化工进展
化工進展
화공진전
CHEMICAL INDUSTRY AND ENGINEERING PROGRESS
2013年
10期
2308-2315
,共8页
卢杰%刘守军%上官炬%杜文广%潘峰%杨颂
盧傑%劉守軍%上官炬%杜文廣%潘峰%楊頌
로걸%류수군%상관거%두문엄%반봉%양송
氢气%红土镍矿%硫酸钠%晶相转变%磁选分离
氫氣%紅土鎳礦%硫痠鈉%晶相轉變%磁選分離
경기%홍토얼광%류산납%정상전변%자선분리
hydrogen%nickel laterite ore%sodium sulfate%crystalline phase transformation%magnetic separation
实验选用氢气为还原剂,无水硫酸钠为辅助添加剂,在实验室自制搅拌式气-固反应装置中通过改变温度、时间、Na2SO4用量、H2/N2比率对低品位红土镍矿进行选择性还原焙烧实验,焙烧矿通过磁选管进行磁选分离制备高品位镍铁合金。原矿、焙烧矿和磁选精矿的矿物学性质通过热力学计算并结合TG-DSC、H2-TPR、XRD、光学显微镜等分析仪器进行表征。实验结果表明:添加硫酸钠对促进红土矿晶相结构转变和提升H2的还原能力起到了积极的作用。还原温度作为供热源能够显著改善硫酸钠的催化反应活性,提高磁性产品中镍铁含量。在温度为800℃,总气速为200 L/h(H2/N2=7/3),还原时间为220 min的最优条件下,含20%硫酸钠的红土矿经还原-磁选后能够获得镍品位6.43%,镍回收率97%的较好指标。从热力学角度分析,根据吉布斯自由能图和平衡气相图看出硫酸钠能与矿物中的硅酸镁(MgSiO3)在700℃左右即可自发反应释放出赋存于其中的镍,反应生成的SO2能够促使FeO转变为FeS,FeS则有助于Fe-S低熔点固溶体的形成,从而促进镍铁粒子的定向转移和聚集长大,便于后续磁选中磁性镍铁矿物与脉石矿物的分离。
實驗選用氫氣為還原劑,無水硫痠鈉為輔助添加劑,在實驗室自製攪拌式氣-固反應裝置中通過改變溫度、時間、Na2SO4用量、H2/N2比率對低品位紅土鎳礦進行選擇性還原焙燒實驗,焙燒礦通過磁選管進行磁選分離製備高品位鎳鐵閤金。原礦、焙燒礦和磁選精礦的礦物學性質通過熱力學計算併結閤TG-DSC、H2-TPR、XRD、光學顯微鏡等分析儀器進行錶徵。實驗結果錶明:添加硫痠鈉對促進紅土礦晶相結構轉變和提升H2的還原能力起到瞭積極的作用。還原溫度作為供熱源能夠顯著改善硫痠鈉的催化反應活性,提高磁性產品中鎳鐵含量。在溫度為800℃,總氣速為200 L/h(H2/N2=7/3),還原時間為220 min的最優條件下,含20%硫痠鈉的紅土礦經還原-磁選後能夠穫得鎳品位6.43%,鎳迴收率97%的較好指標。從熱力學角度分析,根據吉佈斯自由能圖和平衡氣相圖看齣硫痠鈉能與礦物中的硅痠鎂(MgSiO3)在700℃左右即可自髮反應釋放齣賦存于其中的鎳,反應生成的SO2能夠促使FeO轉變為FeS,FeS則有助于Fe-S低鎔點固溶體的形成,從而促進鎳鐵粒子的定嚮轉移和聚集長大,便于後續磁選中磁性鎳鐵礦物與脈石礦物的分離。
실험선용경기위환원제,무수류산납위보조첨가제,재실험실자제교반식기-고반응장치중통과개변온도、시간、Na2SO4용량、H2/N2비솔대저품위홍토얼광진행선택성환원배소실험,배소광통과자선관진행자선분리제비고품위얼철합금。원광、배소광화자선정광적광물학성질통과열역학계산병결합TG-DSC、H2-TPR、XRD、광학현미경등분석의기진행표정。실험결과표명:첨가류산납대촉진홍토광정상결구전변화제승H2적환원능력기도료적겁적작용。환원온도작위공열원능구현저개선류산납적최화반응활성,제고자성산품중얼철함량。재온도위800℃,총기속위200 L/h(H2/N2=7/3),환원시간위220 min적최우조건하,함20%류산납적홍토광경환원-자선후능구획득얼품위6.43%,얼회수솔97%적교호지표。종열역학각도분석,근거길포사자유능도화평형기상도간출류산납능여광물중적규산미(MgSiO3)재700℃좌우즉가자발반응석방출부존우기중적얼,반응생성적SO2능구촉사FeO전변위FeS,FeS칙유조우Fe-S저용점고용체적형성,종이촉진얼철입자적정향전이화취집장대,편우후속자선중자성얼철광물여맥석광물적분리。
Hydrogen was experimentally selected as a reducing agent and sodium sulfate as an auxiliary additive. The reduction of the low-grade nickel laterite ore was carried out in a self-made gas-solid reactor with provisions for agitation control by changing the temperature,time,Na2SO4 dosage and H2/N2 volume ratio,and the magnetic separation of the reduced ore was performed using a magnetic separator to prepare high-grade nickel-iron alloy. The mineralogical properties of the raw laterite ore,reduced ore and magnetic concentrate were characterized using thermodynamical calculation,differential thermogravimetry-differential scanning calorimeters (DTG-DSC), hydrogen-temperature programmed reduction (H2-TPR),X-ray diffractometry(XRD),and optical microscopy. The experimental results show that the addition of sodium sulfate could accelerate the crystal phase transition of laterite ore and elevate the utilization of H2. The increase of reduction temperature , as a heat source , could enhance the catalytic reaction activity of sodium sulfate significantly and improve the content of nickel and iron of magnetic product. The optimal reduction condition was obtained as the selective reduction of laterite ore at 800℃ for 220 min in the presence of 20% Na2SO4 with an inlet gas mixture of 70% H2 in N2 at a total gas flow rate of 200 L/h. The maximum nickel content and recovery of magnetic product were 6.43%and 97%,respectively. From a thermodynamic point of view,it can be known according to the Gibbs free energy and equilibrium vapor phase diagrams that the sodium sulfate could react with MgSiO3 which exists in the minerals spontaneously at around 700 ℃ and release the nickel. Besides,the generated SO2 could promote FeO transform into FeS,which were conductive to the formation of Fe-S solid solution and thereby contributed to directional mass transfer,accelerated the coalescence of metallic ferronickel particles and facilitated the downstream magnetic separation.