Papers by Keyword: Dross

Abstract: Dross formation during the melting of twitch aluminium scrap using boric acid washing method, was investigated employing a Taguchi-based approach. The study aimed to analyse the impact of different treatment durations with a 1M concentration of boric acid on dross formation characteristics. Experimental trials involved treating twitch aluminium scrap samples with boric acid solutions for 15 to 60 minutes. Subsequently, dross formation characteristics were analysed using statistical techniques based on Taguchi analysis. Results unveiled significant variations in dross formation among treatment durations, indicating that longer treatment times led to decreased dross formation, particularly notable beyond the 30-minute mark. Taguchi's analysis confirmed the significance of treatment duration on dross formation, underscoring the effectiveness of the boric acid washing method in reducing dross formation during twitch aluminium scrap melting. This study offers valuable insights into optimising the boric acid washing method to diminish dross formation during twitch aluminium scrap melting, thereby enhancing efficiency and quality in aluminium recycling processes. Notably, the aim of the research systematically investigate the influence of treatment duration with a 1M concentration of boric acid on dross formation characteristics, providing practical guidance for implementing the boric acid washing method in industrial settings. Keywords: Dross, twitch aluminium scrap, boric acid, Taguchi analysis, recycling, waste management.

Abstract: Additions of trace elements such as Phosphorus (P) and Germanium (Ge) are common practice to improve the oxidation resistance in Tin-Copper (Sn-Cu) wave solder systems, however, little insights are available regarding their combined role. In this article, the effect of trace P (<100ppm), in the presence of Ge (<100ppm), on the phase composition and microstructure of Sn-Cu-Ni wave solder dross is studied using various techniques including Synchrotron XRPD, SEM, FIB and TEM. We find that P additions, in the presence of Ge, result in the formations of SnO, SnO₂ and Ni₂SnP intermetallic in the dross whereas only SnO is present in the P-free equivalent. The crystal structure of Ni₂SnP is identified as orthorhombic with the space group Pnma. Based on the findings, it is evident that P not only influences the oxidation state of tin oxides but also reduces the concentration of effective Ni in the alloys via the formation of Ni₂SnP intermetallic.

Abstract: This research work aimed to apply the aluminium dross, waste of ADC12 and 6063 aluminium smelter grade as the raw materials produced plant fertilizer by acid treatment process with phosphoric and hydrochloric acid. Chemical properties have been tested as a chemical composition, pH, amount of macronutriants and heavy metals. The germination index testing was confirmed by using water extraction of the dross before and after pretreatment which effected on cantonese green lettuce seed. The results showed that more than 50% by weight of dross composition was alumina mainly. Others components were included oxides of silicon, magnesium, sodium, potassium, calcium, iron, and zinc. Interestingly, there are not appeared of harmful heavy metal elements. For fertilization properties, mainly nutrients as nitrogen (N), phosphorus (P), and potassium (K) were investigated. Also, the germination test was investigated in an organic fertilizer standard test method as germination index (GI). Normally, the result was found that GI of un-treated dross was lower than that of a control sample. The treated dross with HCl and phosphoric acid presented higher GI than that of a reference sample. It was concluded that both grades of dross can be used as a fertilizer with acid treatment.

Abstract: Phosphorus (P) is often added to wave-solder baths as an anti-oxidation agent for older generation eutectic Sn-37wt%Pb solders. For Pb-free solder alloys trace amounts of germanium (Ge) have been added successfully in Sn-0.7wt%Cu-0.05wt%Ni for anti-oxidation purposes during the wave soldering process. Despite this practice, there is little information on how P and Ge distribute in solder alloys and dross in this alloy system. In this paper, the effects of combinations of trace levels of Ge (< 100ppm) and P (< 100ppm) in Sn-Cu-Ni solder alloys and their dross has been investigated by XRD and SEM/EDS. It was found that the weight fraction of tin oxides in the dross is increased with an addition of less than 100ppm P. The dross consists on SnO oxide with Sn in samples containing Ge and no P, while SnO and SnO₂ oxide are both present when P and Ge additions are made. In samples containing P, (Cu,Ni)₆Sn₅ and Ni-P and/or Ni-Sn-P intermetallics particles were found.

Abstract: s In this study, Computational Fluid Dynamics (CFD) was used to simulate the flow and temperature distribution in zinc pot of hot-dip galvanizing process. The flow and temperature distribution in a base-case zinc pot was compared to that in other two optimized zinc pots, one of which had a dam between ingot and snout and another one had a reduced heating power. The simulation shows that the dam impedes the flow of low temperature liquid zinc around zinc ingot to strip and increases the fluctuation of zinc level. By reducing the heating power, however, the fluctuation of zinc level could be suppressed.

Abstract: Aluminium dross is composed of metallic aluminium and non-metallic compounds such as oxides, nitrides and carbides. The dross created during primary and secondary aluminium production can amount up to 1% of the total tonnage and may contain up to 90% aluminium metal. The conventional procedure for dross treatment is to use salt for separating the metallic aluminium and the non-metallic compounds. The resulting salt cake has to be processed further. This paper describes a process using a plasma rotary furnace with a non-oxidizing atmosphere and heated by a graphite plasma torch to separate the aluminium from the non-metallic compounds. A pilot scale furnace (charge 500kg) has been designed and tested. In the experiment presented here a mixture of aluminium and aluminium dross were charged into the furnace. Good atmosphere control was maintained during the experiment. No wear on the refractory and only minor wear on the graphite electrodes was observed after the experiment. The result shows that 98.9% of the aluminium in the charged raw materials was recovered in tapped metal without using any salt anywhere in the process. The aluminium metal tapped from the process had only minor increase in the trace elements compared to the metal originally produced. The inclusion content in the metal was also not increased significantly. The residual non-metallic compounds should be possible to recycle in the electrolysis or used in the cement industry.

Abstract: Hot dip galvanizing is being widely used to the numerous constructional steels such as a guard rail of high way, various types of structural steel for manufacturing ship and for some other fields etc.. Recently, the cost of zinc is getting higher and higher, thus, a proper manufacturing process should be developed possibly to reduce the cost of production. one of hot dip galvanizing process, that is, flux solution immersion process is very important to control more effective coating. However, flux solution is deteriorated with increasing its using time because dissolved iron from structural steel due to continuous flux treatment was increasingly increased, which is resulted in coating badness and increment of dross. In this study, the effect of additives to elimination of iron dissolved in flux solution was investigated with four types of inner solution, that is, solution of inner barrel was filled with seawater, NaOH, thiourea, including parameters of amounts of NH₄Cl(5,10,15 and 20g) and electrolysis experiment was carried out with applied current density at 20mA/cm². For the best elimination effect of iron from flux solution, it is considered that inner barrel with separator should be filled with inner solution different from original flux solution which is involved in iron ion, and the inner solution should be composed with seawater added with additives such as NH₄Cl(10g), NaOH(0.2 g) and thiourea(0.5g) when the applied current density by electrolysis method is 20mA/cm².

Abstract: Hot dip galvanizing is being widely used to the numerous constructional steels such as a guard rail of high way, various types of structural steel for manufacturing ship and for some other fields etc.. Recently, the cost of zinc is getting higher and higher, thus, a proper manufacturing process should be developed possibly to reduce the cost of production. one of hot dip galvanizing process, that is, flux solution immersion process is very important to control more effective coating. However, flux solution is deteriorated with increasing its using time because dissolved iron from structural steel due to continuous flux treatment was increasingly increased, which is resulted in coating badness and increment of dross. In this study, the effect of additives to elimination of iron dissolved in flux solution was investigated with four types of inner solution, that is, solution of inner barrel was filled with seawater, NaOH, NH4Cl, including parameters of amounts of thiourea(0.2,0.4 ,0.6 and 0.8g) and electrolysis experiment was carried out with applied current density at 20mA/cm2. The best effect for elimination of iron from flux solution is considered that inner barrel with separator should be filled with solution different from original flux solution which contained in iron ion, that is, its inner solution should be composed with seawater added with additives such as thiourea(0.4g), NaOH(0.2 g) and NH4Cl(10g). In particular, we can see that the optimum amount of thiourea to extract effectively iron from flux solution is 0.4g.

Abstract: This paper proposes a novel manufacturing process of a fine mesh filter screen with a pulsed laser. The fine mesh filter screen, made of stainless steel, has many small diameter holes with high aspect ratio and fine pitch. In the conventional process, an electron beam drills in a vacuum. However, this is very costly because of the expensive equipment required and batch process. Therefore, a laser drilling process for small diameter hole drilling in air with higher flexibility was proposed. The post-processes after the laser drilling completed the fine mesh filter screen.

Abstract: Hot dip galvanizing is being widely used to the numerous constructional steels such as a guard rail of high way, various types of structural steel for manufacturing ship and for some other fields etc.. Recently, the cost of zinc is getting higher and higher, thus, a proper manufacturing process should be developed possibly to reduce the cost of production. one of hot dip galvanizing process, that is, flux solution immersion process is very important to control more effective coating. However, flux solution is deteriorated with increasing its using time because dissolved iron from structural steel due to continuous flux treatment was increasingly increased, which is resulted in coating badness and increment of dross. In this study, elimination of iron dissolved in flux solution was investigated with some types of inner solution which is added with additives such as seawater, NH4OH, NaOH, NH4Cl and thiourea, and electrolysis experiment was carried out with parameters of applied current density. For elimination of iron from flux solution, it is considered that inner barrel with separator should be filled with solution different from original flux solution which is involved in iron ion, that is, the inner solution which is made up seawater added with additives such as NH4Cl (5g), NaOH(0.5g) and thiourea(0.5g) is the most desirable solution to effectively extract iron from flux solution. An optimum applied current density for the most extraction effect of iron through electrolysis experiment is thought to be 20mA/cm2 .