高滑镁岩低品位镍矿的矿物特性及选矿试验研究

Study on Mineral Characteristics and Beneficiation Test on a Low-grade Nickel Ore with High-talc Magnesite

某镍矿石含镍0.65%,矿石类型以滑镁岩、蛇纹岩及菱镁岩为主,其中滑镁岩、蛇纹岩分别占矿石总量55%、25%,矿石中主要的金属矿物有磁黄铁矿、黄铁矿、磁铁矿、镍黄铁矿等,镍主要以镍黄铁矿的形式存在,约占总镍的85.67%,还有约13.08%的镍赋存于蛇纹石等硅酸盐矿物中,这部分镍难以回收;主要脉石矿物以滑石、蛇纹石、透闪石、绿泥石及菱镁矿等硅镁酸盐矿物为主,占矿物总量的70%以上,属于高硅高镁低品位难选镍矿石。矿石中矿物嵌布特征复杂,镍黄铁矿晶形为不规则他形粒状或条状,多嵌于磁黄铁矿边部,或与磁黄铁矿呈结状共生,嵌布粒度细,以0.010~0.070mm粒级居多,选别时需要考虑细磨才有助于镍矿物单体解离。采用乙基黄药与戊基黄药(1∶1)组合为捕收剂、六偏磷酸钠与CMC组合为脉石抑制剂、硫酸铜为活化剂、MIBC为起泡剂,闭路试验获得了镍精矿品位6.46%、精矿含MgO5.46%、镍回收率79.02%的较好技术指标。矿石中的脉石矿物滑石含量高、可浮性好,严重影响镍精矿质量,采用预先浮选脱泥去除大部分滑石,粗砂再通过六偏磷酸钠减弱或消除蛇纹石与滑石、绿泥石等矿物颗粒间的异相凝聚,最后采用CMC抑制易浮矿物,强化浮选的思路去处理高滑镁岩型低品位镍矿,提高了选别回收率,达到了资源综合利用的目的。

A nickel ore with nickel content of 0.65%is mainly composed of magnesite,serpentinite and magnesite,in which magnesite and serpentinite account for 55%and 25%of the total ore,respectively.The main metal minerals in the ore are pyrrhotite,pyrite,magnetite and pentlandite,and so on.Nickel is mainly in the form of pentlandite,accounting for 85.67%of the total nickel.About 13.08%of nickel exists in silicate minerals such as serpentine,which is difficult to be recovered.The main gangue minerals are talc,serpentine,tremolite,chlorite and magnesite,which account for more than 70%of the total minerals and belong to the low-grade refractory nickel ore with high silicon and magnesium.The dissemination characteristics of nickel minerals in the ore are complex,the crystal form of pentlandite is irregular xenomorphic granular or strip,which is mostly embedded in the edge of pyrrhotite,or intergrowth with pyrrhotite,the dissemination size is fine,mostly in the size fraction of 0.010—0.070 mm,fine grinding should be considered to help the liberation of nickel mineral monomer during separation.Using ethyl xanthate and amyl xanthate(ratio 1:1)combination as collector,sodium hexametaphosphate and CMC combination as gangue depressant,copper sulfate as activator,MIBC as frother,the locked-cycle test obtained a nickel concentrate with nickel grade of 6.46%,concentrate containing MgO 5.46%,nickel recovery of 79.02%.The gangue mineral in the ore has high talc content and good floatability,which seriously affects the quality of the nickel concentrate.The method comprises the following steps of:removing most of the talc by pre-flotation desliming,weakening or eliminating the heterogeneous agglomeration among mineral particles such as serpentine,talc,chlorite and the like by sodium hexametaphosphate for coarse sand,and finally,inhibiting easily-floated minerals by adopting CMC and strengthening the flotation to treat the high-talc magnesia-type low-grade nickel ore,which improves the sorting recovery and achieves the purpose of comprehensive utilization of resources.