The gangue sponge: implications for in-situ/heap leaching of chalcopyrite

(Partial) dissolution of reactive aluminosilicate gangue minerals increase the complexity of chalcopyrite leaching by forming an amorphous, porous silica residue that interacts with the leaching solution to form local non-equilibirum microenvironments. Reactive phyllosilicates chamosite and kaolinite minerals berthierine and greenalite sample mineralogy and bulk chemistry is determined by XRD, XRF, Moessbauer Spectroscopy and OES. After leaching, the leaching solution chemistry was analysed via OES and UV-VIS. The leaching residue textures, chemistry and cpy S-oxidation state was analysed using SEM, FIB, uXRF and uXANES. Heterogeneous element distribution in the porous textures and leaching solution, as well as chalcopyrite and pyrite textures reveal incongruent dissolution of reactive gangue minerals that form a porous amorphous silica residue that can entrap and penetrate Cu sulfides. The pores of the ASR form local microreactors with variable non equilibium conditions of the lixiviant, that lead to larger variety and more complex S oxidation states on chalcopyrite grains. Gangue mineral dissolution hence influences chalcopyrite leaching reactions and Cu recovery.

部分溶解的活性铝硅酸盐脉石矿物增加了黄铜矿浸出的复杂性，这是因为它们形成了非晶质的多孔二氧化硅残留物，该残留物与浸出溶液相互作用，形成局部非平衡微环境。反应性叶状硅酸盐矿物如绿泥石和粘土矿物贝特瑞宁和绿色辉石样本的矿物学和全岩化学通过X射线衍射（XRD）、X射线荧光光谱（XRF）、莫塞巴乌谱学和光电子能谱（OES）确定。浸出后，浸出溶液的化学成分通过光电子能谱（OES）和紫外-可见光谱（UV-VIS）进行分析。浸出残留物的纹理、化学成分以及黄铜矿的S氧化态通过扫描电子显微镜（SEM）、聚焦离子束（FIB）、微区X射线荧光光谱（uXRF）和微区X射线吸收近边结构（uXANES）进行分析。孔隙状纹理和浸出溶液中的异质元素分布，以及黄铜矿和黄铁矿的纹理揭示了活性脉石矿物的溶解不均匀，形成了多孔的非晶质二氧化硅残留物，这些残留物可以捕获并渗透铜硫化物。碱激发反应（ASR）的孔隙形成局部微反应器，具有可变的非平衡浸出剂条件，导致黄铜矿颗粒上出现更多样化和更复杂的S氧化态。因此，脉石矿物的溶解对黄铜矿浸出反应和铜的回收率产生显著影响。