【摘要】：金屬鎳冶煉過程中會排放以FeO.SiO2為主要成分的工業(yè)廢渣。全國累計堆存量超過4000萬噸,每年新增約200萬噸。鎳渣中Fe含量為40%~45%,SiO2含量為32%~36%,MgO為1%~11%,CaO為1%~3%,并含有不同數(shù)量的鎳、銅、鈷、金、銀等有價金屬,是潛力極大的可再利用二次資源,但因為其礦物組成復(fù)雜,至今未得到有效綜合利用,多以堆存的方式處理,不僅占用場地,且存在環(huán)境污染隱患,已經(jīng)成為急需取得突破的課題之一。本文針對金川鎳渣綜合利用中存在的問題,提出將鎳渣提鐵和脈石綜合利用相結(jié)合的技術(shù)思路,通過一次還原焙燒,同時得到直接還原鐵與膠凝材料兩種物質(zhì),實現(xiàn)鎳渣全組分綜合利用。還原焙燒實驗在可控溫度電阻爐中進(jìn)行,還原過程堿度通過添加石灰調(diào)整,還原劑為煤粉。實驗分別從還原劑加入量、還原時間、還原溫度、石灰加入量、反應(yīng)氣氛等方面進(jìn)行了研究。取得的研究成果如下:(1)熱力學(xué)軟件計算表明:硅酸二鈣在低溫下即可生成;850℃出現(xiàn)Ca3MgSi2O8,其穩(wěn)定存在區(qū)域較小,900℃時消失;在1100℃時,Al2O3和CaO反應(yīng)生成鋁酸三鈣;1350℃~1400℃時,游離氧化鈣大量減少并與硅酸二鈣結(jié)合成硅酸三鈣,鐵和硅酸三鈣可以同時存在。(2)連續(xù)升溫還原實驗當(dāng)物料粒度200目、還原劑配比15%、堿度為2.6、反應(yīng)溫度1480℃、反應(yīng)時間40min條件下鐵的還原率最高,可達(dá)62.9%。鐵單質(zhì)可通過濕法磁選分離,較佳磁選參數(shù)為粒度300目,磁場強度為先在3000Gs掃選,再進(jìn)行1000Gs精選,鐵回收率為78%。(3)連續(xù)升溫還原實驗可獲得直接還原鐵,但未得到膠凝組分C3S。分析其原因是在還原氣氛下,鎳渣中的Fe2+取代了部分Ca2+進(jìn)入C3S晶格中,當(dāng)熟料出爐冷卻時,Fe2+又重新被氧化成Fe3+,Fe3+不能取代C3S晶格中的Ca2+,離子的遷移導(dǎo)致C3S結(jié)構(gòu)不穩(wěn)定而分解。因而提出將實驗升溫過程分為兩段進(jìn)行。(4)“兩段法升溫”第一段升溫主要是還原FeO,反應(yīng)溫度定為800℃~1000℃,保溫一定時間使FeO充分還原為鐵單質(zhì),避免二價鐵離子對生成C3S的不利影響。第二段升溫溫度定在C3S的生成溫度區(qū)間1350℃~1500℃,以使物料充分反應(yīng)生成硅酸三鈣。實驗得到的較佳參數(shù)為:第一段升溫至1000℃,保溫時間為40min;第二段升溫至1480℃,保溫時間90min;物料急冷至室溫后可以同時得到鐵單質(zhì)與膠凝材料硅酸三鈣與硅酸二鈣。其中硅酸三鈣占總物料的55%,鐵的還原率為72%。通過不連續(xù)升溫還原焙燒后的物料快速冷卻后進(jìn)行磁選分離,鐵、鎳、銅等易還原組分以直接還原鐵合金形態(tài)存在可供電爐作原料,剩余組分轉(zhuǎn)化成具有膠凝性能的粉狀物料供礦山填充及水泥生產(chǎn)配料,實現(xiàn)了鎳渣組分的綜合利用,本課題研究成果可為相關(guān)行業(yè)提供參考依據(jù)。
[Abstract]:Industrial waste residue with FeO.SiO2 as the main component will be discharged during nickel smelting. The national accumulative reactor stock exceeds 40 million tons, adding about 2 million tons each year. The content of Fe in the nickel slag is 40% and the content of Sio 2 is 320.36%. The content of SiO2 is 320.The content of SiO2 is 32% and the amount of Cao is 1%, and the amount of valuable metals, such as nickel, copper, cobalt, gold, silver, and so on, is one of the most potential reusing resources. However, because of its complex mineral composition, it has not been used effectively, and it is mostly treated by stacking, which not only occupies the space, but also has the hidden trouble of environmental pollution, which has become one of the urgent problems that need to be broken through. Aiming at the problems existing in the comprehensive utilization of Jinchuan nickel slag, this paper puts forward the technical idea of combining the iron extraction from nickel slag with the comprehensive utilization of gangue, and obtains two kinds of materials, direct reduction iron and cementitious material, by single reduction roasting. The comprehensive utilization of nickel slag was realized. The reduction roasting experiment was carried out in a controlled temperature resistance furnace. The basicity of the reduction process was adjusted by adding lime, and the reducing agent was pulverized coal. The experiments were carried out from the aspects of reducing agent dosage, reduction time, reduction temperature, lime addition amount, reaction atmosphere and so on. The results obtained are as follows: (1) the thermodynamic software shows that dicalcium silicate can be formed at low temperature, the stable region of Ca3MgSi2O8, appears at 850 鈩，

本文編號：2402646