| 摘要: | 隨著國民生活水準提升，國人之不銹鋼消費量逐年增加，也產出大量不銹鋼集塵灰，面對全球環保要求以及政府大力推動循環經濟之浪潮，如何在符合節能減碳及經濟可行之原則下將不銹鋼集塵灰有效資源化，避免造成二次汙染是業者必須面臨的嚴峻挑戰。本研究重點乃採用高溫熔融還原法（Electric Smelting Reduction Furnace, ESRF），從不銹鋼製程產生的集塵灰中提煉有價值的鐵、鉻、鎳及鋅等金屬。不銹鋼集塵灰之組成以鐵、鉻、鎳及鋅四種元素最具資源化及經濟價值，佔總組成之30 ~ 68 %。不銹鋼廠集塵灰經混合後，與副原料混煉造粒製成壓球礦投入1550℃高溫熔融還原爐，利用焦碳等還原劑將集塵灰中之金屬氧化物還原以回收富含鐵、鉻及鎳的合金鐵及氧化鋅。本研究探討鹽基度對金屬回收率之影響，結果顯示鹽基度控制於1 ~ 1.09可得最佳之鐵、鎳及鉻回收率(90 %以上)，爐石之鎳、鉻毒性溶出濃度分別為0.16 及0.1 mg/L，將鹽基度控制於1.1 ~ 1.3之間，爐石之鎳及鉻溶出量最低，爐石可達最佳安定化效果。爐氣經製程袋式集塵器收集及分析，顯示二次灰氧化鋅含量約34 %，須將二次灰再次經壓球程序，投入高溫熔融還原爐中再次富集以符合產品規範。本研究固體總投入量為2175噸，總產出量為1158噸，減少部份為金屬氧化物於高溫熔融還原爐內，因高溫熔融產生氧化還原反應後，轉變為二氧化碳排入大氣。處理每噸不銹鋼集塵灰耗用電力3050 kWh，能源投入甚高，應加以改善。結果顯示高溫熔融還原法可有效回收不銹鋼集塵灰中有價金屬，並將非金屬物質經造渣程序產生安定化爐石，為同時可將不銹鋼集塵灰無害化、資源化及再利用之技術。;With the advancement of technology, more stringent regulation in environmental protection and the trend of implementing circular economy policies, how to recycle valuable metals from fly ash has become a big challenge. The aim of this study is to evaluate the effectiveness of electric smelting reduction furnace (ESRF) to recover valuable metals from the fly ash collected from stainless steel industry. Analysis of the compositions of stainless steel fly ash indicates that four elements including iron, chromium, nickel, and zinc, are of the most recovery value; and they account for 30-68% of the total compositions. The granulated pellet of ash is put into the electric smelting reduction furnace with a temperature of 1550℃ and reducing agent such as coke is applied to reduce the metallic oxide in the fly ash to recover iron, chromium, nickel, and zinc. Moreover, the impact of varying basicity on the recovery rate of of the targent metals is also evaluated and the results reveal that the best recovery rates of iron, chromium, and nickel can be obtained if the basicity is controlled at 1-1.09. The recovery rates of iron, chromium, and nickel reach≧90%. The results of toxicity characteristic leaching procedure (TCLP) reveal that leaching concentrations of nickel and chromium are 0.16 and 0.1 mg/L, respectively. The results also indicate that as the basicity is controlled between 1.1 and 1.3, the leaching concentrations of nickel and chromium are the lowest, demonstrating that operation under this condition results in the best stability of slag. Analysis of the ash collected by baghouse during manufacturing process reveals the zinc oxide content in the secondary ash is around 34%. The total solid input for the test run is 2175 tons with the total output of 1158 ton. The decrease in mass is caused by the oxidation and reduction of metallic oxide in ESRF, which turn into CO2 and is discharged into the atmosphere. The electricity consumed for treating one ton of stainless steel fly ash is 3050 kWh, indicating that the process is energy-intensive. How to reduce electricity consumption and reduce operating cost remains a big challenge. Overall the result reveals the electric smelting reduction furnace can effectively recycle valuable metals from stainless steel ash and this process can turn stainless steel fly ash into harmless, recyclable, and reusable products. |
