錳鐵:錳和鐵組成的鐵合金。主要分類:高碳錳鐵(含碳為7%)、中碳錳鐵(含碳1.0~1.5%)、低碳錳鐵(含碳0.5%)、金屬錳、鏡鐵、硅錳合金。
在煉(lian)(lian)鋼中,用(yong)(yong)(yong)(yong)作脫(tuo)氧劑和合(he)金(jin)添加劑,是用(yong)(yong)(yong)(yong)量多的鐵(tie)合(he)金(jin)。冶(ye)(ye)煉(lian)(lian)錳鐵(tie)用(yong)(yong)(yong)(yong)的錳礦一(yi)般要求含(han)(han)錳40~50%,錳鐵(tie)比(bi)(bi)大于7,磷錳比(bi)(bi)小于0.003。冶(ye)(ye)煉(lian)(lian)前,碳酸錳礦要先經焙燒(shao),粉礦需經燒(shao)結造(zao)塊。含(han)(han)鐵(tie)含(han)(han)磷高(gao)的礦石(shi)(shi)一(yi)般只(zhi)能搭配(pei)使用(yong)(yong)(yong)(yong),或通過選擇(ze)性還原(yuan)(yuan)煉(lian)(lian)得低(di)(di)鐵(tie)低(di)(di)磷的富錳渣。冶(ye)(ye)煉(lian)(lian)時用(yong)(yong)(yong)(yong)焦炭作還原(yuan)(yuan)劑,某些廠也配(pei)用(yong)(yong)(yong)(yong)無煙煤。輔(fu)原(yuan)(yuan)料主(zhu)要為石(shi)(shi)灰,冶(ye)(ye)煉(lian)(lian)錳硅(gui)合(he)金(jin)時一(yi)般要配(pei)加硅(gui)石(shi)(shi)。
碳素(su)錳(meng)(meng)(meng)鐵(tie)(tie)一般標準為(wei)(wei)(wei)含錳(meng)(meng)(meng)75~80%,中(zhong)(zhong)國(guo)為(wei)(wei)(wei)適(shi)應錳(meng)(meng)(meng)礦品(pin)位(wei)低(di)的原料條件(jian),規定了含錳(meng)(meng)(meng)較低(di)的牌號(電爐錳(meng)(meng)(meng)鐵(tie)(tie)含錳(meng)(meng)(meng)65%以(yi)上(shang)(shang),高爐錳(meng)(meng)(meng)鐵(tie)(tie)含錳(meng)(meng)(meng)50%以(yi)上(shang)(shang))。冶煉碳素(su)錳(meng)(meng)(meng)鐵(tie)(tie)過(guo)去主要用(yong)(yong)高爐,隨著(zhu)電力工業的發展,用(yong)(yong)電爐的逐(zhu)漸增(zeng)多。目前西歐和中(zhong)(zhong)國(guo)用(yong)(yong)高爐為(wei)(wei)(wei)主,挪威、日本用(yong)(yong)電爐,蘇聯、澳大(da)利亞、巴西等(deng)國(guo)新建錳(meng)(meng)(meng)鐵(tie)(tie)工廠也采用(yong)(yong)電爐。
高爐(lu)冶煉
一般采(cai)用1000米(mi)3以下的(de)高(gao)(gao)(gao)(gao)爐,設(she)備和(he)生產工藝大體(ti)與煉(lian)鐵高(gao)(gao)(gao)(gao)爐相(xiang)同。錳(meng)礦石在(zai)由爐頂(ding)下降(jiang)的(de)過程中(zhong),高(gao)(gao)(gao)(gao)價的(de)氧化錳(meng)(MnO2,Mn2O3,Mn3O4)隨溫(wen)(wen)(wen)度(du)(du)升高(gao)(gao)(gao)(gao),被(bei)CO逐步還原(yuan)到MnO。但MnO只(zhi)能(neng)在(zai)高(gao)(gao)(gao)(gao)溫(wen)(wen)(wen)下通過碳直接還原(yuan)成(cheng)金屬,所以冶煉(lian)錳(meng)鐵需(xu)要較高(gao)(gao)(gao)(gao)的(de)爐缸(gang)溫(wen)(wen)(wen)度(du)(du),為此煉(lian)錳(meng)鐵的(de)高(gao)(gao)(gao)(gao)爐采(cai)用較高(gao)(gao)(gao)(gao)的(de)焦(jiao)比(bi) (1600公斤/噸左右)和(he)風(feng)溫(wen)(wen)(wen)(1000℃以上(shang))。為錳(meng)損耗變(bian)低,爐渣應(ying)保持較高(gao)(gao)(gao)(gao)的(de)堿度(du)(du)(CaO/SiO2大于(yu)1.3)。由于(yu)焦(jiao)比(bi)高(gao)(gao)(gao)(gao)和(he)間接還原(yuan)率(lv)低,煉(lian)錳(meng)鐵高(gao)(gao)(gao)(gao)爐的(de)煤氣產率(lv)和(he)含CO量(liang)(liang)比(bi)煉(lian)鐵高(gao)(gao)(gao)(gao)爐為高(gao)(gao)(gao)(gao),爐頂(ding)溫(wen)(wen)(wen)度(du)(du)也較高(gao)(gao)(gao)(gao) (350℃以上(shang))。富氧鼓風(feng)可使(shi)爐缸(gang)溫(wen)(wen)(wen)度(du)(du)變(bian)高(gao)(gao)(gao)(gao),使(shi)焦(jiao)比(bi)變(bian)低,增加(jia)產量(liang)(liang),且因煤氣量(liang)(liang)減少可降(jiang)爐頂(ding)溫(wen)(wen)(wen)度(du)(du),對錳(meng)鐵的(de)冶煉(lian)有(you)很好的(de)改進作用。
電爐冶煉
錳(meng)鐵(tie)(tie)(tie)的(de)(de)還原冶(ye)煉(lian)有熔劑(ji)法(fa)(fa)(又稱低(di)(di)(di)錳(meng)渣(zha)(zha)法(fa)(fa))和無(wu)熔劑(ji)法(fa)(fa)(高錳(meng)渣(zha)(zha)法(fa)(fa))兩種(zhong)。熔劑(ji)法(fa)(fa)原理與(yu)高爐冶(ye)煉(lian)相同(tong),只是以(yi)(yi)電能代替加(jia)熱(re)用的(de)(de)焦炭。通(tong)過配(pei)加(jia)石(shi)灰形成(cheng)高堿度爐渣(zha)(zha)(CaO/SiO2為1.3~1.6)以(yi)(yi)減少錳(meng)的(de)(de)損失。無(wu)熔劑(ji)法(fa)(fa)冶(ye)煉(lian)不加(jia)石(shi)灰,形成(cheng)堿度較(jiao)低(di)(di)(di)(CaO/SiO2小于 1.0)、含錳(meng)較(jiao)高的(de)(de)低(di)(di)(di)鐵(tie)(tie)(tie)低(di)(di)(di)磷富錳(meng)渣(zha)(zha)。此法(fa)(fa)渣(zha)(zha)量(liang)少,可(ke)使電耗變低(di)(di)(di),且因渣(zha)(zha)溫較(jiao)低(di)(di)(di)可(ke)使錳(meng)的(de)(de)蒸發損失變低(di)(di)(di),同(tong)時(shi)副(fu)產(chan)品富錳(meng)渣(zha)(zha)(含錳(meng)25~40%)可(ke)作冶(ye)煉(lian)錳(meng)硅合(he)金的(de)(de)原料,取得較(jiao)高的(de)(de)錳(meng)的(de)(de)綜合(he)回收率(lv)(90%以(yi)(yi)上(shang))。現在工業生產(chan)大多采用無(wu)熔劑(ji)法(fa)(fa)冶(ye)煉(lian)碳(tan)素錳(meng)鐵(tie)(tie)(tie),并(bing)與(yu)錳(meng)硅合(he)金和中、低(di)(di)(di)碳(tan)錳(meng)鐵(tie)(tie)(tie)的(de)(de)冶(ye)煉(lian)組成(cheng)聯合(he)生產(chan)流程。
現代大(da)型錳鐵還原電爐容(rong)量達40000~75000千伏安,一般為(wei)(wei)固(gu)定封閉式。熔(rong)劑法的(de)冶煉電耗一般為(wei)(wei)2500~3500千瓦?時(shi)/噸,無熔(rong)劑法的(de)電耗為(wei)(wei)2000~3000千瓦?時(shi)/噸。
錳(meng)硅(gui)(gui)合金用(yong)封(feng)閉或(huo)半封(feng)閉還原(yuan)電爐冶煉(lian)。一(yi)般采用(yong)含(han)二氧化硅(gui)(gui)高、含(han)磷(lin)低的錳(meng)礦或(huo)另外配加(jia)硅(gui)(gui)石為原(yuan)料(liao)(liao)。富錳(meng)渣(zha)含(han)磷(lin)低、含(han)二氧化硅(gui)(gui)高是冶煉(lian)錳(meng)硅(gui)(gui)合金的好原(yuan)料(liao)(liao)。冶煉(lian)電耗一(yi)般約3500~5000千(qian)瓦(wa)?時/噸。入爐原(yuan)料(liao)(liao)先作預(yu)處理,包括(kuo)整粒(li)、預(yu)熱、預(yu)還原(yuan)和粉料(liao)(liao)燒結等,對電爐操作和技術經濟指標起很好的作用(yong)。
電(dian)爐(lu)精煉 中、低碳錳(meng)鐵一般(ban)用(yong)1500~6000千(qian)伏安電(dian)爐(lu)進(jin)行(xing)脫硅精煉,以(yi)錳(meng)硅、富錳(meng)礦和(he)石灰為(wei)原料(liao),其反應為(wei):
MnSi+2MnO+2CaO─→3Mn+2CaO?SiO2
采(cai)用(yong)高堿(jian)(jian)度渣(zha)(zha)可(ke)使爐渣(zha)(zha)含(han)錳(meng)(meng)變(bian)低(di),減(jian)少由棄渣(zha)(zha)造成的(de)錳(meng)(meng)損失。聯合生產(chan)中采(cai)用(yong)較低(di)的(de)渣(zha)(zha)堿(jian)(jian)度(CaO/SiO2小于1.3)操(cao)作,所得含(han)錳(meng)(meng)較高(20~30%)的(de)渣(zha)(zha)用(yong)于冶煉錳(meng)(meng)硅合金(jin)。爐料預熱或裝入液態錳(meng)(meng)硅合金(jin)可(ke)使冶煉時間(jian)變(bian)短、使電(dian)耗(hao)變(bian)低(di)。精煉電(dian)耗(hao)一般(ban)在(zai)1000千瓦(wa)?時左右。中、低(di)碳錳(meng)(meng)鐵也用(yong)熱兌法,通(tong)過液態錳(meng)(meng)硅合金(jin)和(he)錳(meng)(meng)礦石(shi)、石(shi)灰熔體的(de)相互熱兌進行生產(chan)。吹(chui)(chui)氧(yang)精煉 用純氧(yang)吹(chui)(chui)煉液態碳素錳(meng)鐵或錳(meng)硅合金可煉得中、低碳錳(meng)鐵。此法經過多年試驗研(yan)究,于1976年進入工業(ye)規模生產。