• Resources Recycling
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• v.31 no.6
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• pp.25-35
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• 2022

The adsorption/desorption behavior and separation conditions of vanadium and tungsten ions were investigated using a gel-type anion-exchange resin. In the adsorption experiment with the initial acidity of the solution, the adsorption rate of vanadium was remarkably low in strong acids and bases. Additionally, the adsorption rate of tungsten was low in a strong base. An increase in the reaction temperature increased the adsorption reaction rate and maximum adsorption. The effect of tungsten on the maximum adsorption was minimal. The adsorption isotherms of vanadium and tungsten on the ion-exchange resin were suitable for the Langmuir adsorption isotherms of both the ions. For tungsten, the adsorption isotherms of vanadium and tungsten were polyoxometalate. Both ion-exchange resins were simulated using similar quadratic reaction rate models. Vanadium was desorbed in the aqueous solutions of HCl or NaOH, the desorption characteristics of vanadium and tungsten depended on the desorption solution, and tungsten was desorbed in the aqueous solution of NaOH. It was possible to separate the two ions using the desorption process. The desorption reaction reached equilibrium within 30 min, and more than 90% recovery was possible.

• Resources Recycling
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• v.33 no.3
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• pp.38-47
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• 2024

Molybdenite is the primary molybdenum resource and is extracted via flotation due to its unique hydrophobic surface. Meanwhile, the grade and crystal size of mined molybdenite are decreasing. As a result, the size of the molybdenum ore required for liberation is decreasing, and the flotation process's feed size input is also decreasing. Therefore, in order to secure molybdenum, it is necessary to perform research on the flotation for the fine molybdenite. In this study, we developed a method to enhance the flotation efficiency of fine molybdenite particles in the range of 5-30 ㎛. The methodology involved implementing bubble size reduction and particle aggregation. Through simulations of bubble-particle collision probability and flotation experiments, we were able to find the ranges of bubble size and particle aggregate size that make fine particles float more effectively. This range provided the conditions for effective flotation of fine molybdenite particles. Therefore, we will implement the flotation conditions established in this study for fine molybdenum ore to improve the flotation process in molybdenum mineral processing plants in the future.

• Resources Recycling
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• v.17 no.2
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• pp.55-62
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• 2008

Amount of waste is always generated in industrialization process and it is gradually increasing. Domestic and industrial waste in 2003 increased by 9.5 percent than that of the last year(2002), whereas the amount of construction waste increased largely by 21 percent. Recently construction waste of total waste accounts for nearly 50 percent, waste concrete and Ascon from the construction waste takes up to 73 percent. Furthermore, amount of natural materials are gradually decreasing, that is, they are not sufficient any more. Owing to these reasons, the importance of recycling construction waste has been emphasized. The use of recycling aggregate makes the disposal of construction waste easier as well as protects environment from gathering raw aggregate. Also, it has the alternative effect economizing the insufficient new natural aggregate. This study employs the cost-benefit model to analyze the economic effect of construction waste recycling of Ascon which takes relatively high part of the total waste. The cost-comparison between raw aggregate and recycling aggregate were analyzed. With the model, the economic effect of Ascon recycling in 2003 and 2004 in capital area of Korea were analysed. Cost comparison between raw aggregate and recycling aggregate were also carried out. The result showed that the economic effect of Ascon recycling increased to 0.0808 for 2004 as compared 0.0694 for 2003. We could not conclude using above data, but this result shows that the economic benefit of Ascon recycling of construction waste has increased.

• Resources Recycling
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• v.31 no.5
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• pp.67-76
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• 2022

The furniture industry has a high possibility to create value-added and a high potential to create new occupations due to the characteristics of the industry, which mainly consists of small and medium-sized enterprises (SMEs). However, the used furniture, which has sufficient reuse value, is also crushed and used as solid refuse fuel (SRF) recently. Besides, the number of waste treatment companies continues to decrease, and it occurs congestion of wood waste. As a way to solve the issue, a business model development of remanufacturing used furniture can be suggested as an alternative due to its high circular economic efficiency. Remanufacturing business including furniture industry creates positive effects in various aspects such as economic, environmental and job creation. In other words, remanufacturing is an effective recycling way to reduce input resources and energy in the production process. The results of economic analysis show that the expected annual revenue from the single worker furniture remanufacturing site was 104 million won which is 3.11 times more than the average income of a single-worker household in Korea and its B/C ratio was estimated about 30 which means high business feasibility. Revenue through furniture remanufacturing also showed 320 times higher than that of SRF production from the perspective of weight. In addition, it is shown that the GHGs reduction from the furniture remanufacturing is 2.2 ton CO₂-eq. per year, which is similar to the amount of GHGs absorption effect of 937 pine trees or 622 Korean oak trees annually. Thus the results of this study demonstrate that it is important to adopt an appropriate recycling method considering the economic and environmental effects at the end-of-life stage.