elements met the requirements of Chinese standards. The ceramsite would avoid secondary pollution to the environment. So the ceramsite made from ODCRs can not only improve the processing speed of ODCRs, but also be used as building materials, greening materials, industrial filter materials, etc., and increase its environmental and social benefits.

Optimization of Calcination Conditions for Cu/ZnO/Al2O3-ZrO2 Catalyst

Promoted Cu/ZnO catalyst was synthesized on Al2O3-ZrO2 support. Effects of calcination conditions on the catalytic performance in a CO2 hydrogenation reaction were studied systematically using the response surface methodology (RSM). The application of RSM with rotatable central composite design (RCCD) for optimization on the influence of catalyst’s calcination variables on the CO2 conversion and methanol selectivity is presented. The calcination variables studied include temperature, A (181–518 °C), ramping rate, B (1–30 °C/min), and duration, C (1–7 h). From the RSM-generated model, the optimum calcination condition for this catalyst was 350 °C with 17.5 °C/min ramping rate for a 4 h duration. At the optimum calcination condition, the catalyst exhibited a Brunauer–Emmett–Teller (BET) surface area of 147 m2/g, a pore volume of 0.31 cm3/g, and a pore diameter of 8.1 nm.