碱度对腐泥土型红土镍矿烧结行为的影响

Effect of bacisity on sintering behavior of saprolitic nickel laterite

为了研究腐泥土型红土镍矿在焙烧过程中物相转变及固结机制问题,通过微型烧结试验和三角锥法软熔特性试验,对原矿和焙烧后的团块进行了化学成分、X射线衍射(XRD)和软熔特性分析,并通过添加熔剂CaO改变团块碱度,结合冶金相图进行了分析。研究结果表明,自然碱度的红土镍矿经高温焙烧后主要由尖晶石(MgFe_2O_4)、镁橄榄石((Mg,Fe)_2SiO_4)和顽火辉石(MgSiO_3)构成。随着碱度从0.5上升到2.0,顽火辉石相继转变为低熔点的透辉石(CaMgSi_2O_6)和高熔点的镁黄长石(Ca_2MgSi_2O_7)以及镁蔷薇辉石(Ca_3MgSi_2O_8)。红土镍矿的软熔温度也随碱度的提高先降低后升高,在碱度为1.0时达到最低点。结合冶金相图分析得知,通过改变碱度可以显著增加红土镍矿烧结过程液相量,红土镍矿烧结理想的黏结相为透辉石。

In order to understand the phase transformation and consolidation mechanism of saprolitic nickel laterite ore, the chemical analysis, X-ray diffraction analysis and fusion property of the green briquettes as well as the roasted briquettes were carried out according to the micro sintering experiment and fusion characteristic experiment using the three-pyramid method. The metallurgycal phase diagram was also analyzed on the condition of the addition of CaO, which was usually use as flux in sintering process. Experimental results shown that the main minerals formed during sin- tering with natural basicity were refractory materials such as spinel （MgFe：O4）, forsterite （（Mg, Fe）2SiO,） and enstatite （MgSiO3）, which were all minerals with rather high fusion temperature. With increasing basicity from natural basicity 0.5 to 2.0 according to adjusting the addition proportion of CaO, the enstatite firstly transformed to dipophide （CaMg- Si206） with lower fusion temperature. With the increasing content of CaO in the laterite ore briquitte, the akermanite （Ca2MgSi2OT） and merwinnite （Ca3MgSi200 with higher fusion temperature were generated in succession. All the three fusion characteristic temperatures decreased initially and then increased with a valley at the basicity of 1.0. It＇s revealed that the amount of binder phase could be increased significantly by adjusting basicity, and the ideal binder phase for sin- tering of saprolitic laterite ore was diposide.