金精矿中性焙烧过程中的物相转变及其磁性特征研究

Study on Phase Transformation and Magnetic Properties of Gold Concentrate in Neutral Roasting Process

针对载金硫化矿物黄铁矿在中性焙烧过程中反应行为研究较少的问题,分别采用热重-差示扫描量热分析、X射线衍射分析、扫描电镜、电子能谱分析和比磁化率仪等分析测试方法,研究了载金硫化矿物黄铁矿在不同焙烧温度和不同焙烧时间下的物相转变及其磁性特征。结果表明:在氮气环境下,随着焙烧温度的升高,金精矿中的黄铁矿热分解生成单质硫和磁黄铁矿,并伴随磁黄铁矿的进一步脱硫反应生成氧化亚铁,原本致密的黄铁矿颗粒变得疏松多孔,此结构有利于磨矿和金的高效浸出,焙烧产物的比磁化系数呈先增大后减小的趋势;随着焙烧时间的增加,黄铁矿逐渐消失,磁黄铁矿不断增多,焙烧产物的比磁化系数受焙烧程度影响明显,其随磁黄铁矿生成量的增大而升高,反之则降低。在焙烧温度为750℃、焙烧时间为45 min的条件下,焙烧产物的比磁化系数达到最大值1.94×10^(-5)m^3/kg,呈一定的弱磁性,为金精矿的磁选富集提供了可能。

Few research has been carried out on roasting reaction behavior of gold - bearing sulfide mineral pyrite under neutral atmosphere. Several analysis methods, such as thermogravimetric - differential scanning calorimetry, X - ray diffraction, scanning electron microscopy, energy disper-sive spectrum and specific susceptibility instrument were adopted in this paper. The phase transfor-mation and magnetic properties of gold - bearing sulfide mineral pyrite were investigated under dif-ferent roasting temperature and roasting time. The results showed that under a nitrogen atmosphere, along with the increase of roasting temperature, pyrite in gold concentrate was decomposed into sul-fur and pyrrhotite. Then pyrrhotite was further transformed into ferrous oxide by desulfurization re-action. Dense pyrite particles became porous, which was very favorable for grinding and efficient extraction of gold. Specific susceptibility firstly increased and then decreased. With the increase of roasting time pyrite gradually disappeared while pyrrhotite increased Specific susceptibility was influenced obviously by roasting degree, and it was changed with the same trend of pyrrhotite a-mount. Specific susceptibility reached to the maximum of 1.94 ×10^-5m^3/kg when roasting tempera-ture was 750℃ and roasting time was 45 min. Under this conditions, the roasting product has weak magnetism, which provides a possible way to enrich the gold concentrate with magnetic separation.