【作者】 刘德志；

【导师】 张国范；

【作者基本信息】 中南大学 ， 矿物加工工程， 2024， 博士

【摘要】 金川硫化铜镍矿是我国最大的硫化铜镍矿床,硫化矿的表面氧化一直是恶化其浮选指标的重要因素。过去关于硫化铜镍矿浮选过程中矿物氧化行为的研究主要以矿石中主要金属硫化矿物如镍黄铁矿、黄铜矿与磁黄铁矿的单矿物为研究对象,而忽视了不同硫化矿物之间的相互作用。硫化铜镍矿矿石中主要硫化矿物通常紧密共生,以连生体的形式存在,在混合浮选过程中,不同硫化矿物之间由于静电位的差异,将会发生伽伐尼效应,从而改变硫化矿物表面的电化学反应行为。为了进一步完善硫化铜镍矿浮选电化学理论,论文以镍黄铁矿、黄铜矿、磁黄铁矿为研究对象,在弱碱性条件下（p H=8.5）,对矿物之间的伽伐尼效应及其对混合体系中矿物的表面氧化行为、与捕收剂的作用方式、浮选行为的影响进行了系统研究,并探究了在硫化铜镍矿浮选过程中伽伐尼效应对矿物浮选行为的影响及调控机制,为硫化铜镍矿高效浮选以及精矿降镁提供一定的理论支持。论文主要研究内容以及所得结果如下:在200-600 mV的测试区间内,三种硫化矿物表面呈现出非理想N型半导体性质,镍黄铁矿、黄铜矿、磁黄铁矿的平带电位分别为284.65 m V、206.44 m V、89.35 m V。三种矿物可实现无捕收剂浮选的Eh范围由大到小依次为黄铜矿、镍黄铁矿、磁黄铁矿,这也对应了三种矿物的自诱导可浮性。在20 mg/L戊基黄原酸钾（potassium amyl xanthate,PAX）作用下,当p H<8.5时,三种矿物均有着极高的可浮性,而当p H>8.5时,三种矿物的可浮性由大到小依次为黄铜矿、镍黄铁矿、磁黄铁矿。在无捕收剂测试体系与PAX测试体系中,三种矿物的开路电位由高到低依次为镍黄铁矿、黄铜矿、磁黄铁矿,自腐蚀电流由大到小依次为磁黄铁矿、镍黄铁矿、黄铜矿。当其中两种不同的矿物混合时,伽伐尼效应将会促进阳极矿物（开路电位较低的矿物）的表面氧化反应。在无捕收剂体系中,伽伐尼效应将促进阳极矿物的氧化溶解,并伴随着H⁺的生成,从而导致阳极矿物表面亲水性Fe（III）-O组分的含量降低;阴极矿物表面氧化反应受到抑制,其表面主要发生O₂的还原反应,该反应产生的OH^-将促进Fe³⁺（主要来自于阳极矿物的溶解）在阴极矿物表面的沉淀。在含黄铜矿的混合体系中,需要考虑Cu²⁺对另外一种矿物的活化作用,在镍黄铁矿-黄铜矿体系中,Cu²⁺会在镍黄铁矿表面发生还原并生成Cu（I）-S₂组分,而在黄铜矿-磁黄铁矿体系中,Cu²⁺将在磁黄铁矿表面生成Cu（I）-S组分,该组分可能会与磁黄铁矿组成新的伽伐尼耦合对,从而进一步影响磁黄铁矿表面的阳极反应。当PAX存在时,伽伐尼效应将会促进PAX在阳极矿物表面的氧化,而对PAX在阴极矿物表面的氧化具有显著的抑制效果,处于混合体系中的阳极矿物表面双黄药含量增加,而阴极矿物表面双黄药含量显著降低。然而,在镍黄铁矿-黄铜矿体系及黄铜矿-磁黄铁矿体系中,黄铜矿氧化释放的Cu²⁺会促进PAX以黄原酸根的形式在镍黄铁矿或磁黄铁矿的表面发生吸附。在人工混合矿浮选体系中,黄铜矿的浮选行为变化较小,而镍黄铁矿与磁黄铁矿的可浮性将发生复杂的变化。伽伐尼效应对矿物浮选行为的影响同时受到矿浆p H、混合矿组成比例以及矿物自身氧化行为的影响。当三种矿物在弱碱性条件下以1:1:1的比例混合时,黄铜矿的可浮性基本不变,镍黄铁矿的可浮性降低,磁黄铁矿的自诱导浮选受到一定程度的促进,然而其PAX诱导可浮性将受到一定的抑制。硫化铜镍矿连生体中不同硫化矿物之间的伽伐尼效应将会显著提高连生体的氧化速率,在p H 2-12范围内,连生体的自诱导可浮性极差,当添加20 mg/L PAX后,连生体回收率呈现“双峰”结构,并在p H 4与9附近时达到峰值,分别为64.71%、54.35%。添加矿浆Eh调整剂能够调节矿浆Eh,从而影响连生体表面的电化学氧化行为,而Na₂S·9H₂O+Pb²⁺/Cu²⁺能够显著提高连生体表面硫化组分/氧化组分的比值,在适当的药剂用量下,采用上述药剂制度能够显著提高连生体的PAX诱导可浮性。实际矿浮选试验结果进一步证实采用上述调控手段可提高浮选初期矿石中硫化组分与镁硅酸盐脉石的浮选速率差异,从而改善精矿指标。图99幅,表31个,参考文献261篇更多还原

【Abstract】 Jinchuan Cu-Ni mine is the largest Cu-Ni sulfide deposits of China,and the surface oxidation of sulfides has historically been a difficult problem in Jinchuan concentrator.The past studies on the surface oxidation in Cu-Ni sulfide flotation process were mainly focused on the single constituent sulfide such as pentlandite,chalcopyrite and pyrrhotite,but the mutual effects between different sulfide minerals were ignored.The main constituent sulfides in Cu-Ni sulfide ores are normally closely associated with each other as a locked particle,which leads to the occurrence of galvanic interaction in the bulk flotation process due to their different rest potential,and the galvanic interaction between different sulfides will affect their surface electrochemical oxidation behaviors.To further improve the flotation electrochemistry theory of Cu-Ni sulfide ores,this work took pentlandite,chalcopyrite and pyrrhotite as the research objects,and systematical investigations on the galvanic interaction and its effect on the surface oxidation behaviors,reactions with PAX and flotation performance of the coupled minerals were conducted at p H 8.5.Besides,the effect of galvanic interaction on the flotation performance of Cu-Ni sulfide ores was also studied,and some regulating methods were applied to improve its flotation performance,which could provide some technical supports for the efficient flotation of Cu-Ni sulfide ores and reduced the Mg content in concentrates.Main research contents and the obtained results were summarized as follows:In the Eh range of 200-600 m V,the surfaces of pentlandite,chalcopyrite and pyrrhotite showed non-ideal N-type semiconductor characteristics,and the flat band potential of pentlandite,chalcopyrite and pyrrhotite was 284.65 m V、206.44 m V、89.35 m V,respectively.The Eh range that can achieve collectorless flotation of these minerals from large to small is chalcopyrite,pentlandite and pyrrhotite,which was also corresponding to their self-induced floatability.In the presence of 20mg/L potassium amyl xanthate（PAX）,when p H<8.5,all three minerals have a very high floatability,while p H>8.5,the floatability order of these minerals is chalcopyrite,pentlandite and pyrrhotite from high to low.In the absence or presence of 20 mg/L PAX,the rest potential of three minerals in sequence from high to low was:pentlandite,chalcopyrite,pyrrhotite.However,the rank（from high to low）of self-corrosion current of these minerals was:pyrrhotite,pentlandite,chalcopyrite.When two of them was coupled with each other,the surface oxidation reaction of anodic mineral（possessed a lower rest potential）was apparently enhanced.In the absence of PAX,the oxidation dissolution of anodic mineral was improved by galvanic interaction with the production of H⁺,resulting in the decrease in the content of hydrophilic Fe（III）-O species on anode surface.The surface oxidation of cathodic mineral would be depressed,while the generation of OH^-due to O₂ reduction would facilitate the precipitation of Fe³⁺on its surface in the form of Fe（III）-O,and the Fe³⁺was most likely originated from the anodic reaction.In the binary system containing chalcopyrite,the activation of Cu²⁺on another mineral should also be considered.In pentlandite-chalcopyrite system,the Cu²⁺generated from chalcopyrite oxidation would adsorb on pentlandite surface mainly in the form of Cu（I）-S₂,while in chalcopyrite-pyrrhotite system,Cu²⁺adsorbed on pyrrhotite surface mainly as the covellite-like（Cu（I）-S）species,which would like to build a new galvanic coupling pair with pyrrhotite,and the electrochemical oxidation behavior of pyrrhotite became more complicated.In the presence of PAX,the oxidation of PAX on cathodic minerals surfaces would be depressed by the galvanic interactions and the content of dixanthogen on their surfaces decreased,while the oxidative adsorption behaviors of PAX on anodic minerals was opposite.Furthermore,for the binary system containing chalcopyrite,the presence of Cu²⁺would promote the adsorption of PAX on another mineral in the form of xanthate.In the artificial mixed minerals flotation process,the flotation behavior of chalcopyrite showed a little variation,while the floatability of pentlandite and pyrrhotite varied complicatedly.The alteration actions of galvanic interaction on the flotation of contacted minerals would also be affected by pulp p H,the composition of mixed minerals and the spontaneous oxidation behaviors of the coupled minerals.In the ternary minerals（1:1:1）flotation system at p H 8.5,the galvanic interactions had a little effect on chalcopyrite flotation,while depressed the floatability of pentlandite,and the self-induced and PAX-induced flotation of pyrrhotite would be improved and inhibited to some extent,respectively.The galvanic interactions between different constituent minerals would greatly enhance the oxidation rate of the mixed Cu-Ni sulfide.In the p H range of 2-12,the self-induced flotation of the locked particle was not more than 10%,while in the presence of 20 mg/L PAX,the recovery of the locked particle presented a“double peaks”structure,and reached a peak value near p H 4 and p H 9,which were 64.71%and 54.35%,respectively.The addition of Eh regulators could adjust the pulp Eh,and alter the redox reactions on mineral surface.The addition of sodium sulfide+Pb²⁺/Cu²⁺greatly increased the ratio of sulfide components to oxidized components on mineral surface.When these reagents were used at an appropriate dosage,the PAX-induced flotation of mixed Cu-Ni sulfide was greatly improved.The batch flotation results further confirmed that the discrepancy between the flotation rate of sulfides and gangue minerals could be enlarged in the initial stage with these regulating methods,thereby,the concentration index was improved.更多还原