近幾年來，台灣產業能源使用低成本、高污染之化石能源比例偏高，使得CO2排放成長率高於國際水準，未來若面臨高額碳稅，勢必影響台灣產業發展與經濟成長。其中，鋼鐵工業的CO2排放量約佔全國總排放量之一成，其中又以傳統高爐製程為最。為追求綠色環境與產業永續發展，先進大型鋼鐵廠皆已投入低碳煉鐵技術之開發，來降低鋼材生產的CO2排放量。
本研究在針對稻殼炭、竹炭、椰殼炭與細焦炭進行物化性分析的基礎上，分別和燒石灰與鐵礦粉依不同比例混合，並使用高溫爐來進行碳熱還原(Carbothermic Reduction)，來調查預熱過程、生質炭種類以及不同成份組成對鐵礦還原反應的影響。
實驗結果發現，不同還原劑的鐵金屬化率與還原率依序為竹炭～椰殼炭>細焦炭>稻穀炭；使用稻殼炭為還原劑時，經碳熱反應過程所得之鐵碳複合團塊有明顯鐵珠分離的現象，鐵珠與直接還原鐵(Direct Reduced Iron, DRI)不同處在於殘碳高，係因經熔融過程，表面張力使之為球形；此外，鐵金屬化程度、還原率與渣鹽基度(Basicity, B2)有關，適當的B2可有效降低渣相熔點，有利還原反應的進行。
本研究以不同生質炭(Biomass Char)為還原劑還原鐵礦，模擬旋轉床爐(Rotary Hearth Furnace, RHF)製程所產製的碳熱還原產物不僅金屬化率可達70~96%，且殘碳介於2.48~3.9%之間，較現今鋼鐵廠中絕大多數皆被用來處理含鐵碳之固雜料70%還高，所產製的複合球團則以既存之鋼鐵冶煉製程來回收。此研究成果可供RHF製程條件、原料配比與改質劑添加設定之參考。

In recent years, Taiwan industry uses low cost, high pollution, high proportion of fossil fuel to make CO2 emission growth rate higher than the international standard. If Taiwan faces temporary high carbon tax, Taiwan industrial development and economic growth is bound to affected. Among the industries, the steel industry’s CO2 emissions account for 10% of total emissions, of which traditional blast furnace process the most. In order to pursuit green environment and industry sustainability, advanced large-scale steel mills have switched into developing low-carbon ironmaking technology to reduce CO2 emissions from steel production.
In this research, carbonaceous reductant like rice husk charcoal, bamboo charcoal, coconut shell charcoal (biomass char) and coke breeze's from different physical properties and chemical composition which influence the rate of intrinsic chemical composition and gas pore diffusion, respectively. Consequently, the overall reduction rates may also be affected. The iron oxides under investigation is commercial grade ores. The high temperature furnace experiments involve laboratory scale simulations of the carbothermic reduction. The goal of this study is to investigate the effects of preheating process and B2 to different biomass char on the metallization of iron-oxide-carbon composites.
The results showed that the iron metallization degree and reduction degree of various reducing agents is in the order of bamboo charcoal ~ coconut shell charcoal > coke > rice husk charcoal. When rice husk charcoal was used as reducing agent, iron bead proceeds has significantly separation phenomenon. The different between iron bead and general direct reduced iron (DRI) is high residual carbon content. Due to the melting process, the spherical is formed by surface tension. In addition, the degree of iron metallization and reduction degree are related to basicity (B2). Property B2 can benefit reduction reaction by lower slag melting temperature.
In this experiment, different biomass char was used as reducing agent of iron ore reduction reaction. Carbothermic reduction products produced by simulating rotary hearth furnace (RHF) process can achieved 70 ~ 96% of metallization, and the residual carbon content was between 2.48 ~ 3.9%. It is higher than residual materials, which is about 70% of metallization. It produced the iron-oxide-carbon composites could recover existing iron making and steel making process. The research results can provide reference in RHF process conditions, material mixture ratio and the addictives.

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