武漢電熔鎂砂是重(zhong)要的(de)工(gong)業原材料(liao)，其生(sheng)產(chan)工(gong)藝(yi)簡單，主要以(yi)氧化鎂(mei)(mei)壓球料(liao)為(wei)原料(liao)，采用電(dian)弧爐熔融法(fa)制(zhi)備而成(cheng)。我國(guo)電(dian)熔鎂(mei)(mei)砂制(zhi)備工(gong)藝(yi)技術方面的(de)研究成(cheng)果，主要表現在選擇(ze)適(shi)宜(yi)的(de)化學添加劑改善鎂(mei)(mei)砂的(de)性能以(yi)及(ji)高效新工(gong)藝(yi)的(de)開(kai)發(fa)。

我(wo)國電(dian)熔鎂(mei)砂制備工藝及應用(yong)

      我國(guo)電(dian)熔鎂砂(sha)制備優化(hua)工(gong)藝。當前我國(guo)電(dian)熔鎂產(chan)(chan)(chan)業(ye)仍在(zai)沿用電(dian)弧爐生(sheng)產(chan)(chan)(chan)方(fang)式，技術裝備相對落后，效(xiao)率低，能源(yuan)浪費嚴重，余熱潛能流失嚴重;電(dian)熔鎂砂(sha)生(sheng)產(chan)(chan)(chan)過程中(zhong)還存在(zai)著嚴重的粉塵污染(ran)，并大量排放二氧化(hua)碳，加重了大氣溫(wen)室(shi)效(xiao)應，惡化(hua)周邊環(huan)境。現有(you)電(dian)熔鎂技術裝備亟待更新(xin)換代，現有(you)工(gong)藝急需創新(xin)，因此，采用集成(cheng)技術發展(zhan)節(jie)能環(huan)保的新(xin)式電(dian)熔鎂裝備及(ji)制備工(gong)藝是(shi)發展(zhan)電(dian)熔鎂產(chan)(chan)(chan)業(ye)的重要選(xuan)擇。

      近年來，國內的(de)科技(ji)工(gong)作者在電(dian)(dian)熔鎂(mei)(mei)砂(sha)的(de)生(sheng)產(chan)(chan)工(gong)藝(yi)方面進行了(le)改(gai)進和優化(hua)(hua)(hua)，并(bing)取得了(le)一定(ding)的(de)成效。電(dian)(dian)熔鎂(mei)(mei)砂(sha)的(de)生(sheng)產(chan)(chan)工(gong)藝(yi)流程短(duan)而(er)簡單，但設備(bei)投入和資源消耗大。我國電(dian)(dian)熔鎂(mei)(mei)砂(sha)產(chan)(chan)業多采用(yong)電(dian)(dian)弧爐熔融天然菱鎂(mei)(mei)礦石制(zhi)備(bei)電(dian)(dian)熔鎂(mei)(mei)砂(sha)，生(sheng)產(chan)(chan)工(gong)藝(yi)技(ji)術裝備(bei)落后(hou)，功率低(di)、容量小、效率低(di)、自動化(hua)(hua)(hua)程度(du)低(di)，生(sheng)產(chan)(chan)出的(de)電(dian)(dian)熔鎂(mei)(mei)砂(sha)產(chan)(chan)品品位(wei)不高，導致(zhi)鎂(mei)(mei)資源利(li)用(yong)率低(di)，環境污染嚴重。通過利(li)用(yong)鹽湖(hu)鹵水(shui)與氨(an)氣反(fan)應后(hou)生(sheng)成氫(qing)氧化(hua)(hua)(hua)鎂(mei)(mei)在煅燒后(hou)生(sheng)成輕(qing)質氧化(hua)(hua)(hua)鎂(mei)(mei)，可以通過洗(xi)滌、過濾等(deng)方法有效地除去(qu)雜質離子，氧化(hua)(hua)(hua)鎂(mei)(mei)的(de)純(chun)度(du)高達99.9%，在較低(di)溫度(du)下輕(qing)燒得氧化(hua)(hua)(hua)鎂(mei)(mei)粉(fen)末，而(er)后(hou)經一定(ding)壓力壓球(qiu)，制(zhi)取高純(chun)電(dian)(dian)熔鎂(mei)(mei)砂(sha)。

電熔(rong)鎂砂(sha)熔(rong)煉過(guo)程研究

      電(dian)(dian)(dian)(dian)熔(rong)(rong)(rong)(rong)鎂(mei)砂熔(rong)(rong)(rong)(rong)煉工藝原理。電(dian)(dian)(dian)(dian)熔(rong)(rong)(rong)(rong)鎂(mei)砂是(shi)采用(yong)電(dian)(dian)(dian)(dian)弧熔(rong)(rong)(rong)(rong)融法進行制備(bei)，其裝備(bei)是(shi)電(dian)(dian)(dian)(dian)熔(rong)(rong)(rong)(rong)鎂(mei)電(dian)(dian)(dian)(dian)弧爐(礦(kuang)熱(re)埋弧電(dian)(dian)(dian)(dian)爐)，即(ji)通(tong)過(guo)電(dian)(dian)(dian)(dian)極的埋弧電(dian)(dian)(dian)(dian)熱(re)和物(wu)料的電(dian)(dian)(dian)(dian)阻電(dian)(dian)(dian)(dian)熱(re)來(lai)熔(rong)(rong)(rong)(rong)煉物(wu)料。其電(dian)(dian)(dian)(dian)耗很(hen)大(da)，爐體一般呈圓形，三根電(dian)(dian)(dian)(dian)極布置成三角形。電(dian)(dian)(dian)(dian)熔(rong)(rong)(rong)(rong)鎂(mei)爐在生產過(guo)程中，是(shi)以電(dian)(dian)(dian)(dian)弧電(dian)(dian)(dian)(dian)熱(re)對爐料加熱(re)使之熔(rong)(rong)(rong)(rong)化(hua)，形成熔(rong)(rong)(rong)(rong)池(chi)，電(dian)(dian)(dian)(dian)弧電(dian)(dian)(dian)(dian)熱(re)越大(da)，物(wu)料熔(rong)(rong)(rong)(rong)化(hua)的速(su)度越快。

      電熔鎂砂的(de)制(zhi)(zhi)備是以(yi)氫氧(yang)化鎂煅燒氧(yang)化鎂壓制(zhi)(zhi)成球后(hou)為原料(liao)，在(zai)4000kVA高溫電弧爐(lu)中(zhong)經(jing)冶煉、熔化再結晶(jing)后(hou)形成的(de)鎂砂制(zhi)(zhi)品，在(zai)不同類(lei)型(xing)的(de)電弧爐(lu)中(zhong)通過(guo)電弧加(jia)熱(re)(re)產生高溫(≥2800℃)，使鎂質(zhi)原料(liao)在(zai)爐(lu)中(zhong)受熱(re)(re)、脫水(釆用(yong)水氯(lv)鎂石(shi))、溶(rong)融、析(xi)晶(jing)、晶(jing)體長大(da)(da)、冷卻等一系列物理化學(xue)變化過(guo)程，形成一種(zhong)耐高溫、硬度大(da)(da)、純度高的(de)電熔氧(yang)化鎂晶(jing)體。

      電(dian)(dian)(dian)熔(rong)鎂砂(sha)的熔(rong)煉(lian)過程主要分(fen)為填料(liao)階(jie)(jie)(jie)(jie)(jie)(jie)段(duan)(duan)(duan)(duan)、起(qi)(qi)弧(hu)(hu)階(jie)(jie)(jie)(jie)(jie)(jie)段(duan)(duan)(duan)(duan)、熔(rong)融階(jie)(jie)(jie)(jie)(jie)(jie)段(duan)(duan)(duan)(duan)、加(jia)料(liao)階(jie)(jie)(jie)(jie)(jie)(jie)段(duan)(duan)(duan)(duan)、冷卻階(jie)(jie)(jie)(jie)(jie)(jie)段(duan)(duan)(duan)(duan)以及停爐階(jie)(jie)(jie)(jie)(jie)(jie)段(duan)(duan)(duan)(duan)：填料(liao)階(jie)(jie)(jie)(jie)(jie)(jie)段(duan)(duan)(duan)(duan)。在(zai)(zai)電(dian)(dian)(dian)熔(rong)開(kai)(kai)(kai)始(shi)工作之(zhi)前(qian)需(xu)往爐內裝料(liao)，應做到將(jiang)料(liao)壓(ya)實壓(ya)密(mi)，并(bing)在(zai)(zai)粉料(liao)的最上層鋪(pu)一層工業冶金焦炭(tan)，其平鋪(pu)范(fan)(fan)圍在(zai)(zai)三(san)根電(dian)(dian)(dian)極(ji)(ji)所形成的三(san)角形范(fan)(fan)圍內，使(shi)得起(qi)(qi)弧(hu)(hu)后(hou)電(dian)(dian)(dian)路形成回路;起(qi)(qi)弧(hu)(hu)階(jie)(jie)(jie)(jie)(jie)(jie)段(duan)(duan)(duan)(duan)。調節電(dian)(dian)(dian)極(ji)(ji)，開(kai)(kai)(kai)始(shi)進(jin)入(ru)起(qi)(qi)弧(hu)(hu)階(jie)(jie)(jie)(jie)(jie)(jie)段(duan)(duan)(duan)(duan);熔(rong)融階(jie)(jie)(jie)(jie)(jie)(jie)段(duan)(duan)(duan)(duan)。起(qi)(qi)弧(hu)(hu)后(hou)，待(dai)電(dian)(dian)(dian)流趨于平穩(wen)后(hou)，電(dian)(dian)(dian)極(ji)(ji)周圍的原料(liao)開(kai)(kai)(kai)始(shi)熔(rong)融，熔(rong)池逐(zhu)漸形成;加(jia)料(liao)階(jie)(jie)(jie)(jie)(jie)(jie)段(duan)(duan)(duan)(duan)。

      隨氧(yang)(yang)化(hua)鎂(mei)(mei)原料不(bu)斷消(xiao)耗(hao)，熔(rong)(rong)池(chi)液面開(kai)始下降(jiang)，待熔(rong)(rong)池(chi)穩(wen)定后可往(wang)(wang)電(dian)極(ji)周圍(wei)填料，進入加(jia)(jia)料階(jie)(jie)段(需注意不(bu)要破壞熔(rong)(rong)池(chi)的穩(wen)定性);冷(leng)卻階(jie)(jie)段。熔(rong)(rong)煉完成(cheng)后，電(dian)極(ji)逐漸(jian)被(bei)氧(yang)(yang)化(hua)消(xiao)耗(hao)，電(dian)流(liu)減小。需通過(guo)冷(leng)卻給熔(rong)(rong)池(chi)內的氧(yang)(yang)化(hua)鎂(mei)(mei)晶體創(chuang)造(zao)一(yi)個穩(wen)定散熱降(jiang)溫的環境，使其(qi)冷(leng)凝結晶出多晶氧(yang)(yang)化(hua)鎂(mei)(mei)產(chan)品;停爐(lu)階(jie)(jie)段。停爐(lu)過(guo)程中(zhong)，往(wang)(wang)往(wang)(wang)采用手動加(jia)(jia)料，為了減少排氣，電(dian)極(ji)附近要加(jia)(jia)入氧(yang)(yang)化(hua)鎂(mei)(mei)坯砂(sha)(氧(yang)(yang)化(hua)鎂(mei)(mei)輕燒粉(fen)不(bu)含(han)CO2)，并多加(jia)(jia)細粉(fen)料，有利于產(chan)品產(chan)量及(ji)品質提高(gao)。電(dian)熔(rong)(rong)鎂(mei)(mei)砂(sha)熔(rong)(rong)融(rong)結晶過(guo)程。

      電熔(rong)(rong)鎂砂(sha)的(de)熔(rong)(rong)融(rong)結晶(jing)過程伴(ban)隨(sui)著雜(za)(za)質(zhi)(zhi)(zhi)的(de)遷移和析出，在(zai)熔(rong)(rong)煉過程中(zhong)，由于各(ge)組分(fen)的(de)熔(rong)(rong)點(dian)和密(mi)(mi)度(du)(du)(du)(du)不同，其(qi)析出方(fang)式存在(zai)差異：熔(rong)(rong)融(rong)開始時(shi)，隨(sui)溫(wen)度(du)(du)(du)(du)的(de)升高，熔(rong)(rong)點(dian)較低的(de)雜(za)(za)質(zhi)(zhi)(zhi)先(xian)達(da)到(dao)(dao)熔(rong)(rong)點(dian)溫(wen)度(du)(du)(du)(du)，并轉變(bian)成液態;隨(sui)溫(wen)度(du)(du)(du)(du)繼續升高，當(dang)達(da)到(dao)(dao)氧(yang)(yang)化(hua)(hua)鎂熔(rong)(rong)點(dian)溫(wen)度(du)(du)(du)(du)時(shi)，此時(shi)氧(yang)(yang)化(hua)(hua)鎂開始熔(rong)(rong)化(hua)(hua)，因氧(yang)(yang)化(hua)(hua)鎂的(de)密(mi)(mi)度(du)(du)(du)(du)相對(dui)較高，其(qi)它雜(za)(za)質(zhi)(zhi)(zhi)的(de)密(mi)(mi)度(du)(du)(du)(du)相對(dui)較低，加上熔(rong)(rong)池中(zhong)二氧(yang)(yang)化(hua)(hua)碳和水蒸氣的(de)不斷上升，使得(de)雜(za)(za)質(zhi)(zhi)(zhi)逐漸向上遷移。

      總之，目前電熔(rong)(rong)鎂(mei)砂(sha)(sha)傳統生產(chan)工(gong)藝(yi)是以菱鎂(mei)礦為原料，通過(guo)電弧(hu)爐高(gao)(gao)(gao)(gao)溫(wen)熔(rong)(rong)煉制(zhi)備而成，但(dan)該法存(cun)在產(chan)品(pin)質量(liang)不高(gao)(gao)(gao)(gao)、生產(chan)能耗高(gao)(gao)(gao)(gao)、環(huan)境(jing)污染嚴(yan)重、工(gong)作強(qiang)度(du)大等缺(que)陷。而利(li)用鹽湖鹵水制(zhi)備的高(gao)(gao)(gao)(gao)純Mg(OH)2中間體為原料生產(chan)高(gao)(gao)(gao)(gao)純電熔(rong)(rong)鎂(mei)砂(sha)(sha)，具有產(chan)品(pin)附加值高(gao)(gao)(gao)(gao)、生產(chan)處理量(liang)大、能耗低(di)等優異特點，解決了國內外高(gao)(gao)(gao)(gao)端鎂(mei)砂(sha)(sha)制(zhi)品(pin)的需求。因(yin)此(ci)，該工(gong)藝(yi)是今后(hou)高(gao)(gao)(gao)(gao)純電熔(rong)(rong)鎂(mei)砂(sha)(sha)制(zhi)備的主流(liu)方向(xiang)。

電熔鎂砂