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1

Application of Arc Furnace Flue Ash in Casting Heat Insulation Riser

Zhu Junjie, Feng Jian, Liu Ling, Wang Huafang, Lu Jijun

Archives of Foundry Engineering

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2024

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Vol. 24, iss. 1

129--134

EN

Iron black commonly employs in thermal insulation riser sleeves due to its ability to react with aluminum powder, generating heat. However, the complex production process and unstable composition of iron black lead to high production costs. The potential of using arc furnace flue ash (AFFA) as a complete substitute for iron black and MnO2 and KNO3 oxidizing agents in conventional riser sleeves was investigated in this study. Waste material can be transformed into a valuable resource, while production costs can be reduced by utilizing arc furnace flue ash. The research examined the impact of varying types and amounts of arc furnace flue ash on riser sleeve temperature and holding time by conducting single-factor and orthogonal optimization experiments. The orthogonal optimization experiment determined that the optimum ratio of each oxidant was 6% arc flue ash, 3% MnO2 and 6% KNO3. At this time, the highest temperature was 1512℃ and the holding time was 244 s. Results indicated that different types of arc furnace flue ash used as an oxidizing agent demonstrated superior holding capacity and heat generation performance compared to iron black. Additionally, a comparative analysis of factory casting experiments using ductile iron 600-3 (IS) revealed that both arc furnace flue ash and iron black risers effectively countered shrinkage. However, arc furnace flue ash risers exhibited improved mechanical properties, as evidenced by the hardness of the castings.

2

Preparation and Performance Optimization of Organosilicon Slag Exothermic Insulating Riser

Lu Jijun, Qian Jiangbing, Yang Lei, Wang Huafang

Archives of Foundry Engineering

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2023

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Vol. 23, iss. 1

75--82

EN

The exothermic insulating riser played an important role in the solidification process of metal liquid for the improvement of casting quality. This paper focused on the use of organosilicon slag to replace part of the aluminum powder as an exothermic agent for the riser, to reduce production costs and turn waste into treasure. The experiments firstly studied the effect of organosilicon slag content on the combustion temperature and holding time and determined the components of the riser exothermic agent and organosilicon slag. On this basis, the effects of the content of Na3AlF6 flux and alkali phenolic resin binder on the combustion heating time and strength properties of the riser were studied. And the ratio of mixed oxidants was determined by single-factor orthogonal experiments to optimize the addition of three oxidants, Fe3O4, MnO2, and KNO3. Finally, the performance of the riser prepared after optimization was compared with that of the riser prepared with general aluminum powder. The results showed that with the mixture of 21% organosilicon slag and 14% aluminum powder as the exothermic agent, the highest combustion temperature of the prepared exothermic insulating riser was 1451℃ and the holding time was 193 s; the optimal content of Na3AlF6 flux was 4%, and the best addition alkali phenolic resin binder was 12%; the optimized mixing ratio of three oxidants was 12% for Fe3O4, 6% for MnO2, and 6% for KNO3. Under the optimized ratio, the maximum combustion temperature of the homemade riser was 52℃ and the heat preservation time was 14% longer compared with the conventional exothermic insulating riser with 25-35% aluminum powder.

3

Study on Reclamation of CO2-hardened Sodium Silicate Used Sands by CaO Powder

Lu Jijun, Yang Lei, Qian Jiangbing, He Wei, Wang Huafang

Archives of Foundry Engineering

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2022

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Vol. 22, iss. 3

99--106

EN

Aiming at the problems of wet reclamation consuming a lot of water, dry (mechanical) reclamation having wear and power consumption, this paper to find suitable reclamation reagents to reduce the influence of harmful substances in used sodium silicate sands. By comparing the reclamation effect of CaO, Ca(OH)2 and Ba(OH)2 reclamation powder reagents, it was concluded that CaO had the best reclamation effect. Through the single factor experiment, the influence of CaO on the reclamation effect was explored: 1. addition amount of CaO; 2. the additional amount of water; 3. reclamation time. The orthogonal results showed that the CaO reclamation effect was the best when the amount of CaO was 1.5%, the amount of sodium silicate was 4.0%, the amount of water added was 6.0%, and the reclamation time was 12.0h. In this experiment, 82.2% carbonate and 75.0 % silicate in used sands can be removed. The microscopic analysis of the reclamation sands was carried out by scanning electron microscope (SEM); The surface was relatively smooth, without large area cracks and powder accumulation. Compared with the used sands, the instant, 24h ultimate, and residual strengths of the reclaimed sands were increased by 536.5%, 458.1%, and 89.8%, respectively, which was beneficial to the reclamation of the CO2 sodium silicate used sands.

4

Effect of Methyl Silicone Oil to Moisture Resistance of Sodium Silicate Sands by Microwave Hardening

Wang Huafang, Gao Xiang, Yang Lei, He Wei, Lu Jijun

Archives of Foundry Engineering

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2022

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Vol. 22, iss. 1

43--47

EN

The sodium silicate sands hardened by microwave have the advantages of high strength, fast hardening speed and low residual strength with the lower addition of sodium silicate. However, the sodium ion in the sands will absorb moisture from the atmosphere, which would lead to lower storing strength, so the protection of a bonding bridge of sodium silicate between the sands is crucial. Methyl silicone oil is a cheap hydrophobic industrial raw material. The influence of the addition amount of methyl silicone oil modifier on compressive strength and moisture absorption of sodium silicate sands was studied in this work. The microscopic analysis of modified before and after sodium silicate sands has been carried on employing scanning electron microscopy(SEM) and energy spectrum analysis(EDS). The results showed that the strength of modified sodium silicate sands was significantly higher than that of unmodified sodium silicate sands, and the best addition of methyl silicone oil in the quantity of sodium silicate was 15%. It was also found that the bonding bridge of modified sodium silicate sands was the density and the adhesive film was smooth, and the methyl silicone oil was completely covered on the surface of the sodium silicate bonding bridge to protect it.

5

Automatic Measurement System of Hydrated Sodium Silicate Composition Analysis

Wang Huafang, Wang Quanrun, Zhang Wu, Gao Xiang, Lu Jijun

Archives of Foundry Engineering

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2021

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Vol. 21, iss. 2

5--8

EN

Sodium silicate is one of the most successful inorganic binder. Along with the broad application of sodium silicate for domestic and industrial purposes, the composition analysis, include modulus (m), ratio of SiO2:Na2O, Na2O%, SiO2%, and solid-containing content, is important for the products strength and service life. However, it is perplexing to operate, inefficient and low precision for traditional standard testing method of these parameters. In this study, an automatic measurement system of sodium silicate composition analysis, with the potential electrode for potentiometer titration, micro-controller, PCB, heater, stirrer, printer and micro peristaltic pump, was developed according to the determine method principle. The end-points of pH value in the two titrating steps, first was 4.3 and second was 6.0, were set in the micro-controller to control the reaction in the processing of the sodium silicate composition analysis. And all the potential signals of the pH electrode were transited in the special PCB for the micro-controller.