scholarly journals Effect of White Mud Addition on Desulfurization Rate of Molten Steel

2021 ◽  
Author(s):  
Tae Su Jeong ◽  
Min Kyo Oh ◽  
Yongsug Chung ◽  
Joo Hyun Park
Keyword(s):  
Sulfide Capacity ◽  
Steel Sample ◽  
Melting Rate ◽  
Partial Replacement ◽  
Desulfurization Rate ◽  
Ladle Slag ◽  
White Mud ◽  
Fluxing Agent ◽  
Positive Effect ◽  
Melting Experiment

AbstractFluorspar (CaF2) is commonly used to control the fluidity of slag in ladle-refining of steel. However, because it is desirable to reduce CaF2 consumption because of its environmental impacts, the industrial waste material such as white mud (WM) was investigated as a potential substitute for fluorspar. Steel sample (Fe-0.3C-0.9Mn-0.3Si-0.03Al-0.05S, mass pct) was melted in a high-frequency induction furnace, followed by additions of ladle slag (CaO-Al2O3-SiO2-5MgO-xCaF2, CaO/Al2O3=3, x = 0 to 10 mass pct) and fluxing agent (WM) at 1823 K (1550 °C). The desulfurization experiments were carried out by reducing CaF2 content in the ladle slag and increasing the addition of WM. Ladle slag with added WM showed an overall mass transfer coefficient of sulfur (kO) equivalent to or higher than that of conventional 10 mass pct CaF2-containing ladle slag. In a slag melting experiment based on DIN 51730 standard, the melting rate of mixed slag increased with the amount of WM added, which is considered to have a positive effect on the initial desulfurization rate. In addition, adding WM provided sulfide capacity of the slag equivalent to that of CaF2-containing slag. Consequently, the use of WM yielded slag having $$k_{{\text{O}}}$$ k O equivalent to or higher than that of conventional ladle slag with 10 pct CaF2, and thus, WM shows promise as a partial replacement for fluorspar.

scholarly journals Desulfurization Behavior of Incoloy® 825 Superalloy by CaO-Al2O3-MgO-TiO2 Slag

2021 ◽  
Author(s):  
Jin Hyung Cho ◽  
Johan Martinsson ◽  
Du Sichen ◽  
Joo Hyun Park
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Nuclear Power ◽  
High Performance ◽  
Internal Combustion Engines ◽  
Sulfide Capacity ◽  
Metal Phase ◽  
High Temperature Strength ◽  
Desulfurization Rate

AbstractNi-based superalloy, which has excellent high-temperature strength and corrosion resistance, is mainly used in aviation materials, high-performance internal combustion engines, and turbines for thermal and nuclear power generation. For this reason, refining the impurities in Ni-based superalloys is a very important technical task. Nevertheless, the original technology for the melting and refining of Ni-based superalloys is still insufficient. Therefore, in this study, the effect of the CaO-Al2O3-MgO-TiO2 slag on the removal efficiency of an impurity element sulfur in Incoloy® 825 superalloy, one of the representative Ni-based superalloys, was investigated. The desulfurization behavior according to the change of TiO2 content and CaO/Al2O3 (=C/A, basicity) ratio as experimental variables was observed at 1773 K (1500 °C). Although the TiO2 content in the slag increases to 15 mass pct, the mass transfer coefficient of sulfur in molten alloy showed a constant value. Alternatively, under the condition of C/A > 1.0 of slag, the mass transfer coefficient of sulfur showed a constant value, whereas under the condition of C/A < 1.0, the mass transfer coefficient of sulfur greatly decreased as CaO decreased. Hence, in the desulfurization of Incoloy® 825 superalloy using the CaO-Al2O3-MgO-TiO2 slag, the TiO2 content in the slag does not have a considerable effect on the desulfurization rate and desulfurization mechanism (metal phase mass transfer controlled regime), but the basicity of the slag has a significant effect on desulfurization mechanism. When the slag basicity decreases below the critical level, i.e., C/A < 1.0, which is corresponding to sulfur distribution ratio, Ls < 200, it was confirmed that the desulfurization mechanism shifts from the metal phase mass transfer-controlled regime to the slag phase mass transfer-controlled regime due to the variation in the physicochemical properties of the slag such as viscosity and sulfide capacity. In addition, the different desulfurization rates between steel and Ni alloy melts were discussed by employing the diffusivity of sulfur in both systems.

Effect of Alloying Elements on the Corrosion Behavior of Carbon Steel in CO2 Environments

CORROSION ◽  
10.5006/2705 ◽  
2018 ◽  
Vol 74 (5) ◽  
pp. 566-576 ◽  
Author(s):  
Yoon-Seok Choi ◽  
Srdjan Nešić ◽  
Hwan-Gyo Jung
Keyword(s):  
Carbon Steel ◽  
Corrosion Rate ◽  
Corrosion Behavior ◽  
Low Carbon Steel ◽  
Steel Sample ◽  
Alloying Elements ◽  
Low Carbon ◽  
Surface Analysis Techniques ◽  
Positive Effect ◽  
Effect Of Alloying

The objective of the present study was to evaluate the effect of alloying elements (Cr, Mo, and Cu) on the corrosion behavior of low carbon steel in CO2 environments. Six samples were prepared with varying Cr content from 0 wt% to 2 wt% and with added 0.5 wt% of Mo and Cu; the specimens had ferritic/pearlitic microstructures. Steel samples were exposed to a CO2-saturated 1 wt% NaCl solution with different combinations of pH and temperature (pH 4.0 at 25°C, pH 6.6 at 80°C, and pH 5.9 at 70°C). Changes in corrosion rate with time were determined by linear polarization resistance measurements. The surface morphology and the composition of the corrosion product layers were analyzed by surface analysis techniques (scanning electron microscopy and energy dispersive x-ray spectroscopy). Results showed that the presence of Cr and Cu showed a slight positive effect on the corrosion resistance at pH 4.0 and 25°C. At pH 6.6 and 80°C, regardless of the alloying elements, the trend of corrosion rate with time was similar, i.e., the corrosion rate of all specimens decreased with time resulting from the formation of protective FeCO3. A beneficial effect of Cr presence was clearly seen at “gray zone” conditions: pH 5.9 and 70°C, where steel sample without Cr showed no decrease in corrosion rate with time. The presence of Cr in the steel promoted the formation of protective FeCO3 with Cr enrichment and it decreased the corrosion rate.

scholarly journals Concrete manufactured with crushed asphalt as partial replacement of natural aggregates

2016 ◽  
Vol 66 (324) ◽  
pp. 101 ◽  
Author(s):  
L. Coppola ◽  
P. Kara ◽  
S. Lorenzi
Keyword(s):  
Compressive Strength ◽  
Cement Paste ◽  
Drying Shrinkage ◽  
Experimental Results ◽  
Recycled Aggregate ◽  
Partial Substitution ◽  
Partial Replacement ◽  
Negative Effect ◽  
Natural Aggregates ◽  
Positive Effect

The paper focuses on the reuse of crushed asphalt (GA) as a partial replacement (up to 20%) of natural aggregates for concrete manufacture. Addition of GA aggregates produced a positive effect on workability loss. The GA mixes, however, showed a significant tendency to bleed and segregate at the highest replacement percentage applied. GA led to a decrease of compressive strength in concrete (with respect to that of the reference concrete) up to 50% due to the weakness of the cement paste / recycled aggregate interface. To compensate for this negative effect, a reduction of w/c for the GA concretes was necessary. A decrease of w/c allowed the GA concretes to show drying shrinkage values substantially similar to those of reference concrete with the same cement factor. The experimental results confirmed the possibility of partial substitution (max. 15%) of natural aggregates with crushed asphalt for making concrete.

Eco-Friendly Basalt Fiber Reinforced Cement Composites (BFRC) Containing Waste Copper As Partial Replacement For Sand And Cement

2021 ◽  
Author(s):  
Mohammed Najı Ahmed Abu Aeshah ◽  
Gökhan Kaplan
Keyword(s):  
Basalt Fiber ◽  
Drying Shrinkage ◽  
Copper Slag ◽  
Sodium Sulphate ◽  
Partial Replacement ◽  
Taguchi Optimization ◽  
Freeze Thaw ◽  
Reinforced Cement ◽  
Strength And Durability ◽  
Positive Effect

Abstract In this study, the use of copper slag and aggregate together with basalt fiber in cement-based composites was studied. It was aimed to contribute to the ecosystem by using copper waste, which is an environmental problem, in cement-based composites. In addition, the effect of basalt fiber on the strength and durability properties of composites was investigated. Taguchi optimization was carried out for cement-based composites. In this context, Taguchi L18 matrix was used. Copper slag was used at rates of 0, 7.5% and 15%, and copper aggregate at rates of 0, 25% and 50%. Basalt fibers of 6 and 12 mm length were used at the rates of 1%, 2% and 3%. The w/b ratios of the mixtures were chosen as 0.40, 0.50 and 0.60. Durability tests such as permeability, freeze-thaw and sulphate resistance with fresh and hardened mortar properties were performed on 18 different mixtures. In terms of the 7, 28 and 91-day flexural and compressive strength of the mixtures, the use of 1% of 6 mm long fiber in the mixtures with a w/b ratio of 0.40 provided more positive results. In terms of freeze-thaw resistance, it is necessary to use 3% of 6 mm long fiber in mixtures with 0.40 w/b. The use of 7.5% copper slag reduced the water penetration depth. The use of 15% copper slag in mixtures affected by sodium sulphate reduced the expansion values. Since the increase in the ratio of copper aggregate decreased the aggregate volume, it caused the drying shrinkage values to increase. As a result, it was observed that copper slag has a more positive effect than copper aggregate for the strength and durability of composites. However, by using 25% of copper aggregate by sacrificing some features, it can contribute to the environment and ecosystem. The use of basalt fiber with a length of 6 mm and a ratio of 1% increased the mechanical properties, while the use of 3% contributed significantly to the freeze-thaw resistance. It was determined that copper wastes contribute to the environment and ecosystem by using them instead of cement and aggregate.

Effect of reduced pulp xylan content on wet end chemistry and paper properties — a pilot scale study

TAPPI Journal ◽  
2014 ◽  
Vol 13 (2) ◽  
pp. 29-37 ◽  
Author(s):  
KATJA LYYTIKÄINEN ◽  
ESA SAUKKONEN ◽  
MARKKU VÄISÄNEN ◽  
JUSSI TIMONEN ◽  
KAJ BACKFOLK
Keyword(s):  
Kraft Pulp ◽  
Scale Up ◽  
Pilot Scale ◽  
Partial Replacement ◽  
Paper Machine ◽  
Charge Balance ◽  
Paper Properties ◽  
Birch Kraft Pulp ◽  
Positive Effect ◽  
Xylan Content

In this scale-up study, we examined the effects of using varying amounts of fibers with reduced xylan content in paper. Bleached birch kraft pulp was partially or fully replaced by alkali-extracted pulp, and the effects of this replacement on the wet end chemistry of the paper machine and the resulting paper properties were determined. Our results show that paper properties can be maintained or improved when optimizing the partial replacement of bleached birch kraft pulp with alkali-extracted pulp. The incorporation of alkali-extracted pulp in paper machine stock had a positive effect on first pass retention and retention of chemicals. However, careful optimization of chemical dosages is required because of the altered charge balance in the wet end.

Experimental Study on Marble and Brick Powders as Partial Replacement of Cement in Self-compacting Mortar

2020 ◽  
Vol 13 (1) ◽  
pp. 45-57
Author(s):  
Dalila Boucherit ◽  
Farid Debiebt ◽  
Said Kenai ◽  
Maroua Amina Khalfaoui ◽  
Sara Chellali
Keyword(s):  
Experimental Study ◽  
Experimental Investigation ◽  
Partial Replacement ◽  
Environment Impact ◽  
Total Shrinkage ◽  
Brick Powder ◽  
Mechanical And Physical Properties ◽  
Marble Powder ◽  
Cutting Processes ◽  
Positive Effect

Aims: To produce a low environment impact concrete by recycling waste brick and waste marble. Background: Marble and brick wastes are produced as a byproduct during manufacturing or cutting processes. These materials could be used as a substitution to cement in mortar and concrete to reduce its environmental impact. Objective: To study the performance of self-compacting mortar with marbles and brick powders at the fresh and hardened states. Results: It is an experimental investigation where two Blaine finenesses of marble and brick powders were used. Rheological, mechanical and physical properties of the new composites were studied. Results: The results show that for optimal workability and compressive strength of SCM, the maximum percent of substitution must not exceed 5% for brick powder, whereas for marble powder it can reach up to 20% according to the fineness of powder. The incorporation of brick and marble powders separately decreases the shrinkage of SCM and the combination of both powders has a positive effect on its sorptivity coefficient and total shrinkage. Conclusion: Maximum 5% and 20% of brick and marble powder respectively are recommended for optimal properties of self-compacting mortar.

scholarly journals Statistical model used to assessment the sulphate resistance of mortars with fly ashes

2019 ◽  
Vol 9 (1) ◽  
pp. 536-544
Author(s):  
Julia Marczewska ◽  
Monika Jaworska
Keyword(s):  
Power Plants ◽  
Xrd Analysis ◽  
Sodium Sulphate ◽  
Cement Industry ◽  
Ternary Mixtures ◽  
Partial Replacement ◽  
Fly Ashes ◽  
Gibbs Triangle ◽  
Research Plan ◽  
Positive Effect

AbstractThe use of low (LCFA) and high (HCFA) calcium fly ashes in the cement industry allows the implementation of European Union proposals on waste management and energy saving. However, the possibility of using HCFA is limited, because the properties of such waste from coal-fired power plants must comply with national regulations. The paper shows the effect of partial replacement of Portland cement (OPC) by these fly ashes on the resistance of the sulphate attack of the mortars immersed in a 5% solution of sodium sulphate. In order to determine the optimal amount of ash additive, a research plan was designed using statistical methods using the Gibbs triangle for mixtures. Samples of control mortars of OPC, binary mixtures of HCFA or LCFA and ternary mixtures of HCFA/LCFA were made. The composition of the blends was designed in accordance with the statistical plan of the experiment for mixtures. The testing program included linear strains, compressive strength and microstructure tests using SEM with EDXA and XRD analysis. The results of laboratory tests and statistical analyzes have shown that fly ash has a positive effect on the sulphate resistance of cementitious composites.

POSSIBILITIES OF DETERMINATION OF OPTIMAL DOSAGE OF POWER PLANT FLY ASH FOR CONCRETE

2016 ◽  
Vol 78 (5-3) ◽  
Author(s):  
Rudolf Hela ◽  
Martin Tazky ◽  
Lenka Bodnarova
Keyword(s):  
High Temperature ◽  
Fly Ash ◽  
Partial Replacement ◽  
Optimal Dosage ◽  
Test Results ◽  
Temperature Combustion ◽  
High Production ◽  
Positive Effect ◽  
High Temperature Combustion

The paper describes possibilities of making use of high temperature combustion fly ash for production of concrete more effective. Efforts for maximal utilization of high temperature combustion fly ash are supported by high production of fly ash worldwide. Use of high temperature fly ash for concrete has to take into account considerably lower speed of hydration reactions compared to pure Portland cement. The paper states results of experimental determination of optimal dosage of fly ash as partial replacement of cement. Dosage of fly ash for production of concrete was optimized. Test results proved positive effect of dosage of fly ash with respect to granulometry of used cement and fly ash. Taking granulometry of fly ash and cement into consideration improves physico-mechanical properties of concrete compared to concrete with fly ash designed standardly without considering granulometry. 

scholarly journals Treatment and utilization of artificial aggregate in the production of cement composites

2021 ◽  
Vol 900 (1) ◽  
pp. 012032
Author(s):  
R Papesch ◽  
K Macalova ◽  
J Charvat ◽  
T Dvorsky ◽  
V Vaclavik
Keyword(s):  
Raw Materials ◽  
Steel Slag ◽  
Steel Production ◽  
Mineralogical Composition ◽  
Positive Influence ◽  
Partial Replacement ◽  
Steel Ladle ◽  
Cement Composites ◽  
Ladle Slag ◽  
Raw Materials Policy

Abstract The aim of the work is to find a suitable way of treatment of steel ladle slag for subsequent use as a partial replacement of the binder component in cement composites. The goal is based on the raw materials policy of the Czech Republic. Within this work is solved the issue of possible use of steel slag as the largest by-product of steel production. The work is focused on a specific ladle slag from ladle furnaces, by which are equipped the modern steel plants. Ladle slag is similar in chemical composition to Portland cement. However, its mineralogical composition should be taken into account in relation to its expansion reactions and lower hydraulic activity. One of the goals is the research of effect of particle size in cement-slag mixtures. The slag was ground for research on two different specific surfaces - coarsely in a vibrating mill and finely in a ball mill. The research within the experimental part of the work verified the positive influence of ladle slag on the properties of fresh and hardened mortar mixtures. Tensile bending strengths and compressive strengths are for some mixtures with ladle slag even higher than the strengths of the reference mixtures.

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